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D.C. Municipal Regulations (Last Updated: September 13, 2017) |
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Title 21. WATER AND SANITATION |
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Chapter 21-11. WATER QUALITY STANDARDS |
Section 21-1106. SITE SPECIFIC STANDARDS
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1106.1 If requested, the Director may allow a person to conduct a site-specific study to change the numerical criteria when at least one (1) of the following conditions exists:
(a) The species, or endangered species, at the site are more or
less sensitive than those included in the national criteria data set; or
(b) Physical or chemical characteristics of the site alter the
biological availability or toxicity of the chemical.
1106.2 If the criteria in subsection 1104.8 are found to be unsuitable for the District waters based upon the conditions described in subsection 1106.1, when requested to do so, the Director may adopt site-specific criterion for Class C waters, except for mercury and selenium, or for Class D waters, only when a site-specific study necessitates.
1106.3 When requested to do so, based upon the conditions described in subsection 1106.1 and, if warranted, the Director shall allow site-specific studies to generate scientific information regarding:
(a) The Water Effect Ratio for metals specific to the District waters;
(b) The sensitivities of the aquatic organisms prevalent in the District;
(c) The toxicity of chemicals to the fish in the District waters and related human health effects; and
(c) Any other compelling factors that merit consideration for changing the numerical standards in subsection 1104.8.
1106.4 A person or persons planning to conduct a site-specific study shall submit a complete plan of study to the Director for approval, and the site-specific study shall be carried out only after the Director approves the study in writing, subject to the requirements set forth in this section.
1106.5 The Director shall provide advance notice to all discharge permittees and applicants for discharge permits prior to the initiation of any site-specific study.
1106.6 All site-specific studies and adoption of site-specific criteria shall be subject to the following requirements:
(a) Once the Director has approved the study, it shall be concluded in accordance with the approved plan;
(b) A person or persons conducting a site-specific study subject to subsection 1106.3 shall submit to the Director for review and approval all data, analyses, findings, reports, and other information the Director deems necessary;
(c) The Director shall seek review of the findings of the site-specific studies and other relevant information by the public, as well as by appropriate local and federal government agencies and consider their concerns before adopting any less stringent site-specific criterion based on those findings; and
(d) If the study concludes that a more stringent criterion is needed for Class C or D waters than provided in subsection 1104.8, then the Director shall modify the standards to reflect the more stringent level of protection.
1106.7 If a study is conducted to determine the Water Effect Ratio (WER) for metals and the criteria are in the dissolved form, the WER must be based on the dissolved fraction of the metals. If the study is conducted to determine the WER for metals and the criteria are in the total recoverable form, the WER must be based on the total recoverable fraction of the metals. If WERs are to be developed, EPA guidance Interim Guidance on Determination and Use of Water Effect Ratios for Metals, EPA-823-B-94-001, February 1994, shall be used and at a minimum, the following conditions shall be met unless the Director approves a deviation or alternate method:
(a) If a WER study concludes that an existing criterion is not stringent enough, then the criterion shall be made more stringent;
(b) At least two (2) sensitive indicator species, a fish and at least one (1) invertebrate, shall be used to determine toxicity in laboratory water and water collected from the site;
(c) The LC50 in the laboratory water must be comparable to the LC50 data developed by EPA;
(d) Water samples collected from the site shall be representative of critical low flow. A minimum of eight (8) samples per location per season shall be evaluated;
(e) Samples shall be taken at the edge of the mixing zone unless multiple discharges are involved. At least one (1) sample shall be reasonably well mixed with the flow of the receiving water, or the sample shall be well outside the regulatory mixing zone;
(f) Laboratory water shall be the same as the water used by EPA and adjusted for site water characteristics and hardness;
(g) The trace metal shall be added in the form of a highly soluble inorganic salt;
(h) The chemical and physical characteristics, both dissolved and total recoverable metal concentrations, hardness, pH, alkalinity, suspended solids, organic carbon, temperature, and specific metal binding ligands (where known to be important), and any other water quality characteristic that affects bioavailability and toxicity of the water should be monitored during the toxicity tests;
(i) A WER that is large or that is based on highly variable tests may be rejected;
(j) The WER shall be the geometric mean of the two (2) species; and
(k)All chemical, biochemical, biological, and other appropriate analyses shall be conducted using EPA-approved methods.
1106.8 If a site-specific study is conducted to determine the Class D Human Health Criteria and related human health effects, at a minimum, the study shall incorporate the following information:
(a) Bioconcentration factors of the substances in the commonly consumed fish in the District;
(b)Percent lipids in the commonly consumed fish in the District; and
(c) Information regarding the consumption by the public of fish caught from the District waters.
1106.9 The determination of subsection 1106.8 (a) and (b) shall be made using EPA-approved methods.
1106.10 The criteria, based upon a site-specific study and information collected through the study, shall be calculated using relations developed by EPA Technical Support Document for Water Quality-Based Toxics Control, EPA-505-2-90-001, March 1991, minus the component for drinking water, as follows:
(a)For noncarcinogens:
NEW CRITERIA = (RfD x WT)/(FC x L x FM x BCF)
where RfD is the reference dose from the EPA Integrated Risk Information System (IRIS) database, WT is seventy (70) kilograms, FC is the daily fish consumption by the exposed population in kilograms per day, L is the ratio of lipid fraction of fish tissue consumed to three percent (3%), FM is the food chain multiplier and BCF is the bioconcentration factor for fish with three percent (3%) lipid.
(b)For carcinogens:
NEW CRITERIA = (RL x WT)/(q1* x FC x L x FM x BCF)
where WT, FC, L, FM, and BCF are as stated above; RL is 10-6 and q1* is the carcinogenic potency factor from the EPA IRIS database.
1106.11 If the effluent limitation for a metal in a discharge permit is specified as "total recoverable", and the criterion for it in subsection 1104.8 is specified as "dissolved", either of the following two (2) approaches based on The Metals Translator: Guidance for Calculating a Total Recoverable Permit Limit From a Dissolved Criterion, EPA-823-B-96-007, June 1996, may be used, subject to prior review and approval by the Director:
(a) The criterion may be used as total recoverable for the purpose of establishing effluent limitations; or
(b) A site-specific ratio between the dissolved and total recoverable metal may be developed by systematic monitoring and analysis of the effluent and of the receiving water at the edge of the mixing zone during periods that reflect the environmental conditions upon which the permit was issued. This ratio shall incorporate considerations to avoid toxicity to aquatic organisms from deposition to the sediment outside of the mixing zone. The ratio of dissolved to total recoverable metal shall then be used to determine the total recoverable effluent limits based on the dissolved metal criterion.
1106.12 The Director may establish additional requirements for adopting site-specific water quality standards.