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Mike Infurna [EH] From: Nuel Henderson [EH] Sent: Friday, July 07, 2006 10:08 AM To: 'Jim Barton' Cc: Margaret Lagorio [EH]; Mike Infurna [EH] Subject: RE: Flag City Chevron Jim, Thanks for the copy of the AGE response to the EHD comments. Although there is no need for EHD to respond formally, these are our'informal' comments. First, it is interesting that, like a skilled politician, the answers provided by AGE did not address the EHD questions, but some other questions. Essentially, the response seems to be (paraphrased)' we have abundant data, we spent a lot of money, more work will not be cost effective, we have models' without directly addressing the specific concerns raised by the EHD. The EHD concerns center on the behavior of the plume(s) in MW-8A and MW-2 and understanding the hydrogeological environment in which it occurs, and ultimately, its potential for impacting the CSA well(s). The EHD does not consider a model adequate if it fails to explain what appears to be significant plume behavior. One comment on the EHD letter of 18 May 2006, the EHD statement that the 'RWQCB should use a more cautious approach toward closing the FCC site' would have been better stated (somewhat paraphrased) as 'due to the circumstances noted, a higher degree of certainty regarding future behavior of the FCC (and other) plume(s) is warranted'. EHD does not consider it likely that the contaminants in MW-8A originated on the FCC site, the question is why the concentrations are persisting in the well while they have dropped off sharply in MW-19 and MW-20. This is a plume / hydrogeological question, and goes to model validation. The meaning of the contaminant concentration trends in MW-2 is not clear and EHD has not reviewed data acquired from that well since submitting the comment letter. At the time EHD submitted its comments the extraction wells had been sampled only once since turning off the system, data from which may have helped understand MW-2 trends. EHD perceived that the need was (and still is) to have a good understanding of the MW-2 trend and its import to the contaminant mass and the-hydrogeological environment in which it occurs. Again, model validation. In its four pages of response, AGE did not answer this question or explain how this trend occurs. If AGE has abundant data and valid models, they should be able to address these simple questions. -----Original Message----- From: Jim Barton [mailto:jbarton@waterboards.ca.gov] Sent: Thursday, July 06, 2006 9:39 AM To: Mike Infurna [EH]; Nuel Henderson [EH] Cc: Margaret Lagorio [EH] Subject: Fwd: Flag City Chevron FYI - paper copy to follow. Thanks Margaret. Jim James L.L. Barton, P.G. Engineering Geologist California Regional Water Quality Control Board Central Valley Region, 11020 Sun Center Drive, Suite 200, Rancho Cordova, CA 95670 office (916) 464-4615 t