Subchapter D. STRUCTURAL REQUIREMENTS FOR IMPOUNDMENTS

§ 89.101. General requirements.

 (a)  Impoundments shall meet the structural design, construction and other requirements of this subchapter. The detailed design plan for large impoundments as described in §  89.111(a) (relating to large impoundments) or when impoundments meet or exceed the MSHA size classification or other criteria of 30 CFR 77.216(a) (relating to water sediment or slurry impoundment and impounding structures; general) shall be prepared by or under the direction of, and certified by, a qualified registered professional engineer with assistance, as necessary, from experts in related fields such as geology, land surveying and landscape architecture. The detailed design plan for other impoundments shall be prepared by or under the direction of, and certified by, a qualified registered professional engineer or qualified registered professional land surveyor.

 (b)  An impoundment as described in §  89.111(a) or when impoundments meet or exceed the MSHA size classification or other criteria of 30 CFR 77.216(a) shall be inspected during construction and certified after construction and annually thereafter by a qualified registered professional engineer until removal of the structure or release of the performance bond. Impoundments other than those described in §  89.111(a) or impoundments which do not meet or exceed the MSHA size classification or other criteria of 30 CFR 77.216(a) shall be inspected during construction and certified after construction and annually thereafter, by a qualified registered professional engineer or qualified registered professional land surveyor until removal of the structure or release of the performance bond. The professional engineer or professional land surveyor making the inspections or certifications shall be experienced in the construction of impoundments. A certification report shall include monitoring and instrumentation results and a statement regarding the condition of the impoundment. The impoundment shall be certified that it has been constructed and is being maintained as designed and in accordance with the approved plan and applicable performance standards.

 (c)  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 less than 20 feet in height or 20 acre feet of storage 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 will then notify the appropriate agencies that other emergency procedures are required to protect the public. The permittee shall make and retain a record of the inspection, including record of actions taken to correct deficiencies found in the inspection. A copy of the record shall be provided to the Department on request.

 (d)  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 requirement of §  89.111(b).

   The provisions of this §  89.101 amended under the Surface Mining Conservation and Reclamation Act (52 P. S. § §  1396.1—1396.19a); the Bituminous Mine Subsidence and Land Conservation Act (52 P. S. § §  1406.1—1406.21); 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).

 Each application shall include a plan for each proposed impoundment within the permit area. Each plan shall:

   (1)  Contain a description, map and cross section of the structure and its location.

   (2)  Contain preliminary hydrologic and geologic information required to assess the hydrologic impact of the structure.

   (3)  Contain a survey describing the potential effect on the structure from subsidence of the subsurface strata resulting from past underground mining operations.

   (4)  Include a geotechnical investigation, design and construction requirements for the structure, including a stability analysis if the structure is more than 20-feet high or impounds more than 20 acre-feet.

   (5)  Describe the operation and maintenance requirements for each structure.

   The provisions of this §  89.110 adopted December 19, 1980, 10 Pa.B. 4789, effective July 31, 1982, 12 Pa.B. 2382; reserved July 30, 1982, 12 Pa.B. 2473, effective July 31, 1982, 12 Pa.B. 2382.

PERFORMANCE STANDARDS

§ 89.111. Large impoundments.

 (a)  Large impoundments are those where:

   (1)  The structures are located on a water course, and 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)  The structures are not located on a watercourse and have no contributory drainage, but 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)  Large impoundments shall be designed, constructed and maintained in accordance with the Dam Safety and Encroachment Act (32 P. S. § §  693.1—693.27) and Chapter 105 (relating to dam safety and waterway management).

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

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

   (2)  Have an appropriate combination of principal and emergency spillway to discharge safely the runoff from a 100-year, 24-hour precipitation event, or larger if required by the Department.

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

   The provisions of this §  89.111 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 June 25, 1993, effective June 26, 1993, 23 Pa.B. 3075. Immediately preceding text appears at serial pages (159037) to (159038).

 An impoundment shall be designed in accordance with the United States Soil Conservation Service’s Pennsylvania Field Office Technical Guide, Section IV, Standards 350, ‘‘Sediment Basin,’’ and 373, ‘‘Pond,’’ or United States Soil Conservation Service 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. Each impoundment shall be certified that it has been constructed and is being maintained as designed and in accordance with the approved plan and all applicable performance standards. These structures shall also meet the following requirements:

   (1)  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 is being impounded may be riprapped or otherwise stabilized. Areas in which the vegetation is not successful or where rills and gullies develop shall be repaired and revegetated in accordance with §  89.86 (relating to revegetation).

   (2)  Ponds shall be examined annually by the operator for structural weakness, erosion and other hazardous conditions. If structural weakness, erosion or other hazardous conditions exist, the operator shall immediately notify the Department.

   (3)  Plans for enlargement, reduction in size, reconstruction or other modification of dams or impoundments shall be submitted to the Department and shall comply with the requirements of §  86.52 (relating to permit revisions). 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.

   (4)  Emergency spillways may not discharge unless precipitation exceeds a 10-year, 24-hour rainfall event. Precipitation includes:

     (i)   Snow melt, or a combination snow melt and rainfall event.

     (ii)   Multiple rainfall events occurring within the design drawdown period of the pond.

   The provisions of this §  89.112 amended under the Surface Mining Conservation and Reclamation Act (52 P. S. § §  1396.1—1396.19a); the Bituminous Mine Subsidence and Land Conservation Act (52 P. S. § §  1406.1—1406.21); 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).

   The provisions of this §  89.112 adopted July 30, 1982, 12 Pa.B. 2473, effective July 31, 1982, 12 Pa.B. 2382; amended June 15, 1990, 20 Pa.B. 3383, effective July 27, 1991, 21 Pa.B. 3316; amended December 15, 1995, effective December 16, 1995, 25 Pa.B. 5821. Immediately preceding text appears at serial pages (199256) to (199257).

   This section cited in 25 Pa. Code §  89.89 (relating to permanent impoundments).