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EPA Method 8015M; Title 22 Metals using EPA Method 6010/7000 series; and VOCs using EPA Method 5035/8260. A COC form was completed and shipped with the sample cooler to Calscience Environmental Laboratories, a state of California certified laboratory. • Monitoring Well TW-5 Construction - Monitoring Well TW-5 was constructed using 4-inch diameter Schedule 40 PVC well casing. The well was screened from 5.75 to 25.75 feet bgs with 0.010-inch slotted PVC casing that was capped at the bottom with a solid 4- inch diameter end cap. The well was completed to surface grade with 5 feet of blank Schedule 40 PVC. The filter pack for the well consists of Lonestar #2/12 sand from 26 feet bgs to 3 feet bgs. The remainder of the annulus was backfilled with bentonite chips to seal the well. At the surface, the well was protected with a flush mounted Emco Wheaton traffic rated well box, which was cemented in the ground to prevent damage to the well. In addition, the bentonite seal was brought up inside the skirt of the well box to prevent the borehole from becoming a conduit to groundwater. Finally, the well was secured with an expandable cap that can be locked to prevent tampering with the well. The locations of the wells in the network at the Site are provided in Figure 9. Well completion diagrams are provided in Appendix E. • Monitoring Well Development - Five monitoring wells were developed using a combination of surge, bail and pumping techniques. Development consisted of using a surge block to force the filter pack around the screened interval to settle and to draw fines through the filter pack into the well. Thereafter, a bottom sampling bailer was used to remove the solids from the bottom of the well. After the bailing had removed a majority of the solids, an electronic submersible pump was placed in the well to complete the development. The pump was then used to draw the turbid water out of the well. Development was considered complete when the following was achieved: 1) a minimum of 5 borehole volumes of water had been removed from the well; 2) groundwater parameters, including temperature, conductivity, pH and turbidity had stabilized to within 10% between consecutive readings measured approximately 1 minute apart; and 3) when the turbidity of the groundwater was 10 nephelometric turbidity units or less. Water generated during development activities was stored in 55-gallon drums and was transported and disposed/recycled to the Waste Management Kettleman Hills Facility, a PG&E approved facility after receipt of the analytical results from the laboratory. The monitoring wells were developed to improve their hydraulic connection with groundwater so as to obtain representative water samples and water levels. Development was completed a minimum of 72 hours after well construction was completed. The wells were developed before sampling and depth to groundwater were collected to determine the hydraulic gradient. Well development logs are provided in Appendix H. • Monitoring Well Sampling - The five groundwater monitoring wells in the on-site well network were sampled. Sampling operations were initiated more than 7 days after the development of TW-5 as required by State of California Standards. Groundwater sample logs are provided in Appendix I1 and the discussion of the groundwater sampling procedures are provided in the following section. Prior to the collection of groundwater samples, monitoring wells TW-1 and TW-2 were video logged to see if these wells were viable for use in the monitoring well network at the Site. Results from the video logging are provided in Appendix J. PARSONS 25 FINAL RI REPORT-FORMER TRACY MGP APRIL 2010