Arizona Administrative Code › Title 12 - NATURAL RESOURCES › Chapter 15 - Department of Water Resources › Article 12 - DAM SAFETY PROCEDURES › Section R12-15-1202 - Definitions

Current through Register Vol. 30, No. 28, July 12, 2024
In addition to the definitions provided in A.R.S. §
									45-1201,
				  the following definitions are applicable to this Article:
1. "Alteration or repair of an existing dam or appurtenant
				  structure" means to make different from the originally approved construction
				  drawings and specifications or current condition without changing the height or
				  storage capacity of the dam or reservoir, except for ordinary repairs and
				  general maintenance as prescribed in
				  R12-15-1217.
2. "Appurtenant structure" means any structure that is
				  contiguous and essential to the safe operation of the dam including
				  embankments, saddle dikes, outlet works and controls, diversion ditches,
				  spillway and controls, access structures, bridges, and related housing at a
				  dam.
3. "Classification of dams" means the placement of dams into
				  categories based upon an evaluation of the size and hazard potential,
				  regardless of the condition of the dam.
4. "Concrete dam" means any dam constructed of concrete,
				  including arch, gravity, arch-gravity, slab and buttress, and multiple arch
				  dams. A dam that only has a concrete facing is not a concrete dam.
5. "Construction" means any activity performed by the owner
				  or someone employed by the owner that is related to the construction,
				  reconstruction, repair, enlargement, removal, or alteration of any dam, unless
				  the context indicates otherwise. Construction is performed after approval of an
				  application and before issuance of a license.
6. "Dam failure inundation map" means a map depicting the
				  maximum area downstream from a dam that would be flooded in the event of the
				  worst condition failure of the dam.
7. "Department" means the Arizona Department of Water
				  Resources.
8. "Director" means the Director of the Arizona Department of
				  Water Resources or the Director's designee.
9. "Embankment dam" means a dam that is constructed of earth
				  or rock material.
10. "Emergency spillway" means a spillway designed to safely
				  pass the inflow design flood routed through the reservoir. If the flow is
				  controlled by gates, it is a controlled spillway. If the flow is not controlled
				  by gates, it is an uncontrolled spillway.
11. "Engineer" means a Professional Engineer registered and
				  licensed in accordance with A.R.S. Title 32, Chapter 1, with proficiency in
				  engineering and knowledge of dam technology.
12. "Enlargement to an existing dam or appurtenant structure"
				  means any alteration, modification, or repair that increases the vertical
				  height of a dam or the storage capacity of the reservoir.
13. "Flashboards" mean timber, concrete, or steel sections
				  placed on the crest of a spillway to raise the retention water level that may
				  be quickly removed at time of flood either by a tripping device or by designed
				  failure of the flashboards or their supports.
14. "Flood control dam" means a dam that uses all of its
				  reservoir storage capacity for temporary impoundment of flood waters and
				  collection of sediment or debris.
15. "Hazard potential" means the probable incremental adverse
				  consequences that result from the release of water or stored contents due to
				  failure or improper operation of a dam or appurtenances.
16. "Hazard potential classification" means a system that
				  categorizes dams according to the degree of probable incremental adverse
				  consequences of failure or improper operation of a dam or appurtenances. The
				  hazard potential classification does not reflect the current condition of the
				  dam with regard to safety, structural integrity, or flood routing
				  capacity.
17. "Height" means the vertical distance from the lowest
				  elevation of the outside limit of the barrier at its intersection with the
				  natural ground surface to the spillway crest elevation. For the purpose of
				  determining jurisdictional status, the lowest elevation of the outside limit of
				  the barrier may be the outlet pipe invert elevation if the outlet is
				  constructed below natural ground.
18. "Impound" means to cause water or a liquid to be confined
				  within a reservoir and held with no discharge.
19. "Incremental adverse consequences" means under the same
				  loading conditions, the additional adverse consequences such as economic,
				  intangible, lifeline, or human losses, that would occur due to the failure or
				  improper operation of the dam over those that would have occurred without
				  failure or improper operation of the dam.
20. "Inflow design flood" or "IDF" means the reservoir flood
				  inflow magnitude selected on the basis of size and hazard potential
				  classification for emergency spillway design requirements of a dam.
21. "Intangible losses" means incremental adverse
				  consequences to property that are not economic in nature, including property
				  related to social, cultural, unique, or resource-based values, including the
				  loss of irreplaceable and unique historic and cultural features; long-lasting
				  pollution of land or water; or long-lasting or permanent changes to the
				  ecology, including fish and endangered species habitat identified and evaluated
				  by a public natural resource management or protection agency.
22. "Jurisdictional dam" means a barrier that meets the
				  definition of a dam prescribed in A.R.S. §
									45-1201
				  that is not exempted by
				  R12-15-1203
				  over which the Department of Water Resources exercises jurisdiction.
23. "Levee" means an embankment of earth, concrete, or other
				  material used to prevent a watercourse from spreading laterally or overflowing
				  its banks. A levee is not used to impound water.
24. "License" means license of final approval issued by the
				  Director upon completion or enlargement of a dam under A.R.S. §
									45-1209.
25. "Lifeline losses" mean disruption of essential services
				  such as water, power, gas, telephone, or emergency medical services.
26. "Liquid-borne material" means mine tailings or other
				  milled ore products transported in a slurry to a storage impoundment.
27. "Maximum credible earthquake" means the most severe
				  earthquake that is believed to be possible at a point on the basis of geologic
				  and seismological evidence.
28. "Maximum water surface" means the maximum elevation of
				  the reservoir water level attained during routing of the inflow design
				  flood.
29. "Natural ground surface" means the undisturbed ground
				  surface before excavation or filling, or the undisturbed bed of the stream or
				  river.
30. "Outlet works" means a closed conduit under or through a
				  dam or through an abutment for the controlled discharge of the contents
				  normally impounded by a dam and reservoir. The outlet works include the inlet
				  and outlet structures appurtenant to the conduit. Outlet works may be
				  controlled or uncontrolled.
31. "Probable" means likely to occur, reasonably expected,
				  and realistic.
32. "Probable maximum flood" or "PMF" means the flood runoff
				  expected from the most severe combination of critical meteorologic and
				  hydrologic conditions that are reasonably possible in the region, including
				  rain and snow where applicable. 1/2 PMF is that flood represented by the flood
				  hydrograph with ordinates equal to 1/2 the corresponding ordinates of the PMF
				  hydrograph.
33. "Probable maximum precipitation" means the greatest depth
				  of precipitation for a given duration that is theoretically physically possible
				  over a particular size storm area at a particular geographical location at a
				  particular time of year.
34. "Reservoir" means any basin that contains or is capable
				  of containing water or other liquids impounded by a dam.
35. "Residual freeboard" means the vertical distance between
				  the highest water surface elevation during the inflow design flood and the
				  lowest point at the top of the dam.
36. "Restricted storage" means a condition placed on a
				  license by the Director to reduce the storage level of a reservoir because of a
				  safety deficiency.
37. "Saddle dike or saddle dam" means any dam constructed in
				  a topographically low area on the perimeter of a reservoir, required to contain
				  the reservoir at the highest water surface elevation.
38. "Safe" means that a dam has sufficient structural
				  integrity and flood routing capacity to make failure of the dam
				  unlikely.
39. "Safe storage level" means the maximum reservoir water
				  surface elevation at which the Director determines it is safe to impound water
				  or other liquids in the reservoir.
40. "Safety deficiency" means a condition at a dam that
				  impairs or adversely affects the safe operation of the dam.
41. "Safety inspection" means an investigation by an engineer
				  or a person under the direction of an engineer to assess the safety of a dam
				  and determine the safe storage level for a reservoir, which includes review of
				  design reports, construction documents, and previous safety inspection reports
				  of the dam, spillways, outlet facilities, seepage control and measurement
				  systems, and permanent monument or monitoring installations.
42. "Spillway crest" means the highest elevation of the floor
				  of the spillway along a centerline profile through the spillway.
43. "Storage capacity" means the maximum volume of water,
				  sediment, or debris that can be impounded in the reservoir with no discharge of
				  water, including the situation where an uncontrolled outlet becomes plugged.
				  The storage capacity is reached when the water level is at the crest of the
				  emergency spillway, or at the top of permanently mounted emergency spillway
				  gates in the closed position. Storage capacity excludes dead storage below the
				  natural ground surface.
44. "Surcharge storage" means the additional water storage
				  volume between the emergency spillway crest or closed gates, and the top of the
				  dam.
45. "Total freeboard" means the vertical distance between the
				  emergency spillway crest and the top of the dam.
46. "Unsafe" means that safety deficiencies in a dam or
				  spillway could result in failure of the dam with subsequent loss of human life
				  or significant property damage.