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California Regional Water Quality •Control Board Central Valley Region Robert Schneider,Chair 0 Winston H.Hickox Gray Davis Secrelaryfor Sacramento Main Office (� �/p� Governor E Protectionoal 3443 Rou�r Road,Suite A,Saet Address: ov emento,California 95827-3003 1 REG L�� J �D Phone(916)255-3000•FAX(916)255-3015 Il u JUN 17 2002 13 June 2002 ENVIRONMENT HEALTH Mr.Dale Gillespie PERMIT/SERVICES Geweke Land Development and Marketing PO Box 1210 Lodi,CA 95241 REVIEW CONE PENETROMETER TESTING REPORT ADDENDUM—MAY 2002, GEWEKE PROPERTY, 16 SOUTH CHEROKEE LANE,LODI,SAN JOAQUIN COUNTY, CLEANUP AND ABATEMENT ORDER (C&A)NO. 93-701 Board staff reviewed the 24 May 2002 Cone Penetrometer Testing(CPT)Report Addendum-May 2002(CPT Addendum)submitted by Advanced GeoEnvironmental,Incorporated(AGE)on behalf of Geweke Land Development and Marketing(Geweke). The CPT Addendum was prepared to address comments submitted in our letter dated 24 April 2002. The CPT Addendum presents the following: • A discussion of petroleum impacted soils encountered from two to four feet in CPT boring CPT-2; • A discussion of total petroleum hydrocarbons as gasoline(TPHg) identified in groundwater grab samples; • A revised geologic cross section with lithology and well completion data from extraction well EW-1 and monitoring wells MW-8 and MW-12; and • Recommendations to prepare a workplan for installation of clustered monitoring wells downgradient of the site. As presented in the Cone Penetrometer Testing Report-December 2001 and the CPT Addendum,AGE identified three hydrostratigraphic units at the subject site. Unit 1 extends from 45 to 65 feet and includes sand and minor silt lenses,Unit 2 extends from 65 to 95 feet and includes predominantly sand and gravelly sand lenses, and Unit 3 extends from 95 to 140 feet and includes predominantly silt with minor sand lenses. The water table has fluctuated between 55 and 80 feet between 1986 and 2001,and it is currently at approximately 55 feet in Unit 1. TPHg was identified in CPT groundwater grab samples from multiple intervals ranging in depth from 72 to 134 feet(Units 2 and 3),and benzene was only detected in hydrostratigraphic Unit 2. Therefore,based on this added information,AGE proposes to prepare a workplan to install two monitoring well clusters to verify the lateral and vertical extent of groundwater contamination downgradient of the site. Two well screen intervals are proposed near monitoring well MW-8, and three well screen intervals are proposed near CPT-3. One well will be completed in Unit 1 at 50 to 70 feet,two wells will be completed in Unit 2 at 75 to 80 feet and 80 to 90 feet,and California Environmental Protection Agency 0 Recycled Paper The energy challenge facing California is real. Every Californian needs to take immediate action to reduce energy consumption. For a list of simple ways you can reduce demand and cut your energy costs,see our Web-site at http://www.swreb.ca.gov/mgcb5