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i Work Platrbr Additional Site Assessment Jimco Truck Plaza I C A M B RI A 1022 Frontage Road Ripon, California j May 18, 2005 uppermost perforation. The sandpack will be sealed with at least 2 feet of hydrated bentonite chips. The remaining annular space will then be sealed with cement grout. The wellhead will be completed below grade and will be protected by a traffic-rated monitoring well vault with a water-tight lid. j The groundwater monitoring well will be developed approximately 72 hours after installation is complete. The well will be intermittently surged with a surge block, and groundwater will be i evacuated using a bailer or submersible pump until the groundwater is visibly clear and/or has a low turbidity. During purging, measurements of temperature, pH, conductivity, and turbidity will be recorded on monitoring well purge and development forms. The new groundwater monitoring well will be sampled as part of the ongoing quarterly monitoring program at the site. 5.3 Depth Discrete Groundwater Sampling Depth discrete groundwater samples will be collected in a soil boring drilled using hollow stem augers advanced on the west side of the former USTs. Grab groundwater samples will be collected at depths of approximately 30, 45, and 60 feet bgs to delineate the vertical extent of hydrocarbons and fuel` S �Aoxygenates in groundwater. Actual sample depths are subject to change should unexpected conditions alfo/ be encountered in the field(i.e. low yield aquifer,etc.). Depth discrete groundwater samples will be collected using the Hydropunch®sampling system. The Hydropunch® sampler is driven approximately 4 ft below the bottom of the augers whereupon the approximately 1 ft of screen casing is exposed to allow groundwater to infiltrate hydrostatically from the formation. Clean disposable tubing connected to the sampler is then used to collect a depth discrete groundwater sample. After collecting each sample, sampler is. retrieved to the surface, decontaminated, and prepared for the next Hydropunch®groundwater sample. Upon collecting-the final sample, the borehole will be tremie grouted with neat cement and completed at the surface to match the existing grade. 5.4 Well Survey Upon completing the drilling activities, Cambria will retain the services of a licensed surveyor to I survey the coordinates and elevations of the new monitoring well and soil boring, as well as unsurveyed wells MW-9 and EW-1. Survey data will be tied to a local benchmark. I 5.5 Chemical Analysis Select soil and depth discrete groundwater samples collected during the site assessment activities will be analyzed for TPHg by modified EPA Method 8015C,TPHd with silica gel cleanup by modified 8