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Environmental and Geotechnical Construction Services


Former MGP Site ISS - Northeast

  • Multi-year MGP site remediation for this major northeast utility
  • Transportation and disposal of 52,000 tons of MGP impacted soils
  • In-situ solidification/stabilization of 169,000 CY of impacted material
  • Installation of soil-crete retaining wall
  • Utility relocations, protection and abandonment
  • Temporary Containment Structure

A large Manufactured Gas Plant operated on this 8-acre site from the early 1900’s to the mid 1950’s. This plant used coal and petroleum products to create a flammable gas which was piped to the surrounding communities, where it was used for lighting, heating and cooking. The gas manufacturing process generated an oily liquid waste known as “coal tar” which has affected the subsurface soils and the groundwater.

ENTACT was engaged to perform a multi-year MGP site remediation for this major northeast utility. Site constraints included gas holders, concrete footings, foundations and subsurface utilities that required abandonment and removal prior to ISS, as well as overhead power lines which required minimum OSHA clearance and line shielding. Scope of work included excavation, transportation and disposal of 52,000 tons of MGP impacted soils; in-situ solidification/stabilization of approximately 168,000 cubic yards of impacted material using cement-bentonite-slag grout to a maximum of 30 feet deep using 8-foot diameter vertical augers; management, transportation and disposal of 15,750 tons of DSM derived spoils; excavation, stockpiling, and re-use of 30,000 tons of lesser impacted on-site material; installation of a soil-crete retaining wall; construction, demolition, and reconstruction of a parking facility; utility removal, relocation and replacement; and site restoration. Excavation and spoils management activities were performed under a temporary containment building equipped with a vapor management system.