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Environmental Assessment Report 4 San Joaquin Catholic Cemetery,Cemetery Lane and Harding Way Stockton,CA June 29, 19% extracted from two wells(VW-3 and VW-20) at three flow rates during three one-hour penods from each well and from the four other vapor extraction wells(VW-2S,VW-4,VW-1 S, and VW-1 D) for shorter penods (approximately 20 minutes) Wells VW-3 and VW-21)were tested at three different flow/vacuum levels to determine optimum flow rates for system design Extracted vapors removed by the vacuum pump were routed through an internal combustion unit(VR Systems model V3C) approved for treatment by the San Joaquin Valley Unified Air Pollubon Control District Induced vacuum readings at the surrounding monitoring wells and VEWs, and applied vacuum, LEL, oxygen, and flow rate readings at the extraction point were collected during the test at 10 to 15 minute intervals Extracted vapor samples from each extraction point were collected in Tedlar bags when steady state pneumatic conditions had been attained at selected flow rates The extracted soil vapor samples were labeled, stored in an insulated container at ambient temperature, and submitted under a chain-of-custody manifest to a State-certified laboratory for analysis of BTEX and TPH-G In addition, one extracted vapor sample was analyzed for methane 42 Soil Vapor Extraction Test Results Measurements collected during the soil vapor extraction test on May 9, 1995 are summarized in Table 3 Flow rates obtained during testing ranged from 3 to 38 cfm at vacuums ranging from 34 to 106 inches of water During the tests on VW-3 and VW-2D, maximum mechanically achievable vacuum/flow could not be reached due to the high concentrations of hydrocarbons in the extracted vapors and the limitation of mass loading on the internal combustion and Radius of influence was calculated for wells VW-3,VW-2D and VW-2S Radius of influence was calculated by extrapolating the regression line calculated for log vacuum versus distance down to 0 1 inches of vacuum Graphs 1,2 and 3 are graphs of log vacuum versus distance for wells VW-3, VW-213 and VW-2S, respectively Radii of influence were 59, 32 and 75 feet for VW-3,VW-21D and VW-2S, respectively TPH-G concentrations in extracted vapor samples from VW-3 were 43,000 mg/m'after 27 minutes of continuous extraction, and 45,000 mg/m' after 125 minutes of continuous extraction Vapor samples collected from VW-2D had concentrations ranging from 46,000 mg/m'after 15 minutes of continuous extraction, and 21,000 mg/m'after 115 minutes of continuous extraction Methane concentrations were below method detection limits in the VW-38 The analytical results indicate a decline in TPH-G concentration in vapors pulled from VW-2 in the deep zone, and practically unchanged hydrocarbon vapor concentration in vapors extracted from the shallow zone by VW-3 Based on the concentration observed in vapor samples and achievable flow rates observed during testing on VW-3 and VW-2D, mass extraction rates would initially be as high as 70 pounds per day from the shallow zone near VW-3 and 30 pounds per day from the deep zone near VW-2D • SJCCEAR rpt(Mist 171 ❑�� GROUNDWATER ❑❑ TECHNOLACY