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O� 1-'.. :; Eouurr G dllovn.dF <br /> CA lII OANI♦ <br /> Water Boards �✓ t""'"``u <br /> Central Valley Regional Water Quality Control Board <br /> 17 December 2018 <br /> Ralph Lee White Peter Bui & Kimberly Hoang <br /> 2201 E. 81h Street 4004 Maddie Circle <br /> Stockton, CA 95206 Stockton, CA 95209 <br /> RALPH'S SQUARE, 2122 S. AIRPORT WAY, STOCKTON, SAN JOAQUIN COUNTY, CASE# <br /> 390995 <br /> Central Valley Regional Water Quality Control Board (Central Valley Water Board)staff reviewed the <br /> Off-Site Assessment Work Plan(Work Plan)dated 30 November 2018, submitted by Advanced <br /> GeoEnvironmental Inc. (AGE)for the Ralph's Square unauthorized petroleum release at 2122 <br /> S.Airport Way in Stockton(Site).. In-the Work Plan, AGE proposes to install two monitoring wells <br /> off-Site to the east to delineate the lateral extent of hydrocarbon impact to groundwater <br /> downgradient of the Site. The two monitoring wells are proposed as follows: <br /> Total Depth Screen Interval <br /> Soil Sam lin Well Sampling <br /> Depth Analysis Frequency <br /> (ft b s (ft b s (ft b s <br /> 50 25-50 5ft intervals from 5ft Lithologic Quarterly for <br /> to Total Depth logging only 4 quarters <br /> ft bgs=feet below ground surface <br /> Central Valley Water Board staff concurs with the proposed scope of work,with the following <br /> comments: <br /> 1. Central Valley Water Board staff typically request that monitoring wells which intersect the <br /> water table be constructed with a 15-foot screen interval with approximately 5 feet above and <br /> 10 feet below the water table. However, depth to water at the Site has increased <br /> approximately 17 feet in the past 16 years, and has fluctuated greatly in the past 4 years <br /> (from 25.70 to 33.97 feet below top of casing). As such, while the proposed screen length of <br /> 25 feet is excessive, a longer than usual screen interval is reasonable at this Site. <br /> 1 <br /> Please install these wells with 20 feet of screen, with approximately 5 feet above and 15 feet <br /> below the water table. The actual installed screen depth should be based on depth to water <br /> and subsurface conditions observed during installation. <br /> 2. As not specified in the Work Plan, please wait a minimum of 48 hours after installation to <br /> develop the monitoring wells. <br /> KARL E LONGLEY SCD. P.E.,CHAIR j PATRICK PULLIVA,ESU.,E:/ECLITIVE OFFICEF <br /> :1020 Sun Gemer Drive 9200.Ranrno CurtlovN.CA 95570 ,vv:w.vixtetboerds.ca.yavlcen«alvllllry <br />