CHEMICAL/ RADIOLOGICAL REMEDIATION AND WETLAND RESTORATION
Multi-Phase Remediation and Restoration Creates Pond, Wetlands and Walking Trails
ENTACT is performing an ecological restoration of 100+ acres, including creating a 14-acre open-water pond, 40 acres of wetland mitigation, 55 acres of upland enhancement, and close to two miles of public walking trails and boardwalks. We have completed the first two phases and are working on the third one.
The first phase was the remediation of impacted sediments from a 4.9-acre lake on the site. Lake sediments ranged from 0.5 to 7 feet and were underlain by a continuous layer of denser sands and clays.
Scope of work included:
- draining and dewatering of the lake,
- construction and operation of a temporary water treatment system,
- removal of 30,000 cubic yards of sediment,
- preparation of the on-site consolidation area,
- construction of a 4.4-acre 1-foot surface cover over the consolidation area,
- 3,600 cubic yards of imported cap fill,
- 3,600 cubic yards of topsoil and vegetation,
- wetland mitigation, seeding and planting within disturbed areas, wetlands, and upland areas; and
- installation of permanent stormwater features including conveyance channels and aprons in the encroachment area and a concrete headwall in the lake.
The second phase of the project addressed the remediation and restoration of 23 acres that were impacted by volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs), polychlorinated biphenyls (PCBs), pesticides, metals, and radiological waste, including Ra-226, Th-232, and U-238.
ENTACT managed the:
- assembly and operation of a water pre-treatment and storage system
- targeted excavation of visually observed non-aqueous phase liquids (NAPL) impacted soil and sediment
- installation of a barrier wall system consisting of steel sheet pile and connection to the existing steel sheet pile
- subgrade preparation including cutting/filling and material handling before installation of soil upland surface covers and a low permeability geosynthetic surface cap
- installation of the surface cover and the low permeability surface cap systems
- installation of NAPL recovery wells, barrier wall, and wetland piezometers, and amendment application wells
- waste and material management, and off-site transportation and disposal
- wetland restoration and mitigation
- installation of permanent stormwater measures
For the third phase of the project, ENTACT performed work in the western uplands, which included blending and capping of soil that exceeds radiological cleanup criteria; placement of cap fill material and topsoil within the forest land use area; base grading and consolidation of excess soils; and placement of cap fill material and topsoil.
For the wetland area, we removed fill materials, restored disturbed wetland surfaces with a wetland surface cover, invasive species management, re-seeded, and planted, and enhanced upland and riparian zone habitat.
The final phase of this project was the construction of paved and gravel access roads, paved parking and turn-around areas, and final surface coarse paving of existing road sections; construction of a trail network including stone and asphalt trails, public gathering areas, and bird blinds; completion of boardwalk and overlook platform; and site restoration.