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Ze <br /> ATC Associates Inc. <br /> VYJ TC 1117 Lone Palm Avenue, Suite <br /> Modesto, California 953511 <br /> 209-579-2221 <br /> fax: 209-579-2225 <br /> June 22, 2007 <br /> 54.62514 .0001 <br /> Mr. Mark Owens H EC I1- V/ 0), <br /> California Underground Storage Tank Cleanup Fund JUN20071001 I Street 17a' Floor <br /> Sacramento, California 95814 ENVIRONMEN F HEALTH <br /> RERMlT/SERVICES <br /> Subject: Pre-approval for Proposed Double-Cased Monitoring Well <br /> King Island Resort - 11530 West Eight Mile Road, Stockton, California <br /> Site Code: 1557 RO#: 309 SWRBC-CUF#: 003668 <br /> Dear Mr. Owens: <br /> ATC Associates Inc. (ATC) respectfully requests your assistance in the matter of a cost <br /> eligibility review. Pursuant to a directive issued by the San Joaquin County Environmental <br /> Health Division (SJCEHD), dated January 2, 2007, ATC prepared the Workplan for Vertical and <br /> Lateral Subsurface Investigation, King Island Resort - 11530 West Eight Mile Road, Stockton, <br /> California dated January 19, 2007, and an addendum to the workplan (April 18, 2007) which <br /> provided more detailed information pertaining to installation of a proposed double-cased well to <br /> be installed to an estimated depth of 120 feet below grade surface. This work is part of <br /> assessment activities being conducted on behalf of Westrec Properties, as requested by Mike <br /> Infuma of the SJCEHD. The drilling techniques and well completion specifications associated <br /> with the double cased well, detailed below, are more specialized than routine drilling procedures. <br /> Additionally, the proposed monitoring well will serve as a sentinel well and will be installed <br /> approximately 50 feet from a sole source potable well that services the King Island Resort <br /> marina. For these reasons, ATC is requesting a cost eligibility review prior to initiating the <br /> work. ATC requested bids from four drillers, of which two submitted bids and two declined, see <br /> attached. <br /> The primary reason for proposing a double cased sentinel well is to maintain the integrity of the <br /> existing potable well. A double conductor casing is proposed so as to minimize the potential for <br /> vertical contaminant migration during and after installation of the sentinel well. Previous <br /> investigation activities conducted at the site indicate there are potentially four groundwater. <br /> bearing zones that are situated between layers of silty/clayey sediments that may act as <br /> aquatards. A grab groundwater sample collected from a depth of 22 feet below ground surface <br /> (bgs) in a cone penetration test (CPT) boring advanced in the vicinity of the existing potable well <br /> contained MTBE. MTBE was not detected in a grab groundwater sample collected from a depth <br /> of 105 feet bgs in the same CPT boring. <br /> The outer casing of the proposed sentinel well is intended to seal off petroleum impacted <br /> groundwater within 50 feet of the ground surface. The purpose of the deeper inner casing is to <br /> seal off groundwater present between 50 and 98 feet bgs, as the existing potable well was <br /> 1 ATC Associates Inc. <br /> S:\Environmental\62514.0001\Pre-approval.doc - <br />