Current through Register Vol. 24-06, March 15, 2024
(1)
Alternative discharge standards for trickling filters which were constructed
and/or expanded prior to November 1984 are:
(a) Up to a thirty-day average of 45 mg/L
BOD, 45 mg/L TSS. Seven-day averages shall not exceed 65 mg/L BOD, 65 mg/L TSS.
In addition, the thirty-day average percent removals of BOD and TSS shall not
be less than sixty-five percent of influent concentrations;
(b) Notwithstanding (a) of this subsection,
not any less stringent than "effluent concentrations consistently achievable
through proper operation and maintenance" of the wastewater facility based on
an analysis of the past performance, the design, and the design capacity of the
wastewater facility;
(c) Fecal
coliform and pH discharge standards are as established in WAC
173-221-040.
(2) Alternative discharge standards for waste
stabilization ponds which are the principal treatment process and which either
have less than a two million gallon per day design capacity or have received,
prior to the effective date of this regulation, the department's approval under
chapter 173-240 WAC, for a greater design capacity, are:
(a) Up to a thirty-day average of 45 mg/L
BOD, 45 mg/L TSS. Seven-day averages shall not exceed 65 mg/L BOD, 65 mg/L TSS.
Additionally, the thirty-day average percent BOD removal shall not be less than
sixty-five percent of influent concentrations.
(b) The discharge standards for TSS in (a) of
this subsection may be adjusted by the department to conform to the "TSS
concentrations achievable with waste stabilization ponds," provided that
operation and maintenance data indicate that the TSS values specified in (a) of
this subsection cannot be achieved.
(c) Notwithstanding (a) and (b) of this
subsection, not any less stringent than "effluent concentrations consistently
achievable through proper operation and maintenance" of the wastewater facility
based upon an analysis of the past performance.
(d) Fecal coliform and pH discharge standards
shall be as established in WAC
173-221-040.
(3) For domestic wastewater facilities which
receive flows from combined sewers, the department shall decide on a
case-by-case basis whether any attainable percent removal can be defined during
wet weather. If it can be defined, the department will set an alternative
percent removal effluent limitation for the wet weather period. A permittee who
requests such alternative limits shall submit supporting documentation to the
department.
(4)
(a) For domestic wastewater facilities which
receive less concentrated influent wastewater, permittees can request and
submit supporting documentation for:
(i) A
lower percent removal effluent limitation than the discharge standards set
forth in WAC
173-221-040, or subsections (1)
and (2) of this section; or
(ii) A
mass loading limit based upon the lower percent removal.
(b) To qualify for alternative effluent
limitations because of less concentrated influent wastewater, the permittee
must demonstrate:
(i) The wastewater facility
is consistently achieving, and/or will consistently achieve, the effluent
concentration limits and mass limits based upon the effluent concentrations in
its permit; and
(ii) That to meet
the percentage removal requirements set forth in WAC
173-221-040 or subsections (1)
and (2) of this section, the wastewater facility would have to achieve an
effluent concentration at least 5 mg/L below the effluent concentration which
is otherwise required; and
(iii)
The less concentrated influent is not the result of excessive infiltration
and/or inflow. The department will use federal regulations and guidance in
defining excessive infiltration and inflow; and
(iv) The development and implementation of a
program, subject to the department's approval, for ongoing wastewater facility
maintenance, repair, and replacement, including infiltration and inflow
control. A goal of the program shall be eventual achievement of the percent
removal requirements specified in WAC
173-221-040 and subsection (1) or
(2) of this section, whichever is applicable. The department shall incorporate
the approved infiltration and inflow control program into the permit for the
wastewater facility.
(5) Subject to the department's approval, a
request for alternative effluent limitations pursuant to subsections (1)
through (4) of this section must meet all of the following conditions:
(a) The effluent shall not cause water
quality violations; and
(b) The
permittee shall identify effluent concentrations consistently achievable
through proper operation and maintenance; and
(c) The permittee shall demonstrate that
industrial wastewater does not interfere with the domestic wastewater facility;
and
(d) The wastewater facility
must be within department approved hydraulic and organic design capacity;
and
(e) The permittee must complete
an analysis of whether seasonal alternative effluent limits are more
appropriate than year-round; and
(f) The wastewater facility must be able to
meet all other permit requirements and conditions.
(6)
(a) At
the option of the department, in lieu of the parameter BOD and the levels of
the BOD effluent quality specified in WAC
173-221-040, the parameter CBOD
may be substituted as an effluent limitation with the following levels of the
CBOD effluent quality provided: The thirty-day average shall not exceed 25
mg/L. The seven-day average shall not exceed 40 mg/L. Additionally, the
thirty-day average percent removal shall not be less than eighty-five percent
of the influent concentration.
(b)
At the option of the department, in lieu of the parameter BOD and the levels of
the BOD effluent quality specified in subsections (1) and (2) of this section,
the parameter CBOD may be substituted as an effluent limitation on a
case-by-case basis where data are available. The levels of CBOD effluent
quality shall not be less stringent than the following: The thirty-day average
shall not exceed 40 mg/L. The seven-day average shall not exceed 60 mg/L. The
thirty-day average percent removal shall not be less than sixty-five percent of
the influent concentration.
(c)
Permittee applications for substitution of CBOD for BOD under (b) of this
subsection shall include parallel CBOD and BOD data.
Statutory Authority:
RCW
90.48.035 and
90.48.260. 87-23-020 (Order
87-26), § 173-221-050, filed
11/12/87.