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Workplan: Groundwater Investigation Page 3 Proposed Cintra Park Phase II Development, Tract 2705 Tracy, California December 8, 1997 CTE Job No. 20-0445 the sampling port of the Gastech will be introduced in o the headspace above the soil sample. A sample of the headspace vapors will be withdrawn and analyzed for hydrocarbon vapors by the Gastech. Additionally, selected, soil samples will be submitted to State of California-certified environmental laboratory for analytical testing. Soil sample identifications,including boring designation and depth, will be recorded on a chain-of-custody form before deli-very to the laboratory. Soil samples delivered to the laboratory will be analyzed for total petroleum hydrocarbons (TPH) for gasoline fuel range (by EPA Method 8015-modified) and volatile aromati hydrocarbons (by EPA Method 8020). A groundwater monitoring well will be installed in each open borehole using new, two-inch diameter polyvinyl chloride (PVC) casing. The screen interval will extend from approximately 5 to 15 fbg. After construction, each well will be developed by mechanical surging, using a surge block to force water into and out of the screen to settle the sand pack W remove fines from the well. The wells will then be bailed to remove the suspended sediment and other contaminants. Following installation and development, each well will be left to settle and reach equilibrium for a minimum of 72 hours. At that time, the well will be nonitored for the presence of free floating petroleum product. If no free floating petroleum product is encountered then groundwater samples will be collected with new PVC bottom-full bailers. Appropriate guidelines will be followed during groundwater collection procedures. If groundwater samples are collected they shall be analyzed for TPH for gasoline fuel range (by EPA Method 8015-modified), volatile aromatic hydrocarbons (by EPA Method 8020), and, methyl-tert-butyl-ether(MTBE) and other oxygenates (by EPA Method 8260). Drilling equipment will be decontaminated by steam leaning before being used at the site. Also sampling equipment will be washed before being used and again between sampling events with a phosphate-free detergent solution, and double rinsed ith tap water and distilled water. Soil cuttings and purged groundwater will be temporari y stored at the site,in appropriately labeled DOT-approved drums pending receipt of laboratory analyses. A decision on where to send the drummed soil and groundwater will be made following receipt of the laboratory analyses. It is anticipated the drummed soil and groundwater will beremoved from the site within 30 days of the completion of field work. Documentation demonstrate ig that the appropriate disposal method has been used will be provided. A technical report documenting the findings of this invc stigation will be submitted to the PHS/EHD by January 30, 1998. Additionally, the groundwater monitoring well will be evaluated for the 11WORDICIPROJECTS12004451Workplan-GW well.doc