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7 LDmu Nc G. Bgawr.Jn. <br /> ovw <br /> =AIIFORNrA APR 12 2013 <br /> SARI ATTHEw RI ORDR10UEZ <br /> Water Boards FNVIq(1NMFNTAI PRnTFfTlnl: <br /> Central Valley Regional Water Quality Control oarcf <br /> 11 April 2013 <br /> Mr. Donald Rodgers <br /> 11900 South Union Rd. <br /> Manteca, CA 95336 <br /> DOCUMENT REVIEW, THE TRANSMISSION STORE, 515 WEST CHARTER WAY, <br /> STOCKTON, SAN JOAQUIN COUNTY(REGIONAL BOARD CASE # 390891) <br /> 1 reviewed the Remediation Status Report - Third and Fourth Quarters 2012 (Report) and the <br /> Response to Report Comments (Email), received 29 March 2013 and 9 April 2013, respectively <br /> from your consultant Advanced GeoEnviron mental Inc. (AGE). The Report provides the results <br /> of the soil vapor extraction (SVE) and air sparging (AS) soil and groundwater remediation <br /> conducted from July 2012 to December 2012. Approximately 82.1 lbs. (13 gallons) of total <br /> petroleum hydrocarbons as gasoline (TPHg) were removed as soil vapor in 144 days of SVE <br /> operation after AGE restarted the treatment system in July 2012. The Report recommends <br /> continued operation of SVE/AS system as configured, and discontinuation of the monthly vapor <br /> sampling, due to low to non-detect influent vapor concentrations. <br /> On 8 April 2013, 1 contacted William Little of AGE by phone and discussed the Report mass <br /> removal results and recommendations. During the call, I questioned why the SVE portion of the <br /> system was still running when vapor concentrations were non-detect, and why groundwater <br /> concentrations were not declining across the plume. The original Shaw design for the existing <br /> AS wells was that air would migrate from the deeper AS wells upward into the shallow plume <br /> and eventually reach the highest concentrations at MW-7S. However, MW-7S is showing a <br /> steadily increasing concentration trend, with TPHg, 60,000 micrograms per Liter (ug/L); <br /> benzene, 7,600 ug/L; toluene, 1,700 ug/L; ethylbenzene, 900 ug/L; and xylenes, 2,420 ug/L <br /> during the Fourth Quarter of 2012. <br /> During our discussion, AGE recommended installation of two additional shallow air sparge wells <br /> screened at 45' below ground surface (bgs) near MW-7S, to remediate the shallow groundwater <br /> plume. We also discussed AGE's suggestion for batch groundwater extraction, including the <br /> limited space for onsite treatment with City disposal permit costs versus bulk water transported <br /> to a treatment facility. AGE stated that the State Water Resources Control Board Underground <br /> Storage Tank Fund recently approved an additional $75,000 this fiscal year to conduct <br /> remediation at the site, and that the new wells could be installed within the budget. <br /> I requested that the SVE portion of the system be shut down immediately, to conserve funds (a <br /> savings of $450 to $550 monthly for utilities, plus monthly vapor sampling laboratory costs), and <br /> also requested an email response with an evaluation of the current SVE/AS system <br /> KARL E. LONGLEY SCD, P.E., CHAIR � PAMELA C. CREEDON P.E.. DCEE, EXECUTIVE OFFICER <br /> 11020 Sun Center Drive#200.Rancno Cordova,CA 95670 I wwwwaterboarcis ca gov/centralvalley <br /> ID nEGyC c PA- <br />