02_00_90_05_Geotechnical_Report_DEAL_QuadrantsReport_1and2.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 #W912DS-12-D-0002,Task Order #0015 Geophysical and Geotechnical investigation: Outfall design at Loch Arbour to Elberon, NJ under the Sandy Hook to Barnegat Beach Erosion Control Project

Quadrants 1 and 2 July 31, 2014

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 i

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.

5.0 Quadrant Reports

5.1 Quadrant Report 1. Outfalls from 45 to 42A

This report focuses on the southernmost quadrant from O utfalls 45 and 44 to Outfall 42A.

Figure 5.1-1 plots the orthosonographs insonified from east and west of outfalls 42A to 45. Figure 5.1-2 plots the bathymetric mapand Top-of-Tertiary map for outfalls 45 and 44 and 42A. Figure 5.1-3 plots the isopach map of Quaternary sand for outfalls 45 and 44 and 42A. Figure 5.1-4 plots the seismic cross section perpendicular to the shore in the vicinity of Outfall 44 and 45. Figure 5.1-5 plots the geological cross section perpendicular to the shore in the vicinity of Outfall 44 and 45.

Figure 5.1-1. Orthosonograph insonifed from east and west from Outfall 45 to 42A.

Figure 5.1-2. (Left) Bathymetric and topographic map with 5ft contours. (Right) Top of Tertiary map from Outfall 45 to 42A.

Figure 5.1-3. Isopach map of Quaternary sands from Outfall 45 to 42A.

Figure 5.1-4. Seismic cross section perpendicular to the shore. Near Outfall 40.

Figure 5.1-5. Geological cross section perpendicular to the shore. Near Outfall 40.

5.1.1 Outfalls 44 and 45

The next set focuses just on outfalls 44 and 45. Figure 5.1-6 plots the detailed orthosonograph vicinity of outfalls 44 and 45. Figure 5.1-7 shows the oblique aerial photographs of outfalls 44 and 45. Figure 5.1-8 shows existing conditions for outfalls 44 and 45. Figure 5.1-9 shows more existing conditions for outfalls 44 and 45. Figure 5.1-10 shows even more existing conditions for outfalls 44 and 45. Figure 5.1-11 shows more existing conditions for outfalls 44 and 45. Figure 5.1-12 plots a 3D imaging of Outfall 44 and 45.

Figure 5.1-6. Detailed orthosonograph of Outfall 45 and 44.

Figure 5.1-7. Aerial photographs of Outfalls 45 and 44.

Figure 5.1-8. Existing condition of Outfalls 45 and 44.

Figure 5.1-9. Existing condition of Outfalls 45 and 44.

Figure 5.1-10. Existing condition of Outfalls 45 and 44.

Figure 5.1-11. Existing condition of Outfalls 45 and 44.

Figure 5.1-12. 3D imaging of Outfalls 45 and 44.

5.1.2 Outfall 42A

Figure 5.1-13 plots the detailed orthosonograph vicinity of Outfall 42A. Figure 5.1-14 shows the oblique aerial photographs of 42A. Figure 5.1-15 shows existing conditions for Outfall 42A.

Figure 5.1-16 shows more existing conditions for Outfall 42A.

Figure 5.1-13. Detailed orthosonograph insonifed from east and west from Outfall 42A.

Figure 5.1-14. Aerial photographs of Outfall 42A.

Figure 5.1-15. Existing conditions for Outfall 42A, Neptune Avenue.

Figure 5.1-16. Existing conditions for Outfall 42A, Neptune Avenue.

5.2 Quadrant Report 2. Outfalls from 41 to 36

This report focuses on the southernmost quadrant from Outfalls 41 to 36.

Figure 5.2-1 plots the orthosonographs insonified from east and west for outfalls 41 to 36. Figure 5.2-2 plots the bathymetric map and Top of Tertiary map for Outfalls 41 to 36. Figure 5.3-3 plots the isopach map of Quaternary sand for outfalls 41 to 36. Figure 5.2-4 plots the seismic cross section perpendicular to the shore in the vicinity of outfalls 36 to 41. Figure 5.2-5 plots the geological cross section perpendicular to the shore in the vicinity of outfalls 41 to 36.

Table 5.2-1 shows the target list for the southernmost quadrant from outfalls 41 to 36. Target 1 is identified in Figures 5.2-1 to 5.2-3. Plate 8 also shows this target.

Table 5.2-1. Target list for outfalls 41 to 36.

Target number Area of Target Easting NJSP-ft

Northing NJSP-ft

Target description

1 36A and 36 634,924.8 516,988.3 Structure on side, possible pier.

634,993.8 516,970.4 634,945.3 516,783.7 634,876.4 516,801.6

Figure 5.2-1. Orthosonograph insonifed from east and west from outfall 41 to 36.

Figure 5.2-2. (Left) Bathymetric and topographic map with 5ft contours. (Right) Top of Tertiary map from outfal l 41 to 36.

Figure 5.2-3. Isopach map of Quaternary sands from outfall 41 to 36.

Figure 5.2-4. Seismic cross section perpendicular to shore. Near Outfall 36.

Figure 5.2-5. Geologic cross section perpendicular to shore. Near Outfall 36.

5.2.1 Outfall 41

The next set focuses just on Outfall 41. Figure 5.2-6 plots the detailed orthosonograph in the vicinity of Outfall 41. Figure 5.2-7 shows the oblique aerial photographs of Outfall 41. Figure 5.2-8 shows existing conditions for Outfall 41. Figure 5.2-9 shows more existing conditions for Outfall 41. Figure 5.1-10 plots an 3D imaging of Outfall 41.

Figure 5.2-6. Detailed orthosonograph of outfall 41.

Figure 5.2-7. Aerial photographs of outfalls 41 and 40. (Above) Looking west. Marine Place to the south.

Deal Esplanade to the north. (Below). Looking east.

Figure 5.2-8. Existing conditions of outfalls 41.

Figure 5.2-9. Existing conditions of outfall 41.

Figure 5.2-10. 3D imaging of outfall 41.

5.2.2 Outfall 40

Figure 5.2-11 plots the detailed orthosonograph vicinity of Outfall 40. Figure 5.2-12 shows the oblique aerial photographs of Outfall 40. Figure 5.2-13 shows existing conditions for Outfall 40.

Figure 5.2-14 plots 3D imaging of Outfall 40.

Figure 5.2-11. Detailed orthosonograph in the vicinity of outfall 40.

Figure 5.2-12. Aerial photographs of outfall 40.

Figure 5.2-13. Existing conditions of outfall 40.

Figure 5.2-14. 3D imaging of outfall 40.

5.2.3 Outfall 36A

Figure 5.2-15 plots the detailed orthosonograph vicinity of Outfall 36A. Figure 5.2-16 shows the oblique aerial photographs of Outfall 36A. Figure 5.2-17 shows existing conditions for Outfall 36A. Figure 5.2-18 shows more existing conditions for Outfall 36A. Figure 5.2-19 shows more existing conditions for Outfall 36A. Figure 5.2-20 plots 3D imaging of Outfall 36A.

Figure 5.2-15. Detailed orthosonograph in the vicinity of outfall 36A.

Figure 5.2-16. Aerial photographs of 36A.

Figure 5.2-17. Existing conditions of outfalls 36A.

Figure 5.2-18. Existing conditions of outfalls 36A.

Figure 5.2-19. Existing condition of outfalls 36A.

Figure 5.2-20. 3D imaging of outfall 36A.

Target 1

5.2.4 Outfall 36

Figure 5.2-21 plots the detailed orthosonograph vicinity of Outfall 36. Figure 5.2-22 shows the oblique aerial photographs of Outfall 36. Figure 5.2-23 shows existing conditions for Outfall 36.

Figure 5.2-24 shows more existing conditions for Outfall 36. Figure 5.2-25 shows more existing conditions for Outfall 36. Figure 5.2-26 shows more even existing conditions for Outfall 36.

Figure 5.2-27 plots 3D imaging of Outfall 36.

Figure 5.2-21. Detailed orthosonograph in the vicinity of outfall 36.

Figure 5.2-22. Aerial photographs of outfall 36.

Figure 5.2-23. Existing conditions of outfall 36.

Figure 5.2-24. Existing conditions of outfall 36.

Figure 5.2-25. Existing conditions of outfall 36.

Figure 5.2-26. Existing conditions of outfall 36.

Figure 5.2-27. 3D imaging of outfall 36.

6.0 Conclusions

1. This product consists of an overview and four reports on the four quadrants:

(1) outfalls 45 to 42A

(2) outfalls 41 to 36

(3) outfalls 36B to 29

(4) outfalls 28 through 19

2. The e4 team performed hydrographic surveys, sonar imaging, standard penetration test (SPT) borings, reflection seismology, photographic inventory, and land surveys in the nearshore, on the beach, and on the ridge.

3. The results produced surface topography and bathymetry, a Quaternary sand isopach map, a Top of Tertiary horizon, and maps of obstructions and debris.

4. The orthosonographs show sediment reflectivity, remnant piles, outfall debris, rip-rap, and large blocks.

5. The final bathymetry merges the USACE-NAN survey data, e4 single-beam results, and e4 multibeam-scanning results.

6. The field study combined land RTK survey, the LIDAR data, and professional data surveys to provide a complete topographic map of the area.

7. The orthosonographs and 3D imaging show that the groin heads are significantly larger than exposed subaerially. The orthosonographs reveal submarine exposures of the Tertiary sediments.

The orthosonographs show outfalls, sewer outfalls, and other obstructions to construction.

8. The sixteen borings (seven in the nearshore and nine on the beach) and the reflection seismology show that the stratigraphy consists of Quaternary sands overlying Tertiary sediments.

9. Subsurface in the project area consists of a relatively thin (~10ft) veneer of recent loose sands overlying an erosion surface in older more compact and stiff semi-consolidated Tertiary sediments.

10. The Quaternary sands consist mostly of Holocene beach deposits (Unit E). The average N-value in the Holocene sands measured 15.7. Pleistocene sands (Unit D) were encountered south of Poplar Brook. The average N-value in the Pleistocene sands measured 36.0. There is 1.5ft of clay near the base of the Pleistocene sands. Clay was not encountered in the Holocene sands.

11. The Tertiary sediments provide a bearing formation. The SPT borings penetrated three units (Unit C, Unit B, Unit A; younger to older) in the Tertiary. The average N-value in the three units measured 15.3, 19.4, and 16.8, respectively. The average plastic index measured in each of three units was 52.8, 19.7, and 3.0, respectively. The Tertiary sediments carry some gravel and fossils.

The three Tertiary units dip toward the southwest.

12. Unit A is exposed in highs on the seafloor. Units B and C have small irregular lithified rock areas less than 0.5ft thick of green siltstone. Green siltstone rock fragments occur throughout the beach.

13. The thin offshore Quaternary sands may limit the possibilities for moving well points seaward. The sands are fine to medium with permeabilities greater than 10 darcies. The Tertiary sediments have as much as 35% fines; that is, the grain size is less than 74 microns. The Tertiary sediments have permeabilities less than 10 millidarcies. That is, there is a three orders-of-magnitude difference in permeability between the Holocene sands and the Tertiary sediments.

14. At the beach, the thickness of Quaternary sands ranges from 4 to 12ft. In the offshore borings, the sands thicknesses ranged from 2 to 18ft. Offshore at roughly -35ft water depth, the sand thicknesses thin to zero. The offshore surface sands are thinner north of than south of Poplar Brook.

15. The Top of Tertiary map shows the top horizon of the impermeable and resistive Tertiary sediments.