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Ms.Patricia Vellines 8188.001.002 The Trails of Manteca October 25, 2012 WORKPLAN FOR SOIL AND GROUNDWATER ASSESSMENT Page 3 • At the three borings proposed along the edge of the excavation footprint, soil samples will be collected at depths of 5 and 15 feet. These depths may be adjusted based on PID readings. Six soil samples will be submitted for analysis of TPHg and VOCs by EPA Test Method 8260B; TPHd and TPHmo by EPA Test Method 801513; and silica gel by EPA Test Method 3630. • At the six step out borings, surface samples will be collected at three of the locations and at two locations samples will be collected at 5 feet bgs. These five samples will be submitted to a State certified laboratory for analysis of PCBs by EPA Test Method 8082. Based on PID readings, four additional samples will be collected from these step out borings and submitted for analysis of TPHg and VOCs by EPA Test Method 826013; TPHd and TPHmo by EPA Test Method 801513; and silica gel by EPA Test Method 3630. GROUNDWATER SAMPLING Grab groundwater samples will be collected from all ten boring locations (Figure 2). Based on previous subsurface activities, groundwater in the vicinity ranges from approximately 11 to 18 feet bgs. Grab groundwater sampling will be performed after soil sampling has been completed to a depth of 25 feet at each location. Temporary PVC casing with a screened section from 15 to 25 feet will be inserted in each borehole for the collection of grab groundwater samples using new disposable bailers. Sampling equipment will be washed and triple-rinsed between sample collection to prevent cross-contamination of samples. Following collection, the PVC will be removed and backfilled in accordance to typical stand of care practices including backfilling with grout material. The water samples will be placed in laboratory-provided preserved or unpreserved glassware, as appropriate for the specific target analytes. Samples will be decanted into the appropriate glassware for the specific analysis. During decanting, care will be taken to eliminate headspace within the glassware (for VOC fractions) to minimize the potential for volatilization. Upon collection of samples, a sample label will be placed on the sample and include a unique sample number, sample location, time/date collected, laboratory analysis, and the sampler's identification. The ten-groundwater samples will be submitted for analysis TPHg and VOCs by EPA Test Method 826013; TPHd and TPHmo by EPA Test Method 801513; and silica gel by EPA Test Method 3630. Additionally, five of the groundwater samples will be submitted for analysis of PCBs by EPA Test Method 8082. SUPPLY WELL SURVEY We will perform a visual reconnaissance of the homestead area to identify potential supply wells. If any supply well(s) are identified, we will collect a groundwater sample from the supply well located closest to the AST area, if the well is active and/or readily accessible. The groundwater sample will be submitted for analysis of TPHg and VOCs by EPA Test Method 826013; TPHd and TPHmo by EPA Test Method 801513; silica gel by EPA Test Method 3630, and PCBs by EPA Test Method 8082.