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KLEINFELDER 1 EXECUTIVE SUMMARY 1 i This report summarizes Kleinfelder's Phase II Environmental findings for the San Joaquin County Mosquito & Vector Control District (SJC/MVCD) facility located at 200 N. Beckman Road in Lodi, California. The Phase II work was requested to update current conditions at the j site and address selected concerns from former environmental assessments previously conducted at the site (See Background Section). Kleinfelder's assessment included the installation of four monitoring wells and advancement of three soil borings to depths ranging from 30 to 50 feet in the former underground storage tank (UST) areas. Near surface soil sampling was conducted in a washdown area, chemical storage area, pond area and former UST soil stockpile. The monitoring wells were surveyed, developed and subsequently sampled. Soil and groundwater samples were submitted for various analyses (See Section 4). The Phase II work included an evaluation of potential offsite sources of contamination. A total of four groundwater samples, six composite soil samples and 22 discrete soil samples were analyzed for various analyses as listed in Section 4. A summary of the analytical results are I located in Tables 2 through 8 and sampling locations are illustrated on Plate 3. Based on the fi reported analytical results and field observations during sampling, the following is a brief summary of Kleinfelder's findings: ❑ Depth to groundwater was measured approximately 55 to 60 feet below ground surface (bgs). Depth to groundwater was evaluated to be southwest at a gradient of approximately 0.010 to 0.012 ft/ft. ❑ One of the four groundwater samples collected from the four monitoring wells had elevated levels of petroleum constituents. This sample was collected from MW-4, which according to groundwater elevations is situated down-gradient of a former Shell/Econo 5 Gas station located at 880 Victor Road (north of site). Based on this information, it appears that the current and/or past operations of the adjacent gas station are impacting groundwater beneath the northern portion of the site. ❑ Soil and groundwater samples were collected in two former onsite UST areas where petroleum impacted soil has been excavated. Based on analytical results and Kleinfelder's field observations, petroleum impacted soils remain in the eastern portion of the southernmost UST area (See Plate 4) at depths ranging from approximately 25 to 45 feet below ground surface (bgs). Analytical results reveal a marked decline in petroleum { concentrations at 40 feet to non-detect levels at 50 feet. Groundwater samples were none detected for requested petroleum constituents in this area. ❑ Kleinfelder recommends shallow excavation of petroleum impacted soil in the washdown area followed by confirmation soil sampling. The excavated soil in the washdown area and petroleum impacted stockpiled soil from the former UST area should be disposed of according to local and federal regulations. For additional conclusions and recommendations and discussion of findings please refer to Sections 5 and 6. 36274/ST03RI919 Page 1 of 19 �c;2004 Kleinfelder,Inc. January 5,2004