Technical Report CHL-97-32 November 1997 US Army Corps of Engineers Waterways Experiment Station Periodic Inspection of Ofu Harbor Breakwater, American Samoa Report 1 Base Conditions by Robert R. Bottin, WES Stanley J. Boc, Pacific Ocean Division Approved For Public Release; Distribution Is Unlimited 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. Berinreo ON RECYCLED PAPER Technical Report CHL-97-32 November 1997 Periodic Inspection of Ofu Harbor Breakwater, American Samoa 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 Stanley J. Boc U.S. Army Engineer Division, Pacific Ocean Building 230 Fort Shafter, HI 96858-5440 Final report Approved for public release; distribution is unlimited mn Vic 0301 0051520 3 Prepared for U.S. Army Corps of Engineers Washington, DC 20314-1000 rar US Army Corps of Engineers VA, Te anaes Waterways Experiment Leo ft \\ TECHNOLOGY Station ¢ aN HEADQUARTERS \ &. - &o HYDRAULICS a vy |S LABORATORY—; =) % pa a a Sore VE Ve \ BS sumone VS a \ YH Snr WS \ a Se Nol ESF COASTAL 8 FOR INFORMATION CONTACT PUBLIC AFFAIRS OFFICE ‘\ RS HET U.S. ARMY ENGINEER ENVIRONMENTAL). TAOS fos SSS BNE YA WATERWAYS EXPERIMENT STATION IM NWN ERR calif CD pH - 3909 HALLS FERRY ROAD ww Yi , fo of VICKSBURG, MISSISSIPPI 39180-6199 PHONE: (601) 634-2502 STRUCTURES LABORATORY SCALE a" AREA OF RESERVATION : 27 sqkm Waterways Experiment Station Cataloging-in-Publication Data Bottin, Robert R. Periodic inspection of Ofu Harbor breakwater, American Samoa. Report 1, Base conditions / by Robert R. Bottin, Jr., Stanley J. Boc ; prepared for U.S. Army Corps of Engineers. 46 p. : ill. ; 28 cm. — (Technical report ; CHL-97-32 rept.1) Includes bibliographic references. 1. Breakwaters — American Samoa — Ofu — Inspection. 2. Harbors — American Samoa —Ofu — Inspection. 3. Sea-walls — American Samoa — Ofu — Inspection. 4. Ofu Island (American Samoa) |. Boc, Stanley J. 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-97-32 rept.1. TA7 W34 no.CHL-97-32 rept.1 Contents [UVSIRIGS ono cess 6 boo. cw ecbd 454 Snag on bo bom dice Gund OID, pola ob clout Vv Conversion Factors, Non-SI to SI Units of Measurement .............-.-- vi NROGMEMOM 5 osce0cccdcocossedaonoo ono oDaKDcaeHC ODODE ODDO OEDRNL 1 Work Unit Objective and Monitoring Approach ..............+++-++--- 1 Project Location and History .......----++++ sees tees eee eee eee 2 Purposes of the Study ...........---- 22s sete eee tte: 12 2—Monitoring Plan and Data ..........------s eee eee eee eee tees 13 /Nmnor Wintkt SURIGYP soc cecoasse cco cdocc soon Boones doco usocODRaESS 13 Targeting and Ground Surveys ...........+- 2-200 e eee e seer ee eeeees 14 (Acnalehotocraphymeaen ier eerie eer ttre 21 Photogrammetric Analysis of Armor Unit Targets .........-----++++-- 22 Be SUMMTBIAY oo conccc gobs sooosnsesooneasconKsasuE GOED ODDEBOO DEE 26 IRGUSTINGS odcoadcuocovepooooovcdc su sasddnapano0odoDo Dada bOdCIWCC 28 Tables 1-5 SF 298 List of Figures — ee Figure 1. Location of American Samoan Islands ..........---+-+++-+++-- 3 Figure 2. Location of Ofu Harbor ...........- +2. sees eee eens 4 Figure 3. Original layout of Ofu Harbor, American Samoa .......-..-.-- 5 Figure 4. Layout of harbor after 1994 rehabilitation ............---+--- 7 Figure 5. | Tribar armor units used on Ofu Harbor breakwater ..........-- 8 Figure 6. Concrete rib cap on crest of Ofu Harbor breakwater ..........-- 8 Figure 7. View of 1,635-kg (1.8-ton) “swiss cheese block” concrete INGerlaVerUNIt ener eee tae eel ea 9 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. 2,270-kg (2.5-ton) high-strength concrete units used on harbor GCEOORAMUGTIIE ooccasocccogacpo0a000000000000000000008 Typical cross sections for 1994 breakwater construction ....... Aerial photograph of Ofu Harbor breakwater (1996) .......... Separation between tribar and rib cap .........-...--.------ Separation between “swiss cheese block” underlayer units ..... Spalling of 510-kg (1,125-Ib) high-strength concrete uNGderlayenMUnitsee see etree eee cee ee eet er eee Diagram of monuments and survey control points used at Of Harborin cost ee reer roe eres sneeorsiecch alee at View of a targeted tribar (three targets established) ........... Location of targeted armor units on outer portion of breakwater immer eee re ce era rere rence) rer teen: Location of targeted armor units on inner portion of breakwalce nen nen Ornne noes icc recite ra Representative targeted armor unit positions relative to x, Wo ING) 74 ABIOS.n ca ooccososnooboovooNE OHNO E MDE Ds GOC0006 Aerial view of breakwater looking shoreward...............- Aerial view of breawater looking seaward ...........-.----- Preface The study reported herein was conducted as part of the Monitoring Com- pleted 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 accomp- lished by the Hydraulic Design Section of Headquarters, U.S. Army Corps of Engineers (HQUSACE). The Coastal and Hydraulics Laboratory (CHL), U.S. Army Engineer Waterways Experiment Station (WES), is responsible for technical and data management support for HOUSACE review and technology transfer. Technical Monitors for the MCNP Program are Messrs. John H. Lock- ‘hart, Jr., Barry W. Holliday, and Charles B. Chesnutt (HQUSACE). The Pro- gram 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 Ofu Harbor breakwater, American Samoa, to its environment. The information contained in this report was gathered as a result of land and aerial survey work conducted by Richard B. Davis, Inc., under contract to the Corps of Engineers, and an armor unit survey conducted by Messrs. Robert R. Bottin, Jr., and George F. Turk (CHL), and Mr. Stanley J. Boc, U.S. Army Engineer Division, Pacific Ocean (CEPOD). The work was conducted during the period October 1996 through June 1997 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. Markle, Chief, Wave Processes Branch. This report was prepared by Messrs. Bottin, CHL, and Boc, CEPOD. Director of WES during the investiga- tion and publication of this report was Dr. Robert W. Whalin. Commander and Deputy Director was COL Robin R. Cababa, 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 Units of Measurement Non-SI units of measurement used in figures, plates, and tables of this report can be converted to SI units as follows: iles (U.S. ) tons (2,000 pounds, mass 907.1847 Chapter 1 1 Introduction Work Unit Objective and Monitoring Approach The objective of the Periodic Inspections work unit in the Monitoring Com- pleted 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 mainte- nance of both existing 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 provided, 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 structure at periodic intervals using high-resolution aerial photography. Periodic aerial photographs are compared visually to gauge the degree of in-depth analy- sis 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 documenta- tion of major storms occurring in the locality are presented along with the moni- toring 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 struc- ture geometry can be defined at a point in time. By direct comparison of photo- graphs 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 determine if structure changes are occurring that indi- cate possible failure modes and the need to monitor the structure(s) more closely. The Ofu Harbor breakwater, American Samoa, was nominated for periodic monitoring by the U.S. Army Engineer Division, Pacific Ocean (CEPOD). Three additional CEPOD projects have been monitored previously under the Periodic Inspections work unit. Base conditions have been defined for break- waters at Kahului Harbor, Maui, HI; Laupahoehoe Boat Launching Facility, Hawaii, HI, (Markle and Boc 1994); and Nawiliwili Harbor, Kauai, HI (Bottin and Boc 1996). Project Location and History American Samoa is a group of seven islands (five volcanic islands and two coral atolls) located in the South Pacific Ocean. These islands lie at approxi- mately 170 deg west longitude and 14 deg south latitude and comprise a total area of about 200 sq km (76 sq miles).' They are located about 6,700 km (4,150 miles) southwest of San Francisco, California, and about 3,700 km (2,300 miles) south-southwest of Hawaii (Figure 1). The five major inhabited islands of America Samoa are Tutuila, Aunuu, Ofu, Olosega, and Tau. Tutuila, the largest and principal island, is the center of gov- ernment and business. Aunuu lies 1.6 km (1 mile) off the east coast of Tutuila. The three islands (Ofu, Olosega, and Tau) are collectively referred to as the Manu'a Islands and are located 106 km (66 miles) east of Tutuila. Ofu and Olosega are often called sister islands because they are separated by less than 275 m (900 ft) of shallow reef. The American Samoan Islands were discovered in the 1700's by Dutch navi- gators. However, the islands remained unclaimed until the 1900's, when the chiefs of the islands ceded title to the United States (CEPOD 1973). The U.S. Navy administered the islands as a U.S. territory until 1951, when the U.S. Department of the Interior assumed administration. Its inhabitants are American nationals, but not citizens. They may visit or emigrate to the United States without passport. 1 Units of measurement in the text of this report are shown in SI units, followed by non-SI units in parentheses. In addition, a table of factors for converting non-SI units of measurement used in figures in this report to SI units is presented on page vi. Chapter 1 Introduction OSSIONVYS NYS 0002 SATA NI ATVOS alaadVd 0 9 fo) IVMVH 2° spue|s| Ueowes Ueda Jo UO}e007 *} aunbi4 : NOILVWIOT LOFT Od SIAVL oar of Sl vinini ‘S| V935SO10 ‘SI NANAY (YOWYVS “M) 'SiN4O So “SI N70an CES “SINAYS SGNV1SI VOWVS DIsIDVd HLNOS WYND o Nwdivs ~ woo WIINVN AWANIDVd Introduction Chapter 1 The island of Ofu has an area of about 4.8 sq km (3 sq miles). It is of vol- canic origin and is encircled by a fringing reef. The reef generally ranges from 300 to 600 m (1,000 to 2,000 ft) in width, with depths varying from 0.3 to 1.8 m (1 to 6 ft).’ Ofu Harbor is situated on a reef platform off the northwest coast of the island (Figure 2). The project, constructed in 1975, utilized a portion of an existing natural channel through the reef. It consisted of a 5.5-m-deep (18-ft- deep), 40-m-wide (130-ft-wide) entrance channel approximately 67 m (220 ft) in length and a 4.9-m-deep (16-ft-deep) turning basin with horizontal dimensions of approximately 91 x 91 m (300 x 300 ft). Material from channel and turning basin dredging was used to construct a 12,140-sq-m (3-acre) landfill adjacent to mooring areas and for protection of the harbor from wave action (CEPOD 1973). The landfill, where exposed to wave action, was armored with a stone revetment. The revetment was placed on a slope of 1V:1.5H and consisted of armor stones ranging from 910 to 1,815 kg (1 to 2 tons) and underlayer stone ranging from 450 to 910 kg (0.5 to 1 ton). Figure 3 is a plan view of the originally constructed breakwater. TAUSA POINT OFU HARBOR NUUTELE TUAFANUAI ISLAND Q {SLAND OF OFU PACIFIC OCEAN SCALE IN FEET Figure 2. Location of Ofu Harbor In 1981, the Ofu Harbor revetment was severely damaged by tropical storm Esau, with subsequent repairs completed in 1982. Then in 1990, Hurricane Ofa struck American Samoa and the revetment again sustained severe damage. Before the structure could be rehabilitated, Cyclone Val further damaged it in 1991. The revetment was almost completely destroyed. Armoring and under- layer stone on both the harbor and sea sides required complete repair. The ' All elevations and depths cited herein are in meters (feet) referred to mean low water (mlw) datum. Chapter 1 Introduction INITZYOHS INILSIXF (MIW) dSLYM MOT NVAW OL G3YY34d5Y L344 NI NMOHS 4YV SNOILVA314 Bowles UDA “JOQIEH MO JO InoAe) jeulBUO ‘¢€ eunbi4 1334 NI 31VOS -AFIY TVWYOD TANNVHO FONVYLNG Oih= MSW ONINENL NYVIIO DFIVd OL+ THAIGNV? 4FIIY 1VYOD Introduction Chapter 1 entrance channel and turning basin also required dredging to remove stone and dredged landfill material washed into the harbor. The latest rehabilitation was completed in 1994 and consisted of construction of a new breakwater that extended from sta 1+75 to sta 6+00, as shown in Fig- ure 4. The breakwater was moved back 15.2 m (50 ft) shoreward of the reef in order to provide the incoming wave more area between the reef and the structure in which to break and dissipate its energy. All loose material seaward of the new structure also was removed. The breakwater cross section was modeled at the U.S. Army Engineer Waterways Experiment Station (WES) for hydraulic stability (Turk 1995). For environmental, economic, and logistical reasons, additional basalt stone material could not be obtained from either Ofu Island or Tutuila Island to con- struct the Ofu Harbor breakwater. Only the stone at the project site that could be salvaged was available for use in breakwater construction. The structure, there- fore, was built utilizing a unique “concrete design.” Basically, the design entailed using various sized concrete units for breakwater construction as opposed to using basalt stone. The breakwater armor consisted of a single layer of uniformly placed 4,080-kg (4.5-ton) concrete tribar units (Figure 5). The tribars originated at sta 1+75 on the seaward face of the structure and extended to sta 6+00, around the head, and then to sta 4+00 on the harbor side of the breakwater. To improve the stability of the tribars, work included the construction of a toe trench in order to stabilize the armor unit toe, and a concrete rib cap system on the breakwater crest to stabilize and buttress tribars at the upper sea-side and harbor-side slopes. The rib cap forms were fabricated and concrete poured right into the top section of the tribars (Figure 6). The crest elevation of the rib cap was +4.6 m (+15 ft), and the slope of the structure was 1V:1.5H. Due to the non-availability of local stone as mentioned earlier, concrete underlayer units were used during construction of the Ofu Harbor breakwater. A unique 1,635-kg (1.8-ton) concrete unit, designed and developed by CEPOD, was used as an underlayer for the tribars on the trunk section of the breakwater. These units are approximately 1.2 x 1.2 x 0.6 m (4.0 x 4.0 x 2.0 ft) in size with chamfered corners. They have 0.4-m- (16-in.-) diameter holes in their centers with 0.23-m- (9-in.-) diameter semicircular holes on each side protruding through the units from front to back. When placed in a one-layer section on the breakwater slope, the holes create void spaces in which wave energy can be dissipated. The underlayer unit, with the holes, resembles a slice of swiss cheese and has been labeled the “swiss cheese block.” Figure 7 is a view of the unit. In addition to the “swiss cheese block” underlayer unit, both 2,270-kg and 510-kg (2.5-ton and 1,125-Ib) concrete units were formed by pumping high- strength, fine-aggregate concrete into geotextile fabric bags. The 2,270-kg (2.5-ton) units were used as a rib cap underlayer and were placed along the land- fill on the harbor side of the structure between stas 1+75 and 4+00 (Figure 8). These units measured approximately 1.4 x 0.9 x 0.8 m (4.5 x 3.0 x 2.5 ft) in size. Chapter 1 Introduction Oct 08 as 1334 NI 31VOS 4FIY 1VYOD 9L- NISVE ININENL AINITFYOHS ONILSIXS t I ' \ ‘ ' i] U \ ' i ' \ 1 ! | U | 1 ' | L OL + TIHAGNVI (MAW) HSLVM MO1 NVAW OL Ga4H343Y4 1334 NI NMOHS 3Yv SNOILVAS14 ‘ALON UOHeWIGeUues EE} 4eye JoqueU Jo jnoAeT ‘yp SunBi4 TANNVHO JFINVYLNI 44dY 1VYOO NVd9I0 JswlIVd Nw Introduction Chapter 1 Figure 6. Concrete rib cap on crest of Ofu Harbor breakwater The 510-kg (1,125-Ib) concrete units were used as an underlayer for the 2,270-kg (2.5-ton) units. They also were used as an underlayer for the tribars around the breakwater head since the 1,635-kg (1.8-ton) “swiss cheese blocks” could not be placed in this area around the relatively tight radius. The dimensions of the Chapter 1 Introduction Figure 7. View of 1,635-kg (1.8-ton) “swiss cheese block” concrete underlayer unit Figure 8. 2,270-kg (2.5-ton) high-strength concrete units used on harbor side of structure 510-kg (1,125-Ib) concrete units were about 0.9 x 0.6 x 0.3 m (3.0 x 2.0 x 1.0 ft). Typical cross sections of the 1994 breakwater construction are presented in Fig- ure 9. An aerial view of the harbor breakwater is shown in Figure 10. Chapter 1 Introduction HARBOR SIDE SEA SIDE 2.5 TON HIGI! STRENGTH CONCRETE UNITS (FORMED IN GEOTEXTII_E BAGS) mM 1,125 LB HIGH STRENGTH} CONCRETE UNITS (FORMED IN GEOTEXTILE BAGS) SINGLE LAYER 4.5-TON TRIBAR UNIFORMLY PLACED LANDFILL EL + 107 SINGLE LAYER 1.8 TON CONCRETE UNDERLAYER UNITS (CHEESE BLOCKS) NEW AND SALVAGED 200 TO 400 LB UNDERLAYER STONE, 2 STONES THICK ed Aa @ EXSTING CORAL REEF VARIES —— 1 TO 100 L.B BEDDING STONE, 18" THICK STA 1475 TO 4+00 HARBOR SIDE SEA SIDE SINGLE LAYER 4.5.TON TRIBAR : UNIFORMLY PLACED = CONCRETE RIB CAP 2.5 TON HIGH STRENGTH CONCRETE oe UNITS (FORMED IN GFOTEXTILE BAGS) 1,125 1B HIGH STRENGTH CONCRETE SINGLE LAYER 4.5-TON TRIBAR UNITS (FORMED IN GEOTEXTILE BAGS) : UNIFORMLY PLACED SINGLE LAYER 1.8 TON CONCRETE UNDERLAYER UNITS (CHEESE BLOCKS) NEW AND SALVAGED 200 TO 400 LB UNDERLAYER STONE, 2? STONES THICK 1 TO 100 LB BEDDING STONE 18° THICK STA 4+00 TO 6+00 HARBOR S:!DE SEA SIDE SRETE RIB CAP SINGLE LAYER 4.5-TON TRIBAR CONcR El UNIFORMLY PLACED =— 2.5 TON HIGH STRENGTH CONCRETE SINGLE LAYER 4.5-TON TRIBAR UNITS (FORMED IN GEOTEXTILE BAGS) 15 UNIFORMLY PLACED |; — 1,125 LB HIGH STRENGTH CONCRETE UNITS (FORMED IN GEOTEXTILE BAGS) NEW AND SALVAGED 200 TO 400 LB UNDERLAYER STONE, 2 STONES THICK 1 TO 100 LB BEDDING STONE, 18” THICK STA 6 +00 (HARBOR SIDE) AROUND HEAD TO STA 6 +00 (SEA SIDE) Figure 9. Typical cross sections for 1994 breakwater construction 10 Chapter 1 Introduction (9661) seremyessg JOGIEH NJO Jo udesHojoud jeuey -O| aunBig = = - = xe) = oO 3 a) fe) a=) = Chapter 1 12 Purposes of the Study The 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 armor units on the Ofu Harbor breakwater. Conduct land surveys, armor unit inspections, aerial photography, and photogrammetric analyses to: (1) Test and improve developed methodologies and accurately define armor unit movement above the waterline. (2) Establish base conditions for the breakwater's armor units which can be revisited in the future under the Periodic Inspections work unit. Chapter 1 Introduction 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 Ofu Harbor breakwater could be defined through periodic inspections. The con- crete armor units on the outer 130-m-long (425-ft-long) portion of the breakwater were monitored. The monitoring plan consisted of targeting and ground surveys, aerial photography, photogrammetric analysis of armor units above the water- line, and ground-based broken armor unit surveys. Armor Unit Survey On 16 October 1996, a walking survey of armor units above the waterline was conducted on the outer 130-m (425-ft) portion of the Ofu Harbor break- water. The survey of the structure revealed no broken tribars. One sea-side tribar was slightly separated from the rib cap (Figure 11) at sta 3+05. On the Figure 11. Separation between tribar and rib cap Chapter 2 Monitoring Plan and Data 13 14 sea side of the structure it also was noted that some of the “swiss cheese block” underlayer units had separated along the slope (approximately sta 4+50). One separation was about 20 cm (8 in.) as shown in Figure 12, with a few others about 10 cm (4 in.). It appeared that the separations were caused due to the lower underlayer units subsiding on their bottom ends. The geotextile bags had deteriorated and some spalling along the edges of the 510-kg (1,125-Ib) high- strength concrete underlayer units was also noted around the head of the struc- ture (Figure 13). In general, the breakwater appeared to be in excellent condition. Figure 12. Separation between “swiss cheese block” underlayer units Targeting and Ground Surveys Points were required to serve as control (both horizontal and vertical refer- ence) for the ground-based survey work as well as the photogrammetric work on the breakwater. Ground surveys were initiated from known Corps of Engineers monuments, which included stations CBM3, X, RAMP, and CAMBRA. An additional monument (brass disk) designated “TOM” was cemented into the con- crete cap of the breakwater. Also, 16 additional control points (designated 2 through 17) were established on the cap of the breakwater. These were estab- lished by painting a black target. A 0.64-cm (1/4-in.) hole was drilled at the center of each target for identification in subsequent surveys. The additional monument and control points were established using global positioning system control surveying and electronic land surveying techniques. Positions and eleva- tions of the monuments and control points established on the structure are presented below. Their approximate locations are shown in Figure 14. Chapter 2 Monitoring Plan and Data Figure 13. Spalling of 510-kg (1,125-Ib) high-strength concrete underlayer units Pesstng [Nerhing TER 347,719.44 347,804.89 347,595.99 613,025.90 347,707.09 OM 613,174.65 348,117.59 Points on Breakwater Cap +4.849 (+15.91) +1.1960 (+6.43) +0.850 (+2.79) +4.575 (+15.01) +4.590 (+15.06) CBM3 613,675.37 613,448.05 613,624.40 o|p|~x ° >|> ° 2|= 3 as 3 > 0 9. a3 + = 613,309.07 348,164.91 +4.389 (+14.40) 613,275.34 348,151.90 +4.913 (+16.12) 613,240.61 348,141.61 +4.417 (+14.49) 613,151.07 +4.542 (+14.90) .95) ) ) (2) ( 613,102.11 347,909.39 +4.557 (+14.95 613,089.91 347,875.56 +4.563 (+14.97) 613,077.54 347,841.68 +4.581 (+15.03 613,065.28 347,807.88 +4.563 (+14.97 613,053.06 347,773.98 +4.557 (+14.95) 613,040.74 347,740.12 +4.538 (+14.89 13 ay }) as |] a]fa Oya; yo] 17 Chapter 2 Monitoring Plan and Data 15 LEGEND © MONUMENT @ SURVEY CONTROL POINT HO wos) | ‘CAMBRA Figure 14. Diagram of monuments and survey control points used at Ofu Harbor 1 6 Chapter 2 Monitoring Plan and Data Horizontal positions are based on the American Samoa Plane Coordinate System and all elevations are referenced to mlw datum. The initial ground survey work was conducted during the period 17-18 October 1996. A total of 33 tribars were selected for detailed study. They represent an even distribution throughout the tribar field, and occupy positions ranging from near the waterline to close to the rib cap at the crest of the structure. These armor units (tribars 101-133) were painted with three targets (Figure 15). The target number is followed by an A, B, or C. Three targets on an individual tribar allow for very precise measurements depicting individual armor unit movement. Twenty additional tribars (units 19-38) were painted with a single target to serve as photogrammetric control points, as well as to be used to detect armor unit movement during future ground surveys. A 0.64-cm (1/4-in.) hole was drilled at the center of each target to mark the survey points for subsequent surveys. Loca- tions of the targeted tribars are shown in Figures 16 and 17. Positions and eleva- tions of the targeted tribars obtained during the October 1996 survey are pre- sented in Table 1. Figure 15. View of a targeted tribar (three targets established) For the tribars with three targets, a more in-depth analysis was conducted. With the x, y, and z (easting, northing, and el) coordinates defined for each tar- get on the various armor units, the centroid of each targeted tribar was computed. In addition, the position of each armor unit relative to the x, y, and z axes was determined. Figure 18 shows the orientation of representative tribars to the three axes. The centroid of each targeted tribar and each armor unit's orientation (rota- tion angle relative to x, y, and z) are presented in Table 2. Computations were made based on the October 1996 ground survey. These are base level conditions from which comparisons can be made in future surveys. Chapter 2 Monitoring Plan and Data 17 Jeyemyesq }O UOILOd Ja}nNo UO sylUN JOWJe peje6Je} Jo UOeD07 “9 aunbi4 LA9DYVL FIONIS HLIM YVEINL =@ SLAOYVL FTdILINW HLIM YVEIYL 4 Chapter 2 Monitoring Plan and Data Jayemyeesq JO UOIOd JeuU! UO s}luN JoWWe pajebie] Jo UONeD07 “Z| eunBi4 LADUVL FTONIS HLIM YValdl @ SIFOUVL FIGILINW HLIM MVEIulL & 9 1 Chapter 2 Monitoring Plan and Data CLL YVEIYL Sexe Z pure ‘A ‘x 0} SAijeja4 SuO!ISOd jun JoWWe pejebie] eAlejuasaiday -g|. eunbi4 EOL YVEIYL Chapter 2 Monitoring Plan and Data 20 As discussed in the next section of this report, logistical problems were encountered during attempts to obtain aerial photography. Additional ground survey data were obtained on two occasions while attempting to secure aerial survey data. These data were obtained on 16 March and 7 June 1997. Positions and elevations of representative targets obtained during the March 1997 survey are shown in Table 3. The absolute values of differences in posi- tions and elevations between the March 1997 and the October 1996 survey also are presented in Table 3. Differences between the values ranged from 0.0 to 11.0 cm (0.0 to 0.36 ft) in the horizontal direction and from 0.3 to 7.0 cm (0.1 to 0.23 ft) in the vertical direction. The average of the differences in the x, y, and z directions was 1.4, 1.2, and 1.2 cm (0.047, 0.038, and 0.040 ft), respectively. Based on the surveys, 75 percent of the targets moved less than 1.5 cm (0.05 ft) in the horizontal direction, and 75 percent of the targets moved less than 1.5 cm (0.05 ft) in the vertical direction. Position and elevation data obtained for the tribar targets during the June 1997 survey are presented in Table 4 as well as the absolute values of the differ- ences in positions and elevations between this and the October 1996 survey. Differences between the values ranged from 0.0 to 14.6 cm (0.0 to 0.48 ft) horizontally and from 0.0 to 11.6 cm (0.0 to 0.38 ft) vertically. The average of the differences in the x, y, and z directions was 1.3, 1.5, and 0.9 cm (0.043, 0.048, and 0.029 ft), respectively. Of the targeted points, 73 percent moved less than 1.5 cm (0.05 ft) horizontally, and 90 percent moved less than 1.5 cm (0.05 ft) vertically based on the survey results. Forty targets were surveyed during March 1997, and 94 targets were surveyed during the June 1997 deployment. Based on the survey results, tribar 113 (located on the breakwater head) had the greatest horizontal movement, and tribar 127 (on the breakwater trunk) had moved the greatest vertical distance. With the exception of these two tribars, only four additional ones (tribars 114, 118, 130, and 133) had moved more than 3 cm (0.1 ft) in any direction (horizon- tal or vertical). 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. A manned, propane-powered, blimp/balloon-type aircraft was proposed to obtain aerial photography for the remote Ofu Harbor breakwater, since no per- manent aircraft are based on the island. The equipment was shipped to Pago Pago, Tutuila, and then to Ofu Harbor aboard the open deck of a World War II landing craft. Shipping the equipment proved to be extremely difficult, as new Federal Aviation Administration regulations regarding shipping of gas containers or gasoline-powered engines were very stringent. Both the propane tanks and Chapter 2 Monitoring Plan and Data 21 22 gas tanks had to be purged and certified as empty prior to shipment to Pago Pago. The balloon's gas tanks were to be filled with propane in Pago Pago and shipped on the barge to Ofu. When they arrived, however, it was found that they had been filled with low-pressure butane. At this point it was determined that propane was not available in American Samoa, and that the terms propane and butane were used interchangeably. Because of the pressure differences, butane could not be used in the balloon. Strong winds and heavy rain contributed to delay of the balloon flight, but the discovery of the improper fuel canceled the low-altitude balloon flight entirely. In an attempt to complete the mission, a twin-engine otter aircraft was chartered from Samoa Air. The baggage door was removed, and an oblique mount was constructed to allow the mapping camera to be placed in the opening. The oblique photography that was obtained provided visual imagery of the struc- ture and the harbor. At some point, the camera began malfunctioning, plus the speed of the aircraft at the low altitude and the very rough air caused by the vertical rise of the adjacent mountain, prevented the collection of a series of high-quality exposures. Figures 19 and 20 are aerial photos of the breakwater looking shoreward and seaward, respectively. The aerial photography was obtained on 20 October 1996. In an attempt to obtain improved imagery for higher accuracy photogrammet- ric measurement purposes, arrangements were later made to charter a helicopter and again photograph the structure. The helicopter was based on a tuna clipper operating out of Pago Pago. While the contractor was enroute to American Samoa in March 1997 to complete the work, the helicopter left aboard its mother ship for the fishing grounds and was not available. The only other helicopter located was inoperative. As mentioned earlier, a ground survey of representative targets was completed. In a final attempt to obtain low-altitude aerial photography, the contractor again arranged to charter a helicopter based on one of the tuna clippers in Pago Pago. The helicopter arrived on Ofu as scheduled, on 7 June 1997. The aircraft, however, had encountered very strong headwinds on the flight and used more fuel than estimated. No fuel is available on Ofu. Because of fuel considerations and the weight of the mapping camera equipment, the pilot would not allow the heavy mapping camera in the helicopter and limited his flight time on the island to 30 min. A backup 70-mm hand-held aerial camera was used to obtain views of the jetty from the open doorway of the aircraft, but due to damage in ship- ment, exposures were unacceptable for high-accuracy photogrammetric measure- ments. Additional ground-based surveys were conducted during this deployment. Photogrammetric Analysis of Armor Unit Targets When aerial photography is planned and conducted so that each photo image overlaps the next by 60 percent or more, the two photographs comprising the Chapter 2 Monitoring Plan and Data 2 By hm, RAAF a4 ¢ AG BERR ERD EERE ERROR ERG GREER eee eresreeerss PUERPUPEUEERERDULI Li etiteiiiin aoe 4S Ah th Figure 19. Aerial view of breakwater looking shoreward 23 Chapter 2 Monitoring Plan and Data TTTTTDPSPPa aa PPLE ERE EE EE Figure 20. Aerial view of breakwater looking seaward Chapter 2 Monitoring Plan and Data 24 overlap 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 over- lapping photography, very accurate measurements of any point appearing in the photographs can be obtained. This technique is called photogrammetry. Due to logistical problems mentioned previously, low-altitude, high-quality, stereo pair images were not obtained for the Ofu Harbor breakwater. The aerial photographs obtained from the fixed-wing aircraft during the October 1996 deployment, however, were analyzed in an analytical stereoplotter using conver- gent photogrammetric techniques. These procedures produce results that are not as precise as the vertical stereo pair analysis, but provided acceptable and useful data. The oblique images were oriented to control point data in the stereo model, where measurements could be obtained for the targeted tribars. The stereo model was used for all photogrammetric compilation. A photogrammetric analysis of the armor unit targets was conducted and x, y, and z (easting, northing, and el) coordinates were obtained. These data were compared to those obtained during the October 1996 ground surveys to establish the accuracy of the photogrammetric work. Position and elevation data obtained for the tribar targets as a result of the photogrammetric analysis are presented in Table 5. In addition, the absolute values of the differences in position and eleva- tion as opposed to the ground survey are also shown in Table 5. Differences between the values ranged from 0.0 to 12.2 cm (0.0 to 0.4 ft) in the horizontal directions and from 0.0 to 10.1 cm (0.0 to 0.33 ft) in the vertical direction. The average of the differences between the x, y, and z coordinates was 3.3, 4.1, and 2.3 cm (0.108, 0.134, and 0.077 ft), respectively. Differences in the vertical positions were closer than the horizontal positions. Based on the analysis, only 22 percent of the target differences were less than 1.5 cm (0.05 ft) in the horizon- tal directions, and 35 percent of the differences in the vertical direction were less than 1.5 cm (0.05 ft). Of all horizontal positions, 51 percent were within 3 cm (0.1 ft), as were 77 percent of all vertical positions. Full-scale hard copies of aerial photographs are on file at the authors' offices at WES and CEPOD. In addition, all photogrammetric compilations and analy- ses have been stored on diskettes in Intergraph files for future use. In summary, detailed information relative to the armor unit positions for the Ofu Harbor breakwater have been captured by means of aerial photography and photogram- metric analysis. Data are stored and can be retrieved and compared against data obtained during subsequent monitoring. Thus, armor unit movement may con- tinue to be quantified in future years. Chapter 2 Monitoring Plan and Data 25 26 3 Summary Ofu Harbor is subjected to severe storm conditions in the South Pacific, including tropical storms, hurricanes, and cyclones. The original revetment and mole used for harbor protection was damaged several times, and in 1991, was almost completely destroyed. As a result, a new breakwater was constructed in 1994 which included the use of 4,080-kg (4.5-ton) concrete tribar armor units. Various concrete underlayer units were also used in the structure, since local stone was not available. No sound, quantifiable data relative to the movement or positions of the concrete armor units had been obtained for the structure prior to this study. Under the current Periodic Inspections work unit of the Monitoring Com- pleted Navigation Projects Program, data from limited ground-based surveys, aerial photography, and photogrammetric analysis were obtained to establish base level conditions for the Ofu Harbor breakwater. Logistical problems were encountered attempting to obtain low-altitude aerial photography in this remote location. The planned low-altitude photography was not obtained; however, oblique images taken from a fixed-wing aircraft were analyzed using convergent photogrammetric techniques, which proved to be acceptable. 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 structure. The procedure utilized the oblique images, a stereoplotter, and Intergraph-based software to analyze the entire above-water armor field and quantify armor positions. A detailed walking survey of the structure conducted during the effort resulted in a well-documented data set that can be compared to subsequent surveys. Now that base (control) conditions have been defined at a point in time and a methodology has been developed to closely compare subsequent years of data for the Ofu Harbor breakwater, 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 structure might be required to reduce its chances of failing catastrophically. Also, the periodic inspection methods developed and validated for this structure may be used to gain insight into other Corps structures. Chapter 3 Summary Numerous logistical problems were encountered while attempting to obtain aerial photography at this remote South Pacific Island site. For future surveys of the structure, ground surveys and walking inspections are recommended. Aerial photography and photogrammetric analysis are not recommended for future surveys at Ofu Harbor breakwater without strong economic justification. Chapter 3 Summary 27 28 References Bottin, R. R., Jr., and Boc, S. J. (1996). “Periodic inspection of Nawiliwili Harbor breakwater, Kauai, Hawaii; Report 1, Base conditions,” Technical Report CERC-96-5, U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS. Markle, D. G., and Boc, S. J. (1994). “Periodic inspections of Kahului and Laupahoehoe breakwaters, Hawaii; Report 1, Base conditions,” Technical Report CERC-94-12, U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS. Turk, G. F. (1995). “Ofu Harbor, American Samoa, breakwater 2-D hydraulic stability test,” Technical Report CERC-95-16, U.S. Army Engineer Water- ways Experiment Station, Vicksburg, MS. U.S. Army Engineer Division, Pacific Ocean. (1973). “Detailed project report, Ofu Harbor for light-draft vessels, Ofu Island, American Samoa,” Honolulu, HI. References Table 1 Ground Survey Data Depicting Armor Unit Target Positions as Result of October 1996 Surve Easting (x) | Northing (y)_ | El (2), m (ft) Target ID | Easting (x) 613107.74 | 347804.38 | 44.81 (+15.77) 117B 613041.32 347800.32 | +2.84 (+9.33) 101B 6131114 347895.43 | 44.11 (413.48) 1176 |.613042.88 347804.41 101C 613110.01 | 34789116 [44.13 (+1355) | 118A 613046.89 347820.84 | +2.46 (+8.06) 102A 613103.26 | 34786877 __| +3.80 (+12.47) 118B 613045.52 347816.55 | +2.51 (+8.22) 1028 613104.75 | 347873 43.81 (412.49) | 118C 613043.27 347819.61__| +1.79 (+5.86 1026 613107.08 | 347869.79 43.15 (+10.34) (| 119A 613064.14 347836.1 | +4.76 (+15.61) 103A 613105.85 | 34785214 | +2.19 (+7.20)_ 1198 613060.36 347835.45 | 44.02 (+13.20) 103B 613109.55 | 347853.84 | 44.61 (+5.28) 149 613062.24 | 347839.48 | +4.04 (+13.25) 103C 613108.68 | 347849.41 | 41.50 (+4.93) 120A 613067.77 347863.49 | 43.46 (+11.35) 104A 613084.23 | 347833.27 __| +4.98 (+16.35) 120B 613064.01 347862.63 | +2.78 (+9.11) 104B 613084.88 | 347837.61 _| +5.05 (+16.56) 1206 613065.75 347866.77 _| +2.82 (+9.24) 104C 613087.81 | 347835.12 _| +4.39 (+14.41) 121A 613066.47 347878.44 | +2.18 (+7.15) 105A 61308353 | 347813.74 _| +3.84 (+12.61) 121B 613062.79 347877.47 _| +1.49 (+4.89) 105B 613085.7 347817.62 _| 43.67 (+12.04) 121C 613064.21 347881.63 | +1.50 (+4.92) 105C 613087.32 | 347813.9 +3.13 (410.27) 122A 613086 347896.88 | +4.88 (+16.00) 106A 613086.29 | 347797.3 42.22 (+7.27) 1228 613082.38 347896.55 | +4.06 (+13.31 106B 613089.91 | 347798.84 | 41.58 (45.18) ‘| 122C 613084.41 347900.57 106C 61308879 | 347794.57 | +1.51 (+4.94) 123A 613088.02 347919.35 | +3.39 (+11.13 107A 613066.96 | 347781.4 +4.69 (415.38) 1238 613084.25 347918.61__ | +2.73 (+8.97) 107B 61307043 | 347783.21 | +4.15 (+13.63) 123C 613086.04 34792275 _ | +2.76 (+9.06) 1076 613069.84 | 347778.84 _| +4.06 (+13.33) 124A 613091.01 | 347947.15 _| +2.00 (46.56) 108A 613064.21 | 347754.79 _| 43.47 (+11.37) 124B 613087.21 347946.26 | 41.38 (+4.52) 108B 613068.01 | 347756 42.84.(49.31) __|124C 613088.74 347950.39 | +1.35 (+4.44) 108C 613066.63 | 347751.75 _| +2.83 (+9.27) 125A 613110.12 347965.44 109A 613064.13 | 347735.66 _| +2.23 (+7.30) 125B 613106.54 347964.85 | +3.87 (+12.69) 1098 613067.87 | 347736.64 __| +1.55 (+5.09) 125C 613108.5 347968.91 _| +3.96 (+12.98) 109C 613066.47 | 347732.46 _| +1.56 (+5.12) 126A 613111.12 347986.98 | +3.40 (+11.14) 110A 613041.6 34772155 |+5.12(+16.79) | 1268 613107.38 | 347986.79 _| +2.69 (+8.82) 110B 613045.58 | 347722.1 44.54 (414.89) 126C 613109.53 347990.72 _| +2.84 (+9.33) 410C 613043.8 347718.01 | +4.61 (+15.12) 127A 613110.24 348002.66 44 (47. 114A 613043.67 | 347701.78 _| +3.58 (+11.76) 127B 613106.62 348002.37 _ | +1.41 (+4.61) 111B 613047.44 | 34770058 _| +3.00 (+9.83) 127C 613108.6 348006.37 _ | +1.52 (+4.99) 141 613043.94 | 347697.68 | +3.08(+10.10) ‘| 128A 613128.15 348014.32 112A 613021.88 | 347691.2 42.51 (+8.23) 128B 613124.4 348014.23 | +4.02 (413.18) 1128 613023.25 | 347687.39 _| +1.90 (+6.23) 128C 613126.62 348018.07 _ | +4.16 (+13.65) 112C 613018.97 | 347688.68 _| +1.84 (+6.03) 129A 613125.02 348038.26 | +2.67 (+8.75 113A 613017.19 | 347707.15 _| +3.94 (+12.94) 1298 613123.2 348034.23 | 42.50 (+8.21) 613017.5 34770285 |43.69(412.11) | 129C 613121.19 348037.76 | +1.96 (+6.43 113C [613013.82 | 347705.07 _| +3.34 (+10.96) 130A 613134.26 348071.09 _ | +2.33 (+7.64) 114A 613019.98 | 34773252 | +3.49 (+11.44) 130B 613130.51 348070.43 | +1.64 (+5.38 114B 613016.39 | 347732.6 42.68 (+8.80) 130C 613132.21 348074.4 | 41.68 (+5.51)_ 114C 613018.69 | 347736.36 _| +2.88 (+9.44) 131A 613152.18 348082.16 | +4.40 (+14.43) 115A 613021.23 | 34775453 _| +2.12 (+6.97) 131B [613148.19 34808194 | 43.75 (412.30) 115B 613017.73 | 347753.05 _| +1.41 (+4.64) 131C 613150.37 348085.9 _| +3.88 (+12.74) 115C 613019.02 | 347757.36 _| +1.33 (+4.37) 132A ali 3150.71 348098.13 _| +3.35 (+11.00 116A 613037.06 | 34777454 _| +3.91 (+12.83) 132B 613146.9 348097.78 | +2.66 (+8.74) 116B 613035.4 347770.45 _| +3.83 (+12.57) 132C 613148.97 348101.85 | +2.77 (+9.10) 116C 613033.31 | 347773.63 | 43.21 (+10.53)__| 133A 613150.34 348114.57 | +2.23 (47.33) 117A 613044.98 | 347801.14 _| +3.58 (+11.73) 1338 613146.7 348115.04 | 41.45 (+4.77) 133C 613149.15 348118.62 613115.86 347866.31 +1.18 (43.86) 613104.54 347833.03 +1.11 (+3.65) 613091.14 347800.6 +1.47 (+4.81) 613079.22 347764.36 +1.17 (+3.85) 613068.31 347733.16 +1.26 (+4.13) 613056.29 347698.03 +1.07 (+3.52) | 613026.24 347682.84 +1.13 (43.72) _ 613004.55 347715.89 +1.59 (+5.23) _ 613015.11 347748.17 +1.22 (+4.01) 613025.98 347781.52 | +1.05 (+3.43) ie 613041.47 347819.48 +1.48 (+4.84) 613051.09 347850.2 +1.11 (+3.65) 613064.22 347885.45 +1.34 (+4.39) 613077.79 347919.07 +1.48 (+4.86) 613089.89 347952.23 +1.48 (+4.85) 613099.85 347985.46 +1.26 (+4.13) 613113.36 348020.82 +1.51 (+4.97) 613124.3 348051.52 +1.78 (+5.85) 613136.88 [348087 34 +1.52 (+5.00) 613148.57 348123.44 +1.47 (+4.81 Table 2 Centroid Data and Orientations of Targeted Tribars (Units with Three Targets) fro October 1996 Ground Surve Centroid Coordinates Rotation Angle (deg) Elevation (z), m (ft axis Z axis 613108.579 347894.019 +3.84 (+12.60) 613104.024 347870.916 +3.05 (+10.01) 613106.971 347852.125 +1.24 (+4.07) 613084.605 347835.607 +4.27 (414.01) 613084.504 347815.411 +3.01 (+9.87) 613087.182 347797.238 +1.26 (+4.12) 613068.053 347781.411 +3.76 (412.35) _| 613065.224 347754.511 +2.51 (+8.25) 613065.068 347735.306 +1.26 (+4.13) 613042.758 347720.871 +4.20 (+13.78) 613044.329 347700.716 +2.67 (+8.75) 613021.721 347690.149 +1.55 (45.10) 613016.957 347705.436 +3.09 (+10.15) 613019.479 347733.302 +2.51 (+8.25) 613020.584 347754.555 | +1.14 (43.75) 613036.294 _| 347772.589 +3.12 (410.23) 613044.22 347801 .527 +2.60 (+8.52) 613046.31 347818.553 +1.73 (+5.69) 613063.377 347836.493 +3.77 (+12.38) 613066.95 347863.894 +2.50 (+8.21) 613065.606 347878.776 +1.21 (+3.97) 613085.457 347897.608 +3.91 (+12.81) 613087.157 347919.796 +2.44 (+8.01) 613090.008 347947.495 +1.05 (+3.44) 613109.591 347965.886 +3.67 (412.06) 613110.395 347987.746 +2.45 (48.04) _ 613109.576 348003.302 +1.18 (+3.87) 613127.374 348015.12 +3.75 (+12.30) 613124.158 348036.495 +1.84 (+6.03) 613133.414 348071 .545 +1.37 (+4.48) 613151.207 348082.985 | +3.47 (+11.37) 613149.889 | 348098.821 +2.40 (+7.88) 613149.806 348115.705 Table 3 Ground Survey Data Depicting Representative Armor Unit Target Positions as a Result of March 1997 Survey and Differences Relative to the October 1996 Ground Surve Absolute Value of Difference Between October 1996 and March 1997 Ground Survey March 1997 Ground Survey Data Target ID Easting (x) |613111.46 Northing (y) 1347895.41 EI (z), m (ft) +4.09 (+13.42 Easting, cm (ft) 1.83 (0.06) 613107.12 $3.13 (+10.28) 1.22 (0.04) Northing, cm (ft) 0.61 (0.02 El, cm (ft) 1.83 (0.06 1.83 (0.06 aS 613105.89 _|347869.82 347852.15 +2.18 (+7.16) 1.22 (0.04) 0.91 (0.03) 0.30 (0.01) 1.22 (0.04 613087.38 347813.91 +3.11 (+10.19) 1.83 (0.06) _ 0.30 (0.01) 613066.67 347751.72 +2.82 (+9.24) 1.22 (0.04) 0.91 (0.03 613064.15 347735.64 +2.21 (+7.26) 0.61 (0.02) _ 0.61 (0.02 613043.82 347718.01 613047.52 347700.58 0.61 (0.02) 0.000.002) +4.60 (+15.09) +2.98 (+9.79) 2.44 (0.08) 0.00 (0.00) 2.44 (0.08 0.91 (0.03 1.22 (0.04 0.91 (0.03 1.22 (0.04 613021.85 347691.17 +2.50 (+8.19) 0.91 (0.03) 0.91 (0.03) 1.22 (0.04) 613013.46 347705.00 613018.68 347736.37 +3.27 (+10.73) 10.97 (0.36) 2.13 (0.07) 7.01 (0.23) +2.87 (+9.41) | 0.30 (0.01) 0.30 (0.01) 0.91 (0.03)_ 613019.02 347757.30 613037.04 347774.51 +1.32 (+4.34) {0.00 (0.00) 1.83 (0.06) 0.91 (0.03 +3.90 (+12.79) 0.61 (0.02) 0.91 (0.03) 1.22 (0.04) 613042.88 347804.42 +2.87 (+9.40) 0.00 (0.00) 0.30 (0.01) 1.52 (0.05 613043.25 347819.60 +1.77 (+5.81) 0.61 (0.02) _ 0.30 (0.01) 1.52 (0.05) 613064.14 _|347836.16 +4.73 (+15.53) 0.00 (0.00) _ 1.83 (0.06) 2.44 (0.08) __|613062.21 347839.48 +4.03 (+13.22) 0.91 (0.03) _ 0.00 (0.00) 0.91 (0.03) 613065.71 347866.77 +2.80 (+9.20) 1.22 (0.04) 0.00 (0.00) 1.22 (0.04) 613085.97 347896.79 +4.85 (+15.92) [0.91 (0.03) 2.74 (0.09) 2.44 (0.08) 613082.36 347896.51 +4.05 (+13.28) 1.22 (0.04) 0.91 (0.03) ‘| 613088.01 347919.33 +3.38 (+11.10) [0.61 0.02) 0.30 (0.01) 0.64 (0.02) 0.91 (0.03 613088.59 347950.18 +1.34 (+4.38) 6.40 (0.21) 1.83 (0.06 613106.47 347964.68 +3.86 (+12.68) 2.13 (0.07) 5.18 (0.17) 613107.36 | 347986.75 +2.69 (+8.81) 0.61 (0.02) 1.22 (0.04) 0.30 (0.01 613128.45 348014.31 +4.64 (+15.23) 9.14 (0.30) 0.30 (0.01) ) ) 0.30 (0.01) ) ) 3.35 (0.11 613124.38 348014.20 +4.01 (+13.15) ( ( ( ( 4.57 (0.15) ( ( ( ( 0.61 (0.02) _ 0.91 (0.03) 0.91 (0.03) 613126.54 348018.06 +4.15 (+13.63) [0.6 2.44 (0.08) 0.30 (0.01) 0.61 (0.02) 613124.99 348038.26 +2.66 (+8.73) 0.91 (0.03) 0.00 (0.00) 0.61 (0.02) 613123.20 | 348034.22 +2.50 (+8.19) 0.00 (0.00) 0.30 (0.01) 0.61 (0.02) 613134.23 _|348071.06 0.91 (0.03) 0.91 (0.03) 0.30 (0.01 613130.59 348070.46 +1.64 (+5.37) 2.44 (0.08) _ 0.91 (0.03) 0.30 (0.01 613132.21 = 348074.41 +1.67 (+5.49) {0.00 (0.00) 0.30 (0.01) 0.61 (0.02) _ 613152.19 348082.14 ( ( ( ( +2.33 (+7.63) ( ( ( 0.30 (0.01) 0.61 (0.02 0.30 (0.01) 613148.21 348081.87 +4.40 (+14.42 +3.75 (412.29) 0.61 (0.02) 0.30 (0.01) 613150.34 348085.81 $3.88 (+12.72) 0.91 (0.03) ) 2.13 (0.07) ) _|2.74 (0.09 0.61 (0.02) 613150.71 348098.08 +3.35 (+10.98) 0.00 (0.00) 1.52 (0.05) 0.61 (0.02) 613146.92 348097.74 +2.66 (+8.72 ) 0.61 (0.02) 1.22 (0.04). 0.61 (0.02 613148.96 348101.78 +2.77 (+9.08) 0.30 (0.01) 2.13 (0.07) 0.61 (0.02 613146.78 348115.03 +1.46 (+4.78) 2.44 (0.08) 0.30 (0.01) 0.30 (0.01) _ 613149.16 348118.68 +1.75 (45.75 0.30 (0.01 1.83 (0.06 0.30 (0.01 Table 4 Ground Survey Data Depicting Representative Armor Unit Target Positions as a Result of June 1997 Survey and Differences Relative to the October 1996 Ground Surve Absolute Value of Differences Between June 1997 Ground Survey Data Target ID | Easting (x) 613107.75 October 1996 and June 1997 Ground Survey Northing (y) |347894.35 EI (z), m (ft) +4.79 (+15.73) Easting, cm (ft) 0.30 (0.01) Northing, cm (ft) 0.91 (0.03) El, cm (ft) 1.22 (0.04 613111.41 613110.01 347895.44 +4.10 (+13.45) 0.30 (0.01 0.30 (0.01) 0.91 (0.03 347891.18 +4.12 (+13.51) 0.61 (0.02) 1.22 (0.04 613103.24 347868.76 +3.79 (+12.48) ) 0.00 (0.00) 0.61 (0.02) 0.30 (0.01) 1.22 (0.04 613104.70 347873.00 +3.79 (+12.44) 1.52 (0.05 0.00 (0.00) 613107.05 347869.81 +3.14 (+10.29) 0.91 (0.03 0.61 (0.02) 1.52 (0.05) 613105.91 347852.16 +2.19 (+7.18) 1.83 (0.06 0.61 (0.02) 0.61 (0.02) 613109.52 347853.82 +1.60 (+5.25) 0.61 (0.02) 0.91 (0.03) 613108.63 347849.42 +1.49 (+4.90) 1.52 (0.05 0.30 (0.01) 0.91 (0.03) 613084.22 347833.30 +4.99 (+16.36) 0.30 (0.01 0.91 (0.03 0.30 (0.01) 613087.78 347835.08 +4.39 (+14.40) 613083.50 347813.75 +3.84 (+12.61) ) ) ) 0.91 (0.03) ) ) ) | 1.22 (0.04 0.30 (0.01) 0.91 (0.03) _ {0.30 (0.01 0.00 (0.00) 613085.69 347817.58 +3.67 (+12.04) ( 0.91 (0.03 ( ( 0.30 (0.01) ) ) ) ) 1.22 (0.04 0.00 (0.00) 613087.34 347813.93 +3.13 (+10.26) 0.61 (0.02) 0.91 (0.03) 0.30 (0.01) 613086.27 347797.30 +2.21 (+7.26) 0.61 (0.02) 0.00 (0.00) |0.30 (0.01) 613088.79 347794.56 +1.51 (+4.94) 0.00 (0.00) 0.30 (0.01) 0.00 (0.00) _ 613066.91 347781 .34 +4.69 (+15.38) 1.52 (0.05) 1.83 (0.06) 613070.38 347783.21 +4.15 (413.63) 1.52 (0.05) 0.00 (0.00) 613069.78 347778.80 +4.06 (+13.33) 1.83 (0.06) 1.22 (0.04) 613064.20 347754.80 +3.47 (+11.37) 0.30 (0.01) 0.30 (0.01) 613067.99 347756.01 +2.83 (+9.30) 0.61 (0.02) 0.30 (0.01) _ 613066.59 347751.74 +2.82 (+9.26) 1.22 (0.04) 0.30 (0.01) 0.30 (0.01) 613064.15 347735.68 +2.22 (+7.29) 0.61 (0.02) 0.61 (0.02) 0.30 (0.01) 613067.89 347736.67 +1.55 (+5.08) 0.61 (0.02). 0.91 (0.03) 0.30 (0.01) 613066.51 347732.45 +1.55 (+5.10) 1.22 (0.04) 0.30 (0.01) 0.61 (0.02) 613041 .56 347721.48 +5.11 (+16.75) 1.22 (0.04) 2.13 (0.07) 1.22 (0.04) 613045.60 347722.13 |+4.55 (+14.92) 0.61 (0.02) 0.91 (0.03) 0.91 (0.03 613043.83 347718.02 +4.61 (+15.11) 0.91 (0.03) 0.30 (0.01) 0.30 (0.01 613043.68 347701.78 +3.58 (+11.75) 0.30 (0.01) 0.00 (0.00) 613047.50 347700.59 +2.99 (+9.81) 1.83 (0.06) | 0.30 (0.01) ) ) 0.30 (0.01) {¢ 0.61 (0.02) 613043.98 347697.66 +3.07 (+10.08) 1.22 (0.04) _ 0.61 (0.02) 4c 0.61 (0.02) 613021.85 347691.11 +2.50 (+8.20) 0.91 (0.03) 2.74 (0.09) 613018.92 347688.58 +1.82 (+5.98) 1.52 (0.05) 3.05 (0.10) 1.52 (0.05) 613016.95 347706.80 +3.91 (+12.82) 7.32 (0.24) 10.67 (0.35) 3.66 (0.12) 613017.02 347702.53 +3.61 (+11.84) 14.63 (0.48) 9.75 (0.32) 8.23 (0.27) 613013.47 us 347705.00 +3.28 (+10.75) _| 10.67 (0.35) 2.13 (0.07) _ 6.40 (0.21) 613019.94 347732.51 +3.41 (411.20) 1.22 (0.04) 0.30 (0.01) _ ( ( ( ( |0.91 (0.03) ( ( ( ( ( 7.32 (0.24) 613016.33 347732.58 +2.68 (+8.79) 1.83 (0.06) 0.61 (0.02) _ 0.30 (0.01) 613021 .24 347754.62 +2.12 (+6.95) 0.30 (0.01) 2.74 (0.09) _ 0.61 (0.02) 613017.73 347753.11 +1.41 (+4.62) 0.00 (0.00) 1.83 (0.06) 613036.98 613019.03 347757.46 +1.33 (+4.35) 0.30 (0.01) 3.05 (0.10) _ 347774.54 +3.90 (+12.81) 2.44 (0.08) 0.00 (0.00) 613035.32 347770.43 __ | +3.82 (+12.54) 2.44 (0.08) 0.61 (0.02). 0.91 (0.03) __ 613033.22 347773.82 +3.20 (+10.51) 2.74 (0.09) 0.30 (0.01) 0.61 (0.02) _ 613044.96 347801.14 +3.57 (411.71) 0.61 (0.02) 0.00 (0.00) _ 0.61 (0.02) _ 613041 .32 347800.36 +2.84 (+9.31) 0.00 (0.00 1.22 (0.04) {0.61 (0.02) _ 613042.86 347804.39 +2.88 (+9.44) 0.61 (0.02 0.61 (0.02) {0.30 (0.01) 613046.89 347820.81 +2.45 (+8.04)_ 0.91 (0.03)_ 0.61 (0.02) 613047.42 347316.13 +2.50 (+8.21) 6.71 (0.22 12.80 (0.42) 0.30 (0.01) _ 613043.25 347819.59 +1.78 (+5.84) ) ) 0.00 (0.00) ) ) 0.61 (0.02 able 4 (Concluded Absolute Value of Differences Between October 1996 and June 1997 Ground Surve dune 1997 Ground Survey Data 613064.13 347836.05 +4.75 (415.57) _ 3.30 (0.01 ) 1.52 (0.05) 1.22 (0.04 613060.38 347835.44 +4.02 (+13.19) 0.61 (0.02) 0.30 (0.01 613062.22 347839.47 __|+4.04 (413.25) 0.61 (0.02) 0.30 (0.01 613067.76 347863.42 +3.46 (411.35) 0.30 (0.01) 613064.00 +* 347862.60 +2.77 (+9.10) 0.30 (0.01) 613065.73 347866.77 +2.81 (+9.23) 0.61 (0.02) 2.13 (0.07 0.30 (0.01 0.00 (0.00 0.00 (0.00) 0.91 (0.03) 0.30 (0.01 0.00 (0.00) 0.30 (0.01 613066.46 347878.34 +2.18 (+7.16) 0.30 (0.01) 3.05 (0.10) 613062.77 347877.42 +1.49 (+4.89) 0.61 (0.02) 1.52 (0.05 613064.33 347881.58 +1.50 (44.91) 3.66 (0.12) 1.52 (0.05 613086.02 347896.84 | +4.87 (+15.99 0.61 (0.02) 1.22 (0.04 613082.46 347896.50 +4.05 (+13.30 2.44 (0.08 1.52( 0.05) 613084.43 347900.50 0.61 (0.02 2.13 (0.07) 0.30 (0.01 0.00 (0.00 0.30 (0.01 0.30 (0.01 0.30 (0.01 0.30 (0.01 613087.96 347919.34 ) ) [44.27 (414.01) ) +3.40 (411.14 1.83 (0.06 0.30 (0.01) 0.30 (0.01 613084.23 ‘| 347918.57 +2.73 (48.97) 1.22 (0.04) 0.00 (0.00 613086.00 347922.71 +2.76 (+9.05 1.22 (0.04 1.22 (0.04) 613091.02 347947.09 0.30 (0.01 1.83 (0.06) 0.30 (0.01 0.30 (0.01) 613087.18 | 347946.20 +1.38 (44.52 ) ) ) 0.61 (0.02) ) ) ) 0.91 (0.03 1.83 (0.06) 0.00 (0.00 613088.73 347950.39 ) +2.00 (+6.55) ) +1.35 (+4.44) 0.30 (0.01) 0.00 (0.00) _ 0.00 (0.00 613110.12 347965.35 +4.65 (+15.26 0.00 (0.00) 2.74 (0.09) 613106.52 347964.80 0.61 (0.02) 1.52 (0.05) 0.30 (0.01 0.00 (0.00) _ 613108.49 347968.86 +3.96 (+12.99 0.30 (0.01) 1.52 (0.05) 0.30 (0.01) _ 613111.16 347986.98 ) +3.87 (+12.69) ) ) +3.40 (411.15 1.22 (0.04) 0.00 (0.00) 0.30 (0.01) _ 613107.48 347986.74 +2.69 (+8.82) 3.05 (0.10) 1.52 (0.05) 0.00 (0.00) _ 613109.56 347990.68 +2.84 (+9.32 0.91 (0.03) 1.22 (0.04) 0.30 (0.01) 613110.28 348002.63 +2.14 (+7.02 1.22 (0.04) _ 0.91 (0.03) 0.30 (0.01) 613106.62 348002.24 0.00 (0.00) 3.96 (0.13) 11.58 (0.38) 613108.63 348006.34 ) ) +1.52 (44.99) +1.51 (+4.97) 0.91 (0.03) _ 0.91 (0.03) 0.61 (0.02) 613128.18 348014.28 +4.67 (+15.33) 0.91 (0.03) 1.22 (0.04) 0.30 (0.01 613124.43 348014.20 +4.01 (+13.16) 0.91 (0.03) 0.91 (0.03) 0.61 (0.02 613126.66 348018.04 +4.16 (+13.64) 1.22 (0.04) 0.91 (0.03) 0.30 (0.01 613125.04 348038.21 +2.66 (+8.73 0.61 (0.02) _ 1.52 (0.05) 613123.18 348034.16 +2.50 (+8.20 0.61 (0.02) 2.13 (0.07 0.30 (0.01 613121.16 348037.72 +1.96 (+6.42 0.91 (0.03) 1.22 (0.04 0.30 (0.01 613134.25 |348071.04 0.30 (0.01) 1.52 (0.05 ) ) ) 0.61 (0.02) ) ) ) 0.30 (0.01 613130.48 348070.29 +1.63 (+5.36 0.91 (0.03) 4.27 (0.14 0.61 (0.02 613132.19 348074.35 ) ) ) +2.33 (+7.65) ) ) +1.67 (+5.49 0.61 (0.02) 0.61 (0.02 613148.22 348081.88 +3.75 (+12.30) 0.91 (0.03) 1.83 (0.06 0.00 (0.00 613150.38 348085.82 +3.88 (+12.73) 0.30 (0.01) 0.30 (0.01) 613150.75 348098.10 +3.35 (+10.98) 1.22 (0.04) ( ( 2.44 (0.08 0.91 (0.03 0.61 (0.02) 613146.92 348097.71 +2.66 (+8.73) 0.61 (0.02) ) ) ) ) 1.52 (0.05) ) ) ) ) 2.13 (0.07 0.30 (0.01) 613148.97 348101.75 +2.77 (+9.09) 0.00 (0.00) 3.05 (0.10) 0.30 (0.01) 613150.28 348114.55 +2.23 (47.30) 1.83 (0.06) 0.61 (0.02) 0.91 (0.03 613146.73 348115.02 +1.44 (+4.73) 0.91 (0.03) 0.61 (0.02) __|1.22 (0.04 613149.27 348118.64 +1.70 (+5.57 3.66 (0.12 0.61 (0.02 5.79 (0.19 able 5 Aerial Survey Data Depicting Armor Unit Target Positions as Result of October 1996 Survey and Differences Relative to the October 1996 Ground Surve October 1996 Aerial Survey Data Absolute Value of Differences Between October 1996 Aerial and Ground Survey 613107.64 347894.09 613111.30 347895 .24 + 4.81 (+15.77) 3.05 (0.10) Northing, cm (ft 8.84 (0.29) 0.00 (0.00) $4.11 (+13.48) 613109.88 347891 .04 613103.19 347868.66 3.05 (0.10 5.79 (0.19) 0.00 (0.00) +4.12 (413.52) 3.96 (0.13 3.96 (0.12) 0.91 (0.03) $3.77 (+12.38) 2.13 (0.07 3.35 (0.11) 2.74 (0.09) 613104.72 347873.04 +3.78 (+12.39) 613106.99 347870.00 0.91 (0.03 1.22 (0.04) 3.05 (0.10 +3.08 (+10.10) 6.40 (0.21) 613105.65 347851 .89 613109.52 -|347854.05 +2.23 (+7.32) 6.10 (0.20 7.62 (0.25) ) 7.32 (0.24) 3.66 (0.12) +1.57 (+5.15) | 0.91 (0.03 6.40 (0.21) 613108.59 347849.69 ) ) ) ) 2.74 (0.09) ) ) ) +1.45 (+4.76) | 2.74 (0.09 0.09 (0.28) 5.18 (0.17 613084.14 _|347832.91 +4.99 (+16.37) _ | 2.74 (0.09) 10.97 (0.36) 0.61 (0.02 613084.89, 347837.62 +5.00 (+16.40 0.30 (0.01) 0.30 (0.01) 613087.74 347834.99 2.13 (0.07) 3.96 (0.13) 3.05 (0.10 613083.39 347813.47 +3.84 (+12.61 4.27 (0.14) 8.23 (0.27) ( ( ( ( ( ( 3.96 (0.130) ( ( ( ( 0.00 (0.00 613085.57 347817.36 ) +4.36 (+14.31) ) ) +3.69 (+12.10 3.96 (0.13) _ 7.92 (0.26) ) ) 4.88 (0.16) ) ) ) 1.83 (0.06 613087.36 347814.16 +3.03 (+9.94) 1.22 (0.04) | 7.92 (0.26) 10.06 (0.33) 613086.14 347797.09 +2.22 (+7.29) 4.57 (0.15) 6.40 (0.21) 0.61 (0.02) _ 613089.79 347798.80 +1.55 (+5.09) _| 3.66 (0.12) 1.22 (0.04) 2.74 (0.09) 613088.59 347794.47 +1.51 (+4.95) [6.10 (0.20 3.05 (0.10 0.30 (0.01) 613066.91 347781 .27 +4.65 (+15.27) 3.96 (0.13) 3.35 (0.11) _ 613070.33 347782.97 +4.15 (+13.63) 3.05 (0.10 7.32 (0.24) 0.00 (0.00) 613069.74 347778.60 +4.05 (+13.29) ) [1.52 (0.05) ) ) 3.05 (0.10 7.32 (0.24 1.22 (0.04) 613064.08 347754.61 +3.48 (+11.48) 3.96 (0.13). 5.49 (0.18 1.83 (0.06) 613067.93 347756.08 +2.79 (+9.15) 2.44 (0.08) _ 2.44 (0.08 4.88 (0.16) 613066.51 347751.77 +2.80 (+9.20) 3.66 (0.12) 0.61 (0.02 2.13 (0.07) 613064.07 347735.72 +2.21 (+7.26) 1.83 (0.06) 1.83 (0.06 1.22 (0.04) 613067.72 347736.52 _|+1.59 (+5.21) 4.57 (0.15) 3.66 (0.12 3.66 (0.12) 613066.31 347732.43 +1.59 (+5.22) 4.88 (0.16) 0.91 (0.03) 3.05 (0.10) 613041.49 347721 .37 +5.12 (+16.79) 3.35 (0.11) 5.49 (0.18) 0.00 (0.00) 613045.50 347721.98 +4.55 (+14.94) 2.44 (0.08) 3.66 (0.12) 1.52 (0.05) 613043.80 613043.58 347718.01 +4.58 (+15.04) 0.00 (0.00) _ 0.00 (0.00) 2.44 (0.08) 347701 .62 +3.64 (11.94) 2.74 (0.09) 4.88 (0.16) 5.49 (0.18) 613047.43 347700.80. +2.96 (+9.71) 0.30 (0.01) 6.71 (0.22) 3.66 (0.12) 613043.98 347697.86 +3.06 (10.03) 1.22 (0.04) 5.49 (0.18) 2.13 (0.07) 613022.06 347690.94 +2.49 (+8.17) 5.49 (0.18) | 7.92 (0.26) 1.83 (0.06) 613019.10 613023.31 347687.42 +1.92 (+6.29) | 1.83 (0.06) 0.91 (0.03 1.83 (0.06) | 347688.79 +1.84 (46.03) _ 3.96 (0.13) 3.35 (0.11 0.00 (0.00) _ 613017.27 | 347706.98 +3.93 (+12.90) 2.44 (0.08) [5.18 (0.17 1.22 (0.04) _ 613017.63 347702.64 3.96 (0.13) 6.40 (0.21 2.13 (0.07) 613013.89 347704.91 +3.33 (+10.93)_ +3.67 (+12.04) 2.13 (0.07) 0.91 (0.03)_ 613020.06 347732.45 +3.47 (411.38) _ 2.44 (0.08) _ [2.13 0.07 1.83 (0.06) 613016.54 347732.51 +2.64 (+8.67) _ 4.57 (0.15) 2.74 (0.09 3.96 (0.13) 613018.86 613021.35 347736.36 +2.85 (+9.34) _ 5.18 (0.17) ) ) ) ) 4.88 (0.16) ) ) ) 0.00 (0.00 3.05 (0.10) 347754.57 +2.09 (+6.86) 3.66 (0.12) ‘| 1.22 (0.04) 3.35 (0.11) 613017.85 347753.07 | 41.38 (+4.53) 3.66 (0.12) 0.61 (0.02) 3.35 (0.11) 613019.09, 347757.38 +1.31 (+4.29) 0.61 (0.02) 2.44 (0.08) 613037.28 347774.60 +3.88 (+12.73) [6.71 (0.22) 1.83 (0.06) 3.05 (0.10) 613035.46 347770.46 +3.85 (+12.62) ( | 2.13 (0.07) ( ( _| 4.83 (0.06) 0.30 (0.01) 1.52 (0.05) 613033.60 347773.96 +3.15 (+10.32 8.84 (0.29 3.96 (0.13 6.40 (0.21 able 5 (Concluded October 1996 Aerial Survey Data Easting (x) 613045.14 Northing (y) |347801.32 EI (2), m (ft) Easting, cm (ft) +3.55 (+11.65) | 4.88 (0.16) Northing, cm (ft) 5.49 (0.18 613041.57 347800.49 +2.81 (49.22 7.62 (0.25) 5.18 (0.17 613043.14 347804.59 +2.83 (+9.29) 7.29 (0.26) 613047.04 347821.03 +2.43 (+7.97) 4.57 (0.15) 5.49 (0.18 5.79 (0.19) 613045.65 347816.71 +2.50 (+8.19) 3.96 (0.13 4.88 (0.16) Absolute Value of Differences Between October 1996 Aerial Ground Surveys 0.91 (0.03) 613043.41 347819.81 +1.76 (+5.78) _ | 4.27 (0.14) 6.10 (0.20) 613064.06 347836.05 +4.80 (+5.74) 2.44 (0.08) 1.52 (0.05 613060.36 347835.54 +4.06 (+13.33) 0.00 (0.00) 2.74 (0.09 | 613062.46 347839.71 +4.02 (+13.20) 7.01 (0.23) 613067.86 347863.65 +3.46 (+11.36) 2.74 (0.09) 4.88 (0.16 _|613064.20 613065.90 347866.97 347862.88 +2.76 (+9.04) ( ( ( 6.71 (0.22) ( ( 5.79 (0.19) +2.80 (+9.20 4.57 (0.15) 613066.55 347878.65 2.44 (0.08) 613062.96 347877.65 ) +2.16 (+7.09) +1.44 (+4.73) 5.18 (0.17) 7.62 (0.25 2.44 (0.08 2.13 (0.07) 1.22 (0.04) 6.40 (0.21 1.83 (0.06) 5.49 (0.18 4.88 (0.16 613064.23 347881.77 +1.52 (+4.99) 0.61 (0.02) ) ) __|6.10 (0.20) ) ) ) 4.27 (0.14 2.13 (0.07 613086.27 347897.19 +4.86 (+15.93) 8.23 (0.27) 9.45 (0.31) 2.13 (0.07 613082.74 347896.93 +4.00 (+13.13) 10.97 (0.36) {11.58 (0.38) 5.49 (0.18 613084.54 347900.77 +4.28 (+14.04) 3.96 (0.13) 6.10 (0.20) 0.61 (0.02 613088.28 347919.75 +3.36 (+11.01) 7.92 (0.26) 12.19 (0.40) 3.66 (0.12 613084.61 347919.01 +2.65 (+8.69) | 10.97 (0.36) 12.19 (0.40) 8.53 (0.28 613086.05 347922.94 +2.77 (+9.10) | 0.30 (0.01 5.79 (0.19) 1.22 (0.04 613090.99 347947.24 +1.98 (+6.51) 0.61 (0.02 2.74 (0.09) 1.52 (0.05 613087.01 347946.36 +1.36 (+4.45) _ 6.10 (0.20 3.05 (0.10) 2.13 (0.07 613088.52 347950.50 +1.39 (+4.57) 6.71 (0.22 3.35 (0.11) 3.96 (0.13 613110.04 347965.32 +4.66 (+15.28) 2.44 (0.08 3.66 (0.12) 3.0 (0.01 613106.54 347964.82 +3.86 (+12.65) 0.00 (0.00 0.91 (0.03) 1.22 (0.04 613108.56 347968.93 +3.95 (+12.95) 0.61 (0.02) 0.91 (0.03 613111.05 347986.99 +3.42 (+11.21) [0.30 (0.01 2.13 (0.07 613107.35 347986.80 613109.47 347990.69 +2.86 (+9.38) +2.69 (+8.81) 0.91 0.03 0.30 (0.01 0.30 (0.01 1.83 (0.06 0.91 (0.03 1.52 (0.05 613110.35 348002.79 +2.12 (46.94) _ 3.35 (0.11 ) ) ) ) [3.96 0.13 2.74 (0.09) 613106.69 348002.48 __ | 41.39 (+4.57) _ 2.13 (0.07 3.35 (0.11) 1.22 (0.04) 613108.62 348006.52 +1.51 (+4.96) _ ( ( ( ( ( 1.83 (0.06 ( ( ( ( ( ( 0.61 (0.02 4.57 (0.15) 0.91 (0.03) 613128.15 348014.22 +4.86 (+15.35) ) ) ) ) ) ) ) 2.13 (0.07) ) ) ) ) ) ) 0.00 (0.00 3.05 (0.10) 0.30(0.01) 613124.43 348014.33 ‘| 43.99 (413.10) 0.91 (0.03) 3.05 (0.10) 2.44 (0.08) 613126.64 348018.16 0.61 (0.02) 2.74 (0.09) 1.22 (0.04 613124.93 348038.32 ( ( +4.15 (413.61) +2.65 (48.71) 2.74 (0.09) 1.83 (0.06) 1.22 (0.04 613123.14 348034.26 +2.51 (+8.22) 1.83 (0.06 613121.09 | 348037.72 +1.98 (+6.50) 3.05 (0.10 1.22 (0.04) 0.91 (0.03) 0.30 (0.01 2.13 (0.07) 613134.33 _|348070.95 +2.32 (+7.62) | 2.13 (0.07 4.27 (0.14) 0.61 (0.02) 613130.68 | 348070.40 +1.59 (+5.23) 5.18 (0.17 0.91 (0.03) 4.57 (0.15) 613132.31 348074.41 +1.65 (+5.42) _ 0.30 (0.01) 2.74 (0.09) 613152.24 348082.29 +4.40 (+14.42) 1.83 (0.06 3.96 (0.13) 0.30 (0.01) 613148.20 613150.38 348085.95 613150.76 348098.23 348081.75 +3.74 (+12.27) 0.30 (0.01 5.79 (0.19) 0.91 (0.03 +3.87 (+12.71) ) ) ) ) 3.05 (0.10) ) ) ) 0.30 (0.01 1.52 (0.05) 0.91 (0.03) +3.35 (+10.99) 1.52 (0.05) 3.05 (0.10) 0.30 (0.01) 613146.95 348097.75 +2.69 (+8.83) 1.52 (0.05) [0.91 (0.03) 2.74 (0.09) 613149.05 348101.85 | +2.78 (+9.12) 2.44 (0.08) 0.00 (0.00) 0.61 (0.02 _|613150.25 348114.59 +2.21 (+7.25)_ 2.74 (0.09) 0.61 (0.02) 2.44 (0.08), 613146.59 348114.95 +1.48 (+4.85) 3.35 (0.11) 2.74 (0.09) 2.44 (0.08) 613149.26 348118.48 +1.74 (+5.71 3.35 (0.11 4.27 (0.14 1.52 (0.05 REPORT DOCUMENTATION PAGE BENG Gooones 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, VA22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188), Washington, DC20503. 1.AGENCY USE ONLY (Leave blank) 2.REPORT DATE 3.REPORT TYPE AND DATES COVERED November 1997 Final report 4.TITLE AND SUBTITLE 5.FUNDING NUMBERS Periodic Inspection of Ofu Harbor Breakwater, American Samoa; Report 1, Base Conditions 6.AUTHOR(S) Robert R. Bottin, Jr., Stanley J. Boc 7.PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8.PERFORMING ORGANIZATION U.S. Army Engineer Waterways Experiment Station REPORT NUMBER 3909 Halls Ferry Road, Vicksburg, MS 39180-6199 Technical Report CHL-97-32 U.S. Army Engineer Division, Pacific Ocean Building 230, Fort Shafter, HI 96858-5440 | 9.SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10.SPONSORING/MONITORING AGENCY REPORT NUMBER U.S. Army 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) Selected navigation structures are periodically monitored under the periodic Inspections work unit of the Monitoring Completed Navigation Projects research program. Monitoring is done to gain an understanding of the long-term structural response of unique structures to their environment. Periodic data sets are used to improve knowledge in the design, construction, and maintenance of both existing and proposed projects. This report is the first in a series that will track the long-term structural response of the Ofu Harbor breakwater, American Samoa, to its environment. Data from limited ground-based surveys, aerial photography, and photogrammetric analysis were obtained to establish base level conditions for the Ofu Harbor breakwater. Although planned low-altitude photography was not obtained due to logistical problems, oblique images taken from a fixed-wing aircraft were analyzed using convergent photogrammetric techniques. A detailed walking survey of the structure resulted in a well-documented data set that can be compared to subsequent surveys. The Ofu Harbor breakwater site will be revisited to gather data to assess the long-term response of the structure to its environment. These data will facilitate engineering decisions concerning whether closer surveillance and/or repair of the (Continued) 14.SUBJECT TERMS 15.NUMBER OF PAGES Aerial photography Periodical Inspections 46 Breakwaters Photogrammetry 16.PRICE CODE Coastal navigation projects Remote sensing Ofu Harbor breakwater Tribars 17.SECURITY CLASSIFICATION |18.SECURITY CLASSIFICATION |19.SECURITY CLASSIFICATION | 20.LIMITATION OF ABSTRACT OF REPORT OF THIS PAGE OF ABSTRACT UNCLASSIFIED UNCLASSIFIED Sill NSN 7540-01-280-5500 Standard Form 298 (Rev. 2-89) Prescribed by ANSI Std, 239-18 298-102 13. (Concluded). structure might be requested to reduce its chances of failing catastrophically. The periodic inspection methodology developed and validated for the Ofu Harbor breakwater also may be used to gain insight into other Corps structures. Destroy this report when no longer needed. Do not return it to the originator. DEPARTMENT OF THE ARMY WATERWAYS EXPERIMENT STATION, CORPS OF ENGINEERS 3909 HALLS FERRY ROAD VICKSBURG, MISSISSIPPI 39180-6199 Official Business 266/L25/ 1 DATA/DOCUMENT LIBRARY, WHOI MCLEAN LAB, MS #8 360 WOOD HOLE ROAD WOODS HOLE MA 02543-1539 SPECIAL FOURTH CLASS BOOKS/FILM U.S. POSTAGE ei RBS 14 Di PE 1) 1 JAN2 1°98 H METER 5396092 | & x x wt * bs * *