N.M. Admin. Code § 19.8.20.2014

Current through Register Vol. 36, No. 1, January 14, 2025

Section 19.8.20.2014 - HYDROLOGIC BALANCE: SEDIMENTATION PONDS

A. When required under 19.8.20.2010 NMAC sedimentation ponds shall be used individually or in series and shall:

(1) be constructed and certified before any disturbance of the undisturbed area to be drained into the pond and, in addition, for underground mines prior to any discharge of water to surface waters from underground mine workings.

(2) be located as near as possible to the disturbed area and out of perennial streams, unless approved by the director.

(3) meet all the criteria of 19.8.20 NMAC.

(4) be certified to the director by a qualified registered professional engineer as having been constructed as designed and approved in the permit. Sediment ponds that do not meet the size or other criteria of 30 CFR 77.216(a) shall be certified by either a qualified registered professional engineer or qualified registered professional land surveyor.

(5) be designed, constructed, maintained and inspected in accordance with 19.8.20.2017 NMAC.

(6) be maintained until removal is authorized by the director and the disturbed area has been stabilized and revegetated.

B. Sedimentation ponds shall be designed, constructed and maintained to provide adequate sediment storage volume and provide for periodic sediment removal sufficient to maintain adequate volume for the design event.

C. Sedimentation ponds shall provide the required theoretical detention time for the water inflow or runoff entering the pond from a 10-year, 24-hour precipitation event (design event) plus the average inflow from any underground mine. The operator will comply with the applicable state laws and the regulations of the state engineer pertaining to the detention of water.

D. The water storage resulting from inflow shall be removed by a non-clogging dewatering device, conduit spillway, or other methods approved by the director. Stationary dewatering devices shall not be located at a lower elevation than the maximum elevation of the sedimentation storage volume.

E. Each person who conducts surface coal mining operations shall design, construct, and maintain sedimentation ponds to prevent short circuiting to the extent possible.

F. The design, construction, and maintenance of a sedimentation pond or other sediment control measures in accordance with 19.8.20 NMAC shall not relieve the person from compliance with applicable effluent limitations as contained in 19.8.20.2010 NMAC.

G. A sedimentation pond shall include either a combination of principal and emergency spillways or a single spillway configured as specified in Paragraph (1) of Subsection G of 19.8.20.2014 NMAC, designed and constructed to safely pass the applicable design precipitation event specified in Paragraph (2) of Subsection G of 19.8.20.2014 NMAC, except as set forth in Paragraph (3) of Subsection G of 19.8.20.2014 NMAC.

(1) The director may approve a single open-channel spillway that is:

(a) of nonerodible construction and designed to carry sustained flows; or

(b) earth or grass-lined and designed to carry short-term infrequent flows at nonerosive velocities where sustained flows are not expected.

(2) Except as specified in Paragraph (3) of Subsection G of 19.8.20.2014 NMAC, the required design precipitation event for spillways for sedimentation ponds is:

(a) for a sedimentation pond meeting the size or other criteria of mine safety and health administration 30 CFR 77.216(a), a 100-year 6 hour event, or greater event as specified by the director;

(b) for a sedimentation pond not meeting the size or other criteria of 30 CFR 77.216(a), a 25-year 6-hour event, or greater event as specified by the director.

(3) In lieu of meeting the requirements in Paragraph (1) of Subsection G of 19.8.20.2014 NMAC, the director may approve a sedimentation pond that relies primarily on storage to control the runoff from the design precipitation event when it is demonstrated by the operator and certified by a qualified registered professional engineer or qualified registered professional land surveyor that the sedimentation pond will safely control the design precipitation event, the water from which shall be safely removed in accordance with current, prudent, engineering practices. Such a sedimentation pond shall be located where failure would not be expected to cause loss of life or serious property damage. The following design criteria shall apply:

(a) in the case of a sedimentation pond meeting the size or other criteria of 30 CFR 77.216(a), it is designed to control the runoff from the probable maximum precipitation of a 6-hour event, or greater event as specified by the director;

(b) in the case of a sedimentation pond not meeting the size or other criteria of 30 CFR 77.216(a), it is designed to control the runoff of a 100-year, 6-hour event, or greater event as specified by the director.

H. The embankment foundation area shall be cleared of all organic matter, all surfaces sloped to no steeper than 1v:1h and the entire foundation surface scarified.

I. The fill material shall be free of sod, large roots, other large vegetative matter, and frozen soil, and in no case shall coal-processing waste be used.

J. The embankment area shall be compacted properly to ensure against excessive settlement.

K. When a sediment pond is removed, the land on which the pond is located and the affected area shall be regraded and revegetated in accordance with the approved permit.

N.M. Admin. Code § 19.8.20.2014

11-29-97; 19.8.20.2014 NMAC - Rn, 19 NMAC 8.2.20.2014, 9-29-2000