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URS 0 • Ms.Lori Duncan,REHS Page 6 of 8 San Joaquin Environmental Health Department June 9,2005 Task 5—Remediation System Operation and Reporting Performance of the remediation system will be included in the site quarterly monitoring reports. The remediation system will be operated until SJCEHD remediation goals are achieved or until the remediation effort is shown to be no longer technically or economically feasible. Throughout the life of the system, operations will be monitored to verify permit compliance and to meet reporting requirements. Groundwater monitoring and sampling will continue to be performed at the site, as required. System efficiency reporting will include summaries of mass extracted, mass extraction rates, and any modifications to system operation that may have changed mass extraction rates. Groundwater concentrations will be compared to their respective remediation goals to evaluate progress toward the termination,of remediation at the site; influent vapor concentrations will be used to evaluate progress of remediation of impacted soils. Groundwater Monitoring Well Installation Monitoring wells will be installed in borings drilled with a 8-inch OD HAS-equipped drill rig. Soil samples will be collected at 5-foot intervals during the drilling of the borings using a modified California split-spoon sampler. Soil samples will be used for lithology, and screened with a PID for possible laboratory analysis. One sample from each boring will be submitted for laboratory analysis. A URS geologist will log the soils according to the Unified Soil Classification System. Total depth for the proposed monitoring well borings will be approximately 30-feet bgs (10 feet into groundwater). Proposed monitoring well locations are shown in Figure 2. Monitoring wells will be constructed using 2-inch OD, schedule-40, flush-threaded PVC well casing. The wells will be constructed with 15 feet of screen set across the water table, so that 10-feet of screen is submerged below the water table (approximately 15 feet to 30 feet bgs). A Monterey No. 2/12 silica sand filter pack(sand), or equivalent, will be installed from 6 inches to 3 feet above the screen. A 2 foot bentonite seal will be installed atop the sand, and grout will fill the remaining annular space to the surface. Monitoring wells will be completed at the surface with a 12-inch traffic-rated flush-mounted well box set in concrete. The wells will be completed under the direction of a URS geologist. Exact screen intervals will be determined in the field by the URS geologist. Well completion details will be presented on the boring logs. A minimum of 72 hours after installation, the monitoring wells will be developed by rigorously surging over the length of their respective screen intervals and by purging a minimum of 10 casing volumes of water from each well. Monitoring wells and remediation wells will be surveyed to northing and easting coordinates and mean sea level by a licensed surveyor. KAWpmcess\15 BP ARCO\02168\2005 System Installation\SVE-AS Workplandoe