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w <br /> u <br /> Quik Stop <br /> 3555 West Hammer Lane <br /> Stockton, California 95209 Page 2 <br /> September 24, 2009 <br /> ATC proposes to install monitoring well MW-11, screened between approximaly <br /> and twenty-five feet bsg, as recommended by the EHD by letter dated Junete <br /> 5,12009. <br /> Instead of installing the monitoring well adjacent to soil boring ATC-5, as recommended <br /> by the EHD, ATC proposes to install the well adjacent to the northeast side of soil boring <br /> S131. Please provide technical justification for installing MW-11 at the proposed location <br /> directly adjacent to the northeast side of SBI, considering methyl tertiary-butyl ether <br /> collected E) was detected at at twenty feet bsg 2,90from micrograms <br /> crogra Sand liper liter (pg/L) in a grab groundwater sample <br /> boring SB1. Ing/L at twenty-four feet bsg from <br /> When installing MW-11, ATC proposes to collect soil samples at five-foot intervals for <br /> lithological evaluation; ATC also proposes to analyze soil samples collected just above <br /> the water table at approximately ten feet bsg, and where there is evidence of <br /> contamination based on readings taken from the photo-ionization detector and visual <br /> observation. The EHD concurs with these recommendations; however, the EHD <br /> disagrees with the well construction of MW-11. ATC proposes to fill the annular space <br /> with sand from total depth to approximately four feet bsg, bentonite from approximately <br /> four to three feet bsg, and Portland cement (grout) from approximately three feet to one- <br /> half foot bsg for this well screened between approximately twenty and twenty-five feet <br /> bsg. Please refer to the San Joaquin County Well Standards for guidance. <br /> Please address concerns and recommendations by the EHD and resubmit the work plan <br /> to the EHD by November 4, 2009. If you have any questions regarding this letter, please <br /> contact Vicki McCartney at (209) 468-9852 or by email at vmccartney@sjcehd.com. <br /> Sincerely, <br /> Victoria L. McCartney, REHS Nuel C. Henderson, Jr., PG <br /> Senior Registered Environmental Health Specialist Engineering Geologist <br /> End: <br /> c: Scott Perkins, ATC Associates Incorporated, 6602 Owens Drive, Pleasanton, <br /> California 94588 <br /> Mr. James L.L. Barton, PG, California Regional Water Quality Control Board Central <br /> Valley Region, 11020 Sun Center Drive, Suite 200, Rancho Cordova, California <br /> 95670 <br />