SITE INFORMATION AND CORRESPONDENCE_CASE 2

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San Joaquin County 0.1"WN...� Environmental Health Department DIRECTOR 1868 East Hazelton Avenue Donna Heran,REHS Stockton, California 95205-6232 PROGRAM COORDINATORS Robert McClellon, REHS Jeff Carruesco, REHS,RDI • C1. y .a:P • Website: www.sjgov.org/ehd Kasey Foley,RENS F O R Phone: (209)468.3420 Linda Turkatte,REHS Fax: (209)464-0138 July 25, 2014 Mr. Bob Long Sierra Lumber Manufacturers Inc. Post Office Box 6216 Stockton, California 95207 Subject: Sierra Lumber Manufacturers, Inc. (Case No. 2) LOP Case No. 1644 375 West Hazelton Avenue Stockton, California 95203-3306 Dear Mr. Long: The San Joaquin County Environmental Health Department (EHD) received and reviewed Proposal to Incorporate Well MW-15 to DPE Operations (proposal), dated 18 December 2013, submitted by your consulting firm, Advanced GeoEnvironmental, Inc (AGE), on your behalf for the above-referenced site. The proposal had been submitted at the direction of the EHD following a telephone conversation between AGE and the EHD on 10 December 2013. In the proposal, AGE presented the scope of fieldwork necessary to connect monitoring well MW-15 to the dual-phase extraction (DPE) remediation system at a cost estimated at $2,000. AGE noted that significant declining trends had been demonstrated in DPE wells DPE-2, DPE-3, DPE-4 and monitoring well MW-9, "while there has been little to no declining trend evident from well MW-15." AGE did not provide technical justification why DPE-1, located adjacent to MW-15, had not had a significant influence reducing the contaminant concentrations detected in groundwater samples collected from MW-15, which caused the EHD some concern whether or not the addition of MW-15 to the DPE system would be effective; however, by email dated 10 January 2014, the EHD had tentatively approved the proposal to connect MW-15 to the DPE remediation system. Prior to issuing an approval letter, the EHD had requested additional information concerning concentrations detected in groundwater collected from MW-15, and the need to delineate the groundwater plume. By email dated 14 July 2014, AGE notified the EHD that MW-15 had been incorporated into the DPE remediation system on 18 February 2014. AGE included data that demonstrated that the rate of extraction of total petroleum hydrocarbon as gasoline (TPH-g) increased from one pound per day in January 2014 to nearly eight pounds per day in March 2014, following the addition of MWA 5 into the remediation system. The extraction rate increases presented by AGE are significant; therefore, the EHD approves the addition of MW-15 to the DPE remediation network, retroactive to 18 February 2014. The EHD is hopeful that these efforts will reduce the contamination concentrations detected in groundwater collected from MWA 5.