Laserfiche WebLink
EDMUND <br />G, BROWN Jn. <br />C P I v O w H I P 0 7 2.014 TT <br />MAHEW ROORIQUE2 <br />Water Boards ` <br />� JUL 6ECRETARv FOR <br />FNVIRONMF NTAI PROiFCTION <br />RORtM _ -- <br />Central Valley Regional Water Quality Control Board EN PERMIT/SERVICES <br />3 July 2014 <br />Ralph Lee White <br />2201 East Eighth Street <br />Stockton, CA 95206 <br />Peter Bui & Kimberly Hoang <br />4004 Maddie Circle <br />Stockton, CA 95209 <br />WELL INSTALLATION WORK PLAN, RALPH'S SQUARE, 2922 SOUTH AIRPORT WAY, <br />STOCKTON, SAN JOAQUIN COUNTY, RB CASE # 390995 <br />California Regional Water Quality Control Board, Central Valley Region (Central Valley Water <br />Board) staff reviewed the Well Installation Work Plan (Work Plan) received on 24 June 2014. <br />The Work Plan was prepared on your behalf by Advanced GeoEnvironmental, Inc.(AGE). In <br />the Work Plan, AGE proposed installation of 3 shallow groundwater monitoring wells east of <br />your property to evaluate the extent of petroleum impacts caused by the unauthorized release of <br />fuels from the former underground storage tank (UST) system. The three wells are proposed to <br />be installed along Phelps and Spring Streets. I concur with the Work Plan as proposed with <br />conditions as described below. <br />Our comments on the Work Plan are as follows; <br />1. Deeper monitoring wells should be constructed adjacent to the 3 proposed shallow wells <br />to address vertical delineation of petroleum impacts from this site. AGE proposes to <br />construct three shallow monitoring wells to evaluate the lateral extent of petroleum <br />impacts found in groundwater at about 31 feet below ground surface (bgs) with wells <br />screened from 30 to 50 feet bgs. Vertical delineation at this Site is currently <br />characterized by one deep well (MW -11) screened between about 100-110 feet bgs. <br />Results from the deep well show petroleum hydrocarbons concentrations below <br />laboratory detection limits. However, cone -penetrometer data (CPT), collected in 2007, <br />indicated methyl -t -butyl ether (MTBE) was detected in a soil sample collected at 67 feet <br />bgs at a concentration of 0.03 mg/kg . The soils between 50 and 60 feet bgs are <br />described as silty sand and wells set with 10 foot of well screen between 55 and 65 feet <br />bgs should be constructed within 10 feet of the shallow wells to monitor pollutant <br />concentrations at depth and used to evaluate vertical gradients in the area. <br />2. Please construct shallow monitoring wells with 5 feet of screen section above the water <br />table and 15 feet of screen below the water table to allow for fluctuations in water levels. <br />3. Soil sampling in the areas proposed for well installations is not necessary. The purpose <br />for collecting soil samples would be to identify petroleum concentrations in the vadose <br />zone that may cause impacts to the underlying groundwater. Since these well locations <br />are over 200 feet from the source of the pollution there is no expectation there will be <br />KARL E. LOtJOLEY SCD, P.E., CHAIR I PAMELA C. CREEDON P.E., DCEE, EXECUTIVE OFFICER <br />11020 Sun Center Drive #200, Rancno Cordova, CA 95570 1 wwwwaterboards cagov/centralvalley <br />`i nCCYCLCD rArCn <br />