At the International Erosion Control Association’s conference
last week in Reno last week, a group of people got together to discuss EPA’s
proposed Effluent Limitations Guidelines. Representing both the regulators and
the regulated, the group included Jesse Pritts of USEPA, Eric Berntsen of the
California State Water Resources Control Board, Cory Taylor of Beazer Homes USA,
and Robert Patterson of Pulte Home Corporation. I summarized some of their
comments, particularly those on the costs of implementing the proposed
guidelines, here. But one point that came up deserves from
further attention from stormwater managers.
For some construction sites in
some areas of the country, the guidelines propose a numeric effluent limitation
of 13 nephelometric
turbidity
units (NTUs). To
achieve this, EPA says, it will probably be necessary to use an advanced
treatment system, such as chitosan-enhanced filtration treatment, polymer
clarification, or electrocoagulation. During last week’s discussion, Robert
Patterson questioned what sort of certification would be in place, if any, for
people operating such systems, suggesting that concentrated chitosan released to
a water body would be toxic and would result in a fish kill. Some states have
banned other types of flocculants, and chitosan was therefore the main one he
considered in his analysis of the costs of implementing the guidelines.
This is the passage from EPA’s
proposal that addresses the potential risk:
“It has been suggested that, while operating active treatmentsystems that use polymers to reduce the turbidity of stormwater,construction site dischargers may overuse polymers and, in doing so,introduce toxicity or cause other adverse effects. EPA believes toxiceffects from discharges treated to meet a turbidity limit should not beoccurring and such events would be indicative of a poorly operatedtreatment system. Polymers are widely used at a variety of wastewatertreatment systems and facilities throughout the country, and EPA is notaware of any studies indicating that polymer addition to treatstormwater from construction sites using ATS has been found to pose asignificant risk to water quality at those facilities. There are ampleregulatory (i.e., enforcement actions) and financial (e.g., chemicalcosts) disincentives for dischargers to willfully overuse polymers intheir treatment systems. In addition, vendors have indicated thatdosages of polymers are carefully metered in ATS systems. Upon closerreview of the matter, it appears that this concern has been raised dueto anecdotal suggestions, rather than documented evidence of actualdischarge events causing toxic effects. To date, EPA has not identifiedany documented cases where the use of a polymer to treat C&D stormwater discharges caused
an adverse effect in the receiving waters.”
(You can read the entire proposal as
it appeared in the Federal Register here).
The counterargument goes something like this: As more and more sites than
ever before begin to use advanced treatment systems, inevitably some systems
will be handled by poorly trained operators, and accidents will be more likely;
just because EPA is not aware of significant risks in the past doesn’t mean
there won’t be more and greater problems in the future.
What is your experience with such systems, and what sort of safeguards do
you think should be in place if the guidelines are approved? Do we need more
detailed toxicity studies? Guidelines for operators of advanced treatment
systems? An actual certification program?