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? _ IL _. .. N%Woo/ San Joaquin County Environmental Health Department DIRECTOR -=•�J Donna Heran,REHS z. 1868 East Hazelton Avenue Stockton, California 95205-6232 PROGRAM COORDINATORS . Robert McClellon,REHS ` Jeff Carruesco,REHS,RDI c .• p q��Fo.Ra\ Website: www.sjgov.org/ehd Kasey Foley,REHS Linda Turk tte,RENS Phone:zz(209)468-3420 F Apri101gg� ,426s01438 Mr. Jose Rios 7-Eleven, Incorporated Post Office Sox 711 Dallas, Texas 75221-0711 Subject: 7-Eleven Store No. 19976 1399 North Main Street Manteca, California 95336 The San Joaquin County Environmental Health Department (EHD) has received and reviewed Work Plan for Well Destruction (work plan), dated 18 February 2014, prepared and submitted by your consulting firm, Stantec Consulting Services Inc. (Stantec), on your behalf for the above- referenced site. The work plan was submitted in response to the EHD letter dated 24 December 2013 directing a well destruction work plan be submitted to this agency. In the work plan, Stantec proposes to destroy monitoring well MW-2 and nested wells MW-1/MW-1A and SP-1/SP-1A by over-drilling; soil gas probes SG-12 through SG16 by hand tools and air-knife/vacuum equipment; and MW-3, MW-4, MW-4A, MW-5, MW-5A, MW-7, MW-8, SP-2 and SP-3 by pressure grouting. Stantec proposes to capture groundwater displaced to the surface for disposal "or depending on the quantity, it (displaced groundwater) may be used to mix additional grout". Stantec proposes to apply approximately fifteen pounds per square inch (psi) of pressure to the cement grout for a period of five minutes during the pressure grouting process followed by removing the well box and the top three to five feet of well seal and casing. The EHD approves the work plan with the following conditions: • Over-drill MW-5A instead of pressure grouting this well since contaminants of concern were detected in soil samples collected at thirty feet below surface grade (bsg) during the well installation; based on the remote location of MW-5A, soil in this area may not have benefitted from remediation performed at this site; Pressure grout MW-6; this well was inadvertently omitted from the well destruction list; When destroying wells by pressure grouting, remove only the top three feet (not five feet) of well seal,and"soil; it is difficult to cut the casing at depths greater than two-and- a-half feet prior to inserting the grout; • Use only potable water to make the grout; displaced groundwater may not be used to make grout or for any other purpose and must be disposed of properly; • Apply at least 25 psi of liquid grout pressure for ten minutes when pressure gr uting the wells; destroy the wells by over-drilling if the well casings are unable to withsta this pressure for this length of time; RECEIVED APR 2 21014