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09/12/97 16:43 GR/GSI—SACTO + 12094640138 P09 Work Plwt Pot Soil Boring and Monitoring Well Insial14Gn - Unwin Station No. 6981 September 12, 1997 To implement this proposed scope of work, GSI proposes the following five tasks. GSI Field Methods and Procedures are included in Appendix A. Task 1. Soil Boring and Well Ltstallatlon Task 1.1. Pre-field Activities GSI will prepare a site safety plan and obtain the necessary soil boring and monitoring well installation permits from the SJCEHD- An encmachment permit will be obtained from the City of Stockton for the offsite well. Underground Service Alert (USA) will be notified 48 hours in advance of the scheduled work. Prior to drilling, GSI will contract with a subsurface utility locator to clear the onsite boring location. Task 1.2, Well Installation and Soil Boring GSI will im itall one off-site groundwater monitoring well on the east side of pacific Avenue between the former locations of wells MW 12 and MW-13, and will drill one exploratory soil boring adjacent to the location of vapor extraction well VW 2. Proposed locations are shown on the Figure 2. Drilling will be performed by Woodward Drilling (C57 #710079). A GSI geologist will monitor the drilling activities and prepare a log of each boring. Soil borings will be drilled with 8-inch diameter hollow-stem augers. The well boring will be drilled to approximately 55 feet bgs., and the exploratory soil boring will be drilled to approximate) 40 feet bg Upon completion, the o.1 boring will be backfilled from approxima 40 to 33 feet bgs wi OI2C shirr d from 33 fee[ to ground surface with neat cement using a tremie pipe and pump. Soil samples for description and possible chemical analysis will be obtained from each boring at five-fiwt intervals, as a minimum, Soil from each sampled interval will be screened in the field for the presence of volatile organic compounds using a ,plotoionizationdetector(PID). Screening data will be recorded on the boring logs. Although the actual number of samples submitted for chemical analysis will depend on site conditions and field screening data, we anticipate a minimum of three soil samples collected from above groundwater will be submitted for chemical analysis as described in Task 5. The groundwater monitoring well will be constructed using 2-inch diameter Schedule 40 polyvinyl chloride (PVC) well casing and 0.02-inch itlachine-slotted well screen. The wells will be constructed With 30 fret of screen (25 to 55 feet bgs). The annular 7ass.zra 4