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� EC0R <br /> Additional Site Assessment and Site Conceptual Model <br /> . 7-11 Store #14117 <br /> September 30, 2005 <br /> Page 3 <br /> 1 0 INTRODUCTION <br /> SECOR International Incorporated (SECOR), on behalf of 7-Eleven Incorporated (7- <br /> Eleven), presents this Site Conceptual Model (SCM) for 7-Eleven store #14117 (Site), <br /> located at 2725 Country Club Boulevard, Stockton, California (Figures 1 and 2) This SCM <br /> was prepared on behalf of 7-Eleven in response to a San Joaquin County Environmental <br /> Health Department (SJCEHD) letter dated August 23, 2004, which approved the Work Plan <br /> for Additional Site Assessment submitted by SECOR on July 24, 2004 The SJCEHD letter <br /> requested that the assessment report be submitted in the format of a Site Conceptual <br /> Model (SCM) (Attachment A) <br /> This SCM presents a discussion of site geology, hydrogeology, surface water, land use, a <br /> summary of previous and current investigations, sources of impacts, and potential <br /> groundwater receptors <br /> 1 1 OBJECTIVES <br /> This SCM has been prepared to evaluate subsurface conditions in the vicinity of the Site <br /> 2 0 SITE DESCRIPTION AND FEATURES <br /> The site is located on the north side of Country Club Boulevard west of the intersection of <br /> Country Club Boulevard and Ryde Avenue The site is currently an operating 7-Eleven <br /> convenience store and gasoline station with two 10,000-gallon underground storage tanks <br /> (UST's) as shown on Figure 2 <br /> 21 Geology <br /> Based on the description of the soil samples collected during the current assessment, the <br /> lithology at the 7-11 site consists primarily of clay and silt from grade to approximately 15 <br /> feet below ground surface (bgs) From 15 feet bgs to total depth (110 feet bgs), the lithology <br /> consists primarily of alternating layers of fine-grained sand, silt and clayey slit A 4-foot <br /> thick layer of gravelly sand was encountered in CPT-3 at approximately 75 feet bgs, but <br /> does not appear to be continuous across the site Copies of the soil boring logs are <br /> included in Attachment B and cross sections showing the underground stratigraphy are <br /> shown in Figures 3 and 4 <br /> As a result of extensive assessments and investigations conducted at the Stockton <br /> Terminals Technical Committee Facilities (STTC) site, located approximately 1 25 miles <br /> south of the 7-11 site, SECOR submitted a Corrective Action Plan (CAP) for the STTC site <br /> in April of 2003 In the April 2003 CAP, the strata beneath the Stockton area was described <br /> • as consisting primarily of interbedded clays, silts, and fine grained sands of Quaternary age <br /> 117-Eievenl7-11 Stores1141171Reports114117 SCM and Additional Assessment doc Page 3 <br />