River Mile 10.9 Removal Action Overview

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Nickolas Walsh
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1 River Mile 10.9 Removal Action Overview November 13, 2014 CAG Meeting Modified from CPG s RM10.9 Removal Action Final Design Report dated Nov

River Mile 10.9 Removal Action Activities Dredging: Approx. 2 feet of contaminated sediment were removed. Capping: A cap of approx. 2 feet was placed over the post dredge sediment.

2 River Mile 10.9 Removal Action Activities Dredging: Approx. 2 feet of contaminated sediment were removed. Capping: A cap of approx. 2 feet was placed over the post dredge sediment. The cap consisted of the following layers in ascending order: Active material/sand mixture was placed above the postdredge sediment (remaining contaminated sediment) to prevent contaminants from migrating to the surface of the cap. Geotextilewas placed over the active material/sand mixture. The geotextile is a fabric layer that keeps the active layer/sand mixture in place and prevents penetration by the armor stones. Armor stones, the sizes of which were determined by an engineer, were placed over the geotextile. Placement of the stones happened after the geotextile panels were placed. Sand (habitat layer) was placed over the armor stones to fill in voids to help reestablish the mudflat ecosystem. 2

3 August 7, 2013 to October 4, 2013: Dredging operations conducted Approximately 2 feet of contaminated sediments were removed. August 17, 2013 August 28,

to convey material from barge) is depositing the active material/sand mixture over the post

4 November to December 2013: Active Material/Sand Mixture Placement Approximately 10 inches of active material/sand mixture placed over post dredge sediment November 13, 2013 A telebelt(device to convey material from barge) is depositing the active material/sand mixture over the post dredge sediment. November 15, 2013 Photo shows an area where active material/sand mixture had been placed. 4

March 2014: Placement of geotextile and armor stone Geotextile:fabric layer used to keep the active layer/sand mixture in place and to prevent penetration.

Keeps the geotextile in place and also helps to protect the underlying cap from erosion due to high river flows and propeller wash from recreational

5 March 2014: Placement of geotextile and armor stone Geotextile:fabric layer used to keep the active layer/sand mixture in place and to prevent penetration. Armor stones: were placed after the geotextile panels were laid down. Keeps the geotextile in place and also helps to protect the underlying cap from erosion due to high river flows and propeller wash from recreational boating. March 15, 2014 Left Photo: geotextile panel being placed near the fire deptartmentboat launch Right Photo: armor stone placement overlying the newly placed down geotextile panel. CPG s contractor can be seen trimming the extra geotextile. 5

6 April 2014: Placement of geotextile and armor stone April 14, 2014: Photo of armor stones over recently-placed geotextile panel. Two different types of armor stone are seen in this photograph: Type B (the smaller of the two stones used) was used when the underlying substrate was hard pan. Type B armor stones were placed closer to shoreline where the flow rate is expected to be lower (less potential erosion). Type A (the larger of the two stones used) were determined by CPG s engineer to withstand a 100-year storm event. Photograph taken in area south of No Dredge Zone 6

April 2014: Placement of geotextile and armor stone continued April 23, 2014 North of the No Dredge Zone Mini excavator is in the background leveling out the armor stone north of the No Dredge Zone

When placing the geotextile panel: CPG s contractor laid the panels out flat to extend approx.

7 April 2014: Placement of geotextile and armor stone continued April 23, 2014 North of the No Dredge Zone Mini excavator is in the background leveling out the armor stone north of the No Dredge Zone South North No Dredge Zone Area South of the No Dredge Zone Type B stone can be seen here Exposed geotextile panel is shown here as it extends beyond the armor stones. When placing the geotextile panel: CPG s contractor laid the panels out flat to extend approx feet off the vegetated shoreline, anchoring it off the trees/brush until the armor stone could be installed. Process resulted in approx. 5 feet excess geotextile in places beyond where dredging/capping occurred CPG s contractors then trimmed back the geotextile to the edge of cap. Exposed geotextile is not a result of erosion 7

May 2014: Sand (habitat layer) placement began Sand layer was

8 May 2014: Sand (habitat layer) placement began Sand layer was applied over the armor stones to fill in voids to help reestablish the mudflat ecosystem. May 8, 2014: Initial test run of sand being applied via a telebelt over the armor stone. Area photographed is south of the No Dredge Zone. May 9, 2014: Photo of an area where one layer of sand was initially applied. 8

9 May 2014: Sand (habitat layer) placement continued May 9, 2014: Photo of sand layer 24 hours after initial test. Two layers of sand have been placed. May 12, 2014: Photo taken three days after the initial placement of two sand layers (on May 9 th ). 9

The row of exposed armor stone in the foreground is outside the dredge line and was not slated to be covered by sand.

10 May 2014: Sand (habitat layer) placement continued May 27, 2014: Background: The telebeltis conveying first layer of sand in an area just south of the fire department boat launch. Foreground: An area that was covered in the prior week. The row of exposed armor stone in the foreground is outside the dredge line and was not slated to be covered by sand. Helps to anchor the extra geotextile that extends beyond the area dredged/capped. CPG s contractor cut additional fabric once the row of armor stone anchoring the geotextile had been placed. 10

May 29, 2014: Photo taken from the southern most cap/dredge location and looking north.

11 May 29, 2014: Photo taken while standing south of No Dredge Zone looking north. The row of armor stone (acting as an anchor) can be seen on the right side of the photo. May 29, 2014: Photo taken from the southern most cap/dredge location and looking north. The final cap surface post installation can be seen here. May 29, 2014: CPG started to demobilize from RM

June 2014 -August 2014 Site visits with EPA, CPG and members of the boating community EPA and CPG discuss and plan for an effort to address high spots of armor stones.

12 June August 2014 Site visits with EPA, CPG and members of the boating community EPA and CPG discuss and plan for an effort to address high spots of armor stones. EPA and CPG engage in discussions regarding placement of buoy markers CPG and EPA identify areas of elevated armor stones and CPG takes coordinates of the locations September 2014 CPG begins effort on Sept. 29 th to move high spots of armor stones Photo credit: Harvey Morginstin. Photograph titled Lyndhurst LT June jpg and was provided to EPA on 6/24/2014 via . EPA oversees this effort 12

A red buoy marker not placed by CPG and EPA is seen. Also, a rower passing by.

13 September 29, 2014: CPG effort to move high spots of armor stones Conditions prior to start of work. Row of armor stones anchoring geotextile seen in foreground. A red buoy marker not placed by CPG and EPA is seen. Also, a rower passing by. CPG s contractor removes high spots of armor stones in areas closer to the channel. Area is south of No Dredge Zone. 13

Based on observations that day, it was estimated that approximately 3-4 inches of sediment

14 September 30, 2014: CPG effort to move armor stones CPG s contractor continues to manually remove high spots of armor stones. Based on observations that day, it was estimated that approximately 3-4 inches of sediment had accumulated above the sand layer. River level at low tide was higher than anticipated. As such, work was scheduled to resume the following week. 14

October 6, 2014: Last day of effort CPG s

CPG s contractor manually removes armor stones

15 October 6, 2014: Last day of effort CPG s contractor utilized a tracked vehicle in effort to remove armor stones in area north of No Dredge Zone. CPG s contractor manually removes armor stones near channel in area north of the No Dredge Zone. Area near fire department boat launch 15

Row of armor stones anchoring geotextile is in foreground.

16 RM10.9 site visits after CPG s efforts to remove high spots of armor stones October 8, 2014: Area south of No Dredge Zone. November 4, 2014: Area north of No Dredge Zone. Row of armor stones anchoring geotextile is in foreground. These stones are outside the dredged/capped area, line almost the entire length of the mudflat, and will remain as they help to anchor the underlying geotextile layer. 16

Phase 1 Habitat Replacement & Reconstruction

Phase 1 Habitat Replacement & Reconstruction Marc Greenberg, USEPA greenberg.marc@epa.gov Hudson River EPA s Expectation of Habitat Reconstruction & Replacement provides diverse habitats Plants, plankton,