|From:||Tony Chenhansa <email@example.com>|
|Date:||30 Oct 1998 16:37:27|
Original message From: Kitchingman.Kent@epamail.epa.gov Re: Bruce Klafter's question concerning the containment zone approach as a model. The CZ policy is so flexibile that using it as a model would be risky, i.e., you might agree with it's application in one situation and not another. The CZ approach is excellent in some situations, for example a South Bay site where a PRP built an adequate pump and treat system, operated it for years at significant expense, demonstrated decreasing mass removal that reached an asymptotic level for several years, turned off the system (with RWQCB permission) and demonstrated no change in contaminant levels (i.e. it did not increase), is required to continue monitoring, would have to turn the P&T on again if the plume threatens to migrate offsite (it's still beneath the PRPs property), no drinking water source is threatened (although this shallow "aquifer" is considered a drinking water source by the RWQCB). The above is a good model, combining the concepts of technical impracticability, natural attenuation, and cost/benefit. If I were a regulator I would not have a problem telling other PRPs they could get the same consideration if their situation was identical to the above. Of course, the regulator will encounter less compelling situations, for example: the PRP didn't install an adequate collection or treatment system, they didn't operate as long or as effectively as they should, they have inadequate data to demonstrate an asymptotic trend in mass removal, the plume is offsite and is threatening a usable aquifer, natural attenuation is supposedly but not demonstrated to be occuring, and probably most important, the misuse of cost/benefit analysis to terminate cleanups without making an adequate effort. In summary, the CZ designation can be a good alternative to an expensive and unproductive pump and treat, with no negative impact on human health or the environment. On the other hand, it could result in agencies being pressured to allow treatment systems to be shut down based on questionable data or through political processes. A good source for information on the CZ Policy is Steve Morse at the San Francisco Bay Regional Board, 510-622-2300.
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