SITE INFORMATION AND CORRESPONDENCE FILE 2

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ARCO Service Station No. 2186 Page 2 3212 North California Street February 5, 2009 Stockton, California 94570 The EHD also approves the installation of MW-1D as proposed by Stantee in the Addendum. This deep well will be advanced to approximately sixty-five feet bsg using eight-inch diameter hollow-stem augers followed by advancing the soil boring to the same depth of approximately sixty-five feet using fifteen-inch diameter hollow-stem augers centered on the eight-inch pilot boring. Following this, an eight-and-five-eighths-inch diameter, flush-threaded steel conductor casing will be installed to sixty-five feet bsg and the neat cement and/or grout installed within the annular space using a tremie pipe will be cured for at least twenty-four hours. Then eight-inch diameter hollow-stem augers will be used to advance the boring down the inside of the conductor casing to total depth of approximately eighty-five feet bsg, setting deep well MW-1D with a screen between approximately seventy and eighty-five feet bsg. Although the narrative states that "the deep well will be constructed of two-inch diameter, flush-threaded, schedule 40 PVC well casing with 20 ft of 0.020-inch factory-slotted well screen set at depths of 70 to 85 ft bs9," Figure 2 illustrates that the deep well will have a fifteen-foot screen between seventy and eighty-five feet and be constructed using four-inch diameter schedule 40 casing. In spite of these contradictions, the EHD recommends that the deep well be constructed with a fifteen-foot screen and two-inch diameter casing. The EHD also recommends that 93 sand be used with 0.020-inch-slotted casing instead of the proposed 2/12 sand. Stantee recommended that vapor wells VW-IA through VW-3A be removed from the groundwater monitoring and sampling program since depth-to-water measurements have historically been reported below the screen intervals for these wells. The fact that groundwater can not be collected from these wells has already resulted in these wells being removed from the sampling program. These wells may be removed from the quarterly monitoring and sampling events as long as depth-to-water measurements indicate that these wells are dry. However, if groundwater rises to within the screen intervals of VW-1 A, VW-2A, and VW-3A, these wells must be monitored and sampled. Please submit a well destruction permit application and permit fee of $60 along with a boring permit application and permit fee of $89 to the EHD and complete the fieldwork by April 15, 2009. If you have any questions regarding this letter, please contact Vicki McCartney at (209) 468-9852, or by e-mail at vmccartney@sjcehd.com. Sincerely, Victoria L. McCartney, Senior REHS Nuel C. Henderson,Jr.,PG Senior Registered Environmental Health pecialist Engineering Geologist c: Mr. Rusty Benkosky, PE, Stantec Consulting Corporation, 3017 Kilgore Road, Suite 100, Rancho Cordova, California 95670 Mr. James L.L. Barton, PG, California Regional Water Quality Control Board Central Valley Region, 11020 Sun Center Drive, Suite 200,Rancho Cordova, California 95670