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' 08 November 2005 i AGE-NC Project No. 98-0481 ' Page 5 of 8 The Modesto, Riverbank,Turlock Lake Formations and overlying recent alluvium are the principal source of domestic ground water in the 13,500 square-mile San Joaquin Valley Groundwater Basin, which is drained primarily by the San Joaquin River(Basin 5-22). Escalon lies within the Modesto Groundwater Sub-basin, which is drained primarily by the Stanislaus River, which drains into the 1 San Joaquin River. According to the findings of AGE's sensitive receptor survey the closest potential receptor is a tmunicipal well (Identified as municipal well #1) located at the end of Roosevelt Street, approximately 1,700' southeast from the site. Due to the significant distance between the site and ' municipal well #1 and minor impacts to soil and lack of impact to ground water, there does not appear to be a significant concern regarding the location of well. No other receptors noted in the survey appeared to raise a significant concern or threat to human health. 2.5. SOIL PROFILE In general,the soil stratigraphy beneath the site consists of interbedded units of fine-grained soil(i.e., silt) and coarse-grained soil (i.e., sand). As shown on Figure 3 and Figure 4, silty sand was encountered from surface grade to depths ranging from approximately 5 to 8 feet bsg.The silty sand layer appears underlain by soil composed of silt with sand extending to depths of approximately 10 to 15 feet bsg. The layer of silt was underlain by coarse-grain soil composed of sand, sand with silt ' and silty sand which extended to a depth of approximately 25 feet bsg.However,in soil boring S13-3, a unit of sand with silt was described from approximately 10 to 23 feet bsg. Silty clay and silt with sand was encountered at 25 feet bsg, and from 40 to 50 feet bsg; soil samples were not collected ' between 25 and 40 feet bsg. Lines of cross-section are presented in Figure 5. Boring logs are included in Appendix B. 2.6. GROUNDWATER HYDROLOGY ' Based on the information obtained from assessment activities,depth to ground water in the vicinity of the site is approximately 60 feet bsg.Regional ground water flow direction is generally northwest ' to north-northeast; however, both ground water depth and flow direction can vary locally and seasonally.During drilling of soil boring SB-4,ground water was first-encountered at approximately 59 feet bsg. 4.0. FINDINGS ' Soil descriptions were utilized to construct the vertical and lateral soil model; laboratory analysis of • soil and ground water samples were utilized to assess the hydrocarbon-impact on the two media. ' Advanced GeoEnvironmental,Inc..