about
services
Technical
contact
projects
home

 

    

McClelland AFB
Sacramento, CA

 


Client:

Base Conversion Agency,
Sacramento, CA

Equipment Near the Site PRL T-44,
Operable Unit (OU) G

    

The SESR demonstration was conducted from November 1999 through June 2000 at Site PRL T-44, Operable Unit (OU) G, located in the northeastern/east central portion of the base. PRL T-44 was the location for an aircraft washrack, aircraft maintenance facility, and an underground storage tank area. Potential wastes that may have been released at this location due to operational activities include solvents, petroleum products, priority pollutants, and volatile organic compounds (VOCs); however, existing site knowledge indicates that the primary contaminant of concern (COC) is trichloroethene (TCE), a chlorinated solvent. The primary objective of the SESR demonstration was to assess the performance of SESR (i.e., percent DNAPL/contaminant removal) and cost of implementation (i.e., source/”hot-spot” treatment) as compared to conventional groundwater remediation techniques, such as dual phase extraction and pump and treat, currently in use at McClellan AFB.

 

 TASKS

 
  • Pre-tracer tests to confirm hydraulic capture, and to estimate the quantity of NAPL present within the test cell areas. Eight tracer tests were conducted due to the complex geology encountered within the demonstration plot.
  • Due to the very complex and apparently non continuous nature of the geologic strata beneath the site at a depth of 110 to 112 feet, the final demonstration plot consisted of two test cells that measured approximately 4 feet by 6 feet (Test Cell #1) and 5 feet by 7 feet (Test Cell #2).
  • SESR did increase the solubility of the TCE within test cell #1, resulting in enhanced contaminant/mass removal. During the surfactant/freshwater injection, the TCE concentration in extraction well EW-356 (test cell #1) ranged from an initial low of 1.57 mg/l to a high of 25.30 mg/l. The TCE concentrations were low to non detect in extraction well EW-355 (test cell #2) during the surfactant injection.
  • TCE mass was removed during the surfactant flood. A total of 0.11 liters, or 169 grams, of TCE was removed from extraction well EW-356 (test cell #1) during the surfactant injection phase of the demonstration. Enhanced TCE removal was not measurable in test cell #2 (i.e., extraction well EW-355) due to limited TCE present at the site.
  • The complexity of the subsurface at the demonstration site at McClellan AFB had a major impact not only on the technology implementation, but also on the quantifiable success of the technology. Specifically, the sand lenses in the saturated zone at PRL T-44 were found to be discontinuous, which limited recovery of injected fluids. Hence, the final test cell size was significantly decreased to assure complete recovery of all injected fluids.