Wilder Projects

Standard Steel & Metals Salvage Yard
Superfund Site

Click Here for Adobe PDF version of this page.

Project Location: Anchorage, Alaska

Client: Alta Geosciences, Inc.

Construction Cost: $4.8 million

Wilder’s Role: Prime

Construction Period: 3/98 - 10/98

Project Highlights

  58 Acres Site Remediation
  UXO Handling and disposal
  Chemical treatment of contaminated soil
  Confined disposal facility construction
  Installation of groundwater well vaults
  Installation of double-containment piping
  Clearing, grubbing and grading
  In situ treatment of contaminated soils
  Shoreline protection
  Water treatment system construction
  Water treatment system operation
  Dewatering/groundwater treatment & discharge
  Cement stabilization of contaminated soil
  Underwater excavation

Excavation and stabilization was performed for all on-site contaminated soils. An on-site containment cell was constructed for the stabilized material. Included in the excavation was removal of soils below the water table in a smear zone area contaminated with PCBs. The new containment cell was constructed above the water table with the contamination level of the materials dictating their location in the cell. The cell was covered with a drainage geonet, liner and insulation. Final cover was several feet of select gravel. Drainage structures were placed at the site, and the cell was protected from the adjacent Ship Creek by a massive rip-rap erosion control structure designed for 1000 year flood event.

The site was excavated in 40’ square by 6” deep layers that allowed confirmation testing. The area was dewatered and the water was pumped to a 70,000-gallon holding tank prior to being treated and discharged.

Lead-contaminated material was treated with the patented MAECTITE^® process that utilizes a reagent that combines with the lead present in the soil to chemically bind the lead into a new, stable form. 6,000 CY of lead-contaminated soil were stabilized using the MAECTITE^® process.

PCB-contaminated material was stabilized through solidification/encapsulation in a mix with portland cement and fly ash.

Early in the execution of the work, Wilder discovered large quantities of unexploded ordnance (UXO) debris. UXO operations required extensive planning, modifications to operations, protective systems for workers and equipment, and effective coordination with owners, engineers, explosive ordnance disposal teams from Elmendorf Air Force Base, and the Anchorage Police.

PCB-contaminated water was removed from the smear zone area, pumped into a holding tank, then processed through a treatment system consisting of a flocculation tank, filters and final scrubbers of granulated activated carbon (GAC). Over 500,000 gallons of water were treated and discharged.

Wilder excavated and constructed a massive rip-rap erosion control structure (14,000 tons) to protect the consolidation cell from Ship Creek. Sheet pile was driven to keep the creek bed in place during excavation. Three acres of geonet, liner, and insulation, covered with three feet of imported gravel was installed.