Containment Zone

[Tony Chenhansa <tonyc@cpeo.org>]

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.