Okla. Admin. Code § 785:30-15-5

Current through Vol. 42, No. 4, November 1, 2024

Section 785:30-15-5 - Augmentation

(a)Stream augmentation.

(1) A mine operator may claim credit for one hundred percent (100%) of the amount of water it discharges to a stream emanating from a Sensitive Basin during a time of low flow that is less than or equal to the 50% exceedance listed by the USGS within the watershed where the mine is located. If the receiving stream or watershed is ungaged or does not have calculated median flow data available, the Board will utilize the USGS StreamStats extrapolation model or other method to calculate the 50% exceedance.

(2) The Board will review the 50% exceedance for gaged streams within the watershed on an annual basis.

(3) A mine operator shall monitor the flow conditions at the designated stream gage in order to determine whether and when stream augmentation credit can be obtained. The flows, dates and volumes of water discharged to a stream for augmentation credit shall be identified by the mine operator in the quarterly and annual reports required by 82 O.S. § 1020.2(E)(1).

(4) There shall be no credit for any water discharged to streams when the unaugmented flow is greater than the 50% exceedance.

(b)Groundwater augmentation.

(1) A mine operator may claim credit for one hundred percent (100%) of the amount of water that is placed in a groundwater augmentation basin that meets the requirements of this Section, less any water diverted from such basin.

(2) To qualify for credit, the mine operator must satisfy the following:

(A) The operator shall make a one-time water balance demonstration to the satisfaction of the Board that recharge from the subject groundwater augmentation basin exceeds evaporation. Once such a demonstration has been made, no accounting for evaporation or vegetative losses will be required. If a material change is made to the groundwater augmentation basin, a new demonstration shall be made for the changed basin.

(B) Each groundwater augmentation basin shall have a staff gage or other measuring device at least as accurate installed such that the gage registers the lowest water level in the basin. The staff gage or other appropriate device must be readable from a readily accessible location adjacent to the basin.

(3) No specific design or maintenance requirements need be followed for dedicated recharge structures provided that they shall not be filled by pumping to such a level that they overflow.

(4) The amount of water recharged to the aquifer from a groundwater augmentation basin shall be calculated on a mass balance basis. The applicable equation is: GWa = Ba * [(h1 - h2) - (E * 0.7)] + (I - O), where:

(A) GWa is the volume of water exiting the bottom and sides of the augmentation basin;

(B) Ba is the surface area of the augmentation basin (assumes vertical sides);

(C) h1 is the elevation of the water level in the basin at the beginning of the applicable time period determined using the installed staff gage;

(D) h2 is the elevation of the water level in the basin at the end of the applicable time period;

(E) 0.7 is the lake evaporation coefficient applied to pan evaporation;

(F) E is the calculated pan evaporation rate determined at the nearest Mesonet station determined as the sum of daily values for the applicable time period;

(G) I is the total inflow volume of water to the basin (it may be zero (0)) from all sources (including rainfall) for the applicable time period determined by measurement or reasonable estimation; and

(H) O is the total outflow volume of water from the basin (it may be zero (0)) by all pathways except evaporation for the applicable time period determined by measurement or reasonable estimation.

(c)Applications of augmentation credit.

(1) Credit obtained from augmentation of stream water or groundwater or both may be used by the mine operator to reduce or offset the amount of consumptive use of pit water by the operator that exceeds the MEPS.

(2) Credit obtained from augmentation of stream water or groundwater shall not be considered in the amount used pursuant to any permit to use stream water or groundwater that the mine operator may have; provided, the taking, use or disposal of pit water for stream augmentation pursuant to a Management Plan prepared in consultation with the Board may be claimed in an annual report of stream water use in order to avoid forfeiture of a right to use stream water held by the owner or operator of the mine.

Okla. Admin. Code § 785:30-15-5

Added at 30 Ok Reg 884, eff 6-13-13