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• • ENCON Environmental Page 2 of 4 Hydrogeology The subject property's physical location was researched employing a United States Geological Survey (USGS) 7.5 Minute Topographic Quadrangle (Quad) Map relevant to the subject property. The USGS 7.5 Minute Quad Map has an approximate scale of 1 inch to 2,000 feet, and may show physical features with environmental significance such as wetlands, water bodies, roadways, mines, and buildings. The elevation of the property is approximately 18 feet above mean sea level.There is a regional downslope to the west. The site is located within the San Joaquin Valley, part of the Great Central Valley Geomorphic Province of California. The site area is underlain by Pleistocene alluvial deposits. The site is located with in the San Joaquin Valley Groundwater Basin. The site is within the Calaveras River Watershed. A property located approximately 100 feet to the south(1207 Aurora Street) reported depth to water ranging from 20 to 30 feet with a southerly flow direction(JJW Geosciences,Inc.,2009). While groundwater flow direction at the subject property cannot be confirmed without survey measurement of static groundwater level at triangulated points, it is expected to flow in the direction of surface topographical contour, or toward the wetland or nearest water body or discharge basin (percolation channel). It is important to note that groundwater flow direction can be influenced locally and regionally by the presence of local wetland features, surface topography, recharge and discharge areas, horizontal and vertical inconsistencies in the types and location of subsurface soils, and proximity to water pumping wells. Depth and gradient of the water table can change seasonally in response to variation in precipitation and recharge, and over time, in response to urban development such as storm water controls, impervious surfaces, pumping wells, cleanup activities, dewatering, seawater intrusion barrier projects near the coast, and other factors. Scope of Work A total of eight soil borings are proposed. Soil borings will be drilled at areas of current and past auto repair operations at the site. Soil samples will be collected at 5-foot intervals to maximum depths of 20 feet. Soil samples will be screened in the field for volatile organic compounds using a Photoionization detector. Two soil samples from each boring will be selected for analysis of contaminants of concern. Since past auto repair operation locations are not well-documented during the former building structure occupancy on the site (1960's to 1990's), the analysis of selected samples for contaminants of concern will be based on field observations. A total of 8 soil samples will be analyzed for TPH as diesel and gasoline, BTEX, and MTBE,using EPA Method 8015 and 8260B; and a total of 4 soil samples will be analyzed for TPH full scan, volatile organic compounds, and Title 22 metals using EPA Method 8015, 8260, and 6000/7000 series. The attached Figure 2 illustrates the preliminary soil boring locations. Pre-drilling Activities • Perform Site Visit to verify existing conditions and pre-mark boring locations and notify Underground Service Alert(USA)of the intent to excavate or drill and use standard care to avoid potential damage to subsurface utilities. • A Site-specific Health and Safety Plan(Level D Health&Safety according to OSHA CFR 1910.120, will be prepared. • Submit a Drilling Permit Application to the San Joaquin County Environmental Health Department