[CPEO-MEF] Splitting the perchlorate problems in half

[Lenny Siegel <lsiegel@cpeo.org>]

The more I learn about perchlorate, the more I'm convinced that there
are two sets of perchlorate problems, not one. From a policy point of
view, perchlorate in drinking water is different than the perchlorate in
environmental media - soil, groundwater, and surface water - that
release the contaminant into drinking water.

Perchlorate is thus different, in most locations, than volatile organic
compounds (VOCs), such as trichloroethylene (TCE). At most VOC sites,
extraction pumps are turned off when the contaminant is found, not just
to block the exposure pathway, but to minimize the chemical's migration.
At some sites, water with low levels of contamination is blended with
water from other sources. Only at a few sites do people actually drink
treated (or even untreated) TCE-laden water. 

Our ability to detect perchlorate pollution, however, has outpaced our
ability to regulate it. Furthermore, in the three states (Nevada,
California, and Arizona) that drink water apparently contaminated by
perchlorate from the Las Vegas Wash, contamination is so overwhelming
that there is nothing else to drink.

While at most VOC sites we focus on the detection of, regulation of,
treatment of, and liability for contamination in the environment,
perchlorate raises issues both in the environment AND within water
distribution systems.

First and foremost, it's important to recognize that a health-based
standard for perchlorate ingestion means something different at the
point of drinking water delivery than when making remedial decisions. In
drinking water, the standard tends to be absolute. If pollution exceeds
the standard, we find other supplies, remove the contaminant, or as a
less desirable solution, blend in cleaner water to reduce the
concentration. For perchlorate, this means that water systems will be
installing treatment systems, regardless of how much cleanup is required upstream.

In cleanup the standard serves as a more flexible goal that guides risk
management decisions. The point of compliance may be far from the source
- at a property boundary, fox example. In selecting the remedy,
decision-makers may determine that excessive costs will prevent full
remediation to the health-based goal. Or as is often the case with TCE,
it may turn out that standard remedial technologies are incapable of
reducing contamination to the level of the standard. Even if achievable,
the goal may be decades away.

In my work with community groups, I tend to push for cleanups to achieve
stringent standards, but I recognize that risk management decisions are
more complex. This is particularly important in regulating the release
of perchlorate into the environment. While reasonable steps should be
taken to manage waste and substitutes should be developed to prevent its
generation, the establishment of a stringent health-based standard does
not mean that the use of perchlorate will never be permitted to deposit
localized concentrations above that standard.

The treatment strategy for drinking water may also be different. I've
recently viewed presentations arguing that bio-treatment tends to be
more effective and efficient than ion exchange. However, water vendors
who historically have gone to great expense to keep microbes out of
drinking water are reluctant to utilize any microbes, no matter how
benign, to treat their product. In remediation, however, public support
for active bioremediation tends to be strong.

It may also turn out that it is easier to sample for perchlorate in
drinking water supplies than in the environment. Both government and
industry scientists are now saying that the standard analytic method for
perchlorate detection generates false positives - that is, it finds
perchlorate where it isn't, or at least it reports inaccurately high
concentrations. As I understand it, this is largely due to interference
from other substances in the water. To the extent that drinking water
contains lower concentrations of other minerals, the measurements may be
more accurate.

Finally, at most environmental sites, the remedial response, including
treatment, is paid for by polluters and other responsible parties. In
the drinking water system, cleanup is paid for by water vendors. Unless
they can find a sugar daddy in Congress to help pay the bills, that cost
is passed on to the customers. Although they may have a case for cost
recovery - that is, to make polluters pay for the treatment system - at
most sites that is unlikely to occur until long after the expenses are made.

In no way am I suggesting that just by splitting the perchlorate problem
in half can we resolve the enormous challenge we face. Rather, I do
think, if we're careful to make the proper analytical distinctions, that
we should be better able to better comprehend the problems and negotiate
over solutions.


Lenny Siegel

-- 


Lenny Siegel
Director, Center for Public Environmental Oversight
c/o PSC, 278-A Hope St., Mountain View, CA 94041
Voice: 650/961-8918 or 650/969-1545
Fax: 650/961-8918
<lsiegel@cpeo.org>
http://www.cpeo.org

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