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r r <br /> 4' <br /> Mr. Stephen Schneider <br /> . Quarterly Summary Report <br /> June 5, 1992 <br /> Page 2 <br /> SOIL REMEDIATION <br /> In early April 1992,SEACOR installed a soil vapor extraction system at the site. The as-built system <br /> consists of a single vapor extraction well screened from 20 to 40 feet below ground surface, a trailer- <br /> mounted regenerative blower with a 200 cubic feet per minute (CFM) capacity, and two in-line <br /> granular activated carbon vapor phase treatment vessels(2,000 pound and 200 pound capacity). The <br /> vapor extraction and treatment equipment are all housed within a fenced compound. <br /> SEACOR began operating the soil vapor extraction system on April 15, 1992. Prior to and during <br /> system start-up, a representative from the San Joaquin Valley Unified Air Pollution Control District <br /> (SJVUAPD) inspected the system and provided SEACOR with an approval to operate. As of May <br /> 25, 1992, an estimated 189 pounds of petroleum hydrocarbons have been removed from the <br /> subsurface soils. SEACOR is currently monitoring system operation in accordance with the <br /> requirements of the permit to operate from SJVUAPD. <br /> SEACOR anticipates operating the soil vapor extraction system for an initial period of six months. <br /> If soil vapor removal rates have decreased significantly and remain stable following six months of <br /> operation, SEACOR will collect subsurface soil samples to evaluate residual hydrocarbon <br /> concentrations remaining in subsurface soils underlying the former underground storage tank. <br /> The non-detectable to very low levels of TPHg and BTEX reported during the most recent <br /> groundwater monitoring event (May 1992) suggest that soil vapor extraction may be enhancing <br /> volatilization of petroleum hydrocarbons from groundwater underlying the site. This conclusion will <br /> be evaluated further with additional groundwater monitoring data. <br /> Please feel free to contact me at (415) 296-7877 if you have any questions or comments regarding <br /> this letter. <br /> Sincerely yours, <br /> Science & Engineering Analysis Corporation <br /> Bruce E. Scarbrough, R.G. #4931 <br /> Principal Geologist <br /> BES/bhs <br /> Table 1: Current and Historical Groundwater Quality Data for Well MW-1A <br /> • MAY.QSR <br /> 50014-001-05 MK01 <br />