SITE INFORMATION AND CORRESPONDENCE

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15) Page 7-12/Section 7. 3 .2 . 3 .2 : The discussion evaluates the effects of mounding from re-injection wells. The section should also evaluate the mounding effects expected from ponding of the effluent. 16) Page 7-12/Section 7. 3 .2 .4 : The vapor emission system for the air stripper is discussed, however, there is no discussion of the method for regeneration of the granular activated carbon units. The method and steps for carbon regeneration should be incorporated into the ROD. 17) Page 7-17/Section 7.4 .2 . 3 . 1: The evaluation of in situ biological treatment of sorbet contaminants is shown to have a negligible impact on the overall remediation at DDRW, Tracy. The Department recommends that it be re-evaluated in the site wide RI/FS if the technology continues to advance. 18) Page 8-1/Section 8 . 2 . 1: The use of in situ biological treatment for Alternative Number 4 is stated to be more effective then Alternative Number 3 which does not incorporate the biological treatment. However, Alternative Number 3 was chosen to be the most effective alternative. considering the choice of Alternative Number 3 , it appears to be inconsistent to claim that Alternative Number 4 is more effective. The inconsistencies in the discussion of Alternatives Numbers 3 and 4 need to be resolved. 19) Page 9-2/Section 9. 1. 1. 3 . 1: The discussion of ground water disposal should include an option to dispose of the treated effluent via ponds. 20) Page 9-3/Section 9. 1.2 .2. 1: To assure compliance with ARARs, it is recommended that a conference call be set up with the appropriate legal counsels to discuss and agree on the specific ARARs for OU - 1. if this proves to infeasible to accomplish, an effluent to assure regulatory agencies' and facility satisfaction should be proposed. -4-