Section 90.112. Hydrologic balance: dams, ponds, embankments and impoundments—design, construction and maintenance

(a) Dams, ponds, embankments and impoundments that meet the following criteria shall be designed, constructed and maintained under Chapter 105 (relating to dam safety and waterway management):

(1) Dams located on a natural or artificial water course where one of the following applies:

(i) The contributory drainage area exceeds 100 acres.

(ii) The greatest depth of water at maximum storage elevation exceeds 15 feet.

(iii) The impounding capacity at maximum storage elevation exceeds 50 acre-feet.

(2) Structures used for the storage of water not located on a watercourse and which have no contributory drainage where the greatest depth of water, at maximum storage elevation, exceeds 15 feet and the impounding capacity, at maximum storage elevation, exceeds 50 acre-feet.

(b) The design, construction and maintenance of dams, ponds, embankments and impoundments shall achieve the minimum design criteria contained in the United States Soil Conservation Service’s Pennsylvania Field Office Technical Guide, Section IV, Standards 350 ‘‘Sediment Basin’’ and 378, ‘‘Pond,’’ or United States Soil Conservation Service’s Technical Release No. 60, Earth Dams and Reservoirs, whichever is applicable. The standards are incorporated by reference. In addition to the requirements in ‘‘Sediment Basin,’’ a minimum static safety factor of 1.3 is required. These structures shall meet the following requirements:

(1) The detailed design plan for a structure shall be prepared by and certified by a qualified registered professional engineer. Each impoundment shall be certified that the impoundment has been constructed and is being maintained as designed in accordance with the applicable performance standards.

(2) Each pond shall be inspected once every 3 months for structural weakness, erosion and other hazardous conditions. The person who conducts the coal refuse disposal activities shall make and retain records of the inspection, including records of actions taken to correct deficiencies found in the inspection. Copies of the records shall be provided to the Department on request.

(3) The entire embankment, including the surrounding areas disturbed by construction, shall be stabilized with respect to erosion by a vegetative cover or other means immediately after the embankment is completed. The active upstream face of the embankment where water will be impounded shall be riprapped or otherwise stabilized. Areas in which the vegetation is not successful or where rills and gullies develop shall be repaired and revegetated.

(4) Plans for enlargement, reduction in size, reconstruction or other modification of dams or impoundments shall be submitted to the Department and shall comply with this section. Except when a modification is required to eliminate an emergency condition, constituting a hazard to public health, safety or the environment, the plans shall be approved by the Department before modification begins.

(c) If the embankment is more than 20 feet in height as measured from the upstream toe of embankment to the crest of the emergency spillway, or has a storage volume of 20 acre feet or more, is located where failure could cause loss of life or serious property damage or otherwise poses a hazard to miners or the public, it must:

(1) Be stable under probable conditions of operation and be designed and constructed to achieve a static safety factor of 1.5 or a higher static safety factor required by the Department.

(2) Have an appropriate combination of principal and emergency spillways to safely pass, adequate storage capacity to safely contain, or a combination of storage capacity and spillway capacity to safely control, the probable maximum runoff from precipitation of a 6-hour precipitation event.

(3) Have a foundation investigation, as well as necessary laboratory testing of foundation material to determine the design requirements for foundation stability.

(d) An impoundment shall be inspected during construction and certified after construction, and annually thereafter, by a qualified registered professional engineer until removal of the structure. Certification reports shall include monitoring and instrumentation results and a statement regarding the condition of impoundment.

(e) An impoundment shall be examined by a qualified person designated by the operator at intervals not exceeding 7 days for structural weakness, erosion and other hazardous conditions. Impoundments with an embankment less than 20 feet in height as measured from the upstream toe of the embankment to the crest of the emergency spillway or which have a storage volume of less than 20 acre-feet shall be inspected once every 3 months unless otherwise required by the Department. If an examination or inspection discloses that a potential hazard exists, the person who examined the impoundment shall promptly inform the Department of the finding and provide a remedial action plan to protect the public. If adequate procedures cannot be formulated or implemented, the Department shall be notified immediately. The Department will then notify the appropriate agencies that other emergency procedures are required to protect the public. The permittee shall make and retain records of the inspection, including records of actions taken to correct deficiencies found in the inspection. Copies of the records shall be provided to the Department on request.

(f) Impoundments subject to 30 CFR 77.216-1 and 77.216-2 (relating to water, sediment or slurry impoundments and impounding structures; identification; and water, sediment or slurry impoundments and impounding structures; minimum plan requirements; changes or modifications; certification) shall have duplicate plans submitted to the District Manager of MSHA and to the Department. The Department may consider MSHA's review for impoundments. However, the Department will review impoundments under the requirements of subsection (a).

The provisions of this § 90.112 adopted December 19, 1980, 10 Pa.B. 4789, effective July 31, 1982, 12 Pa.B. 2382; amended July 30, 1982, 12 Pa.B. 2473, effective July 31, 1982, 12 Pa.B. 2382; amended February 17, 1984, 14 Pa.B. 524, effective August 4, 1984, 14 Pa.B. 2860; amended June 15, 1990, 20 Pa.B. 3383, effective July 27, 1991, 21 Pa.B. 3316; amended June 25, 1993, effective June 26, 1993, 23 Pa.B. 3075; amended December 15, 1995, effective December 16, 1995, 25 Pa.B. 5821; amended June 17, 2011, effective June 18, 2011, 41 Pa.B. 3084. Immediately preceding text appears at serial pages (207969) to (207971).

Notation

Authority

The provisions of this § 90.112 amended under the Surface Mining Conservation and Reclamation Act (52 P. S. § § 1396.1—1396.19a); The Clean Streams Law (35 P. S. § § 691.1—691.1001); and section 1920-A of The Administrative Code of 1929 (71 P. S. § 510-20).

Cross References

This section cited in 25 Pa. Code § 87.113 (relating to hydrologic balance: coal processing waste dams and embankments); 25 Pa. Code § 90.39 (relating to ponds, impoundments, banks, dams, embankments, piles and fills); 25 Pa. Code § 90.108 (relating to hydrologic balance: sedimentation ponds); 25 Pa. Code § 90.113 (relating to hydrologic balance: coal processing waste dams and embankments); and 25 Pa. Code § 90.130 (relating to coal refuse dams).