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ARCADIS to store chemicals are located along the northern and central areas of the Site. A few fruit or nut trees were observed in the southwestern portion of the Site. A cluster of a few 55-gallon drums with vegetation growing out of the tops was observed along the western site boundary. ARCADIS staff will perform soil sampling as specified in this Work Plan. ARCADIS will be responsible for obtaining required agency permits prior to initiating the subsurface investigation. California-certified laboratories will be selected for analysis of the soil samples. 3.2.1 Rationale The Site may have been used for agriculture purposes prior to development for residential use, and its most recent history shows that pesticides were potentially stored on and sold from the property. A small "orchard" of unknown nut trees is currently present in the southwestern section of the property; therefore, in order to assess potential impact from pesticide use in this area, shallow soil samples will be collected from this area. Mr. Larry Gordon serviced numerous vehicles on the property and there is a potential of used oil spillage. Evidence of motor oil staining was observed on shallow soil in the vicinity of soil boring B-6 as depicted on Figure 2. Oil-range hydrocarbons are relatively immobile and degrade relatively quickly in the environment. However, used motor oil may be laden with heavy metals that are not biodegradable. Metals, such as arsenic, are also a component of pesticides and industrial chemicals. Therefore, the proposed soil sampling plan is designed to investigate potential impact to shallow soil from pesticides and heavy metals. In addition, given the history of this Site, soil samples will also be collected from various points on the property (see Figure 2) and analyzed for volatile organic compounds (VOCs; see Table B). As part of the investigation, 79 soil samples will be collected from 48 locations. The borings are positioned within a 100-foot grid pattern across the Site (Figure 2). Soil samples collected from 0 to 0.5 foot will be analyzed as discussed in Section 3.5. Results will be compared to the Regional Screening Levels for residential soil (EPA 2009). If a reported analyte concentration exceeds these screening levels, the deeper sample from that location will be analyzed for that constituent. Additional sampling in a future investigation may also be recommended. Soil Sample B-39 is located beneath a power pole transformer, which may have historically contained polychlorinated biphenyls (PCBs). Therefore, the DTSC has requested that the soil sample from B-39 also be analyzed for PCBs. The ash found inside the silo, S-3, is being sampled because, in 2009, the silo was the scene of a fire believed to be started by suspected vagrants. Aluminum containers of an unknown substance were piled in the middle of the silo and set a fire resulting in the Page 16 wp-PEA-Gordon-Jul10-RV009808.doc: