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r Stantec PEA WORKPLAN Proposed Lodi Energy Center Site Lodi, California 4.0 PAST SAMPLING ACTIVITIES Past sampling activities at the Site included collection and analysis of shallow soil samples. In addition, one groundwater monitoring well (WSM-3) is present on the Site, and has been sampled for water quality parameters. The results of these soil and groundwater analytical data are presented below. Sampling of other media including surface water, sediment, or soil vapor have not been sampled. 4.1 SOIL DATA Prior soil sampling on the Site was documented in a memorandum entitled NCPA Lodi Preliminary Phase 11 ESA Sample Results prepared by CH2M HILL dated February 26, 2009. The scope of work for this Phase II ESA included completion of seven hand auger soil borings to a maximum depth of 3 ft bgs. A total of 22 soil samples were collected including two duplicates and six background samples. Two samples were collected from each boring, consisting of a shallow sample collected from 0 to 6 inches bgs and a deep sample from 30 to 36 inches bgs. One or more of the soil samples were analyzed for CAM 17 metals, organochlorine pesticides (OCPs), volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), and total petroleum hydrocarbons (TPH) quantified in the oil range (TPH- oil). The soil analytical summary table from this study is included in Appendix B. Not all of the samples were analyzed for all constituents and the background samples were not analyzed for PAHs. Many of the OCPs results were flagged due to detections between the instrument detection limits and the reporting limits. The boring locations for these samples are shown on Figure 2. Based on the analytical results, a general summary of the impacts follows: • Concentrations of PAHs above risk-based Environmental Screening Levels (ESLs) were detected in samples analyzed from the central and southern portion of the Site. Benzo(a)pyrene concentrations were detected two orders of magnitude higher than screening criteria. However, background samples were not analyzed for PAHs. • Concentrations of some OCPs exceeded risk-based screening values, Total Threshold Limit Concentrations (TTLCs), and 10 times Soluble Limit Threshold Concentrations (STLCs) concentrations, indicating special handling and disposal requirements may be required. However, most of these results were J-flagged due to detections between the instrument detection limit and the reporting limit or their relative percent differences from duplicate samples were greater than 40 percent. • Arsenic was detected in several samples at concentrations up to 6.91 milligrams per kilogram (mg/kg), which exceeded one or more risk-based screening values. However, based on several published studies, these levels are within typical background ranges for arsenic in California. All background samples contained arsenic concentrations (up to 4.10 mg/kg), which also exceeded one or more risk-based screening values. • Elevated concentrations of total chromium and lead in excess of 10 times STLCs were detected in some samples, but concentrations did not exceed risk-based screening values. PEA WP-Lodi 6 August 13,2009