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Chevron Environmental Management Company Soil and Groundwater Investigation Report Tracy Byron Road Project SAIC contacted Underground Service Alert(USA)to notify utility providers within the area of the drilling investigation. As an additional precaution, SAIC contracted Cruz Brothers Locators of Scotts Valley, California to provide a supplemental underground utility identification due to the proximity of the proposed borings to several known underground utilities in the City of Tracy ROW. Due to multiple known utilities located in the southern shoulder of Byron Road and as an additional precaution prior drilling, Cruz Brothers cleared the upper 5 feet of borehole using an air knife. However, due to subsurface conditions, SAIC determined that the air-knife procedure was not time efficient and requested Cruz Brothers to continue the borehole clearances by hand auger. A total of 10 soil borings were cleared by air knife. 4.3 SOIL BORINGS—COLLECTION OF SOIL AND WATER SAMPLES In order to evaluate the extent of residual petroleum affecting soil or groundwater adj acent to the areas identified in the Workplan, SAIC supervised the installation of 36 soil borings (SB-1 through SB-36) in the City of Tracy ROW between October 20 and 30, 2003. An SAIC field geologist observed Gregg Drilling and Testing, Inc., of Martinez, California(C57#485165) advance the soil borings to depths ranging from 24 to 41 feet bgs using direct-push technology. Prior to advancing the soil borings, each soil boring was hand cleared to a minimum depth of 5 feet bgs by either air knife or hand auger. Soil borings SB-1 through SB-36 were continuously cored from 5 feet bgs to the total depth explored using a 4-foot Macrocore sampling barrel lined with a clear poly-acrylic liner. The Macrocore barrel was advanced directly into the soil boring and, upon retrieval,the poly-acrylic liner was removed from the Macrocore barrel and the soil core was inspected and logged according to the Unified Soil Classification System(USCS) in accordance with American Society for Testing and Materials (ASTM)D 2488 standards. The soil core was field screened for the presence of organic vapors using a photoionization detector(PID) and recorded on the boring logs. Soil samples were collected from the poly-acrylic liner by trimming the desired interval and sealing each end with Teflon sheets and plastic end caps. The samples were immediately labeled and placed in an ice-cooled chest pending analysis. Soil encountered in the borings consisted of mixtures of clay, silt, sand, and gravel. Depth to first encountered groundwater during the October 2003 investigation was observed between 12 and 13 feet bgs. Soil boring logs containing PID readings,USCS descriptions, and other pertinent drilling data are included in Appendix C. All down-hole boring equipment was decontaminated between borings using a Liquinox solution and rinsed using potable water. Upon completion, all soil borings were abandoned by backfilling with cement grout to ground surface in accordance with SJCEHD procedures. Mr. Mike Infurna of SJCEHD was contacted prior to abandonment and permission to proceed with boring abandonment was granted on October 20, 2003. Soil boring locations are presented on Figures 2a and 2b. 4.3.1 Soil Sampling Soil borings were advanced to a target depth of 24 feet bgs unless residual petroleum-affected soil was encountered at the target depth. In accordance with the Continuous Technical Approach(CTA)Second Draft Revised Technical Approach to Site Evaluation and Decision-Making(Geomatrix Consultants, Inc., 2002)1 if petroleum-affected soil was encountered at 24 feet bgs the soil boring was advanced through the affected interval and terminated once several feet of non-affected soil was identified. Typically, soil samples were submitted from each boring from the following intervals: above first encountered groundwater or from the most petroleum-affected soil interval above first encountered groundwater based on visual and PID readings, and from the bottom of the boring. When possible, a soil sample was collected from a depth of less than 10 feet bgs for future health risk assessment purposes. SAIC collected 100 soil samples from 36 soil borings for laboratory analysis. In several cases during an attempt to collect soil from the 20-to 24-foot interval,no soil was recovered in the Macrocore sampler. If this occurred in a soil boring deemed non-affected(based on visual observations and PID readings), a soil sample was submitted from the bottom of the 16-to 20-foot bgs 4