Delaware Administrative Code
Title 7 - Natural Resources and Environmental Control
5000 - Division of Watershed Stewardship
5103 - Delaware Dam Safety Regulations
Section 5103-2.0 - Definition of Terms
Current through Register Vol. 28, No. 3, September 1, 2024
The following words, terms, and phrases, when used in these Regulations, shall have the meanings ascribed to them except where the context clearly indicates a different meaning:
"Abandonment" means to render a dam non-impounding by dewatering and filling the reservoir created by that dam with solid materials and by diverting the natural drainageway around the site.
"Adverse consequences" means negative impacts that may occur upstream, downstream, or at other locations remote from the dam. The primary concerns are loss of human life, economic loss (including property damage), disruption of lifeline facilities, and environmental impact.
"Alterations", "modifications" or "repairs" means only alterations, modifications, or repairs to existing dam and appurtenant structures that may directly affect the operation, performance, or safety of the dam, spillway, outlet works, ancillary structures, or reservoir, as determined by the Department. This definition does not include maintenance or minor repairs.
"Application approval" means authorization in writing issued by the Department to an owner who has applied to the agency for permission to construct, reconstruct, enlarge, repair, alter, remove, maintain, operate, or abandon a dam and which specifies the conditions or limitations under which work is to be performed by the owner or under which approval is granted.
"Appurtenant works" include, but are not limited to, structures such as spillways, either in or separate from the dam; the reservoir and its rim; low-level outlet works; and water conduits such as tunnels, pipelines, or penstocks either through the dam or its abutments.
"As-Built Drawings" or" Record Drawings" mean the approved post-construction plans;
(1) With verification of all significant as-constructed values, dimensions, and elevations; and
(2) Bearing the seal of the supervising engineer responsible for certifying that to the best of his/her knowledge, the construction was completed in accordance with the approved plans and specifications or with changes approved by the Department.
"Auxiliary Spillway" means the second used spillway during flood flows which is not the emergency spillway.
"Breach" means partial removal of a dam, creating a channel through the dam to the original stream bottom elevation.
"Dam" shall mean any artificial barrier, including appurtenant works, with the ability to impound or divert water, wastewater, or liquid-borne materials. No obstruction in a canal used to raise or lower water shall be considered a dam. A fill or structure for highway or railroad use, or for any other purpose that may impound water, may be subject to review by the Department and shall be considered a dam if the criteria in these Regulations are found applicable and if it is classified as a high hazard potential or significant hazard potential dam.
"Danger reach" means that area downstream of a dam that will be flooded by the sudden release of waters resulting from failure of the dam.
"Days" when used in establishing deadlines, means calendar days including Sundays and holidays.
"Department" means the Delaware Department of Natural Resources and Environmental Control.
"Design freeboard" means the minimum freeboard which would exist during passage of the design flood.
"Dominant discharge" means the flow rate capacity, in cubic feet per second, of the stream channel considering steady, uniform flow.
"Emergency Action Plan" (EAP) means a plan prepared by the dam owner and approved by the Department that identifies emergency conditions at a dam and specifies preplanned actions to minimize loss of life and property damage in the event of a potential dam failure.
"Emergency condition" means a sudden unforeseen occurrence or condition requiring exigency or a circumstance that the Department determines constitutes a present or imminent danger to the public health or safety or to the environment. This includes, but is not necessarily limited to: breaches and all conditions leading to or causing a breach, overtopping, or any other condition in a dam and its appurtenant structures that may be construed as unsafe or threatening to life or property.
"Emergency Spillway" means the spillway capable of passing the spillway design storm with the principal and/or auxiliary spillway blocked.
"Enlargement" means any change in or addition to an existing dam or reservoir, which raises or may raise the water storage elevation of the water impounded by the dam.
"Floodplain" means that area along or adjacent to a stream or a body of water of that is capable of storing or conveying flood waters. As used herein, "floodplain" may or may not be the same area depicted as a special flood hazard zone on the Flood Insurance Rate Maps prepared by the Federal Emergency Management Agency.
"Formal inspection" means the inspection by a Delaware licensed professional engineer to reevaluate the safety and integrity of the dam and appurtenant structures to determine if the structure meets current design criteria, including a field inspection and a review of the records on project design, construction and performance.
"Freeboard" means the vertical distance to the top of a dam above the maximum design water surface elevation.
"Independent Review Board" means one or more independent professional engineers who are qualified in the design, construction and rehabilitation of dams to perform a review of the project design and construction.
"Informal Inspection" means the visual inspection of the dam by the dam owner or operator to detect apparent signs of deterioration or other deficiencies of the dam structure or function.
"Hazard potential" means the possible adverse incremental consequences that result from the release of water or stored contents due to failure of the dam or appurtenances. The hazard potential classification of a dam does not reflect in any way on the current condition of the dam and its appurtenant structures (e.g., safety, structural integrity, flood-routing capacity).
"Height of dam" means the vertical distance from the lowest point on the downstream toe of the dam to the lowest point on the top of the dam, independent of low points caused by partial failure or collapse.
"High Hazard Potential Dam" shall mean any dam whose failure or misoperation will cause probable loss of human life.
"Incremental" means the difference in impacts, under the same conditions (e.g., flood, earthquake, or other event), that would occur due to failure of the dam or those that would have occurred without failure of the dam and appurtenances.
"Inflow design flood" means the size of flood coming into the reservoir that is used as a basis for designing the dam.
"Low-hazard potential dam" means any dam whose failure or misoperation is unlikely to cause loss of human life but may cause minor economic and/or environmental losses.
"Maintenance" means routine activities associated with keeping the dam and ancillary structures in safe operating condition, including, but not limited to such activities as mowing and vegetation removal, cleaning drains, painting metal parts, lubricating and exercising mechanical parts, cleaning debris from channels and trash racks, etc.
"Maximum capacity" means the storage volume of a reservoir, in acre-feet, at the lowest point on the top of dam independent of low points caused by partial failure or collapse.
"Maximum storage elevation" means the elevation of the lowest point of the top of dam independent of low points caused by partial failure or collapse.
"Minor repairs" means activities that restore sections of the dam, spillway, outlet works, and ancillary structures which exhibit minor deterioration to their intended state and that do not require the alteration (permanent or temporary) of any facilities that would effect performance, operation or safety of the dam as determined by the Department.
"Normal depth" means the maximum vertical distance from the streambed invert at the upstream toe of the dam to the normal water surface.
"One-hundred year storm" means the storm which is estimated to have a one percent chance, or one chance in 100, of being equaled or exceeded in one year.
"Outlet" means an opening through which water can be freely discharged from a reservoir for a particular purpose.
"Overflow spillway" means any operating, emergency, or other spillway that discharges with a free water surface over or around the dam as opposed to an orifice, gate, or conduit that discharges through or beneath the dam or nearby ground.
"Owner" shall include any one or more of the following who owns, controls, operates, maintains, manages, or proposes to construct, reconstruct, enlarge, repair, alter, remove, or abandon a dam or reservoir: the state and its departments, institutions, agencies, and political subdivisions; every municipal or quasi-municipal corporation; every public utility; every district; every person; the duly authorized agents, lessees, or trustees of any of the foregoing; and receivers or trustees appointed by any court for any of the foregoing.
"Permit to Impound" means authorization in writing issued by the Department to an owner who has complied with the conditions specified in the Provisional Certificate to Impound issued by the Department, or has completed construction, reconstruction, enlargement, repair, or alteration of a dam, and which specifies the conditions or limitations under which the dam and reservoir are to be maintained and operated.
"Person" means any person, firm, association, organization, partnership, business trust, corporation, or company.
"Preliminary Hazard Classification" means the initial hazard potential classification determined by the Department based on approximate methods, and is not based on detailed analyses as described in paragraph 5.3 of these Regulations.
"Principal spillway" means the primary or first used spillway during normal inflow and flood flows.
"Probable" means likely to occur; reasonably expected; realistic.
"Probable Maximum Flood" (PMF) means the most severe flood considered possible in a specific region based on the Probable Maximum Precipitation (PMP), as determined by the National Weather Service.
"Probable Maximum Precipitation" (PMP) means the theoretically greatest depth of precipitation for a given duration that is physically possible, over a given size storm area, at a particular geographic location, at a certain time of year.
"Provisional Certificate to Impound" means temporary authorization in writing issued by the Department to the owner of a dam that existed prior to June 30, 2004, and that the Department has determined meets the criteria for regulation as contained in paragraph 3.1 of these Regulations, and which specifies the conditions that must be met by the dam owner to obtain a Permit to Impound.
"Reconstruction" means removal and replacement of an existing dam.
"Regular Inspection" means the visual inspection of a dam by a Delaware licensed professional engineer to detect any signs of deterioration in material, developing weaknesses or unsafe hydraulic or structural behavior.
"Removal" means complete elimination of the dam embankment or structure to restore the approximate original topographic contours of the valley.
"Reservoir" means any basin that contains or will contain impounded water, wastewater, or liquid-borne materials because it has been impounded by a dam.
"Secretary" means the Secretary of the Delaware Department of Natural Resources and Environmental Control.
"Significant Hazard Potential Dam" shall mean any dam whose failure or misoperation will cause possible loss of life, economic loss, environmental damage, disruption of lifeline facilities, or can impact other concerns.
"Standard project flood" means the most severe flood considered reasonably characteristic of the specific region. This is calculated for a specific dam site using one or more of the recognized methods acceptable to the Department.
"State or state" means the State of Delaware.
"Spillway" means a structure other than low flow outlets, over or through which flood flows are discharged.
"Spillway Design Storm" means the storm upon which the hydraulic capacity of the spillway structure is designed.
"Supervising Engineer" shall mean the design engineer who is responsible for conducting dam construction quality assurance inspections in order to certify the construction has been completed in accordance with the approved plans and specifications.
"Sunny day failure" means the failure of a dam with the water level at the normal pool elevation and no rainfall.
"Toe of dam" means the junction of the downstream face of a dam with the ground surface or the invert of the outlet pipe whichever is the lowest point.
