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Workplan for Additional Assessment and Subslab Gas Sampling Tracy Office Plaza 324 E. 1 Ith Street, Tracy,CA November 22, 2013 • Pre-mark the boring locations with white paint, notify Underground Service Alert (USA) of the drilling and sampling activities at least 72 hours before work begins,and conduct private line locating as merited; • Prepare a site-specific health and safety plan to educate personnel and minimize their exposure to potential hazards related to site activities;and • Coordinate with drilling and laboratory subcontractors and other involved parties. AP Task 2—Soil Borings To provide additional assessment near the potential former piping location,Pangea proposes to advance two borings (B-7 and B-8), as shown on Figured. Additionally, Pangea will install one boring(B-9)northwest (downgradient)of former boring B-1, within the planter along E 1 Ith Street. If significant contamination is observed in soil or groundwater from boring B-9,a contingent step-out boring(B-10)will be installed within the sidewalk planter on the north side of E. 11 th Street.At each boring location,soil samples will be collected every four feet and a grab groundwater sample will be collected from first-encountered groundwater. For borings near the identified piping(presumably from the former service station),samples will also be collected about 1 of 2 ft bgs,and near field indications of hydrocarbons.To provide additional vertical delineation near the potential source area,Pangea will install one boring(B-7)to approximately 25 to 30 ft bgs using dual-tube equipment to obtain a representative sample from deeper groundwater.To help avoid cross-contamination from shallower soil,the outer rod will remain in place and retracted to expose the screened section at the bottom of a temporary PVC casing that will be installed within the outer rod. Pangea will conduct site investigation using a direct-push sampling rig.The direct-push sampling rig will be equipped with a hydraulic hammer and steel drive rods to advance the borings to total depth.With hydraulic- push drilling,continuous soil collection is conducted using acetate liners and samples are typically collected on four foot intervals.Soil samples will be obtained by cutting 6-inch subsections,trimming the excess soil from the ends,and capping the ends with Teflon®tape and plastic caps.Additional soil samples may be collected near the water table and at lithologic changes.The soil samples will be classified according to the Unified Soil Classification System(USCS)and screened for field indications of petroleum hydrocarbons using visual and olfactory observations and a photo-ionization device(PID). All site investigation activities will be performed under the supervision of a California Registered Civil Professional Engineer (P.E.). Additional soil and assessment procedures are presented in our Standard Operating Procedures(SOPS) in Appendix C. 3