Washington Administrative Code
Title 173 - Ecology, Department of (See also Titles 197, 317, 372, and 508)
Chapter 173-205 - Whole effluent toxicity testing and limits
Section 173-205-120 - Permit limit removed for attainment of a whole effluent toxicity performance standard
Universal Citation: WA Admin Code 173-205-120
Current through Register Vol. 24-06, March 15, 2024
(1) Whole effluent toxicity limits assigned pursuant to WAC 173-205-050(2) are eligible for removal upon permit renewal if:
(a) The permittee has demonstrated compliance
with the whole effluent toxicity performance standard associated with that
limit for a minimum of three consecutive test years following effluent
characterization or for an entire subsequent permit term; and
(b) The permittee has not made any changes
within the last three years which would otherwise require additional effluent
characterization pursuant to WAC
173-205-060.
(2) The department may condition the nonassignment of a whole effluent toxicity limit for a permittee that has attained a performance standard described in WAC 173-205-050(2)(a), or subsection (1) of this section on routine monitoring with a rapid screening test.
(a) Before making such condition, the
department shall consider the potential for treatment system upsets, control
equipment failures, spills, accidental releases to the wastewater system, and
any other event which could result in a toxic discharge.
(i) Chemical monitoring may be required to
assess increases in effluent toxicity if it:
(A) Can account for the potential sources of
toxicity; and
(B) Is associated
with water quality-based effluent limits or any other permit mechanism that
requires a response to increases in effluent toxicity.
(ii) Rapid screening tests shall be required
if the department determines there is the potential for an event at the
facility which could result in a toxic discharge that would otherwise go
unnoticed.
(b) Rapid
screening tests for acute toxicity shall be expected to have a maximum
mortality proportion of twenty hundredths in one hundred percent effluent.
(i) The mortality proportion shall be
calculated by subtracting the number of test organisms living in one hundred
percent effluent at the end of the test from the number of test organisms
living in the control and dividing the result by the number of test organisms
living in the control.
(ii) The one
hundred percent effluent test concentration and the control shall have equal
numbers of test organisms.
(c) Rapid screening tests for chronic
toxicity shall be expected to have no statistically significant difference in
response between the acute critical effluent concentration and the control
using the method in Appendix H of EPA/600/4-89/001 or an equivalent method
approved by the department. Rapid screening tests for chronic toxicity must
meet the chronic statistical power standard.
(d) Whenever a rapid screening test result
fails to achieve the standard of (b) or (c) of this subsection, the permittee
shall be required to immediately retest with all of the acute or chronic
toxicity tests used in the last permit with whole effluent toxicity
testing.
(e) The results of the
acute or chronic toxicity tests conducted in response to a rapid screening test
shall be evaluated by the department to determine the need for new whole
effluent toxicity characterization requirements in the next permit or the need
for immediate administrative orders to implement the regulatory process which
begins in WAC
173-205-090.
(f) All rapid screening tests shall be
performed by laboratories accredited by the department in accordance with
chapter 173-50 WAC.
Statutory Authority: Chapter 90.48 RCW and 40 C.F.R. 122.44. 93-20-110 (Order 91-54), § 173-205-120, filed 10/6/93, effective 11/6/93.
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