The Knolls Laboratory L4 Pumphouse Sinkhole Repair Project is being undertaken to repair an existing concrete retaining wall along the edge of the Mohawk River where the river water flow is eroding the retaining wall and the surrounding shale rock face.
Office of NEPA Policy and Compliance
August 26, 2026
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The Knolls Laboratory L4 Pumphouse Sinkhole Repair Project is being undertaken to repair an existing concrete retaining wall along the edge of the Mohawk River where the river water flow is eroding the retaining wall and the surrounding shale rock face. The wall will be repaired by installing a turbidity curtain in the river around the work area; removing loose fill material from behind the retaining wall; drilling and doweling rebar into the sound bedrock; and installing form-work and one-sided bracing to allow for the placement of concrete into the void and restoration of the affected area.