[CPEO-MEF] Natural Attenuation

[bmolnaa@earthtech.com]

A previous message regarding natural attenuation and NO ACTION stated..

""--From Marsden Chen

The subject came up a couple of weeks ago and as usual there were pros
and cons. Natural Attenuation has been boldly presented in the NCP by
the USEPA. CERCLA requires the EPA to address NO ACTION as one of the
alternatives in a Superfund ROD. Listed below are synonyms for NO ACTION
which were used in the early days of the push to use and sell this
"INNOVATIVE TECHNOLOGY"....""

Monitored natural attenuation should not be confused with a NO ACTION
alternative. The requirement for evaluating NO ACTION in the CERCLA
Feasibility process is to provide a baseline evaluation of the risk the site
poses to human health and the environment and to outline the regulatory and
technical requirements for clean up. If a feasibility study finds that the
NO ACTION alternative complies with the nine criteria for evaluating a
remedy provided in the NCP, then basically the site would pose no risk. This
is not a natural attenuation argument. This is a risk-based argument. 

Monitored natural attenuation requires action be taken. While the action may
not be aggressive, MNA must pass the same nine criteria of evaluation that
other remedies do. The EPA guidance documents are very explicit on how to
demonstrate that a site is a candidate for MNA. Among the requirements are
1) a stable or shrinking plume; 2) control or removal of additive source
material; and 3) demonstration that sensitive receptors are not at risk. At
many sites, the data necessary to demonstrate that these requirements are
being met along with the continued monitoring exceed the cost of
conventional remedies. 

Typically, MNA is not proposed as the sole remedy at a site. Once a source
removal remedy has been implemented, MNA may be proposed if it can be
demonstrated that it meets the technical requirements outlined in the NCP.
All of these decisions must be sent for public comment prior to issuance of
the ROD. While many feel that public comment on RI/FS type documents doesn't
pay dividends, I think that in many instances, community acceptance is the
driver for remedy selection. An active, well-informed community can
significantly effect a remedy at a Superfund site. Ensuring that the
technical aspects of a remedy have been evaluated in the FS  should be the
primary responsibility of the reviewing agency (EPA or their agent) however
an active community review can provide essential insight to the process. 

As for the other terms that were listed in the email, many are not
synonymous terms for natural attenuation or monitored natural attenuation. A
proposed remedy that uses a biological treatment component doesn't
necessarily imply it is a natural attenuation method. In many instances,
biological treatment methods involve very aggressive techniques.

I hadn't heard the term "Wink and Walk" before but it's quite amusing. My
response is that this term could be used to describe more than natural
attenuation arguments. Basically any remedy that proposes to do the minimum
"protective" work and is not fundamentally sound technically could be
labeled so. Our duty as concerned citizens is to make sure there are no
"wink and walk" remedies proposed by staying informed and active.
  
Barry Molnaa



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