SECTION 460:20-45-10. Diversions

(a)   General requirements.

(1)   With the approval of the Department any flow from mined areas abandoned before May 3, 1978, and any flow from undisturbed areas or reclaimed areas, after meeting the criteria of Section 460:20-45-12 for siltation structure removal, may be diverted from disturbed areas by means of temporary or permanent diversions. All diversions shall be designed to minimize adverse impacts to the hydrologic balance within the permit and adjacent areas, to prevent material damage outside the permit area and to assure the safety of the public. Diversions shall not be used to divert water into underground mines without approval of the Department in accordance with Section 460:20-45-8(h).

(2)   The diversion and its appurtenant structures shall be designed, located, constructed, and maintained to:

(A)   Be stable;

(B)   Provide protection against flooding and resultant damage to life and property;

(C)   Prevent, to the extent possible using the best technology currently available, additional contributions of suspended solids to stream-flow outside the permit area; and

(D)   Comply with all applicable local, State, and Federal laws and regulations.

(3)   Temporary diversions shall be removed when no longer needed to achieve the purpose for which they were authorized. The land disturbed by the removal process shall be restored in accordance with this Subchapter. Before diversions are removed, downstream water-treatment facilities previously protected by the diversion shall be modified or removed, as necessary, to prevent overtopping or failure of the facilities. This requirement shall not relieve the operator from maintaining water-treatment facilities as otherwise required. A permanent diversion or a stream channel reclaimed after the removal of a temporary diversion shall be designed and constructed so as to restore or approximate the premining characteristics of the original stream channel including the natural riparian vegetation to promote the recovery and the enhancement of the aquatic habitat.

(4)   Temporary diversions shall be constructed to pass safely the peak runoff from a precipitation event with a 2-year, 6-hour recurrence interval or a larger event as specified by the Department.

(b)   Diversion of perennial and intermittent streams.

(1)   Diversion of perennial and intermittent streams within the permit area may be approved by the Department after making the finding relating to stream buffer zones called for in Section 460:20-45-16 that the diversions will notadversely affect the water quantity and quality and related environmental resources of the stream.

(2)   The design capacity of channels for temporary and permanent stream channel diversions shall be at least equal to the capacity of the unmodified stream channel immediately upstream and downstream from the diversion.

(3)   The requirements of Paragraph (a) (2) (B) of this Section shall be met when the temporary and permanent diversions for perennial and intermittent streams are designed so that the combination of channel, bank and flood-plain configuration is adequate to pass safely the peak runoff of a 10-year, 6-hour precipitation event for a temporary diversion and a 100-year, 6-hour precipitation event for a permanent diversion.

(4)   The design and construction of all stream channel diversions of perennial and intermittent streams shall be certified by a qualified registered professional engineer as meeting the performance standards of this Subchapter and any design criteria set by the Department.

(5)   Flow from perennial and intermittent streams within the permit area may be diverted, if the diversions:

(A)   Are approved by the Department after making the findings cared for in Section 460:20-43-16(a);

(B)   Comply with other requirements of this Subchapter; and

(C)   Comply with local, State, and Federal statutes and regulations.

(6)   When stream-flow is allowed to be diverted, the stream channel diversion shall be designed, constructed, and removed, in accordance with the following:

(A)   The longitudinal profile of the stream, the channel and the flood-plain shall be designed and constructed to remain stable and to prevent to the extent possible using the best technology currently available, additional contributions of suspended solids to stream-flow or to runoff outside the permit area. These contributions shall not be in excess of requirements of State or Federal law. Erosion control structures such as channel lining structures, retention basins, and artificial channel roughness structures shall be approved for permanent diversions only where they are stable and will require infrequent maintenance;

(B)   The combination of channel bank and flood-plain configurations shall be adequate to pass safely the peak runoff of a 10-year, 6-hour precipitation event for temporary diversions, a 100-year, 24-hour precipitation event for permanent diversions or larger events as specified by the Department. However, the capacity of the channel itself shall be at least equal to the capacity of the unmodified stream channel immediately upstream and downstream of the diversion.

(7)   When no longer needed to achieve the purpose for which they were authorized, all temporary stream channel diversions shall be removed and the affected land regraded and revegetated in accordance with Sections 460:20-43-9, 460:20-43-10, 460:20-43-11, 460:20-43-43, and 460:20-43-40. At the time diversions are removed downstream water treatment facilities previously protected by the diversion shall be modified or removed to prevent overtopping or failure of the facilities. This requirement shall not relieve the operator who conducts the underground mining activities from maintenance of a water treatment facility required under this Subchapter of the permit.

(8)   When permanent diversions are constructed or stream channels restored, after temporary diversions, the operator shall:

(A)   Restore, enhance where practicable, or maintain natural riparian vegetation on the banks of the stream;

(B)   Establish or restore the stream to its natural meandering shape of an environmentally acceptable gradient, as determined by the Department;

(C)   Establish or restore the stream to a longitudinal profile and cross-section, including aquatic habitats (usually a patter of riffles, pools, and drops rather than a uniform depth) that approximate premining stream channel characteristics.

(c)   Diversion of miscellaneous flows.

(1)   Miscellaneous flows, which consist of all flows except for perennial and intermittent streams, may be diverted away from disturbed areas if required or approved by the Department. Miscellaneous flows shall include ground-water discharges and ephemeral streams.

(2)   The design, location, construction, maintenance, and removal of diversions of miscellaneous flows shall meet all of the performance standards set forth in Subsection (a) of this Section.

(3)   The requirements of Paragraph (a) (2) (B) of this Section shall be met when the temporary and permanent diversions for miscellaneous flows are designed so that the combination of channel, bank and flood-plain configuration is adequate to pass safely the peak runoff of a 2-year, 6-hour precipitation event for a temporary diversion and a 10-year, 6-hour precipitation event for a permanent diversion.

[Source: Amended at 12 Ok Reg 3592, eff 10-12-95]