7lVS/o5S-TT/ I— re E S- o c O S- o 4- (/) TO ZJ ro CO > LU c fD o 1— •■- +-> Its E i- o r Procedures Manual < Library Search Commercial Search Services Questionnaire Personal Interviews r Library of Acquired Information New References < V Annotated Bibl iography V Train Readers Abstract Articles and Information I Fill Out Data Sheets i Review and Edit Data Sheets Keypunch Edit Data Base See Fiqure 3 lgi ± Structure Data Printout Interactive Inquiry Keyword Index Interpretation and Evaluation of Information Final Report Primary Author Reference Number Index Figure 2. Flow chart of the methods of investigation. 6 T3 cu +-> o 3 "O c o o to 3 CD •i— > s- cu +-> c •|_ , — ra c o CO OO i. Q. d) S- Q. n3 T3 c c c fO o ■r- 1 +J +J ► •' — oo 7 00 on s- •r— 4-> E c o 2 •1- 00 > s- •i- a> ai a. UJ o o i i £ a> 4- S- o a. H o o <0 i i o o -J •♦ a> CO CO Q_ t— CO LO —. O I— I— CO CO KUUI- 1— >- or too.<- O CO • i «t lu or •— < >- c~ r 5 CO o ■=c >— sn z: CI—*— o or or c < I- 1— 1— O- CD LU r ■> O UJ t— t— z- O 1— z SUBSTRAT ENVIRONM FLORA VERTEBRA IMVERTEB ECOLOGIC SHORT TE SHORT TE LONG TEP LONG TEF OTHERS 1 . ■ c .". (. : D ZT lu cr =3 h- z: O <£ c UJ •— _I _! UJ CJ CO z: t— z: o or o f UJ UJ •— i LU - uj •— e: c: :r oriui-a: zh I k1 Ul I i— « O ■— ' CO . >-. u_ *— o u_ i— or i ct lj ii c r < " : c or l— — • O. I— «=c c CJ •a: < => 1- \— cs u_ DL 1 _j ■=: uj u_ lu or 1— )— zc UJ oa>ci UJ 31 ID z: « cr co CO LU ■ e e: h- ro j »-* z: -« z: or LU LU IT CO u h- z: o o or >1M_|U uj z: CUOI CJ o •ZL O — 1- < <; o uj o _j 3: _j >-• a vl ujl- O o o CM l/l >> CO CO re .a ro "O co CD t- +-> O 3 S- +J CO CD CD S_ o CD data base for each structure type was made based on the number of available references and their ratings. Germane studies in progress were identified and the potential contribution to the state of the art projected. Case histories of the impact of the shoreline structures were also prepar- ed. Wherever possible, the case history included information about the biological and physical environment before and after construction of the structure, an evaluation of the effectiveness of the structure, and an evaluation of the im- pacts of the structure on the physical environment and on fish and wildlife habitat. The text (Volume 1), the primary author reference number index, the keyword index, and the annotated bibli- ography (Volume 2) comprise the final report. SUMMARY OF LITERATURE BREAKWATERS Definition A breakwater is a structure offer- ing wave protection to a shore harbor, anchorage, or basin. Breakwaters are usually "constructed to create calm wa- ter in a harbor area, and provide pro- tection for safe mooring, operating and handling of ships, and protection for harbor facilities" (U.S. Army Corps of Engineers 1973b). Breakwaters may be further defin- ed as fixed or floating, and shore-con- nected or detached. Fixed breakwaters are built up from the ocean, lake, or estuarine floor while floating breakwa- ters float at or near the water surface and are held in place by a system of tethers and anchors. Shore-connected breakwaters have a connection to exist- ing land while detached breakwaters are not connected to the land. A detached breakwater might also be called a paral- lel or offshore breakwater. Shore-con- nected breakwaters are structurally sim- ilar to jetties, but differ in function in that their primary purpose is to reduce wave energy, not to maintain water depth. Some structures function as breakwaters and jetties. Figure 5 is a photograph of a con- nected coastal breakwater which was constructed to offer protection for a natural harbor. Figure 6 is a photo- graph of an offshore breakwater which was constructed to create a harbor. Figure 7 contains an example of a float- ing breakwater. Structure Functions Probably the best known use of breakwaters is to create or enhance harbors for large or small craft. Nor- mally these shore-connected breakwaters extend into a body of water to provide protection from waves caused by either wind or passing vessels. Breakwaters constructed to create a harbor may ad- ditionally protect the shoreline from erosion, alter longshore sediment trans- port, and support pedestrian or vehicu- lar traffic requiring access to deeper waters of a harbor or adjacent area. Detached breakwaters may be used to prevent or reduce wave penetration into a harbor entrance or to reduce the wave attack on a costly structure, such as a seawall or a power plant. Detached breakwaters may also be used as sand traps due to the tendency of sand to ac- crete on the beach in the lee of the breakwater. Site Characteristics and Environmental Conditions Shore-connected breakwaters often have the connected end lying perpendic- ular to the shoreline and the free end lying parallel to the shoreline (Figure 5). In most cases, detached, or off- shore, breakwaters are parallel to the shore (Figure 6). Shore-connected break- waters are placed according to site-spe- cific functional requirements. Breakwa- ters are most commonly used to provide a sheltered harbor and, consequently, are placed where they create an area with minimum wave and surge action (U.S. Army Corps of Engineers 1973b). When asso- ciated with harbors and marinas, break- waters usually define boundaries and provide navigation channels, as well as enclosing areas of lowered wave energy. Because their primary function is energy dissipation, breakwaters are usually placed in high-energy environments, such as coastal areas, semienclosed, or en- closed bodies of water where there is a long fetch or high occurrence of vessel- generated waves. In at least one case, however, breakwaters contributed to wave resonance and caused considerable surge within the harbor, resulting in boat damage (Slawson 1977). Breakwater place- ment is often determined by the exist- ence of a shoreline area suitable for harbor facilities rather than by bottom topography, littoral processes, or other factors. The biota of breakwater sites has apparently had little study. No general- izations can be made, based on existing data, concerning bottom characteristics, water quality, flora and fauna, or eco- logical interrelationships at locations where breakwaters have been planned or 10 01 > 5 ■o I" 0J S_ -o O oo Q- => to cu o 4- Ol O CO S- >> o i/) CO »* +-> T3 S- S_ 3 o o t- o S- o -C a. 4-> (0 <~ s_ o en Q. O 4-> +-> O to .c Qu S- o -O ■ S- i. (O CU j= +-> nj ■a 5 O) .V +j ro o CD • co S- C +-> -Q O o cn S_ en CO o_ cu s_ .— O >> a> ^~ O « ^~ -O T3 n3 c s- -O (O 3 CU >— +-> 4-> -t-> n3 O S_ C CO O C Q- i — c ^~ o « >■•-> -O (/) •^ • C Q ir> o •i- s_ +-> CO a> O CO i- CO c 3 +-> •!- CD O 0> •i— s- c U. Q.LU 11 s- QJ +■> 03 3 ^a co 10 •1 — CD a> S- S- _C _Q qj +j CD n3 M- S_ 3 o O H. £ re >> on QJ oo t- S- QJ <+- -Q 4-> O S- 0J a> o .c l— u +J cd O -C >) •a n. -Q CO -a s- T3 QJ CD CU -£= O T3 O +J $- (O o O +-> -£= ■+- +-> Q- 4- 03 03 c on «=C -c "*~ D. re '0 • s_ C CD CD • r— £Z O s_ •i- 4-> 03 £ o ^ on .c 3 Q. . CD r— CO t — M- QJ CU o jr • f— JC -a +-> 5- 00 o cu i — o «•- JZZ ■i" CD O O0 SI •^ go 3 S- o a> u_ 4-> •a zs QJ o +-> S- 00 QJ 03 Q. ro -E +J 3 +J in . re c sz CO c •!- o ■ r— +J S- QJ CD QJ re i— C S- E -Q -(— =5 •r— JZ CP QJ CO CO ■ r— -SZ -i- 03 u_ (— > 3 12 «=t OJ • Q. o s_ en a) CU -Q S- E O T- +J >> OJ ro -C en +-> ro -o c c: •i- ro cr i- ro cu >- +-> ro c 3 •.- j*: ro • ro cu o c s- c •p- -O i— • s_ 10 Ol ' (X3 +-> -i- rO 31 01 O S- i— s: CD 14- CM ■+-> :r i— cu CJ cu -C _C +-> 4- l/l O e s- , CO 3 cu (C 4J -M 2 CU S- -^ jQ 3 ro O HI 1/1 u i. +-> ■i- Q. tux IO c a> s- •i- CD +-> i— o ro CU 4-> O C O r— C -C 4- ro Q- < <-> sz i- • O CU r-^. -r- +J +-> ro CU ro S S_ Cn.^ 23 -i- re en > CU •i- ro S_ Li- C -Q 13 constructed. Comrr unities which occur on breakwaters are those characteristic of intertidal and subtidal rocky shores. The exposed side is often characterized by communities adapted to high-energy environments while the back side is generally inhabited by organisms typical of less hostile environments. Placement Constraints Enqineering. Breakwater design must consider the physical environment in which the structure is to be placed, the availability and cost of construction materials, and the function of the struc- ture. In addition to these factors, the effects of the breakwater upon its envi- ronment must be considered. Design criteria for fixed breakwa- ters must consider several factors of the physical environment, including wave climate, sediment transport, bot- tom topography, characteristics of the protected areas, tides, and currents at the site. The design wave and the max- imum wave must be determined. At this point a trade-off is often necessary be- tween economic feasibility and failure- proof design (Saville et al. 1965). A generalized diagram of a typical rubble- mound breakwater is contained in Fig- ure 8. After the design wave is determin- ed for the construction site, other fac- tors must be considered. Studies must be made of the subtrate upon which the breakwater will rest to determine what precautions must be taken to prevent settling and erosion of foundation mate- rial (Saville et al. 1965). Prevention of erosion and settling is often accomplish- ed by using filter blankets cr mats sim- ilar to those used under revetments. This filter cloth material prolongs the settling of the breakwater stones into the substrate, which occurs due to the weight of the materials and slight move- ment due to wave attack. The core, cap, facing, and foundation material of the breakwater must be chosen to pre- vent damage or component displacement by the design wave. Wave deflection and absorption is a primary function of breakwaters. This function is affected by the type of facing material, face slope, structure height, water depth, and wave climate at the site. A breakwater must be designed and constructed to allow breaking waves to expend their energy over a large area rather than a single point (Coen-Cagli 1932). The outer slope of a breakwater should be a low angle. The crest should reach a height which either prevents overtopping by the design wave or allows only a preplanned amount of overtopping. The design should also include provi- sions to prevent piling up of water be- hind the structure and to prevent trans- mitted waves from damaging facilities behind the breakwater. The required width and height of a breakwater rela- tive to the height and wave length of the design wave are discussed by Saville et al. (1965). The conventional rubble mound or rock construction is most typ- ical, although numerous other designs have been employed with varying degrees of success (Figure 9). Floating breakwaters are sometimes a functional alternative to fixed struc- tures, but they have some unique design criteria. Unless they are designed to be constantly in motion, some sort of an- chor is necessary. Piles or other anchor devices are generally placed on the bot- tom with lines, cables, or chains at- tached to the floating structures (Fig- ure 10). These anchor lines should have a tested strength at least twice that of the design load and should be as nearly horizontal as possible (Killer 1974b). Most breakwaters protect waterways, consequently, their siting is dictated by the configuration of the shore and by the desired harbor design. Many existing breakwaters are in the worst possible locations as far as obstruction of lit- toral drift is concerned (Snodgrass 1964). In the future, design modifica- tions and breakwater locations should cause minimal disruption of longshore transport. Cn relatively shallow, 30 ft (9 m) or less, open shorelines, fixed breakwaters are considered the better choice (Seymour and Isaacs 1974). Float- ing breakwaters interfere less with sand movement, water circulation, and fish habitat and are preferred for temporary installations in deep water, or where bottom conditions are unsuitable for placement of a fixed structure (Miller 14 < < LU ca O LU CO uj t— < < LU to O •a c ro 01 c o 1/1 c OJ to S- oj +J s n3 QJ S- XI xi XI ■(-> oj Dl S- * oj E Q oj J LU CO T3 < LU • <-0 "O to OJ C Ol O S- T- 0) +J ' e 1- XI 13 3 C 00 O pi ca 1 site c >> +-> S- <*- r— O 3 O 2 T- OJ +-> •1- S- > W Q. rtJ >> C XI ctio ned CU -i- to S a: 1 S- UJ 00 at >- 00 4-> < 0 aj S- T3 — > c_> a> OJ S- LU • ra t— 00 to ai 1— LU S_ •!- ^ u CX> +■> •1- OJ U- TO 15 >* o >■> CO cu <— +-> r— S- QJ 3 5 O o T3 CU -£= E Q- S- fO o s- 4- CD S_ O cu +-> a. o to Q- C CD cn +-> •r— 'r— CO CO <1) CO -o co ai •i- o S-.CS- a> +-> 3 +-> o to - 2 ro cu +-> rO CU «3 M -C ^ I +-> CD M- -.- 4- O N O I— c c rtJ O CU C M- E O CO +J •r- O 4- +-> s- s- <=> c: cu - o -c c O +-> ra c i- ra 4- -C CO O •r- -O •!- X (US I— a. Q.4- O O • 4-> cti co ai +-> co ra cu S_ -C Z3 CT1T3 CU •r- C -C u_ 16 o < O CO \ \ < < CO C LU > < ro +-> a; TD ■a ro to e o to CD to OJ QJ CD S- -Q • CD to +J cz o ro • r— +-> 4- • r— O -D C ■5 o a> (J •t— > QJ +J i — -r— , — u 3 cu (J i/» •r— i +J to S- 00 ro r> a. S- C-J >^ JD • -a o QJ 1 — e •p— QJ | 3 QJ ai4-> •r— QJ Ll_ T3 17 1974b) . If disruption or obstruction of littoral drift is unavoidable, provisions must be made to allow for bypassing sand to avoid starvation of downdrift beaches and shoaling of waterways. Breakwaters are used for shore protection either with other structures (e.g., revetments, seawalls, groins) or as an alternative to them. Steep shore- lines and sandy beaches can be protect- ed and sand accretion can be caused or enhanced by breakwaters. Sometimes a breakwater is placed in the intertidal or subtidal zone as an erosion prevention device (Figure 9). Maintenance requirements must be considered when choosing a breakwater design. Floating breakwaters are more vulnerable to extensive wave action and often require more frequent maintenance than fixed structures. Vertical face breakwaters must be thick or firmly braced, or high waves will damage them. Rubble mound structures can generally withstand extensive wave action, but are vulnerable to erosion at the toe, particularly at breaches and ends which can lead to a slope failure (Savffle et al. 1965). Overtopping waves can dis- lodge cap rock. Extended storms can disarrange facing stones and cause slumping or structural failure. Sub- merged rubble mound structures with well-chosen facing material probably re- quire the least maintenance of all types (Saville 1960). The physical effects of construc- tion and presence of a breakwater must be considered in design and location. These effects are discussed in the Sum- mary of Physical and Biological Impacts section. Design of long-lasting, func- tional breakwaters is not a simple pro- cess. A thorough discussion of design criteria of rubble mound breakwaters is found in Saville et al. (1965). Socioeconomic. Offshore fixed breakwaters tend to be more costly than shore-connected structures, partly due to the problem of transporting the con- struction materials offshore and partly due to the logistics of maintenance(U . S. Army Corps of Engineers 1973b). A less costly breakwater is the scrap tire artificial reef. Usually placed to provide an artificial fish habitat, it can also function as a breakwater. They are inexpensive and are considered a good method of disposing of used tires (Alfieri 1975). Floating breakwaters are also generally less expensive to build and maintain than fixed structures, but provide substantially less wave attenua- tion (Seymour and Isaacs 1974). The cost of shore-connected fixed breakwa- ters compares with that of jetties of similar size. Low or submerged offshore break- waters are usually unobtrusive and do not interfere with aesthetic enjoyment of the shore. Their visual impact is low, and they are usually far enough from a beach that they do not interfere with recreation (Cole 1974). In some cases, their presence can contribute to the at- tractiveness of a beach since they serve to attenuate incoming waves and provide a sheltered, low wave energy area for recreation. However, construction activ- ities may hamper recreational use of the shoreline to a considerable degree, and the presence of a breakwater may lead to changes in shoreline topography. These changes could be either beneficial or detrimental to recreation. The con- struction of a breakwater can cause secondary impacts, such as changes in use patterns and accumulation of litter. Breakwater-associated restrictions on future public use of an area should be considered before the structure is plac- ed. Biolooical. Fixed breakwaters are subject to the same biological placement constraints as jetties, groins, revet- ments, and bulkheads. Riprap or durrp- ed stone faces are biologically more de- sirable than flat faces since they pro- vide more habitat for aquatic species. Sloping faces are preferable because vertical faces lack the shallow water zone and create less hard bottom sub- strate. Breakwaters should not be al- lowed to interfere with fish migratory runs or spawning areas (Persaud and Wilkins 1976). The base of the break- waters should be protected so that scouring does not affect structural integrity and, therefore, the aquatic organisms in the area. Construction activities should be 18 timed to avoid fish spawning and migra- tion seasons, and times when birds are nesting in the vicinity of the construc- tion site. Turbidity control devices should be employed whenever possible, and associated dredging should be mini- mized to avoid damage to the biota( Flor- ida Department of Natural Resources 1973). Shellfish habitat and other areas rich in plant and animal life should be avoided. Hopper dredges seem to cause the least damage to the biota (Thompson 1973) and should be favored over hy- draulic dredges. However, the use of hopper dredges is usually limited to the construction and the maintenance of en- trance channels. Construction Materials Breakwaters can be constructed from a wide variety of materials. Gen- erally, these can be classified as rock, wood, concrete, metal, rubber tires, filled bags, and rubber-type synthetic materials (Table 1). Almost any material possessing structural integrity could be used in breakwater construction. The lifespan of breakwaters de- pends greatly en the construction mate- rials. For this reason, preliminary mate- rial testing is necessary, both of physi- cal characteristics and ability to with- stand wave action. Tests of stone, for example, should include specific gravity, abrasion, slaking, freeze-thaw, and other relevant examinations (Allison and Savage 1976). Granites or basalts are preferable to limestone, due to the Tat- ter's tendency to abrade readily and to lose weight by dissolution of solids. If concrete is used, it should be alkali-re- sistant. Metals should be galvanized or coated to resist corrosion and wood should be treated with chemical preser- vatives. Whatever materials are used, they should be chosen on the basis of breakwater components being adaptable to substitution, ability to resist corro- sion and abrasion, durability, and cost- effectiveness (U.S. Army Corps of Eng- ineers 1973b). The most common facing material seen on breakwaters along the United States coastlines is rubble, rough stone, or precast concrete in a variety shapes (Figures 5 and 11). The size, weight, and random or patterned placement of rubble components must be determined by individual site studies. Other facing materials include steel or concrete sheet piles, timber, and gabions, which are rock-filled wire baskets (U.S. Army Corps of Engineers 1973b). Core material is usually chosen on the basis of its permeability and whether an individual structure is designed to be permeable or impermeable. The cap, if included, is generally of rubble or precast concrete (U.S. Army Corps of Engineers 1973b). Expected Life Span Data are not available concerning overall life spans of breakwaters. How- ever, periodic maintenance can be ex- pected to prolong a structure's effec- tiveness. Floating breakwaters are gen- erally not as long-lived as fixed ones. Breakwaters are constructed of materials similar to jetties; thus, some compari- sons can be made concerning lifespan. Rubble mound structures, if repaired when unit displacement is severe, can last up to 50 yr (U.S. Army Enqineer District, Portland 1975b). Steel," con- crete, and timber structures should last up to 35 yr, depending on site-specific environmental factors (U.S. Army Corps of Engineers 1973b). Lifespan also de- pends on the severity of the design wave for a particular structure relative to the wave environment it will actually encounter (Saville et al. 1965). Summary of Physical and Biological Impacts Construction effects. Physical ef- fects from placement of breakwaters are similar to those for jetties, groins, piers, and other structures in the near- shore areas. Rock dumping, jetting or driving piles, dredging to a solid bed or required depth, or any other con- struction-associated activity which dis- turbs the bottom sediment increases tur- bidity (U.S. Army Engineer District, Seattle 1971) and can impact bottom dwelling aquatic organisms, remove sub- merged vegetation beds, drive away fish and other mobile organisms, and alter the existing habitat at the structure site (Morton 1976, Cronin et al. 1971). Some degree of noise, air, and 19 Table 1. Materials used in breakwater construction as determined from the literature. Fixed breakwaters Floatinc breakwaters Pock Broken quarry stone Basalt Limestone Coquina k'OOd Creosote-treated timbers Copper chromium arsenate- treated timbers Chenonite-treated timbers Pent achl oral phenol -treated timbers Concrete Pour-in-place Preformed Prestressed Concrete rubble Metal Steel (galvanized or coated) Stainless steel Aluminum alloy Wood Chemically-treated timber Plywood Concrete Cement reinforced with glass fiber Prestressed concrete Metal Steel sheet Steel tubing Aluminum al loy Elastomeric material Molded polyurethane Rubber floats Plastic floats Fiberglass Polystyrene Ti res 20 Figure 11. Tribar, a precast, reinforced concrete structure used as facing on breakwaters and jetties. Photograph courtesy Portland Cement Association. 21 water pollution inevitably accompanies construction activity. Petroleum pro- ducts in minor quantities seep into the water from construction equipment and the exhaust emissions add hydrocarbons to the air (U.S. Army Engineer District, St. Paul 1976a). Turbidity can clog gills of fish and other organisms. Toxic materials and silt suspended by con- struction activities can have a detrimen- tal effect on the biota of the immediate area (Morton 1976, Cronin et al. 1971). Turbidity effects are most significant upon juvenile stages and sessile organ- isms. ' The dislodging of organisms can cause a feeding spree by predators dur- ing construction periods. Maintenance effects are much the same as those resulting from construc- tion, though often less severe. Break- waters are constructed in high-energy environments which are often character- ized by sediments with fairly large par- ticle size. Larce particle-size sediments are less likely to cause turbidity or tox- icity effects than are small particle-size sediments characteristic of lower energy environments. Chronic effects. After construction is completed, a new situation exists both at the breakwater and within the pro- tected zone. Wave energy is much re- duced inside the breakwater (Ortolano and Hill 1972). A fixed breakwater can cause piling-up of water behind it, de- crease circulation, interfere with tides and currents, and obstruct littoral drift (Clark 1974, Sanko 1975). If the break- water is shore-connected, particularly if it has a shore-parallel leg, the effect on littoral drift can be severe. Piling-up most frequently occurs behind breakwaters that have restricted openings. This leads to a higher water level behind the breakwaters than out- side (Diskin et al. 1970). Differences in the water levels result in accelerated flows at the openings or ends of a breakwater. The resultant toe scour at the base of the structure can cause both local turbidity and damage to the structure (Saville et al. 1965). Because of lower wave energy and altered current patterns, the lee side of a fixed breakwater can experience de- aradation of water quality and fluctua- tions of temperature and salinity (Had- erlie 1970). Sand tends to be deposited on the shoreline opposite a detached fixed breakwater and immediately updrift of a shore-connected structure (Figure 12). The sand deposition opposite a de- tached, fixed breakwater can form a tom- bolo (a bar or spit that connects an is- land with the shore) between the struc- ture and the shore if the breakwater is long enough in proportion to its dis- tance from the shore (U.S. Army Corps of Engineers 1973b). If conditions are not conducive to tombolo formation, detach- ed, fixed breakwaters can still cause spit formation on the opposite shore- line. This spit then acts as a partial barrier to littoral drift, allowing the sand to deposit updrift and be eroded away downdrift. Floating breakwaters and submerged breakwaters have much less in- fluence on littoral drift (Harris and Thomas 1974, U.S. Army Corps of Engi- neers 1973b). Another problem which can occur within a harbor partially enclosed with fixed breakwaters is the generation of secondary waves. These waves result from reflection within a confined space and can often attain considerable size and energy (Saville et al. 1965). Careful design will usually prevent this situa- tion; but if it occurs, alterations in the existing facilities become necessary (Slawson 1977). Breakwaters constructed from the rock, rubble, and other materials with irregular surfaces provide a rocky surf habitat on the seaward side, and a rocky calm habitat on the lee side (Kowalski and Poss 1975). These new habitats are gained at the cost of the previously existing bottom dwelling organisms. In many situations, the new rocky habitat can be considerably more productive than substrate that previously existed. This is well documented in literature about artificial reefs. The protected water inside a fixed breakwater, with the possible altered fluctuations of temperature, salinity, and water level, can lead to a change in the plant and animal species composition 22 BREAKWATER H 5 SAND ACCRETION .»«• ''^:s -■?-'. •• - v S: n. ■ -.--'v. ■/$■*■*"■'■''■'-'■' •-'■'.' ' "- v.V-Aa V 5? '-.' fc-^'-;' -' -„ ; "• "•-;* -A. A V ' -' ■■.'*;"* -'■•'"• '-'V V"- -'.'"-V- v' ^v --*■_', ;. : - . ■ ;: . , . - - ■ - - - . . . CV . .■■:; ORIGINAL SHORELINE' "" : ;/' ' : DETACHED EMERGENT BREAKWATER DIRECTION OF TRANSPORT ► NET LONGSHORE BREAKWATER SAND ACCRETION \> ^"""ADDITIONAL -JiVA SHOALING ■BREAKWATER iv-^r ORIGINAL SHORELINE *m&m ''<%&, -..* "*V POSSIBLE -i/^y" - '. EROSION^ -.,y.>;, - ATTACHED BREAKWATER Figure 12. The dotted lines show typical areas of erosion and sand accumula- tion behind attached dogleg and detached solid breakwaters. The sand formation behind the offshore breakwater is called a tombolo. 23 with sensitive taxa being replaced by those with a wider ranee of tolerance (G if ford 1977). Breakwaters are func- tionally located in high-energy environ- ments that are usually typified by rath- er coarse sediments. The area seaward of a breakwater would be expected to develop a coarse-sediment environment, especially if compared to the previously existing deeper bottom, a low-energy environment. The enclosed area land- ward of the breakwater will, in many cases, develop a sediment composition that is less coarse than previously existed. This shift in sediment type will cause concomitant shifts in species distribution, diversity, and numbers. These shifts can be either beneficial or detrimental. The creation of a new type of bot- tom often results in replacement of a deepwater fish habitat with a shallow shellfish habitat (Snow 1977). This will depend upon the biology of the area where the breakwater is constructed. If sand deposition creates an emergent or intertidal sandbar, then a new type of bird habitat may result. The stone surface upon and behind the breakwater may be used by birds. The sandbar and rock habitats are preferred by the gulls, terns, and other beach-dwelling species. Colonial nesting may occur if human disturbance is limited during nesting season. Breakwaters can affect longshore fish migration routes. This has been documented for salmonid fry where the presence of a shore-connected breakwa- ter forced them into deeper water than previous conditions afforded (Stockley 1974). The reduction of shallow water areas decreased the available salmonid fry migration routes. The fry were ex- posed to increased predation because they would not migrate around the structure. The effects of floating break- waters are generally less severe and the Washington Department of Fisheries (1971) strongly recommends their use to protect fish resources. Water circula- tion is only slightly affected, and the piling-up of water behind the floating breakwaters is negligible because they are anchored by cables or widely spac- ed piles (Kowalski 1974b). Installation causes much less disturbance of bottom habitat, though any setting of piles or permanent anchor blocks would cause some minor suspension of sediments. Once in place, floating breakwaters provide a substrate for fish, algae, and sessile organisms. They interfere only minimally with fish migration. By shad- ing the bottom, floating breakwaters can reduce productivity, but the prolifera- tion of attached organisms and the graz- ers which they attract may balance or offset their reduction (Gifford 1977). Cumulative effects. Very little information was found on the cumulative effects of breakwaters or breakwaters in combination with other structures. If two or more fixed structures are placed in proximity, the resultant alteration in current patterns could cause scour damage to one or more of the structures. The location of structures close to each other can cause other synergistic ef- fects: littoral transport modifications, alterations of wave energy environments, and alterations of water quality parame- ters, such as salinity and dissolved oxygen or the concentration of petro- chemicals. The degree of such changes must be evaluated case-by-case. Structural and Nonstructural Alternatives Breakwater design is a function of the shape of the structure or area to be protected, and the direction and sever- ity of the wave attack. Given these two conditions, the breakwater cross-section and construction materials will be se- lected on the basis of materials avail- ability and cost minimization. There are several possible alternatives to propos- ed breakwaters. It is possible to dispense with the breakwater and devise other means to deal with the wave attack on the harbor or structures. The higher wave climate could be dealt with by increasing the structural design of piers, floats, ves- sel mooring systems, and other features of the harbor. This response is gener- ally more feasible in harbors for large ships because small craft cannot take repeated pounding against structures. If the shoreline must be protected, 24 alternatives to a breakwater are revet- ments, seawalls, bulkheads, increased beach cross-section, or other methods. To compensate for reduced water circulation and attendant problems in- side a basin protected by a breakwater, a permeable breakwater or floating breakwater could be substituted for a fixed, solid structure. Floating break- waters have the additional advantage of being portable and, to some extent, re- usable. In shallow water areas not subject to severe wave attack, vertical wood pile or sheet pile structures are often used as breakwaters. If rock is avail- able, a low, rubble mound structure may prove equally effective and econom- ical, while alleviating some of the envi- ronmental problems associated with fixed breakwaters and vertical surfaces. When the breakwaters are used to create a basin, there is usually a shape that will minimize the total cost and re- duce the dredging required for the ba- sin. Placing the basin in deeper water may increase breakwater costs, but de- crease dredging costs. The reverse is also true. Assuming there is no problem with property ownership or rights, the shape of the basin can be altered to achieve a different balance between breakwater and dredging or between development of water area versus land area. Regional Considerations Breakwaters are found at virtually every harbor and estuary on the north Pacific coast (Coastal Region 1). They are primarily intended to protect water- ways from extensive wave action. The State of Washington has outlined strict guidelines for their design and place- ment. These include the following phy- sical placement criteria: at least two gaps must be provided to allow water circulation and flushing; the structures must be less than 250 ft (69 m) from MHHW (mean higher high water) line and not be below 0 ft MLLW (mean low- er low water); facings must be perman- ent material and stair-step design; the openings must not be shallower than the dredged enclosure. Vertical faces are considered undesirable because they pre- clude a shallow water area, while 30-de- gree slopes approximate natural condi- tions.Though raw earth or gravel facings are similar to the normal habitat of juvenile salmon, they allow erosion and damage shellfish beds (Washington De- partment of Fisheries 1971). Limited data are available concern- ing altered environmental conditions. Algae and hydroids have been noted on breakwaters in Puget Sound (Millikan et al. 1974, Smith 1976) and fish were abundant at one breakwater (Smith 1976). Smith (1976) also reported three dis- tinct zones of marine invertebrates along a breakwater. Ricg and Miller (1949) observed surf habitats on the outer face of a breakwater and typical quiet water types of sessile organisms on the inner face. They also observed an unexplained abundance of starfish at one breakwater. Millikan et al. (1974) noted large amounts of herring spawn on evergreens submerged in the vicinity of breakwaters; flocks of scoters fed heavily upon the spawn. Physical impacts, as described in the general section, were expected to re- sult from the construction and presence of breakwaters on the north Pacific coast (Coastal Region 1). The major bio- logical impact discussed was upon salmo- nid fry which became vulnerable to pre- dation due to an interference with mig- ration (Richey 1971). In some cases shellfish beds were destroyed by break- water placement, but in others new clam beds were established in sand accretion areas. Shoaling around one breakwater was expected to alter benthic habitat, preclude bottom use by fish and shell- fish, and create additional bird habitat (U.S. Army Engineer District, Seattle 1971). However, Rigg and Miller (1949) reported that another breakwater in Puget Sound had no noticeable effect on organisms in its vicinity after 10 yr. Most of the breakwaters in southern California (Coastal Region 2) are asso- ciated with harbors, often small boat moorages. In a few cases, detached off- shore breakwaters function as shore pro- tection structures. Both shore-connect- ed and detached breakwaters can be found in this region, and most of these are 25 constructed of rubble mound. Physical impacts from breakwater construction and presence are similar to those pre- viously described. Deterioration of water quality is frequently a problem in breakwater protected harbors (Slawson 1977, Carlisle 1577). Red tides (dino- flagellate blooms) are severe in most harbors in the Los Angeles-Long Beach area (Slawson 1977) and probably occur frequently wherever circulation is im- paired. Breakwaters in the Gulf of Mexico (Coastal Region 3) are used both for shore protection and in harbor areas. They are placed either parallel or per- pendicular to the shoreline. Most act as littoral drift barriers and require modifications to bypass sand. Construc- tion materials are rock, concrete, sheet piling, timber, and scrap tires. Scrap tire breakwaters are being developed for protection of the Florida coastline (McAllister 1977). Breakwaters are less common than groins in south Florida (Coastal Region 4). Most of the existing ones are part of small boat harbors. A large portion of south Florida is characterized by nat- ural offshore reefs and is also somewhat protected by the Bahamas (McAllister 1977). Floating breakwaters often at- tract marine animals and is one case a community of marine invertebrates and fish was well established on a floating breakwater within a month of its place- ment (G if ford 1977). No unique information concerning breakwaters in the south Atlantic (Coastal Region 5) was found. Physical and biological impacts were similar to those desribed for other regions. Sandbag sills (sand-filled nylon tubes or lines of sandbags) were the only type of breakwater for which in- formation unique to the middle Atlantic (Coastal Region 6) was found. These are utilized to prevent erosion of indi- vidual waterfront lots or to improve the effectiveness of a groin system. They are placed much farther inshore than most breakwaters and are considerably smaller than the usual breakwater. Placement is in the subtidal zone, just below mean low water, on sand beaches with complex patterns of littoral trans- port. Physical and biological impacts are expected to be insignificant though no quantitative studies have been made. Unless well marked, they may be a navi- aation hazard to small craft at low tide. Little information was found con- cerning breakwaters in the north Atlan- tic (Coastal Region 7). Breakwaters are frequently used in the Great Lakes (Coastal Region 8) for shore and harbor protection. Most are shore-parallel and detached. Construc- tion materials include many of those listed in Table 1. One rather unusual design is that of a steel or concrete zig-zag wall parallel to shore with its crest just above mean water level (Fig- ure 9). One physical impact of break- waters which is unique to the Great Lakes is the enhancement and prolonging of harbor icing. Protected water behind breakwaters ices over earlier in the fall (U.S. Army Engineer District, Buf- falo 1975a) and remains frozen longer in the spring. JETTIES Definition "A jetty is a structure extending into the water to direct and confine river or tidal flow into a channel and to prevent or reduce shoaling of the channel by littoral material. Jetties, located at the entrance to a bay or riv- er, also serve to protect the entrance channel from wave action and cross cur- rents. When located at inlets through barrier beaches, they also stabilize the inlet locations." (U.S. Army Corps of Engineers 1973b). The most common type of jetty is one extending into the ocean at the en- trance to a bay or river (Figure 13). However, training works (including train- ing walls) located in estuaries and along rivers to guide currents and as- sist in channel deepening are also com- monly called jetties. Sometimes a struc- ture placed in a river or on an estua- rine beach to direct currents and stabi- lize the beach is called a jetty or a groin (see Glossary) . 26 • >< >> OO CD +J s_ =3 o o J= Gi- ro S- Cn O -t-J O -SZ Q- C o en CD S- o * c o ■a c re ca • C ** o i_ en cu CO > <- •r— O CC «i CO -a 1 — c 1 — ra •1 — f— =3 4-> CT t- O o <_> Q_ >4- „ o +-> O -C ■ r- +-> S- 3 -I-' o l/> E •r— Q +J r0 S_ QJ 00 CU CU c •r- • 1 — +j en +-> cz > E • i- CO 3 O Q- -i-> -a c • c: 3 c o o o s_ •!- CD CD en C J^ '1- •f- (J > IOH D 4- c o O) •!- •!- > 4- •r- >,-.- +->+-> •>"D s_ xr+-> Q--t-> 3 s- o o uo TO CD l/l O) +-> S- i— O o s- <_> io ♦» >> >, ifl m E ai cq s- to +-> o -o • i — r — OO O O • d n r> E 3 4- • HT O i— C >> •i— l/) CD 0) S- >>-M 3 +J 4- CD +-> 3 •i- O 30 sloped sides and protect the base of the structure from scour and undermining (U.S. Army Corps of Engineers 1973b)' Sheet piles are not satisfactory in high wave energy environments, but can be used where the wave climate is less severe. Steel, used as sheet piles, should be coated to prevent corrosion. Timber must be treated with preserva- tives to prevent attack by marine inver- tebrates, such as borers and gribbles. Concrete is immune to pests, but an im- proper mix can deteriorate rapidly in seawater (U.S. Army Corps of Engi- neers 1973b). Expected Life Span Rubble mound jetties can last up to 50 yr if properly designed and main- tained (U.S. Army Engineer District, Portland 1975b). Maintenance includes both replacing displaced armor compo- nents after particularly severe storms and major repairs every 15 to 20 yr to replace broken, worn, or lost compo- nents. Sheet pile jetties, whether steel, timber or concrete have shorter life- spans due to abrasion by sand and wa- ter-borne debris, corrosion by salt wa- ter, and attack by borers or gribbles (U.S. Army Corps of Engineers 1973b). They can last anywhere from 10 to 35 yr depending on the conditions of their environment. Summary of Physical and Biological Impacts Construction effects. As with any major construction activity in the coast- al zone, placement of jetties causes some temporary disturbance, such as turbid- ity caused by res us pension of bottom sediments. Toxic substances present in sediments can be released (Carstea et al. 1975a). Noise, and air and water pollution will accompany construction activities (U.S. Army Engineer District, St. Paul 1976a). During construction, nearshore currents can be disrupted. Erosion and accretion can occur locally in patterns quite different from those previously existing or those which de- velop after completion (Anderson 1975). Suspended sediments may reduce pri- mary productivity and smother benthic organisms (Cronin et al. 1971). The area covered by the jetty will be lost as a bottom habitat (Virginia Institute of Marine Science 1976), but a new type of habitat will be created. Chronic effects. The presence of jetties at a river or bay mouth alters both river outflow and tidal currents (U.S. Army Engineer District, Portland 1975b). These alterations are often felt well into the estuary and may have wide- spread effects. Altered rates of nutri- ent and sediment accumulation can occur in salt marshes. Salinity and tempera- ture changes can occur. The tidal prism can be altered since overall circulation patterns within an estuary are affected by the change in water flow through a stabilized channel. The flushing charac- teristics of the estuary can be changed and wave height often increased in its lower regions (Carstea et al. 1975a). Outside the estuary, the most sig- nificant effect of jetties is the alter- ation of littoral transport. Littoral transport is obstructed by the jetties; sand is impounded updrift and eroded downdrift. If a single jetty is install- ed, the opposite side of the inlet can erode severely. Also, a shoal can form at the tip of a single jetty updrift of an inlet and eventually fill in the in- let. The influence of a jetty extends well beyond its immediate vicinity. Downdrift beaches retreat due to sand starvation unless measures are taken to bypass the sand that accumulates updrift of the jetties (Ketchum 1972). Changes in foredune height have been reported downdrift of jetties (Demory 1977). The channel formed by jetties often migrates from the original location to an area adjacent to one of the jetties, scouring the bottom and causing turbidity. As the channel nears the jetty, the scouring action can erode the base of the jetty and necessitate re- pairs or strengthening of the structure base. Sandbars tend to migrate seaward in the presence of jetties (Kieslich and Mason 1975). Dredging is usually requir- ed to maintain a channel of sufficient depth since the tidal currents are inad- equate to keep the channel scoured (U.S. Army Corps of Engineers 1973b). The placement of jetties destroys 31 some bottom habitats and creates new ones. Rubble mound structures provide attachment sites for sessile organisms, and the irregular surface can support a diverse community of rocky shore plants and animals (Ortolano and Hill 1972). Sand accretion areas can provide new habitats for shellfish and shorebirds (Snow 1977). Areas where erosion takes place often become populated by fish which require deeper water. Jetty relat- ed fisheries can develop (Ortolano and Hill 1972). However, the presence of jetties may limit or alter the normal movement of fish and crustaceans into and out of estuaries (Cronin et al. 1971). Physical changes in water circu- lation, flushing, current patterns, and shoaling within the estuary may severe- ly degrade or alter existing habitats (U.S. Army Engineer District, Portland 1975b). In some cases altered circula- tion patterns are beneficial. Cumulative effects. Most of the effects due to jetties are noticeable in the immediate vicinity and in the em- bayment or river and coastal area where they are constructed. There is gener- ally little reason to construct several pairs of jetties in proximity. Therefore, cumulative effects due to proliferation of jetties are not obvious. It is possi- ble, however, that numerous jetties along a coastline could have the same cumulative effects upon littoral trans- port as a numer of groins could. Structural and Nonstructural Alternatives Jetties are normally used to pro- vide channel or inlet stabilization and to reduce the amount of dredging required to maintain the inlet or channel. There are different materials and configura- tions available for jetty construction. It is also possible to use other structures, such as groins, in conjunction with jet- ties to reduce or modify effects of the jetty on adjacent areas. Nonstructural alternatives fall into two categories. The first is to do noth- ing and forego the use of the waterway for navigation and possibly adjacent lands for some form of development. The second alternative is to maintain naviration by means of dredging. This alternative can be very costly and can result in the channel being unusable for certain periods due to the inability of dredging equipment to provide and to maintain desired depths for navigation. It is also possible that the dredging and disposal process will have an impact on the surrounding environment which is far greater than the impact due to jet- ties. Regional Considerations Jetties have been built, or are planned, for virtually every inlet of significant size in the North Pacific (Coastal Region 1). In some cases only a single jetty has been placed but most inlets are stabilized by a pair of jet- ties. All are placed perpendicular to the shore and are of rubble mound or quarried stone construction. No unique placement constraints apply to this coastal region. Construction materials include rock (usually basalt), quarry stone, and, in at least one case, dolos- se. Average life span of jetties in this area is about 50 yr with major repairs expected to be necessary during that period (U.S. Army Engineer District, Portland 1975c, 1976e). Long-term impacts include erosion and accretion changes, habitat altera- tions at the jetties and within estuar- ies, and changes in tidal patterns and water quality. Storm waves have caused severe damage to jetties as a result of scouring (Wong 1970). A number of sand spits have been altered, breached, or destroyed as a result of jetty-caused current changes. The foredune at Tilla- mook,Oregon, is many times higher than it was before construction of the Tilla- mook jetty. No summer return of winter sand loss was observed in the first few years following extension of Yaquina Bay, Oregon, jetty (Demory 1977). Jef- ferson (1974) reported that configura- tion of some of Oregon's coastal bays has been changed by the construction of jetties. All" along the Oregon coast, changes in habitat, apparently connected with presence of or changes in jetties, have been observed (Snow 1977). In one case, a jetty's influence on littoral transport contributed to the breaching of a sand spit. This allowed sand and boulders to enter a protected lagoon and 32 bury most existing commercial oyster beds (Jefferson 1974). Jefferson (1974) also blames jetties for contributing to modification of estuarine salt marsh habitats. Jetties are commonly found at coastal inlets throughout southern Cali- fornia (Coastal Region 2). In several cases, they are associated with man- made harbors (Reish 1962). Rubble mound construction utilizing rock is most common. No placement constraints are unique to this coastal region. Sea mussels, barnacles, limpets, snails, and other sessile and cryptic organisms pop- ulate most of southern California's jet- ties (Reish 1964). A green algae, Ulva dactylifera, is a pioneer species on new- ly constructed jetties (Reish 1969) and is soon joined by a variety of marine animals. No unique construction related physical or biological impacts were iden- tified for Coastal Region 2. Long-term impacts were similar to those previously described. Jetties in the Gulf of Mexico( Coast- al Region 3) are placed in inlets in bar- rier islands, as well as at river mouths. Placement constraints are those previ- ously described. Most are rubble mound structures constructed of stone, includ- ing granite. Varying salinity and cur- rent regimes often exist on opposite sides of jetties, and if the structure is hooked to protect a harbor, there may often be varying wave climates inside and outside (Gifford 1977). Jetties pro- vide a habitat for sessile and cryptic organisms that attract fish and birds. The physical and biological impacts of jetties have been described previously. In addition to those described, Hastings (1972)reported that fish from more trop- ical areas were found in the vicinity of jetties. On the channel side of jetties, the organisms tend to be those with a greater tolerance for the rapid salinity changes, periods of low water clarity, and strong tidal currents while those on the outside were tolerant of surf condi- tions (Hastings 1972). Hastings (1972) further reported that most fish found near jetties were secondary consumers. Jetties are common in south Florida (Coastal Region 4) and are found at in- lets and harbor mouths both on the mainland and on barrier islands. They are used to stabilize inlets, train cur- rents, and protect beaches. Lying per- pendicular to the shoreline, they extend beyond the surf zone. Placement con- straints are those generally applicable to jetties everywhere. However, the Florida Department of Natural Resources (1973) has pointed out that jetties are not permanently successful in fulfilling their function unless they are integrat- ed with other shore protection measures as part of a comprehensive program cov- ering large stretches of shoreline. No physical or biological impacts unique to this coastal region were found. No data were found that were unique to jetties in the south, middle, or north Atlantic (Coastal Regions 5, 6, or 7.) Jetties in the Great Lakes (Coastal Region 8) are often constructed of mate- rials other than rubble mounds. Steel sheet pile cells, cassions, and timber, steel, or concrete cribs are also uti- lized. Timber and steel sheet piling in single rows are sometimes used in shel- tered areas (U.S. Army Corps of Engi- neers 1973a). GROINS Definition A groin is a rigid structure built out at an angle (usually perpendicular) from the shore to protect it from ero- sion or to trap sand. A groin may be further defined as permeable or imper- meable, depending on whether or not it is designed to pass sand through it. Groynes (British), spur dikes, and wing dams are included in this defini- tion. Sometimes the word jetty is used interchangeably with groins; however, jetties generally have a different func- tion. Under certain conditions a struc- ture may be carrying out functions nor- mally associated with both jetties and groins. An example would be directing stream flow in a river, while concurrent- ly stabilizing a beach. Structure Functions The most common function of a groin 33 is to provide or maintain a beach. Groins can be designed in various con- figurations to do any of the following: o build or widen a beach by trap- ping littoral drift; o stabilize a beach by reducing the rate of sand loss; o prevent accretion in a downdrift area by acting as a littoral bar- rier. The above functions all assume existence of either a sandy beach and/ or a littoral supply of sand. Groins can affect areas both updrift and dot n- drift. The functions of building, or stabilizing a beach may have the effect of starving an adjoining area. Site Characteristics and Environmental Conditions Groins are constructed on many types of shorelines, but most commonly on shallow, sandy, or shingle beaches. Since they can be used to prevent ero- sion, build or widen beaches, or prevent downdrift accretion, their siting on the shoreline is dictated by their intended function (Figures 15, 16, and 17). For a groin or groin system to function, there must be a supply of sand provid- ed by littoral transport. Other than this common characteristic, no generali- zations can be made concerning environ- mental conditions or groin sites. Placement Constraints Engineering. A groin must be de- signed for a specific site. There is no best design , optimum choice of construc- tion, nor ideal length or spacing between groins that can be applied generally to all situations. The substrate of the site must be studied to determine structural limitations, material availability, and maintenance requirements (U.S. Army Corps of Engineers 1973b). Other char- acteristics of a shoreline must also be known before a single groin or a groin field is constructed. These are angle of wave approach, volume of littoral drift, wave strength, current, and shoaling patterns (Horikawa and Sonu 1968). If the objective of the groin or groin field is to trap sand and to mini- mize sand movement downcoast, groins should be built to a height that will prevent normal high water from carrying sand over them. When continued movement of sand is desired, the height of groins should be near to or below normal high tide level (Balsillie and Eerg 1973). Length of groins is also dependent on the degree of littoral drift obstruction desired and on existing and desired beach slope (U.S. Army Corps of Engi- neers 1973b). Length is measured from the groin's landward end at the berm to its seaward end. The seaward end usually extends to the point where incoming swells exert the greatest force on the sand bottom (Coen-Cagli 1932). The spacing of groins in a groin field is subject to a number of factors. As a general rule, groins should be sep- arated by a distance tv/o to four times their length (Savage 1959, U.S. Army Corps of Engineers 1973b). However, spacing must assure that minimum beach width is maintained. A more detailed discussion of the factors involved in groin spacing is found in the Shore Pro- tection Manual (U.S. Army Corps of Engi- neers 1973b). Though the majority of groins are straight, some are built with a length- wise curve or are L-, Z-, or T-shaped (Balsillie and Berg 1973). Their crests can be level or can slope downwards to- ward the seaward end (U.S. Army Corps of Engineers 1973b). In a groin field, suc- cessive downdrift groins can be made progressively shorter or lower, with the latter variation being preferable (Coen- Cagli 1932). Whatever the design of groins, starvation of downdrift beaches should be prevented. If a newly constructed groin will capture nearly all littoral drift, artificial nourishment is desir- able to assure a supply of sand to down- coast beaches (Sanko 1975). Another method of filling behind a groin in- volves placing a weir or series of weirs along its length. This allows a portion of the littoral drift to continue down- drift (U.S. Army Corps of Engineers 1973b). This structure is effective only if there is no movement of the stone material . 34 -a o o o CD (/> ro -Q CD IS> ■f™ c -C •r- • ^- O > 5- ^— m 3 s: a) +-> • aj _i s- <_> • cz UJ o <_> >. X! . -C m Q. !-• IB S_ CO 03 a) o to o s_ a> C o r~ i — i— CD CO ai s- • 37 It is imperative that groins extend to the crest of the beach berm, or high wave action will cause flanking (U.S. Army Corps of Fngineers 1973b). If the groin extends out from a seawall or bulkhead, it should be solidly anchored to that structure (Coen-Cagli 1932). Socioeconomic. The cost of groins varies greatly, depending on construc- tion materials, anticipated wave action, tidal range, and whether additional beach nourishment will be necessary (U.S. Army Corps of Engineers 1971b). A method of determining economic feasi- bility of groin construction involves comparison of construction and mainte- nance costs with the cost of periodic beach nourishment (Berg and Watts 1971). Prefabricated groins are often economical to install. Timber groins and low permeable structures are probably the most economical for an individual property owner (Horikawa and Sonu 1968, Pallet and Dobbie 1969), Cabion groins (Figure 18) require extensive maintenance. They are also unsightly and vulnerable to damage by drifting logs or other heavy debris. The aes- thetic effects of groin placement should not be neglected. A sandy beach is more attractive than an eroded one. However, the groins that protect it should be as unobtrusive as possible (Coastal Plains Center for Marine Devel- opment Service 1973). Construction activities should not interfere with re- creational use of a beach. Biological. Very little information is available concerning biological con- straints on placement of groins. Carstea et al. (1975a) recommended that restric- tions be placed on the amount of sedi- ment resuspended by construction activ- ities. The effects of groin construction and siting on wildlife propagation and movement should be known and efforts made to minimize adverse effects (Snow 1973). Construction should be planned to avoid interference with fish spawning areas or migratory routes (Persaud and Wilkins 1976). Groins which capture all littoral drift, thus encouraging or ag- gravating downbeach erosion, should not be constructed. Such erosion can degrade aquatic resources. Construction Materials Groins can be built of almost any material which will remain in place and not deteriorate rapidly. Impermeable groins are often constructed of sheet piles supported by piles (U.S. Army Corps of Engineers 1973b). The sheet piles are wood, steel, or a combination. Other materials for impermeable groins include quarried stone, concrete, rub- ble, and asphalt (Figure 19). Permeable groins (Figure 20) are constructed of similar materials, as well as of sand- bags, sand-filled nylon tubes, wood, and earth (Erchinger 1970). Stone groins should have filter cloth under them to prolong the life of the structure by de- laying settling into the substrate. Expected Life Span Recorded life spans of groins vary from 2 to 50 yr. Rubble or quarried stone is reported as the longest lasting construction material, followed by steel (25 yr) , treated wood (20 yr), aluminum (15 yr), and nylon bags (2 yr) (U.S. Army Engineer District, Los Angeles 1974a, Chabreck 1968). All materials vary in permanence, depending on salin- ity, wave climate, and water tempera- ture. Summary of Physical and Biological Impacts Construction effects. Turbidity is a major impact of groin construction (U.S. Army Engineer District, St. Paul 1976b). Resuspension of toxic materials can also occur, as can some noise, air, and water pollution. Compared to jetties and breakwaters, these physical effects should be less because groins are rela- tively small structures. Chronic effects. Groins are intend- ed to prevent erosion or to build the beaches. However, in some cases they contribute to erosion and to beach loss elsewhere that is at least as serious as what they were designed to prevent. A number of cases have been reported where downdrift beach erosion was aggravated. An example of this is described by Pallet and Dobbie (1969) where downdrift cliff erosion was increased by the pre- sence of a groin system. In spite of this problem," groins serve their intend- ed functions. Beaches are stabilized, 38 i- .•-»* £jsg2t% Figure 18. Gabions are used to construct groins on the Great Lakes. Photograph courtesy of State of Michigan, Department of Natural Resources. 39 <1J rtJ ■!-> CD -o C (O l/) C o •r- 10 C c/1 CD o L. c^ • 1/) V c ■ — o -O • r— 10 ■»-> CD • r— E ■o c c QJ o CL u E ■r— CD •t-J C • i— re to 4- s_ O +-> s. CD > -O a T3 CD i — C ■ i — O) E s_ E. 3 CD cn+-> •r— CD U_ T3 40 Figure 20. Prefabricated permeable groin. This component has also been used in the construction of breakwaters. Photograph courtesy of Portland Cement Association. 41 fore dunes are protected, and beach width can be increased by careful placement of groins (Berg and Watts 1971, Pallet and Dobbie 1969). Down- drift beach starvation results when groins completely obstruct littoral drift. Downdrift beaches will recede until the groins are filled and sand bypassing occurs (Schijf 1959). If groins are used to widen beaches, they can be filled with sand after construction thereby lessen- ing the potential impact downdrift. Among the problems that accom- pany groins is scour on the lee side. This can often be minimized by includ- ing weirs along the length of a groin or by making the structure permeable (Horikawa and Sonu 1968; U.S. Army Corps of Engineers 1973b). The appearance of a shoreline on which groins have been built changes from one with long, fairly straight stretches of sand to one with a series of indentations downdrift of each groin. This is due to pattern of erosion and accretion caused by the alteration of longshore drift (Horikawa and Sonu 1968). If the structures are permeable, this recurring series of arcs is less pronounced than if they are imperme- able. The accretion of sand behind groins buries those bottom organisms which cannot move away from the area. However, this disadvantage is usually offset by the increased sand surface area provided (Ortolano and Hill 1972). The surface of groins serves as an at- tachment site for sessile organisms (Cronin et al. 1969), and groins often provide a protected area for establish- ment of beach vegetation (Garbisch et al. 1975). Groins also attract fishes and often provide excellent fishing spots. Before a stable shoreline is achieved, scouring and filling around groins af- fects productivity by keeping the water turbid and by providing a poor habitat for marine plants and animals (Cronin et al. 1969, Garbisch et al. 1975). Cumulative effects. Cumulative ef- fects of numerous groins in an area are similar to the summation of effects caus- ed by single groins. They are, however, more widespread. Because oroins tend to accelerate downdrift beach erosion by reducing the amount of sand transported to them, the placement of one qroin often leads to the need for another a distance away. A series of groins will take longer to fill, prolonging the pe- riod in which downdrift shorelines are exposed to erosive factors. Structural and Nonstructural Alternatives The function of groins is either to stabilize a beach by preventing movement of sand, or to trap littoral sand which would otherwise move past the area under consideration. There are few alterna- tives available which will accomplish these functions. The most obvious is an offshore or parallel breakwater which, by diminishing wave energy, will disrupt the movement of sand along the beach and thereby cause an accumulation of sand in the lee of the breakwater. Besides the immediate function of the groin, two other purposes are imme- diately apparent: o to provide a wider beach for aes- thetic or recreational purposes; o to provide a wider beach to pro- tect land or structures landward of the beach. Both of these objectives can be ac- complished by the nonstructural alterna- tive of beach nourishment. The beach is built up by artifically adding sand from offshore or onshore sand sources. There are numerous examples of this construc- tion practice, particularly along the east coast of the United States. " This process is generally a continuous one since the forces that eroded the beach initially are probably still at work and will erode it after nourishment. Thus, further nourishment is required at a later date. If the purpose of the wider beach is for protection, there are several structural alternatives available. A breakwater will tend to widen the beach in its lee. It will also assist in dis- sipating energy from wave attack, thus providing protection to structures or land in its lee. If the purpose of the 42 wider beach is simply shore protection, and the wider beach serves no other functional purpose, then the upland area can be protected by means of re- vetments, bulkheads, or seawalls as alternatives to groins. The negative impact most often associated with groins is their tendency to starve downdrift beaches of littoral sand. An offshore breakwater will have this same effect so it does not repre- sent an attractive alternative if down- drift starvation is to be avoided. Direct armoring of the shoreline by the revet- ments, bulkheads, or seawalls can have some effect on shorelines immediately downdrift; but the impact will normally be less than that of groins. Of course, these structures will have impacts of their own which are described elsewhere in the report. Artificial beach nourishment by dredging or truck hauling from areas of sand surplus probably represents the most attractive alternative to groins in terms of preventing starvation of down- drift beaches. In fact, beach nourish- ment may cause some short term impacts which can constitute a problem if done during periods of recreational uses of the beach area. Regional Considerations No information was found that was unique to groins in the north Pacific (Coastal Region 1). Groins are common in those por- tions of southern California (Coastal Region 2) where beaches exist. Though permeable groins with removable panels are sometimes used (Riese 1971), beach nourishment is usually required (Carlisle 1977). Southern California had a large volume of littoral drift (Berg and Watts 1971), but it has decreased in recent years due to reduced volumes of sand reaching the sea from the uplands and from loss of sand into offshore subma- rine canyons (Carlisle 1977). They also provide a habitat for rocky shore or- ganisms (U.S. Army Engineer District, Los Angeles 1974d). Groins are frequently used as al- ternatives to seawalls and bulkheads for shore protection in the Gulf of Mexico, south Florida, and the south Atlantic (Coastal Regions 3, 4 and 5). They are rare~\y completely successful unless they are planned as part of an area-wide com- prehensive shore protection program (Florida Department of Natural Resources 1973). They should be constructed only where the angle of incidence of waves with the shore is small (Herbich and Schiller 1976). The height should be kept low, no more than 1 ft (0.3 m) above normal high water. They should terminate at the 3 ft (0.9 m) depth and the length should be no more than 100 ft (30.5 m) (Collier 1975). Construction materials on the Florida coastline vary, but preformed concrete is probably more commonly used than stone due to the lat- ter 's scarcity in much of the State. Groins generally have little effect on the biota compared to other larger structures, such as jetties and break- waters (Gifford 1977). Sand-filled nylon bags were used in an experimental groin field in North Carolina (Machemehl and Bumgarner 1974). They were easily damaged and shortlived, but inexpensive compared to other con- struction materials. They were also re- latively easy to place. Groins are common in the middle Atlantic (Coastal Region 6). One study reported 45 such structures in only 8,400 ft (2,560 m) of shoreline in Ches- apeake Bay (Schultz and Ashby 1967). Rock construction worked most satisfac- torily and required the least mainte- nance in this area. Well-ring construc- tion was tried, but proved unsatisfac- tory since some of the rings washed away and maintenance requirements v/ere high (Schultz and Ashby 1967). Circulation patterns in Chesapeake Bay areas were altered by groin placement. This affect- ed erosion patterns, as well as nutrient and sediment accumulation rates in marshes (Carstea et al. 1975a). When benthic invertebrate loss and gain due to construction of groins were compared, it was estimated that the net effect was neither beneficial nor detrimental (U.S. Army Engineer District, New York 1976). The same document reports that fish will be attracted to groin areas. Groins are common shore protection 43 structures in the north Atlantic (Coast- al Region 7), particularly along the New Jersey and Long Island coastlines. No information unique to groins in this coastal region was found. Groins are used throughout the Great Lakes (Coastal Region 8) to pro- tect both shallow and steep, eroding shorelines. The Michigan Demonstration Erosion Control Program involves an on- going study of the effectiveness of a number of shore protection devices, in- cluding groins (Brater et al. 1974, 1975, Marks and Clinton 1974). Several dif- ferent designs and materials are being investigated. Some of the designs have proved successful at retarding erosion while others have failed. A great deal has been learned concerning erosion on Great Lakes shorelines. Filters are nec- essary to prevent undermining or settl- ing on clay and sand substrates (Marks and Clinton 1974). Impermeable groins are preferable for use in the Great Lakes (Lee 1961). Basic design criteria generally differ little from that of the groins in the ocean. One difference is that Brater (1954) recommends that they terminate short of the 6 ft (1.8 m) depth contour for maximum effective- ness. BULKHEADS Definition A bulkhead is a structure or parti- tion built to prevent sliding of the land behind it. It is normally vertical, but may consist of a series of vertical sec- tions stepped back from the water and built parallel or nearly parallel to the shoreline. There is no precise distinc- tion between bulkheads and seawalls, although some authors suggest the pri- mary purpose of a bulkhead is to pre- vent sliding of the land while the pri- mary purpose of a seawall is to protect the upland area from wave attack (U.S. Artry Corps of Engineers 1973b). Thus, a seawall might project above the eleva- tion of the upland area, while a bulk- head would terminate at or below that elevation. Since bulkheads, seawalls, and re- vetments are all generally parallel to the shoreline and separate land from water areas, there is some confusion of identification and the same structure may have different names in different areas. Structure Functions Bulkheads are built to prevent sliding of the land behind the struc- ture. In this capacity they serve a number of diverse functions, such as protection of uplands from erosion, creation of shorefront real estate, moorage of vessels, and other aesthetic or recreational uses. However, the uti- lity of bulkheads is that they allow protection against waves and currents without loss of land. Thus, one major function of the structure is to deline- ate between land and water with no loss of land area. In many areas bulkheads are built along shorelines and then backfilled to create or reclaim water- front land. Bulkheads are often used where land is particularly valuable or where there is insufficient land avail- able to provide a sloped surface or beach for protection. Bulkheads provide a vertical separ- ation of land and water which allows mooring of vessels adjacent to land without the necessity of a pier. A bulkhead, either alone or in conjunction with a wharf, is often used for cargo handling facilities in ports. Site Characteristics and "Environmental Conditions Bulkheads are built parallel to and on the shoreline. The location of a bulkhead on the shoreline is generally in the vicinity of the mean high water- line, but placement can range from above mean high water to below mean low water depending upon the structure's function. For example, when bulkheads are built for boat mooring, the structure general- ly is placed below the mean high water- line and the bottom, in front of the structure, is dredged to allow access at low tides. Bulkheads thus are found in all tidal zones ranging from subtidal to terrestrial. They are generally install- ed in areas of relatively low wave ener- gy because waves will usually cause scour and subsequent structural degrada- tion. 44 Bulkheads and seawalls, generally built to separate land from water areas, can serve a number of diverse functions (see Structure Functions section). They are found in many types of coastal hab- itats including areas with eroding shore- lines, narrow fringe marshes, salt and freshwater marshes, and other areas with eroding mud, silt, sand, or shin- gle beaches. Because bulkheads and seawalls are expensive to build, they typically are found in the developed areas where shorefront real estate is valuable. Placement Constraints Engineering. A number of factors must be considered in bulkhead design and construction. Important considera- tions include height and location on beach, toe protection, shape of the structure, pile penetration, structural anchorage, alignment with adjacent bulkheads, and erosion of supporting beach materials from behind the struc- ture. Many authors recommend that bulk- heads be constructed above the mean high waterline for both engineering and biological reasons (see Biological Con- straints section). Bulkhead height and placement on the shoreline should be such that waves do not overtop the structure and erode away supporting beach material, or saturate the soil and cause structural failure due to the buildup of hydrostatic pressures. When bulkheads are located on the shoreline so that they are regularly exposed to wave action, the equilibrium of the shore profile is disrupted. The foreshore typ- ically steepens and higher waves reach the structure causing increased toe scour and structural damage from un- dermining (Earattupuzha and Raman 1972). Toe protection can help prevent scour at the toe of a bulkhead and also protect the structure against changing beach profiles. Wave energy is deflect- ed as waves break against bulkheads (Figure 21). Wave energy which is not dissipated by the structure can cause scouring of material at the toe of the bulkhead. Important factors in deter- mining toe scour include wave height and steepness, beach slope, roughness and slope of the bulkhead, and beach sand size (Chestnutt and Schiller 1971, McCartney 1976). In general, structures which are not vertical and have rougher faces, such as revetments or stepped concrete seawalls, tend to reflect less wave energy seaward and are less affect- ed by toe scour (Coen-Cagli 1932, Pallet and Dobbie 1969, Sanko 1975). Adequate pile penetration is anoth- er means of preventing undermining of bulkheads from toe scour. It also pre- vents the toe of the structure from sliding seaward (Collier 1975). Sheet piling must be driven to a depth to withstand the outward pressure from ma- terials behind the structure (Ayers and Stokes 1976). Generally pilings are driven to a depth such that at least two-thirds of the piles are below ground (Michigan Sea Grant Advisory Program un- dated). Bulkheads should be securely an- chored at their ends and along their length. Adequate tiebacks along the length of the structure prevent seaward tilting (Collier 1975) (Figure 22). Tie- back rods should be coated or wrapped to prevent corrosion. Both ends of a bulk- head should be secured to prevent struc- tural failure due to erosion of materi- als from behind the bulkhead and from the shore adjoining the structure. Wing or cut-off walls are two methods of pre- venting such erosion and of tying the structure to the shore (Collier 1975, Michioan Sea Grant Advisory Program un- dated). In areas where bulkheads are adjacent to each other additional an- chorage comes from alignment of the structures. Irregular alignment of bulk- heads can cause "side erosion and cavi- tation by reflected corner waves" (Bauer 1975). Supporting materials behind bulk- heads may be washed away by leaching of sand through cracks, weep holes, and joints in the structure. Addition of a filter cloth to the structure's design will prevent such erosion and allow wa- ter drainage(Barrett 1966, Collier 1975, Dunham and Barrett 1974). In areas where the soil has a high silt or clay con- tent, the addition of a 6-inch (15-cm) sand pad between the filter cloth and 45 Figure 21. Waves breaking against the concrete bulkhead bordering the causeway in Apalachicola Bay, Florida. Photograph by E. L. Mulvihill. 46 47 the soil embankment will help prevent loss of silt and clogging of the filter (Dunham and Barrett 1974). structures 1975). (Bellis et al. 1975, Sanko Socioeconomic Bulkheads can se- recreational activities on Several au- verely limit shorelines (B rater 1954) thors urge consideration of the effect a bulkhead will have on access to public beaches pn'or to construction (Coastal Plains Center for Marine Development Service 1973, McAllister 1577, Snow 1973). Bulkheads can affect swimming, water skiing, diving, fishing, and shellfishing (Carstea et al. 1975a; Center for the Environment and Man, Inc. 1971). Borrow areas, which are some- times created to provide backfill mate- rial,may pose a hazard to unsuspecting waders, swimmers, and fishermen. The appearance of a bulkhead, both alone and as part of the overall shore- line, is an important consideration. Snow (1973) advocates designing bulkheads to blend in with the surrounding shore- line. The South Carolina Marine Re- sources Division (1974) encourages ap- plications for bulkheads that will aes- thetically and/or ecologically enhance the marine environment in areas that have been extensively developed. This agency also discourages bulkheads which have sharp angle turns because trash may accumulate there. Construction and maintenance costs are an important determinant of the type of structure built at a given loca- tion. Bulkheads and seawalls are gener- ally very expensive to construct and maintain. Initial construction and main- tenance costs for the design life of the project vary, depending upon site con- ditions, geographic region, materials used, and massiveness and design of the structure. Initial construction costs can range from $30.00 to over $500.00 per linear foot of protection for more massive seawalls. Local availability of the suitable construction materials influ- ences cost of the structures. The cost of maintenance depends upon labor ex- penses, material costs, and frequency of repair. In general, poured concrete structures are the most expensive to build, with stepped designs more expen- sive than either the vertical or sloped Biological . When planning bulkhead construction, the effects of the struc- ture on the total environment should be considered (Committee on Government Op- erations 1970). Numerous biological con- siderations were found in the literature which apply to most coastal regions: Bulkheads should be designed so that reflected wave energy does not destroy stable marine bottoms (Florida Department of Natural Resources 1973, South Caroline Marine Resource Divi- sion 1974). Bulkhead construction should avoid sharp angle turns be cause this may create flushing or shoaling problems (Bauer 1975, South Carolina Marine Resources Division 1974). Bulkheads should be designed to minimize damage to fish and shellfish habitats (Snow 1973). Vertically designed bulkheads, especially when they protrude out to minus tide levels in bays and estuaries, eliminate protec- tive habitat for salmon fry (Stockley 1974). Stair-step de- sign bulkheads or riprap revet- ments on a 45 or less degree angle provide protective habitat for salmon fry (Heiser and Finn 1970). Toes of bulkheads should not intrude into fish s paw nine beaches (Millikan et al. 1974). Fill material should not be ex- cavated from shallow water and productive wetlands (Carstea et al. 1976). When possible, existing shore- line vegetation should remain undisturbed and/or enhanced for use in shoreline stabiliza- tion (Florida Game and Fresh- water Fish Commission 1975). 48 o Marsh and mangrove edges should not be bulkheaded because this eliminates productive fish and wild- life habitat (Carstea et al. 1976, Silberhorn et al. 1974). o Bulkheads should be set landward of the mean high waterline because this allows a buffer strip of shore- line vegetation to remain (Carroll undated, Clark 1974). o Amounts of suspended sediments should be restricted during con- struction (Carstea et al. 1975a). o Bulkheads which would adversely affect littoral drift and sand depo- sition on barrier and sand islands and sand beaches are not accept- able (U.S. Department of the Inte- rior, Fish and Wildlife Service 1975b). Vertical wooden, steel, and con- crete bulkheads provide poor habitats for marine organisms (Gantt 1975). The other biological considerations may be found in the Summary of Physical and Biological Impacts section. Construction Materials There are two structural classes of bulkheads. Massive freestanding gravity structures, sometimes called seawalls, make up the first class (Figure 23). Seawalls have two functional compo- nents, the stem and the base. The stem of the structure may be curved, verti- cal, or inclined and is designed to with- stand the full force of oncoming waves. The stem generally is constructed of rubble or concrete. The base often in- cludes foundation piles which support the structure and prevent settling, and sheet pile cut-off walls which help to prevent loss of foundation material (Col- lier 1975, U.S. Army Corps of Engineers 1973b). The second class of bulkheads is constructed either of concrete slabs or sheet piles that are driven into the ground and anchored by tie rods. Con- struction materials include steel, con- crete, timber, or combinations of these materials. Pipes, cables, tires, wire netting, and baled hay have also been used as construction materials in tem- porary bulkhead structures to promote the establishment of shoreline vegeta- tion (Webb and Dodd 1976). Other mate- rials such as plywood, sheet metal, and fiberglass panels have limited useful- ness (Bellis et al. 1975). Steel sheet piling is a commonly used bulkhead construction material in the Great Lakes. About 70% of all bulk- head projects in the Chicago Corps of Engineers District use steel sheet pil- ing (Boberschmidt et al. 1976). Steel sheet piling, when used to construct bulkheads, should be interlocked, driven into the ground, and tied back for sta- bility. Steel corrodes in warm moist marine climates and should be protected with plastic, bitumin, concrete, or other suitable materials or should be made of a chemical composition resistant to marine environments (Collier 1975). Cellular steel sheet pile bulkheads are often used in place of sheet pile bulk- heads when the ground substrate cannot be penetrated due to rocks near the sur- face (U.S. Army Corps of Enqineers 1973b). Concrete bulkheads are commonly used in Florida and other more tropical climates due to their durability in com- parison to steel or timber structures (Gantt 1975). Concrete bulkheads may be vertical, sloped, concave, convex, or stair-stepped. They are, generally, either cast in place or constructed of concrete slabs with a cast-in-place con- crete cap (Figure 24). Wood is the most popular type of construction material (Figures 25 and 26). The timber should be treated with a wood preservative in warmer areas where decay and rot, insects, or marine borers pose a problem (Collier 1975). The components of timber sheet pile bulkheads usually include piles, walers, sheet piles, tie rods, and deadmen or anchor piles (Figure 27). Piles are driven or jetted into the beach, and walers are bolted horizontally to the landward side of the piles. Tie rods are also secured to the piles and at- tached to anchor piles or deadmen behind the structure. Timber sheet piling is bolted or nailed to the walers. Piles and walers are generally made of heavy 49 Figure 23. Concrete seawall in Florida. Note signs of wave damage to the base of the structure, Photograph courtesy of Florida Department of Natural Resources. Figure 24. Concrete bulkhead on Fidalgo Island, Washington. Photograph by T. Terich. 50 Figure 25. Bulkhead constructed of a series of wood piles. Photograph by C. A. Francisco. Figure 26 . Wooden sheet pile bulkhead along the Gulf coast of Florida. Photograph by E. L. Mulvihill . 51 ■o S- T3 Ol "O T3 C 03 to c o to c (L> -o r0 QJ _E .5^ ^— =3 -O 01 1 — •1 — CL +J 0J QJ .£ 1/) , ro U ■r" CL >1 +J rd to C *4- o o •1— +J 3 •^ Ol ■a •i— c > o o QJ -o Q) •i— 4J oo •<— to • s_ r- ro (XI f— 3 Ol u s- ■r" 3 +-> en S- • r— rd Ll_ CL timber. Tie rods (sometimes referred to as tie backs) when made of steel cable should be coated or wrapped to prevent corrosion (Collier 1975). Tie rods function to prevent seaward tip- ping of the bulkhead and must be se- curely anchored. Anchors typically are deadmen (horizontally placed timbers), anchor piles, or concrete anchor blocks. Construction materials used for toe protection and filters are similar to those used for revetments. Expected Life Span The expected life span of bulk- heads ranges from 10 yr to approximate- ly 30 yr. Life span is site specific and will depend upon location of the struc- ture on the beach, design wave height and period, construction materials, and climatic conditions. Timber and steel sheet pile bulk- heads have shorter life spans in warmer climates. Deterioration of wooden struc- tures from decay, insects, and marine borers is accelerated, as is the corro- sion of steel structures. Collier (1975) related one instance in Florida where a temporary wood work trestle, built from 450 untreated pine piles, was rendered unsafe for work after only 3 mo of ser- vice due to shipworms. The life span of steel structures may be less than 10 yr in warm marine environments if the steel is not coated or of a resistant chemical composition (Collier 1975). Very little data are available to assess the actual durability of various bulkhead types. However, several au- thors have pointed out that bulkheads do not provide a long-term permanent solution to shoreline erosion because the beach will continue to recede (Coastal Plains Center for Marine Development Service 1973, U.S. Army Corps of Eng- ineers 1964, 1971b). This recession may even be accelerated as a result of wave reflection from the bulkhead(Figure 28). Summary of Physical and Biological Impacts Construction effects. Construction of sheet pile bulkheads involves trans- porting materials to the site, driving or jetting piles and sheet piles, placing and securing tie rods and anchors, and backfilling behind the bulkhead. These activities require a truck for material transport, a bulldozer, a pile driver or pile jetting equipment, a crane for lift- ing heavy piles, anchors, and walers, and dredging equipment if fill material is obtained by dredging. Other types of bulkheads require similar equipment. This heavy equipment causes noise and air pollution at the site. Carstea et al. (1975a) maintain that air pollu- tion, resulting from construction of a 150 ft (45 m) timber bulkhead, should be well below Federal air quality standards and that noise will have an effect on areas within about 200 ft (61 m) from the site. However, construction noise may be sufficient to disrupt waterfowl which may be nesting or resting at or near the site. Fish and wildlife habitat is dis- rupted and/or lost due to construction activities. Damage to fish and wildlife resources depends upon the type of hab- itat in the area prior to construction, where the structure is placed on the shoreline, its size, and construction methods. The bulkhead and associated backfilling bury established terrestrial and intertidal flora and fauna. The heavy equipment used during construction disturbs vegetation behind the structure (Knutson 1977). In areas where bul knead- ing and backfilling are used to create shorefront real estate, bulkhead con- struction impacts represent the first step in a chain of events which lead to larger losses due to land development behind the bulkhead. Benthic habitat, in addition to terrestrial and inter- tidal habitat, is also lost if dredging is used to obtain fill material or to create a channel up to the bulkhead. Construction activities will cause local erosion and new sediment deposits in the vicinity of the bulkhead due to disturbance of bottom sediments during dredging, pile driving or jetting, and backfilling. New sediment deposits are often silty and can destroy spawning areas, smother benthic organisms, and reduce bottom habitat diversity and food supply (Carstea et al. 1975b). 53 Figure 28. Old bulkhead line on a beach that has continued to erode in Skunk Bay, Washington. Photograph by C. A. Francisco. 54 Several authors have pointed out that disturbance of substrate and ero- sion during bulkhead construction leads to turbidity and water quality degrada- tion (Boberschmidt et al. 1976, Carstea et al. 1975a, 1976, Environmental Qual- ity Laboratory, Inc. 1977, Gantt 1975, U.S. Army Engineer District, Baltimore 1975, Virginia Institute of Marine Science 1976). However, biological impacts from turbidity and changes in water quality have not been well documented. Con- struction activities which cause the greatest increases in turbidity are dredging and filling, and pile driving or jetting. Resuspension of bottom sed- iments from these and other construc- tion activities may release trapped nu- trients, heavy metals, and other toxic substances into the water. Suspended sediments reduce light penetration which may lead to a temporary decrease in primary productivity. Suspended materials also may interfere with respi- ratory and feeding mechanisms of the fishes, zooplankton, and benthic organ- isms. Chronic effects. Bulkheading has often been described as a relatively im- permanent means of separating land from water, especially in areas where the shoreline is eroding (Coastal Plains Center for Marine Development Service 1973, U.S. Army Corps of Engineers 1964, 1971b, Warnke 1973). Bulkheads, like revetments, protect upland areas directly behind the structure from the eroding action of waves and currents. However, they do not protect adjacent beaches or the foreshore. A bulkhead often promotes erosion of the foreshore (Bauer 1975, Bruun and Manohar 1963, Coastal Plains Center for Marine Development Service 1973, King 1972, Massachusetts Coastal Zone Management Proqram undated a, Pallet and "Dobbie 1969, Schultz and Ashby 1967, Slaughter 1967, U.S. Army Corps of Engineers undated). Erosion of the foreshore is caused by an increase in wave energy due to waves reflecting off the face of the structure (Figure 21). Foreshore erosion is particularly severe during storms. Damage inland from hurricanes and storms often is in- creased due to replacement of energy absorbing tidal marshes with impermeable bulkheads (Gosselink et al. 1973, King 1972). A bulkhead restricts movement of sand to and from beach and dune areas (Georgia Department of Natural Resources 1975, Gifford 1977). This, coupled with ongoing reflected wave energy from bulk- heads, inhibits the recovery of sedi- ments to storm eroded beaches. Bulkheads may also promote erosion of adjacent beaches (Bel lis et al. 1975, Carstea et al. 1975a, Gantt 1975, Georgia Department of Natural Resources 1975, Herbich and Schiller 1976, Pallet and Dobbie 1969, U.S. Army Engineer District, Baltimore 1975). Erosion of adjacent beaches may be accelerated until a new geohydraulic equilibrium is reached. This erosion may result from alterations in water circulation patterns or from the structure intruding into the litto- ral zone and obstructing littoral drift (Bauer 1975, Carstea et al. 1975a, Gantt 1975, Georgia Department of Natural Resources 1975). Bulkheads, like revetments, can af- fect the plant and animal communities in the upper foreshore and backshore zones. Bulkheads, constructed in wetland areas, can cause extensive damage to fish and wildlife habitat. Construction and asso- ciated backfilling destroy wetlands by covering up narrow fringe marshes, by covering up the waterfront edge, and by altering water circulation in larger shorefront marshes. Wetlands are highly productive areas which filter upland runoff and function as nutrient and sed- iment traps. Destruction of shorefront wetlands eliminates waterfowl feeding, nesting, and resting habitats and de- stroys the habitat for other birds, rep- tiles, and small mammals (Boberschmidt et al. 1976, Carstea et al. 1975a, Herbich and Schiller 1976). The construction of a bulkhead eliminates much of the intertidal zone. If the structure is built below the mean high waterline, it eliminates the tran- sition zone between the intertidal and adjacent subtidal areas. This region is the most productive zone in estuaries (Lindall 1973, Odum 1970, Stockley 1974). This transitional zone, replaced with a vertical bulkhead, provides lit- tle productive habitat. At most a wooden 55 bulkhead provides a new habitat for a few sessile and marine boring organ- isms, such as barnacles, hydroids, gribbles, and shipworms. The newly created deep water zone in front of a bulkhead often has a lower concentration of detritus, lower phyto- plankton production, and fewer benthic organisms than adjacent unbulkheaded areas (Massachusetts Coastal Zone Man- agement Program undated b, Odum 1970). The turbulence and scouring action in front of bulkheads from re- flected wave energy often prohibits vegetation from reestablishing (Gantt 1975, Knutson 1977) and may destroy existing grass flats (Gifford 1977). Ellifrit et al. (1972) studied clam populations in bulkheaded and adjacent natural areas in Hood Canal, Washing- ton. Twice as many clams were found on natural beaches at three out of the four sites studied. At two sites signif- icantly more Japanese littleneck clams, Venerupis japonica, were found in up- per intertidal regions. Differences in size and distribution were noted. Clams in the lower intertidal regions appeared unaffected by bulkheads. The authors concluded that these differences pro- bably were due to changes in current patterns associated with bulkheads. Bulkheads appeared to produce less fa- vorable conditions for settling and sur- vival of clam larvae and may have caus- ed reduction in availability of nutrients and food. Moore and Trent (1971) studied settling, growth, and mortality of oysters in two areas in West Bay, Texas. The first area was a dead end canal that had been created by dredging, bulk- heading, and filling of a coastal marsh. The second area was a dead end bayou in an unaltered part of the same marsh. The settling of oysters was 14 times greater in the natural marsh than in the canal area. Faster growth rates and lower annual mortality rates charac- terized oysters in the natural marsh. The authors attributed these differences to the poor water circulation, plankton blooms, low levels of dissolved oxygen, and high nutrient levels in the canals. Studies of shrimp in bulkheaded and natural estuarine habitats have shown natural areas to be more produc- tive (Mock 1966, Trent et al. 1976). These differences have been attributed to low abundance of organic detritus and benthic macroinvertebrates, deeper wa- ter, and loss of intertidal vegetation in bulkheaded areas. Bulkheads also can affect fish spawning, feeding, and nursery habitat. For example, bulkheads have been shown to alter salmon fry behavior in Puget Sound, Washington (Heiser and Finn 1970, Stockley 1974). Vertical bulkheads cause an abrupt habitat change with few shal- low water areas. Salmon fry tend either to go out into deeper water when con- fronted with a bulkhead or to concen- trate near bulkheads and not go around them. Both circumstances make salmon fry extremely vulnerable to predation. Stair-step design bulkheads or riprap revetments on a 45 or less degree angle were found to provide protective habitat for salmon fry (Heiser and Finn 1970). In another study, (Millikan et al. 1974) bulkheads extending down below the mean high waterline were found to bury and destroy smelt spawning substrate in Puget Sound and Hood Canal, Washington. As a result of this study, State bulk- head criteria for surf smelt spawning beaches were modified to protect upper intertidal and sand-fine gravel beach areas. Cumulative effects. Physical and biological impacts from the construction of a number of bulkheads in a coastal area may have a cumulative effect, how- ever, no pertinent studies were found. Irregular alignment and patchy bulkhead- ing along a shoreline often create ero- sion pockets between bulkheads on natu- ral beaches (Bauer 1975). Extensive bulkheading of wetlands on the shores of estuaries and bays can severely reduce fish and wildlife habitat and impact es- tuarine related fisheries of a whole re- gion, as well as waterfowl populations. For example, Lindall (1973) identified bulkheading of south Florida's estuarine shorelines and the resulting destruction of the nursery grounds as a threat to the estuarine-dependent fisheries (about 85% of the area's commercial fisheries) of that region. Clearly, examination of the physical and biological impacts of 56 bulkhead construction on a case-by-case basis ignores a host of potential cumula- tive physical, chemical, and biological impacts (Fetterolf 1976). Structural and Nonstructural Alterna- tives The design of bulkheads can be al- tered, or they can be used in conjunc- tion with other structures, to modify their impact. Bulkheads can be stepped back in a series of low vertical walls which will provide some variation in depths in front of the structure. When enough steps are provided, the struc- ture becomes a revetment. (There is no exact definition which differentiates a stepped bulkhead from a revetment.) Another alternative is to use a bulkhead landward of mean high water to protect uplands from higher wave conditions and use a sloping revetment or vegeta- tion to protect the foreshore or inter- tidal area. The alternatives must correspond to the intended function of the struc- ture. If the function of the bulkhead is to protect the backshore land area and prevent sliding, an alternative structural solution is to build a revet- ment. Offshore breakwaters can also be used to reduce the wave attack on the land. Buildinq up the beach (to protect the uplands) by groins or beach nourishment is also an alternative to bulkheads. Another alternative is to let the land erode and move or abandon upland structures. (See also Revet- ments. ) If the bulkheading is needed to achieve a vertical interface between wa- ter and land, then alternatives must re- spond to the need for the vertical in- terface. If the vertical face is for moor- ing vessels, the same function can be achieved by building a pier at right angles to the shore or placing mooring buoys offshore. If the vertical interface is needed for recreational or aesthetic purposes (to allow people to get close to the water), a pier or structure pro- jecting into the water presents a logical alternative. The predominant criticism of bulk- heads relates to their vertical design 57 and the consequent loss of variable depths and intertidal zones which exist on natural shorelines. The alternatives which best protect these features are either beach nourishment to maintain a natural-like shoreline or revetments. A revetment will provide protection to a specific site and, if designed properly, will allow variable depths and inter- tidal zones to be retained. Regional Considerations Along the north Pacific coastline (Coastal Region 1), bulkheading is most frequently encountered in Puget Sound. Bulkheads have been shown to alter sal- mon fry behavior in Puget Sound, Wash- ington, and in the Columbia River estu- ary (Heiser and Finn 1970, Stockley 1974). Vertical bulkheads often elimi- nate shallow water regions, and salmon fry behavior in the vicinity of such structures makes them extremely vulner- able to predation. Stair-step design bulkheads or riprap revetments on a 45 or less degree angle were found to pro- vide protective habitat for the salmon fry (Heiser and Finn 1970). Another con- cern in Puget Sound and vicinity is the destruction of surf smelt spawning hab- itat by bulkheading spawning beaches. State bulkhead criteria for surf smelt spawning beaches were recently modified to protect upper intertidal sand-fine gravel beach habitat (Millikan et al. 1974). Bulkheads built at the bottom of sea cliffs are one attempt to control cliff erosion in southern California (Coastal Region 2). They frequently are found in conjunction with small boat harbors in this region. Areas of the Gulf of Mexico (Coastal Regions 3 and 4) have been extensively bulkheaded. In Mississippi, from Biloxi Bay westward, including the eastern half of Hancock County, the entire shoreline has been altered by bulkheading and artificial beach nourishment (Virginia Institute of Marine Science 1976). Bulkheads are also prevalent along the Atlantic coast (Coastal Regions 6 and 7). They are found almost continuously along northern New Jersey shorelines (Yasso and Hartman 1975). A common practice in Galveston Bay, Texas, and in southern Florida (Coastal Regions 3, 4, and 5) has been to build bulkheads along vegetated shorelines and then to backfill the area to create wat::front real estate (Lindall 1973). The natural shoreline is usually altered by channelization, bulk heading, and fill- ing. Houses are built on narrow strips of land which are separated by a series of dead-end channels (hence the name "finger-type" development). The biolog- ical effects of this type of development in bays and estuaries have not been well researched. However, several stud- ies do give some indications of potential impacts. Physical changes in estuaries and bays include: reduction in acreage of shore and marsh vegetation, changes in marsh water circulation patterns and nutrient input into the bay or estuary, changes in water depth and substrates, and the conversion of aquatic areas to upland areas with a resulting decrease in water area in the bay or estuary (Corliss and Trent 1971, Cronin et al. 1971). The ecology of one finger-type housing development in West Bay, Texas, has been studied extensively. Phytoplankton production (Corliss and Trent 1971, Trent et al. 1976), sub- strates, and hydrology (Trent et al. 1976)were studied in an open bay area, in a bulkheaded canal area in the de- velopment, and in an adjacent natural marsh area. In general, productivity was higher in the marsh than in canal areas and lowest in the open bay. The plankton blooms followed by low levels of dissolved oxygen, high nutrient lev- els, fish kills, and lowered production of oysters, benthic macroin vertebrates, and shrimp in summer months indicated the presence of eutrophic conditions in the canal areas of the housing develop- ment. Similar eutrophic conditions have been reported in housing developments in Florida (Lindall 1973, Taylor and Saloman 1968). Trent et al. (1972) noted that standing crops of benthos, fish, and crustaceans were relatively high in the canal areas in spite of ap- parent eutrophic conditions. The au- thors were unsure if this was due to canal areas in the housing development being self-supporting in terms of vege- tative production or whether productiv- ity relied upon the detritus carried in from the adjacent marsh by tidal action. REVETMENTS Definition A revetment is a sloped structure built to protect existing land or newly created embankments against erosion by wave action, currents, or weather. Re- vetments are usually placed parallel to the natural shoreline. Riprap (randomly placed stones) and gabions (a wicker- like basket which can be filled with stones) can be included in this defini- tion. Structure Functions The primary function of most revet- ments is to protect the area landward of the revetment from erosion or scour due to waves or currents. This protection is due to the armoring characteristics of the revetment and its ability to dis- sipate wave energy. Revetments are nor- mally used where it is necessary to re- tain the shore in a more seaward posi- tion relative to adjacent lands, where there is little or no protective beach in front of the land to be protected, or where it is desired to maintain a cer- tain depth of water in front of a struc- ture. Revetments are especially useful at the mouths of waterways where erosion is frequently severe (Coastal Environ- ments, Inc. 1976). They may also prevent undermining from wave erosion when plac- ed along the seaward slope of eroding dunes or cliffs (Yasso and Hartman 1975). Revetments are often used to pro- tect the foundations of structures, such as bulkheads or buildings (Figure 29), from erosion. Figures 30 and 31 give examples of riprap and concrete revet- ments. Revetments are generally used where there is the potential for high wave energy. Bulkheads can function in a similar capacity, but offer far less energy dissipation. Site Characteristics Revetments are generally built to protect eroding shorelines. They are found in many types of coastal habitats including areas with eroding embankments or cliffs and little or no protective beach. Their most common occurrence is in developed areas where the shorefront property is endangered by erosion. 58 Figure 29. This riprap revetment functions to limit erosion of the parking lot at the Kingston, Washington* ferry terminal. Picture was taken at low tide. Light and dark colored bands on the revetment are due to biological zonation. Photograph by C. A. Francisco. 59 Is 1 +-> Ol s= s- -i- o • o *•- "o Q- C CU 3 +-> -c o 00 C C -4-" O t- •r- o> 4-> "O 3 S- 1/0 3 4- -M O +-> <_> -C •.- -C oiau •r- 3 _J co E ai T3 C C 5- O •!- (O 3 aj cu C3 -C .— +-> -O +J « CO l/l O (O .c o O (O • 3 S- oo co a. E rs «n- co (1) Oil/) -C O -l-> +J l— C CU (fl DIE ■*-)£=+-> O -r- CU CU +■> > +-> 4- O) O -r- S- S_ S- Q.-0 C • O O +-> CD T- u C CD.O co CU i- n3 • r— E o +J _J c CU M- o s_ CU • Ll_ (■ c m O to • Q-+-> 3 , ro CU _Q 3 -^ (O _£Z O » E CL ro +-> ro c • &- CU •(- T3 cn s- o c o 3 Q. 3 +-> CT) O o ■r- O S- -C Ll_ z CT1Q. 60 Figure 31. Concrete revetment along U.S. Highway 98 in the vicinity of Port St. Joe, Florida. Note the toe protection at the base of the revetment. Photograph by E. L. Mulvihill 61 Conventional revetments typically provide protection from well above the mean high water line to well below the mean low water line. Conventional re- vetments thus extend from the terres- trial zone to the subtidal zone. Upper beach revetments extend from above the mean high water line to an area between the mean high water line and the mean low water line. This type of revetment generally lies within the region extend- ing from middle intertidal zone to the terrestrial zone. Revetments can also be used entirely above the mean high water line for protection against storm generated tides. Revetments are usual- ly constructed parallel to the natural shoreline. Placement Constraints Engineering. Several factors should be considered when evaluating the de- sign of a revetment. Design considera- tions include design life of structure, design wave, seasonal changes in beach profile, water level range (e. g. .changes due to tides, storms, and for the Great Lakes seasonal lake level), beach compo- sition,and beach use (McCartney 1976). Once these site conditions are known, alternate types of revetments may be evaluated. Armor facing requirements, wave runup heights, toe scour depth, toe protection needs, revetment slope, revetment length, and filter require- ments vary with different types of re- vetments. Revetment slope length and place- ment on the shoreline should be such that waves do not overtop the structure and erode away the supporting beach or saturate the soil and cause structural failure due to the hydraulic processes. Wave runup, an important factor in the determination of revetment slope length, depends upon water depth at the toe of the structure, slope of the beach in front of the structure, and the slope, shape, roughness, and porosity of the revetment (U.S. Army Corps of Engi- neers 1973b, McCartney 1975). Other factors which determine revetment slope length include water level range, beach slope, toe scour depth, and minimum water depth allowed at the toe of the structure (McCartney 1976). Toe protection is necessary to pre- vent scouring at the base and to protect the structure against changing beach profiles. Revetments possess very little internal stability, relying on the un- derlying beach which they protect (Fig- ure 32). Undermining of the structure at its toe can lead to failure of the entire structure. Wave energy is de- flected both landward and seaward as waves break against revetments. Wave energy which is deflected seaward can cause scouring of material at the foot of revetments (U.S. Army Corps of Engi- neers 1973b). Factors affecting the amount of toe scour include slope, per- meability and roughness of the revet- ment, water depth, hypothetical surface of wave reflection, wave height and steepness, and beach sand size (McCartney 1976, Sato et al. 1968). In general, rougher, flatter, and the more permeable revetment surfaces cause less toe scour and require less toe protection. Structural failure due to scour may be avoided by incorporating adequate toe protection into the design of revetments. Common toe protection methods are addressed in the construc- tion materials section. The supporting materials under structures may also be washed away if an adequate filter is not used. A filter prevents undermining of the revetment, distributes armor unit weight, and pro- vides for relief of hydrostatic pres- sures (Collier 1975, McCartney 1976). Ideally, a filter layer prevents scour- ing of supporting shore material and al- lows water drainage. The amount and type of filter material needed is determined by beach composition, water depth, type of armor units, and current velocities. In areas of heavy wave action, armor units are often placed on a scour pad of plastic filter material (filter cloth) and stone. Special care must be taken in design and construction of imperme- able revetments to prevent excessive landward hydrostatic pressure. Design- ing the structure with gravel or with rock weep holes are ways to help prevent this potential problem (McCartney 1976). Materials used for armor facings should be designed to remain intact 62 Figure 32. Failure of this interlocking concrete block revetment was primarily due to settling and erosion of supporting beach material. Due to its flexibility, this structure still affords some protection. Photograph courtesy of Florida Department of Natural Resources. 63 under anticipated environmental condi- tions. Armor facings constructed of materials such as riprap or rubble should have components which are dense and heavy enough not to be mov- ed by waves. Revetments with perme- able armor units (such as gabions) or interlocking armor units rely less on mass of the individual structural compo- nents to withstand wave energy than do more solid type revetments (Docks and Harbor Authority 1965). More detailed discussions of the various types of ar- mor units, their advantages and disad- vantages, are found in the Shore Pro- tection Manual (U.S. Army Corps of Engineers 1973b) and the Survey of Coastal Revetment Types (McCartney 1976). Socioeconomic. Social and economic considerations can affect the location and type of structure built at a site. Local laws, costs of structural alterna- tives, historical points of interest, cur- rent and future uses of the area, and aesthetic values are some of the criteria which influence the placement of a re- vetment. Current and future uses of an area help to determine the need for a revetment at a given location. Beach use influences the type and location of the structure on the shoreline. The design life of a temporary re- vetment to protect an exposed embank- ment during construction activities would be shorter than the design life of a revetment built to protect a shore- front dwelling from damage due to beach recession. Revetments can se- verely affect waterfront recreational activities, such as swimming, boating, and shell- fishing. McCartney (1976) points out that a beach used "for re- creation and other purposes may dictate use of upper beach revetment to contain runup and sandfill on the beach face seaward of the revetment." Several authors have commented on the visual impact revetments have on the shoreline. Structures which resem- ble and follow the natural shoreline seem to have less adverse impact on the scenic or aesthetic values of an area. For example, gabions are sometimes viewed as a more aesthetically pleasing type of revetment than either brickwork or concrete slabbing because of their resemblance to the natural stonework (Docks and Harbor Authority 1965). A rock revetment which was to be built at Sunset Cliffs, San Diego County, Cali- fornia, was viewed as more aesthetically acceptable than a more formal structure (U.S. Army Engineer District, Los Anqeles 1970). Bel lis et al. (1975) point out that "the availability of 'free' mate- rials such as demolished buildings, old tires, junked cars, and other debris all too often leads to really bizarre shore- lines..." An example of such a shore- line is found in Figure 33. Some au- thors, however, view any type of revet- ment as an artificial intrusion that is an aesthetic affront to the shore envi- ronment. Bauer (1975) made the following comment with reference to riprap revet- ments: "The most negative feature of rip- rap, however, resides in the of- fending visual impact and environ- mental degradation of the shore resource. The use of such rock heaps, Just as in the case of the streambank revetments, has now mushroomed into a serious shore despoilage - a syndrome that is lining our beautiful beach environ- ments with ugly, incompatible bor- ders and backdrops of rubble." Economic feasibility often deter- mines the number and types of structural alternatives available for a given loca- tion. Initial construction and mainte- nance costs for the design life of the project vary depending upon site condi- tions, geographic region, and materials used. Initial construction costs can range from $25.00 to $200.00 or more per linear foot of protection. While revet- ments tend to be less expensive than bulkheads, those constructed along the open coasts or to protect barrier beach- es are expensive to build and maintain relative to those built in semiprotected and protected environments. Local avail- ability of the suitable construction materials influences cost of the struc- ture. The cost of maintenance depends upon the labor expenses, material costs and frequency of repair. For example, nylon bag and polyethylene tube revet- ments are relatively inexpensive to in- stall, but may be expensive to maintain. 64 e4P "r~ ^ S&i*"4^t _• »• |^^^__ ^ ■ . • . ^^ s "f \i^ 4A UrJ? ^Ssfev ^ kt \! v ; fiW ^^ ^^ % L3 1 ^^ \V ^S Figure 33. Pictured is a junk car revetment in Florida. Due to corrosion, the life span of car body revetments generally is less than 5 years in brackish water. There are also aesthetic considerations regarding this type of revetment. Photograph courtesy of Florida Department of Natural Resources. 65 Sandbags and tubes may easily be cut open by vandals (Marks and Clinton 1974) and deteriorate quickly, thus re- quiring frequent repair. Biological. The Buffalo Army Engi- neer District (U.S. Army Engineer Dis- trict, Buffalo undated a) in issuing a general permit for shore protection in Lake Erie listed several biological con- straints on the revetment construction which may be applied to all coastal re- gions: o Armor unit revetments should be made of clean, non-pollut- ing material. Any material contaminated with grease, phenol, lead, or other toxic elements should not be used. o Revetments should not be constructed during the fish spawning periods. o Revetments should not be constructed in wetlands; in areas serving as habitat for threatened or endangered species; in important fish spawning areas; or in signi- ficant waterfowl or shorebird nesting, feeding, and resting areas. Revetments with facings that are highly irregular (such as riprap) and have a shallow slope have a greater abi- lity to support marine life (Gantt 1975). Although revetments do provide a new irregular habitat which does support greater marine life than vertical sea walls, there is an initial loss of organ- isms and habitat by placement of revet- ments. Construction Materials There are two structural classes of revetments (U.S. Army Corps of Engi- neers 1973b): rigid, cast-in-place, and flexible or articulated armor unit revet- ments. Rigid, cast-in-place types of revetments are constructed of cement, asphalt, or bitumen grouted stone. A concrete revetment is very effective against wave attack, but water must be removed from the construction area to pour the concrete. A concrete revet- ment is depicted in Figure 34. Compo- nents of armor unit revetments include an armor face, filter, and protective toe (McCartney 1976). The armor face is the outer layer of the structure which serves to dissi- pate wave energy as waves are deflected landward. Materials commonly used as armor facino are shown in Table 2 (McCartney 1975, 1976; U.S. Army Corps of Engineers 1973b). Riprap revetments are illustrated in Figures 30 and 31. A Nami ring revetment and an interlocking concrete block revetment are shown in Figures 35 and 36. A filter serves as an interface be- tween the armor facing and the native soils which the structure protects. Some commonly used filters include gravel, auarry spalls, filter cloth, and combi- nations of gravel and a filter cloth, and quarry spalls and a filter cloth. Toe protection is necessary to pre- vent scouring at the base of revetments and to protect the structure against changing beach profiles in front of the structure. Common types of revetment toe protection include aprons which will sag into any scour hole that develops, buried toes, toes weighted with extra layers of armor units (armor units are not necessarily the same as those used on the rest of the structure), flexible mats such as gabions or filter cloth filled with sand, bag or rock sills placed seaward of the toe to trap sand and bury the toe, sand or gravel stock- piles, cutoff walls, and anti-erosion rings (McCartney 1976). Expected Life Span The expected life span of revet- ments ranges from 5 to 30 yr or more. Expected life span will vary depending upon construction materials, the wave height and period the structure was de- signed to withstand, and the climatic conditions to which the structure is ex- posed. Damage to rubble-mound structures is generally progressive, and the Shore Protection Manual (U.S. Army Corps of Engineers 1973b) recommends considering both the frequency of damaging waves and 66 -o E S- +J CD CD S- +J CD -a ■o c (0 to o to c QJ to o 13 S- 4-> 00 c o LJ . +J C CD e +-> O) > CD • S- CO c 03 o *r— <^- 4J O ■r" -o CD c r— o ■1 — o M- O CD S- +-> CL. ■r— to a s_ *3- 03 ro r^ 13 CD U S- • r- 3 4-> CT> S- •f— (13 U_ CL 67 CO CD c u i- o E i_ ro c OJ E -t-> OJ > CD s- rO I CI o % CO xj V OJ a. S^ >> 3 — — ■)-> o 03 • 4- :\j 3 . £Z I E I IS 15 I "3 E ro CJ +-> « 2 -C +-> i_ £1 a; C Q. OJ OJ OJ +j Or) •r— CO >> E V CO -M E fO *» ro 0) o S- 4- 3 VI ^~ cj CJ 'i— r— * -*: n C r— ro a> o c "O l/> O +-> o »l— c CJ) u +-> i_ QJ .— _e ro ro C O S- Xj +-) CO XJ. x. 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QJ ro X i- E CJ O Q.-r- S- r- CU O •^- E ro t_ CJ CL s_ +-) QJ s_ ^ S- "U C -^ ro OJ XJ U XJ ro +J ro O X= , — S- QJ C O 3 cj co 3 CT i — c CJ 4- 1/1 • -»-> D) « i — o ro -x: o OJ *« ^ C TJ CO CJ CJ 4-> QJ o 4-> s- CO CO •^ i_ -^ CJ CO CO S_ O QJ o S- QJ -^ ro CJ i_ o> * '•!— 4. c ro co CJ CD o OJ o to e s A o XJ CO- O 1 p — +-> -^ '(— c x: on u ■i- O • i — j*: • X3 0J i_ CJ S- o c: +-> C S_ i— CJ i- o CJ S- CJ o •.- QJ ■r— ro ■1-J 4-> O 4^ OJ r— 4-1 ■f — CJ XJ r— • r— XJ > 2 -& ul 'TJ OJ +-> OJ X r^ c X3 E ro O ro c o o •1— ro CZ5 i (_) t— ( CO CJ (_J z: >1 ro ( — J_ QJ > O J^ CJ o a i^ o E 4-) Cl c ro Tj o 4-> S- 4- OJ Cl •r— C/ ■1 — c OJ ad XJ > 68 Figure 35. A Nami Ring revetment was constructed in 1974 at Little Girls Point on Lake Superior as part of the Michigan State Demonstration Erosion Control Program. Damage to this structure was extensive after two years of service. Photo- graph courtesy of the Michigan State Department of Natural Resources. Figure 36. An interlocking concrete block revetment forms a checkerboard pattern on the shoreline. Vertical structure at top of revetment is a reinforced concrete wave screen. Photo- graph courtesy of Portland Cement Association. 69 the costs for installation, protection, and maintenance when selecting the de- sign wave. On the Atlantic and Gulf coasts of the United States, hurricanes may provide the design wave criteria; whereas on the north Pacific coast, it may be provided by annually occurring severe storms (U.S. Army Corps of Engineers 1973b). It may not be econom- ically feasible, however, to design a structure which will withstand a hur- ricane which may occur once every 20 to 100 yr. Structures located in areas with frequent storms should be built to withstand the storms and to avoid high annual maintenance costs. McCartney (1975) selected the relatively short de- sign life of 5 to 10 yr for the upper beach revetments discussed in his study. This design life is economical and "compatible with erosion protection needs for high lake levels in the Great Lakes" (McCartney 1975). Gantt (1975) has described riprap revetments, if cor- rectly designed and constructed, as be- ing relatively permanent structures. However, very little quantitative data are available to assess the actual dura- bility of riprap or other revetment types. Summary of Physical and Biological Impacts Construction effects. Construction of revetments involves transporting ma- terials to the site, preparing the em- bankment to be protected, laying filter materials, placing armor units, and pro- viding toe protection. These activities involve a truck for material transport and a front-end loader for construction. This heavy equipment causes noise, vi- bration, and air pollution at the site. Carstea et al. (1975a) noted that con- struction time is relatively short for structures such as riprap revetments. They also commented that air pollution is well below Federal air quality stand- ards and that noise from construction activities will only have an effect on areas within about 100 ft (30 m) of the site. However, construction noise and activity may be sufficient to disrupt waterfowl which may be nesting or rest- ing at or near the site. Construction activities also disrupt vegetation direct- ly behind revetments (Knutson 1977). Habitat is lost due to the struc- ture being placed over the previously existing substrate (Gantt 1975). Estab- lished intertidal flora and fauna are often buried during the revetment con- struction (Coastal Plains Center for Ma- rine Development Service 1973). All plant and animal communities from behind the revetment to beyond the revetment toe are therefore affected by the con- struction of revetments. However, in many cases, such as the construction of riprap revetments, a new and different type of habitat is created. Construction activities will cause local erosion and new sediment deposits in the vicinity of the revetment (Orto- lano and Hill 1972). This will occur from disturbance of bottom sediments and erosion of exposed substrate. New sedi- ment deposits are often silty and can "destroy spawning areas, smother benthic organisms, and reduce bottom habitat di- versity and food supply" (Carstea et al. 1975). Several authors noted that distur- bance of bottom sediments and erosion results in increased turbidity and water quality decradation (Boberschmidt et al. 1976; Cars"tea et al. 1975b; U.S. Army Engineer District, Buffalo undated a; Virginia Institute of Marine Science 1976). Resuspension of bottom sediments may release trapped nutrients, heavy metals, and other toxic substances into the water column. Suspended materials can also interfere with respiratory and feeding mechanisms of aquatic organisms. The extent of impacts from construction activities has not been well documented. The type of revetment, its location on the shoreline, construction methods, and type of substrate all play a role in de- termining construction effects. For ex- ample, turbidity from construction ac- tivities is greater and lasts longer in areas with finer sediments (Carstea et al. 1975a). Even with a fine grain type of substrate, riprap revetment construc- tion should not lead to levels of the resuspended sediments which exceed those required for the protection of aquatic life (Carstea et al. 1975a). The effects of revetment construction must be evalu- ated in light of the duration of the 70 construction period and the severity of disturbance. Chronic effects. The presence of a re- vetment in an area leads to a number of physical and biological changes at the site and in the surrounding shoreline. A revetment, when adequately designed and constructed, will control erosion of the shoreline on which the structure sits; however, it will not stabilize ad- jacent beaches or the foreshore in front of the structure. Alterations in the foreshore follow- ing revetment construction are site-spe- cific and difficult to predict. Unlike the groins, revetments generally do not fa- cilitate beach accretion in either the backshore or foreshore regions and may promote beach erosion in front of the revetment (Brater 1950, Michigan Sea Grant Advisory Program undated ). Fore- shore erosion, however, will be less from a revetment than if a bulkhead or seawall had been constructed because wave energy tends to be dissipated rather than reflected as waves run up revetment faces (Pallet and Dobbie 1969). In fact, construction of revet- ments on severely eroding shorelines can actually improve water quality by reducing turbulence (Carstea et al. 1975a, U.S. Army Engineer District, Buffalo undated a). Erosion of the fore- shore can result from toe scour, increas- ed backwash during severe storms (Brater 195C), and seasonal and long- term fluctuations in the beach profile in front of the structure. G if ford (1977) has noted bottom changes in front of revetments in Florida which usually in- volve deepening near the shore and parallel offshore bar formation. Well-designed and properly placed revetments typically do not promote the beach growth as they offer very little obstruction to littoral drift. Poorly de- signed or placed revetments can cause increased erosion of adjacent beaches (Herbich and Ko 1968, Herbich and Schiller 1976). Erosion of adjacent beaches may result from alterations in water circulation patterns or from the structure intruding into the littoral zone and obstructinq littoral drift (Car- stea et al. 1975a, Gifford 1977). Construction of a revetment is a physical alteration of the shoreline which brings with it many biological changes. The structure itself buries established flora and fauna. The revet- ment facing affords a new and different type of substrate. A revetment thus pro- vides a new habitat for various terres- trial, benthic, and aquatic organisms. The plant and animal communities which colonize a revetment will have a commu- nity structure which is different from the one in existence prior to construc- tion. The diversity and abundance of or- ganisms living in and around a revetment will vary, depending upon the type of revetment facing, energy conditions, its location on the beach, and the type of substrate on which the revetment was built. In some instances, a revetment can increase species diversity and abun- dance compared to what was previously in the area. An example of such an area is Rincon Island, an offshore man-made is- land in California which is protected by rock and tetrapod revetments. Rincon Island's revetments support a diverse population of over 225 species of plants and animals while the mainland, an area one-half mile distant with sandy beach- es, has fewer than 12 species (Brisby 1977). Prior to construction, about 20 to 25 different species lived in the Rincon Island area (Keith and Skjei 1974). In general, revetment facings that are highly irregular and have a shallow slope are favored biologically over structures with smooth and/or steeply sloped surfaces. Such structures tend to dissipate wave energy better and have greater ability to support various organisms (Cantt 1975). A change in beach substrate, as a result of revetment construction, may alter the types of aquatic organisms which are able to utilize the area for growth, food, reproduction, and protec- tion. For example, fish species requir- ing rocky substrates for spawning will be favored in the riprapped areas over those requiring sand, gravel, or vege- tated substrates (U.S. Army Engineer District, Buffalo undated a). Heiser and Finn (1970), in a study of chum and pink salmon in marinas and bulkheaded 71 areas in Puget Sound, found that the spaces between rocks in riprap revetted areas provided protection for salmon fry avoiding predators. Revetments also affect the plant and animal communities in the upper foreshore and backshore zones. Revet- ments constructed in wetland areas can cause extensive damage to wildlife habi- tat. Carstea et al. (1975a) have describ- ed wetland destruction as the "most significant ecological impact of riprap construction." Revetments can damage or destroy wetlands by covering up narrow fringe marshes and altering wa- ter circulation in larger shorefront marsh areas. Wetlands are highly pro- ductive areas which filter upland runoff and function as the nutrient and sedi- ment traps. Destruction of shorefront wetlands eliminates waterfowl feeding, resting, nesting, and nursery habitats and destroys the habitat for other birds, reptiles, and small mammals (Bobersch midt et al. 1976, Carstea et al. 1976, Herbich and Schiller 1976). Cumulative effects. No studies were found that investigated cumulative phys- ical and biological impacts due to the existence of a number of revetments within a coastal area. Revetments are relatively small in size. The effects of a single revetment may be relatively in- significant in a coastal area due to the size of the structure, the size of adja- cent undisturbed areas, and even re- cruitment into the revetment-produced habitat. The physical and biological impacts from the construction of a num- ber of revetments in a coastal area may have a synergistic effect. For example, extensive riprap revetting of a sandy coastline will change what once was a sandy habitat into a rocky intertidal habitat. Examination of the physical and biological impacts of revetment con- struction on a case-by-case basis ig- nores a host of potential cumulative physical, chemical, and biological impacts (Fetterolf 1976). No information was found regarding the cumulative effects of revetments in connection with other shoreline structures. All structures in an area should be evaluated concomi- tantly. Structural and Nonstructural Alterna- tives There are numerous alternative structures and materials available for building revetments. They are described earlier in this section and more com- pletely in the Shore Protection Manual (U.S. Army Corps of Engineers 1973b) and the Survey of Coastal Revetment Types (McCartney 1976). In addition to the alternative designs and materials for revetments, either offshore breakwaters, groins, or bulkheads may constitute al- ternatives depending on the conditions at the site. A revetment generally protects the landward area from erosion or scour due to waves or currents. An offshore break- water may accomplish this same purpose by dissipating the wave energy before it strikes the eroding land area. A break- water may secondarily interrupt the longshore littoral transport of sedi- ments. This can buildup the beach which further protects the adjacent uplands. Objections to a breakwater as an alter- native to a revetment are the cost, the interruption of longshore transport and possible impact on adjoining land areas, and the visual impact. In addition, a breakwater might constitute a hazard to navigation. A groin or system of groins might indirectly accomplish the same function as a revetment by causing the accumula- tion of littoral drift which widens the beach cross section and ultimately pro- tects uplands from wave attack. The groins, might reduce wave attack depend- ing on spacing, height of the groins and angle of wave attack. The groins can cause undesirable side effects due to their tendency to interrupt longshore transport with the resultant impact on downdrift beaches. Erosion problems are, in some instances, only displaced by groins. A bulkhead or seawall could be used as an alternative to a revetment. How- ever, due to the greater expense and lack of environmental advantages, bulk- heads would normally not be selected as alternatives to revetments. The circum- stances under which bulkheads are used are described in another section of this report. There are a number of nonstructural procedures which may constitute viable 72 alternatives to the revetments depend- ing on the site specific circumstances. Beach nourishment from onshore or offshore locations can be used to widen and raise the beach profile. This, in turn, will dissipate the wave energy and may reduce erosion of the upland areas. This solution is temporary as the wave energy causing erosion will be focused on the new beach and, in time, transport the sand either offshore or alongshore, thus re-exposing the erod- ing area. Beach nourishment can also be used in conjunction with groins as an alternative to revetments. Vegetation can also be used to re- tard erosion. Vegetation is particularly suitable against wind- or rain-caused erosion. Vegetation cannot withstand constant action of waves or currents and would need to be supplemented by other structures, or means, to prevent erosion. Vegetation is often used well above the surf zone for stabilization and accretion of sand on dune areas. In areas of relatively low wave energy, the establishment of a fringe marsh might be an alternative to revetment construction. Most structures exposed to sea conditions are ultimately subject to ero- sion and failure. Th-is problem can be avoided by zoning against development of foredunes, cliffs, or other areas sub- ject to erosion by the sea. Setback reg- ulations are another means of assuring that structures will not be threatened by shoreline erosion at a future date. One problem is that it is not always possible to forecast the extent of possi- ble erosion over the life of the struc- ture. This is particularly true in cases where groins, jetties, and breakwaters are being constructed in adjacent areas which might lead to rapid accretion or erosion of the shoreline. Also, unusual storm and wave conditions can have drastic effects on a shoreline that has been reasonably stable in the previous years. Assuming an upland building or facility is threatened by an eroding shoreline, an alternative to revetting the shoreline is to move the building or facility back on the lot, leaving the forward part of the land to erode. This, of course, requires sufficient land to allow relocation of the endan- gered building and a structure which can be economically moved. This remedial action might have to be repeated in the future. Regional Considerations Riprap revetments are a common means of protecting eroding shorelines in Puget Sound (Coastal Region 1). They are also common in estuaries and harbors along the coast of Washington, Oregon, and northern California. Riprap revet- ments are used to protect railroad tracks, roadbeds, residential lots, and uplands from erosion. Heiser and Finn (1970) studied chum and pink salmon in marinas and bulkheaded areas in Puget Sound. These authors recommended using riprap revetments with irregular, 40° or less angle facings in lieu of vertical bulkheads as this type of revetment pro- vides protective habitat for young sal- mon. No information sources concerning revetments unique to Coastal Regions 2, 6, 7, or 8 were found. Physical and bio- logical impacts are similar to those previously described. Limited quantitites of hard igneous rock in peninsular Florida (Coastal Re- gions 3, 4, and 5) make riprap revet- ments expensive as rock must often be shipped in from other states. Coquina rock, mined from quarries in the St. Augustine area, has proven to be a dur- able construction material for marine structures; however, this source of sup- ply is almost exhausted. Limited sup- plies of hard native limestone are available in the Tampa area (Collier 1975). RAMPS Definition A ramp is a uniformly sloping plat- form, walkway, or driveway. The ramp commonly seen in the coastal environment is a sloping platform for launching small craft. A launching ramp will nor- mally slope continuously from above the high water line to below the low water line to allow launching of boats or air- planes under varying tidal or water 73 level conditions. A launching ramp may be surrounded by additional structures, such as pilings or piers, and may be protected by a breakwater. Structure Functions A launching ramp provides a means to set afloat and retrieve boats which are usually mounted on rubber-tired trailers. However, airplanes also use ramps. Launching ramps will usually be accompanied by parking lots for automobiles and trailers and will be con- structed in conjunction with a landing pier or other shoreline structures, such as pilings or breakwaters. A ramp has many of the same phy- sical characteristics as a revetment; however, its function is different. Re- vetments are usually installed in high energy environments, whereas ramps are installed in relatively quiescent areas. Site Characteristics and Environmental Conditions Ramps extend into the water, per- pendicular to the shorelines and slope at an angle of 122 to 15% from the ter- restrial zone to below the low intertidal zone. They are usually constructed in areas where there is fairly deep water close to shore and where there is a rea- sonable amount of protection from winds and waves. Ramps are often associated with marinas and would, therefore, be placed in similar environmental condi- tions. Placement Constraints Engineering. The design of a launching ramp may wary depending on expected usage and site characteristics. Figures 37 and 38 show examples of two different ramp designs. Ramps ranoe in width from 1C ft to over 50 ft (3 to 15 m). Length may vary to over 60 ft (18 m). The slope of a ramp should be between 12% and 15%. If the ramp slope is flatter than 12%, trailer wheel hubs have to be submerged while launching. Slopes steeper than 15% can be danger- ous unless the driver is very skilled (Dunham and Finn 1974). Dunham and Finn(1974) recommend that the ramp be paved to about 5 ft (1.5 m) below extreme low water level. There should be a level shelf of loose gravel at the end of the ramp to prevent a vehicle from sliding into the water if there is a loss of traction or brakes. The most common construction tech- nique uses a gravel foundation covered by a layer of concrete. The thickness of these layers ranges from 3 to 6 in (8 to 15 cm). Deep, square-shouldered grooves, perpendicular to the slope, should be pressed into the concrete during con- struction (Dunham and Finn 1974). This not only provides greater traction, but the ramp will last longer than one with a course finish without deep grooves. Submerged ramps, constructed of precast slabs, have provided the most satisfactory results. One construction method uses precast 6- by 12-in slabs placed 3 in (7.5 cm) apart. The gaps are filled with coarse gravel (Dunham and Finn 1974). Other methods have not prov- en as successful. Large concrete bricks and building blocks often dislodge if the subgrade is soft. Asphalt paving will not hold up well if used on the submerged part of the ramp, while unpav- ed ramps will deteriorate (Dunham and Finn 1974). Sufficient pier space should be provided for boarding and for holding the boat while launching. Piers are usually located on both sides of the ramp. Dunham and Finn (1974) recommend that a single-lane ramp be at least 15 ft (4.6 m) wide. They suggest that on a multiple-lane ramp, raised divider strips or marked lanes are not necessary and may reduce optimum usage during peak hours. Proper drainage should be provided for washdown facilities which are often used in saltwater areas. Oil, grease, and other pollutants may be washed off when cleaning the boat and trailer. For this reason, drains should be connected to a sewer system rather than returned into the water. Ramps should be placed in reason- ably quiet waters to minimize the number 74 If -a a; -CT LO S_ 1 — n3 •r— O I uZ S CM zr. • <_> c o 4- CD O QJ S- >> o to ai r\ +J >> S- A3 3 CQ o o (L) >» -M c ro > -Q ai S- ■> +J c o > ^ en C "£j O e • 3 t— (0 i — r— 'i— -C QJ • 1— r— > Q_ ^— E 3 •r— s: 1/1 • < _i , • UJ CO OT >> -O. QJ ^. -C =5 Q- cr> fO ., — S_ U. o> 76 of protective structures required. They should be placed in well-flushed areas to avoid the buildup of exhaust, petro- chemicals, and other pollutants. To fa- cilitate launching, it is desirable that currents be minimal. Ramps have many of the same placement constraints as so- lid-faced revetments. The section of this report on revetments should be re- viewed before evaluating the environ- mental compatibility of a ramp. Struc- tures located around the ramp, such as jetties, breakwaters and piers, should be designed to prevent adverse envi- ronmental impacts. Socioeconomic. Community use of a ramp is encouraged over individual ownership. This will help to limit the number of ramps. One ramp usually causes minimal adverse impacts. As the number of ramps in an area increases, the impacts become more intense. Poured concrete is probably the easiest, least costly, and most popular method of ramp construction. For the submerged ramp section, precast slab is less costly than poured concrete and provides better results (Dunham and Finn 1974). Secondary socioimpacts should be considered when evaluating the environ- mental compatibility of a ramp. These include all the impacts associated with increased human usage, such as conges- tion, littering, and discharging pollu- tants. Biological. Disturbance of wetlands should be minimized. During construc- tion, matting or vehicles designed to prevent soil compaction should be used. Extra filling of the wetlands should be avoided. Turbidity control devices should be used when necessary to pre- vent adverse impacts on the local aqua- tic community. Ramps should be con- structed in areas where minimal or no dredging is required. Review of the section on revetments in this report would help to determine the biological placement constraints for ramps. Construction Materials grating, asphalt, or any other material with a reasonable degree of structural integrity and resistance to decay in an aquatic environment. Expected Life Span The literature did not provide the specific information on the expected life span of ramps. Unpaved or submerged asphalt ramps generally will not last as long as concrete ramps. Summary of Physical and Biological Impacts Construction effects. The construc- tion of a ramp can cause suspension of sediments causing increased turbidity, reduction in productivity, smothering of benthic organisms, release of toxic sub- stances, and altered bottom habitat. A specified area of shoreline habitat is removed from the aquatic system and is replaced, in most cases, by less produc- tive habitat, particularly if the launch- ing ramp area is used heavily. The use of construction equipment will increase noise and air pollution. However, these impacts are usually slight and short in duration. Construc- tion equipment can also disturb a wet- land edge zone by causing soil compac- tion, which can have lasting adverse effects. Chronic effects. The greatest im- pacts are usually caused by related activities, such as dredging, protective structures, channel deepening, parking facilities, and increased human usage in the area. Boats and planes cause in- creased turbulence as well as petrochem- ical and noise pollution which can af- fect the diversity of fish and wildlife inhabiting the area. Ramps can make for- merly inaccessible areas accessible to fishermen and sightseers. This increased accessibility may result in modifica- tions to existing populations of organ- isms. It is also possible that the areater frequency of boat wakes may initiate or increase shoreline erosion along the waterway, causing a need for other protective structures. Construction materials may consist of qravel, shell, wood, concrete, steel of Cumulative effects. Construction a ramp will replace some intertidal 77 area. The as so dated parking facilities should be placed on the uplands. The impact of one ramp may be minimal. If the area becomes an attractive launch- ing area, then it may attract commercial facilities. The habitat alterations increase accordingly. Structural and Nonstructural Alternatives The purpose of most ramps is the launching and retrieval of small craft. This same function can also be perform- ed by a hoist which can pick the boat off a trailer and swing it into the wa- ter. Such a device usually requires a pier or other structure to allow access to water of sufficient depth. A sling would be more applicable in areas where there is relatively deep water close to shore. A marine way (dolly) is another viable alternative which avoids the nec- essity of constructing a pier and/ or dredging to reach water of sufficient depth (Figure 39). This launching tech- nique involves lifting the boat with a sling onto a platform mounted on rails (the dolly). Launching is achieved by running the boat down'the railed struc- ture and into water of sufficient depth. This technique has the advantage of al- lowing launching in areas with shallow slopes or at low tides. It is generally not feasible to cross extensive tidal flats with a ramp. Regional Considerations Most of the literature contained in- formation applicable to all of the coastal regions. There was some information specific to the north Pacific and Gulf coast (Coastal Regions 1 and 3). In the Puget Sound area of Coastal Region 1, siting ramps on "accretional or roll- back dry beaches" should be avoided due to possible changes in beach profile (Bauer 1973). Less than 4% of the shoreline in this area consists of dry beaches. If ramps are placed in this area, the protective structures should be constructed so they do not interfere with "beach drift action." Bauer (1973) suggests considering "flexible-contour bolt and hinge segmented ramp pads that can be adapted to beach profile changes, "and also recommended that ramps be located in between "drift sectors" or "independently operating erosion-trans- port-accretion beach systems." In the New Orleans District of the U.S. Army Corps of Engineers in the Coastal Region 3, the most common type of ramp consists of compacted gravel or shell covered by concrete (Carstea et al. 1976). These authors cave the di- mensions of a typical boat ramp as 10 to 12 ft (3 to 4 m) wide and 40 ft (12 m) long. A typical seaplane ramp is 25 to 30 ft (8 to 9 m) wide and 55 to 60 ft (17 to 18 m) long. Concrete and timber seaplane ramps are similar to the boat ramps. Shore profiles encountered in the various coastal regions will determine the design and feasibility of ramps and the desirability of utilizing alternate structures, such as slings and dollies. PIERS, PILINGS AND OTHER SUPPORT STRUCTURES Definitions A pier is a structure, usually of open construction, extending into the water from the shore. It serves as a landing and mooring place for vessels or for recreational or commercial uses. This definition of a pier includes tres- tles, platforms, and docks extending into the water for similar purposes. The definition does not include bridge piers. Floating structures anchored with pilings are sometimes called floating piers. Sometimes jetties, groins, and other structures built primarily for coastal protection purposes are incor- rectly called piers. A pile is a long heavy timber, steel, or reinforced concrete post that has been driven, jacked or jetted, or cast vertically into the ground to sup- port a load. A pile structure will nor- mally be an open structure where water can circulate between the individual piles or pile clusters. Sheet piles are steel or concrete sheets or slabs which are driven edge to edge in a straight row to form a bulkhead or wall. They can also be driven in circles, squares, or in other closed shapes to form bridge 78 U_ Q_ 79 piers, cofferdams, or caissons. Unlike individual piles, use of sheet piles nor- mally will not result in an open struc- ture. Structure Functions A pier usually functions as a land- ing and mooring place for vessels. Such a pier might also be used for loading or discharging cargo. Another function is to provide access to deep water from land. This is usually in conjunction with a landing or mooring place. A pier can also be used for boat launching and retrieval by means of a hoisting mech- anism located on the pier. A pier may also provide recreational usage, as for fishing or sight-seeing. Used for these purposes, a pier might also serve as a platform for restaurants or other com- mercial ventures. Separately or in clusters, pilings can perform several functions including: o Mooring vessels, anchoring floating rafts or floating platforms (Figure 40); Supporting aids to as lights, ranges, channel markers, (Figure 41); navigation, such day markers, or reflectors o Serving as the fenders or protec- tive features for piers, landings, bridges, or other structures. Pilings are also the basic element in many larger structures used for the mooring vessels and providing coastal protection. Site Characteristics and Environmental Conditions Piers extend into the water from a bulkhead or from the natural shoreline. They may extend in different directions to various depths, depending on naviga- tional requirements or their designated function. The location of a single pile or piling is also dependent on function. Piers, pilings, and pile-supported structures frequently occur with the marinas which are often located in estu- aries and bays. Placement Constraints Engineering. A typical residential fixed pier is 40 to 60 ft (12 to 18 m) in length. For a marina complex it is common for a pier to extend 2C0 to 250 ft or 61 to 76 m (Carstea et al. 1975). Piers may be straight or have "L" or "T" configurations (Figure 42). Piles are driven to a depth which will provide stability. This depends on the bottom characteristics of the site, as well as the lateral forces working against the structure. For example, a pier used for mooring purposes would be subjected to the forces of a vessel striking the side and would, therefore, have to support a greater lateral load than a pier used solely for fishing. The length of pile extending above the water is dependent on wave height and tide. According to Carstea et al. (1976) enough pile should be exposed to allow the decking to remain at least 3 ft (0.9 m) above the water and provide 3 to 4 ft (0.9 to 1.2 m) for mooring or handrails. Pile dimensions vary greatly. A mooring pile is usually around 10 in (25 cm) in diameter with 8 to 10 ft (2.4 to 3.0 m) exposed above mean high water (Carstea et al. 1975a). A dolphin is usually constructed with a center pile approximately 12 to 14 in (30.5 to 35.6 cm) in diameter, surrounded with piles from 8 to 10 in (20.3 to 25.4 cm) in diameter. A heavy wire rope is generally used to bind them together (Carstea et al. 1975a). Wood pilings should be treated to prevent decay and destruction due to marine borers (Figure 43). Treatment may include toxic surface coatings, pile sheathing, or creosote-coal tar impreg- nation. In areas where gribble, Limnoria, and marine clam, Pholas, attack are com- mon, the American Wood-Preservers' Asso- ciation (AWPA) C3 Standard recommends a dual treatment for wood pilings (Henry and Webb 1974). The addition of an insecticide may retard infestation (Lindgren 1974). Methods of protection are updated by the AWPA and should be consulted periodically. An open-pile structure is recom- mended over a solid-fill structure. The 80 O cn c •i — -£= o o rd to 3 •r— O »% C d (0 o S- 4-> u_ (/) cn • c: <=c •i — ^ • o r. ro >> c JO •i — S- -E ro Q. ^: (O S- c= CD o O +j +-> (/i o Cn_E e O. ■i — ^ 4^ TJ rd e 3 S- o OJ s- •^ cn Q.^: U cn n3 c: J3 •^ -i-> c ra ■I- o 1 — s_ U- (O • 3 o -s«i to c o ro o 3: to ■1— s_ o ^ >~> Q.-Q I C -C CD Q. Q. (O O S_ CD o • 4-> C\J O D- s- 3 • •1- c 83 '**- Figure 43. Gribble damage to a mooring dolphin in Key West, Florida can be seen near the water level. Photograph by E. L. Mul vi hill. 84 advantages include fewer adverse envi- ronmental impacts and ease of removal if so desired. Open-pile structures are also advantageous where substrate con- ditions are unstable. Adequate spacing of piles is important to prevent inter- ference with water and sediment move- ment (Bauer 1973). Site characteristics should influ- ence the design of a pier. According to the Coastal Plains Center for Marine Development Service (1973), floating piers can affect beach sand movement. They recommend open pile piers in the areas of significant littoral transport and longshore currents. Floating piers are suggested for areas where visual impacts should be minimized and where boat traffic would not be hindered by their presence. Another factor to consider is tidal range. Where the tidal range is above 4 ft (1.2 m), floating piers are recom- mended because they provide easier ac- cess to boats throughout the tidal cycle (Ayers and Stokes 1976). Floats can be removed in the winter to avoid ice dam- age (Carstea et al. 1975a). During the life span of pilings or a pile-supported structure, several changes usually occur which should be considered in the design. These changes alter the impact of forces acting on the structure. As marine growth increases on the pile, the diameter, roughness, and concomitant drag coefficient will in- crease. Scouring at the base of the pile will decrease pile support. Also, as piles are attacked by wood borers or as they corrode, structural damage will de- crease pile strength. (See U.S. Army Corps of Engineers 1973b for further information and calculations). The type of wave force occurring in the area should also be considered in the design. For example, breaking waves create a greater force on the pile than do nonbreaking waves. (U.S. Army Corps of Engineers 1973b should be consulted for further information and calculations.) The size, number, and placement of piling should be correlated to the various energy zones in which the pier is located. Socioeconomic. The number and size of pile-supported structures and piers should be minimized in a given area. The use of over-water locations for non- water-dependent structures should be discouraged (Carstea et al. 1975a). To limit the number of piers.it is suggest- ed that single piers be used coopera- tively by the community. This is par- ticularly stressed for subdivisions, motels, and multiple dwellings (South Carolina Marine Resources Division 1974). Structure size should be re- stricted to that which is necessary for designated purposes. Piers should not hinder public use of the water, navigation, or adjacent shoreline. Ex- tension of the structure beyond the mean high water line should be avoided (Car- stea et al. 1976). The socioeconomic impacts of public, private, or joint use of a pier should be considered. Biological. During construction, turbidity should be kept to a minimum and turbidity control devices should be used when necessary. Alterations of shoreline and littoral habitat should be avoided (Florida Game and Freshwater Fish Commission 1975). The placement of the structure relative to the sun, as well as the height and width of the deck, are important factors to consider. The structure should be placed high enough above the water or marsh surface to prevent shading. A narrow pier ex- tending from north to south would not produce as much shade as a wide pier running from east to west(Gifford 1977). The damage to wetlands can be minimized by constructing an elevated boardwalk to provide access to the dock or pier (En- vironmental Quality Laboratory Inc. 1977). The size, number, and placement of piling should be evaluated relative to the various biological zones over which the pier will extend. Construction Materials Piers, pilings, and structure sup- ports are generally constructed of wood, concrete, or steel. Decking, stringers, bents, and caps are made from wood, steel, or concrete members of various sizes (Figure 44). Construction materi- als that do not release toxic substances are preferred. 85 s- o s- a. >> -CI ai s- 0) +-> T3 a> .a o +-> 4-> 0) T3 T3 c to c o •r- c m a) o Q. >1 2 +J u a> i/i in • o CO S- c CJ o •1 — +J • • 1— «* ■a >tf c o QJ u 5- 3 ai 0> +-> Water quality should be considered when choosing construction materials. Areas with poor water quality will gen- erally not support populations of grib- bles or borers. If materials that are not resistant to their attack are utilized and water quality is significantly im- proved, there may be problems with premature structural failure. Expected Life Span Pilings of wood, steel, or concrete will generally have a life expectancy of 30 yr or more if they are treated. The environmental factors of an area greatly affect deterioration rates. Conditions of high salinity and high temperature, along with the boring organisms, will likely increase the deterioration process to some degree. Plans for removing the piling and other support structures after their ef- fective life span should be submitted when structure is proposed for con- struction. There are severe navigational problems in many areas of the United States, such as in New York Harbor due to the chronic decay and drifting away of pieces of old support structures. Piles or portions of piles remaining just below the water level also present navi- gational hazards. Summary of Physical and Biological Impacts Construction effects. Construction causes increased turbidity and sedimen- tation which, depending on severity, may reduce primary productivity, inter- fere with respiration of fish, alter the suitability of spawning areas, reduce bottom habitat diversity, and smother benthic organisms(Carstea et al. 1975b). Resuspended bottom sediments may re- lease toxic substances. Noise and vibra- tion, along with turbidity, may tempo- rarily drive fish or invertebrates from the area or cause behavioral modifica- tions. However, in some instances fish- es have been attracted to construction sites due to the suspension of benthic organisms. Chronic effects. Docks and piers can cause navigational problems and in- terfere with public use of the water. Conflicts may arise concerning adjacent land uses and area aesthetics. In areas where longshore currents, tides, and lit- toral transport are influential, float- ing piers can alter beach sand movement patterns (Coastal Plains Center for Marine Development Service 1973). Shading from pile-supported struc- tures may modify the water temperature and wetland habitat. Depending on the amount of shading, there may be a reduc- tion or absence of alqae and grasses under piers (Gifford 1977). But it should also be noted that piling and piers offer substrate for algae growth in some areas where algae did not for- merly grow because the bottom was below the photic zone or presented unstable sediment conditions. White (1975) indi- cated that single residential piers in fresh water are not likely to cause a significant reduction in phytoplankton production. Increased use of the area causes related impacts. Boat exhaust and do- mestic emissions can decrease water quality (Carstea et al. 1975b). Impacts may also be caused by increased fishing and litter disposal (Gifford 1977). Unless treated, the pilings and other structures provide suitable sub- strate for algae and new attachment sur- faces for invertebrates. These struc- tures also provide cover and feeding sites for fishes and may be used by var- ious birds for nesting or perching (Carstea et al. 1976). Sessile organisms on the exposed surfaces of a piling or other structure as well as the presence of the structure can attract motile or- ganisms, such as fishes, which feed upon the organisms or use the structure for shelter. Such areas generally offer very good fishing. Piles offer resting places and feeding observation posts for coast- al or marine birds, such as pelicans, kingfishers, herons, egrets, and cormo- rants (Carstea et al. 1976). The use of piles and piers by gulls seems to be a universal phenomenon. Channel markers are frequently used as nesting platforms by os prey. Cumulative effects. As the number of pile supported structures increase in a given area, the impacts on that area 87 will increase. The magnitude of adverse impacts may be dependent on the char- acteristics of the site and on the type of structures in the area. Open pile structures do not impede water or sedi- ment movement unless the pilings are spaced very closely. Sediment deposits will build up if too many pilings are lo- cated in a poorly flushed area or in one of slow water flow. The shoreline will stop littoral drift, fillinq with sediment (Carstea et al. 1976). The impact from shading increases as the area being shaded increases in size. Water temperature modifications and reduced primary productivity may have an adverse impact on the food chain. The absence of algae and grass- es eliminates hiding areas for fish and other organisms, but this may be offset by the new habitat created on the sub- merged structures (Figure 45). Structural and Nonstructural Alternatives The commonly noted function of a pier is to serve as a landing place for vessels. Piers, due to their open struc- ture, disrupt water circulation and bot- tom dwelling species much less than al- ternative solid structures, such as walls or sheet pile caissons. The most common alternatives for piers are: o For mooring vessels, an anchor or mooring buoy could be used. This is more common in New England and areas of extreme tidal range. o For mooring vessels and providing access to the shore, a floating pier could be used. This alternative might be aesthetically more desir- able but will probably cause in- creased shading and affect littoral transport. If the objective is to eliminate the pier, there are two nonstructural alter- natives available: o Combine the purpose of the pro- posed pier with that of piers in the vicinity to reduce the overall number of piers. o Use the launching ramps or other launching structures. Provide up- land storage of vessels. This, of course, is limited to smaller size vessels which can be conven- iently removed and transported on dry land. o Forrp community marinas to elimi- nate single piers at each water- front lot. Aside from the aesthetic consider- ations, loss of navigable water area, and-in rare instances-interference with sand movements, the impacts of open pier structures are minimal. Solid pier structures are generally less desirable and more costly. Elimination of piers by multiple use of existing piers or launching facilities appears to be the best alternative. Regional Considerations Very little information was found regarding regional specific aspects of piers, pilings, and other support struc- tures. The types of materials utilized will vary according to availability within each region. The length of piers may vary depending on the distance to deep water which is generally quite dif- ferent on the Gulf coast (Coastal Region 3) and in the Chesapeake Bay (Coastal Region 6) as compared to areas in Puget Sound (Coastal Region 1) and in New Eng- land (Coastal Region 7). The length of piles may also vary depending on the na- ture of sediments encountered in a re- gion. In areas where bedrock is close to the water body floor, piles would be shorter. The length of friction-type piles will also be affected by sediment characteristics. Infestation of piles by marine bor- ers tends to vary geographically. Grib- bles (Limnoria) breed only in tempera- tures above 57°F (14°C) and are preva- lent in southern California (Coastal Re- gion 2) and from the Gulf coast to the middle Atlantic (Coastal Regions 3, 4, 5, and 6) (Lindgren 1974). The abundance and growth rate of shipworms (Teredo) also varies geographically. Within a region, factors other than temperature affect marine borer populations. Heavily polluted areas may not be habitable by 88 Figure 45. Submerged structures offer substrate for the attachment of various types of marine organisms. Photograph by C. A. Francisco. 89 borers. In such areas, pilings will not have to be replaced as frequently as in non polluted areas. Fluctuating quanti- ties of fresh water in an estuary can also affect populations. If the salinity decreases sufficiently, borer populations will decrease. Physical factors may also have an effect on population density. A pile subject to high wave action will not support the population of gribbles that a pile in quiet waters will support (Hochman 1967). Constant high salinity and tropical temperatures accelerate the decomposition of chemicals used in creo- sote treatment (Lindgren 1974); there- fore, piling in such areas are more sus- ceptible to attack. BUOYS AND FLOATING PLATFORMS Definitions A buoy is an anchored or moored floating object intended as an aid to navigation, for attachment of vessels or instrumentation, or to mark the position of something underwater. If the buoy is to be used primarily for mooring ves- sels, it is called a mooring or anchor buoy. A platform is a horizontal flat sur- face usually higher than the adjoining area. A floating platform is a structure that floats on water and is held in place by anchors or piles or other mooring devices. A series of platforms in a line extending from the shoreline to deeper water would be considered a floating pier. Structure Functions Buoys are most commonly used as navigational aids to mark channels, shoals, harbor entrances, etc. Some- times buoys have lights, reflectors, or horns mounted on them. Buoys are also used as markers for sunken objects and' for suspending analytical instrumenta- tion, such as current, wave, or water quality monitoring equipment. Floating platforms are flat struc- tures which are generally larger buoys or floats. They are used for recreational purposes, such as swimming and diving, or commercial purposes such as selling fishing supplies. Larger platforms used for construction or drilling would nor- mally be considered as ships, barges, or hulls. Site Characteristics and Environmental Conditions Buoys are utilized in all types of energy environments, while floating platforms are usually used in relatively sheltered areas. Placements Constraints Engineering. The sizes and shapes of buoys and floating platforms depend on the function. For example, buoys or floats used in swimming areas or for mooring recreational craft would be smaller and of lighter construction than a buoy or float used in open water. The site and method of placement should be considered carefully. It is important that buoys and platforms be properly anchored according to their size and weight. Areas where bottom sediments frequently shift should be avoided. Water level fluctuations should be considered when designing an anchor system. Platforms, buoys, and attached vessels should not interfere with navigation. Socioeconomic. Platforms and buoys should not interfere with public use of the waterway. It is advisable to design them so that they are clearly visible to boaters. The presence of buoys and floats is generally accompanied by in- creased human usage of an area. The secondary impacts of the human usage should be considered. Biological. If drums or barrels are utilized as floats, those once con- taining toxic substances are not suit- able. It is advisable to coat foam floats to prevent chips and flakes from littering the water. To avoid contami- nation, all coatings must be dry before placing floats in the water. The sub- merged surfaces of buoys and floats and the anchor system offer habitat for var- ious types of attached organisms. They also supply refuge for various types of fishes. 90 Construction Materials The flotation material for floating platforms and buoys generally consists of polystyrene, ployurethane or hollow steel, aluminum, fiberglass, or concrete structures. The most popular type of floats are polystyrene and polyurethane foam. They should be coated with a pre- servative to prevent deterioration and attachment of marine flora and fauna. The coating may consist of poly vinyl- acetate emulsion or dense polyurethane (for polystyrene), fiberglass and resin (for polyurethane), plaster, or concrete (Dunham and Finn 1974). When using polyurethane, the monocellular type should be used, as it is the only type that is nonabsorbent. Extruded polysty- rene (Styrofoam) is totally impermeable by water and may be preferred over expanded-pellet polystyrene (bead- board), which is more susceptible to water penetration (Dunham and Finn 1974). Polyurethane is naturally hydro- carbon-resistant. Polystyrene can be made hydrocarbon resistant. This is an important factor to consider when locat- ing structures in an area susceptible to petroleum products. In the past, hollow floats or fiberglass or metal were used. Hollow-shell floats are more susceptible to leakage and are being replaced by shells filled with foam. Wood flotation devices are used in some areas of the country, such as the Pacific Northwest. Platform decks may be constructed from wood, concrete and plastic materials. Anchor systems may be made from rope, cable, or chain. Anchors can be patent- ed anchors of steel or can be made of concrete blocks and various makeshift things, such as junk auto parts. Expected Life Span The life span of buoys and floating platforms was not addressed in the lit- erature. Materials treated against ma- rine growth and corrosion will last long- er than untreated materials. The sever- ity of environmental conditions where they are utilized will greatly affect their longevity. Summary of Physical and Biological Impacts Construction effects. The effect of the installation of buoys and float- ing platforms is minimal. Chronic effects. Shaded areas caus- ed by floating structures and the areas occupied by their anchors are usually small and generally would not be expect- ed to result in measurable effects. Shading from platform decking may result in a small decrease in primary produc- tivity. The impact is dependent on the size of the structure. Buoys and plat- forms provide habitat for sessile organ- isms and cover for fish. Pelagic game fish are attracted to buoys and floats. They are, therefore, popular sport fish- ing spots. Cumulative effects. Cumulative effects were not considered in the lit- erature. It is apparent, however, that there can be aesthetic and navigational problems created if the number of float- ing objects is allowed to proliferate. Structural and Non-Structural Alternatives One alternative to buoys used for navigation aids or markers would be pile structures. Mooring buoys could be re- placed by fixed structures such as dol- phins or piers. The necessity for buoys could be eliminated by installing a launching ramp and requiring land stor- age of the boats. Regional Considerations Most of the information in the lit- erature is applicable to all of the coastal reqions of the United States. The Buffalo District of the U.S. Army Corps of Engineers (undated a) (Coastal Region 8) proposed that general permits be issued for navigation, mooring, and special purpose buoys and floating plat- forms in New York State. Specific re- strictions for that area included limit- ing a deck surface area to not more than 200 fr (61 rrr) and restricting platform extension to no more than 100 ft (30.5 m) waterward from the high water line. HARBORS FOR SMALL CRAFT Definition A harbor is a protected water area 91 offering a place of safety to vessels. Natural harbors are those where the protection is provided by the natural geography of the area. Artificial har- bors are those where natural protection does not exist (i.e., on an open coast line) or where substantial structures are required to provide adequately pro- tected water areas. Small craft harbors are protected areas whose depth and maneuvering area limit usage to small craft. Harbors specifically designed or constructed for fishing boats are includ- ed in the general definition of small craft harbors. Marina is used synony- mously with small craft harbor, but gen- erally refer to harbors for pleasure craft. Although the word port is some- times used interchangeably with harbor, it is clearer to use port to signify a place, usually both a harbor and town, suitable for landing people or goods. Technically, a harbor for small craft could be the water surface in a naturally or artifically protected area in a bay, lake, or estuary. However, as commonly used in the United States, a small craft harbor also includes the nec- essary features for the safe navigation and mooring of small craft. This would include the following features: o A natural or man-made entrance channel of sufficient width and depth for traffic use; o A natural or man-made basin of sufficient depth and size for an- choring or mooring craft; o A breakwater surrounding the basin to provide protection from natural waves and swells from passing vessels. It can also pro- vide protection from swift cur- rents. The breakwater might con- currently function as a jetty to assist in maintaining depth in the entrance channel or as a groin to prevent sediment or sand from en- tering the basin. The breakwater might incidentally serve as an access road or path to the harbor or to the waterway in which the harbor is located ; o A system of piling, floats, piers, anchor buoys, or other devices for mooring small craft. A small craft harbor might also in- clude the following items: o Special facilities, such as piers for fueling and taking on provi- sions; o A ramp or launching device for placing small craft in the water and removing them; o Backup land for parking vehicles and providing access to the harbor facil ities. There is no exact definition as to how many of the above features are im- plied by "small craft harbor." But, many of the structures considered in this re- port are common components of small craft harbors (Figures 46, 47, and 48). Small Craft Harbor Functions The function of a small craft har- bor is to provide shelter for small boats and, in some cases, to supply sup- port facilities for the activities car- ried out by the boats. Site Characteristics and Environmental Conditions Small craft harbors usually occupy several tidal zones extending from the terrestrial zone through the subtidal zone when the accompanying parking fa- cilities, launching ramps, and breakwa- ters or jetties are included. Small craft harbors are more com- monly located in bays, estuaries, inlets or coves, rather than on open coasts. Due to recent concern over construction in the intertidal and near intertidal zones and the diminishing number of feasible sites, marinas are now frequent- ly dua out of upland areas (Carlisle 1977)/ Placement Constraints Engineering. Environmental condi- tions of the specific site should be 92 c: +-> s_ O o a. 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Such changes can affect marsh plant ecology. An example is the different elevation requirements of Spartina alter niflora and Spartina patens in northeastern marshes. Causeways way possibly result in disruption of fish and whale migration. According to Brisby (1977), whale mi- gration was slightly disrupted by the causeway leading to Rincon Island, California. Cumulative effects. The cumulative effects of bridges and causeways are referenced in the literature about the Florida Keys. The case study of this area should be consulted. Structural and Nonstructural Alternatives Bridges and causeways can be de- signed to respond to the physical and environmental surroundings in which they are built. Bridges can be placed on piling or piers shaped and spaced to provide minimum interruption of altera- tion of water flow. Bridge spans can be designed with longer lengths to re- duce the number of piers or support structures in the water; however, a long span length may make the struc- ture more costly to build. Causeways can be designed with culverts or open channels through the structure to allow water circulation. Causeways can be replaced by open pile structures instead of fill to allow nearly unhindered circu- lation of water. There are several nonstructural alternatives to bridges. One, of course, is routing of the highway or railway over existing bridges or by circuitous routing not requiring a bridge. Another nonstructural alternative is to use a ferryboat instead of a bridge. Tunnels and rerouting are also al- ternatives to the causeways, although a tunnel is so much more costly than a causeway that it is a theoretical rather than a practical alternative. Since the causeways normally cross marshes or shallow water, it is unlikely that a ferryboat would present a viable alter- native in many instances. Structures associated with ferryboats, such as piers, also have environmental impacts. In addition, the convenience of a bridge relative to a ferryboat is obvious. Regional Considerations The only specific regional consid- erations mentioned in the literature were in reference to the Overseas High- way through the Florida Keys in Coastal Region 4. The case study should be consulted for further information. Besides various methods of design- ing and building a bridge to alter the impact, there are some alternatives avail- able. The most common structural alter- native to a bridge is a tunnel. After construction, a tunnel provides no inter- ference to water flow or circulation and no interference with the substratum or intertidal zone. If the tunnel is placed in a dredge trench, there might be sub- stantial alteration of the substratum during construction, as well as other problems normally associated with the dredging or underwater excavation. As a general rule, tunnels are significantly more expensive than bridges. 106 CASE HISTORY STUDIES This section contains summaries of cases where shoreline structures have been installed and the subsequent mod- ifications to the environment. Case his- tories were selected to cover each of the coastal regions in this study and, where feasible, the structures which cause permit review personnel in each region the most difficulty. Some of the case histories are well-documented, and others are very sketchy. In some cases no information existed and hypothetical case histories were formulated. In each instance the case histories reflect the type of concerns that should surface in the permit review process. CASE HISTORY - SMALL CRAFT HAR- BORS IN COASTAL REGION 1 -NORTH PACIFIC Information pertaining to a specific harbor and location is not sufficient for the presentation of an actual case his- tory in Coastal Region 1. A significant amount of the literature about small craft harbors in Coastal Region 1 is re- lated to marina design and its effect on water quality and salmon migration. Four marinas in the Puget Sound area of Washington State will be compared to illustrate the impact of marinas in the Coastal Region 1. The four marinas are Edmonds Marina, Des Moines Marina, Kingston Marina, and Shilshole Marina. Maximum wave height in this area is approximately 6 ft (1.8 m). The tidal range is around 10 ft (3 m). Northwest- erly winds are common in the summer (Rickey 1971). Edmonds Marina consists of two at- tached rubble mound breakwaters pro- tecting two marina basins (Figure 53). The entrance is located between these breakwaters. The shoreline is bulkhead- ed and two timber pile breakwaters ex- tend from this bulkhead shoreward of the entrance separating the two basins. The basins are dredged to -12 ft MLLW or -3.7 m (Nece et al. 1975). There are 825 boat berths in the two basins and about 25% to 30% of the surface is shaded by floating piers. The munici- pal primary sewage treatment plant out- let is located just north of the marina and another large storm drain outlet is located to the south. The parking lot storm drains empty into the basin. Heiser and Finn (1970) indicated that there was evidence of "impound- ment"; but because of the location of the marina and the large entrance, the tidal exchange was adequate for reason- able water quality. Problems might arise from a spillage of petroleum materials within the basin because the materials would be held in the marina by winds blowing north or south toward the sides of the breakwaters. Observations by Heiser and Finn (1970)showed that pink and chum salmon fry were concentrated inside the marina in greater numbers than along adjacent natural shorelines. They do not know if the harbor acted as a trap for the fry or if they prefer- red the confines of the harbor. Des Moines Marina consists of a single basin with a rubble mound break- water leaving a dredged channel open- ing facing north. The basin is dredged to -12.6 ft MLLW (-3.8 m). The surface area of the marina is approximately 20 acres (8 ha) and about 25% of the sur- face is shaded by floating piers (Nece et al. 1975). Two residential storm drains and the parking lot drains empty into the basin. The location of the en- trance is not conducive to the tidal ex- change. Northerly winds are common in the summer and will cause interference with the outward movement of the water (Rickey 1971), resulting in stagnation at the southern end of the marina basin (Heiser and Finn 1970). Kingston Marina consists of a dog- leg rubble mound breakwater extending from the north shore, then angling twice at approximately 45° to protect the front of the marina. The south side of the marina consists of a large en- trance. Because of this large opening, the water quality of the marina is rela- tively good. The large open area allows adequate tidal exchange and good move- ment of surface water out of the marina with northerly winds (Heiser and Finn 1970). Heiser and Finn (1970) observed 107 Q < UJ UJq; \^ X o \-Juj \ * z °"< \ i Z3 >** \ CD o UJ* \ to eo< ^UJ UJ 1 1 Q i-eo O z 3 3* a. Ouj 1 1 caV\\ /DETACHED RUBBLE // \\ ^MOUND BREAKWATER ^= QJ UJ coif eo< 3uj CO °^ ujO -■Z \\ o° \\ Ql \v Q \\ Z \V. to ^v^/^\,^ UJ ^"^-'" 2 ^z \ (_> -t-> o c a> i- to to < E IB 7 S- cr> OL T en i/l c • •r— __ sz T 10 in fO .2 ft T3 s= 3 o OO +-> (U CD 3 Q. C •i — to C C7> •r— to CD "O res c •^ S- (O E +-> < c z <1J •" Q) ce 4- < 4- 5 7 s_ O 3 o ►- u_ to O 7 oo — Lf) * , ia e -o S- C • X CO •«-> ■i- >, Q. CO t/0 CD +-> C S_ fO 3 CD O O O O >>-=: ro Q- CO n3 S- u> • o e -i-> o o CD-C > s- #» •r- C X3 +-> CD C +-> <_> ro CD i — •r-> +-> +-> fO S_ -i; O O >, Q- O +-> E 4-> •» (O CD +J i — ••—> U i — •i~ •r- -C s_ 1— 4-> +-> 13 to O •1 — • I/) Q ^1- un cd S- .c (U CD +-> CD 5- c = E • »— CD O en •r- S_ C LL. 4- LU 110 was narrow, with a dangerous shoal and rapid tides. This situation continued through the nineteenth century. In 1888 the U.S. Army Corps of Engineers re- ported that there was no reason to im- prove the channel entrance. Fifteen years later, the north jetty was propos- ed to control the ebb current (Terich and Komar 1973). The north jetty was completed to a length of 5,400 ft (1,646 m) in 1917 at a cost of $776,000. It incorporated 429,000 tons (389,180 met- ric tons) of stone. It was extended 300 ft (91 m) in 1933 (Terich and Komar 1973). No cost information on the exten- sion was found. By 1921, four years after the north jetty was constructed, the channel had migrated to a new position against the ietty, and dredging was later required to keep it open (Kieslich and Mason 1975). The hazardous channel conditions ultimately led to the construction of a second, longer jetty on the south side of the entrance beginning in 1969 (Terich and Komar 1973). The south ietty, completed in 1974, cost about $11.3 million (Anderson 1975). Total volume of stone used is not known, but Anderson (1975) reports that it was considerably more than had been esti- mated. This underestimation of material required was largely due to problems encountered during construction. The jetty was built on the natural sand bottom. Though allowances were made for moderate sand loss due to the crosscurrent scouring during construc- tion, the magnitude of this loss was grossly underestimated. At the halfway point in construction, the entire quan- tity of bedding material had been used. Strong currents around the advancing end of the jetty were washing out bed- ding material and sand to a depth of 30 ft (9 m) for about 300 ft (91 m) beyond the jetty tip. This problem was solved in part by eliminating bedding material and dumping large 200-lb (90- kg) to 5-ton (4.5-metric ton) core stone direct- ly on the sand bottom and by working double shifts to accelerate the construc- tion process (Anderson 1975). Kieslich and Mason (1975) state that design objectives for jetties are to minimize undesirable effects of wave ac- tion on navigation and to eliminate the necessity for artificial channel mainte- nance. The latter is usually achieved by either preventing littoral drift from entering a channel or concentrating ebb currents so that their natural scouring action is enhanced. Apparently neither of these objectives has been achieved by the Tillamook jetties. The channel required dredging a few years after the north jetty was constructed (Kieslich and Mason 1975). In 1975, the Portland District, U.S. Army Corps of Engineers prepared an environmental impact state- ment for miscellaneous activities, includ- ing channel dredging, in Tillamook Bay. Another factor in the construction of the south jetty was local desire for a means of halting erosion of Bayocean Spit. Following the extension of the north jetty, erosion apparently acceler- ated on the long, narrow sand spit (Terich and Komar 1973). Few records were kept previously, so it is unknown whether or not the construction of the north jetty increased erosion of the spit. It is known that the three-fathom contour moved 1,500 ft (457 m) closer to the spit between 1885 and 1939. This caused increased nearshore wave energy and concomitant erosion potential (Terich and Komar 1973). Historical records show definite changes in the shoreline both up and downdrift of the bay mouth following construction of the north jet- ty. Up drift sand accretion occurred behind the jetty, while the shoreline of the downdrift spit retreated due to ero- sion (Komar et al. 1976). The spit eventually became so narrow that a storm in 1939 opened gaps which allow- ed the sea to enter the bay. In 1952, a storm broke through and left a 0.8 mi (1.2 km) breach near the broad south end of the spit. This was later diked, but for some time there were essentially two entrance channels into the bay (Terich and Komar 1973). Recent infor- mation seems to indicate that erosion of the spit has slowed since construction of the south jetty (U.S. Army Corps of Engineers, Portland 1975). The effects of the Tillamook jetties on the biota of the area can only be inferred since no quantitative before- Ill and-after studies were made. Altered currents within the estuary may have caused changes in sedimentation, salin- ity, and water temperature patterns. Erosion probably eliminated some sandy shore habitats, while accretion created others. The jetties provide a substrate for sessile and cryptic organisms and fish communities associated with the submerged structures. Turbidity, caused by scour, may have affected organisms in the area, and the confined channel may be a less than optimum environment for migrating smolts. In relation to the human environ- ment,the presence of the jetties has ap- parently enhanced the area as a beach recreation and sport fishing area. Stabi- lization of the entrance channel allows fishing boats access to the harbor and the sandy area behind the north jetty provides clamming and fishing. The jetties are extensively utilized by fish- ermen. Erosion of the Bayocean Spit has been blamed on the presence of the north jetty, so the loss of habitat and real estate may be a negative impact. Channel maintenance dredging, in- clusion of weirs in jetties, bypassing of sand, or no action at all are alterna- tives to the construction of jetties such as those of Tillamook Bay. If the inlet is to remain navigable, the no-action alternative is eliminated from considera- tion. Channel maintenance dredging dis- turbs the existing environment. Dispos- al of dredge spoils on land or in the estuary is generally considered unac- ceptable and sea disposal preferable. Thus, sand would be permanently lost from the area. Sand placed on down- drift beach would cause some temporary loss of habitat of intertidal organisms, but might slow erosion on the Bayocean Spit. Turbidity and resuspended sedi- ments could affect water quality. Fre- quent dredging would be necessary and costly. If an inlet must be stabilized, it appears that no acceptable alternatives to jetties exist. The impact of jetties on the physical and biological environment could be lessened by reducing their in- terruption of littoral drift. Weirs, plac- ed at intervals along a jetty's length, and bypassing of sand would serve this purpose. This would reduce the erosion of the shoreline downdrift and accretion updrift. Whether the weirs would lead to the necessity for more frequent chan- nel dredging would require site-specific study. Careful studies of potential effects should be conducted before jetty con- struction is begun. Too often an inlet has been stabilized without thorough knowledge of effects on other aspects of the local environment. CASE HISTORY ■ COASTAL REGION CALIFORNIA BULKHEADS IN 2 - SOUTHERN Relatively little information was available concerning the bulkheads in Coastal Region 2, except some general observations on the effects of bulkhead- ina and the other protection measures (Ploessel 1973, Carlisle 1977). Bulkheads and seawalls are used in California for the same purposes as elsewhere in the country. They contain landfill and protect the bulkheaded shoreline from erosion. They also pro- vide mooring. Effects of bulkheads and seawalls on the biota of California are not well documented, but a high incidence of red tide has been observed in harbors which have poor water circulation as a result of bulkheading (Carlisle 1977). There is obviously a loss of habitat in areas which are filled, and intertidal communities may be severely affected if a bulkhead is built below mean high water. Scouring at the foot of a bulk- head is a physical impact which affects the benthic community in the vicinity of the bulkhead. The vertical wall of the bulkhead may also inhibit migration of certain organisms from the water to the shore (Carstea et al. 1975a) or along the shoreline. Bulkheads and seawalls can have significant effects on human use of an area. Bulkheads in industrial or resi- dential areas may increase boat traffic by providing mooring facilities. Seawalls on the open coast may restrict human 112 access to beaches and may result in erosion of existing beaches. The ecological effects of a bulk- head or seawall may be considerable. Shorelines are often inherently unstable and the structure of their biological communities reflects this instability. The erosion which bulkheads are de- signed to halt is a natural process to which the communities are adapted. Halting the erosion will alter the natural communities. Alternative structures, such as revetments of riprap, will also alter natural communities by providing a different type of substrate. However, riprap has several advantages over sea walls. Erosion of areas on the borders of the riprap may not be as severe as with bulkheads or seawalls. The major advantage of a vertical structure over a properly installed revetment is the pro- vision of mooring facilities or cosmetic treatment of the shoreline. When the bulkheads or seawalls are proposed in this coastal region, adequate consideration must be given to a num- ber of important factors. First of all, given the existing littoral processes, determine where erosion and accretion will occur after installation of the struc- ture. If erosion or accretion in an im- portant habitat or navigable waters will result, then one can anticipate additional maintenance needs, such as beach nour- ishment or dredging, or the construction of additional structures. Secondly, bas- ed on the expected physical impacts of the structure, determine which aspects of the biotic community will be affected and the extent of the impact. For in- stance, if an area containing the marsh grass is to be bulkheaded and filled, many biotic effects can be predicted - such as reduction in the amount of pri- mary productivity by marsh grasses and, consequently, a reduced crop of living and dead plant tissue for con- sumption by other organisms. Valuable spawning or rearing areas might also be removed. Each situation is unique and must be considered separately. CASE HISTORY - SMALL CRAFT HAR- BORS IN COASTAL REGION 2 - SOUTHERN CALIFORNIA A considerable amount of informa- tion is available in literature on small craft harbors in Coastal Region 2. Ben- thic studies were conducted by Reish (1961, 1962, 1963) from May 1956 to April 1962, regarding the benthic fauna and fouling communities in Alamitos Bay Marina following construction. These studies will be used as a base for a case history of Alamitos Bay Marina. Alamitos Bay Marina is located in Alamitos Bay in Long Beach, California. The first marina basin was dredged from land beginning in late 1955. The basin was dredged to a depth of -12 ft (-3.7 m) mean low water and had a sur- face area of 12.5 acres (5 ha). In early 1956, after bulkheads had been con- structed, the basin was filled with water. Further dredging was conducted in the central part of the basin. Boat mooring began in early 1957. Reish (1961) reported results of benthic sam- pling from May 1956 to August 1959. The substrate of the first basin was originally gray clay containing bits of mica. In late 1957, black sulfide mud was discovered at one of the sampling stations. By summer of 1958, all sample stations had a layer of black mud con- taining a sulfide odor. This may be at- tributed to poor circulation causing a decreased oxygen supply. The number of benthic specimens collected varied quite noticeably during the first 2.5 yr of study with an increase after the ba- sin filled with water followed by a pre- cipitous decline. The lack of water cir- culation may have been the cause of the decrease in population that occurred in the spring of 1957. Low oxygen levels were discovered above the basin floor. Another possible cause of the benthos reduction is pollution caused by the boats in the basin. Benthic species com- position within the basin was relatively constant over the rest of the study pe- riod and there was no indication of suc- cession. Sixty percent of the species and 87% of the specimens collected were polychaetes (Reish 1961). In 1959, the dredging of three more basins and the main channel be- gan. Basins were dredged to -12 ft 113 (-3.7 m ) mean low water, while the channel was dredged to -15 ft (-4.6 m) mean low water. Cement bulkheading and rock riprap were used for the sides of the marina. Benthic studies were conducted by Reish (1963) from August 1959 to April 1962, following the comple- tion of dredging of the three additional basins and the channel. No benthic animals were found in the first samples taken following the dredging; specimens were found in samples taken in Septem- ber 1959. Species numbers increased rapidly for the first 9 mo after that time, then held constant in the channel for the following 14 mo (Reish 1962). Over 50% of the species collected were polychaetes. Over the period of the study, no significant decrease in popu- lation occurred after about 1 yr in the first basin and in the inward portions of the additional three basins. This drop in species was related to a drop in dissolved oxygen and appearance of sul- fide odor. These findings reinforced Reish's theory that poor water circula- tion was the cause of the decrease, since the water circulation in the chan- nel was not restricted. According to Reish (1963), it apparently takes about 1 yr for the effect of limited water movement to alter the benthic environ- ment of a newly established marina. No successional patterns of benthos were observed . Reish (1961) also observed that succession of attached organisms did occur on the floats in the marina. The apparent climax community of My til us and Ulva was noted after the floats had been in the water for 6 mo. Up to 30 associated species might have been pre- sent. Reish (1962) notes that succession on solid substrates in the southern Cali- fornia waters is more rapid than what has been observed in other geographical areas. This may be due to longer breed- ing seasons and relatively restricted annual water temperature ranges. Because of the apparent correlation between benthic population decrease and poor water circulation, it is recommend- ed that measures be taken to maintain proper circulation in marinas. Poor wa- ter circulation affects the benthic com- munity and may also adversely affect fishes, shellfishes, and other aquatic life in the area. CASE HISTORY - BULKHEADS IN COASTAL REGION 3 - GULF OF MEXICO Within the Gulf of Mexico, a num- ber of studies are available documenting the effects of bulkheads or seawalls on certain components of an ecosystem (Corliss and Trent 1971, Gilmore and Trent 1974, Mock 1966, Moore and Trent 1971, Trent et al. 1972, 1976). These studies are primarily concerned with structures on the coast of Texas, but the results are generally applicable along the Gulf coast of the United States. The purpose of bulkhead or sea- wall construction in this region is to provide protection of upland areas from erosion and also to provide waterfront real estate. This latter function is achieved by constructing a bulkhead along a vegetated shoreline and then filling the area behind the bulkhead to provide land for development. Such artificial creation of real estate is com- mon in Galveston Bay, Texas, and in Florida. Bulkheads also provide mooring facilities . The creation of bulkheaded water- front housing developments in this region has clear socioeconomic signifi- cance, regardless of the level of envi- ronmental impact. Their success in pro- viding desirable real estate is obvicus. Alternate structures are generally not considered because of the economic ben- efits gained from filling behind a bulk- head or seawall. Their effects on coast- al processes and the biota require more detailed study. Trent et al. (1976) studied an area in the West Bay of Galveston Bay, Tex- as, which had been a natural marsh before bulkheading. The marsh was altered by channelization, bulkheading, and filling. The altered area consisted of a series of dead end canals with houses built on the strips of land sepa- rating the canals. Approximately 111 acres (45 ha) of emergent marsh vege- tation (pri marly Spartina alterniflora), 114 intertidal mud flats, and subtidal areas were converted into about 79 acres (32 ha) of subtidal habitat by the develop- ment (Trent et al. 1976). Phytoplankton production, oyster production, benthic macroin vertebrates, fish, and crustacean abundance were studied in an open bay area, the bulk- headed canal area, and in adjacent nat- ural marsh area. Primary production of phytoplankton was higher in canal than marsh areas, and production in both areas was much higher than in the bay (Corliss and Trent 1971). Oyster set- ting was 14 times greater in the natural marsh than in a canal area. The faster growth and lower annual mortality rates in the natural marsh were also reported by Moore and Trent (1971). Benthic macroin vertebrates were numerically slightly more abundant and volumetri- cally over twice as abundant in the marsh than in the canals. The lowest abundance was in the bay. However, when individual phyla were considered, numeric and volumetric abundance var- ied by area (Gilmore and Trent 1974). More finfishes and crustaceans were caught in the marsh than in the canals and catches were much higher in both areas than in the bay. Brown shrimp (Penaeus aztecus), white shrimp (P. setiferus), and spot (Leiostomus XJLD.- thurus)~ were most abundant in marsh; and largescale menaden (Brevoortia pat- ron us) .Atlantic croaker (Micropogonias undulatus) and bay anchovy (Anchoa mitchilli)~ were most abundant in canals (Trent et al. 1972). These six species comprised 89% of the' total catch. Mock (1966) compared penaeid shrimp produc- tion in a bulkheaded and natural area in another area of the Galveston Bay system. He found greater shrimp pro- duction in the natural habitat. Numerous physical differences be- tween the altered and unaltered marsh areas were noted. Substrates in the canal areas had a higher silt and clay content than the marsh, and the amount of organic detrital materials in marsh substrate was twice that found in the canals (Trent et al. 1972). Average temperature, salinity, total alkalinity, and pH were similar between the marsh and canal areas. The averaoe dissolved organic nitrogen was highest in the marsh and may have been due to cattle grazing near the marsh. Average total phosphorous was highest in the canals of the housing development, but was variable across time. Average levels of dissolved oxygen and surface turbidity were lowest in the canals, and dissolved oxygen levels dropped to extremely low levels at sampling stations farthest from the bay during the summer months. In general, productivity was high- er in the marsh than in canal areas and lowest in the open bay. Plankton blooms followed by low levels of dissolved oxy- gen, high nutrient levels, fish kills, and depressed oyster, benthic macroin- vertebrate and shrimp production in the summer months indicated the presence of eutrophic conditions in canal areas of the housing development. Moore and Trent (1971) noted that eutrophic con- ditions probably develop more rapidly in housing development canals than in nat- ural marsh areas because of high nutri- ent levels, increased phytoplankton pro- duction, and a reduction in water circu- lation and exchange. Reduced productivity in bulkhead- ed canals may not be directly attribut- able to bulkheads, but rather to the in- creased human usage of the area and the removal of marsh habitat. Human use of bulkheaded and filled areas is generally increased in terms of housing and boating. From a biological standpoint, bulk- heading in this coastal region alters existing communities and may eliminate some species entirely. The energy base of the community changes considerably with the elimination of marsh grasses. There are no satisfactory alternative structures for the creation of new real estate. However, existing land may be protected from erosion by the use of revetments or by planting vegetation. When placing bulkheads or seawalls, it is desirable to locate them as far upland as possible, preferably above mean high water. CASE HISTORY - COASTAL REGION MEXICO CAUSEWAYS IN 3 - GULF OF 115 The information available about causeways in Coastal Region 3 is very limited. Clewell et al. (1976) conducted a study of seven fill-road sites on the northern Gulf coast of Florida. Sites were located in five tidal salt marshes in Wakulla, Taylor, and Dixie counties. This study will be used as a case his- tory of causeways in Coastal Region 3. According to Clewell et al. (1976), tidal marshes in the area studied exist "where waves penetrate only during se- vere storms and hurricanes." Marshes are periodically flooded as a result of tidal sheet flow. The height of high tide is dependent on lunar positions and is, therefore, variable. A marsh located at a higher elevation may not be inun- dated as often as one at a lower eleva- tion. The sites that are inundated daily usually have a uniform salinity similar to that found in tidal creeks or rivers. Sites not flooded daily have a higher salinity due to evaporation. Sites high enough in elevation to receive more fresh water from runoff and rain than the salt water inundation have low salin- ities. The vegetation is dependent upon the salinity levels of the site. The distribution of three mollusc species sensitive to particular regimes of salinity and inundation were studied. These species reacted to disturbances by alterations in density. Plant zonation was also determined along with salinities and elevations. The Porter Island site involves a paved fill-road built 22 yr prior to the study that traverses a 1.5-mi (2.4-km) long marsh protruding into Apalachee Bay. The fill is not culverted. The only opening consists of a 25-ft (7.6m) long bridge span. Fill canals run along the entire length of a roadway on both sides. The study revealed that other than the presence of the roadway and canals, the marsh environment was not adversely affected because tidal inunda- tion occurs independently on both sides of the unculverted marsh since it is bounded by Apalachee Bay on both sides. The Levy Pond site consists of a marsh separated from a creek by an unculverted fill-road built 38 yr prior to the study. The roadway has blocked the sheet flow so that the marsh (Levy Pond) contains fresher water than the tidal creek on the other side of the fill- road. Photographs taken from years after construction showed that various salt-intolerant plant species have grown in Levy Pond. No vegetation can be seen in similar ponds on the seaward side of the road. At the time of the Clewell et al. (1976) study, Levy Pond was "completely choked with cattails, sawgrass, and other emergent marsh species, all characteristic of fresh water or very slightly brackish habitats." The Evans Creek site contains a fill- road, built 38 yr prior to the study, that traverses a tidal creek (Evans Creek) approximately 0.5 mi (1.3 km) from its mouth. The salt marsh on the landward side is isolated from the creek except for a box culvert (5 x 5 ft or 1.5 x 1.5 m). The creek was ditched to facilitate tidal inundation of the land- ward side of the road. Only slight dif- ferences in salinity, animal density, and vegetational zonation were discovered between the landward and seaward side of the fillroad. Clewell et al. (1976) state that it is uncertain if these dif- ferences are due to the roadway or if they always existed between the two areas. It is suggested that the ditching "increased the frequency of tidal flood- ing but decreased the length of time that the marsh was inundated in each tidal cycle." They suggest that culverts might be substituted for ditching to maintain more natural inundation and drainage in such marshes. The Cedar Island study involves a north and a south marsh. The two sites are landward of a fill-road, built 8 yr prior to the study, that runs parallel to the coast 0.3 mi (0.5 km) inland. The north site can only be inundated by the sheet flow. Only one culvert opens up to the seaward side of the road. A ditch and tidal creek flowing into a cul- vert allow inundation at the south site. The results of the study indicate that sheet flow was blocked at the north marsh except when severe storms occur- red. This allowed for the invasion of salt-intolerant species. The effects of 116 the fill-road and ditching in the south marsh appeared to be similar to the Evans Creek site. Two sites were also investigated at Cow Creek. Both of the sites are land- ward of a fill-road completed 4 yr prior to the study and paralleling the coast. What is referred to as the "open area" is 1 mi (1.6 km) from the Gulf along Cow Creek. The study area is connect- ed to the seaward side by a 6-ft(1.8-m) wide culvert. Salinity, plant zonation, and pattern and abundance of molluscs were the same on both sides of the road and are, therefore, assumed to be unaf- fected by the fill-road. What is referred to as the "closed area" is approximately 0.8 mi (1.3 km) from the Gulf. A 3-ft (0.9-m) wide and 12-ft (3.7m) wide culvert facilitates the drainage. Fill canals are located on both sides of the roadway. Sheet flow ap- pears to be restricted from the land- ward side of the roadway, as evidenced by the presence of salt intolerant spe- cies. Clewell et al. (1976) state that the canals are intercepting much of the incoming tidal water. Clewell et al. (1976) conclude that if the tidal flow through a fill-road is unrestricted, marsh will not be signifi- cantly affected, other than within the area where construction of the fill-road took place. CASE HISTORY-BRIDGES AND CAUSE- WAYS IN COASTAL REGION 4 - SOUTH FLORIDA The State of Florida Department of Transportation (FDOT) in cooperation with the U.S. Department of Transpor- tation - Federal Highway Administration (FHA) contemplates replacing 37 of the 44 bridges along 87 mi (140 km) of the Overseas Highway (State Road 5, U.S.I) from Key West to Key Largo. The local- ized impacts due to construction and operation and regional impacts due to cumulative affects of the many bridges and associated causeways make an inter- esting case history study. Impacts dis- cussed in this case history study will be limited to terrestrial and aquatic im- pacts. Unless otherwise noted, the source of information is "Negative De- claration State Road 5 (U.S. 1) Bridge Replacements" (H.W. Lochner, Inc., Consulting Engineer 1975). Around the turn of the century, Henry N. Flagler, one of the founders of Standard Oil and builder of the Flor- ida East Coast Railroad from Jackson- ville to Miami, decided to extend his railroad to Key West. The resulting single track Overseas Railroad, complet- ed in 1912, covered a distance of 156 mi (251 km). In September 1935, a hurri- cane washed out the track and roadbed in the 30-mi (4£-km) stretch from Key Vaca to Plantation Key. It was decided that the railroad would not be rebuilt. Overseas Road and Toll Bridge Commission purchased the right-of-way and the associated physical assets and directed their efforts toward converting the remaining railroad structures to highway structures. The new highway was opened to Lower Matecumbe Key in 1936, to Big Pine Key in 1938, and to Key West in 1944. The bridge-causeway system supplies access between mainland and Keys for residents and vacationers. It carries an aqueduct which assures a supply of fresh water to the Keys. Many of the bridge structures have deteriorated severely since con- struction more than 30 yr ago. Between 1963 and 1973, a total of $10,000,000 was spent for bridge repair. This sum equals the original cost of the highway system. It is estimated that maintenance costs for the period from 1975 to 1985 will be $84,000,000. In 1974, Congress passed a highway bill which appropriat- ed $109,200,000 for the replacement pro- ject. In addition to the positive cost- benefit analyses between replacement and maintenance, there is definite con- cern that the deteriorating structures might experience structural failure, pos- sibly causing loss of life or serious in- jury. It would also result in loss of access between the Keys and the main- land, as well as possible health hazards in the Keys due to a loss of the potable water supply. The proposed reconstruction pro- ject will replace 37 of the 44 bridges 117 which represents approximately 17 mi (27 km) of the 18 mi (29 km) of bridges in the Overseas Highway. Of the 37 bridges proposed for replacement, 27 are the spandrel arch type, one consists of spandrel arch and pier sections, and the remaining 9 are composite pile type (Figure 49). The proposed bridge re- placement will also involve the recon- struction of approximately 21 mi(34 km) of bridge approach. About 11 to 33 acres (5 to 13 ha) of submerged land will be filled. The Florida Keys are composed of flat limestone formations with elevations ranging up to 15 ft (4.6 m ) above mean sea level. About 95% of the land is less than 5 ft (1.5 m) above mean sea level. Shoal water commonly ranges up to 0.5 mi (1.3 km) offshore. Shoals are gener- ally composed of the mangrove swamps, submerged turtle grass beds, and ex- posed limestone with little or no soil. The islands lie just north of the Tropic of Cancer, with Key West being the southermost city of the contiguous United States. Key West is closer to Cuba (90 mi or 145 km) than to Miami (154 mi or 248 km). Hurricanes, which occur frequently in the Florida Keys, are probably the most significant clima- tological feature of the area. The chain of 97 islands separates Florida Bay on the Gulf of Mexico side from Florida Straits on the Atlantic Ocean side. Relatively deep channels between the keys transport water be- tween the Gulf and Atlantic Ocean. It was estimated that the construction of the original railroad system reduced the cross-sectional water area between is- lands by more than 50% (Bailey 1977), which reduced water exchange between Florida and the Atlantic Ocean. Salini- ties in the upper portion of Florida Bay are greater than 50 ppt for 9 to 11 mo of the year, as compared to 34 to 37 ppt in the Atlantic Ocean (Davis 1977). There are no historical records, but reduced flow between Florida Bay and the Atlantic Ocean may be a factor con- tributing to the salinity difference (Bailey 1977). Florida Bay system is shallow as compared to the contiguous Atlantic Ocean and experiences diurnal temperature changes of 10° to 15°F (5.6° to 8.3°C) during part of the year (Davis 1977). This large diurnal tem- perature fluctuation does not occur in the ocean. The difference in solar energetics in the Bay as compared to the ocean is probably also a factor con- tributing to the salinity differences. The Florida Keys contain more endangered, threatened, and rare plant and animal species than any other re- gion of the State. Thirteen major parks and wildlife refuges lie partially or wholly within the Florida Keys. The extensive emergent mangrove forest and submerged turtle grass beds are vital habitat for the propagation of commercially and recreationally impor- tant species of fishes, shellfishes, and wildlife. Availability of habitat is the limiting factor for these populations. Protection of habitats is paramount to protection of plant and animal species. After a lengthy series of public hearings, advisory committee meetings with concerned residents and Federal, State, and local agencies, FD0T and FHA issued a "Negative Declaration State Road 5 (U.S. 1) Bridge Replace- ments" (H. W. Lockner, Inc., Consult- ing Engineer 1975). The negative declaration evaluated each bridge site separately, considering the following alternatives: Continue to maintain existing bridge; Remove existing bridge and construct new bridge on near existing alignment; Composite causeway struc ture- or C. D. ture; Construct new bridge on Gulf or Atlantic side of old bridge. Alternative A was easily eliminated based on economics and safety. Alter- native C was carried to the final eval- uation stage on nine bridges, but was eliminated based on possible adverse impact on natural and human environ- ments. Alternative B or D was chosen for each bridge on a site-specific basis. 118 The environmental impacts address- ed in the negative declaration were mostly localized in nature. They did, however, emphasize the role of habitat. Features of the project related to ter- restrial and aquatic ecological impacts that were addressed include o No unique vegetation will be re- moved. o Some submerged land will be filled. o Revegetation will be considered. o Net impact of filling kept at a min- imum by increasing bridge length and utilizing steep side slopes on approaches. o Control of turbidity due to con- struction will be studied. o Borrow from dry land will be pre- ferred as compared to borrow from submerged lands and from the pre- viously disturbed areas as compar- ed to new areas. o Offshore dredging for fill in vicin- ity of bridges not anticipated ex- cept where construction dredging may be required. o If submerged borrow operations were undertaken, containment of the "dredge plume" would be an important concern. o If dredging of marinas from the onshore areas is done, no connec- tion should be opened until turbid- ity has dropped to safe levels. o Holding borrow site depth to ap- proximately 20 to 25 ft will be con- sidered. o Width of the fill will be minimized by using steep slopes. o Structural retaining systems will be considered in some locations to reduce the area of bottom filled. Sheet pile walls or tie-back types will probably not be used due to potential washout. o Air quality standards will not be violated. o Where FHWA exterior noise criteria are expected to be exceeded, ex- ceptions will be requested. o It is improbable the runoff from bridge or road surfaces would vio- late State water quality standards. o The possibility of spillage of toxic materials from trucks will be re- duced because the road will be safer. o Construction and maintenance of new bridges will be according to State Standard Specifications for "Prevention, Control and Abate- ment of Erosion and Water Pollu- tion." o The use of sediment traps during construction will be considered. o Interim use of webbing, matting, mulching, and other mechanical means of erosion control will be provided for. o Consideration will be given to special specifications for bridge demolition and material disposal. o Consideration will be given to ap- propriate location of parking. o Where mangroves are impacted, their associated organisms can move elsewhere. o Retaining mangroves on the ocean side will be more important than on the Bay side because of their rela- tive scarcity and wave protection function on the ocean side. Many of the foregoing considera- tions can be considered as directed at localized impacts. After release of the negative declaration, FDOT negotiated with concerned natural resource agen- cies about regional considerations. Several agencies felt that FDOT was missing a good chance to return the circulation patterns between Florida Bay and the Atlantic Ocean to the pre- vious state that had existed before the Flagler railroad was constructed. As mentioned before, cross-sectional area between islands was reduced more than 50% by that project. All concerned individuals seem to agree that the salinity difference is real, but that the contribution of the causeway to this situation is not known. Natural physical differences between the two bodies of water are probably a sig- nificant causative factor. Channelization of the Everglades in 1962 alterations of fresh water Florida Bay is probably the salinity regime (Davis and resultant outflow to the also affecting 1977). There is definitely not agreement on whether increased flow between the 119 two water bodies would result in an overall benefit. Davis (1977) stated that there have been changes in the salinity of the estuarine areas of the Everglades frorr 0 to 12 ppt prior to 1940, up to 25 to 40 ppt presently. This has probably changed the nursery ground function of affected areas, but the nature of the changes is not know n. Numerous years of data show that the year-class strength of redfish in Florida Bay proper is positively corre- lated to high salinities in the spring, whereas the year-class strength of sea trout is positively correlated to low sa- linities in the spring. Alterations in springtime salinity might constitute a tradeoff between the population levels of these two fishes. Pink shrimp and spiny lobster pro- vide the two largest commercial catches in Florida. They are both highly de- pendent upon Florida Bay as a nursery. Recreational species, such as bonefish and tarpon, are also wery dependent upon Florida Eay as a nursery. The effect of salinity changes in the produc- tion of these important commercial and recreational organisms is not known (Davis 1977). It has been observed by Davis (1977) that the best coral reefs along the Florida Keys occur at the northern extremity where exchange of water with Florida Eay has always been minimal. John Pennecamp National Underwater Preserve is known worldwide and is lo- cated in this area. Coral is known to be very sensitive to altered salinities, temperature fluctuations, and turbidity and siltation. Waters flowing from Flor- ida Bay to the Atlantic Ocean through the Keys' channels are high in salinity, have large temperature fluctuations and are relatively turbid and silty due to wave action in shallow areas. If water circulation was increased between Flor- ida Bay and the Atlantic Ocean, there might be resultant impacts upon coral reef communities. The FDOT has agreed to conduct a two-phase study of the possible causes of a potential remedial action for the hypersalinity problem in Florida Bay. The first phase will include studies to determine the relative contribution tc the hypersalinity of the causeway area, natural physical processes, channeliza- tion of the Everglades, and other fac- tors. It will also determine the possible results of various measures to alleviate the problem. The second phase of the study will be to project the biological consequences of possible remedial actions, such as increasing the flow be- tween the Keys. Another major concern regarding the project is that valuable turtle grass beds will be directly and indirectly (sil- tation) affected by dredging. After several meetings it was agreed that FDCT would mitigate turtle grass losses acre for acre (Bailey 1977, Hall 1977). The FDOT has conducted a study to de- lineate the turtle grass beds as they presently exist. A comparable study after construction will define the acres of turtle grass that will be mitigated. Most of the shoals bordering the Keys contain flat limestone bottoms which do not have unconsolidated sedi- ments and are, therefore, not suitable for turtle grass growth. During an in- terview with F. Bingham of the Florida Department of Transporation, it was pointed out that some of the best turtle grass beds in the Keys are in the old borrow pits which resulted from the construction of the railroad and original causeway (Figure 55). The depth of the borrow pits fosters sedimentation of or- ganic material which serves as an excel- lent turtle grass substrate. It is not known, however, how long it takes for the turtle crass to establish itself in borrow pits" (Hall 1977). The depth of the borrow pit probably affects its suit- ability for turtle grass growth and the time period necessary for turtle grass establishment. The acre-for-acre mitiga- tion of turtle grass beds might possibly be accomplished by dredging a flat lime- stone bottom and allowing sedimentation and turtle grass establishment. Environmental concerns surround- ing the bridge replacement are many. Nearfield effects are somewhat classical 120 < O CD IS) S- >, ra CD ^ 3 o ) Li_ -Q 5- CD ia .c: CD 4-> c C TO •i — E CO o c ^ o <+- • r— -M 1 — H3 rO 3 ■r- +-> S_ •r— CD IS) 4-> fD CD E E o i — CO s o S- ■a cn CD +J to O CO 3 CO S- s_ +J en 00 f0 c a) o CO o S- >. QJ ra +-> 3 to CD O O'l M- 3 r0 C o CO O CO (O 4- QJ o s- S- U- i — o (V -Q c o CD •r- .C 4-> -4-> o CD £Z l/l •■- (/I C c/> O O ■t— S- +-> C_J CO +J c • cu LO E lt> ■r~ "O CD 0) S_ CO en ai 121 of construction projects in the coastal environment. The farfield effects, such as the potential contribution to hypersa- linity and associated ecological modifica- tions, are not as well known. It is probable that potential effects of cause- ways on the marine environment will be debated for many years. At present the key issue controlling the replace- ment project is the potential loss of life or serious injury that could result due to structural failure. dynamics in this coastal region. A hypothetical island is nearly "breached at one point, so a groin is built down- drift to cause accretion at the weak area. The construction of the groin approximately 50 ft (15 m) long by" 5 ft (1.5 m) wide causes little environmental damage because it is small. Turbidity, destruction of bottom habitat, and beach disturbance are minor when view- ed in light of the extent of nearby shoreline. CASE HISTORY - GROINS IN COASTAL REGION 5 - SOUTH ATLANTIC Coastal region from Cape Canaveral to Cape Hatteras is characterized by barrier islands, marshes, and estuaries (Virginia Institute of Marine Science 1976). The barrier beaches are long, narrow sand beaches separated from the shore by embayments of varying widths up to 30 mi (48 km). Most of the shore- line lacking barrier beaches is also sandy and flat and is broken by estuar- ies and tidal marshes. The sand is fine and is easily transported by the sea. The natural beach erosion resulting from the storms and tides has been ac- celerated by the often carelessly plan- ned placement of shoreline structures, such as groins, bulkheads, jetties, and breakwaters (Bruun and Manohar 1963). Some assumptions can be made about an undisturbed barrier island a mile or more in length and separated from adjacent islands by wide inlets. Natural processes will cause erosion and accretion of sand at various points; the storm winds and tides will break through islands, opening a channel into the lagoon while the other channels will close. The barrier islands will, over time, change in shape, size, and topo- graphy. The plants and animals found there will, as they always have, adapt to these changes. Unfortunately, man is often not tolerant of normal shoreline dynamics. Beaches must be stabilized to provide recreation, real estate, in- dustrial sites, or harbors. Insufficient data were available to provide a case history, so a hypotheti- cal situation was developed to demon- strate the effects of groins on shoreline There are effects which do not ap- pear immediately. The groin interrupts the littoral transport of sand, causing it to accumulate updrift. The beach updrift of the groin grows higher and extends out nearly the length of the structure. The updrift area is protected from erosion forces by a broad expanse of sand. This does little harm to the resident organisms because it is a slow accumulation process and not different from that to which they have adapted. The beach recedes downdrift since its normal supply of sand now lies updrift of the groin. If unchecked, it will re- cede until a breach occurs and the sea flows into the lagoon. The natural pro- cess has, therefore, been displaced in time and space. To protect the human investment, another groin is built and another until the barrier beach is en- tirely protected by a vast groin field. Each time a minor amount of damage is done to the environment, a few square feet of habitat is lost. However, in the mile of barrier beach, there could even- tually be as many as 50 groins. The amount of habitat lost becomes more significant. One little discussed effect of beach stabilization on barrier island systems is that of changing the physical and chem- ical characteristics of the estuaries and embayments lying behind the barrier islands. Periodic wave overwash or dune breaching allows seawater to reach behind the islands, causing salinity var- iations. Plants adapted to such an alter- ed environment survive, while others do not. When the beach is stabilized, suc- cession is toward plants not well adapt- ed to oceanic conditions (Bolan et al. 1973). The advantages or disadvantages of this situation depend on what is 122 desired as an end result for that coast- al area. The tradeoffs involved are dis- cussed by Dolan (1966) and Dolan et al. (1973). Altered salinity regimes in the embayment can also affect life cycles and productivity of various aquatic or- ganisms, although this has been little studied. CASE HISTORY - COASTAL REGION ATLANTIC BULKHEADS IN 6 - MIDDLE Within Coastal Region 6, a number of references are available on effects of bulkheads (Carstea et al. 1975a, Gantt 1975, Yasso and Hartman 1975, Chesa- peake Research Consortium 1974, 1976, Givens 1976). Most of the existing in- formation refers to Chesapeake Bay, but Yasso and Hartman (1975) discussed bulkheads in the New York Bight. The observations contained in the literature are broadly applicable within this re- gion, even though specific flora and fauna will vary from location to loca- tio n . Bulkheads in this region are used primarily to protect upland areas from erosion and to stabilize the existing shoreline. Construction of bulkheads with either steel or wood sheeting is common. Impacts in this region due to con- struction of a typical 150-ft (46- m) tim- ber bulkhead and the associated dredg- ing of 300 yd3 (274 m3 ) of fill were considered in a theoretical case history by Carstea et al. (1975a). In this case, it was expected that there would be no significant impact on water quality. The increased turbidity would not affect wa- ter quality significantly. There would be minor air quality and noise construc- tion impacts, and some organisms would be directly eliminated by dredging and burial. An alternative to the bulkhead con- struction is the use of a revetment. However, bulkheads provide mooring facilities which may be desirable in some situations. Once in place, bulkheads provide protection for upland areas immediately behind the bulkhead; however, unpro- tected areas adjacent to the bulkhead may be eroded, and this can undermine the bulkhead from the sides. Carstea et al. (1975a) claimed that bulkhead con- struction would have a positive effect on water quality by stabilizing the shoreline and reducing erosion. How- ever, Gantt (1975) stated that scouring may cause erosion at the toe of the bulkhead and that unprotected adjacent shorelines may erode because of the un- dissipated wave energy resulting from a bulkhead. Carstea et al. (1975a) con- ceded that the roughness coefficient will indeed decrease slightly with bulkheads yielding an increase in the velocity and the dispersion coefficient of the water, but stated that, if properly constructed and maintained, bulkheads will have no significant effects upon erosion, sedi- mentation, or deposition. On the other hand, one can expect alterations to lit- toral drift and currents, according to Gantt (1975). Carstea et al. (1975a) maintained that a small timber bulkhead would produce no significant increase or decrease in the storage capacity of the water body and no additional drift pro- blems. The differences in the conclu- sions of these authors are considerable, but may revolve around a different per- ception of what constitutes a "signifi- cant effect." Furthermore, a single small bulkhead, such as the one consid- ered by Carstea et al. (1975a), will have much less of an effect by itself than will many small bulkheads taken as a whole. Biological impacts of bulkheads are dependent primarily on the location of the bulkhead, with upland locations pro- viding the least damage. Construction below the mean high water line is more damaging, and construction below mean low water is most damaging. Filling be- hind a bulkhead will destroy organisms located there. Isolation of marsh grass- es from tidal waters will cause a loss of part of marsh grass community (Carstea et al. 1975a). Loss of wetlands will re- sult in the loss of detritus production, storage, and transfer of nutrients; loss of feeding, breeding and nursery areas for fish, shellfish, and the other organ- isms; loss of flow regulation and shore stabilization; and loss of habitat for the 123 waterfowl and terrestrial species. Gantt (1975) noted the destruction of fringe marsh and shoreline when dredging oc- curs, along with a reduction in species diversity in the zone near shoreline; nutrient cycle changes leading to lower water quality; high oyster mortality in the vicinity of the bulkhead; reduction in invertebrate production; and preven- tion of recolonization by scouring action in front of the bulkhead. Wolcott (1977) reported that bulkheads prevented the ghost crab (Ocypode quadrata) from reaching dune areas where they burrow during cold weather. A bulkhead provides docking facili- ties; however, it limits recreational ac- tivities associated with a natural coast- line (Carstea et al. 1975a). According to Carstea et al. (1975a), even a small bulkhead will cause erosion of sand and shallow water on neighboring beaches. Eliminating the littoral zone may reduce productivity in an area and thus affect fishing. They estimated that there was generally little or no socioeconomic im- pact of bulkhead construction in this region. From a biological standpoint, bulk- heads are generally not desirable struc- tures in this region. Reduction in the amount of marsh grass (Spartina alter- niflora, S. patens) will result in a tang- ible loss of the estuarine productivity. Carstea et al. (1975a) estimated that a 150- ft (46-m) timber bulkhead, assum- ing a width of 20 ft (6 m), would de- stroy 3,000 ft2 (914 m2 ) of habitat. This would result in a loss of 1,230 lb (558 kg) of detritus per year. This amount of detritus could support ap- proximately 9 lb (4 kg) of shellfish per year at 125 lb (57 kg) of shellfish sup- ported per acre per year (Carstea et al. 1975a, cited by Isard, W. 1972. Eco- logic-Economic Analysis for Regional De- velopment. The Free Press, New York, New York). It is possible to construct upland bulkheads which preserve wetlands and have a relatively minor effect on the coastal ecosystem. Each proposed bulk- head must be evaluated, based on its potential for damage, in light of com- munity existing at the proposed site. To afford maximum protection to the coastal ecosystem each bulkhead should be considered not as a single isolated structure, but rather as an addition to an ever-growing complex of shoreline structures. A possible alternative to bulkhead construction is the placement of riprap or other types of revetments, but these structures also have environmental con- sequences. If mooring facilities are de- sired, small piers may be substituted. CASE HISTORY - SANDBAG SILL BREAKWATERS IN COASTAL REGION 6 - MIDDLE ATLANTIC Sandbag sills are being tested un- der the auspices of the Virginia Insti- tute of Marine Science as alternatives to, or complements of, groins in the Chesapeak Bay (Greer 1976). No quan- titative biological studies were found and only a minimum of other information exists. However, since they are poten- tially a viable alternative to groins as shore protection devices, their use can be expected to increase. Chesapeake Bay has a long history of shoreline erosion, primarily resulting from wind-generated wave action. Slow- ly rising sea level also contributes to this problem. Greer (1976) reports that the 270 million cubic yards (249 million cubic meters) of material were eroded from Virginia's Chesapeake Bay shore- line between 1850 and 1950. Bulkheads, revetments, and groins have been used in an attempt to retard or stop this shoreline loss, but they are often un- successful (Greer 1976). In addition, navigation channels are clogged by eroded sediment and valuable real estate is being lost (Greer 1976, U.S. Army Engineer District, Norfolk 1977a). The constant and often severe erosion of the shoreline prevents permanent vegetation from becoming established. What already is present is eventually washed away as the shoreline recedes (U.S. Army Engi- neer District, Norfolk undated b). The result is a steady loss of shoreline wild- life habitat and constant turbidity caus- ed by soil being continually washed into the waterway. 124 Biological impacts of construction and existence of groins, bulkheads, re- vetments, and large breakwaters are discussed in those sections of this re- port. Data at hand afford no indication of the possible impacts of sandbag sill placement, but some inferences may be made as to type and degree of probable effects. Sandbags sills are long polyvinyl- chloride-coated nylon bags (Dura-bags) filled with sand. Their dimensions are 13 ft (4 m) long, 5 ft (1.5 m) wide, and 2 ft (0.6 m) high. They are plac- ed in the intertidal zone, usually less than 5G ft (15 m) channelward of the mean high waterline. When filled, each bag weighs 4 tons (3.6 metric tons), which is more than waves in the bay can move. Cost is reported as varying from $50 to $150 depending on whether professional help was obtained (Greer 1976). No data on the construction effects were found. Placing the sill breakwaters amounts to pumping them full of sand and locating them parallel to the erod- ing shoreline. The area directly beneath each bag would be lost as habitat and the source of sand cculd cause some de- pletion elsewhere. Without specific in- formation on construction methods, no further impacts can be predicted. Once placed, sandbag sills have shown themselves to be very effective in rebuilding beaches in the Chesapeake Bay. In one case a beach was doubled in width in three weeks (Greer 1976). How this local accretion affects adjacent beaches is not stated. The U.S. Army Engineer District, Norfolk (1977e, un- dated b), predicts no adverse effects due to flood height and drift, reduction of erosion, or accretion on beaches. They also expect no adverse effects on water quality, water supply, or aesthet- ics. Warning signs are recommended to prevent boaters from hitting the sills, which are submerged at least during high tide. Prevention of the shoreline erosion should have beneficial effects on the biological resources of the area. Upland vegetation loss would be reduced and, thus, loss of wildlife habitat would be slowed (U.S. Army Engineer District, Norfolk undated b). The effects on in- tertidal biota would depend, in part, on the amount of sand deposited, and how rapidly deposition occurred. Since ero- sion and accretion are natural process- es, many intertidal organisms can adapt to changing bottom levels. Fish should be little affected except that reduced turbidity might prove beneficial. With no action, erosion might continue. The dredging for beach nourishment is a biologically more harmful alternative, as well as being costly. Additional information is being de- veloped from ongoing studies at Virginia Institute of Marine Science concerning sandbag sills in Chesapeake Bay. CASE HISTORY - PIERS, PILINGS, AND OTHER SUPPORT STRUCTURES IN COASTAL REGION 7 - NORTH ATLANTIC The literature contains very little information on piers and pilings in the Coastal Region 7. Carstea et al. (1975a) present a theoretical case study of a 200-ft (61-m) timber pier in the north- eastern United States. A developers' handbook which contains some informa- tion on this topic for Connecticut is presented by Carroll (undated). The construction of a timber pile pier is usually of short duration. For example, Carstea et al. (1975a) estimate construction time of a 50-ft (15-m) long pier at 2 to 4 days, using trucks for 3 hr, a piledriver for 1 hr, and a crane for 10 hr. A slight increase in water turbidity and sedimentation may result. Increased noise and air pollution levels are usually not excessive. This region is characterized by numerous types of environments (Vir- ginia Institute of Marine Science 1976). Consequently, impacts on the environ- ment due to a specific type of structure will vary from place to place. Effects of a pier on areas such as wetlands, tidal flats, grassbeds, breeding nurseries, wintering and feeding areas, and migra- tion pathways are the most significant (Carstea et al. 1975a). Productivity 125 will be decreased in the area under the pier. This can include vegetation, algal, and shellfish productivity. Grass- beds will also be affected by resultant boat traffic as will the fish activities. Carstea et al. (1975a) recommends that grass beds and other areas of signifi- cant natural resource productivity be avoided as sites for pier construction. Wooden structures in this area should be properly treated against ma- rine wood borer attack, although the problem of attack against treated wood piles should not be as extensive as in some of the warmer coastal waters to the south. The gribble (Limnoria tri- punctata), considered to be the species causing the greatest threat to creosote and coal tar treated piles, only breeds where the temperatures are above 57°F (14°C) and is, therefore, not prevalent in Coastal Region 7 (Lindgren 1974). A single residential pier is not likely to have an extensive impact on recreation in the general area. How- ever, several piers in the area may re- strict recreational activities and shore- line access. Pier size and number like- wise affect socioeconomics of the area. Piers used in connection with a launch- ing ramp or marina may cause increased usage of the area and affect property values or ecological relationships. The possible alternatives to a tim- ber pier used for moorage in this area would include solid-fill piers, anchor buoys, single piles, dolphins, placement of boats in local marinas, or land stor- age. The use of anchor buoys or piles would cause less adverse impact to the environment. The use of a solid -fill pier would, in most cases, be an unsat- isfactory alternative due to the influ- ence it would have on water movement and sediment transport. A single, properly designed and constructed open-pile pier would cause relatively little adverse impact to local biota. Host of the impact would be as a result of related activities, such as dredging or increased usage of the area. CASE HISTORY - JETTIES IN COASTAL REGION 7 - NORTH ATLANTIC Except for Long Island, little in- formation on jetties in the New England area was found. The amount of biologi- cal data was minimal and was generally applicable to most of the United States coastline (Carstea et al. 1975a). Fire Island Inlet on Long Island has a documented history extending back to 1825. Fire Island is a long bar- rier beach lying off the south shore to Long Island. It is broken by a number of inlets, many of which have been sta- bilized by jetties. The Fire Island Inlet is unusual in that two sections of the barrier beach, Fire Island and Oak Beach, overlap and the inlet curves be- tween them. An irregular channel is maintained by strong tidal currents in the inlet, but throughout its recorded history the channel has maintained its S-shape. Over the years both erosion and accretion has occurred so that Fire Island has grown toward the west and Oak Beach has been cut back (Shepard and Wanless 1971). A jetty was completed at Democrat Point in 1941. This temporarily stopped the westward advance of Fire Island. The outer beach soon filled behind the jetty on the south side of the island. Following this, sand was deposited land- ward of the north side and caused a bar to develop. The bar eventually reached nearly across the inlet to Oak Beach. As the channel narrowed, the strength of the tidal currents increas- ed, and severe erosion occurred on Oak Beach. The beach was artificially nour- ished and a new channel cut, but the latter soon filled. A second jetty was built and erosion has apparently stop- ped; however, an adequate channel does not exist through the inlet (Shepard and Wanless 1971). Jetties, as with other shoreline structures which interrupt littoral drift, upset the natural beach processes and cause unwanted and sometimes unfore- seen erosion and accretion (Davis et al. 1973). This is well illustrated by the changes in Fire Island Inlet. Not shown were the effects of these changes on the plants and animals of the area. No information was given on habitat loss or alteration. It can be assumed that the construction and existence of the jetties 126 caused impacts on the biological envi- ronment. Among the effects of jetty construction at Fire Island Inlet, the following are easily predicted: turbid- ity, destruction of benthic organisms, reduction of species diversity and food supply, release of toxic sediments, and creation of new substrate (Carstea et al. 1975a). The validity of these pre- dictions could be questioned, however. Additional study would be required to discover site specific impacts. Jetties are designed to stabilize inlets and, according to Kieslich and Mason (1975), two objectives must be considered. These are minimizing un- desirable effects of wave action on nav- igation channels and eliminating artifi- cial maintenance of the channels. These objectives do not, in any way, consider biological impacts of the jetties. In fact, no source of information was encounter- ed which dealt with the physical or bio- logical impacts of jetties. CASE HISTORY - BULKHEADS AND ASSOCIATED DREDGING IN COASTAL REGION 8 - GREAT LAKES In the Great Lakes region (Coastal Region 8) there are a number of refer- ences dealing with bulkheads, but very few dealing with associated environmen- tal impacts. Boberschmidt et al. (1976) discussed environmental impact of small structures in the Chicago District of the U.S. Army Corps of Engineers. They provided an analysis of a hypo- thetical 200-ft (61-m) bulkhead on the Fox River in Wisconsin which involved no dredging. They also considered main- tenance dredging at a commercial dock on the Illinois River. Morton (1976) has provided a comprehensive review of the ecological effects of dredging. The U.S. Army Corps of Engineers (undat- ed)gives an excellent layman's introduc- tion to shoreline protection structures for the Great Lakes. Because of a lack of specific information, only generaliza- tions about the effects of bulkheads in the Great Lakes are contained in this case history study. Bulkheads are constructed in the Coastal Region 8 to retain, or prevent the sliding of, land and secondarily to protect the upland against wave dam- age. Bulkheads also provide moorinq facilities in many areas. Many unsatis- factory methods of shoreline protection may be employed prior to installation of an adequate structure such as a bulk- head (U.S. Army Corps of Engineers undated) . Many possible construction alterna- tives exist. They vary substantially in cost. A wire mesh, woodpile, or sand- bag bulkhead may cost no more than $15 per linear foot (0.3 m), while a steel bulkhead may cost as much as $330 per linear foot (0.3 m) (U.S. Army Corps of Engineers undated). Among the construction alternatives which may be considered in addition to many types of bulkheads are revet- ments, breakwaters, and groins. Construction impacts of bulkheads are similar to those in other areas of the country, including increased turbid- ity and noise, reduced air quality, and smothering of some organisms in the backfill area. Resuspension of bottom sediments will be greater when dredging is associated with bulkhead construc- tion. The use of diked disposal for hydraulic dredge spoils results in sig- nificantly less turbidity than many other methods of disposal (Morton 1976). Bulkheads and seawalls are often successful in providing immediate pro- tection for areas in which no further bluff recession can be tolerated, but they frequently fail because of toe ero- sion and back pressure (Michigan Sea Grant Advisory Program undated). For- ney and Lynde (1951) document a his- tory of attempts to protect the P res que Isle peninsula from erosion. The effects of bulkheads on coastal processes are similar to those found in other coastal regions. Erosion in adja- cent areas which are not bulkheaded or otherwise protected can sometimes be expected. Littoral transport may also be affected. A lack of dissipation of wave energy can be expected on the lakeshore during storms as compared to the unbulkheaded beach (Boberschmidt et al. 1976). 127 Biological impacts resulting from the presence of a bulkhead include some reduction in littoral zone productivity. Foreshore habitat is likely to be elimi- nated by construction of a bulkhead. In rivers,bulkhead construction reduces cover along the banks ( Bobersch midt et al. 1976). Dredging may cause increases in suspended solids, reduction in dis- solved oxygen and increased concentra- tion of hydrogen sulfide, and release of pollutants which may be trapped in the sediments (Morton 1976). These factors can be detrimental to fish and other or- ganisms in the vicinity of the dredging operation. Bulkheading may protect certain areas from erosion, at least temporarily. Bulkheads may also provide mooring fac- ilities. However, recreational activities requiring unaltered habitat will be re- stricted by bulkhead construction. Because bulkheads may result in an increased energy environment and erosion of adjacent beach areas, riprap revetments may be preferred as an al- ternative. If the bulkhead is needed, riprap revetment may be placed in front of the bulkhead to reduce scour and biological damages. Exchange of subsur- face water is facilitated through riprap; wave energy is somewhat reduced be- cause of its increased roughness. Both revetments and bulkheads may limit ac- cess to beaches. Groins and breakwa- ters can also be considered as alterna- tives to preserve a beach by altering shoreline processes. CASE HISTORY - GROINS IN COASTAL REGION 8 - GREAT LAKES The Michigan Demonstration Ero- sion Control Program is involved in an ongoing research program to test the effectiveness of various shore protection devices. The physical environment at each test site is known; but, unfortu- nately, no information is collected con- cerning the biological environment. The other sources of information concerned with groins in the Great Lakes do not include biological impact data either. Biological effects must be inferred from general information. Four Mile Park on the Lake Huron shore in Sanilac County, Michigan, was chosen as a test site for the six groin types (Table 3). The bottom is clay derived from the high clay bluffs along the shore. Erosion has long been a problem and homes have been destroyed as the bluffs eroded (Brater et al. 1974). All six groins have had some success in trapping sand at the base of the bluffs (Figures 56 to 59); however, the bluff is continuing to recede (Brat- er et al. 1977). No information on construction im- pacts was given. However, they can be assumed to vary from mild turbidity and beach disturbance for the sandbags to somewhat more turbidity and beach dis- turbance plus air and water pollution for rock mastic structure. These were constructed by pushing the rocks pre- viously dumped on the beach into place with bladed tractors and pouring hot asphalt mastic over them (Brater et al. 1974). The effects of construction activ- ities on the biota is not known. Since the shoreline was actively eroding, with little or no beach, any organisms pres- ent should be adapted to a disturbed environment. The success of the groins in trap- ping sand resulted in a change from a clay to a sand substrate. This may have resulted in a change in species composition of bottom dwelling organ- isms. 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CD C Q i e O >, c/i CD CD S- -M 3 S_ CD 3 •i- O 130 CO 4- rC O z: 00 i+- on o O ^~ +-> c en d) C E • i — +J 3 S- O fO -C Q. 00 (D Q #i OJ C +-> f0 • 1 — CD 00 •r— .c (J o rd i — £ *rm C i»- rcl o CO >1 +J CO re 0) +-> C S- •i — 3 O o S- o Dl >> oix: (O Q. .□ (O T3 i- C Oo rd o CO +-> o .c • D_ r~^ lo TJ C O o Q. (O i- o CD +-> c o S- DC en c ro O J- ■I- 3 .o -t-> re re • o 00 4-- ^ C CD e CD +-> s- s- Ol Q. •i- CD 132 It- CD cu +-> S- o o <0 S- cn o 4-> o a> +j •f— oo u ro • i — t/i •i — c O 03 S- OO 3 o +J fO 00 M- fO O E +-> -^ c <_> O) o E a: +-> S- (O • Q. CT> CO LD O c "3 0) cn s- •r- 13 -C CD O 133 RESEARCH IN PROGRESS Seven research projects investigat- ing the design of and/or biology associ- ated with shoreline structures are cur- rently underway. Generally these pro- jects can be placed in three categories: o Those looking for low-cost shore- line protection measures for use by the property owner; o State of the art reviews of the structure type and/or its effect on the environment; o Research about the effects of a structure type on either the bio- logical or physical environment. Projects investigating various low- cost protection measures, such as the Michigan Demonstration Erosion Control Program, often include construction of a structure as well as identification of the problems. The other two types of re- search usually concentrate on effects of existing shoreline structures. The Michigan Demonstration Ero- sion Control Program, initially funded by the Michigan Department of Natural Resources, began in 1973. Since that time, it has received funding from the several other organizations, including the Michigan Sea Grant Program. The objective of this program was to find low-cost methods of protecting Michi- gan's shoreline which a property owner could help construct. Low cost was de- fined as under $100 (preferably less than $50) per square foot of protection. Nineteen shore protection demonstration installations have been constructed. These include revetments, breakwaters, bulkheads, and groins. Laboratory in- vestigations and historical studies of erosion conditions are also being con- structed. It is hoped that by 1978 enough information will be available to evaluate the effectiveness of each in- stallation. A detailed engineering-eco- nomic evaluation of the structures will be made. Reports are published each year discussing data collected during the previous year. Greer (1976) reported that Robert Byrne and Gary Anderson of Viroinia Institute of Marine Science are working with sills to stop erosion in Chesapeake Bay. The sills are installed offshore in shallow water. They have used the poly- vinylchloride-coated nylon Dura-bags filled with sand to construct sills to cause nearshore accretion. The cost for each sill was approximately $12.50 per linear foot (0.3 meter) installed. Pre- liminary results indicate this method of erosion control is very effective in parts of Chesapeake Bay. Dr. Paul Shuldiner of the Univer- sity of Massachusetts at Amherst is heading an investigation of the impact of highways on wetlands. This study is being conducted for the National Co- operative Highway Research Council. The expected products will be an an- notated bibliography, a state of the art review, and six case studies. It began in mid-1977 and was expected to be completed by mid-1978. William Brisby of Moorpark College (Moorpark, California) reports that a consulting firm is doing a study on the biota of Rincon Island, California, for the U.S. Army Corps of Engineers. Rincon Island is man-made, located ap- proximately 0.5 mi (0.8 km) offshore. A causeway runs to the island from shore. J.M. Kieslich and C. Mason (1976) of the U.S. Army Corps of Engineers are working on the channel entrance response to jetty construction. In their 1975 paper, they generally concluded that wave processes contribute more to channel migration near a jetty than hy- draulic processes do. Additional work is being performed by them to quantify the controlling wave and hydraulic pro- cesses. Their results will be presented in a future report. Two studies are underway at the University of Rhode Island at Narragan- sett. Neil Ross and Gail Chmurg are conducting a state of the art review of the biological impacts of small boat har- bors. Daniel 0'Neil is investigating the fouling communities on the floating tire 134 breakwaters for the Marine Advisory Service. The objectives of 0' Neil's study are to identify and quantify fouling communities, determine rates of growth, look for the biological mechan- isms of controlling fouling communities, and study water circulation in small harbors. The study was to be completed by Fall 1977. Some articles contained in the lit- erature make reference to studies which were planned or underway at the time of publication of those articles. Refer- ences published prior to 1975 which in- dicated that research was planned or underway included Researcher Structures to be Studied Georgia Depart ment of Natural Resources 1974 groin Marks and Clinton 1974 revetments, breakwaters, bulkheads, and groins Machemehl and Abad 1973 g roi n Stone et al. 1973 reef Berg and Watts 1971 groin Riese 1971 groin Cronin et al. 1969 dredge-fill, jetty, groin Colley 1967 pilings Slaughter 1967 bulkhead Saville et al. 1965 revetment Lee 1964 harbors Scott 1964 jetty Nagai 1961 breakwater Brater 1954 bulkhead, revetment, groin Researcher Cole undated Structures to be Studied breakwater, harbor The only results of these proposed studies which were uncovered during the present study are contained in the articles by Brater et al. (1974, 1975, 1977). These studies were alluded to in the Marks and Clinton (1974) article. It is presumed that there are many relevant studies underway that are not noted in the literature or that were not determined during interviews or in re- sponses to questionnaires. In addition, there are most likely numerous studies underway that deal with strictly engi- neering aspects of shoreline structures. The best sources of information regard- ing ongoing studies are probably the U.S. Army Engineer Coastal Engineer- ing Research Center in Fort Belvoir, Virginia, and the U.S. Army Engineer Waterways Experiment Station in Vicks- burg, Mississippi. A large number of studies which are somewhat peripheral to the present study are also presently underway. Ex- amples would be the numerous biological studies on artificial reefs and dredging effects and engineering studies on mate- rials, life expectancy, and structure design. ENVIRONMENTAL METHODOLOGY IMPACT ASSESSMENT The majority of studies assessing the environmental impact of minor shore- line structures on the coastal environ- ment have been nonexperimental. Over 75% of the information sources reviewed were literature reviews, guidelines, and nonexperimental environmental impact assessments and statements. Systematic research studies con- ducted before and after the structure installation were rare, and those con- ducted were almost exclusively concern- ed with physical effects or engineering considerations. One ongoing research program that falls into this category is Michigan Demonstration Erosion Control 135 Program (Brater et al. 1974, 1975, 1977; Marks and Clinton 1974). This study is limited primarily to physical effective- ness of low cost groins and revetments. In another study, historical records were compared with the existing condi- tions to discover changes in littoral drift and the beach erosion after a jetty was constructed (Dantin et al. 1974). One series of biological studies was con- ducted both prior to and after installa- tion of various parts of a marina in southern California (e.g., Reish 1961, 1962, 1963). Another research method involves systematic studies conducted after the installation of structures. These studies primarily described the physical condi- tions in the presence of a structure. For instance, Diskin et al. (1970) de- scribed piling up of water behind low and submerged breakwaters, and Nagai (1961) discussed the absorption of wave energy by concrete facing components. An exception to this generalization has been a number of biological studies which have compared the existing bulk- headed areas to adjacent natural shore- lines. Examples of this method of study are found in Corliss and Trent (1971), Ellifrit et al. (1972), Heiser and Finn (1970), Millikan et al. (1974), Mock (1966), Moore and Trent (1971), Trent et al. (1976), and White (1975). 136 EVALUATION OF EXISTING DATA INFORMATION OBTAINED 555 references were obtained that were considered potentially applicable to the objectives of the study. Numerous additional articles were uncovered, but not obtained because they were not ap- plicable. The 555 articles were consid- ered as potentially applicable, based on their title or on recommendations con- tained in the questionnaires or acquired during interviews. These articles were read and abstracted, and data sheets prepared where appropriate. An article was assigned a rating only if it was di- rectly applicable to the present study. About 405 of the articles that were read were considered directly applicable. The remaining 150 articles contained in- formation that was related, but not di- rectly applicable to the study. Figure 60 contains histograms of the number of references obtained by structure, category, and rating. It is emphasized that the rating was for use- fulness to the present study and not scientific excellence or validity. Infor- mation of questionable validity is of questionable usefulness, but information of high veracity may also be of limited usefulness. Buoys and floating platforms Piers, pilings, and other sup- port structures Based on this classification and the histograms in Figure 60, bridges and causeways, and the small boat harbors would appear to have received a small amount of study in light of their poten- tial impacts. It should be noted, how- ever, that the data base contains much information that is not impact assess- ment oriented, but directed at engineer- ing constraints. Figure 61 contains the number of references obtained by structure type and coastal region. The general cate- gory is for articles that were not spec- ific for one coastal region. Much of the acquired information was not region specific. In many cases the histograms reflect structure prevalence and history of associated difficulties within that re- gion. Examples would be jetties in the North Pacific (Coastal Region 1) and bridges and causeways in South Florida (Coastal Region 4). This is not always the case, however, as is exemplified by the small boat harbors in South Florida (Coastal Region 4). The consensus of personnel who worked on this study was that struc- tures could be classified as having the high, moderate, or low potential for environmental impact as follows: High impact potential Small boat harbors Bridges and causeways B ulk heads Breakwaters Jetties Moderate impact potential Revetments G roins Ramps Low impact potential 137 t«--< — s "i*iiifmrt-iT»WWt T t 1 i r saaua-ia^ay j.o jaquinKi t c/> E s_ en o c >*- •i- +-> ro r— o o. 1- >> o c o •I — -<-> CO '- • i- ^— O 3 4- 4- IZ QJ ■i — (/> =; -n QJ -(-> C ■r— o C O) o S- o 01 3 (O +-> en •r- O) 10 O ^ *i — 4-J TJ s_ C f0 rD CU >> JC !- 4-> O cn -a ai OJ +j 4-J ra ro o o '1 — O i/l CT> >^ C XJ •j— +-> V) ID a) S- o c ^ OJ -a s_ 3 +-> 4- i/> O 4-> s_ C 01 CU -Q (/I F a) 3 s_ C CL o • 4-> o C s- > =3 a> CD i — •r- aj 138 o to 01 2 S- saouajaj,ay jo jaqoinfj 139 0 ■ (— 0 +J • 1— ro 4- F •i— i- O O o> 4- Q. C CO •1 — 4-> "O O CD C c •1 — CD fO S- +J QJ c s 0 0 ■l-> ro o c CD 1- CD S- QJ +-> S- CO s_ -o o CO O ■r- >> CT> J- oi o S_ en CD I— +J ro ro 4-> (J to ro 1— o ro o s- >> c .a OJ to CD OJ O -C C I— OJ s- 0J • <*- >> oj -a +-> 4- to S- c 01 CD -Q (/] >, E CD -»-> 3 c. +J C Q. CD -3 CD CD CO +J c oj ro t- > 3 CD Dlr- •r- CD u. s_ GENERAL COMMENTS ON THE DATA BASE After evaluation of the existing data base, several generalizations can be made as constructive criticism. Much of the available information was developed for a specific project as support for an environmental impact assessment. Some of this information is biased in one direction or the other. A large amount of the information on the effects of shoreline structures is engineering-oriented. There is also a large body of literature concerning the distribution and tolerance limits of biota of the coastal zone. Very little informa- tion exists on the impact of structures upon the biota. As a result, most envi- ronmental impact assessments rely on the ability of individuals to extrapolate impacts from what they know of the con- struction procedures, coastal physical processes, and nonstructure related bio- logical data. Most of these assessments are made in a climate of potential litiga- tion. The result is an extremely water- ed-down product that is only marginally based on fact. The literature on bio- logical impacts of the minor shoreline structures is characterized by these types of assessments. An evaluation of the potential im- pact of some minor shoreline structures by a competent biologist often would re- sult in a negligible impact conclusion. Unfortunately, the present regulatory climate necessitates a lengthy discussion of potential impacts. In order to pre- pare such a discussion, seemingly in- consequential matters are discussed at such length that everyone starts believ- ing they are truly problems. Lengthy discourses of turbidity and sedimenta- tion effects of rocks landing on a sand bottom fill the impact assessment litera- ture. It is doubtful that competent biol- ogists would project a probable impact due to fish gills being clogged, fish dy- ing from released toxic materials, ben- thic organisms being smothered, and primary productivity "being reduced sim- ply by the placement of stone in inter- tidal habitats. However, these state- ments are rampant throughout the liter- ature, with the sideline comment that these impacts are probably minor. This syndrome seems to be more prevalent for structures with low potential impact. The opposite syndrome is also evidenced in the literature. An example would be concluding no potential impact based on a nonexistent data base. Much of the literature is negative in nature. There are many examples where structures have had an overall positive impact on an area. Attraction of fishes to structures is often inter- preted as being a beneficial impact. Both positive and negative aspects should be evaluated. Much of the literature evaluates a structure as if it were in a vacuum. The impact of a single groin will often be negligible, but that single groin may cause a stepwise series of groins to be built, each of which is to mitigate the effects of the previous groin. The socioimpacts caused by bulkheads and the resultant house, or ramps and the associated boating pressure are other examples. Factors such as these should be considered when evaluating the im- pact of structures. 140 RESEARCH NEEDS A detailed review of the literature results in the conclusion that the data base available for projecting biological impacts of minor shoreline structures is extremely sparse. The research needs are virtually unlimited for each type of structure and for each coastal region. It would be unreasonable to propose a study on each structure type within each coastal region that was designed to determine the magnitude of each con- ceivable type of impact. We have, there- fore, proposed avenues of approach that will result in timely and cost-effec- tive answers to the questions most fre- quently asked. Data used in determining biological impacts of the shoreline structures are usually drawn from three data bases. The most applicable data base is the one containing information on the chem- ical, biological, cr physical impact of a specific type of structure. Examples would be articles on chemical releases from resuspended sediments during the jetty construction, fish attraction to breakwaters, and changes in beach pro- file due to groins. As is evident in the text of this report, this type of infor- mation is scarce. The second data base contains in- formation on engineering considerations in structure design. Examples would be methodologies for calculating wave impact, structural integrity, or changes in littoral transport. This information is often useful in determining biological impact, but is not directly applicable. The third data base contains infor- mation on biological phenomena that is not related to a specific type of struc- ture. Examples of this type of informa- tion are the attraction of the fishes to artificial reefs and other submerged structures; dredging effects upon ben- thos; and succession, diversity, pro- ductivity, and biomass of the commun- ities that foul submerged structures. This information is useful if it can be applied tc a specific type of structure. During the present study, infor- mation was entered into the data base only when it was specific for a particu- lar type of structure and a physical, chemical, or biological environmental im- pact. Information from the other two data bases was not entered into the system. During the present study, de- scriptions of certain impacts recurred through the literature. Examples of the more significant recurrent impacts are Changes shoreline dynamics Affects littoral transport Changes wave energy Changes sediment composition Increases turbidity Causes suspension of toxic chemicals Changes dissolved oxygen, salinity, or temperature Shades the water Affects circulation Alters existing habitat or creates new habitat Alters species composition Affects migration patterns Socioeconomic changes due to increased area usage A study should be performed to analyze each of the recurrent types of impacts based on each of the three data bases. For example, the effects of in- creased turbidity due to any of the structures would be a valuable study. An impact approach in addition to a structural approach would result in a considerable refinement of the conclu- sions reached in this report. Review of available literature un- covered certain major gaps in the data base. The following recommended stud- ies would help to fill in some of these areas where information is lacking. o How are biological communities af- fected by structures which stabi- lize shorelines? o How do changes in wave energy patterns affect biological commun- ities? For example, what are the differences in communities in front of and behind breakwaters? 141 What are the positive and negative effects of chancing the type of habitat that occurs in the area (e.g., rock vs sand)? Does construction-generated tur- bidity clog fishes' gills or zoo- plankton/filtration mechanisms. Do avoidance mechanisms operate to prevent this? Can loss of phytoplankton or mac- rophyte primary productivity due to structure shading constitute a threat to an ecosystem? Can loss of phytoplankton or mac- rophyte primary productivity due to construction turbidity constitute a threat to an ecosystem? What are the effects of structures that protrude into the water or channelize current upon the migra- tion of fishes, mammals, and crus- taceans? How do solid structures affect sys- tems through alteration of circula- tion? What are the biological effects of structures such as rubble mound groins or riprap revetments in areas where this type of habitat did not formerly exist? Under natural conditions, is avail- able habitat one of the most impor- tant factors controlling the produc- tivity of a specific organism? What are the effects wave energy patterns ment composition and biological productivity? of altered upon sedi- associated What are the zones of influence of wave energy altering structures? For example, how far away from a bulkhead are the energy altera- tions felt? Bottom profile and sediment composition alterations are included in this concern. What are the effects of various types of submerged surfaces on productivity? For example, does a riprap revetment offer a better habitat than a bulkhead or con- crete revetment? What are the cumulative effects of many of the same type of struc- ture in an area or a combination of many types of structures in an area? Studies similar to those on bulkheadinc in Texas (Coastal Re- gion 3) are needed in the other coastal regions and about other types of structures. What are the structures on wildlife? effects of shoreline waterfowl and other 142 Answers to all the above questions could be generated through field or lab- oratory studies. There are certain ques- tions, however, that could best be an- swered through a literature review which incorporates all three of the aforementioned data bases. The results of the literature review could answer the questions or could serve as a firm basis on which to design the required field or laboratory studies. The case history studies for each coastal region were selected based on the recommendations of local U.S. Fish and Wildlife Service personnel. Their recommendations were based on the most troublesome structures they encounter when reviewing Corps of Engineers' permit applications. In several cases, there was not enough information avail- able to write a case history, and theo- retical case histories were constructed. In other instances, the data base was so poor that the majority of the case histories was theoretical. Circumstances where theoretical information was used would seem to be appropriate topics for detailed study. These topics were Southern California Coastal Region 2 Bulkheads South Atlantic Coastal Region 5 Groins South Atlantic Coastal Region 5 E ulkheads North Atlantic Coastal Region Piers, piling, structures and other support North Atlantic Coastal Region 7 Jetties Great Lakes Coastal Region 8 Bulkheads and associated dredging Great Lakes Coastal Region 8 Groins (biological) It was the consensus of project personnel that small boat harbors had a high potential for environmental impact. Small boat harbors can contain all of the other structures mentioned in this report. Harbors would, therefore, make good case studies within each region of the United States. The effects of num- erous structures could be studied at one location and within the budgetary constraints of one study. Sites will have to be carefully chosen, however, to assure that the effects of one struc- ture type are not overpowering the ef- fects of another or that secondary ef- fects, such as petrochemical pollution, are not of far greater significance than the strictly structural effects. Project personnel also considered bridges and causeways to have a high potential for environmental impact. Un- like many other structures, their effect can extend over an area much larger than the immediate vicinity where they are constructed. Such regional impacts are discussed in the case history stud- ies on bridges and causeways in Florida (Coastal Regions 3 and 4). Detailed studies on the effects of bridges and causeways would help to determine if fears, arising largely from conjecture, are factually based. It would be very helpful if several locations could be studied both before and after construc- tion. The effects on tidal circulation, biological productivity, and flood con- trol should be prime concerns of the study. In summary, there are numerous studies that would enhance the state of the art relative to the prediction of the biological impacts of minor shoreline structures on the coastal environment. One avenue of approach that will result in timely and cost-effective answers to many structure-related questions is the integration of the purely biological, purely engineering, and structure im- pact related data bases currently in existence. In addition to this approach, there are several field studies which, if undertaken, would contribute substan- tially to the presently available data base. 143 GLOSSARY1 Aerobic Life processes occurring only in the presence of free oxygen. Anaerobic Life processes occurring without the presence of free oxygen. Anadromous Fish that reproduce in fresh water, but spend a portion of their life in salt water. Backfill Material used to fill behind a smal 1 structure such as a seawall or bulkhead, Backshore Zone of beach lying between foreshore and coastline acted upon by waves only during severe storms. Barrier beach (also barrier island) Bar essentially parallel to shore, with crest above normal high water. Bay Recess in shore or inlet between two capes or headlands; larger than cove, smaller than gulf. Bay mouth bar Bar across the mouth of an embayment. Benthos Organisms growing on or associated principally with the water bottom. Berm Nearly horizontal part of beach or backshore formed of material deposited by wave action. Biota Animal and plant life of a region. Biotic Environmental factors which are the result of living organisms and their activities. Bluff High steep bank or cliff. Boat basin Naturally or artifically enclosed or nearly enclosed harbor area for small craft; see harbor. Portions of this glossary have been estracted or adapted from Allen (1972) and Hurme (1974) 144 Boulder Rounded rock more than 10 in (25.4 cm) diameter; larger than cobblestone. Breaker zone Zone of shoreline where waves break. Breakwater Structure protecting shore area, harbor, anchorage, or basin from waves; see jetty. Bridge Structure erected to span natural or artificial obstacles such as rivers, highways, or railroads and supporting a footpath or roadway for pedestrian, highway, or railroad traffic. A bridge would normally consist of structural members made of steel, concrete, or wood. Bridge abutment Structure supporting the bridge at the point where the land meets the water as distinguished from a pier which is wholly in the water. Bridge pier Structure in the water which supports a bridge. Bulkhead Structure or partition built to prevent sliding of the land behind it. It is normally vertical or consists of a series of vertical sections stepped back from the water. A bulkhead is ordinarily built parallel or nearly parallel to the shoreline. Buoy A floating object moored to the bottom of a waterway, used for marking, moorage, etc. Caisson A watertight structure used for construction work in water. Calcareous Consisting of or containing calcium carbonate. Canal Artificial watercourse cut through land area. Cape Relatively extensive land area jutting seaward from continent or large island which prominently marks change or interruption of coastal trend. Causeway A way of access, or raised road, typically across marshland or water. A causeway would normally consist of an embankment constructed of earth, sand or rock dredged or dumped in place. Cliff High steep face of rock. 145 Climax Final and most stable of series of communities in succession, remaining relatively unchanged as long as climatic and physiographic factors remain constant. Cobble Naturally rounded reck, 3 to 10 i n diameter. Cofferdam A temporary watertight structure built in the water and pumped dry for construction of piers, bridges, dams, etc. Community Association of plants and/or animals in given area or region in which various species are more or less dependent upon each other. Coquina A soft porous limestone with high shell and coral content. Cove Small, sheltered recess in coast, often inside larger embayment. Cumulative effects Effects which result from an accumulation of a number of structures in a coastal area. Current , long shore Littoral current in the breaker zone moving parallel to the shore. De adman A wooden pile, concrete Mock or horizontal timber placed landward of a bulkhead and used to anchor the structure; (see Figure 27). Delta Alluvial deposit, triangular or digitate, formed at river mouth. Design wave height Wave which is used for designing coastal structures such as revetments, breakwaters, jetties, or groins. The wave height and period assists the designer in selecting sizes of armor units and other features of the structure. The design wave will probably not be the maximum wave for economic reasons. Detached breakwaters Breakwaters standing free of the shore; see breakwater . Dike Wall or mound built around low-lying area to control flooding. Disclimax Plant community in which species composition is maintained by continuing disturbance. 146 Dock Place for loading and unloading of vessels/for small boats; see pier. Dolos , dolosses (plural) A type of precast concrete arrror unit used for facing rubble mound structures. Dolphin Cluster of piles; see piling , also Figure 43. Dredge To deepen by removing substrate material; also, mechanical or hydraulic equipment used for excavation. Ebb tide Period between high water and the succeeding low water; falling tide. EIA Environmental impact assessment (or analysis); the analysis of the poten- tial impact of a proposed development project upon its immediate and more distant environment. EIS Environmental impact statement; the actual presentation that results from the eia. Embankment Artificial bank such as a mound or dike, generally built to hold back water or to carry a roadway. Embayment Indentation in shoreline forming open bay. Endemi c Peculiar to particular region or locality; native. Erosion Wearing away of land by natural forces; e.g., by wave action, tidal cur- rents, littoral currents, deflation. Estuary Region near river mouth where fresh river water mixes with salt water of sea. Fetch The distance over unobstructed open water on which waves are generated by a wind having a constant direction and speed. Filter Transitional layer of gravel, small stone, or fabric between fine material of an embankment and revetment armor. 147 Float Floating platform or other device moored to bottom of a waterway. Flood tide Period between low water and the succeeding high water; rising tide. Food chain Dependence of a series of organisms, one upon another, for food; begins with plants and ends with largest carnivores. Forb Herb other than grass. Foreshore Part of the shore lying between crest of seaward berrr and ordinary low water mark. Freeboard Distance between waterline and top deck of a structure or vessel. Fringe marsh A narrow wetland at the edge of a body of water. Gabion Hollow cylinder filled with earth; see revetment. Grass flats Flat areas alternately covered and uncovered by tidal action which sup- port extensive growths of grasslike vegetation. Grave I Loose, rounded fragments cf rock, C.75 to 3in (1.8 to 7.6cm) diameter. Groin, groyne (Bristish) A rigid structure built at an angle (usually perpendicular) from the shore to protect it from erosion or to trap sand. A groin may be further defined as permeable or impermeable depending on whether or not it is designed to pass sand through it. Groin field (also groin system) Series of groins spaced along the shoreline acting together to protect a section of beach. Gribbles Small marine isopod crustacean (UmruDria spp.) that destroys submerged timber. Gulf Large embayment, entrance generally wider than length. Habit Characteristic mode of growth or appearance. 148 Habitat Interacting physical and biological factors which provide at least minimal conditions for one organism to live or for a group of organisms to occur together. Habitat type All the area that presently supports a community or organisms. Harbor Any protected water area affording place of safety for vessels; for the purposes of this study, includes boat basins, marinas, and moorage. Headland High steep-faced promontory extending into sea. Herb Seed-producing vascular plant that produces no woody tissue and dies back at end of growing season. Hook Spit or narrow cape of sand or gravel which turns landward at outer end. Impact An action producing a significant causal effect or the whole or part of a given phenomenon. Impermeable groin Groin through which sand cannot pass; see groin. Individual lot pier One-owner pier usually serving single property. Inlet Water passage to an inland water; or a recess in the shore such as a bay. Internation Great Lakes tidal datum (IGLD) See tidal datum. Invertebrate Animal lacking an internal skeletal structure, e.g., insects, mollusks, crayfish, etc. Isthmus Narrow strip of land, bordered on both sides by water, connecting two larger bodies of land. Jet To place in ground by means of jet of water acting at lower end. Jetty Structure extending into body of water designed to prevent shoaling of channel by littoral materials and to direct or confine stream or tidal flow; See breakwater. 149 Key (also cay) Low insular bank of sand, coral, etc. Lagoon Shallow body of water, usually connected to sea. Levee Usually manm.ade dike or embankment to protect land from inundation. Life ay ale (life stage) The various phases or chances through which an individual passes in its development from the fertilized egg to the mature organism. Lightering buoy Point buoy; tie up for a small craft; see buoys and floats. Littoral Of or pertaining to a shore. Littoral drift Sedimentary material in littoral zone under influence of waves and cur- rents. Littoral transport Movement of littoral drift by waves and currents; includes movement par- allel to and perpendicular to shore. Marina Small harbor or boat basin providing dockage, supplies, and services for small pleasure craft, see harbor. Marine way (also marine railway , launohway) Railway extending into water used to launch or to pull vessels from water; see vamp. Mean high water Average height of high waters over a 19-yr period (MHW). Mean low water Average height of low waters over a 19-yr period (MHW). Mean sea level Averaoe height of surface of sea for all staces of tide over 19-yr period (MSL). Mean tide level Plane midway between mean high water and mean low water (also half-tide level ). Migration Mass movement of animals to and from feeding, reproduction, or nesting areas. 150 Mole Massive land-connected, solid-fill structure of earth (generally revetted) masonry or large stone; see jetty. Monolithic Type of construction in which structure's component parts are bound to- gether to act as one. Moorage Place to make a vessel fast with anchors, cables, etc.; see harbor. Mud Fluid-to-plastic mixture of finely divided particles of solid material and water. Mud flats Low, unvegetated mud substrate that is flooded at high tide and uncovered at low tide. Neap tide Tide occurring near time of quadrature of moon with sun, usually with range 10% to 30% less than mean tidal range. Nekton Macroscopic organisms swimming actively in water; e.g., fish. Neritic zone Relatively shallow water zone which extends from the high-tide mark to edge of continental shelf. Westing Pertaining to brooding eggs or rearing young. Nourishment Process of replenishing a beach; naturally by longshore transport or artificially by deposition of dredged material. Nursery Area where young are born or cared for. Nutrients Elements or compounds essential as raw material for organism growth and development; e.g., carbon, phosphorous, oxygen, nitrogen. Outfall Structure extending into a body of water for the purpose of discharging an effluent (sewage, storm runoff, cooling water). Parapet Low wall built along edge of a structure. 151 Pass Navigable channel through bar, reef, shoal, or between adjacent islands. Pelagic zone Open sea, away from the shore. Periphyton Attached microscopic organisms growing on the bottom or on other sub- merged substrates. Permeable groin Groin with openings large enough to permit passage of appreciable quan- tities of littoral drift; see groin. Phytovlankton Planktonic plant life. Pier A structure, usually of open construction, extending into the water from the shore. It serves as a landing and mooring place for vessels or for recreational uses. Includes trestles, platforms, and docks. Pile Long, heavy timber or section of concrete or metal driven or jetted into earth or seabed for support or protection. Pile cluster Dolphin; group of adjacent piles. Pile dike Dike construction of piles. Pile, sheet Pile with generally slender flat cross section, meshed or interlocked with like members to form wall or bulkhead. Piling Group of piles. Pioneer species One capable of establishing itself in a barren area. Plankton Suspended microorganisms with relatively little power of locomotion that drift in water and are and are subject to action of waves or currents. Point Outer edge of any land area protruding into water, less prominent than cape. 152 Point buoy Mooring buoy, usually for single vessel; see buoys and floats. Port Place where vessels may discharge or receive cargo. Productivity Rate of production of offspring, or fixation of solar energy. Quay Stretch of paved bank or solid artificial landing place parallel to navigable waterway used as loading area. Ramp A uniformly sloping platform, walkway, or driveway. The ramp commonly seen in the coastal environment is the launching ramp which is a sloping platform for launching small craft. Reef An offshore chain or ridge of rock or ridge of sand at or near the sur- face of the water. An artificial reef is a similar chain or ridge built up by man to resemble a natural reef. Retaining wall Wall built to keep bank of earth from sliding or water from flooding; see bulkhead. Revetment A sloped facing built to protect existing land or newly created embank- ments against erosion by wave action, currents, or weather. Revetments are usually placed parallel to the natural shoreline. Ria Long, narrow inlet with depth gradually diminishing inward. Riprap Layer, facing, or protective mound of stones randomly pieced to prevent erosion, scour, or sloughing of structure or embankment; see revetment. River datum Reference plane for river; each river has a characteristic datum. Roadstead (also road) A place less enclosed than a harbor where ships may ride at anchor. Rubble Rough, irregular fragments of broken rock. Rubble-mound structure Mound of random-shaped and random-placed stones protected with cover layer of stones or specially shaped concrete armor units. 153 Sand Rock fragments less than 0.75in (1.9crr) diameter. Scouring effect Removal of underwater material by waves and currents, especially at base or toe of a structure. Seawa I I Structure separating land and water areas, primarily designed to protect land from wave action; see Sedimentation Process of deposition of material, usually soil or organic detritus, in the bottom of a liquid. Sessile Attached to substrate and not free to move about. Shingle Any beach material coarser than ordinary gravel, especially with flat or roundish pebbles. Shoreline, eroding Shoreline which, by wave action, longshore current, or frequent storm activity is losing material. Sill, sandbag A small breakwater used for shore protection which is constructed from sand filled nylon tubes. Sandbag sills are usually placed parallel to the shoreline and just below the intertidal zone. Silt Loose sedimentary materials with rock particles less than 0.05 mm diameter. Slip Berthing space between two piers. Spandrel (bridge) A bridge with a series of arches supporting the roadway. Spawning Production and deposition of eggs, with reference to aquatic animals. Spit Small point of land or narrow shoal projecting into body of water from shore. Spring tide Occurs at or near time of new or full moon and rises highest and falls lowest from mean sea level. 154 Stone, derrick Stone heavy enough to require mechanical means of handling individual pieces, generally 1 ton (C.?l metric ton) and over. Storm tide Rise above normal water level on open coast due to action of wind stress on water surface. Structure support Pilings or other structures with principal function being the support of a structure which extends over the water. Substrate Solid material upon which an organism lives or to which it is attached. Succession Sequence of communities which replace one another in a given area. Taxon (pi taxa) Any taxonomic unit or category of organism; e.g., species, genus, family, order, etc. Terrestrial Growing or living on or peculiar to the land, as opposed to the aquatic environment. Terrigenous Relating to oceanic sediment derived directly from destruction of rocks on earth's surface. Tetrapod A type of precast concrete armor unit with four legs used for facing rubble-mound structures. Tidal datum Plane or level to which elevations or tide heights are referenced. These wary for different coastal regions. Tidal flat The sea bottom, usually wide, flat, muddy, and unvegetated which is exposed at low tide; marshy or muddy area that is covered and uncovered by the rise and fall of the tide. Tide gate An opening through which water may flow freely when the tide or water level is low or high but which will be closed to prevent water from flowing in the other direction when the water level changes. Toe, bulkhead The base of a bulkhead, the lowest part. 155 Tolerance Relative capacity of an organism to endure or adapt to an unfavorable environmental factor. Tombolo Ear or spit connecting an island or structure to the mainland or to another island. Toxicant Substance that kills, injuries, or impairs an organism. Toxicity Quality, state, or degree of the harmful effect resulting from alteration of an environmental factor. Training works Structure to direct current flow; see jetty. Trestle Braced framework of timbers, piles, or steelwork; see pier. Turbidity Deficient in clarity; muddiness, murkiness. Vertebrate Animal having an internal skeletel system. Walers Horizontal members attached to piles in bulkhead; see Figure 27. Wave runup The rush of water up a structure or beach en the breaking of a wave. Weep holes Drainage hole in a structure allowing release of groundwater to prevent a buildup of water behind the structure. Weir jetty An updrift jetty with a low section or weir over which littoral drift moves into a pre-dredged deposition basin which is periodically dredged. Wharf Structure built on shore so vessels may tie alongside. Zooplankton Planktonic animal life. 156 ir US GOVERNMENT PRINTING OFFICE: 1980— 676-972 * □ ©-© Headquarters - Office of Biological Services, Washington, D.C. National Coastal Ecosystems Team, Slidell. La. Regional Offices Area Office U.S. FISH AND WILDLIFE SERVICE REGIONAL OFFICES REGION 1 Regional Director U.S. Fish and Wildlife Service Lloyd Five Hundred Building, Suile 1692 500 N.E.Multnomah Street Portland, Oregon 97232 REGION 2 Regional Director U.S. Fish and Wildlife Service P.O.Box 1306 Albuquerque. New Mexico 87103 REGION 3 Regional Director U.S. Fish and Wildlife Service Federal Building. Fort Snelling Twin Cities, Minnesota 55111 REGION 4 Regional Director U.S. Fish and Wildlife Service Richard B. Russell Building 75 Spring Street, S.W. Atlanta, Georgia 30303 REGION 5 Regional Director U.S. Fish and Wildlife Service One Gateway Center Newton Corner, Massachusetts 02 i REGION 6 Regional Director U.S. Fish and Wildlife Service P.O. Box 25486 Denver Federal Center Denver, Colorado 80225 ALASKA AREA Regional Director U.S. Fish and Wildlife Service 1011 E.Tudor Road Anchorage, Alaska 99503 58 4 DEPARTMENT OF THE INTERIOR U.S. FISH AND WILDLIFE SERVICE 5tf As the Nation's principal conservation agency, the Department of the Interior has respon- sibility for most of our nationally owned public lands and natural resources. This includes fostering the wisest use of our land and water resources, protecting our fish and wildlife, preserving the-environmental and cultural values of our national parks and historical places, and providing for the enjoyment of life through outdoor recreation. The Department as- sesses our energy and mineral resources and works to assure that their development is in the best interests of all our people. The Department also has a major responsibility for American Indian reservation communities and for people who live in island territories under U.S. administration.