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INECHWED <br /> -.') EDNUNoa G. BROwry Jr;. <br /> OCT 209 <br /> cA`eroexeAEWRONMENTAL HMTH <br /> SMECATRErHEw ROD <br /> RIOUE <br /> TARY FOPPEME 'r ENVIROMENTAL PROTEC <br /> Water 410T <br /> VArds <br /> 0 <br /> Central Valley Regional Water Quality Control Board <br /> 5 October 2017 <br /> Dennis Leikem <br /> Environmental Manager <br /> Musco Family Olive Company <br /> 17950 Via Nicolo <br /> Tracy, CA 95377 <br /> REVIEW OF WELL INSTALLATION REPORT AND DETECTION MONITORING PROGRAM <br /> EVALUATION, MUSCO FAMILY OLIVE COMPANY, SAN JOAQUIN COUNTY <br /> The Class II Surface Impoundments at the Musco Family Olive Company (Musco) are regulated <br /> by Waste Discharge Requirements (WDRs) Order R5-2014-0125. Central Valley Water Board <br /> staff reviewed the Well Installation Report and Detection Monitoring Program Evaluation (I&E <br /> Report) submitted on behalf of Musco by Terraphase Engineering Inc. (Terraphase) on 31 July <br /> 2017. The 1&E Report provides a description of activities for overdrilling monitoring well MW-22, <br /> completing soil boring SB-3 and well locations MW-36 and PZ-1, and installing Lysimeter 36R. <br /> This work was completed following the Detection Monitoring Program (DMP) Evaluation and <br /> Work Plan (Work Plan) as conditionally approved by staff on 4 April 2017. <br /> Terraphase provides the following construction information in their I&E Report: <br /> • Monitoring Well MW-22 was overdrilled using sonic drilling methods from 111 feet to <br /> 160 feet.bgs. An intermediate water bearing zone was not identified at this location, and <br /> Terraphase concluded that a monitoring well was not necessary for construction at this <br /> location. The boring was subsequently backfilled with cement grout. The intent of deepening <br /> MW-22 was to monitor the same water bearing zone screened in downgradient wells <br /> MW-20R and MW-21 R. Therefore, with the elimination of MW-22, all shallow zone wells are <br /> currently dry and only MW-1 OR, -18R, -20R, and -21 R remain to monitor the intermediate <br /> zone. <br /> • Soil boring SB-3 was advanced northeast (downgradient) of the Surface Impoundment C <br /> sump with the intent of installing monitoring well MW-34R. Hollow stem drilling methods <br /> were employed, and soil samples were collected every five feet from 85 feet to 105 feet bgs, <br /> and every 2.5 feet from 105 to 145 feet bgs. Additionally, sampling was increased to <br /> continuous recovery while drilling through sands and gravels in an attempt to identify the <br /> depth of first encountered groundwater. At a total depth of 145 feet bgs, a water bearing <br /> zone was not identified. The boring was left open overnight and no water was reported to be <br /> detected in the boring the next morning. The boring was backfilled by filling with cement <br /> grout. <br /> • Monitoring well MW-36 was drilled north of the Surface Impoundment D sump to confirm the <br /> depth of the shallowest water bearing zone at Surface Impoundment D, and provide <br /> gradient information of the water bearing zone detected at MW-35R. MW-36 was advanced <br /> using hollow stem auger drilling methods and the first encountered water was identified at <br /> 135 to 136 feet bgs. Total depth was terminated at 145 to confirm a confining layer beneath <br /> KARL E. LONGLEY SCD, P.E., CHAIR I PAMELA C. CREEDON P.E., BCEE, EXECUTIVE OFFICER <br /> 11020 Sun Center Drive#200,Rancho Cordova,CA 35670 1 www.waterboards.ca.gov/oentralvalley <br /> C'&RECYCLED PAPER <br />