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EDMUND G. BROWN JR <br />GOVERN,' <br />al%) 1St <br />nITTrrHAE:' ,R.0DR IQ UEZ <br />ENVIRONMENTAL PROTECTION <br />r.:7:NN•00# <br />Water Boards <br />Central Valley Regional Water Quality Control Board <br />6 September 2017 <br />Mr. Carl Knowles <br />P.O. Box 640 <br />Woodbridge, CA 95258 <br />.42,{ <br />e-c-• <br />REVIEW OF WORK PLAN FOR OFFSITE MONITORING WELL INSTALLATION, <br />KNOWLES STATION, 1120 WEST HAMMER LANE, STOCKTON, SAN JOAQUIN COUNTY, <br />CASE #390107 <br />Central Valley Regional Water Quality Control Board (Central Valley Water Board) staff <br />reviewed the 28 August 2017 Work Plan for Offsite Monitoring Well Installation (Work Plan) <br />submitted by Stratus Environmental, Inc. (Stratus) on behalf of the Knowles Family Trust for the <br />unauthorized underground storage tank (UST) release at 1120 West Hammer Lane in Stockton, <br />San Joaquin County (Site). The Work Plan proposes to install one groundwater monitoring well <br />(MW-13) north-northeast of the Site, on the property at 1015 West Hammer Lane. In the event <br />that an access agreement cannot be obtained from the property owner at 1015 West Hammer <br />Lane, the well will be installed in the City of Stockton sidewalk on the north side of West <br />Hammer Lane. <br />The Work Plan proposes to collect soil samples from approximately 30 feet below ground <br />surface (bgs), 40 feet bgs, and 50 feet bgs during boring advancement. The Work Plan <br />proposes to construct well MW-13 using 2-inch diameter polyvinyl chloride (PVC) casing and <br />20 feet of 0.02-inch factory slotted well screen from approximately 30 to 50 feet below ground <br />surface (bgs). The Work Plan proposes to develop well MW-13 by surging with a bailer followed <br />by groundwater pumping. Groundwater samples will be collected from well MW-13 following <br />well installation and development. The Work Plan proposes that soil and groundwater samples <br />be analyzed for gasoline range petroleum hydrocarbons (TPHg), benzene, toluene, <br />ethylbenzene, xylenes (collectively "BTEX"), methyl tertiary butyl ether (MTBE), naphthalene, <br />and the lead scavengers 1,2-dibromoethane and 1,2-dichloroethane. <br />Central Valley Water Board approves the Work Plan with the following conditions: <br />During the second quarter 2017 groundwater monitoring event, Stratus recorded depth <br />to groundwater readings ranging from 28.44 to 30.75 feet bgs. Installation of the MW-13 <br />well screen from 30 to 50 feet bgs may result in the well screen being fully saturated. To <br />ensure that the groundwater table is captured within the MW-13 screen interval, Central <br />Valley Water Board requests that the top of well screen be installed approximately five <br />feet above first encountered groundwater during well installation activities. <br />To ensure that MW-13 is properly developed, Central Valley Water Board requests that <br />a surge block be employed during monitoring well development. <br />If you have any questions or comments, please contact me at (916) 464-4707 or via e-mail at <br />geoff.rader@waterboards.ca.gov. <br />KARL E. LONGLEY ScD, P.E., CHAIR I PAMELA C. CREEDON PE., BCEE, EXECUTIVE OFFICER <br />11020 Sun Center Drive 5200, Rancho Cordova, CA 95670 www.waterboards.ca.pov/centralvalley <br />CO RECYCLED PAPER