SECTION 252:606-5-2. Technology-based methodologies

  Technology-based methodologies include:

(1)   Industrial permits. Effluent limitation guidelines for industry categories and pollutants are promulgated by the EPA pursuant to the Federal Water Pollution Control Act, as amended by the Clean Water Act of 1977 and Water Quality Act of 1987. EPA guidelines are adopted and incorporated by reference in 252:606-1-5. If there are no industry category or pollutant guidelines applicable to the applicant's industry, BPJ of the permit writer applies.

(2)   Municipal permits.

(A)   Technology-based limitations for municipal discharges are based upon the definition of "secondary treatment". The Oklahoma definition of "secondary treatment" is more stringent than the EPA definition under 40 CFR Part 133. Subparagraphs (B) through (G) of this paragraph contain the EPA approved definition of "secondary treatment" for the State of Oklahoma, which is used in the development of wasteload allocations in the municipal point source inventory.

(B)   For facilities discharging to perennial streams, "secondary treatment" is defined as:

(i)   A monthly average of 30 mg/l Biochemical Oxygen Demand - 5 day (BOD5). A Carbonaceous Biochemical Oxygen Demand - 5 Day (CBOD5) of 25 mg/l is considered to be equivalent to a BOD5 of 30 mg/l.

(ii)   A weekly average of 45 mg/l BOD5. A CBOD5 of 40 mg/l is considered to be equivalent to a BOD5 of 45 mg/l.

(iii)   The monthly average percent removal for BOD5 or CBOD5 cannot be less than 85%.

(iv)   A monthly average of 30 mg/l total suspended solids (TSS).

(v)   A weekly average of 45 mg/l TSS.

(vi)   The monthly average percent removal for TSS cannot be less than 85%.

(vii)   The pH must be maintained between the limits of 6.5 and 9.0 standard units.

(C)   For discharges to intermittent streams (those with 7-day, 2-year, low flow of zero) and for any discharge to a lake as defined in this Section, secondary treatment is defined as:

(i)   A monthly average of 20 mg/l BOD5. A CBOD5 of 18 mg/l is considered to be equivalent to a BOD5 of 20 mg/l.

(ii)   A weekly average of 30 mg/l BOD5. A CBOD5 of 25 mg/l is considered to be equivalent to a BOD5 of 30 mg/l.

(iii)   The monthly average percent removal for BOD5 or CBOD5 cannot be less than 85%.

(iv)   A monthly average of 30 mg/l TSS.

(v)   A weekly average of 45 mg/l TSS.

(vi)   The monthly average percent removal for TSS cannot be less than 85%.

(vii)   The pH must be maintained between the limits of 6.5 and 9.0 standard units.

(D)   For discharges where treatment is solely provided by lagoons, whether the discharge is to a perennial or an intermittent stream, secondary treatment is defined as:

(i)   A monthly average of 30 mg/l BOD5. A CBOD5 of 25 mg/l is considered to be equivalent to a BOD5 of 30 mg/l.

(ii)   A weekly average of 45 mg/l BOD5. A CBOD5 of 40 mg/l is considered to be equivalent to a BOD5 of 45 mg/l.

(iii)   The monthly average percent removal for BOD5 or CBOD5 cannot be less than 65%.

(iv)   A monthly average of 90 mg/l TSS.

(v)   A weekly average of 135 mg/l TSS.

(vi)   The pH must be maintained between the limits of 6.5 and 9.0 standard units.

(vii)   Subparagraph (D) does not apply to a discharge to a lake as defined in this Section.

(E)   For purposes of this Section, a discharge to a lake is any discharge from a point source which is either a direct discharge into a lake, or within 5 river miles upstream of the conservation pool of any lake.

(F)   For purposes of this Section, a lake is an impoundment of the waters of the state which exceeds 50 acre-feet in volume which:

(i)   is owned or operated by a unit of government,

(ii)   appears in Oklahoma's Clean Lakes Inventory, or

(iii)   is a privately-owned lake which has beneficial uses similar to those of publicly-owned or operated lakes.

(G)   For purposes of this Section, percent removal is a percentage expression of the removal efficiency across a treatment plant for a given pollutant parameter, as determined from the monthly average values of the raw wastewater influent pollutant concentrations to the facility and the monthly average values of the effluent pollutant concentrations for a given time period.

(3)   Municipal treatment greater than secondary. In the CWA Section 208 "Water Quality Management Plan for Oklahoma," Appendix B, the only specific wasteload allocation numbers assigned are those that apply to facilities showing a need for treatment greater than secondary (e.g., 10 mg/l BOD5, 15 mg/l TSS, and 2 mg/l NH3-N). All other facilities receive an allocation of secondary.

(4)   Municipal secondary treatment. In the CWA Section 208 "Water Quality Management Plan for Oklahoma," Appendix B, determination of the actual effluent limits for a facility with an allocation of secondary can be accomplished by finding the stream class (perennial or intermittent) and the current treatment process (mechanical plant or lagoon, etc.). For example, an activated sludge facility (mechanical plant) that discharges into a perennial stream will have effluent limits of 30 mg/l BOD5 and 30 mg/l TSS as found in paragraph (2) of this Section.

(5)   Municipal bacterial limits. The Executive Director may establish in discharge permits limitations for bacteria where:

(A)   the proposed discharge is a "discharge to a lake" as defined in this Section, or

(B)   the proposed discharge may otherwise adversely affect the beneficial uses of the waters of the state.

[Source: Added at 21 Ok Reg 1584, eff 6-11-04; Amended at 31 Ok Reg 1297, eff 9-12-14; Amended at 32 Ok Reg 977, eff 9-15-15]