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Work Plan for Additional Subsurface Assessment and Remedial Action—Former Unocal Station#0187 <br /> November 27,2001 <br /> To implement this scope of work, GR proposes the following seven tasks: <br /> Task 1. Pre-field Activities <br /> GR will update the site-specific safety plan and obtain the necessary well installation permits from the <br /> SJCPHS and encroachment permits from the City of Stockton. Underground Service Alert (USA) will be <br /> notified at least 48 hours prior to initiating field work. A private line locator will be contracted to clear <br /> the proposed well boring locations. <br /> Task 2. Well Installation <br /> GR will install one groundwater monitoring well at the location shown near the southeast corner of <br /> American Street and East Miner Avenue on Figure 3. Drilling and well construction will be performed by <br /> a Califomia licensed driller. The groundwater monitoring well will be installed to a depth of <br /> approximately 120 feet bgs. Soil samples for description and possible chemical analysis will be obtained <br /> from the well boring at five-foot intervals, as a minimum. A GR geologist will monitor the drilling <br /> activities and prepare a log of the deepest boring only. Soil samples collected at 30 feet bgs,and every 10 <br /> feet in depth thereafter will be submitted for chemical analysis as described in Task 6. <br /> Soil from each sampled interval will be screened in the field for the presence of volatile organic <br /> compounds using a photoionization detector (PID). These data will be collected for reconnaissance <br /> purposes only, and will not be used as verification of the presence or absence of petroleum hydrocarbons. <br /> Screening data will be recorded on the boring logs. <br /> The groundwater monitoring well will be constructed with 2-inch diameter Schedule 40 polyvinyl <br /> chloride (PVC) well casing and 0.02-inch machine slotted well screen. The well will be screened from <br /> approximately 110 to 120 feet bgs. The actual screen interval will depend on the groundwater depth and <br /> lithologic conditions encountered during drilling. Proposed well construction details are presented in <br /> Figure 4. <br /> Drill cuttings will be stored at the site pending receipt of chemical analytical data for disposal. The drill <br /> cuttings will be stockpiled on and covered with plastic sheeting. Four discrete soil samples will be <br /> collected from the drill cuttings for disposal characterization as described in Appendix A. These samples <br /> will be submitted to the laboratory for compositing and analysis as described in Task 6. Stockpiled soil <br /> and steam cleaning rinsate will be transported for disposal at an appropriately licensed facility. <br /> Task 3. Well Development and Sampling <br /> The newly installed groundwater monitoring wells will be developed after being allowed to stand a <br /> minimum of 72 hours following completion. During development, the clarity of the discharged well <br /> water and selected groundwater parameters (pH, temperature, and conductivity) will be monitored. When <br /> the discharge water runs clear and the groundwater parameters have stabilized, a groundwater sample will <br /> be collected. Groundwater removed from the well during development and sampling will be transported <br /> to an appropriately licensed facility for disposal. The groundwater samples will be analyzed as described <br /> 240042.11 4 <br />