ARCHIVED REPORTS XR0002753 - Laserfiche WebLink

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Atlantic Richfield Company 3 ARCO Service Station 4932,16 East Harding Way,Stockton A L4ay 10,2001 An extended steptest was performed on each of the two wells Approximately 15 P PP Y ' inches of mercury (in Hg) vacuum was induced for up to 65 minutes, first at MW-4, then at SVE-1 on February 12, 2001 MW-4 and SVE-1 were simultaneously used as extraction wells on February 13-16, 2001 Physical and chemical parameters including applied vacuum, flow rate, and FID readings were monitored throughout each test on the test well Vacuum gauges were placed at nearby monitoring wells in order to monitor the negative pressure gradient induced by each respective extraction well MPE test data is summarized in Tables 2 through 6 After one hour, approximately halfway through the test, and at the end of the MPE test, ' influent vapor samples were collected from each of the extraction wells Samples were analyzed for TPHg, benzene, toluene, ethylbenzene, xylenes (BTEX compounds), and methyl-cert-butyl ether(MtBE) by EPA Methods 8015 and 8020 Results of these analyses are presented in Table 5 Certified analytical reports and chain-of-custody documentation data are presented as Attachment B ' MPE FEASIBILITY TEST RESULTS Applied Vacuum and Vapor Extraction Flow Rates ' During the MPE tests, the applied vacuum on test wells ranged from 5 5 in Hg to 25 in Hg, and vapor extraction flow rates ranged from 32 7 standard cubic feet per minute (scfm) to 99 2 scfm Vapor extraction flow rates were limited due to high influent hydrocarbon concentrations, the FID readings collected from the vapor extracted from all wells were greater than 10,000 parts per million (ppm) throughout the test Vapor ' extraction flow rates and vacuums observed during the pilot tests are presented in Tables 2 through 4 ' Induced Vacuum Readings Induced vacuum readings were obtained from observation wells during each test The ' induced vacuum data collected during the tests are presented 1n Tables 2 through 4 During the tests, induced vacuum responses were observed in wells up to 89 feet away from the test well Induced vacuum was observed in well MW-3 during the test of well ' MW-4, and in wells MW-3 and MW-4 during the test of well SVE-1 During the test of wells SVE-1 and MW-4 combined, induced vacuum responses were observed in observation wells MW-1 and MW-3 ' Soil Vapor Analytical Results The field influent TPHg concentrations measured while extracting vapor were greater ' than the maximum detection limit of the FID (10,000 ppmv -Tables 2-4) The laboratory reported TPHg, benzene, and MtBE at maximum concentrations of 5,630 ' ppmv (MW-4/SVE-1A), 660 ppmv (MW-413), and 22,100 ppmv (MW413), respectively Laboratory analyses of samples collected during the WE test are summarized in Table 5 The laboratory analytical results and chain-of-custody records ' for air samples are included in Attachment B ' ARCO 4932/MPE test doc