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REMEDIALACTION PLAN 1805 South EI Dorado Street,Stoddon Caldom a 4 2 Vapor Extraction tVapor extraction enhances natural volatilization and diffusion of volatile petroleum hydrocarbons in the vadose zone and will also increase the diffusion and volatilization of Petroleum hydrocarbons from groundwater Vapor extraction will also increase the oxygen content of the soil vapor in the vadose zone and can increase the dissolved oxygen concentrations in the groundwater which may increase natural biodegradation rates Important elements for effective vapor extraction include high hydrocarbon removal rates, relatively homogeneous soils, and a good radius-af-influence The borings and vapor extraction testing performed at the site confirmed these factors The selected remediation technology for the site is soil vapor extraction using a 250 standard cubic feet per minute (scfm) airflow capacity vacuum pump (blower) Emissions control is required prior to discharge to the atmosphere 4 3 Pilot-scale Vapor Extraction Test IOn 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 IJoaquin Valley Unified Air Pollution Control District (SJVUAPCD) requirements Data from the test are included in Appendix C While extracting from well VEW-1 (screened to remediate the former UST backfill material, from 5 to 15 feet bgs), vacuum 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 (Figure 11A) 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) IWhile extracting from well VEW-2 (screened to remediate native soil below the former UST backfill, from 15 to 35 feet bgs), 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 (Figure 11 B) The calculated TPH as gasoline removal rate from this well was 40 pounds per day at an average flow rate of 24 cfm 91 044A RAP 5 I