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WORK PLAN FOR ADDITIONAL SITE ASSESSMENT FORMER SHELL STATION 2575 Country Club Boulevard, Stockton, CA The LTCP screening number for benzene in soil samples collected between 0 and 5 feet below ground surface (ft bgs) was exceed by one soil sample, PE8-1.5, collected in 1995. All other soil samples collected between 0 and 5 ft bgs were either excavated or were below the LTCP screening numbers. By 10 March 2017, please submit an argument that the Site meets LTCP low risk criteria for dermal contact, or submit a scope of work for additional soil sampling from the location of Sample PE8-1.5 to confirm current Site conditions in the area of that sample. This discussion or scope of work should be included in the Work Plan requested in item 4 below. Sample PE-8 is the only soil sample obtained from a depth of less than 5-feet that has a benzene concentration exceeding the LTCP guidelines for residential and commercial Site use scenarios. Sample PE-8 was collected from a product line excavation in early 1995. Since that time, several samples have been obtained from depths of approximately 5-feet or less in the general area of PE-8 (P-5-4.0, P-6-5.5, P-7-5.0 and P-8-5.0). The locations of these samples relative to sample PE-8 are shown on Figure 3. Benzene was not detected in any of these samples above its method detection limit of 0.0050 mg/Kg (Cambria 2005). A summary of historical soil analyses is provided as Table 1. Based on these data, and affinity of aerobic degradation of benzene in shallow soils, we do not believe that further sampling in the vicinity of PE-8 is warranted, and respectively request that this requirement be removed. 3.4 Analyses of Waste Oil UST Soil Samples - Item #4 4. Soil samples .from the waste oil tank excavation were not analyzed .for polycyclic aromatic hydrocarbons (PAHs). Analysis for PAHs is required prior to consideration .for case closure. Therefore, by 10 March 2017, submit a work plan for collection of at least two (2) soil samples from native soil beneath the former waste oil tank excavation. A soil boring will be advanced to a depth of 12 feet below ground surface (bgs) at the location shown on Figure 2. Boring and sampling procedures are described below. 3.4.1 Pre-Field Activities Pre-field activities included the following: Preparing a Site-specific Health and Safety Plan (HSP). Notifying Underground Service Alert (USA) and performing an underground utility clearance for the planned drilling location; and Obtaining any necessary permits. 3.4.2 Drilling and Soil Sampling One boring will be advanced in the approximate center of the former UST location. The proposed location will be marked on the surface in while paint. Underground Services Alert will be notified of Page 4