ARCHIVED REPORTS_SOIL AND GROUNDWATER INVESTIGATION WORK PLAN

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' Soil and Groundwater Investigation Work Plan Vernalis Offsite April 2007 ' groundwater samples will be collected for laboratory analysis. SAIC will also collect shallow soil samples for use in a risk assessment. ' 3.1 PERMITTING,ACCESS,AND SITE SAFETY Before initiating the investigation in the field, SAIC will conduct the following: ' • Obtain boring permits from the San Joaquin County Environmental Health Department (SJCEHD) and the Stanislaus County Department of Environmental Resources(SCDER). • Update the site-specific Health and Safety Plan. ' • Update the site-specific Journey Management Plan. • Conduct a site visit to mark boring locations for Underground Service Alert, which will locate ' underground facilities in adjacent public ROW. • Subcontract Cruz Brothers Locators,a private utility locator, to identify any potential overhead and underground hazards. ' 3.2 DEPARTMENT OF WATER RESOURCES (DWR)FILE REVIEW Because DWR files were searched previously, a new search is not necessary. Water supply wells are ' indicated on Figure 1. A summary of the water supply well search results is presented in Table 1. 3.3 FIELD INVESTIGATION ACTIVITIES ' SAIC will contract a California-licensed(C-57)driller to operate truck-mounted,GeoProbe®direct-push equipment to advance seven borings to total depths up to 40 feet bgs on the Bogetti property and in the Highway 33 ROW(Figure 3). The GeoProbe®Dual Tube sampling system will be used to enable the ' low-flow sampling of groundwater,utilizing a pre-packed well screen. Prior to direct-push advancement, each boring will be hand cleared to 8 feet bgs. More details regarding the proposed boring program are provided in Table 2. ' Collection of Soil Samples Soil borings will be continuously cored using a GeoProbe®Dual Tube sampling system. The sampler will contain a plastic acetate liner that retains a relatively undisturbed soil core. The soil samples selected ' for analysis will be cut from the plastic liners, sealed with Teflon tape and plastic end caps, labeled with identifying information,and stored in a pre-chilled ice-chest for transportation to the laboratory. Each borehole will be logged for lithological content using the Unified Soil Classification System as a ' guide including color,relative moisture content, and other observable distinguishing characteristics(i.e., color changes, debris,rootlets,or odor). SAIC will utilize a photo-ionization detector(PID) to screen soil for the presence of volatile organic compounds. Lithologic observations,PID screening results,and other observations will be recorded on field logs. If affected soil is not present in a boring, then soil samples will be collected at a depth where affected soil was observed in adjacent borings. If no affected soil has been observed in adjacent borings, then soil ' samples will be collected just above the groundwater table. At each boring location,risk assessment samples will be collected from either the most affected soil ' within the 0 to 10 feet bgs interval,or from a depth of 5 feet bgs if no hydrocarbon is observed. Further, if the most affected soil is encountered below 10 feet bgs, then three intervals will be sampled: (1)the top 10 feet bgs for risk assessment purposes, (2)the most affected interval below 10 feet bgs for delineation purposes; and(3)beneath the zone of affected soil,to determine the extent and thickness of affected soil. ' However, if the most affected soil occurs in the upper 10 feet bgs, then samples from the top 10 feet bgs may concomitantly represent the most-affected interval and the shallow. risk-assessment interval. 1 5 =_ _= ' A=WfA#W'%i1`q From Science to Solutions