Current through Register Vol. XLI, No. 37, September 13, 2024
Section 38-4-3 - Classification of Dams3.1. Types of Dams. 3.1.a. Embankment dams are usually constructed of material which exhibits rock-like or soil-like properties.3.1.b. Coal waste disposal dams are usually constructed of coal refuse and are utilized for impoundment of coal slurry from coal preparation plants.3.1.c. Road Fills: If the secretary finds that a road fill has become a hazard to human life or property through the frequent or continuous impoundment of water, he or she may order the owner of that road fill to take all steps that are necessary to protect life or property in accordance with the emergency powers provided under W. Va. Code § 22-14-10. 3.1.c.1. A certificate of approval will not be required for road fills.3.1.d. Bridges: If the secretary finds that a bridge has become a hazard to human life or property through the frequent or continuous impoundment of water, he or she may order the owner of that bridge to take all steps that are necessary to protect life or property in accordance with the emergency powers provided under W. Va. Code § 22-14.10. 3.1.d.1. A certificate of approval will not be required for bridges.3.1.e. Stream Encroachments: If the owner proposes to restrict a natural drain way by filling or by other artificial means such that restriction can or will impound water, and the fill and resulting reservoir will meet the height and storage requirements of a 'dam' as defined in these rules, the owner is responsible for obtaining a certificate of approval prior to its placement.3.2. Dam Related Measurements 3.2.a. Dam Height: The height of a dam is measured from the crest or uppermost point on the dam to the lowest point in the natural bed of the stream or watercourse at the downstream toe of the dam.3.2.b. Measuring Reservoir Volume: For purposes of determining whether a dam meets the criteria set forth in section 2.7 of these rules as applied to reservoir volume calculations, the volume must be calculated at the crest elevation of the dam.3.2.c. Incised Reservoirs: The height of embankment of an incised reservoir must be measured from the crest of or uppermost point on the dam to the lowest point in the natural bed of the stream or watercourse at the downstream toe or the dam. Reservoir volume must be calculated from the crest of the embankment to the elevation of the lowest point in the natural bed of the stream or watercourse at the downstream toe.3.3. Dams in Series: If the Secretary determines that a series or combination of water-impounding structures within the same watercourse or within the tributaries of such watercourse, which cumulatively meet the definition of "dam" set forth in section 2.7 of these rules constitute a hazard to human life, and failure of one or more of the impounding structures may induce failure of any or all of the remaining impounding structures, the Secretary may require the owner or owners of each impounding structure to comply with the requirements of these rules.3.4. Hazard Classification of Dams: The applicant for a certificate of approval must propose the hazard classification based upon classification guidelines listed in Section 3.4.b of these rules and the hazard evaluation performed pursuant to this Section of these rules. The classification proposed by an applicant is subject to approval by the Secretary.3.4.a. Changes in Dam Classification: The Secretary will periodically review the hazard classification of each dam subject to these rules and may reclassify a dam if the determines that the hazard potential has changed. The owner shall be notified by the Department of any hazard classification change.3.4.b. Hazard Classifications 3.4.b.1. Class A Dams: Class A dams are those dams located in rural or agricultural areas where failure may damage non-residential and normally unoccupied buildings, rural or agricultural land, or secondary highways. Failure of Class A dam would cause only a loss of the dam itself and a loss of property use, such as use of related roads, with little additional damage to adjacent property. Any impoundment exceeding twenty-five (25) feet in height measured at the downstream toe or two hundred (200) acre-feet storage volume or having a watershed exceeding five hundred (500) acres should not be class A dam.3.4.b.2. Class B Dams: Class B dams are those dams located in predominantly rural or agricultural areas where failure may damage isolated homes, primary highways, or minor railroads or may cause the interruption of public utility services. Failure of a Class B dam may cause great damage to property and project operations. Loss of human life resulting from failure of a class B dam must be unlikely.3.4.b.3. Class C Dams: Class C dams are those dams located where failure may cause a loss of human life or serious damage to homes, industrial and commercial buildings, important public utilities, primary highways or main haul roads. This classification must be used if failure would cause possible loss of human life.3.4.c. Assessment of Hazards and Consequences of Failure. All new Applications and expansions to existing impoundments must submit a complete Assessment of Hazards and Consequences of Failure (AHCF) in narrative form, certified by a Registered Professional Engineer (RPE), that addresses potential risk and impacts resulting from failure that could occur from the construction and/or operation of the facility and addresses the following:3.4.c.1. Downstream Hazard: In evaluating the hazard potential of a dam in order to determine its hazard classification, a complete evaluation of the downstream area which will be affected in the event of dam failure must be performed. A sudden flooding of inhabited land, a water flow with damaging velocity, a wall of water, or the flooding of inhabited structures will all be deemed to have the potential to result in a loss of human life. The planned or potential future development of downstream areas must also be considered when evaluating hazard classification.3.4.c.2. Dam Break Analysis: A downstream breach analysis must be performed to evaluate and map the downstream inundation area under assumed normal conditions and overtopping failure conditions. The Secretary may waive the downstream breach analysis for class A or class B dam where downstream conditions prevent any future introduction of new facilities or residences that thereby change the hazard classification of the dam.3.4.c.3. Risk Assessment: The Secretary may consider a risk assessment for justifying a reduced structure hazard classification based upon failure of the dam by overtopping. The applicant for a certificate of approval must demonstrate through appropriate calculations that all affected dwellings will be inundated and evacuated prior to the dam failure and that property damage and potential loss of human life resulting from the dam failure will not be significantly increased from that which occurred immediately prior to the dam failure.3.4.c.4. Emergency Planning: For a class C high hazard structure or if a dangerous condition exists, notification and action procedures shall be formulated by the operator or owner, for public protection and remedial action in the event of an emergency. All emergency procedures must be submitted and approved.