Potws and pretreatment

AuthorJeffrey G. Miller/Ann Powers/Nancy Long Elder/Karl S. Coplan
e Clean Water Act (CWA) regulates publicly owned treatment works
(POTWs) in much the same manner as it regulates other point sources. Dis-
charges of pollutants from POTWs are illegal unless they are authorized
by and in compliance with national pollutant discharge elimination system
(NPDES) permits. Permits for POTWs incorporate euent limitations
based on either technology-based standards or water quality-based standards,
whichever provides t he most stringent euent limitations. A lso, POTWs’
permit violations are subject to the sa me enforcement mechanisms as viola-
tions by other sources.
Yet the Act also regulates POT Ws dierently in many respects compared
to other point sources. POT Ws are subject to their own technology-based
standard—secondary treatment. Secondary treatment has its own set of vari-
ances. Statutory deadlines for POT Ws to achieve secondary treatment were
dierent than deadlines for other sources to achieve their technology-based
requirements. e construction of POTWs has been eligible for governmen-
tal funding, but the eligibility for such funding has itself subjected POTWs
to a host of other requirements, from conformance with regional plans to
compliance by their construction contractors with equal opportu nity hiring
programs. Moreover, POTWs receive the wastes of many industries (indirect
dischargers) and are expected to regulate discharges from these industries.
us POTWs have been a strange hybrid, as regulators a nd as members of
the regulated public.
e 1972 legislation required the U.S. Environmental Protection Agency
(EPA) to establish information on the degree of pollution reduction att ain-
able through secondary treatment. See CWA §304(d)(1). e legislative
history of the 1972 Amendments made it clear that secondary treatment
consisted of primary treatment (settling ) followed by biological treatment of
organic pollutants, for a pollution reduction of approximately 85% of both
suspended solids (SS) and biochemical oxygen demand (BOD). EPA dened
526 Water Pollution Control, 2d Edition
secondary treatment for BOD or SS to be a discharge of no more than 30
milligrams per liter (mg/L) for a 30-day average or 45 mg/L for a 7-day
average, and 85% removal for a 30-day average. 40 C.F.R. §133.102(a)-(b)
(2007). e 85% removal requirement not only reects legislative history,
but also prevents claiming attainment of the concentration-based limitations
through dilution by inltration of groundwater into sewer lines, a common
problem in POTW collection systems.
As enac ted in 1972, §301(b) followed the same process of progressively
more stringent treatment requirements for POTWs as it did for industrial
point sources (best practical technology (BPT ) followed by best available
technology (BAT)). See CWA § 301(b). For the rst level of treatment,
§301(b)(1)(B) required most POTWs to meet secondar y treatment require-
ments by July 1, 1977. For the second level of treatment, § 301(b)(2)(B)
required POT Ws to provide “the best practicable waste treatment technol-
ogy over the life of the works” by 1983. But POTW performance in attaining
secondary treatment was so disma l and expensive that the second require-
ment was deleted in 1981. Municipal Wastewater Treatment Construction
Grants Amendment of 1981, Pub. L. No. 97-117, § 21(b), 95 Stat. 1623,
e secondary treatment denition soon began to erode as a result of both
a desire to secure the greatest environmental benet from federal pollution
control expenditures and political pressure from localities seek ing to reduce
the cost of constructing POTWs. In the 1977 Amendments to the CWA,
Congress deemed “oxidation ponds, lagoons, and ditches and trickling l-
ters” to be “the equivalent of sec ondary treatment,” § 304(d)(4), although
they commonly do not provide 85% removal of BOD and SS or the low con-
centrations otherw ise required by EPA’s regulations. (Oxidation ponds and
lagoons are relatively cheap, but space-intensive treatment s ystems favored
by smaller communities where land is plentiful.) At the same time, Congress
authorized EPA to provide variances to secondary treatment requirements on
a ca se-by-case ba sis for POTWs discharging to marine waters where water
quality standards and other requirements were met and the POTWs provided
primary treatment (30% reduction of BOD and SS). See CWA §301(h).
EPA amended its regulations to dene the “equivalent of secondary treat-
ment” for oxidation ponds a nd the other specied types of facilities to be
45 mg/L of BOD and SS for a 30-day average, 65 mg/L for a 7-day average,
and 65% removal for a 30 -day average. 40 C.F.R. §133.105(a)-(b) (2007).
Moreover, it allowed states to further reduce the concentration limitations
POTWs and Pretreatment 527
to “conform to the BOD and SS euent concentrations consistently achiev-
able throug h proper operation and ma intenance . . . by t he media n (50th
percentile) facility in a representative sample of facilities” within the state.
40 C.F.R. §133.105(d). When EPA attempted similar relaxation of technol-
ogy-based standa rds for industry, environmentalists challenged the mea sure
as contrary to the CWA and courts agreed. See Natural Resources Defense
Council Inc. v. EPA, 790 F.2d 289, 16 ELR 20693 (3d Cir. 1986), reprinted
later in this chapter. At the same time, EPA erected formidable barriers for
POTWs seeking marine discharge variances. See 40 C.F.R. §125.57; Natu-
ral Resources Defense Council Inc. v. EPA, 656 F.2d 768, 11 ELR 20487 (D.C.
Cir. 1981). Why would it treat the rst set of variances leniently and the
second set grudgingly?
Finally, Congress provided extensions of time for POTWs to achieve sec-
ondary treatment, rst to 1983, and later to 1988. See CWA §301(i)(1). ese
extensions were given against a background of dismal POTW compliance
with the secondary treatment requirements in 1977. Whereas 81% of major
industrial permittees complied with BPT requirements by t he original July
1, 1977 compliance date, only 58% of major POTW permittees complied
with secondary treatment by that compliance date. Council on Environmental
Quality, Environmental Qualit y 1978, at 108, 110 (1978). Noncompliance
with euent limitations in permits by POTWs continued to be twice as high
for major POTWs compared to major industrial dischargers. In 1988, for
instance, 6-7% of major industrial permittees were in signicant noncom-
pliance, while 12-14% of major POT W permittees were in that category.
O  W, U.S. EPA, N W Q  I: 1988
R  C  156, tbl. 9-4 (1990) (EPA 440490003).
It should be noted that while secondary treatment is dened in terms
of BOD and SS, most POTW permits have euent limitations for fecal
coliform to meet water quality standards. Fecal coliform is treated by chlo-
rination or other disinfection methods, such as ultraviolet radiation. Many
permits have limitations on chlorine residual, i.e., the chlorine that rema ins
in the euent after use in the treatment of fecal coliform. ese limitations
usually contain both maximum and minimum concentrations: maximum to
protect aquatic organisms from the toxic eects of excess ch lorine and mini-
mum to make sure enough chlorine is used for d isinfection. Many POTW
permits also have limits on phosphorus and nitrogen as ammonia to control
algae blooms, hypoxia, and eutrophication.

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