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J 6 1996 1 15 ki fE TECf?Pl f ! 'E No 2616 P 1/3j - 95-WP 103 05 INTRODUCTION The Unterdruck-Verdampfer-Brunnen(WB)technology(roughly translated to Vacuum Vaporizer Well) is an un-situ system for gmundwater remediation, particularly for aquifers wntarnin with volatile organic compounds (VOC) The UVB system was developed and patented by TEG mbK Reutlingen, Germany, and is now being demonstrated and used in the United States In conjunction with the technology developer (EEG Technologies Corporation), Roy F Weston, Inc (WESTON) has completed an 18-month demonstration program of the UVB system at March Aar Force Base(AFB), Riverside, California under subcontract to Blank& Veatch Waste Science, Inc The system has been demonstrated for March AFB, the U S Environmental Protection Agency, Office of Research and Development (USEPA ORD) under the S.uperfund Innovative Tecnology Evaluation (SITE) Program, and the U S Army Corps of Engineers, Omaha District who is administering the innovative technology program for March AFB Tc.s is the first application of the UVB system at a federal facility STUDY OBJECTIVES March AFB is committed to the testing of innovative technologies for remediation of contaminants found on the base The primary objective of the study was to evaluate the feasibility of the UVB system, for removal of chlorinated hydrocarbons (primanly trichloroethene (TCE)) from the groundwater, and to evaluate cost effectiveness of the treatment. SITE DESCRIPTION March AFB is located east of the City of Riverside,Riverside County, California, approxsmately 60 miles east of Los Angeles The study was conducted at Site 31 (Unc,onfnmed Solvent Disposal), Operable Unit l (Figure 1) Site 31 is underlain by fine-grained sediment dominated by fine-grained sand and silt As is typical of alluvial and fluvial deposits, individual lithologw units tend not to be laterally continuous. Based on lithologic logs available from this and previous site studies, the followmg generalized alluvial sequence underlies Site 31 fine sandy silt to clayey silt and silty fine sand to depths of about 40-50 feet below ground surface(bgs), relatively continuous interval of clean sand (Le., containing few fines) to about 50- 60 feet bgs, interbedded silt, sand and minor clay extending to weathered granitic basement rock. The first occurrence of saturated soil is reported in most boring logs between approxunately 45-55 feet bgs Dry to slightly moist conditions were reported between approximately 100-120 feet bgs in 31MWI This fine-grained interval is considered a bamer to the vertical flow of groundwater in this location and, at least locally, appears to separate the alluvial aquifer into two zones. This interpretation is further supported by a groundwater elevation head differeatial between 31MW1 and adjacent 4MW'14 of approximately 4 5 feet. The depth to weathered granitic basement rock is irregular, ranging from approximately 30-160 feet bgs across the site The hydrogeologic conditions at Site 31 are fairly complex and hydraulic parameters appear to vary widely in both vertical and horizontal directions Depth to groundwater in developed wells is approximately 40 feet bgs Groundwater flow direction across the site is predominately toward the south at an average gradient of approximately 0 007 feet/faot. Based on aquifer test results conducted on 2