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San Joaquin County of Public Works January 15, 1999 Workplan for Site Assessment Task 2: Health and Safety Plan Modification A health and safety plan (HSP) will be prepared for the proposed scope of work. The HSP is designed primarily to minimize exposure of TEM personnel and its subcontractors to potentially hazardous materials. The plan will be prepared under the direction of the Corporate Health and Safety Officer and will be implemented in the field by the Site Safety Officer. Task 3: Drilling and Soil Sampling Three (3) borings will be drilled out using 10-inch outside diameter (OD) hollow stem augers to a maximum depth of approximately 75 feet bgs. Two (2) hand auger borings will be advanced to approximately 15 feet bgs. Samples collected from the borings will be used to assess the vertical and lateral impact in the soil. Soil samples will be collected at five-foot intervals and/or where changes in lithology are observed. Samples will be collected in 2-inch diameter by 6-inch long brass cylinders that have been decontaminated, and the ends will be covered with Teflon and capped with polyethylene caps. A TEM geologist, trained and supervised by a registered geologist, will describe soil samples using the Unified Soil Classification System. The geologist will use a Photoionization Detector (PID) to screen the soil samples in the field for the presence of volatile organic compounds (VOCs) and to select soil samples for laboratory analyses. Task 4: Groundwater Well Installation and Development If groundwater is encountered, the boring will be advanced an additional 15 feet for the installation of monitoring wells. The depth to groundwater at the site is estimated at approximately 50 feet bgs. Each well shall be constructed of flush jointed, threaded, 4-inch, Schedule 40 polyvinyl chloride (PVC) slotted screen (0.020) and blank casing. The wells will be screened from approximately 35 to 70 feet bgs. Blank casing will be used to construct the remainder of the well to ground surface. A filter pack consisting of No. 3 Monterey sand will be placed at the top of the screened interval. The annular seal shall consist of a minimum 3- foot thick bentonite seal placed directly above the filter pack. The remaining annular space will be grouted to approximately one (1) foot bgs. The surface completion of each well shall consist of a traffic-rated well box installed to grade. The newly-installed groundwater monitoring wells will be surged and developed using a development rig. Surging will continue until turbidity readings reach a value of 10 NTU or less, or a minimum of five (5) well volumes of water have been removed from each well, as per regulatory guidelines. Development water will be contained in DOT-approved 55-gallon drums. 4 Ti'1iT