690-020-0022 Definitions Unless the context requires otherwise, the following definitions apply in OAR Chapter 690, Division 20: (1) “Abutment” means a natural valley or canyon side against which the Dam is built; (2) “Acre-feet” means the unit of volume equal to one acre covered with one foot of Water (325,851 gallons); (3) “Annual Exceedance Probability Flood” means the likelihood of a specific flood flow being equaled to or exceeded in any given year at that specific location, expressed as a percentage; (4) “As-built Drawing” means an engineering drawing of a Dam as it was actually constructed, noting all differences between original design and actual constructed condition; (5) “Conduit” means a closed conveyance used to release Water through a Dam; (6) “Core” means a soil of low permeability within an Embankment Dam; (7) “Construct” has the meaning given to the term in ORS 540.443; (8) "Constructing" has the same meaning as "Construct"; (9) "Crest" means the top of the Dam; (10) “Cutoff Trench” means a trench excavated beneath the Dam Foundation and backfilled with low permeability material to retard Water seepage; (11) “Dam” has the meaning given to the term in ORS 540.443; (12) “Dam Failure” has the meaning given to the term in ORS 540.443; (13) “Department” means the Oregon Water Resources Department; (14) “Director” means the Director of the Oregon Water Resources Department; (15) “Embankment” means an engineered earth fill; (16) “Emergency Action Plan” or “EAP” has the meaning given to the term in ORS 540.443; (17) “Engineer” means an individual who is registered in this state and holds a valid certificate to practice engineering in this state as provided under ORS 672.002 to 672.325; (18) “Engineer of Record” means a professional engineer registered in Oregon retained by a Dam owner to analyze, plan, and design a Dam to current safety standards, to oversee safe construction of a Dam, to supervise Modification or Removal of a Dam, or to oversee corrective actions identified by the Department, or to otherwise administer activities for a Dam; (19) “Foundation” means the ground surface upon which a Dam is constructed; (20) “Freeboard” means the vertical distance between the high-water level in the reservoir and the low spot on the Crest; (21) “Gate” or “Valve” means a permanent device for regulating Water flow through the Dam; (22) “Hazard Rating” means the categorization of a Dam established by the Department based on the potential damage to life, property, or public infrastructure downstream of a Dam in the event of a Dam Failure; (23) "Height" means the maximum height of the Dam above natural ground as measured at the maximum section along the Dam's longitudinal axis; (24) “High Hazard Rating” or “High Hazard” has the meaning given to the term in ORS 540.443; (25) “Inflow Design Flood” or “IDF” means the peak flood flow that the Engineer of Record will design to safely pass over or through the Spillway; (26) “Low Hazard Rating” or “Low Hazard” means that if a Dam were to fail, loss of life would be unlikely, and damage to property or public infrastructure would not be extensive; (27) “Maintenance Action” has the meaning given to the term in ORS 540.443; (28) “Modification” means changes to a Dam that have a potential impact on the safe functioning of the dam, are to an extent that the modified dam structures no longer conform to the original design, and do not include modifying Dam Height, performing Maintenance Actions, or Removal of a Dam; (29) “Person” has the meaning given to the term in ORS 536.007; (30) “Potentially Unsafe” has the meaning given to the term in ORS 540.443; (31) “Pressurized Conduit” means any pipe that penetrates into a Dam so that there is hydrostatic pressure due to the location of a Gate, Valve, or pipe connection; (32) “Probable Maximum Flood” or “PMF” means the largest flood that could occur at a specific location, determined by the most severe set of atmospheric, soil moisture, and snowpack conditions that are reasonably possible at that location; (33) "Removal" means demolishing all, or a portion of, the Dam structure permanently preventing storage of Water and allowing safe and natural passage of flood flows downstream; (34) “Significant Hazard Rating” or “Significant Hazard” has the meaning given to the term in ORS 540.443; (35) “Soil Filter” means soil with a gradation designed to inhibit movement of adjacent, finer grained soils; (36) “Spillway” means any structure constructed to bypass Water, including flood waters, to prevent Water overtopping the Crest; (37) “State Engineer” means an Engineer employed by the Department that is either the director or a principal assistant working for the director as described in ORS 536.032; (38) “Tank” means a fully-enclosed (bottom and sides) hydraulic structure made from metal, reinforced concrete, rigid fiberglass, or plastic that provides its own Water-sealing and structural stability; (39) “Toe Drain” is a drainage structure designed to collect and remove seepage Water from the toe of the Dam and to discharge this Water in a manner where it can be measured; (40) “Unsafe” has the meaning given to the term in ORS 540.443; (41) “Water” means water or wastewater; (42) “Zoned Embankment” means an Embankment Dam with a Core of low permeability materials, Soil Filter materials, drainage, and other materials placed to improve performance and safety of the Dam. Statutory/Other Authority: ORS 536.027, 540.488 Statutes/Other Implemented: ORS 540.443 History: WRD 3-2020, amend filed 06/29/2020, effective 07/01/2020 WRD 2-2015, f. & cert. ef. 3-17-15 WRD 7-2009, f. 12-7-09, cert. ef. 1-1-10 WRD 12-1986, f. & ef. 10-3-86