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Sub-Slab Depressurization System Installation

Project Profile

  • Project Location : New York
  • Owner Industry : Contractor/Consultant
  • Gwtt Scope : Design, Build, Site Civil Work
  • Contract Value : $12M
  • Project Duration : 6 Months
  • Contaminants : Chlorinated Solvents

Key Project Details

  • Furnished and installed all treatment equipment including knock out tank, four 150-hp Kaeser blowers, heat exchanger, 150-ton chiller and carbon units.
  • Installed 4-inch to 20-inch diameter schedule 10 hot dipped galvanized piping network. Main header installed below ground from treatment system to active facility—route to roof, span across to secondary headers and tie into building points. All above grade piping is heat traced and insulated.
  • Provided and installed two 10,000-lb vapor phase granular activated carbon units to treat captured vapors.
  • After successful completion of the project work and system startup, GWTT’s O&M team took over operation and maintenance of the treatment system.

PROJECT CHALLENGES

  • Work was performed on an active client facility which required ongoing coordination to make sure disruptions to operations were avoided.
  • Multiple project subcontractors worked simultaneously in a small project footprint, requiring dedicated PMO focus.

Project Narrative

GWTT installed a sub-slab depressurization system in and actively operating 1-million-square-foot facility that was plagued with sub-slab soil vapor containing chlorinated solvents (PCE & TCE) for mitigation. We furnished and installed all treatment equipment. The piping network included 4-inch to 20-inch diameter schedule 10 hot dipped galvanized piping. The main header was installed below-ground from the treatment system (route to roof, spanned across to secondary headers and tied into building points). All above grade piping was heat traced and insulated. Treatment equipment included: two 10,000-lb vapor phase granular activated carbon units to treat captured along dual contained condensate storage. GWTT modified the existing active facility’s structural and architectural features to serve as the treatment facility, including roof curbs, secondary containment, access ramps, generator, electric and blower rooms, roofing, HVAC, electrical systems, and fire suppression and alarming.

Additionally, GWTT provided and installed a 2400V electrical sub-station to control system power, including 250-kilowatt standby generator.  We also provided and installed all power and control circuits throughout the treatment facility and to remote system extraction points. The project included installation of a Supervisory Control and Data Acquisition (SCADA) in treatment system control room for fully automated operation of the system.

After successful completion of the project, GWTT’s O&M team took over operation and maintenance of the treatment system.