13    REGULATORY OPTIONS UNDER WATER QUALITY BASED
NATIONAL POLLUTANT DISCHARGE ELIMINATION
SYSTEM PERMITTING
Philip M. Simmons, Environmental Engineer
Tennessee Department of Health and Environment
150 Ninth Avenue North, Fourth Floor
Nashville, Tennessee 37247-3420
Robert G. O'Dette, Environmental Engineer
Tennessee Department of Health and Environment
150 Ninth Avenue North, Fourth Floor
Nashville, Tennessee 37247-3420
INTRODUCTION
Since the passage of the Federal Water Pollution Control Act (Clean Water Act, as amended) in
1972, it has been the goal of the federal government as interpreted by the Environmental Protection
Agency (EPA) to "restore and maintain the chemical, physical, and biological integrity of the Nation's
waters"1. In implementing this goal and the goal of toxic pollutant control as mandated by the Clean
Water Act of 1987, EPA and state water pollution control regulatory agencies have developed options
to be used by the permit issuing authority for the protection of water quality through the issuance of
National Pollutant Discharge Elimination System (NPDES) permits to dischargers to the nation's
waters. The purpose of this paper is to discuss these approaches: the chemical-specific approach to
water quality permitting and the whole-effluent approach to water quality permitting. Industrial and
municipal facilities that discharge to zero flow receiving streams will be particularly influenced by
these options.
THE CHEMICAL-SPECIFIC APPROACH
The chemical-specific approach to toxics control involves the use of laboratory-generated water
quality criteria or state standards to limit specific toxicants directly. The toxicity analysis of those
chemicals is done in a comprehensive testing program that, unlike whole-effluent testing, attempts to
consider a range of toxic endpoints including human health impact and bioaccumulation. Once a
criteria is developed, the number is applied, through an exposure analysis, as a permit limit to ensure
that the level of that toxicant is not exceeded after discharge. Fate modeling of the toxicant to estimate
its behavior after discharge can be an important step in establishing water quality-based permit
limits.
There are advantages and disadvantages to this approach. Advantages to this approach are: (1)
Treatment systems are more easily designed to meet chemical requirements because more treatability
data are available and treatment engineers and permit writers are more familiar with the procedures;
(2) The fate of a pollutant can be measured through modeling; (3) Chemical analyses, in simple cases,
can be less expensive than toxicity testing; and (4) Specific problem chemicals such as carcinogens or
bioaccumulative chemicals can be directly limited. Disadvantages to this approach are: (1) All toxicants in complex wastewaters may not be known and, therefore, control requirements for all potential
toxicants cannot be set; (2) It is not always clear which is the toxic compound(s) in the mixture; (3) It
can become expensive to measure individual toxicants, particularly where many are present in the
mixture. Organic chemicals can, in particular, be costly to measure; and (4) The bioavailability of the
toxicants at the discharge site are not assessed, and the interactions between toxicants (e.g., additivity,
antagonism) are not measured or accounted for.2
All waters in the nation have been classified for different uses that are either based on historical
record or anticipated uses. These uses are usually domestic water supply, industrial water supply, fish
and aquatic life, recreation, irrigation, livestock watering and wildlife, and navigation. Most waters
are classified for more than one use. Each classification has an ambient water quality criteria estab-
45th Purdue Industrial Waste Conference Proceedings, © 1991 Lewis Publishers, Inc., Chelsea, Michigan 48118.
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