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1.0 INTRODUCTION <br />This report is being submitting n behalf of C. M. Weber Enterprises, <br />Inc. to present the Remedial ction Plan (RAP) for groundwater <br />impacted with petroleum hydroca ns at the facility located at 141 <br />North El Dorado Street in Sto ton, California (Figural). The <br />project site is the future loc tion of a fourteen story building <br />which will be the beginning of the revitalization of downtown <br />Stockton. The report provides background information, summarizes <br />results of rzcant investigations presents an evaluation of remedial <br />alternatives, and outlines a proposed remedial action plan for the <br />impacted groundwater. <br />2.0 SITE BACKGROUND <br />In 1955, S:zell oil Company const <br />facility at 141 North El Dorado <br />construction included the inst; <br />u;,ucrground product storage tZ <br />gasoline. one 500 -gallon under <br />oil was also located on the pri <br />tanks was removed and two 7,500 <br />inst - fled to store unleaded g <br />sealing gasoline in 1981 and f:-- <br />removed. <br />._removed. No soil samples were c <br />the tank removal. Following re <br />pit excavation .was backfilled <br />remained nn site and w38 In use <br />!i <br />'�: 3.0 HYDROGEOLOGIC SETTING <br />^, The site lies in the eastern pos <br />' Delta. The subsurface geology <br />by Pleistocene and Recent alluvi <br />consist of heterogeneous sequen <br />from active stream channels, a <br />overbank and marsh depositional <br />>, <br />ucted a retail gasoline and service <br />treat in Stockton (Figure 2). Thi,- <br />lation of four 4,000 -gallon .steel`., , <br />ks for the .-ontainment of leaded <br />sound storage tank containing used- f <br />terty. In 1953, one of the leaded <br />{lion underground storage tanks were ` } <br />ooline. The station discontinued'.-',-. � <br />: of the product storage tanks were ! <br />llectec: and analyzed at the time -of, <br />ival of the storage tanks, the tank <br />and repaved. The used -oil tank <br />tntil June of 1990. <br />ion of the Sacramento - San Joaquin r, <br />the Stockton area is characterized <br />L deposits. These alluvial deposits, <br />ss of sands and gravels originating <br />I silts and clays originating from <br />;nvironments. } <br />According to the San Joaquin County Flood Control and Water <br />Conservation District, Spring 195 0, the regional groundwater gradient <br />is to the east — northeast. <br />The nee.rest surface water body to the site is the Stockton Deep Water <br />Channel which trends east to West and is connected to the Sacramento <br />- San Joaquin Delta. The east end of the channel terminates Just <br />west of the site at Center Street. The site itself overlies the <br />former east end of the chanial. The site is also located <br />approximately 2.75 miles south f the Ca'&veran River and 2.5 miles <br />north of Walkar Slough, a tribe ary of the San Joaquin River. <br />A survey of all water wells "' <br />conducted based on informa <br />Veber Point Property - 475 <br />820RAP741.TLP <br />1 <br />a one -mile radios of the site was <br />.revel- ,ed from the California <br />