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3.2 MONITORING WELL INSTALLATION t Thirteen (13) monitoring wells are proposed to be installed at the locations previously mentioned and shown on Plate 2. The proposed well locations have been selected to assess groundwater ' conditions upgradient and downgradient of the existing surface impoundments, landscape areas, and land application areas and to best assess groundwater gradient during the time of sampling. The monitoring wells will be drilled into first encountered groundwater. Based upon available ' information and previous experience at the site we anticipate groundwater in the vicinity of the project site to be present at a wide range of depth of approximately 30 to greater than 100 feet below the ground surface (bgs), with a regional groundwater flow direction to the east/northeast. An intermittent stream bisects the site from the southwest to the northeast and may act as a hydrogeologic barrier for shallow groundwater flow direction. Each of the 13 soil borings will be drilled with a truck mounted drill rig equipped with 8-inch hollow stem augers. During advancement of the soil borings, soil samples will be collected at five- foot intervals for lithologic classification. Lithologic classification will be based on the Unified ' Soil Classification System (USCS). An experienced environmental engineer or geologist will log the soil borings. All equipment used in the drilling and installation procedures will be cleaned and/or decontaminated as described in Appendix B. ' Following completion of drilling the soil borings, a clean 2-inch diameter PVC well will be installed in each of the borings. The soil borings will be advanced approximately 10 to 15 feet into groundwater. The wells will be constructed with schedule 40 PVC, a 10 to 15 foot long 0.010 inch screened section surrounded by and covered by a sand filter pack(#2/16), 3 to 5 foot thick bentonite ' transition seal above the filter pack, and grouted to the surface with a cement based grout material. The wells will be finished with a locking pressure cap situated within a monument style (above ground) well vault. See the proposed Diagram of Well Construction (Plate 5). Note: The ' monitoring well screen length and slot size will be field assessed based on the lithologies encountered during advancement of the borings and adjusted to best suit the construction of the monitoring well. 1 Once the monitoring wells have been installed, the top of each well will be surveyed so that depth to groundwater measurements in the wells can be converted to groundwater elevations used to assess groundwater gradients. The wells will be surveyed relative to a local benchmark. If a local benchmark is not available near the site, the wells will be surveyed relative to an onsite, assumed benchmark with an assigned elevation. The wells will be surveyed as described in Appendix B ' Section B-3.4. 3.3 MONITORING WELL DEVELOPMENT A minimum of 48 hours after installation, the monitoring wells will be developed to remove fine ' silt from the well bore and to effectively increase the hydraulic radius of each monitoring well. Surging along the screened interval of the well will be performed to set the sand pack during installation and during the development stage. The monitoring wells will be developed as 12406/2002RI60 Page 6 of 13 Copyright.2002,Kleinfelder,Inc. February 20,2002 KLEINFELDER 2825 East Myrtle Street,Stockton,CA 95205-4794 (209)948-1345 (209)948-0621 tax