ARCHIVED REPORTS_SOIL AND GROUNDWATER INVESTIGATION REPORT 2008

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' Soil and Groundwater Investigation Report Vernalis Offsite June 2008 ' Installation seven borings(SB-26, SB-27,SB-28, SB-29, SB-31, SB-32, and SB-33)from which groundwater samples would be collected for laboratory analysis of the CDCs. Access to the SJVHGA property has been difficult to obtain;therefore, borings SB-31 through SB-33 were proposed for location in the Highway 33 ROW. 3. SCOPE OF WORK ' SAIC implemented the work plan as described in sections 3.1 to 3.3. 3.1 PERMITTING,ACCESS,AND SITE SAFETY To maintain regulatory and legal compliance,protect the health of all involved persons, and prevent accidents, SAIC implemented the following: • Completed strategic planning and project setup activities, including the site-specific Health and Safety Plan, site-specific Journey Management Plan, and the clearance of subsurface utilities. • Determined the ownership of and obtained access to private properties coincident with the scope of work described herein. • Conducted a site visit to mark boring locations for Underground Service Alert(USA),notified USA at least 48 hours in advance of field activities,and requested USA to mark underground facilities in adjacent public ROWS. • Subcontracted Cruz Brothers, a private utility locator, to survey the site and proposed boring locations for any potential overhead and underground hazards and/or other potential obstacles. • Subcontracted Flash Safety to provide traffic control measures for borings advanced in the Highway 33 ROW. • Obtained soil boring permits from the San Joaquin County Environmental Health Department and Stanislaus County Department of Environmental Resources. • Obtained an encroachment permit from State of California Department of Transportation. ' 3.2 FIELD INVESTIGATION ACTIVITIES Seven borings (SB-26 through SB-33) were advanced to total depths ranging from 40 to 44 feet to define the lateral extent of affected soil and groundwater at the site. All groundwater samples were collected using temporary pre-packed well screens. The work plan indicated that up to three soil intervals at each boring location would be sampled: (1)the ' top 10 feet bgs for risk assessment, (2)below 10 feet bgs to assess the magnitude COCs in the most affected soil, and(3)beneath the affected zone to determine the vertical extent. However, affected soil was not observed in any boring and groundwater was encountered between 32 to 39 feet bgs; thus,work plan and CTA requirements were satisfied by sampling(1) one interval centered at approximately 5 feet bgs for risk assessment, and(2) one centered just above the top of the groundwater-bearing zone. Groundwater samples were collected from each boring and analyzed by the laboratory for the COCs. Additional groundwater samples were collected from borings SB-27 and SB-32 and analyzed for General Minerals to evaluate the potential of the uppermost groundwater for drinking. SPH and sheen were not observed in any boring or well. The investigation was implemented in accordance with the work plan with no exceptions. Refer to Appendix B for more information regarding the field, sampling, and analytical methods employed during the field investigation. 1 5 From Science to solutions