SITE INFORMATION AND CORRESPONDENCE

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Jim Pinasco Page 7 August 1 , 1989 - Hydraulic conductivities derived from slug tests should be used with caution because the test may measure only the permeability of the filter pack and borehole wall of the well . The units in some of the columns are mislabeled. The table shows transmissivity as being gallons per day per square foot, and hydraulic conductivity as being gallons per day per foot. The hydraulic conductivity should have been reported in gallons per day per square foot, and transmissivity in gallons per day per foot. Comment 15 (Groundwater Flow Rates) On page 3-37, the Draft RI/FS states that the velocity of groundwater is estimated to be approximately 130 feet per year using a hydraulic conductivity of 30 feet per day. The estimate of groundwater velocity of 130 feet per year may be too low. Clarification is requested because using the hydraulic conductivity values from the constant discharge pumping tests, TSSU has calculated that the groundwater velocity ranges from 48 to 560 feet per year. Comment 16 The Draft RI/FS states the following on page 5-22 , paragraph 5. 3 . 3 . 3 : "The retardation factors for TCE and PCE (assuming a fractional organic carbon content of Upper Tulare HSU to be 0 . 005, bulk density of 1. 6 g/cc and Koc values of 250 and 42 , respectively) are 2 . 3 and 8 . 6 , respectively. Thus, TCE and PCE plumes are expected to move at about 50 ft/yr and 15 ft/yr, respectively. " TSSU interprets that the TCE and PCE may be moving at a higher velocity than quoted above due to possible higher groundwater velocities than those used in the above quotation. Comment 17 The well as-builts diagrams do not show centralizer locations on the monitoring well as-built diagrams. Centralizers should have been installed on the monitoring well casing and well screens to aid in keeping the casing and screen centered in the