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2. The D zone has not been monitored adequately in some locations, notably the west end of the South Balloon, and the central part of the North Balloon. Local vertical gradients where onsite and offsite pumping wells are operating have not been adequately characterized, nor have the effects of stratigraphy on contaminant migration been adequately characterized. 3. Pg. 10-1. finding#2. "Based on relative moisture of sediments recovered during drilling and results of the seismic reflection survey, it appears that most of the sediments underlying SHAD are not saturated with water. It is estimated that only 25 percent of the subsurface materials are saturated with water. The saturated units are generally cleaner sands and represent potential flow paths for groundwater and contaminant movement." This statement is confusing. Does "subsurface" as used here include 'the vadose zone, which may include transiently saturated regions, or does it refer to the materials below the water table. Alluvial materials beneath the water table are normally considered to be saturated. What would account for unsaturated porosity beneath the water table? Has any attempt been made to determine whether or not low -perme- ability units are as contaminated as sandy units? 4. Pu. 10-1. finding #3. "Because the relative proportion of saturated sediments is low, the total quantity of potential contaminated groundwater is less than originally estimated." See Comment #1. Please explain the significance of this finding in terms of remedial actions. 5. Pg. 10-1. finding #4. "The aquifer system (i.e., aquifer and aquitards) can best be described as a non -steady-state, anisotropic, multiple, discontinuous, leaky artesian system." This is a very broad statement, applicable to nearly any aquifer system at some level of detail. What simplifying assumptions can or have been made to enable the system to be modeled? 4