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Oklahoma Administrative Code (Last Updated: March 11, 2021) |
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TITLE 785. Oklahoma Water Resources Board |
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Chapter 46. Implementation of Oklahoma's Water Quality Standards |
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Subchapter 9. Implementation of Criteria to Protect the Agriculture Beneficial Use |
SECTION 785:46-9-5. Reasonable potential
Latest version.
- (a) General. The need for a permit limit will be determined on a mineral constituent basis, after application of the reasonable potential equation specified in (b) of this Section, which considers assimilation capacity of the receiving water and effluent variability.(b) Reasonable potential equation. OAC 785:45-5-13(d) requires that complete mixing of effluent and receiving water be taken into account in the reasonable potential equation. The use of mass balance to obtain wasteload allocations for complete mixing is codified at OAC 785:46-7-3(a). Therefore, the reasonable potential equation for mineral constituents is C = (QuBC + QeC95) / Qu + Qe), where C95 = 2.13 Cmean, where Cmean is the geometric mean of all effluent concentrations analyzed for the mineral. If the geometric mean cannot be determined, an arithmetic mean may be used. If sufficient effluent concentration observations exist as determined by the permitting authority, then the permitting authority may compute the 95th percentile concentration and use it as C95, in accordance with OAC 785:46-5-3(b)(1).(c) Reasonable potential to exceed yearly mean standard. Qu = A and Qe = Qel in OAC 785:46-9-5(b) to obtain a long term average concentration after complete mixing. If C is greater than the higher of the YMS or 700 milligrams per liter for TDS or 250 milligrams per liter for chlorides and sulfates, there is a reasonable potential to exceed an Agriculture beneficial use criterion, and a permit limit is required.(d) Reasonable potential to exceed sample standard. Qu =0.68A and Qe = Qes in OAC 785:46-9-5(b) to obtain a short term average concentration after complete mixing. If C is greater than the higher of the SS or 700 milligrams per liter for TDS or 250 milligrams per liter for chlorides and sulfates, there is a reasonable potential to exceed an Agriculture beneficial use criterion, and a permit limit is required.