Virginia Administrative Code › Title 4 - CONSERVATION AND NATURAL RESOURCES › Agency 25 - DEPARTMENT OF ENERGY › Chapter 31 - RECLAMATION REGULATIONS FOR MINERAL MINING › Part IV - Performance Standards › Section 4VAC25-31-500 - Water impoundments

Current through Register Vol. 40, No. 24, July 15, 2024
A.
				  Structures that impound water or sediment to a height of five feet or more
				  above the lowest natural ground area within the impoundment and have a storage
				  volume of 50 acre-feet or more, or impound water or sediment to a height of 20
				  feet or more regardless of storage volume, shall meet the following criteria
				  (noted in Chapter 13 (§ 45.2-1300 et seq.) of Title 45.2 of the Code of
				  Virginia):
1. Impoundments meeting or
				  exceeding the size criteria set forth in this section shall be designed
				  utilizing a spillway flood and hazard potential classification as specified in
				  the following table:
Class of Impoundment*
Spillway Design Flood (SDF)**
Minimum Threshold for Incremental
								Damage Analysis ***
High Hazard
PMF
0.50 PMF
Significant Hazard
0.50 PMF
100-year storm
Low Hazard
100-year storm
50-year storm
*Size and hazard potential classifications shall be
								proposed and justified by the operator and shall be subject to approval by the
								director. Present and projected development in the inundation zone downstream
								from the structure shall be used in determining the classification.
**The complete definitions of hazard potential are
								those contained in
								4VAC50-20-40.
***The establishment of rigid design flood criteria
								or standards is not intended. Safety must be evaluated in the light of
								peculiarities and local conditions for each impounding structure and in
								recognition of the many factors involved, some of which may not be precisely
								known. Such can only be done by competent, experienced engineering judgment,
								which the values in the table are intended to add to, not replace.
Reductions in the SDF may be evaluated by use of
					 incremental damage analysis described in
					 4VAC50-20-52.
					 Note that future development downstream may increase the required
					 SDF.
2. Impounding
				  structures shall be constructed, operated, and maintained such that they
				  perform in accordance with their design and purpose throughout their life.
a. Impoundments shall be designed and
				  constructed by or under the direction of a qualified professional engineer
				  licensed in Virginia and experienced in the design and construction of
				  impoundments.
b. The designs shall
				  meet the requirements of this section and use current prudent engineering
				  practices.
c. The plans and
				  specifications for an impoundment shall consist of a detailed engineering
				  design report that includes engineering drawings and specifications, with the
				  following as a minimum:
(1) The name of the
				  mine; the name of the owner; classification of the impounding structure as set
				  forth in this regulation; designated access to the impoundment and the location
				  with respect to highways, roads, streams and existing impounding structures and
				  impoundments that would affect or be affected by the proposed impounding
				  structure.
(2) Cross sections,
				  profiles, logs of test borings, laboratory and in situ test data, drawings of
				  principal and emergency spillways and other additional drawings in sufficient
				  detail to indicate clearly the extent and complexity of the work to be
				  performed.
(3) The technical
				  provisions as may be required to describe the methods of the construction and
				  construction quality control for the project.
(4) Special provisions as may be required to
				  describe technical provisions needed to ensure that the impounding structure is
				  constructed according to the approved plans and specifications.
d. Components of the impounding
				  structure, the impoundment, the outlet works, drain system and appurtenances
				  shall be durable in keeping with the design and planned life of the impounding
				  structure.
e. All new impounding
				  structures regardless of their hazard potential classification shall include a
				  device to permit draining of the impoundment within a reasonable period of
				  time, and at a minimum shall be able to lower the pool level six vertical
				  inches per day, as determined by the owner's professional engineer, subject to
				  approval by the director.
f.
				  Impoundments meeting the size requirements and hazard potential of high,
				  significant, or low shall have a minimum static safety factor of 1.5 for a
				  normal pool with steady seepage saturation conditions and a seismic safety
				  factor of 1.2.
g. Impoundments
				  shall be inspected and maintained to ensure that all structures function to
				  design specifications.
h.
				  Impoundments shall be constructed, maintained and inspected to ensure
				  protection of adjacent properties and preservation of public safety and shall
				  meet proper design and engineering standards under Chapter 13 (§ 45.2-1300
				  et seq.) of Title 45.2 of the Code of Virginia. Impoundments shall be inspected
				  at least daily by a qualified person, designated by the licensed operator, who
				  can provide prompt notice of any potentially hazardous or emergency situation
				  as required under § 45.2-1302 of the Code of Virginia. Records of the
				  inspections shall be kept and certified by the operator or his agent.
i. The operator will prepare an emergency
				  action plan (EAP) that includes the following information:
(1) A notification chart of persons or
				  organizations to be notified, the person or persons responsible for
				  notification, and the priority in which notifications are issued. Notifications
				  shall include at a minimum the division, the local government authority
				  responsible for emergency response, and the Virginia Department of Emergency
				  Management.
(2) A discussion of the
				  procedures used for timely and reliable detection, evacuation, and
				  classification of emergency situations considered to be relevant to the
				  structure and its setting.
(3)
				  Designation of responsibilities for EAP related tasks. Also, the EAP shall
				  designate the responsible party for making a decision that an emergency
				  situation no longer exists at the impounding structure. Finally, the EAP shall
				  include the responsible party and the procedures for notifying to the extent
				  possible any known local occupants, owners, or lessees of downstream properties
				  potentially impacted by a failure of the impounding structure.
(4) A section describing actions to be taken
				  in preparation for impoundment emergencies, both before and during the
				  development of emergency conditions.
(5) Dam break inundation maps. Each sheet of
				  such maps for high and significant potential hazard classification structures
				  shall be prepared and sealed by a professional engineer. Where possible,
				  inundation mapping in the EAP should be provided on sheets no larger than 11
				  inches by 17 inches to facilitate copying for emergency response.
(6) Appendices containing information that
				  supports and supplements the material used in the development of the EAP,
				  including plans for training, exercising, and updating the EAP.
(7) A section that identifies all parties
				  with assigned responsibilities in the EAP and signed certification by all of
				  those parties that a copy of the EAP has been received.
(8) Times periods for review or revision
				  acceptable to the director.
3. Impoundments shall be closed and abandoned
				  in a manner that ensures continued stability and compatibility with the
				  post-mining land use.
4. The
				  following are acceptable as design procedures and references:
a. The design procedures, manuals and
				  criteria used by the United States Army Corps of Engineers;
b. The design procedures, manuals and
				  criteria used by the United States Department of Agriculture, Natural Resources
				  Conservation Service;
c. The design
				  procedures, manuals and criteria used by the United States Department of
				  Interior, Bureau of Reclamation;
d.
				  The design procedures, manuals and criteria used by the United States
				  Department of Commerce, National Weather Service;
e. The design procedures, manuals and
				  criteria used by the United States Federal Energy Regulatory
				  Commission;
f. Federal Guidelines
				  for Dam Safety: Emergency Action Planning for Dam Owners, United States
				  Department of Homeland Security, Federal Emergency Management Agency, October
				  1998, Reprinted January 2004; FEMA 64 or as revised;
g. Federal Guidelines for Dam Safety:
				  Selecting and Accommodating Inflow Design Floods for Dams, United States
				  Department of Homeland Security, Federal Emergency Management Agency, October
				  1998, Reprinted April 2004; FEMA 94 or as revised; or
h. Other design procedures, manuals and
				  criteria that are accepted as current, sound engineering practices, as approved
				  by the director prior to the design of the impounding structure.