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' Problem Assessment Report Page 12 Ranch Market,23559 South Santa Fe Road,Riverbank,CA November 8,2000 7.2.4 Soil Vapor Analytical Results The field influent TPHg concentrations measured while extracting vapor from V-1, V-2, and ' V-5 were at the maximum detection limit of the FID, 10,000 ppmv (Table 6) Laboratory analyses of samples collected during the SVE test and the SVE/AS test, are summarized in Table 7 The laboratory analytical results and chain-of-custody records for air samples are ' included in Appendix D Based on the soil vapor sample analytical data, TPHg concentrations were reported between ' 1,500 ppmv TPHg in sample Inf-AS-1, taken at the influent sample port to the thermal oxidizer and 8,200 ppmv TPHg in sample VE-V-2, taken at well V-2 during Test#1 The ' laboratory reported 3,200 ppmv TPHg in Inf-SVE-2, also taken at the thermal oxidizer Influent sample port, approximately five minutes before beginning the air sparge test The same sample location was reported to have a concentration of 1,500 ppmv TPHg ' approximately 5 hours after the start of the air sparge test The influent samples were collected while infecting air into AS-I at 6 scfm and between 7 and 8 psi and extracting from all six vapor extraction wells The final sample collected five minutes before termination of ' the air sparge test contained 2,800 ppmv TPHg 7.2.5 SVE Mass Removal Rates ' The total mass of TPHg and benzene removed during the test were calculated using the influent air sample analytical results The calculated TPHg and benzene mass removed during the SVE and air sparge tests was approximately 102 pounds and 19 pounds, respectively(Table 8) Assuming an average extraction rate of 250 scfm and an average TPHg concentration of 1,000 ppmv, the daily extraction rate would be 100 pounds of TPHg and 16 pounds of benzene from the six extraction wells ' 7.3 Vapor Extraction and Air Sparge Radius of Influence t Refernng to SVE Test#2 results present Table 6, an applied vacuum to well V-1 resulted in 0 20 to 0 32 in H2O of induced vacuum in well V-3 located 38 feet away Referring to SVE Test#3 results present Table 6, an applied vacuum to well V-5 resulted in 0 26 to 0 43 in ' H2O induced vacuum in well V-3 located 36 feet away An increase in applied vacuum resulted in an increase in the induced vacuum Based on the induced vacuum responses and the slight rise in groundwater levels observed during the tests the estimated soil vapor ' extraction radius of influence is approximately 40 feet The estimated radius of influence assumes an induced vacuum of 0 2 in H2O will be present at 40 feet away from the extraction well Refernn to the SVEIAS test results resent Table 5, airsparging resulted in an increase in g P the dissolved oxygen concentrations in well MW-1 and well V-1, located 7 and 21 feet from ' AS-1 respectively Referring to the SVE/AS Test#5 results present Table 6, air sparging resulted in positive pressure readings in wells MW-1, MW-2, and MW-4 that are located 7 ' feet, 34 feet, and 35 feet away from AS-1 respectively Although the air sparging did not result in an immediate increase in TPHg vapor concentration, the increase in dissolved • oxygen concentration and slight rise in the water table in offsetting wells indicates a radius of ' influence of approximately 30 feet File PAR-report doe SECOR International Incorporated