Soil Vapor Extraction at the Sacramento Army Depot Superfund Site, Tank 2, Operable Unit 3, Sacramento, California

Site Name:

Sacramento Army Depot Superfund Site


Sacramento, California

Period of

August 1992 to January 1993


Full-scale cleanup


James Perkins
Terra Vac, Inc.
14798 Wicks Boulevard
San Leandro, CA 94577
(510) 351-8900

Soil Vapor Extraction - 8 vacuum extraction wells, positive displacement blower, vapor-liquid separator, and primary and secondary carbon filters - Wells installed to depths of 15 to 28 feet below ground surface

Cleanup Authority:
CERCLA and Other: Federal Facilities Agreement - ROD Date: 12/9/91

SIC Code:
3471 (Electroplating, Plating,
Polishing, Anodizing, and Coloring)
3479 (Coating, Engraving,
and Allied Services, Not Elsewhere Classified)
Point of Contact:
Dan Obern
Sacramento Army Depot
8350 Fruitridge Road
Sacramento, CA 95813-5052
(916) 388-2489

Chlorinated and Non-Chlorinated Aliphatics - 2-Butanone (0.011 to 150 mg/kg); Ethylbenzene (0.006 to 2,100 mg/kg), Tetrachloroethene (0.006 to 390 mg/kg), and Xylenes (0.005 to 11,000 mg/kg)

Waste Source:
Underground Storage Tank

Type/Quantity of Media Treated:
Soil - 650 yd3 (25 ft by 35 ft by 20 ft deep) - Silt with clay content of <30%; moisture content - 25.6 to 26.5%; air permeability 1.7 x 10[Sup -7] to 6.2 x 10[Sup -5] cm/sec; porosity - 44.3 to 45.8%; TOC 0.011 to 0.44%

Purpose/Significance of Application:
This application of SVE was in a relatively small volume of low permeability, heterogenous, contaminated soil.

Regulatory Requirements/Cleanup Goals:
- 1991 ROD specified soil cleanup levels for the Tank 2 Operable Unit of 2-Butanone (1.2 ppm); ethylbenzene (6 ppm); tetrachloroethene (0.2 ppm); and total xylenes (23 ppm) - Cleanup levels were to be achieved within 6 months of system operation

- The specified cleanup levels were achieved within six months of system operation - Levels of 2-butanone, ethylbenzene, tetrachloroethene, and total xylenes were reduced to below detection limits

Cost Factors:
Total cost of $556,000 - costs directly associated with treatment (including mobilization/setup, startup, operation, sampling and analysis, demobilization) - $290,000 of total cost attributed to treatment of non-Freon contaminants (adjusted assuming operation costs equivalent for Freon and non-Freon contaminants)

The Sacramento Army Depot (SAAD) located in Sacramento, California is an Army support facility. Past and present operations conducted at the site include equipment maintenance and repair, metal plating, parts manufacturing, and painting. During investigations of the facility in 1981, soil contamination was identified in the area of an underground storage tank and designated as Tank 2 Operable Unit. Tank 2 had been used to store solvents and the primary contaminants of concern included ethylbenzene, 2-butanone, tetrachloroethene, and xylenes. These constituents were detected in the soil at levels up to 11,000 mg/kg. A Record of Decision (ROD), signed in December 1991, specified soil cleanup levels for the four primary constituents of concern and specified a six month timeframe for achieving these levels. SVE was selected for remediating the contaminated soil because it was determined to be the most cost effective alternative.

The SVE system consisted of 8 vacuum extraction wells, a vapor-liquid separator, and primary and secondary carbon adsorption units, and was operated from August 6, 1992 to January 25, 1993. The system achieved the specified soil cleanup levels a month ahead of the specified timeframe. In addition, the SVE system removed approximately 2,300 pounds of VOCs. During system operation, Freon 113 was unexpectedly encountered. Extraction of Freon 113 significantly increased the quantity of carbon required to treat the extracted vapors.

The total treatment cost for this application was $556,000. This cost was greater than originally estimated primarily as a result of the additional carbon required as a result of the presence of Freon 113. A computer model treatability study was used for this application. The study predicted SVE using 4 extraction wells could reduce concentrations of volatile organics to non-detectable levels within 6 months.