Fort Wayne, IN: Large Diameter Auger Steam Stripping and ZVI Mixing

Fort Wayne, IN: Large Diameter Auger Steam Stripping and ZVI Mixing

Project Description

services-steam-enhanced-soil-mixingSignificant Project Features:

  •  Steam stripping with 9-foot diameter auger to depths of 16 feet below ground followed by soil mixing with zero-valent iron, both to treat TCE contamination in the site soils.
  • Excavation, transport to the landfill, and backfilling of 17,000 tons
  • Allu Rotary Tool In-Situ Stabilization to lock up tar with grout and site soils.

 Project Background:

GSI was hired as the general contractor to perform the remediation of their Former Magnavox Area project in Fort Wayne, Indiana.  The project included removal of approximately 17,000 tons of contaminated (non-hazardous) soils to the local landfill at depths from 8 to 18 feet below ground surface.  A portion of those soils (2,300 CY) was contaminated with TCE above allowable levels for disposal at the local landfill.  Those soils required steam stripping using a 9 foot diameter soil mixing auger attached to a Delmag RH-18 hydraulic drill.  A boiler was used to provide high-pressure steam which was injected with the auger to heat the soils and vaporize the TCE.  A vapor shroud and vacuum treatment system was used to capture the TCE in granular activated carbon canisters.  Following steam stripping of the majority of the TCE, Zero-Valent Iron (ZVI) was injected with bentonite slurry to reduce the final TCE below disposal requirements.

Description of Work

  • Site preparation including erosion controls, stabilized construction entrance, decon pad, fence removal and new fence installation and site improvements.
  • Removal of concrete foundations, footings, and slabs.
  • Clearing and grubbing.
  • Removal and stockpiling of a 5,400 cubic yards of soil on the southern slope of the site to both allow for soil excavation in that area and to provide approximately ½ of the clean soils to backfill the excavations.
  • Treatment of 2,300 CY of TCE contaminated soils to a maximum depth of 16 feet bgs.
    • Setup off gas treatment plant
    • Steam-stripping with large diameter auger
    • Analysis of off-gas TCE levels throughout the steam stripping
    • Soil Mixing with zero-valent iron delivered with bentonite slurry
    • Spoils management
    • Sampling and testing
  • Excavation and transportation of 17,000 tons of contaminated (non-haz) soils to the local landfill.
  • Backfilling of all excavations with off-site and/or on-site borrow.
  • Waste and contact water management
  • Cleaning of existing storm sewer system after installation of 4 new catch basins
  • Site restoration including grading, seeding, and sprinkler system repair
  • The work was completed over a seven month period.

Key Project Objectives and Challenges

  • GSI was the general contractor and self-performed the majority of the project with our own personnel.
  • Steam stripping and ZVI mixing of TCE contaminated soils to below hazardous levels.
  • Safe excavation and backfilling of excavations up to 18 feet below ground.
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