FINAL-REPORT-TO12.pdf

Department Of The Army New York District Corps of Engineers Jacob K. Javits Federal Building 26 Federal Plaza New York, NY 10278-0090

Contract #DACW51-02-D-0005 (IDC #180) Delivery Order #0012

Geophysical & Subsurface Investigation S-AN-1 Contract Area

November, 2005

EARTHWORKS LLC

27 GLEN ROAD, NORTH ENTRANCE

SANDY HOOK, CONNECTICUT 06482

P.O. BOX 178, NEWTOWN, CT 06470

(203) 270-8100, FAX (203) 364-0480

WWW.EARTHWORKS2020.COM

All interpretations are opinions based on inferences from sonar or other measurements.

We cannot, and do not guarantee the accuracy or correctness of any interpretation. We shall not, except in the case of gross or willful negligence on our part, be liable or responsible for any loss, costs, damages or expenses incurred or sustained by anyone resulting from any interpretations made by any of our officers, agents or employees.

Executive Summary

Earthworks has mapped two water pipes in Contract Area S-AN-1 in the Anchorage Channel just north of the Verrazano Narrows Bridge. The estimated error in the locations is +-25ft. Tables 1 and 2 list estimated locations for each pipe, respectively.

Table ES-1. Observed locations of the northern water pipe in New Jersey State Plane.

Easting Northing 614,633.5 656,872.9 615,038.6 656,724.5 615,431.7 656,605.8 615,796.0 656,489.6 616,050.6 656,407.1 616,883.9 656,152.4

Table ES-2. Observed locations of the southern water pipe in New Jersey State Plane.

Easting Northing 615,602.1 653,107.7 616,282.3 653,100.7 616,644.0 653,126.9 616,994.3 653,133.5 617,354.3 653,135.2 617,664.0 653,136.6

The observed locations are based on (a) magnetometer measurement of magnetic field density and (b) independent sub-bottom measurement of seismic reflectivity. Detailed measurements were made in the neighborhood around the pipes. The two sets of measurements agree very well;

that is, within +-15ft.

Each of the observed pipe trajectories is 25 to 100ft north of the USACE planimetrics representing the pipe crossings in the channel.

Earthworks observed two other pipe trenches south the water pipes and north of the Verrazano Narrows Bridge. These pipes exhibit a distinct trajectory across the Anchorage Channel in S-AN-

1. The USACE did not charge Earthworks with more detailed measurements of these pipes.

Table of Contents

Disclaimer ..…………..……................................................………… Executive summary ..………................................................………… Table of contents …..……….................................................………… List of figures ….…..……….................................................………… List of tables …..…..……….................................................………… List of plates …..….....................................................……..............................................…………4

1. Introduction .….....................................................……..............................................…………5

2. Scope-of-work …….............................................…….......................................................……7

3. Methodology ............................………………….................................................................…8

4. Results …..............................………………...............................................................………9

5. Conclusions ……………………………..…............................................................………21 Appendix I. Comments on draft from USACE …………................................................………22 Appendix II. 11”x17” version of plates …………............................................................………23 Extended appendix. Independently supported measurements

List of Figures

1. Location map of contract area S-AN-1 …………..….……….........………………….……..6

2. Summary of all results and location of pipes ……..….……….........………………….……..10

3. Location of pipes from seismic results …………..….……….........………………….……..11

4. Location of pipes from seismic long lines ……..….……….........………………….……..12

5. Seismic section along long line ……..………..….……….........………………….……..13

6. Seismic section across northern trench …………..….……….........………………….……..14

7. Seismic section across southern trench …………..….……….........………………….……..15

8. Wiggle plot across southern trench ……..………..….……….........………………….……..16

9. Location of northern pipe based on all measurements ………………………………..……..17

10. Magnetic field density of northern pipe …..………..….................………………….……

11. Sub-bottom interpretation for disruption of strata in northern pipe area ……..……...……..18

12. Sub-bottom reflectors from northern pipe ………….........…………………….…….……..18

13. Location of southern water pipe from all methods ….........……………………..…….……..19

14. Magnetic field density of southern pipe ..…………………………………….…………

15. Sub-bottom interpretation for disruption of strata in southern pipe area ………….…..……..20

16. Sub-bottom reflectors for southern pipe area ………………………………...….…..……...20

List of Tables

ES-1. Coordinates of northern water pipe …………..……………………………….…...… ES-2. Coordinates of southern water pipe ..............…………………………………….…...…..3

1. Summary of magnetometer survey ……........…………………………………….…...…

2. Summary of seismic reflection survey ........…………………………………….…...…

3. Summary of geophysical measurements ........…………………………………….…...…

4. Coordinates of northern water pipe …………...………………………………….…...…

5. Coordinates of southern water pipe ..............…………………………………….…...…..9

Plates

1. Location map for contract areas S-AN-1

2. Interpretation of geophysical measurements for location of water pipes

1. Introduction

The New York District of the United States Army Corps of Engineers (USACE) assigned Earthworks under IDC#180, Contract # DACW51-02-D-0005, Task Order #0012, to produce a location of map of two water pipes in the Anchorage Channel. Figure 1 is a location map for the area-of-investigation (see Plate 1). The Corps is engaged in deepening the New York and New Jersey (NYNJ) harbor to 52ft. Plans and specifications for the dredging in S-AN-1 will depend on the results of this investigation.

The Corps authorized Earthworks to acquire magnetic field density measurements throughout the contract area. Given the neighborhood of the water pipes had been established, Earthworks focused more dense measurements in the local area. The more dense measurements included sub-bottom, chirp-seismic reflection to corroborate the magnetic field results. The magnetometer survey was acquired on June 20 and 21, 2005. The sub-bottom profiling data was acquired on May 10 and August 30, 2005. The surveying was coordinated with the USGC (United States Coast Guard) vessel traffic service (VTS), NY Activities, Fort Hamilton, Staten Island.

The scope-of-work indicated that Earthworks should identify other pipe crossings that might affect the dredging program for the Anchorage Channel deepening. Two additional pipe trenches were identified south of the water pipes and north of the Verrazano Narrows Bridge, This report including two CD-ROMs of the results in digital form completes the requirements with (a) maps of the measured pipe location, (b) the magnetic field density results, and (c) the sub-bottom results. The report includes a brief description of the methodology, results, and conclusions.

Figure 1. Location map for contract area S-AN-1including the area-of investigation and boring locations.

2. Scope-of-work

The Corps of Engineers assigned Earthworks LLC to conduct subsurface and geophysical exploration in the Anchorage Channel. The program consisted of magnetometer survey to define the location of two shallow water pipes in channel. Sub-bottom-profiling supplemented the magnetometer survey to corroborate the results independently.

TASK 1: Historical data, geophysical measurements, & interpretation – Magnetometer.

Earthworks has reviewed, evaluated, re-processed, and mapped existing geophysical, historical, and photographic data including personal communications for the design, engineering history, as-built information, shut-in and removal of any relevant pipeline crossings. The purpose was to determine the present configuration and state of the pipelines in the S-AN-1 contract area.

Earthworks obtained and reviewed historical and current photographs and NOAA charts.

Earthworks processed existing data with the purpose of identifying and charactering pipelines. A base-map was created on a recent aerial photograph. Earthworks performed walkouts for each of the pipelines from shore tie-in to the first surface intersection.

Earthworks focused the magnetometer survey with the primary objective being to better define the location of the two water lines. Earthworks conducted gradiometer/magnetometer survey of the area including cross-line tie-ins with a line of spacing roughly 100ft. The ten (10) lines across the channel were 9,000ft; the hundred and twenty (120) cross lines were 300ft. The secondary objective of the magnetometer investigation was to scan the entire contract area to confirm the location of other pipelines and to detect any unknown or undocumented structures. The secondary survey consisted of five (5) lines along the length of the channel (approximately 13,000ft.). The total length of the lines was 107,400 linear feet.

Table 1. Summary of magnetometer survey.

Measurement type Length of Survey (ft) Magnetic field density by magnetometer/gradiometer 107,400

TASK 2: Geophysical measurements & interpretation– Seismic reflection, map, and report. The single channel seismic reflection lines were used to benchmark the magnetometer results and improve the horizontal accuracy. The seismic reflection should be confined to image at least three

(3) areas on each pipe indicated by historical review and magnetometer surveys. The total length of the single channel seismic reflection lines were 3,000ft. in linear length. The geophysical data was processed. Interpretation of the data identified and characterized targets that include pipelines, pipe, pipeline trenches, obstacles, and debris. The presence of black silt was noted.

Preliminary reports of the data and interpretation indicated the objects of concern.

Table 2. Summary of seismic reflection survey.

Measurement type Length of survey (ft) Seismic reflection 3,000

Earthworks prepared a summary report that included the methodology, results and conclusions.

The methodology included the equipment used to gather and present the data. The geophysical data was presented at a horizontal scale that was adequate to illustrate the location of pipelines and was geo-referenced. The data was provided in an electronic format that can be used by other contractors at various scales and referenced to other drawings. Any anomalies or possible obstructions along the channel floor or side slopes were documented.

3. Methodology

Magnetometer survey. Earthworks used a Marine Magnetics Sea Spy magnetometer. The Sea Spy is based on the Overhauser method. The Sea Spy is sensitive to 0.1nT (0.1 nanoTelsa = 1 gamma = 0.001 Gauss). The Sea Spy sensor is insensitive to orientation with respect to the magnetic field, i.e., the Sea Spy sensor exhibits minimal directionality.

The Sea Spy was towed over 100ft behind the survey boat at a depth of depending on the speed of the boat. The magnetometer was weighted to achieve this depth. The channel depth is roughly 15 meters. The sensor was towed at roughly 6 meters.

The location was measured with the differential global positioning system, GPS. The magnetic field measurements were adjusted for layback.

The observed range in the magnetic field was 775nT. The shading observed in Plate 2 and Figures represents the gradient in the magnetic field density.

Seismic reflection. In May 2005, Earthworks used an Edgetech 424 chirp sub-bottom profiler.

The frequency of the chirp signal used was 4 to 24 kHz. Additional measurements were made with an Edgetech 512i in August, 2005. The frequency of these measurements was lower – 500Hz to 6.0kHz. The objective of the lower-frequency measurements was to test the higher frequency results.

The seismic reflection measurements were interpreted in two ways: (a) determination of diffractions due to the pipes, and (b) delineation of the pipe trench by denoting the disruption of naturally-deposited, sedimentary strata in the area-of-investigation.

Earthworks conducted the interpretation of the seismic-reflection results independently of the interpretation magnetic field density measurements. The agreement, or disagreement, of the independent interpretation represents an estimate of accuracy in the locations.

Table 3. Equipment used in geophysical surveys.

Survey Equipment Frequency sweep Magnetic field density Marine Magnetics Sea Spy Seismic reflection Edgetech 424 4.0-24.0kHz Edgetech 512i 0.5-6.0kHz

4. Results

Figure 2 shows the location of two water pipes based on all of the measurements: the magnetometer measurements of magnetic field density and the sub-bottom seismic measurement of the pipe trench and top-of-pipe. Tables 4 and 5 list the estimated trajectories of the northern and southern pipes, respectively. The error in these estimates is +-25ft.

The values in magnetic field density observed in the Anchorage are 52,400 to 53,200 nT. The range is 800 nT.

Note that observed trajectory for each pipe is 25 to 100ft north of the USACE planimetrics lines representing the water pipes.

Observe in Figures 2 and 3 that two other pipe trenches south the water pipes and north of the Verrazano Narrows Bridge exhibit a distinct trajectory across the Anchorage Channel in S-AN-1.

The USACE did not charge Earthworks with more detailed measurements of these trenches and pipes.

Table 4. Observed locations of the northern water pipe in New Jersey State Plane. Estimated error is in easting and northing is +-25ft.

Easting Northing 614,633.5 656,872.9 615,038.6 656,724.5 615,431.7 656,605.8 615,796.0 656,489.6 616,050.6 656,407.1 616,883.9 656,152.4

Table 5. Observed locations of the southern water pipe in New Jersey State Plane. Estimated error in easting and northing is +-25ft.

Easting Northing 615,602.1 653,107.7 616,282.3 653,100.7 616,644.0 653,126.9 616,994.3 653,133.5 617,354.3 653,135.2 617,664.0 653,136.6

Figure 3 shows the results solely based on the seismic reflection. Figure 4 shows the picks from two long lines run on either side of the axis of the Anchorage Channel. Figures 5 through 8 show examples of the seismic results. Figure 5 is a long line showing the water pipes and the two utility trench in the south. Figure 6 shows the seismic section across the northern water pipe. Figures 6 and 7 show seismic sections across the southern water pipe.

Figures 9 through 12 show the detailed results in the neighborhood of the northern pipe. Figure 9 shows the complete results. Figure 10 shows the shaded relief map of the magnetic field density.

Figures 11 and 12 show the interpretation of the seismic results. Figure 11 shows the disrupted, naturally-deposited, sedimentary strata. The disrupted layers indicate the pipe trench. Figure 12 shows the picked reflections from the top of the water pipe in the north.

Figures 13 through 16 show the detailed results in the neighborhood of the southern pipe. Figure 13 shows the complete results. Figure 14 shows the shaded relief map of the magnetic field density. Figures 15 and 16 show the interpretation of the seismic results. Figure 15 shows the disrupted, naturally-deposited, sedimentary strata. The disrupted layers indicate the pipe trench.

Figure 16 shows the picked reflections from the top of the water pipe in the south.

Figure 2. Observed locations for northern and southern water pipes in S-AN-1 in the Anchorage Channel.

Figure 3. Location of the two water pipes from seismic results.

Figure 4. Seismic picks on two long lines acquired in Anchorage channel. Pipe crossing A is the northern water pipe. Pipe crossing B is the southern water pipe. Pipe crossing C is the ConEd power cable conduit.

Pipe crossing D are four 24” gas pipelines.

Figure 5. First derivative of the seismic section along a long line in the Anchorage channel.

Water pipe Water pipe Gas pipelines

Cables

North South

Figure 6. First derivative of a seismic section containing the northern water pipe.

Water pipe

North South

Figure 7. First derivative of a seismic section across the trench containing the southern water pipe.

Water pipe North South

Figure 8. Seismic section in wiggle mode across the trench containing the southern water pipe.

Water pipe North South

Figure 9. Northern pipe location based on seismic picks overlain on magnetic field density shaded relief map.

Figure 10. Shaded relief map emphasizing the gradient in the magnetic field density for the northern water pipe.

Figure 11. Location of northern water pipe trench based on interruption of continuous sedimentary strata in the Anchorage channel. The green lines are seismic track lines in which continuous layers have been interpreted.

Figure 12. Location of seismic picks of top-of-pipe for the northern water pipe. .

Figure 13. Southern pipe location based on seismic picks overlain on magnetic field density shaded relief map.

Figure 14. Shaded relief map emphasizing the gradient in the magnetic field density for the southern water pipe.

Figure 15. Location of southern water pipe trench based on interruption of continuous sedimentary strata in the Anchorage channel. The green lines are seismic track lines in which continuous layers have been interpreted.

Figure 16. Location of seismic picks of top-of-pipe for the northern water pipe. .

5. Conclusions

(1) Earthworks has mapped two water pipes in Contract Area S-AN-1 in the Anchorage Channel just north of the Verrazano Narrows Bridge.

(2) The estimated error in the locations is +-25ft.

(3) The observed locations are based on (a) magnetometer measurement of magnetic field density and (b) independent sub-bottom measurement of seismic reflectivity.

(4) Detailed measurements were made in the neighborhood around the pipes.

(5) The two sets of measurements agree very well; that is, within +-15ft.

(6) Each of the observed pipe trajectories is 25 to 100ft north of the USACE planimetrics representing the pipe crossings in the channel.

(7) Earthworks observed two other pipe trenches south the water pipes and north of the

Verrazano Narrows Bridge. These pipes exhibit a distinct trajectory across the Anchorage Channel in S-AN-1.

Appendix I.

Comments from USACE, District of New York on draft

Ben Baker on November 16, 2005:

1. There is no sub-bottom data included in the report or on the plates. There should be some examples of the interpreted and un-interpreted data showing the water line trenches in terms of truncated strata etc.

2. Any vertical data in terms of the top of the pipes that can be provided would also be beneficial.

Earthworks response on November 29, 2005:

1. The sub-bottom results are displayed in Figures 5 through 8.

2. Earthworks will produce an extended appendix on the elevation of the water pipes and location of the utility crossings.

Appendix II.

11”x17” versions of the oversize plates