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Work Plan for Groundwater Investigation and <br />Groundwater Monitoring Well Installation <br />Field Maintenance Shop #24, Stockton, California <br />purposes of establishing appropriate intervals for well screening, as described above, and for <br />preparing boring logs for incorporation into the investigation report. Soil samples for inorganic <br />laboratory analysis consistent with the methodologies described below will be collected in sterile <br />8 -ounce glass containers (or stainless steel/brass sleeves, covered with Teflon tape and sealed <br />with PVC caps). Pre -packed 25 -gram En -Core® samplers, or similar, will be used to collect <br />samples for TPH and VOCs analyses. All samples will be submitted to a California -certified <br />laboratory under chain -of -custody (COC) documentation to be analyzed for: <br />TPH-d using USEPA Method 8015 -Modified; <br />VOCs including TPH-g, Naphthalene, BTEX, and Fuel Oxygenates using USEPA <br />Method 82606; and <br />Total Lead using USEPA Method 6010B. <br />Soil samples will be labeled with a unique sample designation identifying the location and depth, <br />in that order (e.g., FMS-MW4-5'). Sample designations, collection times, and analysis <br />information will be recorded in the field notebook and on the COC form(s). <br />3.5 WELL DEVELOPMENT <br />A minimum of 48 hours after installation, to allow sufficient time for well materials to cure, the <br />wells will be developed by surging and swabbing using a surge block. Development water will <br />be pumped out of the wells into waste containers. The purpose of developing new monitoring <br />wells is to remove the residual materials remaining in the well after installation has been <br />completed. Development procedures will be continued until water removed from the well is <br />clear and free of any visible sediment, and the physical parameters of temperature, pH, and <br />conductivity have stabilized. Development water will be containerized and stored onsite until <br />properly characterized, along with other waste water generated during the investigation, and <br />transported offsite for disposal. <br />3.6 SPECIFIC CAPACITY TESTING <br />Following well development, specific capacity testing will be performed on two wells located <br />within the primary source area for petroleum hydrocarbons and related constituents as depicted <br />on Figure 4, and two wells outside the primary source area. The wells to be used for this testing <br />will be determined after evaluating lithologic data from the MIP investigation, coupled with <br />existing historical data for wells previously installed at the site, in order to identify the most <br />appropriate wells for this evaluation. Prior to pumping, pressure transducers with data logging <br />capability will be installed in each well selected for testing. Based on the results of well <br />development and pilot testing at the site in May 2012, we anticipate that each selected well will <br />be pumped for a period of no more than 4-6 hours, which should be sufficient to achieve <br />equilibration of drawdown. Following pumping, water levels will be monitored and logged for a <br />period of approximately 12 hours. Results will be used to estimate the transmissivity and <br />hydraulic conductivity of the aquifer in support of evaluating potential remedial alternatives <br />based on previous and upcoming treatability studies. <br />Water will be pumped at a constant rate from the selected wells for a specific time interval once <br />drawdown has equilibrated. The transmissivity will be calculated from the specific capacity <br />(equal to the pumping rate divided by the drawdown) by multiplying the specific capacity by <br />1500 for unconfined conditions, or 2000 for confined conditions (Driscoll, 1986), as appropriate <br />13 <br />OTI E <br />