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PROBLEM ASSESSMENT REPORT 1606 South EI 1)orado Street Stockton California The analytical results are summarized in Table 6 The laboratory reports and ' chain-of-custody form are included in Appendix E Concentrations of TPH, as gasoline, and benzene reported in Table 6 are also shown on Figure 8 ' 3 6 Drill Cuttings and Monitoring Well-Purge Water All drill cuttings were stored temporarily on site, on and under plastic sheeting, Pending laboratory analysis of one two-to-one composite soil sample collected from the stockpile to characterize the material for disposal. Following receipt of the laboratory results, the drill cuttings were transported, by a licensed hauler, to the BFI Vasco Road, Class III, landfill in Livermore, CA Rinsewater and purge water generated during well sampling and drilling was stored temporarily on site in DOT- approved 55-gallon drums, pending laboratory analysis of the boring samples r Following receipt of the laboratory results, the water was transported to the Gibson recycling facility in Redwood City, CA 3 7 Vapor Extraction Testing On May 12, 1993, a pilot-scale soil vapor extraction (SVE) test was performed on vapor extraction wells VEW-1 and VEW-2 to assess the feasibility of this technology for soil and groundwater remediation An internal combustion engine was used to create a vacuum in each well for 2 to 4 5 hours, while the other wells were monitored with pressure gauges to assess the subsurface extent of the induced vacuum (radius of influence) Average flow rates, pressure, and temperature measurements were used to estimate hydrocarbon removal rates The vapors extracted were burned in the engine, consistent with San Joaquin Valley Unified Air Quality Management District (SJVUAQMD) requirements Data from the test are included in Appendix F While extracting from well VEW-1 (screened to remediate the former UST backfill, from 5 to 15 feet bs), vacuum I influence of at least 0 02 inches of water was measured as far as 57 feet away in well MW-2, although no influence was noted in MW-5, located 45 feet from VEW-1 The estimated radius of influence is approximately 50 feet The calculated hydrocarbon (TPH as gasoline) removal rate from this well was 7 6 pounds per day at an average flow rate of 8 2 cubic-feet-per-minute (cfm) While extracting from well VEW-2 (screened to remediate native soil below the former UST backfill, from 15 to 35 feet bs), vacuum influence of at least 0 01 inches of water was measured as far as 116 feet away in well MW-4, although no influence was noted in MW-6, located 110 feet from VEW-1 The estimated radius of influence is approximately 100 feet The calculated TPH as gasoline removal rate from this well was 40 pounds per day at and average flow rate of 24 cfm 91 044A PAR 8 I