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Additional Site Assessment Report 324 East 11 th Street Tracy,CA October 8,2014 Pangea retained Vapor Tech Services(VTS)of Hayward,California,to drill the borings.VTS conducted the associated soil and groundwater sampling using a Geoprobe 7822DT combination auger/direct push rig equipped with dual tube sampling equipment. Dual-tube direct-push drilling methods employ an outer tube to help avoid cross contamination within the inner sampling tube. This drilling method allows collection of continuously cored soil samples.All borings were first hand augered to approximately five feet below grade surface(bgs)to avoid damaging any unmarked subsurface utilities. Borings B-7S, B-9,and B-10 were advanced to approximately 20 ft bgs,and boring B-71)was advanced to approximately 24 ft bgs. Boring B-71) was originally named boring B-7, but the "D" suffix was added to denote the deeper (21 to 24 ft bgs) water sample collected at this location. Boring B-7S was located approximately 3 ft west of boring B-71)to collect a shallow(15 to 20 ft bgs)water sample. Boring B-8 was advanced to approximately 5.5 ft bgs to help further delineate shallow soil contamination. Select soil and water samples were collected from each boring in accordance with Pangea's Standard Field Procedures for Soil Borings (Appendix B). Soil samples were collected for laboratory analysis in acetate liners, and capped with Teflon tape and plastic end caps. Soil samples were collected at approximately 4 ft intervals. To sample first-encountered groundwater in borings B-7S, B-9, and B-10, the inner drilling rods were removed,temporary PVC piping and well screen was installed within the boring,and the outer drill rods were then removed. To sample deeper groundwater in boring B-71),the outer casing was pulled back from approximately 24 ft bgs to 21 ft bgs to expose 3 ft of screen.Grab groundwater samples were collected in new disposable bailers and were then decanted into the appropriate laboratory supplied containers. Boring logs are included in Appendix C. All samples were shipped under chain of custody to McCampbell Analytical,Inc.,of Pittsburg,California,a California-certified laboratory. The drilling was observed in the field by Pangea project scientist Morgan Gillies and supervised by Bob Clark- Riddell,a California Registered Professional Civil Engineer(P.E.).Soil characteristics such as color,texture, and relative water content were noted in the field using the USCS classification system and entered onto a field boring log.Field screening of soil samples for potential hydrocarbons and volatile organic compounds included visual and olfactory observations. 3