CX. >. Av Gale, ae Qo W eS eel ke, Ci e aS C Technical Report CHL-97-17 August 1997 US Army Corps of Engineers Waterways Experiment Station Periodic Inspection of Humboldt Bay Jetties, Eureka, California Report 1 Base Conditions by Robert R. Bottin, Jr, WES William S. Appleton, San Francisco District Approved For Public Release; Distribution Is Unlimited TA 2s »w Bart levies stu te GL -IE Rept. \ Prepared for Headquarters, U.S. Army Corps of Engineers The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. The findings of this report are not to be construed as an official Department of the Army position, unless so desig- nated by other authorized documents. Beane ON RECYCLED PAPER Technical Report CHL-97-17 August 1997 Periodic Inspection of Humboldt Bay Jetties, Eureka, California Report 1 Base Conditions by Robert R. Bottin, Jr. U.S. Army Corps of Engineers Waterways Experiment Station 3909 Halls Ferry Road Vicksburg, MS 39180-6199 William S. Appleton U.S. Army Engineer District, San Francisco San Francisco, CA 94105-1905 Report 1 of a series Approved for public release; distribution is unlimited mv WM 0301 OO9L517? 49 Prepared for U.S. Army Corps of Engineers Washington, DC 20314-1000 ivan US Army Corps of Engineers Waterways Experiment Station GEOTECHNICAL LABORATORY FOR INFORMATION CONTACT: ! PUBLIC AFFAIRS OFFICE is ay Sf ar) Hf. | U.S. ARMY ENGINEER WIROMMEN bs SS] 8 IE / WATERWAYS EXPERIMENT STATION OA Oe ia _ i ae 3909 HALLS FERRY ROAD VICKSBURG, MISSISSIPP1 39180-6199 PHONE: (601) 634-2502 AREA OF RESERVATION « 2.7 sah Waterways Experiment Station Cataloging-in-Publication Data Bottin, Robert R. Periodic inspection of Humboldt Bay jetties, Eureka, California. Report 1, Base conditions /by Robert R. Bottin, Jr., William S. Appleton ; prepared for U.S. Army Corps of Engineers. 48 p. : ill. ; 28 cm. -- (Technical report ; CHL-97-17 rept. 1) Includes bibliographic references. Report 1 of a series. 1. Jetties -- California -- Humboldt Bay. 2. Harbors -- California -- Humboldt Bay. 3. Bays -- California. 4. Humboldt Bay (Calif) I. Appleton, William S. II. United States. Army. Corps of Engineers. III. U.S. Army Engineer Waterways Experiment Station. IV. Coastal and Hydraulics Laboratory (U.S. Army Engineer Waterways Experiment Station) V. Title. VI. Series: Technical report (U.S. Army Engineer Waterways Experiment Station) ; CHL-97-17 rept.1. TA7 W34 no.CHL-97-17 rept.1 Contents Pie fae: 025 0E ie ie eS aS cl HG ie cig ont RAEN SS RN ge Vv Conversion Factors, Non-SI to SI (Metric) Units of Measurement ............ Vi jlea=2 Feiaqavs (io aloyi so eter hes eeens cuctroLecie Urn iets Sean laae ee hea AR rl oeeas eee 1 Work Unit Objective and Monitoring Approach ...................--...-- 1 PEOJECHIbocationtanG els (Oy men erie teenie tee 2 IBUTpOSe Of thle) SLUG) senna Een ein ere 13 2—=Monitonneselantand!Datayeeeee rene terrier etter ter 14 slaxcetingeand) Ground: SUnVCy Sinner elt cere eter er 14 (Senal)ehotocra phan nee oe ieee ern ner tetera 20 Photogrammetric Analysis of Armor Unit Targets ................--.... 20 1Byeay eon ANimaatoye Une SWINK oo ccovocacncadasdesneboocoonooebbeoD0NGCE 23 BSN gocooososccccaddggnedeob doocsebonocGucadueunDoaanodcot 3] RE TEETICES Ess carey eee eee LIEN UNION ee Cee nen se ee ee renee oe cues 32 Tables 1-4 SF 298 List of Figures (ea [Beep Il, IPRS OCCASION. « obo ccacoubdocounseccas0gpoeeasssoneoadogES 3 Figure 2. Concrete monolith structure constructed on south jetty in 1911 ..... 6 Figure 3. Typical cross section of north jetty...........---....----.----- 9 Figure 4. Typical cross section of south jetty ................-..------- 10 Figure5. Typical repairs made to jetties in 1988 ..................--..- 11 Figure 6. | Current project as of December 1994 ................-...+--- 12 Figure 7. Aerial photograph of Humboldt Bay jetties (1997) ...........-.. 13 Figure 8. Figure 9. Figure 10. Figure 11. Figure 12. Figure 13. Figure 14. Figure 15. Figure 16. Figure 17. Figure 18. Figure 19. Figure 20. Figure 21. Figure 22. Diagram of monuments used for survey control at: Humboldt)Bay is catwrmectot cetacean aa ae re Ce ere Typical target established on dolosse at Humboldt Bay .......... Example of a dolos with three targets established ............... Locations of targeted armor units on north jetty ................ Locations of targeted armor units on south jetty ................ Stereo pair photographs for a portion of the north jetty........... Stereo pair photographs for a portion of the south jetty .......... Orthophoto for a portion of the north jetty..................... Representative targeted dolos armor unit positions relativeltonxeny,and|Z;aXCSiar anne e Omer ete eel eee ner: Dolos with angled, mid-shank break .......................-.- Dolos with straight, mid-shank break........................-. Dolos with straight fluke-shank break ........................ Dolos with straight, shank-fluke break......................--- Approximate locations of broken/cracked dolos armor unitsionithe:northyettyan to ears oe a ete eieieetan sero: Approximate locations of broken/cracked dolos armor unitsronithe southyjethyaremmen cee a aee rece eer er rerio Preface The study reported herein was conducted as part of the Monitoring Completed Navigation Projects (MCNP) Program, formerly Monitoring Completed Coastal Projects Program. Work was carried out under Work Unit 11M-7, “Periodic Inspections.” Overall program management for MCNP is accomplished by the Hydraulic Design Section of Headquarters, U.S. Army Corps of Engineers (HQUSACE). The Coastal and Hydraulics Laboratory (CHL), U.S. Amy Engineer Waterways Experiment Station (WES), is responsible for technical and data man- agement and support for HQUSACE review and technology transfer. Program Monitors for the MCNP program are Messrs. John H. Lockhart, Jr., Barry W. Holliday, and Charles B. Chesnutt (HQUSACE). The Program Manager is Ms. Carolyn M. Holmes (CHL). This report is the first in a series that will track the long-term structural response of the Humboldt Bay Jetties, California, to their environment. The information con- tained in this report was gathered as a result of land and aerial survey work con- ducted by Richard B. Davis, Inc., under contract to the Corps of Engineers, and broken armor unit surveys conducted by Messrs. Robert R. Bottin, Jr., Larry R. Tol- liver, and Brian Marble (CHL), and Mr. William S. Appleton, U.S. Army Engineer District, San Francisco (CESPN). The work was conducted during the period September through December 1996 under the general supervision of Dr. James R. Houston and Mr. Charles C. Cal- houn, Jr., Director and Assistant Director, CHL, and under the direct supervision of Messrs. C. E. Chatham, Jr., Chief, Wave Dynamics Division, and Dennis G. Mar- kle, Chief, Wave Processes Branch. This report was prepared by Messrs. Bottin, CHL, and Appleton, CESPN. Director of WES during the investigation and publication of this report was Dr. Robert W. Whalin. Commander and Deputy Director was COL Bruce K. Howard, EN. The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. vi Conversion Factors, Non-Sl to SI (Metric) Units of Measurement Non-SI units of measurement used in figures, plates, and tables of this report can be converted to SI (metric) units as follows: go ie i= ae cece ee EC ene on ee oe Chapter 1 1 Introduction Work Unit Objective and Monitoring Approach The objective of the Periodic Inspections work unit in the Monitoring Completed Navigation Projects (MCNP) research program is to periodically monitor selected coastal navigation structures to gain an understanding of the long-term structural response of unique structures to their environment. These periodic data sets are used to improve knowledge in design, construction, and maintenance of both exist- ing and proposed future coastal navigation projects. These data also will help avoid repeating past design mistakes that have resulted in structure failure and/or high maintenance costs. Past projects monitored under the MCNP program, and/or structures with unique design features that may have application at other sites, are considered for inclusion in the periodic inspections monitoring program. Selected sites are presented as candidates for development of a periodic monitoring plan. Those sites receiving favorable response during MCNP program review are inspected and a monitoring plan is developed and presented for approval. Once the monitoring plan for a site is approved by the field review group and funds are pro- vided, monitoring of the site is initiated. Normally, base conditions are established and documented in the initial effort. The site then is reinspected on a periodic basis (frequency of surveys is based on a balance of need and funding for each monitoring site) to obtain long-term structural performance data. Relatively low-cost remote sensing tools and techniques, with limited ground truthing surveys, are the primary inspection tools used in the monitoring efforts. Most periodic inspections consist of capturing above-water conditions of the struc- ture at periodic intervals using high-resolution aerial photography. Periodic aerial photographs are compared visually to gauge the degree of in-depth analysis required to quantify structural changes (primarily armor unit movement). Data analysis involves using photogrammetric techniques developed for and successfully applied at other coastal sites. At sites where local wave data are being gathered by other projects and/or agencies and these data can be acquired at a relatively low cost, wave data are correlated with structural changes. In areas where these data are not available, general observations and/or documentation of major storms occurring in the locality are presented along with the monitoring data. Ground surveys are limited to the level needed to establish the accuracy of the photogrammetric techniques. Introduction When a coastal structure is photographed at low tide, an accurate permanent record of all visible armor units is obtained. Through the use of stereoscopic, photogrammetric instruments in conjunction with photographs, details of structure geometry can be defined at a point in time. By direct comparison of photographs taken at different times, as well as the photogrammetric data resolved from each set of photographs, geometric changes (i.e. armor unit movement and/or breakage) of the structure can be defined as a function of time. Thus, periodic inspections of the structures will capture permanent data that can be compared and analyzed to deter- mine if structure changes are occurring that indicate possible failure modes and the need to monitor the structure(s) more closely. The Humboldt Bay Jetties, Eureka, CA, were nominated for periodic monitoring by the U.S. Army Engineer District, San Francisco (CESPN). An additional CESPN project has been monitored previously under the Periodic Inspections work unit. Conditions have been defined for the Crescent City Harbor Breakwater, Crescent City, California (Markle, Melby, and Kendall 1995). Project Location and History With the discovery of Humboldt Bay in 1849 by the Josiah Gregg party, came a fever of land speculation in San Francisco (O’Hara and Graves 1991). The Bay is located on the northern California coast (Figure 1). It is approximately 22.5 km (14 miles)! long (north to south) and varies from 0.8 to 5.6 km (0.5 to 3.5 miles) in width. The discovery of the Bay improved access to trade with the Trinity gold mines. Passengers aboard the schooner Laura Virginia, bound for Humboldt Bay, hoped that they would be able to establish businesses which would supply the mines. Hans Henery Buhne piloted the schooner into Humboldt Bay in 1850, after spending days in treacherous seas attempting to find a navigable channel through the crescent-shaped sandbar blocking the Bay entrance. This piloting experience was the beginning of a long battle with the sea to create a stable navigable channel into Humboldt Bay. During the 30 years following the successful piloting of the Laura Virginia into Humboldt Bay, vessels relied on experienced pilots, many of whom were part of Buhne's piloting business, to aid in navigating through the ever-shifting crescent- shaped sandbar at the entrance to the Bay. However, the severe wave climate of the northern California coast, effects of the bar on wave breaking, and the frequent shifting of channels through the bar often prevented deep-draft vessels from servic- ing the growing timber and agricultural businesses in the area. As commerce increasingly felt the constraints placed on it by the unpredictability of navigation into the Bay, concerns were voiced and drew the attention of the Federal Govern- ment and ultimately the U.S. Army Corps of Engineers. 1Units of measurement in the text of this report are shown in SI (metric) units, followed by non-SI (British) units in parentheses. In addition, a table of factors for converting non-SI units of measure- ment used in figures in this report to SI units is presented on page vi. Chapter 1 Introduction =a q 4 | % LOCATION MAP 80 CJ 6c SCALE Im MILES sila ENA CANIIBAL RD- VICINITY MAP 1 °o 1 2 3 4 SCALE IN MILES Figure 1. Project location With the successful construction of north and south jetty structures to stabilize the entrance to Yaquina Bay, OR, during the period 1881-1892, the Corps believed that a similar jetty structure would stabilize the spits at the entrance to Humboldt Bay and help to establish a reliable navigation channel by confining the tidal cur- rents. Construction of the south jetty at Humboldt Bay began in 1889. The con- struction technique involved building a trestle over the footprint of the proposed structure and using specially designed railcars to then dump rock weighing up to 7,260 kg (8 tons). Scour mats made from willow branches were fabricated and submerged by loading them with rock. The dumped material was allowed to assume its angle of repose, but heavy seas would flatten the slope further. Slope flattening was combated with the placement of more material. Later, as the project pro- gressed, it was found that scouring was occurring around the trestle piles faster than the brush mats could be placed. It was soon discovered that a 0.9-m- (3-ft-) thick layer of small stones could be used as scour protection and could be placed more rapidly than brush mats. Chapter 1 Introduction In 1890, it was observed that the stability of the north spit was being compro- mised and that the channel was changing positions despite completion of the 930-m- (3,040-ft-) long south jetty. A north jetty structure then was deemed necessary. Construction of the north jetty began in 1891 and employed the same construction techniques as those used to construct the south structure. The north jetty, although started after the south jetty construction had begun, was completed in 1897, before completion of the south jetty. The total project was completed in 1899. The south jetty had a length of 2,258 m (7,408 ft), while the north jetty had a length of 2,460 m (8,068 ft). The jetties were spaced approximately 640 m (2,100 ft) apart and created a stable channel with depths averaging 7.6 m (25 ft).! In 1899, the average cross section for the south jetty had the following charac- teristics (U.S. Army Engineer District (USAED), Los Angeles 1986): The average cross section of the north jetty in 1899 had the following characteristics: Ocean-side slope 1V:1.9H Channel-side slope 1V:2.4H Shape (cross sectional) Trapezoidal By 1910, both jetties had been battered down to below mllw and shoals at the seaward ends of the jetties had become so severe that the structures' heads were buried in sand. Reconstruction of the structures was approved in 1910, and con- struction was initiated in 1911. Jetty restoration involved the use of the existing ‘All elevations (el) and depths cited herein are in meters (feet) referred to mean lower low water (mllw). Chapter 1 Introduction jetties as a core and building a new structure over them. The south jetty had the following reconstruction design (USAED, Los Angeles 1988): Ocean-side slope 1V:2H Channel-side slope 1V:2H Shape (cross sectional) Trapezoidal Height, station 44+00 to 67+00 +4.5 m (+14.8 ft) Height, station 67+00 to 91+00 +5.2 m (417.2 ft) Height, station 91+00 to end +5.8 m (+19 ft) Three classes of rock were used for the reconstruction, and the material was placed according to specifications established by the Corps. Class I stones con- sisted of armor stone weighing from 9,070 to 18,140 kg (10 to 20 tons). These stones were used exclusively for armoring the ocean-side slope of the outer 732 m (2,400 ft) of jetty. Class Il stones, weighing from 450 to 9,070 kg (0.5 to 10 tons) each, made up the majority of the south jetty reconstruction, the larger of these stones being used for armoring the structure slopes shoreward of the Class I stones. Class III stones, weighing from 1.4 to 227 kg (3 to 500 Ib), were used for core mate- rial as well as to level off the cap of the existing structure in preparation for the placement of a concrete cap that was 0.6 m (2 ft) thick and 6.1 m (20 ft) wide. Embedded within the cap were wooden ties used for the placement of rails for a crane and rail cars. The head of the south jetty, which had been subjected to some of the most severe damage, was reinforced with a concrete monolith that was 9.1 m (30 ft) wide and 4.3 m (14 ft) deep (Figure 2). The 861,825-kg (950-ton) monolith was placed in the center of the head and armor stones up to 18,140 kg (20 tons) were laid up adja- cent to the monolith. The el of the head was raised to +7.3 m (+24 ft) and the voids between the armor stones were filled with stones of not less than 227 kg (500 Ib) in weight. The north jetty was reconstructed after completion of work on the south struc- ture. The original structure was used as the core for the restoration, with the completed cross section being trapezoidal with a concrete cap. Also, a concrete monolith, weighing 952,540 kg (1,050 tons), was poured in the center of the head of the north jetty. The range of stone size within each class varied slightly from what Chapter 1 Introduction CONCRETE MONOLITH A wk Ny 205 © ee. OY in oy peewee: Foy nn ae eee -PLAN VIEW Figure 2. Concrete monolith structure constructed on south jetty in 1911 was specified for the south jetty, but construction techniques and specifications were the same. The north jetty had the following reconstruction design: Ocean-side slope 1V:1.5H Channel-side slope 1V:1.5H Shape (cross sectional) Trapezoidal 44.3 m (414 ft) With the exception of repairing a breach in the south jetty in 1920 and repairing some north spit shore protection in 1922, no significant work was done on the struc- tures until 1925. Between 1925 and 1927, parapet walls were added to each jetty on the south sides of the caps due to wave exposure. In addition, mass concrete was Chapter 1 Introduction poured on the channel-side slopes to stabilize the armor stone. The parapet walls were typically 1.2 m (4 ft) high and 1.8 m (6 ft) wide. Numerous repairs occurred on both structures between 1927 and 1972. The jetties experienced full breaches as well as extensive damage to both channel- and ocean-side slopes. During the period 1931 to 1932, extensive repairs were made to the jetty heads using precast concrete blocks weighing approximately 14,515 kg (16 tons). The blocks were used to rearmor the heads of the structures as well as provide formwork for future monolith pours. For a time these blocks were used in place of armor stone due to the lack of suitable stone; however, it was soon found that the blocks were easily moved by wave action. The south jetty was breached again in 1939 at stas 42+50 and 48+80 and repaired with mass concrete. A partial breach that occurred in the same year on the north jetty, just shoreward of the concrete monolith, also was repaired with mass concrete. In 1950, the south jetty was breached again between stas 85+63 and 86+35. It was repaired in 1951 with mass concrete and twelve 90,720-kg (100-ton) concrete blocks. In 1957, both structure heads had extensive areas that were void of armor stone as a result of gradual deterioration over a considerable period of time during which no maintenance was performed. Consequently, two to three layers of 13,610- and 22,680-kg (15- and 25-ton) tetrapods were used to armor the jetty heads. The tetra- pods placed around the heads had the following characteristics: North Jetty | Seaward of station 73+50 (Channel-side): 22,680-kg (25-ton) tetrapods’ Seaward of station 74+10 (Ocean-side): 22,680-kg (25-ton) tetrapods’ South Jetty | Seaward of station 89+00 (Channel-side): 13,610-kg (15-ton) tetrapods’ ‘Slope of tetrapods: 1V:1.5H. Placement of the armor units was consistent with observed wave exposure from the southwest. Also, 90,720-kg (100-ton) concrete blocks were cast on the monoliths and slid into the voids of the slope. However, despite repair and improvement work, both jetties continued to experience extensive damage. Following the severe storm seasons of 1958 and 1959, rehabilitation of both jetties took place from 1960 to 1963. Jetty trunks were repaired with 10,890-kg (12-ton) stones placed on a 1V:1.5H slope in the eroded areas, while jetty heads were reconstructed using 18,140-kg (20-ton) concrete blocks as formwork for concrete pours. Two-hundred- and-fifty 90,720-kg (100-ton) concrete blocks were placed around the seaward tip of the south jetty. The head of the north jetty was armored further with armor stones grouted with concrete. The el of the north jetty was raised to +7.6 m (+25 ft), Chapter 1 Introduction and the elevation of the south head was raised to +7.9 m (+26 ft). Prior to this, both heads had els of +5.8 m (+19 ft). From 1963 to 1965, the heads of the jetties continued to experience damage. Most of the 90,720-kg (100-ton) concrete blocks had washed away, and portions of the concrete monoliths in both jetties were experiencing erosion. As a result, in 1967, CESPN directed the U.S. Army Engineer Waterways Experiment Station (WES) to undertake the design, construction, and testing of a hydraulic model of the seaward ends of the structures to determine the optimum design for protecting these structures from further deterioration. Following the total destruction of both jetty heads in 1969, reconstruction of the heads, based on WES model results (Davidson 1971), was begun in 1971. Repairs included the reconstruction of both monolithic structures and the placement of 38,100-kg (42-ton) dolosse around the seaward portion of each jetty head. The north jetty received 1,292 dolosse (4 were unreinforced, 1,271 were steel-reinforced, and 17 were steel-fiber-reinforced). The south jetty received 1,445 dolosse (22 of which were unreinforced and the remaining number were steel reinforced). The shoreward transition section of each jetty head was armored with 39,000-kg (43-ton) dolosse (967 were used on the north jetty, and 1,090 were used on the south structure). The dolosse were placed in two layers to achieve maximum hydraulic stability, and a concentration of 11 dolosse per 9.3 sq m (100 sq ft) of slope was used for each layer. Dolos rehabilitation on the Humboldt Bay jetties was used as a test case to eval- uate the strength of steel-cage reinforced dolosse, fiber-reinforced dolosse, and non- reinforced dolosse. In general, it was determined that the durability of the reinforced dolosse was greater than those without reinforcement. However, the strength of both the nonreinforced and reinforced sections was found to be approximately equal (Barab and Hanson 1974). Knowledge obtained from the testing of dolosse on the Humboldt Bay jetties was later applied to the dolos rehabilitation project on the outer breakwater at Crescent City, CA. Following the armoring of the structure heads with dolosse, damage to the struc- ture has been primarily along the trunk reaches of the jetties. To this point, the dolos fields appear to be performing well and no extensive repair work has been necessary on either jetty since completion of the work. Figures 3 and 4 show typical cross sections for the north and south jetties, respectively. In 1988, substantial repair work was done on both of the jetties. Repairs involved the use of approximately 181,440 kg (2,000 tons) of stone for slope repair and 765 cu m (91,000 cu yd) of concrete for the filling of voids in the structure (USAED, San Francisco 1988). Figure 5 shows typical repairs made in 1988, and Figure 6 provides a plan view of Humboldt Bay, the jetty structures, and the naviga- tion channels as of December 1994. The most recent work on the jetties was undertaken as emergency repairs in 1995. It involved the filling of an extensive void in the cap and the repositioning of Chapter 1 Introduction 54'-90' AT JETTY SR Steen HEAD ONLY 42 TON DOLOSSE (2 LAYERS) SLOPES VARIES SLOPE VARIES ROCK ON SOUTH JETTY ONLY (BOTH SIDES) STA 67+00 TO END OF NORTH JETTY HEAD CROSS SECTION NOTE: CONC CAP IS 12° + WIDE SOUTH JETTY FROM 38+00 TO 48+00 VARI 16° + MLLW eels FS SLOPES VARIES 7 aa, a Te WOOD MATS WOOD MATS AT STA 30+00 NORTH JETTY UNDER 7.5° BEDDING STA 0+00 TO 67+00 (NORTH JETTY) CROSS SECTION Figure 3. Typical cross section of north jetty armor stone on the south jetty. No extensive repairs, however, have been made to the structure since 1988 (USAED, San Francisco 1996). The Humboldt Bay jetties are currently inspected annually by San Francisco District Corps personnel. These inspections include both a thorough walk-over of the structure as well as a subsurface investigation using side-scan sonar and dive teams. This level of monitoring has helped to ensure that the structures receive timely repairs, thereby avoiding a loss of functionality and catastrophic failure. Chapter 1 Introduction 9 54'-90' AT JETTY 42 TON DOLOSSE HEAD ONLY 42 TON DOLOSSE (2 LAYERS) (2 LAYERS) SLOPES VARIES SLOPE VARIES ROCK ON SOUTH JETTY ONLY (BOTH SIDES) STA 84+00 TO END OF SOUTH JETTY HEAD CROSS SECTION NOTE: CONC CAP IS 12° + WIDE SOUTH JETTY FROM 38+00 TO 48+00 SLOPE VARIES SLOPES VARIES 1.570 2.5 Lp Lt i ad, MLLW. JV 6 ——> ¢ WOOD MATS MATS AT STA 43+24 (SOUTH JETTY NO BEDDING) STA 64+72 mats | sta 41+60 STA 0+00 TO STA 84+00 CROSS SECTION Figure 4. Typical cross section of south jetty Additional history on the Humboldt Bay jetties may be obtained from Bottin (1988). The current lengths of the north and south jetties are 2,225 and 2,741 m (7,400 and 8,993 ft), respectively. Figure 7 shows an aerial view of the jetties in September 1996. 10 Chapter 1 Introduction APPROXIMATE LEVEL OF SAND BACKING SOUTH SIDE OF STRUCTURE BETWEEN STATIONS 0+00 TO 46+00 TYPICAL SECTION OF CAVITY TO BE FILLED WITH CONCRETE FABRIC FRAMEWORK TO BE USED TO LINE CAVITY APPROXIMATELY 16° NOTE: SIZES OF ROCK AND THICKNESS OF CONCRETE CAP AND APRON MAY VARY MEDIUM DENSE TO DENSE, POORLY GRADED FINE SAND FOUNDATION TYPICAL REPAIR SECTION SHOWING EXAMPLE OF CAVITY (SOUTH JETTY-STA. 41 +20 TO STA 41 +70) TYPICAL CAP VOID TO BE FILLED WITH CONCRETE VARIES APPROXIMATE LEVEL OF SAND BACKING NORTH SIDE OF NORTH STRUCTURE BETWEEN STATIONS 0+00 TO 53+00 APPROXIMATELY 16° P CONCRETE CA\ — Vy 0.0" MLLW Vv CONCRETE APRON NOTE: SIZES OF ROCK AND THICKNESS OF CONCRETE CAP AND APRON MAY VARY MEDIUM DENSE TO DENSE, POORLY GRADED FINE SAND FOUNDATION TYPICAL REPAIR SECTION SHOWING TYPICAL CAP VOID (NORTH & SOUTH JETTY) MISSING ARMOR TO BE REPLACED APPROXIMATE LEVEL OF SAND BACKING SOUTH SIDE oe ae VARIES OF STRUCTURE BETWEEN STATIONS 0+00 TO 46+00 4 Ji. APPROXIMATELY 9 16° . -0' MLLW. V0.0" MLLW CONCRETE APRON 2 NOTE: SIZES OF ROCK AND THICKNESS OF CONCRETE CAP AND APRON MAY VARY MEDIUM DENSE TO DENSE, POORLY GRADED FINE SAND FOUNDATION TYPICAL REPAIR SECTION SHOWING MISSING ARMOR TO BE REPLACED (NORTH JETTY) Figure 5. Typical repairs made to jetties in 1988 Chapter 1 Introduction 11 ARCATA CHANNEL 150 FT. WIDE, 18 FT. DEEP (Not Used) : oe TURNING BASIN O00 FT WIDE, }IOO FT LONG 35 FT DEEP Ss — OA - SAMOA CHANNEL 3 ae ase ©) [SOO FT. WIDE, 35 FT. DEEP = i K a Veet = = Rapes DN ie WS, ¢ : EUREKA CHANNEL =< | WIDEN TURNS es eo : BAR AND ENTRANCE GHANMWEL ct — ————$— 1600 F is pages 7 WIDE, Qe : ANCHORAGE GREA (NOT BEING MAINTAINED) é 4 S fe Op 1200 FT XIZO0 FT, 35 FT. DEEP IN NORTH BAY p (BETWEEN ENTRANCE CHANNEL AND GUNTHER ISLAND) arg are TT GONC. PLATFORM paRartT ——ee Soy 216.0 CROSS SECTION NORTH AND SOUTH SETTIES VIEW iS SEAWARD —t i ‘ CEES pleucbicnc Pes CHANNEL SIDE. SOLOSSE Z z : i = Le (Not 10 Seaie) FIELDS LANDING CHANNEL i i Re : iC aE [300 FT. WIDE, 26 FT. DEEP. = Wi aE 4 3 . pon y - Fields Landing .2 >. : ia UT SD Se _ oF r “A'Stone Fn — TURNINCHBASIN CROSS SECTION Tow of 22 on = CP ee oonEwel aed NORTH AND SOUTH JETTY HEADS BASE POINT OF MILEAGE 1S 1800 FT. SHORE WARD OF SOUTH JETTY BEACON DETERMINED FROW DATHYMETRIC 3 TOPOGRAPHIC SURVEYS OF JULY 4 GCPTIMDER 1900 Les ¢ IQ.) HUMBOLDT HARBOR AND jes FOLLOWING CHANNELS HAVE SEEN PARTIALLY DREDGED: 4 { BAY, CALIFORNIA SAMOA CHANNEL SETWEEN MILE 4.29 ANO MILE 5.84 300 FT. WIDE, 30 FT. DEEP. EUREKA CHANNEL BETWEEN MILE ¢.29 AND MILE 5.00 SCALE IN FEET 4CO FT. WIDE, 30F7 DEER 5000 10000 15000 NORTH BAY CHANNEL SETWEEN MILE 0.75 AND MILE 4.29 SO0FT, WIDE, 30 FT DEEP U.S. ARMY ENGINEER DISTRICT, SAN FRANCISCO CORPS OF ENGINEERS ot i i SAN FRANCISCO, CALIFORNIA Mi i 1 DECEMBER 1994 Figure 6. Current project as of December 1994 Chapter 1 Introduction Figure 7. Aerial photograph of Humboldt Bay jetties (1997) Purpose of the Study Purposes of the study reported herein were as follows: a. Develop methods using limited land-based surveying, aerial photography, and photogrammetric analysis to assess the long-term stability response of the concrete dolos armor units on the heads of the Humboldt Bay jetties. b. Conduct land surveys, broken armor unit inspections, aerial photography, and photogrammetric analyses to accomplish the following: (1) Test and improve developed methodologies and accurately define armor unit movement above the water line. (2) Establish base conditions for the jetties' armor units which can be revisited in the future under the Periodic Inspections work unit. Chapter 1 Introduction 13 14 2 Monitoring Plan and Data The objective of the monitoring effort in the Periodic Inspections work unit was to establish base level data upon which long-term stability response of the Hum- boldt Bay jetties could be defined through periodic inspections. Concrete dolos armor units on the seaward ends of the jetties were monitored. This included 181 m (593 ft) of the seaward portion of the north jetty (sta 84+00 - 89+93) and 213 m (700 ft) of the seaward portion of the south jetty (sta 67+00 - 74+00). The monitor- ing plan consisted of targeting and ground surveys, aerial photography, photogram- metric analysis of armor units above the waterline, and a ground-based broken armor unit survey. Targeting and Ground Surveys Points were required to serve as control (both horizontal and vertical reference) for the ground-based survey work as well as the photogrammetric work on the jet- ties. Corps of Engineers brass disk monuments, as well as stationing schemes, had already been established on the Humboldt Bay jetties during previous surveys. The control survey for this study, therefore, made use of the existing monuments and adopted the existing stationing scheme. Ground surveys were initiated from known monuments on land which included stations CA 01 07, CA 01 09, and CA 01 QB as shown in Figure 8. Using global positioning system control surveying and elec- tronic land surveying techniques, positions and elevations of the existing three monuments on each structure (Figure 8) were checked and reestablished. Positions and elevations of the control points are shown below. Horizontal positions are based on the California State Plane Coordinate System and all elevations are refer- enced to mllw datum. Chapter 2 Monitoring Plan and Data : DRAWING NOT TO SCALE CA O01 09 90+05.21.-" CA 01 QB 6 = BRASS DISK CONTROL STATION @ CA 01 07 Figure 8. Diagram of monuments used for survey control at Humboldt Bay Chapter 2 Monitoring Plan and Data 15 16 Land Monuments CA 01 07 +598.975 (+1965.14) CA 01 09 +38.173 (4125.24) CA01 OB 114.176 (646.51) North Jetty Monuments 54400 Se 68+00 +6.593 (+21.63) 74+00 +9.629 (+31.59) In addition, targets were established on selected dolos armor units to serve as control to check the accuracy of the photogrammetric work. Targets were 20.3 cm (8 in.) in diameter and divided into four quadrants, which were painted alternately white and black. A typical target is shown in Figure 9. This style of contrasting target provides a precise center point for which measurements can be made by both land and photogrammetric surveys. A high quality epoxy-based marine paint was used to minimize the need for repainting, and a 0.64-cm (1/4-in.) hole was drilled at the center of each target for identification in subsequent surveys. A total of 34 dolosse on the north jetty and 33 dolosse on the south jetty were selected for targeting. Fifteen dolosse on the north jetty were painted with three targets (dolosse 101 - 115) and nineteen dolosse were painted with a single target (dolosse 1 - 19). On the south jetty, 16 dolosse were painted with three targets (dolosse 201 - 216) and 17 dolosse were painted with a single target (dolosse 51 - 67). An example of a dolos with three targets is shown in Figure 10. Note the tar- gets are labeled A, B, and C. Three targets on individual armor units allow for very precise measurements depicting individual armor unit movement. Armor units selected for targeting were distributed along the length of the jetties on both the sea sides and channel sides of the structures and around the heads. They were also dis- tributed from the crest to the waterline. Figures 11 and 12 show the locations of targeted armor units on the north and south jetties, respectively. Units chosen for targeting had flat surfaces close to horizontal to maximize their visibility in aerial photography and allow for accurate representation of armor unit movement. Chapter 2 Monitoring Plan and Data Figure 9. Typical target established on dolosse at Humboldt Bay Figure 10. Example of a dolos with three targets established Chapter 2 Monitoring Plan and Data 17 Ayef you uo s}iun JoWJe payabie} Jo suoeo07 “14 aunbi4 x o (a) ae] = 6 c & ao D ¢ = S = c S = N is 2 o © de (6) LADUVL FIONIS HLIM SO1Od [) SLADYVL AIdILNIN HLIM SO1Od O Ayal ujnos uo stun owe peje6ie} Jo suoyweo07 °Z} eunbil4 JADYVL FIONIS HLIM SO1Od ()§ SLADYVL ATdILNIN HLIM SO10G ip aT a A I ne aren ae 4a o a ne} c o = x a D & = S 5 f= S = N Be © 2 oO a is 2) 20 Ground surveys of the concrete armor unit targets were conducted during the period 9-12 September 1996. Target coordinates were established using standard surveying techniques. The purpose of armor unit targeting and target surveys was to generate a set of control data by which the accuracy of the photogrammetric sur- vey work could be validated and defined. Ground survey data obtained for the armor unit targets are presented later in this report, where they are compared to the photogrammetric survey data results. Aerial Photography Aerial photography is a very effective means of capturing images of large areas for later analysis, study, visual comparison to previous or subsequent photography, or measurement and mapping. Its chief attribute is the ability to freeze a moment in time, while capturing extensive detail. Aerial photography was obtained along the Humboldt Bay jetties with a Wild RC-8 aerial mapping camera (9-in. by 9-in. format). Black and white mapping pho- tos were secured from a helicopter flying at low altitude (91.4 m (300 ft)), which resulted in high-resolution images and contact prints with scales of 2.54 cm (1 in.) on the photograph equal to 15.2 m (50 ft) in the prototype. Photographic stereo pairs were obtained during the flights. Flight lines were run parallel to the center- lines of the structures. Typical stereo pairs secured for the north and south jetty heads are shown in Figures 13 and 14, respectively. Aerial photography was obtained on 15 September 1996, three days after the ground survey was completed. Photogrammetric Analysis of Armor Unit Targets When aeria! photography is planned and conducted so that each photo image overlaps the next by 60 percent or more, the two photographs comprising the over- lap area can be positioned under an instrument called a stereoscope, and viewed in extremely sharp three-dimensional detail. If properly selected survey points on the ground have previously been targeted and are visible in the overlapping photogra- phy, very accurate measurements of any point appearing in the photographs can be obtained. This technique is called photogrammetry. The stereo pair images obtained during aerial photography for the Humboldt Bay jetties were viewed in an Analytical Stereoplotter, and stereomodels were oriented to the control point data previously obtained. In the stereomodel, very accurate hori- zontal and vertical measurements can be made of any point on any armor unit appearing in the print. The stereomodel was used for all photogrammetric compila- tion and the development of orthophotography. Orthophotos combine the image characteristics of a photo with the geometric qualities of a map. The digital orthophoto is created by scanning an aerial photo with a precision image scanner. The scanned data file is digitally rectified to an Chapter 2 Monitoring Plan and Data Chapter 2 Figure 13. Stereo pair photographs for a portion of the north jetty Monitoring Plan and Data 21 22 Figure 14. Stereo pair photographs for a portion of the south jetty Chapter 2 Monitoring Plan and Data orthographic projection by processing each image pixel. The image is free from skewness and distortion, and therefore, precise horizontal measurements may be obtained with an engineer scale. Orthophotos were prepared for the dolos armor unit fields on the seaward ends of both the north and south jetties at Humboldt Bay. An example of an orthophoto for a portion of the north jetty is shown in Figure 15. Orthophotos were produced on mylar sheets at a scale of 1:240. A photogrammetric analysis of the armor unit targets was conducted and x, y, and z (easting, northing, and el) coordinates were obtained. Data from the dolosse which had three targets were compared to corresponding data derived during the ground surveys to establish the accuracy of the photogrammetric work. Ground survey data and aerial survey data are compared in Table 1. The table shows very close comparison between ground and aerial survey data. Differences between ground and aerial values, for the majority of the targets, were 0.61 cm (0.02 ft) or less. Maximum differences were 1.52 cm (0.05 ft) for both the horizontal and ver- tical positions; however, this level of difference occurred for only 5.4 percent of the targets for the horizontal and 6.5 percent of the targets for the vertical position. Seventy-eight percent of all horizontal target positions, and 80 percent of all vertical target positions, were within 0.91 cm (0.03 ft). As a result of the photogrammetric analysis, aerial data obtained for the dolosse with single targets are shown in Table 2. Additional analysis was conducted for the dolosse with three targets. With the x, y, and z (easting, northing, and el) coordinates defined for each target on the various armor units, the centroids of each targeted armor unit were computed. In addition, the position of each armor unit relative to the x, y, and z axes was determined. Fig- ure 16 shows the orientation of representative armor units to the three axes. The centroid of each targeted dolos and each armor unit's orientation (rotation angle relative to x, y, and z) are presented in Table 3 for the aerial survey results. These are base level conditions from which comparisons can be made in future surveys. Full-scale hardcopies of aerial photographs and orthophotos are on file at the authors’ offices at WES and CESPN. In addition, all photogrammetric compilations and analyses have been stored on diskettes in Intergraph files for future use. In summary, very detailed and accurate information relative to the dolos armor unit positions for the Humboldt Bay jetties have been captured by means of aerial photo- graphy and photogrammetric analysis. Data are stored and can be retrieved and compared against data obtained during subsequent monitoring. Thus, armor unit movement may continue to be quantified precisely in future years. Broken Armor Unit Survey On 17-18 September 1996, a survey of broken/cracked dolos armor units above the waterline was conducted on the seaward portions of the north (sta 84+00 - 89+93) and south (sta 67+00 -74+00) jetties. During the inspection, each broken armor unit was identified and photographed, and its approximate location relative to breakwater station and distance from a baseline was recorded. The baseline was the Chapter 2 Monitoring Plan and Data 23 Ayef you ay} Jo uood e 40} o}oydoyO ‘s} einbi4 Chapter 2 Monitoring Plan and Data 24 LO¢d SO10d sexe Z pue ‘A ‘x 0} aAljejad SUOI}ISOd lun JoWe Sojop payabie} avejueseiday 9g} einbi4 + GO SO VO 25 Chapter 2 Monitoring Plan and Data 26 approximate center line of the structure. At the heads of the structures the baselines were projected seaward along the axis of the jetties. Thirty-four broken or cracked dolosse (seventeen on each jetty) were identified during the walking survey. Armor units with hairline cracks on one side were not counted; only those that were cracked all the way through were considered a break for recording purposes. Breaks were categorized as occurring in the shank or the fluke and as straight across or at some angle to the dolos limb. The shank is the central beam of a dolos, and the flukes are the beams on the ends of the armor unit. The broken units on the north jetty con- sisted of seven mid-shank breaks, eight shank-fluke breaks (shank broken in vicinity of fluke), and five fluke-shank breaks (fluke broken in vicinity of shank). One unit had two breaks. Breaks on the south jetty were characterized as follows: two units, mid-shank breaks; eight units, shank-fluke breaks; and seven units, fluke-shank breaks. Of the 35 breaks, 27 were straight breaks and 8 were angled breaks (approximately 45 deg or greater). Representative broken dolosse are shown in Figures 17-20. Approximate locations of the broken/cracked dolos armor units are shown in Figures 21 and 22, respectively, for the north and south jetties; and detailed data obtained during the broken armor unit inventory are shown in Table 4. Armor unit numbers identified in Figures 21 and 22 correspond to those listed in Table 4. As shown on the figures, broken units are concentrated along the seaward ends of the jetties. Eighty-eight percent of the broken units on the north jetty and seventy-one percent of those on the south jetty are located around the monolithic structures at the jetty heads. In addition, more broken dolosse were observed on the south sides of the structures than on the north. If the approximate center lines of the jetties are projected seaward along the axes of the structures, 59 percent of the broken units on the north jetty and 65 percent of those on the south jetty are located on the southern side of the jetties. With regard to distance downslope from the jetty caps, most the broken dolosse appear to be located in the active wave zone. Detailed data obtained during the broken armor unit survey will allow for an accurate indication of new breaks when the structure is revisited at some point in the future. Chapter 2 Monitoring Plan and Data -shank break m Dolos with angled Figure 17. -shank break m ight, Dolos with strai Figure 18 27 Chapter 2 Monitoring Plan and Data -shank break ight fluke Dolos with stra igure 19. F Dolos with straight, shank-fluke break Figure 20. Chapter 2 Monitoring Plan and Data 28 Aa! YOU aU} UO s}lUN JoWWJe Sojop payx9e10/UEx0Ig Jo SUOeD0] ayeWIXOIddy “|Z ein6i4 ee They: v we EM o Chapter 2 Monitoring Plan and Data Ayal uynos ay} uO sylUN JOWe SO|Op pex9e10/UExOIg JO SUOHedO} ayewIXoIddy “Zz einBi4 o £ o ja) ne] = o c a] a D ¢ : S = = S = N i 2 a o £ (S) my oN 4 ©. ~AS 3 Summary SS The Humboldt Bay jetties have experienced a long history of damage and sub- sequent repairs since original construction was completed in 1899. Rehabilitations were completed in 1911, 1927, 1932, 1939, 1950, 1957, 1963, 1971, 1988, and 1995. These rehabilitations consisted of the construction and/or installation of con- crete monoliths, parapet walls, mass concrete, stone, concrete blocks, tetrapods, and dolosse. Since the dolos rehabilitation of the heads of the jetties in 1971, damages have been primarily along the trunk (stone) reaches of the jetties. No extensive work has been required along the dolos fields since their construction. Prior to this study, no sound, quantifiable data relative to the movement or positions of the dolos concrete armor units had been obtained for the jetties. Under the current Periodic Inspections work unit of the Monitoring Completed Navigation Projects Program, data from limited ground-based surveys, aerial photo- graphy, and photogrammetric analysis have been obtained to establish very precise base level conditions for the seaward dolos-covered portions of the Humboldt Bay jetties. Accuracy of the photogrammetric analysis was validated and defined through comparison of ground and aerial survey data on control points and targets established on the structures. A method using high-resolution, aerial stereo photo- graphs, a stereoplotter, and Intergraph-based software has been developed to ana- lyze the entire above-water concrete armor unit fields and quantify armor positions and subsequent movement. A detailed broken armor unit survey conducted during the current effort has resulted in a well-documented data set that can be compared to subsequent survey data. Now that base (control) conditions have been defined at a point in time and methodology has been developed to closely compare subsequent years of high- resolution data for the Humboldt Bay jetties, the site will be revisited in the future under the Periodic Inspections work unit to gather data by which assessments can be made on the long-term response of the structure to its environment. The insight gathered from these efforts will allow engineers to decide, based on sound data, whether or not closer surveillance and/or repair of the structures might be required to reduce their chances of failing catastrophically. Also, the periodic inspection methods developed and validated for these structures may be used to gain insight into other Corps' structures. Chapter 3 Summary 31 References Barab, S., and Hanson, D. (1974). “Investigation of fiber reinforced breakwater armor units, an international symposium,” Fiber Reinforced Concrete Publica- tion SP-44, American Concrete Institute, Detroit, MI. Bottin, R. R., Jr. (1988). “Case histories of Corps breakwater and jetty structures; Report 1, South Pacific Division,” Technical Report REMR-C0-3, U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS. Davidson, D. D. (1971). “Proposed jetty head repair sections, Humboldt Bay, Cali- fornia; hydraulic model investigation,” Technical Report H-71-8, U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS. O’Hara, P., and Graves, G. (1991). Saving California's coast - Army Engineers at Oceanside and Humboldt Bay. Arthur M. Clark Company, Spokane, WA. Markle, D. G., Melby, J. A., and Kendall, T. R. (1995). “Periodic inspections of dolosse on Crescent City Breakwater, Crescent City, California; Report 1, moni- toring data for period 1989-1993,” Technical Report CERC-95-5, U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS. U.S. Army Engineer District, Los Angeles. (1986). “Comprehensive condition sur- vey, north and south jetties, Humboldt Harbor, Humboldt County, CA,” Main Report and Appendixes A-D, Los Angeles, CA. U.S. Army Engineer District, San Francisco. (1988). “Humboldt Bay Inspection Report,” San Francisco, CA. . (1996). “Humboldt Bay Inspection Report,” San Francisco, CA. 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uaanjag adUaIaJJIG JO anjeA ajnjosqy Aaaing jevuay Aaaing punois (panunuod) } aqeL (9 $0 9 3004S) (g0'0) 2S't (so’o) 2s"t (zo'0) 190 | (8Z'vEt) 0901+ 02 01 P6912 segesores | (€Z'pe+) 6S'OL+ Zz Olvegi2 | oo Zzsores o9le (00'0) 00°0 (yo'0) 224 (10'0) 060 (49°'22+) Ep'8t 00'80r6912 zesesores | (29:Ze+) ev'8+ 66 Zopegi2 | 96 8ESOPES | siz j P (0922+) by's+ | g90°02P6912 Le‘zesores | (ss22+) op'et Ol ozregl2 | ee cesores v9oL7 (y) wo ‘213-613 (y) wo ‘en-BN (4) w ‘(era) | (en) Burson | (23) Bunseg (4) w ‘(B13) | (6N) Buyyon | (63) Bunsez | ai ryebieL uoneAez uoneAe|y eouele}sIGg Jo enjeA e;Njosqy (papnjauod) Lb a1qe1 Table 2 Aerial ha eT Data Depicting Armor Unit Target Positions (Single-Targeted Armor RS el eee a pi soeonrs [aronear [eoxeceion [si [sowereos [arwoarse [ecuain fe Jesaoies [arooeo [severe [| awenace [amnauae [cones fa fesse [ariowse [seoereser [= | swensen [aamaean [raqnerey [a faneseso [arene [ossrvaian [ee [ewes [awannss [ro(reeo) [a Jesemar [aren [-owoerser |» | smoanan [seameso [retary [a Jasesinse [araten [oorereay [a [sworn [senor [roar [a fesse [arasase [ozovenen [s [soorsie [nemreen [sae [a fesse [arcs [reevansn [= [ewovess [aemaien [saree fe fase [arr [srovaran [ea [esomaas [seria [-eariees) ia Jesse [araoen [osoveray [oe [ewer [aearare [amine ie Jesse [aremsn [eovenan [es [soowaes [meson [rae fr fw ves [onsen [or [worse [ree [ewe 119 soazorz. 34 | 2170845.27 | +5.20 (+17.06) Table 3 Centroid Data and Orientations of Targeted Armor Units (Units with Three Targets) from Aerial Survey farmer unio [essing 00 [Nerhing )__[Eeaton@im@[xeis [Yas [Zam _| for__—(seuiszer[arroooaso |osaoveizsn [20 [ae (| ee fee _[aawierann _[arrionase _[-rancansy [ar | a0 ifm fea _[omimrae [arrionsan | earconsa [<0 | a7 | oa fs —assriesearrcaar[raseteran [wo [na [wor | Ee re foe fetinose [arrcacn [assez | wea [ea | vrro fer _[eateesea _[arricnze _[-aarcarm [ur | «8 | aa fee [emecase[arrieara _[-sencane [ee | ss | wo ice [emsesaar_[arriuare _[-raivaien [os | ve | aa fio fieass [arama [scarey [wo | ae | ma fix [essraoar_[errinsrs _[vaascaoaoy [a7 | «2 | a ive [emiesare_[orrizans _[-aeovaia [oo | 28 | moa ine fewinane [arrorsn | -reaccacy [7 | v9 | so ie oseem [amon [eeu [os | es [a jax _[smossans —[avnaie [oerscaoim | re | «a | 8 jae __[ewionirsn [aves [arowery [ae pwr ava fas __[ewowoas _[areonene _[osenerren [a7 | we -er_ jaw [emowoaas [aveosane _[oranvaniy [as | ve | =o _| jas [eumarave _[areorare [rerovar [ee | eo | -ar_| as [esunerse [aver [screen [02 | a | -ser_| Ea Ee jae —[eworeana _[aveoerse _[rartaa) | s0 [| ex [ma _| fio [asoiarar _[areomeas [ran cane [va | t= [mea | fat _[sionere _[aveemen [oravcasny [ea [es | wa xe _[ooasrsa _[avnenae [naavcnay [02 | ea | -wr_ xe __[emoworso [arose [arrweay [wa | 20d nea eu [esaisose _[areesar [erator | 42 ae [ma _| jas [siownare [avnanan [raavancy [2a | 22 | wos _| Fo ess Jeewo Ihren Iles les eo Table 4 Broken Armor Unit Inventory Data [armor Unit No. | Station No. _| Offset from Baseline m (ft) Type of Break, Comments Pes ee oe Seaside Channelside 714+17 25.30 (83) 71+17 72 + 90 72 +90 73 + 82 73 + 82 74 +00 74 +10 74 +30 74 +30 74+40 Straight mid-shank break 22.86 (75) Straight mid-shank break 18.29 (60) Straight shank-fluke crack 21.95 (72) 14.63 (48) 32.00 (105) 33.53 (110) Straight mid-shank break Straight shank-fluke break Straight mid-shank break Angled mid-shank break 18.29 (60) Straight shank-fluke break 16.76 (55) 21.34 (70) 12.19 (40) Straight fluke-shank break Straight shank-fluke break Straight mid-shank break Straight fluke-shank break Angled mid-shank break = LS) N 4 x & + & 74 + 40 74 +55 74 +65 74 +85 75 +05 75 +10 84 +59 85 + 36 85 + 45 86 + 85 88 + 00 24.38 (80) Straight fluke-shank break = @ 15.24 (50) 18.29 (60) Angled shank-fluke crack 9.14 (30) 20.12 (66) 2.05 (10) Straight fluke-shank break Straight fluke-shank break Straight mid-shank break Straight shank-fluke break = 21.95 (72) 18.29 (60) 18.29 (60) 29.26 (96) 31.09 (102) Angled shank-fluke break (7) Angled fluke-shank crack oS a Angled fluke-shank crack Straight shank-fluke break 25.60 (84) Straight fluke-shank break N 89 + 08 90 + 00 34.75 (114) 36.89 (120) Straight shank-fluke break Oo Straight fluke-shank break 90 + 00 90 + 24 90 + 44 90 + 46 90 + 50 15.24 (50) 33.53 (110) Angled shank-fluke break n = (fo) Angled mid-shank break n = = 31.70 (104) Straight fluke-shank break i?) = ine) 18.29 (60) Straight shank-fluke break QR @ 19.81 (65) 9.14 (30) Straight mid-shank break A B 90 + 70 Straight shank-fluke break 90 + 80 3.05 (10) Straight fluke-shank break 90 + 84 14.02 (46) Straight fluke-shank break $17 100 + 90 0.61 (2) Angled shank-fluke break ‘ a ie Pa lel { ayy 1. ORM TON ay f} NF appa iie, , i . pte wih r phe mabey Ae Ph hs | , on ¥ View Pj i a 1 wri LS = sls ge t uD - Mme A : ut ‘ Mf Vy td ’ eh; WF “a aaa ; Py okiey a pare iets 4 1 Aa — Aa. ai eat ae Le ‘ont ie { f Hy lpecsoupe rence he ae rahe i wl it 7 7 \ ' ‘ ihe * va i : ie Hh hl i As . i i) o Ris bt ae H I Lf sass sf rv Muse as! ; ret tay Yet ew | Ao staan te mae por ae eon AS pul ny rin Rae aernenr ap thie | aml oP end alieanty ‘se unhe eter “oy le 4 ide i en ee he “sane pit Bebe) i ee I va em , yh Psion ‘see a enim 4 ap die tae be! a Ae wer ye ie ie fod ih Bra bi np adel in 8 aN» ot a i Sich UA raion " Uta: (aN Form Approved REPORT DOCUMENTATION PAGE — Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden. to Washington Headquarters Services, Directorate for information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188), Washington, OC 20503. 1. AGENCY USE ONLY (Leave blank) | 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED 5 August 1997 Final report 4. TITLE AND SUBTITLE 5. FUNDING NUMBERS Periodic Inspection of Humboldt Bay Jetties, Eureka, California 6. AUTHOR(S) Robert R. Bottin, Jr., William S. Appleton 8. PERFORMING ORGANIZATION 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) REPORT NUMBER U.S. Anny Engineer Waterways Experiment Station 3909 Halls Ferry Road, Vicksburg, MS 39180-6199 U.S. Amny Engineer District, San Francisco San Francisco, CA 94105-1905 Technical Report CHL-97-17 10. SPONSORING / MONITORING 9. SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) AGENCY REPORT NUMBER U.S. Amny Corps of Engineers, Washington, DC 20314-1000 11. SUPPLEMENTARY NOTES Available from National Technical Information Service, 5285 Port Royal Road, Springfield, VA 22161. 12a. DISTRIBUTION / AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE Approved for public release; distribution is unlimited 13. ABSTRACT (Maximum 200 words) The Humboldt Bay jetties at Eureka, CA, have experienced a long history of damage and subsequent repairs since original construction was completed in 1899. Since dolos rehabilitation of the heads of the jetties in 1971, damages have been primarily along the trunk (stone) reaches of the jetties. No extensive work has been required along the dolos fields since their construction. Pnor to the study documented in this report, no sound, quantifiable data relative to the movement or positions of the dolos concrete armor units had been obtained for the jetties. Data were obtained under the Monitoring Completed Navigation Projects Program from limited ground-based surveys, aerial photography, and photogrammetric analysis to establish very precise base level conditions for the seaward dolos-covered portions of the Humboldt Bay jetties. A method using high-resolution, aerial stereo photographs, a stereoplotter, and Intergraph-based software hasbeen developed to analyze the entire above-water concrete armor unit fields and quantify armor positions and subsequent movement. A detailed broken armor unit survey conducted during the current effort has resulted in a well-documented data set that can be compared to subsequent survey data. This study has defined base conditions and has developed a methodology that can be used to compare subsequent years of high- resolution data for the Humboldt Bay jetties and use these data to assess the long-term response of the structure to its environment. These efforts will allow engineers to decide whether or not closer surveillance and/or repair of the structures might be required to reduce their chances of failing catastrophically. 15. NUMBER OF PAGES HS 48 Dolosse Penodic Inspections 16. PRICE CODE Humboldt Bay, CA Photogrammetry Bee eee || 17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION | 19. SECURITY CLASSIFICATION {| 20. LIMITATION OF ABSTRACT OF REPORT OF THIS PAGE OF ABSTRACT UNCLASSIFIED UNCLASSIFIED NSN 7540-01-280-5500 Standard Form 298 (Rev. 2-89) Prescribed by ANSI Std. 239-18 298-102 14. SUBJECT TERMS Concrete armor units Jetties Remote Sensing ' } Kae fh y a er an “1. | ior = Vis me Ay Gan ca sob sariorelhcarerrtee oro Aw yam Tt Te 2 " hy Tat wane i Ae ov FA AMY i Hoa sas wh on ee a el talk tg to te Ee pe nin ety “earls oh EE RA Ne: _ GRP pail, ange cepreatribnts 2d +e : bieatiay SR UNO any- he i) Meer “a om . yi ly Velma ie andere a ae Dubai fa sean eee aaah be hy aond| Dopeapipee peo LT A ah PTT POD pa. | aC ah akin ree cpg tee ees Seba Sa fa Pry mer bam il pr seri Jeli @atrw ‘ ia adel Mi at ete ved palaey Ors OMY er licenced ane nem Aal aoe a eanccey ETS | q : ee ee EE ash nev (Gs i 7 | nu woe i wry A a3 : ' ‘ t gd { Lt ' PPT AM) pene) ae 2a 1 F 1 ee tw 4 pe ee h r 7 q , , ' i ; f al “ ab > ~ - ye te - ox haw ry » or rere » = “ a i 7 i <7 % adap elie Ww Papel agit Le eer se i & yy nee) (lke? 4 i f A $ 1% : i n i ‘ a3 ; Part ' . T aS < r : 4 A r. M1 Ly as Tea ee 7 i ‘ , 7 « ~<~'" 7 7 aay me \ ~ * hae 190 ay { j fi: i) ce i ) - > rh Le A a t . si ek * jf 4 c TT7) t : Ff i j a : : A . a i ton i ) Sees x far a by Oe 2 ¢ iy cope ee * Spa iic 3 USE weg eadnanensad array Cv Destroy this report when no longer needed. Do not return it to the originator.