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ATC ENVIRONMENTAL • GEOTECHNICAL BUILDING SCIENCES • MATERIALS TESTING 1117 Lone Palm Avenue, Suite 20IB Modesto, CA 95351 Telephone 209-579-2221 Fax 209-579-2225 www.atcgroupservices.com Underground Utility Locating and Clearance In advance of field activities, ATC will mark the locations of the proposed borings in accordance with the Underground Service Alert (USA) guidelines, and notify USA of upcoming subsurface activities in order for existing underground utilities in the area of proposed work to be located and contact avoided. ATC will also contract a private utility locator to confirm the locations of underground utilities in the vicinity of the drilling locations. Prior to use of drilling equipment, the borehole locations will be hand cleared and/or air knifed to a minimum depth of 5 feet bgs. Boring Advancement ATC will contract with a C-57 licensed drilling company to advance two hydropunch borings to approximately 65 feet bgs to collect groundwater samples between 45 and 65 feet bgs. The borings will be advanced at two locations along the east side of San Joaquin Street near former borings SB10 and SB16. Proposed boring locations are shown on Figure 2. Groundwater samples will be collected from the boreholes using a modified HydroPunch® sampler. Prior to groundwater sampling, a water level meter will be used to confirm that the drive rods do not contain water. The sampler will then be driven to approximately three feet below the desired sampling depth, and retracted three feet to expose the disposable schedule 20 polyvinyl chloride (PVC) screen and allow for groundwater to enter the HydroPunch® sampler. The water sample will be collected by lowering a %-inch diameter stainless steel bailer through the drive rods to groundwater. The groundwater will be bailed from the drive rods and decanted from the bailer into 40-milliliter (ml) volatile organic analysis (VOA) vials. Following the collection of the sample, the drive rods will be retracted, leaving the disposable drive tip and four-foot length of PVC well screen in the hole. Following completion, the borings will be grouted through the drive rods from the total depth explored to surface grade with neat cement. ATC anticipates that at least two groundwater samples will be collected from each boring at screened intervals between 45 and 65 feet bgs. Following groundwater sample collection, the borings will be backfilled with neat cement grout to the ground surface. Drill cuttings, if any, will be stored on-site in 55-gallon containers pending laboratory results after which disposal arrangements will be made. Laboratory Analysis Groundwater samples collected will be submitted for chemical analysis under chain-of-custody documentation to a California state certified laboratory. Samples will be analyzed for total petroleum hydrocarbons as gasoline (TPHg), benzene, toluene, ethylbenzene, and total xylenes (BTEX), and fuel oxygenates, including methyl tertiary butyl ether (MTBE) and tert butyl alcohol (TBA), using EPA Method 8260. 2