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Y <br /> ATC Associates Inc. <br /> *7 Lone Palm Avenue, Suite 201 <br /> Modesto, California 95351 <br /> 209-579-2221 <br /> Fax: 209-579-2225 <br /> ASSOCIATESCVAY4; <br /> I NC . <br /> Petroleum Hydrocarbons as Gasoline (TPHg), and an estimated 823.39 pounds of Benzene, <br /> Toluene, Ethylbenzene, and Total Xylenes (BTEX) constituents. <br /> GROUNDWATER MONITORING ACTIVITIES <br /> On May 19, 2009, the State Water Resources Control Board (SWRCB) approved Resolution <br /> 2009-0042. A part of this resolution directed regulatory agencies with delegated oversight <br /> authority to institute a reduction in frequency of groundwater monitoring and sampling from <br /> quarterly to semi-annually. <br /> In correspondence dated April 29, 2009, the San Joaquin County Environmental Health <br /> Department (SJCEHD) reiterated its approval of the annual sampling of wells MW3 through <br /> MW7 originally approved in correspondence dated November 19, 2003. Additionally, the <br /> SJCEHD stated that monitoring wells MW1 and MW2 are to be sampled semi-annually. <br /> Changes to the groundwater monitoring program are indicated in the following schedule: <br /> First Quarter Third Quarter <br /> MW1, MW2 MW1, MW2, MW3, MW4, MW5, <br /> MW6, rA W-} <br /> Consequently, the next semi-annual groundwater quality sampling event at this site will occur <br /> during the third quarter of 2009. <br /> REMEDIATION SYSTEM ACTIVITIES <br /> Soil Vapor Extraction System <br /> The SVE system was shut down on February 13, 2009, and the subsurface conditions were <br /> allowed to stabilize and equalize in preparation for a planned rebound test. In a letter dated <br /> April 29, 2009, SCEHD recommended the SVE system be restarted. ATC conducted the SVE <br /> rebound test July 14, 2009 and is awaiting laboratory data. ATC will report on its findings in <br /> the site's Third Quarter Status Report. <br /> RECOMMENDATIONS <br /> ATC makes the following recommendations: <br /> • Reduce the frequency of groundwater sampling at the site to the first and third quarters, <br /> changing the monitoring frequency of MW1 and MW2 to semi-annual and MW3, MW4, <br /> MW5, MW6, MW8, MW9, and MW10 to annual monitoring. Continue to analyze all <br /> samples for GRO by EPA Test Method 8015M and for BTEX chemicals and fuel <br /> oxygenates by EPA Test Method 8260B. <br /> • Evaluate the results of the recently completed rebound testing. <br /> 8:lenvironmentaiNG2577103\quarterly12009 Q2.doc 3 <br />