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Privileged and Confidential, Attorney Work Product June 22,2018 Scope of Work for 455 E.Eleventh Street,Tracy,CA 95376 February of 1994, San Joaquin County Environmental Health Department determined that no further action was required.The UST is considered an HREC. The 2017 AGE Phase I ESA recommended the collection of soil samples to assess impacts from the RECs identified at the Site.Terraphase also recommends the collection and analysis of soil-gas samples to assess volatile organic compound (VOC) impacts to the Site from the RECs and the historic UST. Terraphase also recommends the collection and analysis of one groundwater sample to assess potential impacts to groundwater beneath the Site from the RECs and HREC. Lastly,Terraphase recommends the collection of soil samples to assess the subsurface soil for the presence of organochlorine pesticides from former use of the Site for agriculture. Scope of Work The scope of work to complete the objectives of the Investigation includes the following three tasks: Task 1- Drilling,Sampling,and Laboratory Analysis Task 1-Drilling,Sampling,and Laboratory Analysis The drilling and sampling program will include: 1. Three soil samples will be collected from the approximate center of the former UST location at 4.5-5, 8.5-9,and 12.5-13 feet below ground surface (bgs). 2. Two soil-gas samples will be collected in the immediate vicinity of the former UST at depths of approximately 5 and 10 feet bgs. 3. Three grab-groundwater sample will be collected as described in Task 1.3 below. The proposed additional sample locations are shown on Figure 1.The sample collection and analytical methods are described below and are organized by media to be sampled. Sub-surface sampling borings will be backfilled with cement in accordance with SJCEHD requirements. Pavement,gravel, or soil surfaces will be repaired using concrete,gravel, or soil to match original conditions as closely as possible. Spray paint used for utility clearance may remain visible for approximately one to two months. Investigation derived waste (IDW)will consist of soil boring cores, disposable sampling supplies, and decontamination rinse water.These materials will be placed into 55-gallon drum(s) and left at the Site until waste characterization and off-site disposal can be scheduled. IDW will be sampled, if necessary,to facilitate waste disposal acceptance. Task 1.1 Soil Sampling One boring will be advanced in the approximate center of the former UST location (identified as SB6 on Figure 1).The boring will extend to a depth of 20 feet bgs and will be used to collect soil samples, as well as a grab groundwater sample (discussed in Task 1.3). Samples will be collected at depths of 4.5 to 5 feet bgs and 8.5 to 9 feet bgs to assess the material used as backfill for the UST excavation when the tank was removed in 1989.The samples collected from these depths will be analyzed for OCPs,VOCs, CAM 17 metals,TPH-g,TPH-d,TPH-mo,SVOCs, and asbestos in accordance with DTSC's Guidance on Imported Fill Material (DTSC 2001). An additional soil sample will be collected from the boring at a depth Page 2 of 3 Terraphase Engineering Inc.