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Mr. William Marshall <br /> October 20, 1988 <br /> Page 2 <br /> The closure plan has been approved by EPA. Attached (Enclosure 1) is the DHS <br /> Fact Sheet which describes the major points in regards to the history of WMU- <br /> A, a description of the closure plan, and the CEQA process followed. Enclosure <br /> 2 is the DHS completeness determination. <br /> The options listed in your letter have been investigated as follows: <br /> Option 1 - Remove the Waste <br /> This option would require the excavation, and removal of approximately 500,0001 <br /> cubic yards of hazardous material and cover. This material would require <br /> disposal at a Class I facility such as Cas alfa, Kettleman Hills or other out-of- <br /> state sites. Cost to excavate, haul, and dispose of this material is estimated at <br /> from $200 to $300 per cubic yard. Thus it would cost from $100 to $150 million <br /> dollars to remove the waste. This cost, in addition to the many environmental <br /> hazards that would be encountered would make this option infeasible. <br /> (Based on the area of trenches 1, 2 and 3, 600' x 500' x 40' deep and the <br /> area of trench 4, 200' x 300' x 30' deep.) <br /> Option 2 - Obtain a Variance for the Waste from DHS <br /> This option could be pursued with DHS but it is not likely that a variance would <br /> be granted since the waste was placed under a hazardous waste facilities permit <br /> and has been classified as hazardous. Additionally, such a variance would serve <br /> no purpose in protecting the environment. <br /> Option 3 - Retrofit WMU-A with an Engineered Alternative approved by the <br /> Regional Board. <br /> Under this option, it is proposed that the approved closure of WMU be <br /> considered by the Regional Board to meet the requirements of an engineered <br /> alternative. <br /> Details of the plan are described in documents previously submitted to the <br /> RWQCB and summarized in Enclosure 1. The design includes an impermeable <br /> cap to exclude future infiltration and is statically as well as dynamically stable <br /> under earthquake conditions. Quarterly monitoring well sampling has indicated <br /> no contamination down gradient of WMU-A. This sampling will continue in the <br /> existing wells and a new down gradient well will be installed in October, 1988. In <br /> addition to the monitoring wells, lysimeters will be installed under each sump of <br /> the 4 trenches under WMU in October, 1988. <br />