ENTACT completed the multi-phase remediation of a 100-acre industrial site located on a river in preparation for mixed-use redevelopment. The initial phase was completed over 3.5 years and consisted of 34 acres located in the central portion of the site. Scope of work included: excavation of approximately 932,000 cubic yards of chromium ore process residue (COPR) and chromium impacted material in an incremental manner to control dust and water generation, and to accommodate direct loadout of material; loading of over 53,000 truckloads of excavated material classified as hazardous for transport and disposal off-site; design, installation, and operation of a vacuum well point and deep well groundwater extraction system to lower the groundwater elevation and water content of waste materials as much as practicable; installation and abandonment of observation wells, inclinometers and piezometers; protection and abandonment of several existing monitoring wells; import, placement and compaction of approximately 880,000 cubic yards of backfill to bring the site up to the final surface grades.
ENTACT was engaged to complete the second phase of remediation, completed over three years and located north and south of the previously remediated area. Scope of work included: demolition of select above grade and subsurface structures; utility disconnects within city streets; design, installation and operation of a vacuum well point and deep well groundwater extraction system; assembly and operation of a construction water treatment system; placement of over 400,000 cubic yards of surcharge materials in a rolling fashion over the north and south areas for subgrade consolidation; installation of over 180,000 square feet of epoxy coated sheet pile with grouted or sealed interlocks on perimeters of the north and south areas; shoring adjacent to main roads, including both sheet pile and soldier pile systems; excavation of 250,000 cubic yards of overburden and chromium impacted soil to a maximum depth of 20 feet bgs; segregation, on-site management and off-site disposal of excavated material; import, placement and compaction of 285,000 cubic yards of backfill to bring excavated areas to subgrade elevations; construction of two 10-acre capping systems consisting of geosynthetic and cover soil components; and installation of a gas venting and groundwater extraction system within capped areas.