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STATE OF CALIFORNIA—ENVIRONMENTAL PROTE AGENCY ` PETE WILSON Governor <br /> DEPARTMENT OF TOXIC SUBSTANCES CONTROL <br /> 10151 CROYDON WAY,SUITE 3 <br /> SACRAMENTO,CA 95827-2106 <br /> (916) 855-7700 <br /> December 19, 1991 <br /> I{ f �iyt^' L1✓y.4 <br /> vi„f, ' 1991 <br /> Mr. Marshall Cloud UES 2 3 <br /> Defense Distribution Region West, AL HE OV' <br /> Tracy Site ENVIRONMENT <br /> Office of Environmental Protection PERMIT/SERVICES <br /> 25600 South Chrisman Road <br /> Tracy, California 95376-5000 <br /> Dear Mr. Cloud: <br /> REVIEW OF DRAFT WORKPLAN FOR WELL EVALUATION AND ABANDONMENT AT <br /> DEFENSE DISTRIBUTION REGION WEST (DDRW) , TRACY <br /> The Department of Toxic Substances Control (Department) has <br /> reviewed the subject draft workplan presented by Woodward Clyde. <br /> Our review has raised several issues which require clarification. <br /> Those issues follow in the body of this letter. <br /> 1) Section 4 . 5. 2 states that cement grout will be tremmied <br /> incrementally from the bottom of the boring to the surface. <br /> The Department is unclear what is meant by this statement. <br /> The statement as written, is too easily left to <br /> interpretation. Woodward Clyde 's intent needs to be <br /> clarified. <br /> Our recommendation would be to grout in stages of 150 to 200 <br /> feet., We further recommend the use of a packer to insure <br /> that the grout is delivered at a sufficient pressure to be <br /> invasive of the perforated casing. Special emphasis should <br /> be placed on using the Cocoran Clay Formation to seal the <br /> Upper Tulare Formation from the Lower Tulare Formation. <br /> 2) Section 4 . 1 outlines the procedures for drilling out the <br /> water supply wells. <br /> Regarding well no. 1, it is unclear if the 12 inch liner at <br /> the bottom of the well will be drilled out. Whether it is <br /> or is not may have an impact on the drilling and grouting <br /> processes. This point should be specified in the final <br /> workplan. <br /> 3) Section 4 . 5 states that a grout mixture of 7 sacks of <br /> Portland Type I-II cement will be used per gallon of water. <br /> The Department of Water Resources (DWR) bulletin 74-81 <br /> recommends that 4 1/2 to 6 1/2 gallons of water be used per <br /> UD <br />