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APPENDIX A: SUMMARY OF PREVIOUS ENVIRONMENTAL ACTIVITIES SOIL AND GROUNDWATER INVESTIGATION REPORT'. ' SAIC Energy, Environment& Infrastructure, LLC (SAIL) supervised the advancement of 36 soil borings (SB-1 through SB-36)in the City of Tracy right of way(ROW)between October 20 and 30, 2003,to evaluate the extent of residual hydrocarbons affecting soil or groundwater adjacent ' to the areas identified in the 2003 Tracy Byron Road work plan. The soil boring depths ranged from 24 to 41 feet below, ground surface(bgs). Soil encountered in the borings consisted of mixtures of clay, silt, sand,and gravel. Depth to first-encountered groundwater was between 12 and 13 feet bgs. SAIC collected soil and grab groundwater samples from selected boring ' locations for analysis of the constituents. The data collected during this and past site investigations indicated that residual crude oil has affected soil at various depths to approximately 30 feet bgs, and that the majority of the affected soil is located between 4 and 20 feet bgs. Groundwater was also affected at several locations along Byron Road. 1 SAIC concluded the following based on review of the investigation data: • Soil and groundwater near borings SB-2, SB-3, and SB-6 were not fully characterized and the lateral extent of these affected media was not known. Further investigation near these borings was deemed necessary. • Soil and groundwater near borings SB-8 through SB-12 were not fully characterized and the lateral extent of these affected media was not known, and therefore required further assessment. • Soil and groundwater appeared to be delineated in the area of borings SB-13 through SB-16;therefore, additional investigation was not necessary. • Affected soil and groundwater in the vicinity of borings SB-19, SB-22 through SB-26, and SB-36 were not fully delineated and the lateral extent of residual hydrocarbons was unknown; therefore,further assessment was required. • Affected soil and groundwater were present near borings SB-28, SB-30, and SB-33 through SB-35. Additional assessment was warranted near these borings. SAIC recommended advancement of additional step-out borings in the above-referenced areas to fully delineate affected soil and groundwater south of West Byron Road. SAIC recommended that soil and grab groundwater samples be collected from the step-out borings and tested by a laboratory for the constituents. ' The Central Valley Regional Water Quality Control Board (RWQCB)reviewed the data presented in the 2004 soil and groundwater investigation report, concurred with SAIC's recommendations for additional step-out borings, and suggested the following boring location': ' 1. SAIC,2004. Soil and Groundwater Investigation Report at, Tran,Byron Road Project,Tracy California.February_ 2. Central Valley RWQCB.2004_ Review of Soil and Groundwater Investigation Report-Byron Road Project,west Byron Road,Tracy,San Joaquin County_ April 19. A-1 SAIC 1