Mapping of the protective plates AD in Port Jersey under the S-AN-UC.PDF

Great Lakes Dredge & Dock Company, LLC Staten Island Office 2705 Richmond Terrace Staten Island, NY, 10303

Contract #W912DS-16-C-0004, GLDD #15614 Mapping of the protective plates after dredging in Port Jersey under the S-AN-UC

FINAL September 22, 2016

27 GLEN ROAD, NORTH ENTRANCE

SANDY HOOK, CONNECTICUT 06482

P.O. BOX 178, NEWTOWN, CT 06470

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

www.e4sciences.com ii

All interpretations are opinions based on inferences from seismic 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.

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Executive Summary

From November 2011 to August 2012, 430 steel plates were placed above the Passaic Valley Sewerage Commission (PVSC) Tunnel in order to protect this valuable piece of infrastructure from harbor deepening and deep-draft navigation projects. In 2015, as part of the S-AN-UC dredging contract of the New York and New Jersey Harbor Deepening Project, the United States Army Corps of Engineers, New York District (USACE-NAN), contracted Great Lakes Dredge & Dock (GLDD) to dredge the accumulated sediments in the area of Port Jersey, above and around the steel plates, to an elevation of -50ft USACE MLW (NGVD29 at Sandy Hook).

In 2016, GLDD assigned e4sciences (e4) to measure and map the positioning of the existing protective plates covering the trajectory of the PVSC sewer tunnel crossing Port Jersey both before and after dredging. This report presents the after-dredging measurements. e4 performed the surveys on September 09, 2016. GLDD performed dredging operations between August 17 and September 01. The USACE approved the area to grade on September 07, 2016 with an after-dredging bathymetric survey.

e4sciences found that the after-dredging survey is consistent with the before-dredging survey.

None of the plates are above -52.0ft MLW. None of the exposed plates lie on top of each other.

More than 50 plates may have subsided within the error of the measurement that is ±0.2ft. e4 interpretation of the before and after survey data indicates that the dredging did not disturb the plates.

The dredging operations between August and September removed sediments from the top of the plates. A few plates that were clear before dredging now have a thin layer of sediment cover.

Plates 268 to 300 are partially covered by a thin layer of sediments. A thicker layer of sediments covers plates 301 to 430. This layer thickness is between 1 and 2ft. These sediments appear to be a mix of black silt and clean sediments. No sediments were sampled. The seismic shows evidence of the plates at or below -52ft MLW.

Other areas around the plates were also dredged to an elevation below -50ft MLW. The elevations from the USACE-NAN survey are in agreement with the e4sciences data.

There is no evidence of dredging above the New York Bay Shaft. There is an object at the Global Marine Terminal berth bottom area that was not present during the before-dredging survey.

e4sciences recommends monitoring the sedimentation in this area. A ridge created by the plates may have formed an attractor for sediment deposition, thus increasing the sediment accumulation in this area. Caution needs to be taken during future maintenance dredging in this area.

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Table of contents Disclaimer ......................................................................................................................................... ii Executive Summary ........................................................................................................................ iii Table of contents ............................................................................................................................. iv List of figures .................................................................................................................................. iv List of tables ..................................................................................................................................... v List of plates ..................................................................................................................................... v

1. Introduction

2. Scope of work

3. Methodology

3.1 Task 1: Bathymetry

3.2 Task 2: Side-scan orthosonographs

3.2.1 Side-scan processing

3.3 Task 3: Sub-bottom reflection seismology

3.3.1 Sub-bottom seismic processing

3.4 Task 5: Integration

3.4.1 Uncertainty

4. Results

4.1 Evaluation of USACE multibeam bathymetry

4.2 After dredge survey results

4.3 Plates 226 to 350

4.4 Plates 351 to 430

5. Conclusions Appendix I. Plates 001 to 225

A-1 Plates 001 to 100 A-2 Plates 101 to 225

Appendix II. 11x17 version of plates

List of figures Figure 1. Location map Figure 2. Sub-bottom tracklines along the trajectory of the plates Figure 3. USACE multibeam bathymetry September 6, 2016 (#4520B) Figure 4. USACE multibeam bathymetry June 2016 (#4500) Figure 5. Bathymetry difference map Figure 6. Side-scan orthosonograph insonified from the northeast Figure 7. Side-scan orthosonograph insonified from the southwest Figure 8. Anomaly at Global Marine Terminal Figure 9. Plates 226 – 350: USACE bathymetry comparison Figure 10. Plates 226 – 350: USACE bathymetry difference map Figure 11. Plates 226 – 350: side-scan orthosonograph after versus before dredging Figure 12. Plates 226 – 350: side-scan orthosonograph after versus before dredging Figure 13. Plates 251 – 259: sub-bottom comparison after versus before dredging Figure 14. Plates 261 – 270: sub-bottom comparison after versus before dredging Figure 15. Plates 271 – 280: sub-bottom comparison after versus before dredging Figure 16. Plates 281 – 290: sub-bottom comparison after versus before dredging Figure 17. Plates 291 – 300: sub-bottom comparison after versus before dredging Figure 18. Plates 301 – 310: sub-bottom comparison after versus before dredging Figure 19. Plates 311 – 320: sub-bottom comparison after versus before dredging Figure 20. Plates 321 – 330: sub-bottom comparison after versus before dredging v

Figure 21. Plates 331 – 340: sub-bottom comparison after versus before dredging Figure 22. Plates 341 – 350: sub-bottom comparison after versus before dredging Figure 23. Plates 351 – 430: USACE bathymetry comparison Figure 24. Plates 351 – 430: USACE bathymetry difference Figure 25. Plates 351 – 430: side-scan orthosonograph after versus before dredging Figure 26. Plates 351 – 430: side-scan orthosonograph after versus before dredging Figure 27. Plates 351 – 360: sub-bottom comparison after versus before dredging Figure 28. Plates 361 – 370: sub-bottom comparison after versus before dredging Figure 29. Plates 371 – 380: sub-bottom comparison after versus before dredging Figure 30. Plates 381 – 390: sub-bottom comparison after versus before dredging Figure 31. Plates 391 – 400: sub-bottom comparison after versus before dredging Figure 32. Plates 401 – 410: sub-bottom comparison after versus before dredging Figure 33. Plates 411 – 420: sub-bottom comparison after versus before dredging Figure 34. Plates 421 – 428 and Plate 430: sub-bottom comparison after versus before dredging 43 Figure A-1. Plates 001 – 100: side-scan orthosonograph after versus before dredging Figure A-2. Plates 001 – 100: side-scan orthosonograph after versus before dredging Figure A-3. Plates 101 – 225: side-scan orthosonograph after versus before dredging Figure A-4. Plates 101 – 225: side-scan orthosonograph after versus before dredging Figure A-5. Plate 126 displacement

List of tables Table 1. Project chronology

List of plates

Plate 01. Location map Plate 02. USACE Bathymetries 2016 Plate 03. USACE difference maps Plate 04. Side-scan orthosonograph 2016 from northeast Plate 05. Side-scan orthosonograph 2016 from southwest Plate 06. Seismic cross sections Plate 07. Seismic cross sections

1. Introduction

From November 2011 to August 2012, 430 steel plates were placed above the Passaic Valley Sewerage Commission (PVSC) Tunnel in order to protect this valuable piece of infrastructure from harbor deepening and deep-draft navigation projects. In 2015, as part of the S-AN-UC dredging contract of the New York and New Jersey Harbor Deepening Project, the United States Army Corps of Engineers, New York District (USACE-NAN), contracted Great Lakes Dredge & Dock (GLDD) to dredge the accumulated sediments in the area of Port Jersey, above and around the steel plates, to an elevation of -50ft USACE MLW (NGVD29 at Sandy Hook).

In 2016, GLDD assigned e4sciences (e4) to measure and map the positioning of the existing protective plates covering the trajectory of the PVSC sewer tunnel crossing Port Jersey both before and after dredging. This report presents the after-dredging measurements. e4 performed the surveys on September 09, 2016. GLDD performed dredging operations between August 17 and September 01, 2016. The USACE approved the area to grade on September 07, 2016 with an after-dredging bathymetric survey.

Figure 1 is a location map. This map includes (a) the as-built template (measured by Weeks Marine Inc.) and envelope for the plates, (b) the outline of the no-spud zone around the plates, (c) the -50ft contour from the June 2016 USACE-NAN survey branch multibeam bathymetry, and

(d) the location of the New York Bay shaft.

Table 1 lists the chronology of the project through the before and after dredging mapping.

Table 1. Project chronology.

Task Start Complete yyyy.mm.dd yyyy.mm.dd 1 Notice to proceed 2016.05.17 2 Sub-bottom reflection acquisition before dredging 2016.05.19 2016.06.06 3 Side-scan acquisition before dredging 2016.05.19 2016.06.09 4 Magnetometer acquisition before dredging 2016.06.08 2016.06.09 5 Sub-bottom reflection processing before dredging 2016.05.23 2016.07.15 6 Side-scan processing before dredging 2016.05.23 2016.05.31 7 Magnetometer processing before dredging 2016.06.14 2016.06.17 8 Report for before dredging survey 2016.07.07 2016.07.29 9 Sub-bottom reflection acquisition after dredging 2016.09.09 2016.09.09

10 Side-scan acquisition after dredging 2016.09.09 2016.09.09 11 Sub-bottom reflection processing after dredging 2016.09.09 2016.09.16 12 Side-scan processing after dredging 2016.09.09 2016.09.16 13 Report for after dredging survey 2016.09.14

Figure 1. Location map including the (a) as-built template and envelope for steel plates in white, (b) no-spud zone around the plates in red, and (c) -50ft contour from the 2016 USACE-NAN multibeam bathymetry in gray, and (d) the New York Bay shaft location in red.

2. Scope of work

GLDD assigned e4ciences to perform hydrographic and geophysical surveys before and after dredging in Port Jersey as part of the S-AN-UC contract with the USACE-NAN. e4sciences is familiar with the site and qualified to perform this role. e4sciences was the third party surveyor responsible for Quality Assurance for the USACE-NAN during the original contract with Weeks Marine Inc. to place the steel plates from 2011 to 2012.

e4sciences performed sub-bottom reflection seismology, side-scan orthosonographs, and magnetic field measurements to map the plates exposed in the water column and beneath the sediments before dredging. The seismic signals penetrated the sediment and reflected off the top of the plates to locate their position in xyz. Successive profiles of each plate determined their relative and absolute locations.

The error in the absolute locations of the plates was determined by comparing the orthosonographs and multibeam in the areas where the plates were exposed right after construction in 2012 with those acquired before dredging operations in 2016. e4sciences expected the horizontal error to be driven by the error of the RTK positioning elements and geometric spreading in the measurements.

e4 was not assigned to sample sediments. The speed of sound in the sediment was estimated from previous data.

e4sciences’ Before Dredging (BD) survey results were made available to the USACE.

e4sciences performed sub-bottom reflection seismology, side-scan orthosonographs to map the plates exposed in the water column and beneath the sediments for the After Dredging (AD) survey. e4sciences used the same equipment and methods in the AD survey as the BD survey.

The preconstruction BD survey was compared to the AD survey in order to determine if GLDD disturbed any plates in the course of the dredging process.

3. Methodology

The horizontal reference frame is New Jersey State Plane, NAD83 (U.S. Survey Feet). The vertical datum is USACE MLW in NGVD29 at Sandy Hook. All elevations show the negative sign where elevations are referenced to USACE MLW. Measurements are made in feet and tenths of feet.

e4sciences employed its geophysical research vessel Time and Tide and its tender for all marine surveys. The Time and Tide is 60ft in length and fully equipped for geophysical exploration in shallow waters.

3.1 Task 1: Bathymetry

e4sciences analyzed and compared the USACE multibeam bathymetry surveys from before and after dredging operations, that is June and September 2016.

e4sciences acquired multibeam bathymetry together with the side-scan sonar on September 09, 2016. The multibeam bathymetry was not part of the scope of work. e4 used the bathymetry as a back check with the other measurements to reduce the uncertainty for the mapping and imaging of the plates.

3.2 Task 2: Side-scan orthosonographs

e4 used an Edgetech 6205 at 550kHz to acquire the data and produce the orthosonographs on September 09, 2016. e4 acquired the data along the tunnel trajectory. The side-scan sonar transmits ultrasonic waves obliquely into the water and measures the amplitude of the backscatter from the bottom as a function of range. The reflectivity is a function of the bottom roughness and the sediment acoustic properties. The e4 proprietary processing produces two independent orthosonographs: one from the northeast and one from the southwest. These reflectivity images produce a high-definition picture of the structures on the bottom. These images are also the best means to map debris on the bottom.

The side-scan images produced orthosonographs, seamless aerial-photograph-like images of the surface sediments in the channel. The survey produced 100% coverage with 200% redundancy of the area of investigation. e4sciences acquired two independent orthosonographs insonified from two directions, sufficient to constitute the 200% redundancy. Orthosonographs are seamless aerial-photograph-like images that are insonified from one direction only.

The horizontal accuracy in the side-scan orthosonograph is ±2ft. The orthosonograph resolution is ±0.3ft

3.2.1 Side-scan processing

e4 processed all of the side-scan data with a 0.3ft resolution – that is an order of resolution better than achieved by standard processing. e4 produced georeferenced images, illuminated from one direction that can be used with any geospatial interpretation software, such as ArcGIS or AutoCAD.

e4’s proprietary method for side-scan orthosonographs produces images that present high acoustic reflectivity as bright (white) and low reflectivity areas as dark (dark brown). This differs from the common use of side-scan images in strip charts, which often invert the colors. e4’s method produces images that are more intuitive. Acoustic shadows (areas of no reflection) are also easier to detect visually in e4’s orthosonograph images as a result of this processing.

The processing applies a time varying gain (TVG) for relative amplitude balancing based on the location of the project. All of the GeoTIFF files are created with the same TVG values throughout the project – this allows for a direct comparison of data. The mosaics are made as 8-bit images with a spatial resolution of 0.3ft. The final step applies a standard sepia color scale to the mosaic images to create the GeoTIFF. The values of the TVG for the mosaic are specific for the Port Jersey region. e4 applied the same processing scheme and values as in the data acquired in 2012.

This allows one to one comparison of both datasets.

These GeoTIFFs having higher spatial resolution (0.3ft) provide more information per area than would higher dynamic range mosaics at standard resolution of 3ft.

3.3 Task 3: Sub-bottom reflection seismology

e4 used an Edgetech 512i sub-bottom profiler to acquire the seismic data. From the before-dredging survey, the 1-10kHz chirp was most successful in penetrating through the recent sediment and black silt deposits that have accumulated on top of the plates.

e4 imaged the plates and sub-surface with 1-10kHz frequency set during the after-dredging survey. Sub-bottom profiling works similarly to single-beam bathymetry. The much lower frequency seismic waves, however, penetrate the mudline and reflect off the strata in the subsurface. e4 acquired the sub-bottom data with the same instruments and parameters as the sub-bottom data from 2012, and before-dredging surveys.

Figure 2 plots the sub-bottom tracklines. e4 acquired a total of 21 seismic lines, all of them along the trajectory of the tunnel.

The horizontal accuracy in the reflection seismology is ±1.5ft. The vertical accuracy is ±1ft for every 10ft of overburden.

3.3.1 Sub-bottom seismic processing

e4 has developed a proprietary set of protocols for processing high-frequency, shallow water, reflection seismology for determination of sediments and rock in harbors.1 e4 filters every line.

The processing generates six different images for every line. The six images facilitate interpretation of the data.

The standard format of representing sub-bottom seismic data is the raw format, that is, the envelope of the chirp signal. The chirp signal has a time-varying frequency. e4’s proprietary

1 William Murphy III, W. Bruce Ward, Beckett Boyd, Gary Fleming, William Murphy IV, Richard Nolen-Hoeksema, Matthew Art, and Daniel A. Rosales, High-resolution shallow geophysics and geology in the Hudson-Raritan Estuary Ecosystem Restoration, New Jersey, The Leading Edge, February 2011, Vol. 30, No. 2: pp. 182-190.

processing allows the generation of the real and imaginary components of the time-varying frequency signal. The real analytical component of the chirp data allows processing of the images using wave-equation techniques. The data is migrated to depth with an initial constant velocity model derived from field water velocity measurements.

The navigation of the seismic data is processed using Kalman filters. The dGPS position is 1Hz frequency. The data has a 0.25Hz repetition rate. The Kalman filter interpolates the spatial location data using the sensor positioning, the speed of the boat, and the heading. The average trace spacing for the seismic lines is 0.5ft.

e4 measures the water column and each sediment type to accurately determine the density and the speed of sound in each medium.

3.4 Task 5: Integration

e4 uses redundant measurements to quantify all results. Each survey is calibrated in the local area with a proprietary test. All measurements are processed independently and integrated into a single geo-reference frame after processing. Redundant measurements (repeat lines or scans) quantify the precision and delineate uncertainty in the measurements. Repeat lines are not always delivered to the client, but are available for review upon request. The orthosonographs provide the detailed images beyond the bathymetry. e4 produced a series of cross sections from the sub-bottom reflection seismology. e4 used its multibeam bathymetry to support the interpretation of the other measurements.

3.4.1 Uncertainty

High-definition mapping determines the horizontal and vertical displacement of the plates relative to the locations in the as-built drawings. The challenge in mapping the after-dredging configuration of the plates is to image the plates under a variable thickness of silt. The combination of side-scan orthosonographs and sub-bottom seismic reflection cross sections provide repeatable accuracy of ±0.3ft vertically and ±0.3ft horizontally at best.

We compare the AD survey with the (1) BD survey, (2) existing as-built drawings, (3) post-construction imaging, and (4) side-scan images taken after the Hurricane Sandy event.

Our strategy for this report is to compare the before-dredging results with the after-dredging survey configuration. Please note that 0.3ft horizontal and 0.3ft vertical error exist in both the before-dredging and after-dredging investigations.

It is crucial to determine if at any time (a) the elevation of the plates reaches above -52.0ft USACE MLW or (b) the plates have been horizontally displaced more than 1ft. The displacement along the tunnel trajectory is limited to 4inches and the displacement normal to the tunnel trajectory allows for several feet of displacement, therefore 1ft is adequate to determine the horizontal displacement. The vertical measurement of the top of buried plates is the difficult goal to achieve.

Method applied Sub-bottom reflection seismology (1-10kHz) Penetration ~10ft Horizontal accuracy ~ ±1.5ft with dGPS (3ft) Vertical accuracy ~ ±0.3ft Vertical precision ~ ±0.2ft

Side-scan orthosonograph Penetration ~0.1ft Horizontal accuracy ~ ±0.3ft Vertical accuracy ~ n.a.

By correlating the measurements, e4 estimates that:

Penetration ~10ft Horizontal accuracy ~ ±1.5ft (3ft) Vertical accuracy ~ ±0.3ft Vertical precision ~ ±0.2ft

Figure 2. Sub-bottom tracklines along the trajectory of the plates.

4. Results

All data presented in the report are located in the coordinate system of NAD83 New Jersey State Plane in U.S. Survey Feet and the vertical datum USACE MLW NGVD29 at Sandy Hook.

4.1 Evaluation of USACE multibeam bathymetry

e4sciences compared USACE after dredged bathymetry acquired on September 06, 2016 (#4520B) minimum with the before dredge survey, that is the June 2016 (#4500) minimum.

Figure 3 is the USACE multibeam bathymetry over the plates for September 2016; the area covered during this survey is between Plates 250 to 430. Figure 4 is the USACE multibeam bathymetry over the plates for June 2016; both bathymetry maps are in a 3x3ft grid minimum.

This is the agreed bathymetry specification for dredging approval. Note that the color map shows all elevations above -50.0ft as red, elevations between -52ft to -50.0ft are in the green spectrum, and elevations deeper than -52.0ft in the blue spectrum.

Figure 5 shows the difference map of USACE bathymetries between September 2016 and June 2016. The difference maps is between the minimum surveys, and is 3x3ft grids.

4.2 After dredge survey results

The first result requested by GLDD was to image the water bottom with side-scan orthosonographs. The side-scan was followed by sub-bottom seismic imaging.

e4sciences measured the channel bottom reflectivity following the center line of the tunnel trajectory. Figure 6 shows the May 2016 orthosonograph insonified from the northeast with the data acquired along the trajectory of the tunnel. Figure 7 shows the May 2016 orthosonograph insonified from the southwest with the data acquired along the trajectory of the channel.

The dredging operations occurred between Plates 300 to 430. The USACE bathymetry after dredging covers this area alone. Sections 4.3 and 4.4 present the findings from the e4sciences after-dredging survey above the plates. Appendix I show the results from e4sciences after-dredging survey for Plates 001 to 225.

e4sciences found one anomaly at the Global Marine Terminal area that was not present during the before-dredging survey. Figure 8 shows this anomaly. The object is present in both the side-scan orthosonograph and the e4 bathymetric measurement. The size of the anomaly is approximately 10ft and its shallowest elevation is at -50.5ft. This anomaly is outside the navigation channel.

Figure 3. USACE multibeam bathymetry September 6, 2016 (#4520B) minimum, 3x3ft grid.

Figure 4. USACE multibeam bathymetry June 2016 (#4500) minimum, 3x3ft grid.

Figure 5. Bathymetry difference map USACE September (#4520B) minus June (#4500) 2016.

Figure 6. Side-scan orthosonograph insonified from the northeast. Data acquired on September 09, 2016.

Figure 7. Side-scan orthosonograph insonified from the southwest. Data acquired September 09, 2016.

Figure 8. Anomaly at Global Marine Terminal. This might be a dropped container in the area. The anomaly is approximately 10ft long and not shallower than -50.5ft MLW.

4.3 Plates 226 to 350

Plates 226 to 267 are exposed. A layer of thin sediments partially covers Plates 268 to 281. Plates 282 to 300 are partially exposed towards the northeast boundary. The side-scan orthosonograph shows dredging marks starting at Plate 308. There are no high spots shallower than -50.0ft within the vertical precision of the USACE bathymetry. There is a remaining 1-2ft sediment layer covering the plates. There is no evidence of plates exposed or moved in this area.

Figure 9 is a close-up of the USACE bathymetries September 06, 2016 (#4520B) and June 2016 (#4500). Figure 10 is the zoom-in of the bathymetry difference map between USACE data from September minus June 2016.

Figure 11 plots a comparison of the side-scan orthosonograph between September and May 2016.

The side-scan from September and May are both insonified from the northeast.

Figure 12 plots a comparison of the side-scan orthosonograph between September and May 2016.

The side-scan from September and May are both insonified from the southwest.

Figures 13 to 21 compares the sub-bottom seismic investigation from the before-dredging and after-dredging surveys. After sediment removal the signal from the plates is clearer and stronger.

This allows for an identification of the top of the plates. All the plates appear at the same elevation as in the before-dredging survey. The solid cyan and blue lines represent the two bathymetries on this report, that is, the September and June 2016 USACE bathymetries, respectively. The two solid red lines correspond to this project dredging depth and the plate’s as-built depth, that is -50ft and -52ft MLW.

Figure 9. Plates 226 – 350: USACE bathymetry comparison, (left) September 2016 bathymetry (#4520B), after dredge; (right) June 2016 bathymetry (#4500), before dredge.

Figure 10. Plates 226 – 350: USACE bathymetry difference map September 2016 (#4520B) minus June 2016 (#4500).

Figure 11. Plates 226 – 350: comparison of side-scan orthosonograph insonified from the northeast between (left) September 2016, after dredge and (right) June 2016, before dredge.

Figure 12. Plates 226 – 350: comparison of side-scan orthosonograph insonified from the southwest between (left) September 2016, after dredge and (right) June 2016, before dredge.

Figure 13. Plates 251 – 259: sub-bottom comparison after (above) versus before (below) dredging.

Figure 14. Plates 261 – 270: sub-bottom comparison after (above) versus before (below) dredging.

Figure 15. Plates 271 – 280: sub-bottom comparison after (above) versus before (below) dredging.

Figure 16. Plates 281 – 290: sub-bottom comparison after (above) versus before (below) dredging.

Figure 17. Plates 291 – 300: sub-bottom comparison after (above) versus before (below) dredging.

Figure 18. Plates 301 – 310: sub-bottom comparison after (above) versus before (below) dredging. The layer of sediment is starting to be within the seismic resolution at Plate 308.

Figure 19. Plates 311 – 320: sub-bottom comparison after (above) versus before (below) dredging. The layer of sediment thickens to 1ft. One foot of sediments has been removed in this area on top of the plates.

Figure 20. Plates 321 – 330: sub-bottom comparison after (above) versus before (below) dredging. More than one foot of sediment has been removed from the top of the plates.

Figure 21. Plates 331 – 340: sub-bottom comparison after (above) versus before (below) dredging. More than one foot of sediment has been removed from the top of the plates.

Figure 22. Plates 341 – 350: sub-bottom comparison after (above) versus before (below) dredging. More than two feet of sediment has been removed from the top of the plates.

4.4 Plates 351 to 430

A thin sediment layer remains on top of all Plates 351 to 430. This sediment layer varies in thickness from 1 to 2ft. The side-scan orthosonograph shows dredging marks throughout this area. The side-scan orthosonograph and the seismic show an area of sandy sediments along Plates 367 to 370, as evidence by a light reflection from the side-scan and polarity reversal in the seismic image. There is a remaining 1 and 2ft sediment layer covering the plates. There is no evidence of plates exposed or moved in this area.

No sediments were sampled. Plate 430 is outside the channel on the slope.

Figure 23 is a close-up of the USACE bathymetries September 06, 2016 (#4520B) and June 2016 (#4500). Figure 24 is the zoom-in of the bathymetry difference map between USACE data from September minus June 2016.

Figure 25 plots a comparison of the side-scan orthosonograph between September and May 2016.

The side-scan from September and May are both insonified from the northeast.

Figure 26 plots a comparison of the side-scan orthosonograph between September and May 2016.

The side-scan from September and May are both insonified from the southwest.

Figures 27 to 34 compare the sub-bottom seismic investigation from the before-dredging and after-dredging surveys. After sediment removal the signal from the plates is clearer and stronger.

This allows for an easier identification of the top of the plates. All the plates appear at the same elevation as in the before-dredging survey, within the margin of error from the seismic measurement. The solid cyan and blue lines represent the two bathymetries on this report, that is, the September and June 2016 USACE bathymetries, respectively. The two solid red lines correspond to this project dredging depth and the plate’s as-built depth, that is -50ft and -52ft

MLW.

Figure 23. Plates 351 – 430: USACE bathymetry comparison, (left) September 2016 bathymetry (#4520B), after dredge; (right) June 2016 bathymetry (#4500), before dredge.

Figure 24. Plates 351 – 430: USACE bathymetry difference map September 2016 (#4520B) minus June 2016 (#4500).

Figure 25. Plates 351 – 430: comparison of side-scan orthosonograph insonified from the northeast between (left) September 2016, after dredge and (right) June 2016, before dredge.

Figure 26. Plates 351 – 430: comparison of side-scan orthosonograph insonified from the southwest between (left) September 2016, after dredge and (right) June 2016, before dredge.

Figure 27. Plates 351 – 360: sub-bottom comparison after (above) versus before (below) dredging. More than one foot of sediments remains on top of the plates. More than two feet has been removed from the top

Figure 28. Plates 361 – 370: sub-bottom comparison 2012 (above) versus 2016 (below). Sub-bottom comparison after (above) versus before (below) dredging. More than one foot of sediment remains on top of the plates. More than two feet has been removed from the top of the plates.

Figure 29. Plates 371 – 380: sub-bottom comparison after (above) versus before (below) dredging. More than one foot of sediment remains on top of the plates. More than two feet has been removed from the top

Figure 30. Plates 381 – 390: sub-bottom comparison after (above) versus before (below) dredging. More than one foot of sediment remains on top of the plates. More than two feet has been removed from the top

Figure 31. Plates 391 – 400: sub-bottom comparison after (above) versus before (below) dredging. More than one foot of sediment remains on top of the plates. More than two feet has been removed from the top of the plates. There is evidence of subsidence on the plates. The subsidence is within the margin of error.

Figure 32. Plates 401 – 410: sub-bottom comparison after (above) versus before (below) dredging. More than one foot of sediment remains on top of the plates. More than two feet has been removed from the top of the plates. There is evidence of subsidence on the plates. The subsidence is within the margin of error.

Figure 33. Plates 411 – 420: sub-bottom comparison after (above) versus before (below) dredging. More than one foot of sediment remains on top of the plates. More than two feet has been removed from the top of the plates. There is evidence of subsidence on the plates. The subsidence is within the margin of error.

Figure 34. Plates 421 – 428 and Plate 430: sub-bottom comparison after (above) versus before (below) dredging. More than one foot of sediment remains on top of the plates. More than two feet has been removed from the top of the plates. There is evidence of subsidence on the plates. The subsidence is within the margin of error.

5. Conclusions

From November 2011 to August 2012, 430 steel plates were placed above the Passaic Valley Sewerage Commission (PVSC) Tunnel in order to protect this valuable piece of infrastructure from harbor deepening and deep-draft navigation projects. In 2015, as part of the S-AN-UC dredging contract of the New York and New Jersey Harbor Deepening Project, the United States Army Corps of Engineers, New York District (USACE-NAN), contracted Great Lakes Dredge & Dock (GLDD) to dredge the accumulated sediments in the area of Port Jersey, above and around the steel plates, to an elevation of -50ft USACE MLW (NGVD29 at Sandy Hook).

In 2016, GLDD assigned e4sciences (e4) to measure and map the positioning of the existing protective plates covering the trajectory of the PVSC sewer tunnel crossing Port Jersey both before and after dredging. This report presents the after-dredging measurements. e4 performed the surveys on September 09, 2016. GLDD performed dredging operations between August 17 and September 1. The USACE approved the area to grade on September 7, 2016 with an after-dredging bathymetric survey.

1. e4sciences found that the after-dredging survey is consistent with the before-dredging survey.

2. None of the plates are above -52.0ft MLW.

3. None of the exposed plates lie on top of each other.

4. More than 50 plates may have subsided within the error of the measurement that is ±0.2ft.

5. e4 interpretation of the before and after survey data indicates that the dredging did not disturb the plates.

6. The dredging operations between August and September removed sediments from the top of the plates.

7. A few plates that were clear before dredging now have a thin layer of sediment cover. Plates

268 to 300 are partially covered by a thin layer of sediments.

8. A thicker layer of sediments covers plates 301 to 430. This layer thickness is between 1 and

2ft. These sediments appear to be a mix of black silt and clean sediments. No sediments were sampled.

9. The seismic shows evidence of the plates at or below -52ft MLW.

10. Other areas around the plates were also dredged to an elevation below -50ft MLW.

11. The elevations from the USACE-NAN survey are in agreement with the e4sciences data.

12. There is no evidence of dredging above the New York Bay Shaft.

13. There is an object at the Global Marine Terminal berth bottom area that was not present during the before-dredging survey.

14. e4sciences recommends monitoring the sedimentation in this area. A ridge created by the plates may have formed an attractor for sediment deposition, thus increasing the sediment accumulation in this area. Caution needs to be taken during future maintenance dredging in this area.

Appendix I.

Plates 001 - 225

A-1 Plates 001 to 100

Plates 001 to 100 are all outside the channel in the northern section of the area of investigation toward the Global Marine Terminal berth. Plates 001 to 030 are all under the new Global Marine Terminal berth. Figure 8 shows an anomaly in this area. The plates show no changes with respect to the before dredging surveys. The distribution of sediments covering the plates has changed.

Figure A-1 plots a comparison of the side-scan orthosonograph between September and May 2016. The side-scan from September and May are both insonified from the northeast.

Figure A-2 plots a comparison of the side-scan orthosonograph between September and May 2016. The side-scan from September and May are both insonified from the southwest.

Figure A-1. Plates 001 – 100: comparison of side-scan orthosonograph insonified from the northeast between (left) September 2016, after dredge and (right) June 2016, before dredge.

Figure A-2. Plates 001 – 100: comparison of side-scan orthosonograph insonified from the southwest between (left) September 2016, after dredge and (right) June 2016, before dredge.

A-2 Plates 101 to 225

Plates 101 to 105 are all outside the channel in the northern section of the area of investigation toward the Global Marine Terminal berth. Plates 101 to 105 are outside the channel. There are no changes on the plates with respect to the before dredge survey. The distribution of sediments covering the plates has changed. The amount of sediment covering the plates is less than 0.5ft thick.

Figure A-3 plots a comparison of the side-scan orthosonograph between September and May 2016. The side-scan from September and May are both insonified from the northeast.

Figure A-4 plots a comparison of the side-scan orthosonograph between September and May 2016. The side-scan from September and May are both insonified from the southwest.

Figure A-5 shows the displacement of Plate 126, the displacement is the same in the before and after dredging surveys. The displacement is between 3.5-5ft toward the southwest

Figure A-3. Plates 101 – 225: comparison of side-scan orthosonograph insonified from the northeast between (left) September 2016, after dredge and (right) June 2016, before dredge.

Figure A-4. Plates 101 – 225: comparison of side-scan orthosonograph insonified from the southwest between (left) September 2016, after dredge and (right) June 2016, before dredge.

Figure A-5. Plate 126 displacement from June 2016 side-scan orthosonograph insonified from the southwest.

Appendix II.

11x17 version of the plates

BBa

Military Ocean Terminal Bayonne, New Jersey

(MOTBY)

Global Marine Terminal

Channel Toe

Port Jersey Channel

E

E

E

E

E

E

E

E

E

E

E

E

N 668100 N 668100

N 668400 N 668400

N 668700 N 668700

N 669000 N 669000

N 669300 N 669300

N 669600 N 669600

Channel Toe

Port Jersey Channel

South of MOTBY Habitat Enhancement Site

Upper New York Bay

Military Ocean Terminal Bayonne, New Jersey

(MOTBY)

Port Jersey

SCALE

0' 75'

Plate 1: Location map with WMI as placed plates location planimetrics, no spud zone outline and USACE June 2016 bathymetry 50ft contour

Area of investigation in main map

Drawn by:

Approved by:

Date drawn: September 15, 2016

Contract #W912DS-16-C-0004, GLDD #15614 Mapping of the protective plates after dredging in Port Jersey under the S-AN-UC

New Jersey State Plane Feet Coordinate System North American Datum of 1983 (NAD83) 2015 High Resolution Orthophotography: NJ Office of Information Technology (NJOIT), Office of Geographic Information Systems (OGIS)

Location of PVSC New York Bay shaft as determined from previous geophysical investigation

No spud zone

USACE 2016 (#4500) bathymetry 50ft contour

Weeks Marine Inc.(WMI) as-built certified planimetrics Plates location

E

E

N 668160

N 668400

E

N 668640

E

E

E

N 668160

N 668400

N 668640

N 668880

N 669120

N 669360

E

E

E

E

N 668880

N 669120

Military Ocean Terminal Bayonne, New Jersey

(MOTBY)

Global Marine Terminal

Channel Toe

E

N 669360

E

E

E

Port Jersey Channel

Channel Toe

Port Jersey Channel

South of MOTBY Habitat Enhancement Site

Upper New York Bay

Military Ocean Terminal Bayonne, New Jersey

(MOTBY)

Port Jersey

E

E

N 668160

N 668400

E

N 668640

E

E

E

N 668160

N 668400

N 668640

N 668880

N 669120

N 669360

E

E

E

E

N 668880

N 669120

Military Ocean Terminal Bayonne, New Jersey

(MOTBY)

Global Marine Terminal

Channel Toe

E

N 669360

E

E

E

Port Jersey Channel

Channel Toe

SCALE

0' 60'

USACE September, 2016 bathymetric image (#4520B) elevation(ft)

Plate 2: USACE bathymetric images, September and June 2016

Area of investigation in main map

Drawn by:

Approved by:

Date drawn: September 15, 2016

Contract #W912DS-16-C-0004, GLDD #15614 Mapping of the protective plates after dredging in Port Jersey under the S-AN-UC

Outline of WMI as-built certified planimetrics Plates location

USACE June 2016 bathymetry (#4500) USACE September 2016 bathymetry (#4520B) 3x3 minimum

New Jersey State Plane Feet Coordinate System North American Datum of 1983 (NAD83) 2012 and 2015 High Resolution Orthophotography: NJ Office of Information Technology (NJOIT), Office of Geographic Information Systems (OGIS)

SCALE

0' 60'

USACE June, 2016 bathymetric image (#4500) elevation(ft)

E

N 668160

N 668400

E

N 668640

E

E

E

N 668160

N 668400

N 668640

N 668880

N 669120

N 669360

E

E

E

E

N 668880

N 669120

Military Ocean Terminal Bayonne, New Jersey

(MOTBY)

Global Marine Terminal

Channel Toe

E

N 669360

E

E

E

Port Jersey Channel

Channel Toe

Port Jersey Channel

South of MOTBY Habitat Enhancement Site

Upper New York Bay

Military Ocean Terminal Bayonne, New Jersey

(MOTBY)

Port Jersey

SCALE

0' 60'

USACE September 2016 minus June 2016 bathymetric difference image

Plate 3: USACE bathymetric difference image

Area of investigation in main map

Drawn by:

Approved by:

Date drawn: September 15, 2016

Contract #W912DS-16-C-0004, GLDD #15614 Mapping of the protective plates after dredging in Port Jersey under the S-AN-UC thickness (ft)

Outline of WMI as-built certified planimetrics Plates location

USACE June 2016 bathymetry (#4500) USACE September 2016 bathymetry (#4520B) 3x3 minimum

New Jersey State Plane Feet Coordinate System North American Datum of 1983 (NAD83) 2015 High Resolution Orthophotography: NJ Office of Information Technology (NJOIT), Office of Geographic Information Systems (OGIS)

E

N 668160

N 668400

E

N 668640

E

E

E

N 668160

N 668400

N 668640

N 668880

N 669120

N 669360

E

E

E

E

N 668880

N 669120

Military Ocean Terminal Bayonne, New Jersey

(MOTBY)

Global Marine Terminal

Channel Toe

E

N 669360

E

E

E

Port Jersey Channel

Channel Toe

Global Marine Terminal E609104 N669321 elevation -50.5ft

Port Jersey Channel

South of MOTBY Habitat Enhancement Site

Upper New York Bay

Military Ocean Terminal Bayonne, New Jersey

(MOTBY)

Port Jersey

E

E

N 668160

N 668400

E

N 668640

E

E

E

N 668160

N 668400

N 668640

N 668880

N 669120

N 669360

E

E

E

E

N 668880

N 669120

Military Ocean Terminal Bayonne, New Jersey

(MOTBY)

Global Marine Terminal

Channel Toe

E

N 669360

E

E

E

Port Jersey Channel

Channel Toe

Global Marine Terminal E609104 N669321 elevation -50.5ft

SCALE

0' 60'

SCALE

0' 60' e4sciences September 9, 2016 orthosonographs insonified from the northeast e4sciences May 25-June 7, 2016 orthosonograph insonified from the northeast

Plate 4: Orthosonographs illuminated from the northeast with outline of plates; sidescan data acquired by e4sciences September 9, 2016 and May 20-June 7, 2016

Area of investigation in main map

Drawn by:

Approved by:

Date drawn: September 15, 2016

Contract #W912DS-16-C-0004, GLDD #15614 Mapping of the protective plates after dredging in Port Jersey under the S-AN-UC

Travel direction of sidescan sonar signal (direction of illumination)

Outline of WMI as-built certified planimetrics Plates location

New Jersey State Plane Feet Coordinate System North American Datum of 1983 (NAD83) 2012 and 2015 High Resolution Orthophotography: NJ Office of Information Technology (NJOIT), Office of Geographic Information Systems (OGIS)

E

N 668160

N 668400

E

N 668640

E

E

E

N 668160

N 668400

N 668640

N 668880

N 669120

N 669360

E

E

E

E

N 668880

N 669120

Military Ocean Terminal Bayonne, New Jersey

(MOTBY)

Global Marine Terminal

Channel Toe

E

N 669360

E

E

E

Port Jersey Channel

Channel Toe

Port Jersey Channel

South of MOTBY Habitat Enhancement Site

Upper New York Bay

Military Ocean Terminal Bayonne, New Jersey

(MOTBY)

Port Jersey

E

E

N 668160

N 668400

E

N 668640

E

E

E

N 668160

N 668400

N 668640

N 668880

N 669120

N 669360

E

E

E

E

N 668880

N 669120

Military Ocean Terminal Bayonne, New Jersey

(MOTBY)

Global Marine Terminal

Channel Toe

E

N 669360

E

E

E

Port Jersey Channel

Channel Toe

SCALE

0' 60'

SCALE

0' 60' e4sciences September 9, 2016 orthosonographs insonified from the southwest e4sciences May 25, 2016 orthosonograph insonified from the southwest

Plate 5: Orthosonographs illuminated from the southwest with outline of plates; sidescan data acquired by e4sciences September 9, 2016 and May 20-June 7, 2016

Area of investigation in main map

Contract #W912DS-16-C-0004, GLDD #15614 Mapping of the protective plates after dredging in Port Jersey under the S-AN-UC

Drawn by:

Approved by:

Date drawn: September 15, 2016

Travel direction of sidescan sonar signal (direction of illumination)

Outline of WMI as-built certified planimetrics Plates location

New Jersey State Plane Feet Coordinate System North American Datum of 1983 (NAD83) 2012 and 2015 High Resolution Orthophotography: NJ Office of Information Technology (NJOIT), Office of Geographic Information Systems (OGIS)

Key

2016 Sep USACE bathymetry (#4502)

2016 June USACE bathymetry (#4500)

WMI as-built certified planimetrics Plate location

Dredge control depths

Plate 250Plate 249 Plate 260 Plate 270 Plate 271 Plate 272 Plate 274 Plate 275 Plate 277 Plate 279 Plate 289 Plate 290 Plate 291 Plate 292 Plate 293 Plate 294 Plate 295

Plate 299 Plate 300 Plate 301 Plate 302 Plate 303 Plate 304 Plate 305 Plate 306 Plate 307 Plate 308 Plate 309 Plate 310 Plate 320 Plate 328 Plate 340Plate 252 Plate 259 Plate 276 Plate 280

Plate 260 Plate 268 Plate 278 Plate 279 Plate 289 Plate 290 Plate 299

Plate 300 Plate 310 Plate 321 Plate 328 Plate 340Plate 252 Plate 259 Plate 276 Plate 280

-51

-55

-56

-52

-57

-49

-48

-47

-50

-54

-53

2016 Before Dredging Seismic Data (20160606_006000_015)

2016 After Dredging Seismic Data (20160909_020000_002)

USACE MLW

Elevation (feet)

*Note:

Elevation below mudline is approximate. No sediments were sampled. Elevations are from modeled seismic velocities for suspected sediments in the area.

2.5x vertical exaggeration

USACE MLW

Elevation (feet)

*Note:

Elevation below mudline is approximate. No sediments were sampled. Elevations are from modeled seismic velocities for suspected sediments in the area.

2.5x vertical exaggeration

USACE MLW

Elevation (feet)

*Note:

Elevation below mudline is approximate. No sediments were sampled. Elevations are from modeled seismic velocities for suspected sediments in the area.

2.5x vertical exaggeration

USACE MLW

Elevation (feet)

*Note:

Elevation below mudline is approximate. No sediments were sampled. Elevations are from modeled seismic velocities for suspected sediments in the area.

2.5x vertical exaggeration

0 5040302010 60 110100908070 150140130120 160 210200190180170 250240230220 260 310300290280270 340330320 350 380370360

0 5040302010 60 110100908070 150140130120 160 210200190180170 250240230220 260 310300290280270 340330320 350 380370360

-51

-55

-56

-52

-57

-49

-48

-47

-50

-54

-53

-51

-55

-56

-52

-57

-49

-48

-47

-50

-54

-53

-51

-55

-56

-52

-57

-49

-48

-47

-50

-54

-53

Military Ocean Terminal Bayonne, New Jersey

Port Jersey Channel

Global Marine Terminal

Channel Toe Channel Toe

SCALE

0' 300'

Displayed line

(MOTBY)

Drawn by:

Approved by:

Date: September 16th, 2016

Contract #W912DS-16-C-0004, GLDD #15614 Mapping of the protective plates after dredging in Port Jersey under the S-AN-UC

Plate 6: Seismic cross sections

2016 Seismic tracklines

Key

2016 Sep USACE bathymetry (#4520B)

2016 June USACE bathymetry (#4500)

WMI as-built certified planimetrics Plate location

Dredge control depths

Plate 350 Plate 360 Plate 369 Plate 380 Plate 377

Plate 391 Plate 392 Plate 393 Plate 394 Plate 400 Plate 401 Plate 409 Plate 420Plate 418 Plate 422

Plate 360 Plate 369 Plate 377 Plate 390

Plate 398 Plate 409 Plate 420Plate 418 Plate 422

2016 Pre Dredging Seismic Data (20160606_012000_002)

2016 After Dredging Seismic Data (20160909_020000_002)

2016 Before Dredging Seismic Data (20160606_006000_015)

USACE MLW

Elevation (feet)

*Note:

Elevation below mudline is approximate. No sediments were sampled. Elevations are from modeled seismic velocities for suspected sediments in the area.

2.5x vertical exaggeration

USACE MLW

Elevation (feet)

*Note:

Elevation below mudline is approximate. No sediments were sampled. Elevations are from modeled seismic velocities for suspected sediments in the area.

2.5x vertical exaggeration

USACE MLW

Elevation (feet)

*Note:

Elevation below mudline is approximate. No sediments were sampled. Elevations are from modeled seismic velocities for suspected sediments in the area.

2.5x vertical exaggeration

USACE MLW

Elevation (feet)

*Note:

Elevation below mudline is approximate. No sediments were sampled. Elevations are from modeled seismic velocities for suspected sediments in the area.

2.5x vertical exaggeration

390 440430420410400 450 500490480470460 540530520510 550 600590580570560 640630620610 650 700690680670660 730720710 740 770760750

390 440430420410400 450 500490480470460 540530520510 550 600590580570560 640630620610 650 700690680670660 730720710 740 770760750

-51

-55

-56

-52

-57

-49

-48

-47

-50

-54

-53

-51

-55

-56

-52

-57

-49

-48

-47

-50

-54

-53

-51

-55

-56

-52

-57

-49

-48

-47

-50

-54

-53

-51

-55

-56

-52

-57

-49

-48

-47

-50

-54

-53

Military Ocean Terminal Bayonne, New Jersey

Port Jersey Channel

Global Marine Terminal

Channel Toe Channel Toe

SCALE

0' 300'

Displayed line

2016 Seismic tracklines

Drawn by:

Approved by:

Date: September 16th, 2016

Contract #W912DS-16-C-0004, GLDD #15614 Mapping of the protective plates after dredging in Port Jersey under the S-AN-UC

Plate 7: Seismic cross sections