Portland, Oregon
The former 570-acre Pompton Lakes Works (PLW) facility commenced operations in the early 1900s. Following the cessation of site activities in 1994, the PLW was gradually dismantled and closed. E.I. du Pont de Nemours and Company was subsequently mandated by the NJDEP to execute a remedial investigation at the site to determine the type and scope of contamination. The COCs included mercury in the sediment, and copper, lead, and zinc in the upland soil.
Sevenson’s scope of work included the removal of upland marsh soil; excavation of shallow water sediments; mechanical and hydraulic dredging of 134,000 CY of mercury-contaminated sediment; dewatering using desanding through a Total Clean system and six 600 CF filter presses; T&D of all waste; and hydraulic placement of a sand layer. A last-minute directive from NJDEP required the construction, operation, and maintenance of a 2,500-GPM wastewater treatment system, which treated and discharged >116M gallons of mercury-impacted water. Due to the small size of the layout area for the filter presses, WWTP, and material management/loading operations, Sevenson efficiently designed the filter press and WWTP area to squeeze into the footprint of the 1.1-acre staging area.