SITE INFORMATION AND CORRESPONDENCE

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Frank Dellechaie Page 4 January 24, 1989 The contractors provided the following start dates for key events: February 6, 1989, Soil Gas Survey; February 20, 1989, Drilling of Exploration Boreholes; and March 6, 1989, Drilling Shallow Monitor Wells. The discussion shifted to the facility Closure Plan. DHS brought to the attention of the Contractors that the Draft Groundwater Assessment Plan states "Hargis + Associates, Inc. was retained in September 1988 to prepare and implement a Groundwater Assessment Plan, a groundwater monitoring program, and an approved Closure Plan for all solid waste management units. " The Contractors were asked if they intended to use the Closure Plan developed by SNR in March 1988, or develop a new plan. They indicated that it was their intention to go with the submitted plan. DHS then proceeded to discuss the most notable deficiencies of the current Closure Plan. 1. The current plan calls for stabilizing the sludges (three inches deep) and the top three inches of soil in place by adding "Quick Lime" to Pond 1, and sodium hypochlorite, or calcium hypochlorite to Ponds 1 and 2 . This treatment will raise the pH of the acidic soil in Pond 1 to approximately 10, neutralizing the soil and producing insoluble hydroxides; reduce the permeability and increase the strength of the treated material; and destroy any cyanide that may be present in the treated material. The stabilized material is to be moved to Pond 1, and if necessary to the southern portion of Pond 2 . Then Pond 1, Pond 2 , and the TCA disposal area are to be filled to the membrane elevation area with clean on-site or off-site soil. A Moisture Barrier and Cap consisting of a 30 mil thick membrane, a clean 12-inch sand layer, a six-inch aggregate base layer, and a four inch asphalt concrete surface will then be installed. There appear to be three general problems with this approach. (A) . First, Pond 1 and Pond 2 are not man-made surface impoundments. They are slight topographic depressions. The northern portion of Pond 1 contains a small forest, with a couple of large trees and extensive shrubs, bushes, and other plant life. The current Closure Plan does not address the removal and disposal of this greenery. Nor does it address the root system in this area. This problem needs to be addressed in the Closure Plan. (B) . The Closure Plan calls for the combining of the sludges and the top three inches of soil in the Pond 1 drainage area and Pond 2 area into Pond 1, and possibly the southern portion of Pond 2 . Pond 1 is extremely small, 25 feet in diameter and four feet deep, and does not appear to be nearly large enough to hold all this