PROJECT OF THE MONTH—JANUARY 2006
Client:
U.S. Air Force Space Command and
Air Force Center for Environmental Excellence

Project Cost:
$1 million

Project Duration:
2003–2008

Parsons’ Services:

  • Interim action remediation work plan
  • Remedial design
  • Remedial construction
  • Performance-based cleanup
  • Long-term monitoring
  • Remedial technologies
  • Operations and maintenance
Groundwater monitoring wells dot the landscape at Buckley Air Force Base
Main gate
East of Denver, in Aurora, Colorado, is Buckley Air Force Base (AFB), home of the U.S. Air Force Space Command’s 460th Space Wing and 38 other units representing each branch of service. Buckley boasts the only military runway in Colorado capable of handling weapons-loaded aircraft and can support every type of cargo and fighter aircraft from every service and command. Strategically, Buckley AFB provides superior global surveillance, worldwide missile warning, homeland defense, and expeditionary forces.

Parsons has supported Buckley since 2001, performing such tasks as the remedial investigation of former sludge-drying areas, well-head assessment for onbase water wells, vulnerability assessment of the water distribution system, preparation of a draft military housing master plan, and the development of a water supply contingency plan.

To dewater contaminated soil, more than 50,000 yd were excavated to an average depth of over 32 ft.
A 1,400-ft, air-sparging trench is being dug to mitigate offsite migration of dissolved contaminants.
To dewater contaminated soil, more than 50,000 yd were excavated to an average depth of over 32 ft.
A 1,400-ft, air-sparging trench is being dug to mitigate offsite migration of dissolved contaminants.

In 2003, Parsons was contracted to complete an interim remedial action that would remove the source of tetrachloroethene (PCE) contamination in the soil and shallow groundwater at Site 10, a former warehouse area in the northern sector of the base. The remedial action plan was prepared to support the Air Force’s decision document, which received concurrence from the U.S. Environmental Protection Agency and the Colorado Department of Public Health and Environment.
Cut-away of the air sparging treatment system

Cutaway of air-sparging treatment system.

After the Air Force signed the Interim Action Record of Decision, Parsons began the project’s construction phase to reduce the source area’s PCE groundwater concentrations from 30 mg/liter to less than 1 mg/liter. To succeed in the long-term goal of reducing the concentrations to below 0.1 mg/liter, Parsons selected an approach that included excavating and dewatering the 1-acre source area. More than 50,000 yd of soil were excavated to an average depth greater than 32 ft. Samples collected from the soil stockpiles characterized the excavated material. Onsite screening methods identified the soil removed from the hot spot, which was separated and transported for disposal at a RCRA-permitted landfill. Based on the analytical data, other stockpiles were used for clean backfill. No hazardous waste was generated, and groundwater entering the excavation was removed and treated to eliminate 99% of the PCE before discharge.

Parsons will operate a base boundary treatment system, including a 1,400-ft, air-sparging trench to mitigate the offsite migration of dissolved contaminants. The trench, located inside the base boundary, will remove the lower PCE concentrations by intercepting the shallow aquifer before it leaves the base. Performance-monitoring wells will be installed within the source area excavation and along the remediation trench, and Parsons will conduct semiannual groundwater monitoring for the next 3 years to demonstrate compliance with the site’s remediation goals.

Safety--Make it Personal!

Site manager Tom Dragoo (left), project manager Doug Downey (not shown), and safety managers Tim Mustard, Judy Blakemore, and Jim Owen are proud of the project’s commendable safety record of zero recordable incidents for over 2,000 hours of heavy equipment operation.

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