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1 <br /> SITE INVESTIGATION WOR"LAN <br /> approximately 13 feet below ground surface. Depth to regional groundwater is approximately 25 <br /> feet below ground surface (Margaret Lagoria, SJCEHD). <br /> ' TOPOGRAPHY AND SURFACE FEATURES, I.E. WATERCOURSES, <br /> LAKES, AND GROUNDWATER RECHARGE FACILITIES <br /> The USGS Stockton West, California 7.5 minute quadrangle, edition of 1968, indicates the site is <br /> relatively level with an elevation of approximately 8 to 9 feet above mean sea level (amsl). The <br /> surface gradient as shown on the topographic map appears to be in a northeasterly direction. No <br /> 1 watercourses or lakes are depicted on or adjacent to the site. The Calaveras River is located <br /> approximately 1,800 feet north of the site. The condition of the site with respect to aquitards, <br /> aquicludes, and perched water zones has not yet been determined. <br /> 1 _ <br /> SAMPLING AND ANALYSIS PLAN <br /> ' The objective of the investigation proposed under this workplan is intended to determine the <br /> vertical and lateral extent of MTBE in the soil and groundwater and whether it will be necessary <br /> to conduct further investigation or remediation. <br /> SOIL AND GROUNDWATER SAMPLING <br /> 1 NUMBER AND LOCATION OF SOIL BORINGS <br /> Approximately five (5) soil borings will be advanced to the soil-groundwater interface. Exact <br /> locations and total number of borings will be dependent on observed field conditions. At this <br /> time, ESA proposes that one soil boring will be advanced in the center of the former tank pit with <br /> four additional borings advanced at locations approximately 15 feet from the tank pit corners. <br /> The locations of the proposed soil borings are provided in Figure 4 attached to this document. <br /> Prior to commencement of field activities, the area will be cleared for utilities through the <br /> Underground Service Alert (USA) system, as required by law. <br /> SOIL SAMPLING METHOD, DEPTH AND NUMBER OF SAMPLES <br /> 1 Direct-push soil sampling technology will advance the soil borings to desired depths. This <br /> drilling method will provide a full-length soil core extending from the surface to the groundwater <br /> 1 interface. (ince the soil core is extracted, the field geologist will describe and record the soil <br /> types and characteristics such as odor, staining, or signs of fill material. Select sections of the <br /> recovered soil core will be removed from the continuous core sections, sealed with Teflon and <br /> end caps and placed in cooled storage prior to transportation to a state-certified analytical <br /> laboratory. Two soil samples per soil boring will be submitted for chemical analysis of MTBE. <br /> The soil samples will be representative of the general lithology and soil conditions. At this time, <br /> it is expected that soil samples intended for laboratory analysis, will be obtained from depths of 8 <br /> and 15 feet (expected groundwater interface) below the ground surface. These depths may vary <br /> due to soil conditions and sample recovery. However, ESA will endeavor to collect soil samples <br /> t Environmental Science Associates 4 University of'the Pacific-Site brvestigation Work Plan <br /> June MOO 200252 <br />