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California gional Water Quality Con l Board <br /> Central Valley Region <br /> Karl E. Longley,ScD,P.E.,Chair <br /> r ` <br /> Linda S. Adams � ,..a Arnold <br /> S'ecremryfor Sacramento Main Offiova,C V E_nj D <br /> 11020 Sun Center Drive 8200,Rancho Cordova,Califome 1 u v �C V Schwarzenegger <br /> Environmental Phone(916)464-3291 •FAX(916)464-4645 Governor <br /> Protection <br /> http://www.waterboards.ca.gov/centralvalley <br /> JAN 1 12008 <br /> 10 January 2008 <br /> ENVIRONn4EN�HEALTH <br /> PE4w,I, -E ,%.0 S <br /> Mr. Don Pratt, Environmental Business Manager Mr. Gurpreet and Ms. Kuldeep Dhat <br /> Atlantic Richfield Company 501 S. Cherokee Avenue <br /> P.O. Box 1257 Lodi 35240 <br /> San Ramon 94583 <br /> DOCUMENT REVIEW, ARCO #0760, 225 S. CHEROKEE LANE, LODI, <br /> SAN JOAQUIN COUNTY (REGIONAL BOARD CASE # 390330) <br /> 1 reviewed the Quarterly Groundwater Monitoring Report Fourth Quarter 2007 (Report), <br /> received 8 January 2008 from your consultant Secor International Incorporated (Secor). The <br /> Report provides the results of the 8 October 2007 groundwater monitoring event, and requests <br /> a monitoring frequency reduction for monitoring wells MW-4 (to annually) and MW-6 through <br /> MW-9 (to semi-annual). The Report states monitoring results of these wells have been non- <br /> detect since installation. <br /> The Report also states the maximum groundwater concentrations were: Total Petroleum <br /> Hydrocarbons as gasoline (TPHg), 160 micrograms per Liter (ug/L); benzene, 0.55 ug/L; <br /> xylenes, 6.1 ug/L; methyl tert-butyl ether (MtBE), 20 ug/L; and 1,2-dichloroethane, 5.8 ug/L. <br /> Comments: <br /> 1. 1 concur to the reduction in sampling frequency request for the following four wells <br /> (enclosed Figure 3) with the following conditions: <br /> • Well MW-4 will be sampled for all of the petroleum hydrocarbon constituents <br /> during the first quarter 2008 and then annually during the second quarter of each <br /> year for all of the petroleum hydrocarbon constituents. If there is any detection <br /> of a petroleum hydrocarbon constituent in sampling of MW-4, then quarterly <br /> sampling will be re-instituted for all of the petroleum hydrocarbon constituents. <br /> • Wells MW-7, MW-8, and MW-9, which were installed three quarters ago, will be <br /> sampled for all of the petroleum hydrocarbon constituents during the first quarter <br /> 2008 and then semi-annually for all of the petroleum hydrocarbon constituents <br /> during the second and fourth quarters of each year. If sampling results of either <br /> MW-7, MW-8, or MW-9 report a petroleum hydrocarbon constituent, then <br /> quarterly sampling for that well (reporting a petroleum hydrocarbon constituent) <br /> will be re-instituted for all of the petroleum hydrocarbon constituents. <br /> California Environmental Protection Agency <br /> ped Recycled Paper <br />