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1 February 26, 2001 52822 1 Michael Infurna, Senior REHS ' San Joaquin County Public Health Services Environmental Health Division Page 2 i by pressure grouting in accordance with the following procedures. The wells will be destroyed by a state- licensed C57 well driller under the direction of a Harding ESE geologist or engineer. The wells will be sounded to insure that no obstructions are present to interfere with filling or sealing. The wells will then be pressure grouted with a tremie pipe from the bottom.up,to a depth of approximately three feet bgs. The grout will consist of neat cement mix of less that 6 gallons of clean water-per sack of cement, and less than five percent powdered bentonite. The top of the 2-inch diameter well casing will be drilled out with`an 18 cl diameter solid flight-auger to a depth of approximately`3 t bgs%Cuttings will be 2 S removvlce from the bottom of the over-bored Additional grout will be added to fill the settled grout in the-casing and allowed to fill the bottom foot f the excavation. The remaining portion of the excavation will be backfilled with native soil`cuttings. Monitoring well MW-7 was installed within impacted soil which was first encountered at a depth of 12.5 I feet bgs just beneath the former UST excavation. Non-impacted soil is present above this depth within the former UST excavation. The presence of impacted soil below i2.5 feet bgs requires that MW-7 be over-drilled to just beyond the total depth of 41.5 feet bgs. Non-impacted cuttings from above 12.5 feet bgs will be distributed around the bare ground surface of the well. Impacted cuttings will be drummed and disposed of in compliance with local, state, and federal environmental and transportation regulations. The resulting borehole will be tremie grouted to three feet bgs and the top 3 feet will be filled with clean cuttings. Because the groundwater in this well(and all wells) is non-impacted(non-detectable concentrations for all required analytes including fuel oxygenates and 1,2-dichloroethne, Tables 1, 3, and 6(HLA, 1999)), at the PHS/EHD inspectors discretion.the displaced water will be allowed to seep into the bare ground around the well or placed in a barrel for later disposition by seepage into the bare ground surface nearby. The well destruction procedures will be performed by Woodward Drilling Company of Rio Vista, California a C-57 licensed(710079)well driller. The well destruction is tentatively scheduled for March 2,2001,and this letter constitutes the required 48 hours advanced written notification. Enclosed are the completed application for well destruction, $60.00 in permit fees; and site location.maps showing the Site and well locations. . 5 1 J Harding ESE A MACTEC COMPANY