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_ r e LEEOSNIL.........—gr a INC. ,...._- The two monitoring wells will be approximately 60 feet deep and designed to monitor water levels and water quality in the upper water bearing zone. The wells will be constructed with 4 -inch diameter, Schedule 40 PVC well casing with flush joint threads. Ten continuous feet of 0.010 inch slotted screen (#10) will be installed in each well . The screens will be attempted to be set so that they extend both above and below the depth at which water is first encountered during drilling. However, it may not be possible to install these screens higher than a depth of fifty feet due to the Public Health Services, San Joaquin County, restrictions regarding a minimum 50- foot sanitary seal. No glue or solvent will be used in the construction of these wells. The annulus of the well will be sand packed to above the perforated zone using an engineered sand pack, and then sealed with a bentonite pellet cap prior to placement of the anticipated 50-foot cement grout sanitary seal to the surface. Each monitoring well will be contained within a flush-mounted enclosure with a locking cover. Locations and measuring point reference elevations (to 0.01 feet) for each well will be determined by a licensed surveyor. A typical monitoring well design is presented on Figure 2. The wells will be drilled using hollow stem augering equipment, by a Cali- fornia licensed C-57 water well contractor who is experienced in monitoring well installations. Drilling will be conducted without the use of lubrica- tion on the drilling equipment. All drilling equipment and casing materials will be high pressure steam cleaned prior to initiating drilling operations at each of the monitoring well sites. All drilling will be done under the supervision of a professional engineer or geologist. A detailed boring log will be prepared, noting soil types (Unified Soil Classification System), moisture conditions, and drilling penetration rates. All monitoring wells will be constructed and developed to provide discrete, ng wells will be developed using a representative samples. Monitori combination of air development, and/or surge block/bailing, as directed by the on-site engineer. Due to the suspected volatile compounds being investigated, extreme care will be exercised during the collection of these samples to ensure representativeness. EPA and California Lepartment of Health Services protocol will be followed by field personnel during the collection, preservation, and transport of collected samples. Water quality sampling stabilization records and chain-of-custody forms will -. - ---- - --- -- --.---- accompany-each--set—of-samples. -- 9