| (a) Discharges into effluent limited segments.
(1) All discharges into effluent limited segments shall,
at a minimum, achieve secondary treatment. An effluent limited segment
is any segment which is presently meeting or will meet applicable
water quality criteria following incorporation of secondary treatment
for domestic sewage treatment plants and/or best practicable treatment
for industries.
(2) New or increased discharges into effluent limited
segments shall achieve that level of treatment deemed necessary by
the commission, based on the assimilative capacity and uses of the
receiving stream.
(b) Discharges into water quality impaired segments.
(1) All discharges into water quality impaired segments
for which evaluations have been developed shall, at a minimum, achieve
the treatment level specified in the recommendations of the evaluation
for that discharge. An impaired segment is a surface water segment
classified by the commission as water quality limited where conventional
treatment of wastewater discharged to the segment is not stringent
enough for the segment to meet applicable water quality standards;
monitoring data have shown significant violations of water quality
standards; advanced waste treatment for point sources is required
to protect existing exceptional water quality; or the segment is a
public domestic water supply reservoir used to supply drinking water.
(2) Discharges into water quality impaired segments
for which wasteload evaluations or total maximum daily loads have
not been developed shall, at a minimum, achieve secondary treatment
as provided by §309.1 of this title (relating to Scope and Applicability).
(c) Discharges into certain reservoirs. Any discharge
made within five miles upstream of a reservoir or lake which is subject
to on-site/private sewage facility regulation adopted under Texas
Water Code, Chapter 26 or Texas Civil Statutes, Article 4477-7e, or
which may be used as a source for public drinking water supply shall
achieve, at a minimum, Effluent Set 2 in §309.4 of this title
(relating to Table 1, Effluent Limitations for Domestic Wastewater
Treatment Plants). Five miles shall be measured in stream miles from
the normal conservation pool elevation. The commission may grant exceptions
to this requirement where it can be demonstrated that the exception
would not adversely impact water quality.
(d) Discharges from stabilization ponds. Effluent Set
3 in §309.4 of this title shall apply to stabilization pond facilities
in which stabilization ponds are the primary process used for secondary
treatment and in which the ponds have been designed and constructed
in accordance with applicable design criteria. Effluent Set 3 in §309.4
of this title is considered equivalent to secondary treatment for
stabilization pond systems.
(e) Discharge to an evaporation pond. Effluent discharged
to evaporation ponds must receive, at a minimum, primary treatment,
be within the pH limits of 6.0 - 9.0 standard units, and have a quality
of 100 milligrams per liter (mg/l) five-day biochemical oxygen demand
or less on a grab sample. For the purpose of this subsection, primary
treatment means solids separation which is typically accomplished
by primary clarifiers, Imhoff tanks, facultative lagoons, septic tanks,
and other such units.
(f) Land application of treated effluent. The commission
may authorize land application of treated effluent when the applicant
demonstrates that the quality of water in the state will not be adversely
affected. Each project must be consistent with laws relating to water
rights. The primary purpose of such a project must be to dispose of
treated effluent and/or to further enhance the quality of effluent
prior to discharge. For the purpose of this subsection, primary treatment
means solids separation which is typically accomplished by primary
clarifiers, Imhoff tanks, facultative lagoons, septic tanks, and other
such units.
(1) When irrigation systems ultimately dispose of effluent
on land to which the public has access, Effluent Set 4 in §309.4
of this title, at a minimum, shall apply. The pH shall be within the
limits of 6.0 - 9.0 standard units unless a specific variance is provided
in the permit based upon site-specific conditions. When irrigation
systems ultimately dispose of effluent on land to which the public
does not have access, the effluent must, at a minimum, receive primary
treatment and Effluent Set 5 in §309.4 of this title, at a minimum,
shall apply and the pH shall be within the limits of 6.0 - 9.0 standard
units unless a specific variance is provided in the permit based upon
site-specific conditions. Effluent may be used for irrigation only
when consistent with Subchapters B and C of this chapter (relating
to Location Standards and Land Application of Sewage Effluent).
(2) When overland flow systems are utilized for effluent
treatment, the public shall not have access to the treatment area.
(A) For land application permits, primary treated effluent
meeting Effluent Set 6 in §309.4 of this title, within the pH
limits of 6.0 - 9.0 standard units may be used consistent with environmental
safeguards and protection of water in the state.
(B) For discharge permits, at a minimum, Effluent Set
1 in §309.4 of this title shall apply to discharges from overland
flow facilities except where more stringent treatment levels are required
to meet water quality standards.
(3) When evapotranspiration beds, low pressure dosing,
or similar soil absorption systems are utilized for on-site land application,
the effluent shall, at a minimum, receive primary treatment and meet
Effluent Set 7 in §309.4 of this title. Use of these on-site
systems shall be consistent with environmental safeguards and the
protection of water in the state.
(4) When subsurface area drip dispersal systems, or
similar soil absorption systems ultimately dispose of effluent on
land where there is the significant potential for public contact,
as defined in §222.5 of this title (relating to Definitions),
Effluent Set 4 in §309.4 of this title, at a minimum, shall apply.
The pH shall be within the limits of 6.0 - 9.0 standard units unless
a specific variance is provided in the permit based upon site-specific
conditions.
(5) When subsurface area drip dispersal systems, or
similar soil absorption systems ultimately dispose of effluent on
land where there is the minimal potential for public contact, as defined
in §222.5 of this title, Effluent Set 5 in §309.4 of this
title, at a minimum, shall apply. The pH shall be within the limits
of 6.0 - 9.0 standard units unless a specific variance is provided
in the permit based upon site-specific conditions.
(6) Treated effluent may be land applied only when
consistent with Subchapters B and C of this chapter. Use of subsurface
area drip dispersal systems shall be consistent with environmental
safeguards and the protection of water in the state.
(g) Disinfection.
(1) Except as provided in this subsection, disinfection
in a manner conducive to the protection of both public health and
aquatic life shall be achieved on all domestic wastewater which discharges
into water in the state. Any appropriate process may be considered
and approved on a case-by-case basis.
(2) Where chlorination is utilized, any combination
of detention time and chlorine residual where the product of chlorine
(mg/l) X Time (minutes) equals or exceeds 20 is satisfactory provided
that the minimum detention time is at least 20 minutes and the minimum
residual is at least 0.5 mg/l. The maximum chlorine residual in any
discharge shall in no event be greater than four mg/l per grab sample,
or that is necessary to protect aquatic life.
(3) On a case-by-case basis, the commission will allow
chlorination or disinfection alternatives to the specific criteria
of time and detention described in paragraph (2) of this subsection
that achieve equivalent water quality protection. These alternatives
will be considered and their performance standards determined based
upon supporting data submitted in an engineering report, prepared
and sealed by a licensed Texas professional engineer. The report should
include supporting data, performance data, or field tracer studies,
as appropriate. The commission will establish effluent limitations
as necessary to verify disinfection is adequate, including chlorine
residual testing, other chemical testing, and bacteria testing as
specified in subsection (h) or (i) of this section.
(4) Except as provided in this subsection, disinfection
of domestic wastewater which is discharged by means of land application
or evaporation pond shall be reviewed on a case-by-case basis to determine
the need for disinfection. All effluent discharged to land to which
the public has access must be disinfected and if the effluent is to
be transferred to a holding pond or tank, the effluent shall be rechlorinated
to a trace chlorine residual at the point of irrigation application.
All effluent discharged to land via a subsurface area drip dispersal
system to which there is a potential for public contact shall be disinfected
and shall comply with an Escherichia coli
(E. coli) bacteria effluent limitation of 126 colony forming
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