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• March 31,2005 Mr.M. Scott Mansholt—CEMC Site Investigation Workplan,Mountain House Sites#4 and#5 Page 3 of 5 OBJECTIVE AND SCOPE OF WORK ' The scope of work outlined below is being proposed to collect data required to delineate the lateral and vertical extent of petroleum-affected soil at the subject sites. At Mountain House Site ' 44, SAIC proposes advancing five primary and four contingency soil borings to delineate soil and groundwater in the vicinity of the residual petroleum identified beneath the site. At Mountain House Site#5, SAIC proposes advancing five primary and four contingency soil borings to delineate soil and groundwater in the vicinity of the residual petroleum identified beneath the site. The proposed soil borings locations for Mountain House Sites#4 and 45 are presented on Figures 3 and 4. Proposed boring objectives are presented in Table 1. ' PERMITTING AND ACCESS Prior to conducting field activities, SAIC will obtain soil boring permits from the San Joaquin County Public Health Services (SJCPHS). Access to advance any borings located in the Mountain House Community Services District(MHCSD) ROW will require an encroachment permit and traffic control. SAIC will prepare the traffic control plan and submit along with the encroachment permit application. If required, CEMC will post a performance bond for work ' conducted in the MHCSD ROW. The proposed borings are likely to be located on private property and will require an access agreement. CEMC will secure access to these properties prior to any fieldwork. A site-specific health and safety plan(HASP)will be prepared prior to any field activities. The HASP will include driving directions to the nearest hospital,a hospital route map, and job safety analysis of the work activities to be performed. The HASP will be kept on site, reviewed daily with all on-site personnel,and made available for review during investigation activities. While marking proposed boring locations, potential safety concerns and obstacles to the proposed scope of work will be observed and noted, such as overhead lines, marked and unmarked 1 underground lines, and pedestrians and automobile traffic. Underground Service Alert(USA) will be notified of all proposed boring locations at least 48 hours prior to any intrusive field activities. All USA ticket alerts will be confirmed and cleared prior to any intrusive field ' activities. In addition, SAIC will subcontract a private utility locator to clear the proposed boring locations for underground utilities. All fieldwork will be conducted in accordance with SAIC's standard operating procedures(SOPS). SOIL BORINGS Previous sampling and chemical test results summarized and presented in the Condor's Chevron Pipeline Easement Assessment Report(November 2001), identified petroleum-affected soil in ' borings GP-53 and GP-180 at Site#4,and borings GP-64 and GP-183 at Site#5 at depths ranging from 4 to 16 feet bgs. Maximum concentration of TPHc was 13,000 mg/kg. During Condor's investigation, groundwater was encountered beneath the site at depths ranging from 8 to 17 feet ' bgs. Grab groundwater samples were not collected during this investigation. Based upon the results presented in Condor's report,soil borings will be advanced to a proposed depth of 25 feet bgs. Geoprobe or hollow-stem, auger-type equipment will be used to advance ' the proposed soil borings. The borings will be continuously cored and field screened using PID equipment to detect the presence of residual petroleum in soil. The soil will be logged in general accordance with the Unified Soil Classification System as presented in ASTM 2488-90 and under the supervision of a California Registered Geologist. All down-hole equipment will be cleaned using a Liquinox/water solution to prevent the possibility of cross contamination between consecutive boring locations. The proposed boring objectives are presented in Table 1 and the proposed soil boring locations are shown on Figures 3 and 4.