Environmental Engineering Reference
In-Depth Information
but the Clean Water Act is probably the best example of this system. Section
304 of the Clean Water Act requires the U.S. EPA, which administers the Act,
to research the effects of pollutants on the aquatic community and promulgate
water quality criteria. These criteria define the level of pollutants (e.g., metals,
pesticides) aquatic organisms or aquatic ecosystems can tolerate or the level of
essential characteristics (e.g., dissolved oxygen) necessary for the community to
thrive. These water quality criteria are based on decades of research evaluating
toxicity and species requirements for over a hundred different compounds on
dozens of different organisms, in numerous environmental settings. Section 303
of the Clean Water Act requires states to promulgate standards based on the
scientifically developed criteria, and in many cases, the toxicity tests and result-
ing water quality criteria developed by the U.S. EPA are adopted directly by
the individual states as enforceable standards. Sections 301, 302, and 402 of the
Clean Water Act establish the National Pollutant Discharge Elimination System
(NPDES) discharge permit program, which controls water pollution by regulat-
ing sources that discharge pollutants into waters of the United States.
Before Section 304 and State water quality standards were fully developed,
the NPDES permitting approach was to specify the level of wastewater treat-
ment necessary to protect the waters of the United States. For example, munici-
pal wastewater treatment systems were required to achieve a minimum of
secondary treatment (i.e., physical followed by biological treatment) with
specific discharge limits such as a maximum of 30 mg/l biochemical oxygen
demand or concentration of suspended solids. However, as the water qual-
ity necessary to protect aquatic life was defined, the reissued NPDES permits
became increasingly directed towards meeting the water quality criteria and
standards in the receiving waters. Thus discharges had to develop a combina-
tion of waste elimination and wastewater treatment processes such that once
the discharged treated effluent was mixed with the receiving waters, the water
quality standards were not exceeded.
Not all environmental approvals link the resource protection requirements
and approval so closely to scientific based research, but to some extent all
are based on resource protection. The basic philosophy behind environmen-
tal protection via permits and approvals is that an environmental resource
can withstand some degree of alteration without compromising the value,
service, sustainability, or other benefits provided by the resource. However,
once that level of alteration is exceeded, the resource can no longer remain
self-sustaining and provide the intended value and service. Thus a precursor
to any set of environmental permit requirements is to establish the acceptable
level of effect that will not compromise the sustainability of the resource, such
as the water quality standards required under the Clean Water Act. These
are then incorporated into the NPDES permit issued under the same act to
achieve the desired protection of the resource.
Frequently a piece of environmental protection legislation (including the
Acts discussed above) is directed at protecting a single environmental resource.
Under the legislative umbrella there can be many approvals and permitting
Search WWH ::
Custom Search