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' FINAL F"/U]I UM PLAN 14800 West Frontage Road Manteca CalNornla 2.7.1 Equipment ' Equipment used in the vapor extraction pilot test included an in-line particulate air filter, an air/water separator, a 10-horsepower regenerative blower, a portable electric generator, pressure gages, airflow meters, temperature indicator, and a portable ' photoionization detector (PID) 2.7.2 Procedure For the test, a portable vapor extraction system (VES) was transported to the site and located adjacent to monitoring well MW-4 The VES consisted of two Rotron DR505 ' regenerative blowers connected in parallel and discharging to the atmosphere The VES was monitored at the intake to the assembly for temperature and pressure, and at the exhaust for temperature, pressure, and flow rate Reducing the atmospheric pressure in the sod was achieved by the blower assembly creating a pressure drop in the sods around well MW-4 This resulted in the development ' of a cone of pressure depression (CPD) The CPD develops radially outward from a well to the point where pressure in the subsurface equals atmospheric pressure The CPD causes an airflow toward the well Air and gases collecting in the well casing flow through ' the blower assembly The exhaust from the blower assembly is directed through the exhaust stack 2.7.3 Test Situations and Results 1 The pilot test was conducted during a 1-3/4-hour session No fresh air was admitted artificially into the system The pressure drop was measured by connecting pressure gauges to outlying monitoring wells and noting the change in pressure The blower assembly was monitored for organic vapors by a PID at the intake to the assembly and on the exhaust stack. The system airflows were monitored at the blower exhaust Measurements of air temperatures and pressures were collected at the intake to the blower assembly and at the blower exhaust Air samples were collected at the intake assembly and submitted to a state-certified laboratory for analysis by GC-FID/EPA Methods 5030/8015. Air samples were collected at the end of the test Data from the pilot test is summarized in Table 5 Results of analytical testing are included ,n Appendix F The radius of influence induced by the vapor extraction pilot test on well MW-4 was measured at wells MW-1 through MW-3 and MW-5 through MW-9 An average influence of -0 15-inches of water was measured at well MW-1, at a distance of approximately I 73 feet from well MW-4 An average influence of -0 11-inches of water was measured at well MW-2, approximately 80 feet from well MW-4 The measured airflow yield from well MW-4, together with the calculated radius of influence on the surrounding monitoring wells, indicate well MW-4 would be a viable candidate for in-situ vapor extraction 90-097A FRP -6-