Dredging of Mercer County Miry Run (Dam 21 Lake)

Mercer County is currently conducting maintenance dredging for a portion of the impoundment (Miry Run) behind Dam 21. The focus of the dredging is to remove sediment in the vicinity of the water trail proposed as set forth in the January 2020 Master Plan for the Miry Run Ponds Park. Initially it was assumed, and was later confirmed, the material to be dredged was clean (i.e. below NJDEP residential reuse threshold) and that the dredged material would be placed on the adjacent farm fields and disked into the soil. The project was based on the Dredging Concept Plan that initially identified the areas proposed for dredging and thin layer application. If the dredged sediments from the project had been determined to be above NJDEP’s threshold for the intended use in the placement areas, it would have been dewatered onsite and disposed of at a regulated facility.

Based on an evaluation of the completed bathymetric survey, which was completed as part of the Master Plan, and the location of the water trail, Princeton Hydro identified three primary areas where the maintenance dredging will be focused.

Dredging Area 1 is in the main body of the lake just downstream of Line Road and would generate approximately 34,000 cubic yards of dredged material.

Dredging Area 2 is in the northeast cove, just north of Dredging Area 1. Dredging Area 2 has approximately 4,900 cubic yards of accumulated sediment.

Dredging Area 3, the northwestern cove, would require the removal of approximately 7,300 cubic yards of accumulated sediment. Total anticipated dredging volume is roughly 46,200 cubic yards.

The final project scope included (1) a sediment sampling plan, (2) sample collection and laboratory analysis, (3) engineering plan preparation, (4) preparation and submission of all NJDEP regulatory permitting materials, (5) preparation of the technical specification, (6) bid administration, and (7) construction administration and observation services.

Click here to learn more about this project, see additional photos, and watch drone footage.