§ 817.34 - How must I protect the hydrologic balance?

§ 817.34 How must I protect the hydrologic balance?

(a) You, the permittee, must conduct all underground mining and reclamation activities in a manner that will -

(1) Minimize disturbance of the hydrologic balance within the permit and adjacent areas.

(2) Prevent material damage to the hydrologic balance outside the permit area. Material damage resulting from subsidence may not constitute material damage to the hydrologic balance outside the permit area if that damage is repaired or corrected under § 817.40 or § 817.121(c) of this part.

(3) Protect streams in accordance with §§ 784.28 and 817.57 of this chapter.

(4) Assure the replacement of water supplies to the extent required by § 817.40 of this part.

(5) Protect existing water rights under state law.

(6) Support approved postmining land uses in accordance with the terms and conditions of the approved permit and the performance standards of this part.

(7) Comply with the hydrologic reclamation plan as submitted under § 784.22 of this chapter and approved in the permit.

(8) Protect groundwater quality by using best management practices to handle earth materials and runoff in a manner that avoids the formation of acid or toxic mine drainage and by managing excavations and other disturbances to prevent or control groundwater degradation. The regulatory authority will determine the meaning of the term “best management practices” on a site-specific basis. At a minimum, the term includes equipment, devices, systems, methods, and techniques that the Director determines to be best management practices.

(9) Protect surface-water quality by using best management practices, as described in paragraph (a)(8) of this section, to handle earth materials, groundwater discharges, and runoff in a manner that -

(i) Prevents postmining discharges of acid or toxic mine drainage.

(ii) Prevents additional contribution of suspended solids to streamflow or runoff outside the permit area to the extent possible, using the best technology currently available.

(iii) Otherwise prevents water pollution.

(10) Protect surface-water quality and flow rates by handling earth materials and runoff in accordance with the steps outlined in the hydrologic reclamation plan and the surface-water runoff control plan approved in the permit in accordance with §§ 784.22 and 780.29 of this chapter, respectively.

(b)

(1) To the maximum extent practicable, you must use mining and reclamation practices that minimize water pollution, changes in flow, and adverse impacts on stream biota rather than relying upon water treatment to minimize those impacts.

(2) You must install, use, and maintain any necessary water-treatment facilities or water-quality controls if drainage control, materials handling, stabilization and revegetation of disturbed areas, diversion of runoff, mulching, and other reclamation and remedial practices are not adequate to meet the requirements of this section and § 817.42 of this part.

(c) The regulatory authority may require that you take preventive, remedial, or monitoring measures in addition to those set forth in this part to prevent material damage to the hydrologic balance outside the permit area.

(d)

(1) You must examine the runoff-control structures identified under § 784.29 of this chapter within 72 hours of cessation of each occurrence of the following precipitation events:

(i) In areas with an average annual precipitation of more than 26.0 inches, an event of a size equal to or greater than that of a storm with a 2-year recurrence interval. You must use the appropriate regional Natural Resources Conservation Service synthetic storm distribution to determine peak flow for a storm with that recurrence interval.

(ii) In areas with an average annual precipitation of 26.0 inches or less, a significant event of a size specified by the regulatory authority.

(2)

(i) You must prepare a report, which must be certified by a registered professional engineer, and submit the report to the regulatory authority within 30 days of cessation of the applicable precipitation event under paragraph (d)(1) of this section. The report must address the performance of the runoff-control structures, identify and describe any material damage to the hydrologic balance outside the permit area that occurred, and identify and describe the remedial measures taken in response to that damage.

(ii) The report prepared under paragraph (d)(2)(i) of this section may include all precipitation events that occur within 30 days of cessation of the applicable precipitation event under paragraph (d)(1) of this section.