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Multi-Phase Extraction Pilot Test Report&Remedial Design i Thrifty Stadon No 171 Page 7 Slacktoa,California November 30,20I0 e + Approximately 100 feet of underground piping from the remediation system compound to the sewer discharge line. Pneumatic downhole groundwater pumps along with an air compressor for pump operation would be re-installed (both have been removed from the site), The estimated cost of purchasing and installing the complete groundwater treatment system is $60,000. Design drawings of the proposed system are included in Figures 3 though 5. 4.0 RESULTS AND CONCLUSIONS From October 25 to October 30, 2010, MPE pilot testing was performed at the site to determine its effectiveness at remediating hydrocarbons from subsurface soil and groundwater. Pilot testing consisted of groundwater and vapor from wells EW-51), EW-5S and TB-7, both collectively and individually. Idle wells were utilized as observation wells during pilot testing activities to determine effectiveness. The MPE system operated for approximately 120 hours and continually combusting VOC vapors at temperatures above 1400 degrees Fahrenheit and extracted a total of 12,960 gallons of groundwater for treatment and discharge to the sanitary sewer system at an average rate of 1.8 gallons per minute. A summary of MPE pilot test results is included in Table 7. At the completion of pilot testing, and based upon system parameters and analytical results, it was calculated that approximately 31 pounds of hydrocarbon fuel contaminants were removed from the subsurface of the site through vapor extraction at average removal rate of 0.25 lbs/hour. Hydrocarbon removal rate increased to 0.58 lbs/hour during extraction from wells EW-5D,EW-5S and TB-7. Influent concentrations, as measured in the field by photo-ionic detector (PID), ranged from 484 ppm during extraction from well EW-51) to 63 ppm during extraction from well EW-55. Influent TPHg concentrations according to analytical laboratory results ranged from 27 ppm at the beginning of extraction from EW-5S to 287 ppm, at the end of extraction from all three wells. Influent hydrocarbon concentrations based on PID readings are presented in Graphs I through 4. Vacuum response measured at the observation wells ranged from 2.25 inches of water(T13-12W during extraction from TB-7) to zero vacuum response from some observation wells during testing. Vacuum response and groundwater drawdown varied based on direction and screen interval of the extraction and observation wells. Radius of influence of vapor is conservatively estimated as 55 feet (Figure 6). Vacuum response and groundwater drawdown readings observed during pilot testing indicate that MPE system operation is capable of removing soil vapor from subsurface soil. environ strategy consultants, inc.