Amid a residential suburban area, harmful contamination was found in the sandy soils of a 15-acre site where factories such as Imperial Oil and Champion Chemical had operated since 1917. Contamination included volatile organic compounds, PCBs, polycyclic aromatic hydrocarbons, petroleum hydrocarbons, phthalates from plastics, metals, lead and arsenic. The surrounding wetlands and residences were at risk from these harmful contaminants, so the area was designated a Superfund site and the United States Army Corps of Engineers enlisted Conti to clean it up.

Conti Federal performed large-scale soil excavation and groundwater remediation including hydraulic containment of the site and large scale load out and disposal of 180,000 cubic yards of excavated material. The team implemented unique separation techniques to avoid cross contamination, including in-situ sampling for waste characterization of hazardous and nonhazardous soils for offsite treatment and disposal. The team also designed, procured and installed a 300 gallon-per-minute water treatment plant onsite.

A major feature of the project was the construction of a complex soil-bentonite hydraulic barrier structural slurry wall with up to 74-foot depths around the site perimeter. Conti Federal performed value engineering to redesign the alignment of the wall to lessen impact to excavation and dewatering limits, as well as to avoid nearby high voltage power lines and local residences.

Along with the slurry wall, which saved the client over $2 million, Conti Federal provided innovative ideas such as excavation and load out methodologies increasing efficiency and saving time and costs.

Key features of the project included:

  • Constructed structural slurry wall (2,600 linear feet)
  • Installed sheeting (25-foot panels) in slurry trenches
  • Excavated soil (290,000 tons)
  • Backfilled and graded
  • Constructed temporary water plant
  • Sampled wastes onsite
  • Transported and disposed of wastes
  • Restoration of site and wetlands

Awarded Project of the Year for the New York region in the Industrial/Manufacturing category by Engineering News-Record.