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David Wang, P.E. , Chief <br /> SPECIFIC COMMENTS: <br /> Geologic Cross Se--tions/Pages 1-13 !Figure 1 . 3-1? !--1 - <br /> (Figure 1. 3-5) , 1-19 (Figure 1. 3-6) : These were not provided. <br /> Cross sections were provided in the earlier RI report <br /> (ESE November 1990) . The Department recommends that these be <br /> added or referenced. <br /> 6) Disposal Option/Pages 3-2 : The final selection of a disposal <br /> option was not included in the FFS. A disposal selection, <br /> approved by the regulatory agencies, needs to be made. <br /> 7) - Air Stripping Efficiency/Pages 4-14 : A general statement is <br /> made that two tower air strippers are the most efficient type. <br /> This statement does not take into account plume Eize, <br /> contaminant concentration, pumpage rate, or ground water f low. <br /> It is further discounted by the FFS ' s own recommendation to <br /> remove one tower from operation as the reductior in <br /> contamination makes its use unnecessary. It is recomme nded <br /> that this statement be rewritten to address and clarify these <br /> issues. <br /> 8) Water Sampling/Pages 4-20: The discussion of water sam ling <br /> includes only TCE. This would not be acceptable to the <br /> Department. An extensive (all contaminant parameters) <br /> performance monitoring program will have to be developed and <br /> approved by the regulatory agencies. <br /> 9) Pilot Studies/ Pages 4-22 and 5-19: Pilot studies for carbon <br /> adsorption and W light are recommended respectively. It has <br /> been the Department' s experience that pilot studies are not <br /> usually necessary for off the shelf technologies. The <br /> information that would be gained from a pilot study can <br /> usually be freely acquired from a vendor. If pilot studies <br /> were included in the cost estimates, they can probably be <br /> removed. This might make these technologies more attractive. <br /> 10) TCE Removal/Pages 5-32 Section 5. 6. 1: This section states <br /> that TCE is the only constituent addressed. The Department <br /> recognizes this statement and is concerned about it. Without <br /> a discussion on other constituents, ARARs or health effects <br /> cannot be fully evaluated. We recommend that other <br /> constituents be addressed prior to finalizing the FFS. <br /> 11) Distribution Coefficient (Kd) Calculation/Page R-1: The <br /> calculation indicates tricholorethane (TCA) was used to <br /> develop Kd, which was subsequently used in the modeling As <br /> TCE, and not TCA, was the only constituent discussed for the <br /> system design. The Department would like a clarification for <br /> this apparent inconsistency. <br />