SITE INFORMATION AND CORRESPONDENCE

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Phase 3—The attached figure of the area northeast of the DDJC-Tracy Annex shows the proposed groundwater sample locations(P-8 to P-10,P-11 to P-12, and P-13,respectively)on the McClellan, Graham, and Union Pacific Railroad properties.Groundwater samples will be collected from CPT borings in both the Upper Horizon and Middle Horizon at each boring location; samples will be analyzed by an on-site laboratory. The site map also includes the locations of existing wells,CPT borings and the four proposed monitoring wells(LM 150 through LM 153)on the Robertson property (two of the proposed Robertson CPT borings will only be completed if proposed monitoring wells LM150 to LM 153 are not installed and sampled within 30 days of the CPT sampling).Additional CPT locations(step outs from the initial locations)will be completed where groundwater results from the on-site field laboratory show TCE contamination exceeding 5 pg/L(MCL). Step-out locations will be at 800-foot distances from the initial location(north, south,east, and west),until TCE is below 5 µg/L.Groundwater samples from step-out locations will be analyzed using the same field laboratory as will be used on the initial locations (using U.S.EPA Method SW 8260 analysis of groundwater samples). Before any CPT groundwater sampling is initiated, the required permits will be obtained from the San Joaquin County Environmental Health Division,as well as clearance of all of the locations of above and below ground utility hazards near each CPT location.Right-of-entry permits for the proposed CPT activities on the McClellan, Graham,Robertson, and Union Pacific Railroad properties will be obtained by CESPK-RE. Proposed Groundwater Sampling Activities Groundwater samples will be collected in the Upper Horizon and Middle Horizon at each of the 13 proposed CPT locations(see site map; includes McClellan,Graham,and Union Pacific Railroad property locations).Exact depths of sample collections will be determined from interpreted CPT lithology after each CPT boring is hydraulically advanced to total depth.A detailed description of the CPT field methodology can be found in the Comprehensive Field Work Plan.A cement grout will be used to fill the holes produced by the CPT borings following groundwater sampling efforts. Guidelines used for the installation of the grout are also presented in the Comprehensive Field Work Plan. Groundwater samples will be analyzed for TCE using U.S.EPA Method SW8260.The sampling of private wells and the CPT investigation along Bird and Lovely Roads will use an off-site laboratory; CPT on private properties will use an on-site laboratory to allow for step-out decision making. Analytical requirements are documented in the DDJC-SharpetPracy Comprehensive Field Work Plan/Quality Assurance Project Plan. Analytical results will be incorporated into the DDJC- Sharpe/Tracy Environmental Database Management System(EDMS). Following completion of the CPT groundwater sampling effort, the ground surface elevations will be measured for each of the CPT locations.Horizontal coordinates will be determined to the nearest 1.0 foot and referenced to the State Plane Coordinate system,Zone 3,North American Datum of 1983, and ground surface elevations will be determined to the nearest 0.1 foot.These elevations will be referenced to the National Geodetic Vertical Datum of 1988. Survey data will be incorporated into the DDJC-Sharpe/Tracy Environmental Management System(EDMS)database. Logistical Considerations As shown on the attached site map, vehicle access routes to and from the proposed CPT locations will be followed as indicated by the arrows.The amount of soil disturbance is expected to be minimal, unless surface soils are very wet.The CPT effort on private properties is not expected to occur until 3