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' Off-Site Groundwater Investigation Work Plan Page 5 Rainwater Car Wash,Manteca, California 95336 May 30,2012 ' Land Complex(DLC).The DLC soils generally consist of wind-modified alluvium derived from granitic rock sources. Soil in the DLC is classified as somewhat excessively drained. ' 4.2 Regional and Local Hydrogeology The Modesto, Riverbank,and Turlock Lake Formations and overlying Recent alluvium are the principal source of ' domestic groundwater in the 13,500-square-mile San Joaquin Valley Groundwater Basin(Basin 5-22). This basin is drained primarily by the San Joaquin River,which is located approximately 2.5 miles to the west. ' Based on regional information from Lines Of Equal Depth To Groundwater and Lines of Equal Elevation Of Groundwater, published by the San Joaquin County Flood Control and Water Conservation District between 1975 and the present,the depth to groundwater at the property has generally fluctuated between 15 and 25 feet bgs; ' regional groundwater flow direction has generally been oriented toward the northwest. Based on vertical soil profiles in soil boring logs acquired during site assessments,supplemented by CPT data, dense to very dense, unconsolidated,poorly graded, fine to medium sand and silty sand were generally identified at depths between surface grade and 10 feet bgs,between 15 and 50 feet bgs,between 65 and 117 feet bgs,and between 133 and 170 feet bgs.Conversely, fine-grained,sandy silt was generally identified at depths between 10 feet and 15 feet bgs,between 50 and 65 feet bgs, and between 117 and 133 feet bgs. Based on the initial CPT data,AGE informally identified four potential hydrogeologic flow units located at depths between 15 and 47 feet bgs, 58 and 92 feet bgs, 102 and 115 feet bgs,and 128 and 150 feet bgs. Based on the second quarter 2012 groundwater monitoring results,static groundwater lies at depths between 14.57 and 16.96 feet beneath the site.Groundwater flow was calculated toward the north-northwest direction with a general hydraulic gradient of 0.0024 feet per foot. ' 5. PROPOSED WELL INSTALLATION ' 5.1 Summary of Activities The proposed work includes the installation of three dual-nested groundwater monitoring wells to depths of 30 and 70 feet each.Accordingly, soil samples will be collected at 5-foot intervals from ground surface to terminal depth and logged for lithologic analysis only. The work will be performed under the supervision of a PG licensed in California in compliance with the requirements of the Geologist and Geophysicists Act, Business and Professions Code sections 7800-7887.The following sections describe the installation activities in detail. 5.2 Fieldwork Preparation ' 5.2.1 Health and Safety Plan AA&A prepared a site-specific CHSP, which will be implemented according to the Occupational Safety and ' Health Administration(OSHA)requirements(29 Code of Federal Regulations [CFR] 1910.120)to address the proposed scope of work(Appendix B). Requirements and guidelines for worker safety and hazard identification during all phases of the drilling activities are included in the SHSP.The on-site health and safety officer will be responsible for implementation of the CHSP.A health and safety meeting will be conducted at the beginning of ' the each day during field activities. ' Ami Adim ' &Associ lte.Anc.