OHIO DAM SAFETY LAWS AND REGULATIONS 2007 Citation Ohio Dam Safety Laws are found in the Ohio Revised Code – (ORC) Title XV (enacted Oct. 10, 1963 and last amended March 2007. Administrative rules enacted by the Division of Water of the Department of Natural Resources supplement the permit and inspection laws and reflect Division of Water policy and procedures in carrying out the intent of the law (enacted April 15, 1972, revised Oct. 15, 1981, December 9, 1999, and May 15, 2006). History Construction of dams in Ohio dates back to the early 1800s when reservoirs were built to supply water to a state canal system used for agricultural trade and commerce. Legislation encouraging construction of dams in response to droughts was enacted in 1937, but the forerunner of Ohio’s current dam safety laws was enacted in 1963, when the Ohio Department of Natural Resources Division of Water became involved in dam safety. This law required construction permits for new dams. In 1969, following the failure of several dams in northeast Ohio, the General Assembly revised the law to include periodic inspections of existing structures. Definitions/Dam Classification Dams are defined as any artificial barrier together with any appurtenant works, which either does or may impound water or other liquefied material. Upground reservoirs and lagoons are considered to be dams. A fill or structure intended solely for highway or railroad use that does not permanently impound water or other liquefied material as determined by the chief is not considered a dam (Administrative Rules Chapter 3- 1501:21-3-01[E]). Dam height means the vertical dimension as measured from the elevation of the natural stream bed, watercourse, or lowest ground elevation at the downstream or outside toe of a dam to the elevation of the top of the dam (Administrative Rules Chapter 3-1501:21-3- 01[I]). Classification criteria for dams are found in the Administrative Rules Chapter 13- 1501:21-13-01. (1) A dam shall be placed in class I when sudden failure of the dam would result in probable loss of human life or structural collapse of at least one residence or one commercial or industrial business. Dams having a total storage volume greater than five thousand acre-feet or a height of greater than sixty feet shall be placed in class I. (2) Dams having a total storage volume greater than five hundred acre-feet or a height of greater than forty feet shall be placed in class II. A dam shall be placed in class II when failure of the dam would result in at least one of the following conditions, but loss of human life is not probable. (a) Disruption of a public water supply or wastewater treatment facility, release of health hazardous industrial or commercial waste, or other health hazards. (b) Flooding of residential, commercial, industrial, or publicly owned structures. (c) Flooding of high-value property. (d) Damage or disruption to major roads including but not limited to interstate and state highways, and the only access to residential or other critical areas such as hospitals, nursing homes, or correctional facilities as determined by the chief. (e) Damage or disruption to railroads, or public utilities. (f) Damage to downstream class I, II or III dams or levees, or other dams or levees of high value. Damage to dams or levees can include, but is not limited to, overtopping of the structure. (3) Dams having a height of greater than twenty-five feet or a total storage volume greater than fifty acre-feet shall be placed in class III. A dam shall be placed in class III when sudden failure of the dam would result in at least one of the following conditions, but loss of human life is not probable. (a) Property losses including but not limited to rural buildings not otherwise described in paragraph (A) of this rule, and class IV dams and levees not otherwise listed as high-value property in paragraph (A) of this rule. At the request of the dam owner, the chief may exempt dams from the criterion of this paragraph if the dam owner owns the potentially affected property. (b) Damage or disruption to local roads including but not limited to roads not otherwise listed as major roads in paragraph (A) of this rule. (4) When sudden failure of the dam would result in property losses restricted mainly to the dam and rural lands, and loss of human life is not probable, the dam may be placed in class IV. Dams which are twenty-five feet or less in height and have a total storage volume of fifty acre-feet or less may be placed in class IV. Class IV dams are exempt from the permit requirements of section 1521.06 of the Revised Code pursuant to paragraph (C) of rule 1501:21-19-01 of the Administrative Code. (B) All pertinent information including any unusual circumstances shall be considered by the chief in establishing an appropriate classification for a dam. Probable future development of the area downstream from the dam that would be affected by its failure shall be considered. Completed downstream hazard mitigation such as acquisition, removal or protection of downstream property may also be considered. However, the above criteria shall in no way preclude the chief’s requirement of greater safety in the interest of life, health, or property. Design Criteria Hydrologic: The magnitude of the design flood for each dam shall be set by the chief and determined from actual streamflow and flood frequency records or from synthetic hydrologic criteria based on current publications prepared by the division, the United States army corps of engineers, the United States geologic survey, the national oceanic and atmospheric administration, or others acceptable to the chief. The minimum design flood will be: (1) For class I dams, the probable maximum flood or the critical flood; (2) For class II dams, fifty percent of the probable maximum flood or the critical flood; and, (3) For class III dams, twenty-five percent of the probable maximum flood or the critical flood. Seismic: Seismic design criteria for dams are included in the general design requirements of paragraph (A) of Administrative Rule 1501:21-13-08. (A) The safety factors for the various elements of the dam shall conform to good engineering practice as approved by the chief. The safety factors and the design standards that are used by the applicant shall agree with the approved design assumptions. Jurisdiction/Powers of Department Sections 1521.06-064 of the ORC place the authority for implementation of the dam safety laws within the Division of Water of the Department of Natural Resources. Section 1521.06 requires that persons or governmental agencies desiring to construct certain dams must obtain a construction permit from the chief of the Division of Water. The Chief has the power to approve or disapprove an application. Sections 119.01 to 119.13 of the ORC give the Chief of the Division of Water the power to prescribe rules and regulations. Section 1521.062 of the ORC gives the Chief the power to call for remedial measures, as he deems necessary to safeguard life, health, or property. If the owner fails to perform such repairs, maintenance, remedial measures, or other measures within the required time period as may have been ordered by the chief, the chief has the right to cite noncompliance and seek judicial measures to have the structure removed or the deficiencies corrected at the expense of the owner. (Administrative Rules 1501:21-21-05). Permit/Approval Process Before a construction permit may be issued, three copies of the plans and specifications, including a detailed cost estimate, for the proposed construction, prepared by a registered professional engineer, together with a fee (graduated scale – based on the estimated cost of construction) and the bond or other security required by section 1521.061 of the ORC, shall be filed with the chief. The chief shall within 30 days from the date of the receipt of the application, fee, and bond or other security, issue or deny a permit for the construction or may issue a permit conditioned upon the making of such changes in the plans and specifications for the construction as the chief considers advisable if the chief he determines that the construction of the proposed dam would endanger life, health, or property. If the permit is denied, the bond or other security is returned to the applicant. After the construction is completed in accordance with the terms of the permit and the plans and specifications, the chief will approve the construction. One year later, if no evidence of non-compliance is evident, the bond is released (ORC 1521.06). As required by Section 1521.063 of the ORC, the owner is then required to pay an annual fee to the Division based on the classification and size of the dam. Owners of prepermit, Class I, II, and III dams must also pay an annual fee. Required spillway design standards are found in the Administrative Rules Section 1501:21-13-03 through -05. Dam construction, including remedial work, is to be paid for by the owner (Administrative Rules 1501:21-21-05). Repair, Improvement, Alteration, or Removal Before commencing the repair, improvement, alteration, or removal of a dam or levee, the owner shall file an application including plans, specifications, and other required information, and shall secure written approval of the application by the Chief. Emergency actions by the owner required to safeguard life, health, or property are exempt from this requirement (ORC 1521.062 F). Fees Fees on a graduated scale, based on estimated construction costs, are required to obtain construction permits. Owners of pre-permit, Class I, II, and III dams must also pay an annual fee based on dam classification and size. Inspection Process Pursuant to Section 1521.062 of the ORC, periodic inspections will be made by the chief of all class I, II, and III dams to ensure that continued operation and use of the dam does not constitute a hazard to life, health, or property. The chief may make, as deemed necessary, periodic inspections of Class IV dams (Administrative Rules 1501:21-21-01). Section 1521.064 of the ORC provides for the exemption of certain dams from inspection if they meet specific criteria established by the Division of Water. The Rules do not specify any inspection fees to be paid by the owner. An operation, maintenance and inspection manual is required for all Class I, II and III dams. The manual will include a program for regular inspection, maintenance, and monitoring by the owner or operator (Administrative Rules 1501:21-15-06). An emergency action plan is required for all class I, II and III structures. The emergency action plan for all class I structures shall include but not be limited to an inundation map of the critical routing reach. An inundation map may also be required for class II and III dams as designated by the chief. The required detail of this map depends upon the complexity of the downstream hazard and shall be acceptable to the chief. (Administrative Rule 1501:21-15-07) The owner is required to have a licensed, professional engineer perform all inspections (Administrative Rules 1501-21-3-02). The chief may make inspections during construction as deemed necessary to insure that the structure is being built in compliance with the approved plans and specifications (Administrative Rules 1501:21-17-01). Frequency of Inspections Hazard Classification Inspection Cycle High Not to exceed 5 years Significant Not to exceed 5 years Low Not to exceed 5 years Violations/Penalties If the owner fails to perform repairs, maintenance, remedial measures, or other measures as mandated by the chief, the chief shall so notify the owner of the noncompliance and of the chief's intention to remove or correct the unsafe structure, at the expense of the owner, pursuant to section 1521.062 of the ORC. Such cost is a lien upon such lands from the date of entry and shall be collected as other taxes and returned to the division (Administrative Rules 1501:21-21-05). Section 1521.99 of the ORC establishes penalties for violations of Section 1521.06 and 1521.062. Emergencies The chief of the Division of Water is empowered to take charge of a dam safety emergency to protect life, property, and health. If the condition of any dam is found, in the judgment of the chief, to be so dangerous to the safety of life, health, or property as not to permit time for the issuance and enforcement of an order relative to repair, maintenance, or operation, the chief shall employ any of the following remedial means necessary to protect life, health, and property. (1) Lower the water level of the lake or reservoir by releasing water; (2) Completely drain the lake or reservoir; (3) Take such other measures or actions as the chief considers necessary to safeguard life, health, and property. The chief shall continue in full charge and control of the dam or levee until the structure is rendered safe. The cost of the remedy shall be recoverable from the owner of the structure by appropriate action in a court of competent jurisdiction. Liability Pursuant to the provisions of section 1521.062 of the ORC, the owner of a dam shall be responsible for the continued safe operation and use of the structure so that it does not constitute a hazard to life, health, or property. In the interest of safeguarding life, health, or property, the chief may require the owner to prepare a written manual detailing the operation, maintenance, and inspection procedures necessary for the continued safe operation of the dam (Administrative Rules 1501:21-21-04). Oversight All orders of the chief are subject to appeal pursuant to sections 1521.06, -.062, and 119.01 to 119.13 of the ORC. Filing of an appeal does not automatically stay the effectiveness of the orders of the chief (Administrative Rules 1501:21-23-01). Miscellaneous The following dams are exempt from the construction permit requirement (Administrative Rules 1501:21-19-01): • Dams constructed under Chapter 1513 ORC (coal mine impoundments). • Dams, regardless of height, which have a storage capacity of not more than 15 acrefeet. • Dams less than 10 feet in height, with a storage capacity of not more than 50 acrefeet. • Dams designed and constructed by the United States Army Corps of Engineers. • Dams constructed by the state of Ohio, Department of Natural Resources. • Dams placed by the chief in class IV under rules 1501:21-13-01 of the Administrative Rules. • Modifications or repairs to existing dams provided that the modifications or repairs do not constitute an enlargement to the structure as defined under rule 1501:21-3-01 of the Administrative Rules. Other Publications • An Operation, Maintenance, and Inspection Manual • Guidelines for Developing EAPs and Operation and Maintenance Manuals • Dam Safety Related Fact Sheets (available on Ohio Web Page): Lake Drains, Rodent Control, Trees and Brush, Classification, Failures, Seepage, Concrete Repair Techniques, Inspection of Concrete Structures, Construction Permits for Dams, Design and Maintenance of Trashracks, Probable Maximum Flood, Annual Fee, Construction Permits for Levees, Open Channel Spillways (Earth and Rock), Inspection Exemption, Embankment Instabilities, Ground Cover, Open Channel Spillways (Concrete Chutes and Weirs), Outlet Erosion Control Structures, Upstream Slope Protection, Spillway Conduit System Problems, Problems with Concrete Materials, Problems with Metal Materials, Problems with Plastic Materials, Critical Flood Guidelines, Remediation Alternatives. • Dam and Levee Construction Related Forms: Application for a Permit to Construct a Dam, Dike or Levee in the State of Ohio Instructions for Application for a Permit to Construct a Dam Dike or Levee in the State of Ohio Preliminary Design Report Requirements 1501:21-05-02 Revised Construction Permit Filing Fees Performance Bond State Web Site: http://www.dnr.state.oh.us/water ODNR Home | Jobs | Contact ODNR ODNR Division of Soil and Water Resources - Publications, Maps & Data Search Home | Contact Us | Offices/SWCD | Well Logs | Watersheds | Education | Programs | Publications & Data Publications (all) Maps (all) Data Mailing Address: ODNR Division of Soil & Water Resources 2045 Morse Road, B- 2 Columbus, Ohio 43229-6693 Contact Us Fact Sheets (all topics) Newsletters & Reports Stream Management Guide Fact Sheets Nonpoint Source Pollution Investigations Flood Maps Ground Water Resource Maps Pollution Potential Maps Potentiometric Surface Maps Statewide Aquifer Maps Well Log Filing Well Logs Searches GIS Data Observation Well Data Fact Sheet Index by Program Area Subject Area No. Title Content Description Revision Date Canals 4 The Ohio Canal System ODNR canal history, laws, administration, public benefits Aug/5/92 Canals 41 Ohio & Erie Canal/Hydraulic Operations History & details of canal lakes and diversions with flow diagrams March/28/97 Conservation 1 Water Efficiency at Home Household water saving devices and methods Dec/18/06 Conservation 2 Water Efficiency in Your Own Back Yard Yard, plants, and lawn watering methods Jul/2/92 Dams 26 Dam Safety: Lake Drains Definition, Types, Use, Maintenance of lake drains July/28/99 Dams 27 Dam Safety: Rodent Control Rodent damage to dams and control measures Sept/17/08 Dams 28 Dam Safety: Trees and Brush Damage to dams from trees and brush, proper maintenance Feb/08/02 Dams 29 Dam Safety: Classification Classification of dams in Ohio July/06/04 Dams 30 Dam Safety: Failures Cause of earthen dam failures Jun/22/94 Dams 31 Dam Safety: Seepage Detection, control, and monitoring of seepage through dams Jun/22/94 Dams 32 Dam Safety: Concrete Repair Techniques Techniques for repair of deteriorated concrete structures July/28/99 Dams 33 Dam Safety: Inspection of Concrete Structures Inspection of concrete structures for dams July/28/99 Dams 34 Dam Safety: Construction Permits for Dams What structures require permits and how to apply Jun/22/94 Dams 37 Dam Safety: Probable Maximum Flood Estimate methodology and implications of floods on dam design April/7/95 Dams 38 Dam Safety: Design and Maintenance of Trashracks Trashrack design considerations for pipe and riser spillways July/20/95 Dams 39 Dam Safety: Annual Fee How to calculate the annual dam safety fee June/09/2010 Dams 48 Dam Safety: Construction Permits for Levees Which levees require permits and how to apply Dec/13/06 Dams 49 Dam Safety: Open Channel Spillways (Earth and Rock) Design rules, materials, and maintenance issues July/28/99 Dams 51 Dam Safety: Outlet Erosion Control Structures (Stilling Basins) Methods of protecting spillway outlets from erosion Feb/29/99 Dams 52 Dam Safety: Upstream Slope Protection Methods of protecting the upstream slope of a dam from wave erosion July/28/99 Dams 53 Dam Safety: Embankment Instabilities Detection and repair of cracks, slides, and depressions July/28/99 Dams 54 Dam Safety: Ground Cover Establishing and maintaining proper vegetation on dams July/28/99 Dams 55 Dam Safety: Spillway Conduit System Problems Monitoring and repair of spillway conduit systems July/28/99 Dams 56 Dam Safety: Problems with Concrete Materials Monitoring of concrete structures July/28/99 Dams 57 Dam Safety: Problems with Metal Materials Monitoring and controlling corrosion of metals March/24/01 Dams 58 Dam Safety: Problems with Plastic (Polymer) Materials Inspection and monitoring of plastics July/28/99 Fact Sheet Descriptions and Index Page 1 of 3 http://www.dnr.state.oh.us/water/pubs/fs_div/fstindex/tabid/4153/Default.aspx 11/26/2010 Dams 59 Dam Safety: Open Channel Spillways (Concrete Chutes and Weirs) Design, maintenance, and monitoring of concrete chutes and weirs July/28/99 Dams 60 Dam Safety: Critical Flood Design Criteria Lowering Your Dam's Design Flood Using Critical Flood Analysis Nov/04/99 Dams 61 Dam Safety: Inspection Exemption Criteria, and Procedures to Apply for an Inspection Exemption Jan/29/01 Dams 63 Dam Safety: Remediation Alternatives Options for dam owners who failed to acquire construction permits or modify the dam to meet code. May/20/02 Flood 12 Floods and Flood Damage Prevention Ohio flood history, regulatory goals, floodplain definitions July/02/02 Flood 13 Facts About Flood Insurance National Flood Insurance Program benefits/participation July/02/02 Flood 21 How to Obtain Flood Maps Producer, distributors, types of, IDs of, costs, how to pay July/08/02 Flood 36 Facts About Floodproofing (NOT AVAILABLE) Damage costs, methods, structures, national insurance standards N/A Flood 40 Post?Disaster Floodplain Management Post flood preventive and recovery issues for floodplain managers July/08/02 Flood 42 Community Rating System and Flood Hazard Mitigation Reduce flood insurance rates through CRS qualifying activities Oct/14/97 Flood 50 Natural Benefits of Floodplains Why floodplains are valuable... April/11/05 Flood 66 Understanding Your Flood Risk How to interpret risk in FEMA Special Flood Hazard Area Feb/15/08 Ground Water 9 Evaluating Ground Water Pollution Potential in Ohio GWPP mapping program, methods, uses, status map Jan/12/04 Ground Water 10 Ground Water Resources Mapping in Ohio GWR mapping methods, uses, description of program, status Jan/12/04 Ground Water 20 Ground Water Level Monitoring in Ohio Well network history, uses annual cycles, influences on Jan/8/93 Ground Water 24 What's Ground Water? Terms defined, GW occurrence, aquifer differences in Ohio Oct/20/93 Ground Water 43 Surface Water and Ground Water Interaction Relationships between surface and ground waters June1/95 Ground Water 44 What is Nonpoint Source Pollution Defines terms, problems, and processes of NPS pollution June1/95 Ground Water 45 Individual Practices to Protect Ground Water Quality How you can help protect your water quality June1/95 Ground Water 47 Ground Water Quality Water quality of naturally occurring aquifers June1/95 Ground Water 65 Potentiometric Surface Mapping in Ohio Defines P-Surface Maps, their Production and Use July 1/05 Planning 22 Community Water Supply Planning in Ohio Past, future, current study plans, need for ongoing planning Oct/15/93 Planning 25 Ohio's Conservancy Districts Ohio district addresses, history, functions March/07/07 Services of 17 Services of the Ground Water Resources Section Description of publications and technical assistance Jan/8/93 Water Cycle 18 The Hydrologic Cycle Earth's water movement through sea, land & air Sep/2/93 Water Cycle 11 Precipitation in Ohio Annual and Long Term Precipitation Trends Oct/15/92 Wells 3 Water Efficiency for Private Well Owners Private well construction/management/maintenance July/2/92 Wells 5 Well Abandonment Regulations ODH and Ohio EPA Well abandonment regulations July/22/02 Wells 6 Properly Sealing Unused Wells Well sealing benefits and methods Dec/16/92 Wells 7 What is a Well Screen? Well screen defined, use, benefits, selection Jan/8/93 Electronic storage & retrieval of well log Fact Sheet Descriptions and Index Page 2 of 3 http://www.dnr.state.oh.us/water/pubs/fs_div/fstindex/tabid/4153/Default.aspx 11/26/2010 ODNR Home | News | Regulatory Policy | Privacy Statement | ODNR Employees | Contact ODNR Wells 8 Well Log Computerization data & images Sep/5/92 Wells 14 Well Construction Materials and Techniques Casing types, depth, regulations, geologic considerations Dec/16/92 Wells 15 Before You Have a Well Drilled Geologic, construction & contractor considerations Dec/16/92 Wells 16 How to Read Well Log and Drilling Reports Detailed explanation of well log elements Dec/31/93 Wells 19 Dry Driven Grout Method Methods of grouting cable tool drilled wells Nov/23/93 Wells 23 When Does a Well Log Need to be Filed? Well defined, types of wells, info required, laws, penalties Oct/1/93 Wells 35 Low Yielding Wells Household water needs & how to meet them w/low yield well Jan/9/95 Wells 46 Well Construction in a Buried Valley Well construction techniques for buried valley aquifers June1/95 Wells 62 Understanding Your Water Well Terms and procedures regarding construction, use and maintenance July/03/01 Wells 64 Using GPS for Well Location on Well Logs How to fill in the Geographic Coordinates on a Well Log and Drilling Report from GPS readings Feb/03/03 General Questions | Website Comments/Questions Fact Sheet Descriptions and Index Page 3 of 3 http://www.dnr.state.oh.us/water/pubs/fs_div/fstindex/tabid/4153/Default.aspx 11/26/2010 DIVISION OF WATER OHIO DEPARTMENT OF NATURAL RESOURCES Ohio Department of Natural Resources Division of Water Fact Sheet Fact Sheet 95–37 Continued on back! Uncontrolled flood waters are one of the most powerful and destructive forces in nature. Dams that are not designed to withstand major storms may be destroyed by them, increasing flood damage downstream. This damage is too often catastrophic. In order to protect lives and property downstream, the Ohio Administrative Code requires that dams be constructed to safely handle an appropriate percentage of the Probable Maximum Flood (PMF). This percentage varies according to the height of the dam, size of the impoundment, and extent and severity of damage possible upon failure. The requirements established in Ohio are similar to those used in other states, and historical records of significant storms and dam failures this century verify that the design criteria are reasonable. Definitions The Probable Maximum Precipitation (PMP) is the greatest depth (amount) of precipitation, for a given storm duration, that is theoretically possible for a particular area and geographic location. The Probable Maximum Flood (PMF) is the flood that may be expected from the most severe combination of critical meteorological and hydrologic conditions that are reasonably possible in a particular drainage area. Historical Storms in Ohio and Dam Failures Storms which have caused severe flooding and included precipitation amounts that reached a significant percentage of the PMP have occurred in Ohio this century. Flood waters from these storms caused the failure of dams and other structures. Many dam failures are considered disasters because they cause great harm, damage, or serious and sudden misfortune. Because of the rapid and unexpected manner in which dam failures can occur, they are judged to be as serious as earthquakes and tornadoes. A storm approaching two thirds of the PMP struck north-central Ohio in the summer of 1969. Some small areas within the region were inundated with 14 inches of rain in 12 hours. Three large dams and many small farm-pond dams failed. Almost all the failures were caused by water overtopping the dams. Dam Safety: Probable Maximum Flood In 1990, severe flash floods destroyed eighty residences near the town of Shadyside in southeast Ohio. Twenty six people died. In this instance, the amount of precipitation did not constitute a high percentage of the PMP, yet the flood waters which resulted were deep and powerful. The potential for damage due to dam failures is increasing along with the increase of residential and commercial development downstream of dams. In many cases, existing dams will need to be modified to keep downstream areas safe from disaster. Recent Notable U.S. Dam Failures Year Name Location Deaths Damage 1972 Buffalo Creek Dam West Virginia 125 $400 million 1972 Canyon Lake Dam South Dakota 139 $60 million 1976 Teton Dam Idaho 11 $400 million 1977 Taccoa Falls Dam Georgia 39 $30 milllion 1982 Lawn Lake Dam Colorado 3 $21 million Classification of Ohio Dams Dams in Ohio are divided into four classes based on the storage volume of the impoundment, dam height and potential downstream hazard (how far downstream the residences are, etc.). These criteria were chosen because they affect the extent and severity of downstream damage possible upon failure. The percentage of the PMF that a dam must be designed to withstand depends upon its classification. Dams that could cause loss of human life if they fail must be designed to handle 100 percent of the PMF. More details about the classification system can be found in the Ohio Administrative Code and Fact Sheet No. 94-29. Development of the PMP Scientists use both meteorological methods and historical records to determine the greatest amount of precipitation which is theoretically possible within a region. The historical data consists of point precipitation amounts measured at rain gages throughout the region being studied, or a region with very similar meteorologic and topographic characteristics. These rainfall data are subsequently maximized through "moisture maximization" and other numerical methods. Moisture maximization Ted Strickland Governor • Sean D. Logan Director • Deborah Hoffman Chief I 04/04/95 is a process in which the maximum possible atmospheric moisture for a region is applied to rainfall data from a historic storm. This process increases the rainfall depths, bringing them closer to their potential maximum. Probable maximum precipitation amounts vary slightly throughout Ohio because of variations in topography and meteorology. The PMP is greatest in the southern portion of the state. Furthermore, not all storms have the same duration. Using the methods mentioned above, the PMP has been determined for different storm periods, generally ranging from six to seventy two hours. Development of the PMF The Probable Maximum Flood is the flood which is a direct result of the Probable Maximum Precipitation. However, drainage areas with the same PMP may have different PMFs. This is possible because the amount of flooding which results from a given rainfall amount depends upon the characteristics of the drainage basin. For this reason, the PMF, not the PMP, must be used as a design criterion for a dam. Some important characteristics include soil type, land use, size and shape of the watershed, and average watershed slope. Both the volume and rate of runoff are affected. For example, water will run off of steep slopes more quickly than gentle ones. More water will infiltrate sandy soils than clay. Any other questions, comments concerns, or fact sheet requests, should be directed to the Division of Water at the following address: All-season Probable Maximum Precipitation (in inches) for 6-hour duration, 10-square mile area. Canada USA Lake Erie .1 .2 .3 .4 25.5 .6 .7 .8 .9 26.0 .1 .2 .3 .4 26.5 .6 .7 .8 .9 27.0 .1 .2 .3 .4 27.5 .6 .7 .8 .1 .2 .3 25.5 .4 .6 .7 .8 .9 26.0 .1 .2 .3 .4 26.5 .6 .7 .8 .9 27.0 .1 .2 .3 .4 27.5 .6 .7 .8 Ashland Defiance Henry Wood Ottawa Williams Fulton Lucas Sandusky Paulding Putnam Hancock Seneca Huron Erie Lorain Cuyahoga Medina Summit Portage Mahoning Trumbull Geauga Lake Ashtabula Richland Wayne Stark Columbiana Carroll Holmes Tuscarawas Knox Coshocton Harrison Guernsey Belmont Muskingum Licking Crawford Morrow Delaware Franklin Mercer Auglaize Shelby Logan Darke Miami Champaign Hardin Wyandot Madison Union Marion Clark Preble Montgomery Greene Fayette Pickaway Butler Warren Clinton Ross Hamilton Highland Pike Scioto Adams Fairfield Perry Morgan Noble Monroe Washington Athens Vinton Jackson Meigs Gallia Lawrence Jefferson Van Wert Allen Brown Hocking Clermont Adapted from HMR– 51, National Weather Service, 1978. Ohio Department of Natural Resources Division of Water Dam Safety Engineering Program 2045 Morse Road Columbus, Ohio 43229-6693 Voice: (614) 265-6731 Fax: (614) 447-9503 Website: http://www.dnr.state.oh.us/water DIVISION OF WATER OHIO DEPARTMENT OF NATURAL RESOURCES Ohio Department of Natural Resources Division of Water Fact Sheet Fact Sheet 99–60 Dam Safety: Critical Flood Design Criteria Continued on back! hazard, drainage area, and downstream topography are such that traditional flood design standards do not accurately account for the downstream hazard, critical flood criteria allow for a reduction of up to 60% of the design flood. For example, let’s look at a Class I dam. This type of dam is required to safely pass the 100% PMF through its spillway system without endangering the safety of the dam. As rain falls onto a dam’s watershed, some of the rainfall will infiltrate into the ground, some will evaporate, and most of it will runoff across the ground into the pond or lake. The water level in the impoundment will begin to rise while simultaneously flowing through the dam’s spillway(s). As water exits the dam’s spillway(s), the downstream channel will begin to fill and flow accordingly. For most dams, the downstream channel will likely fill with some water, but most of the water flows downstream without backing up significantly. For those few cases where the downstream channel fills rapidly to the point where water rises dramatically and failure of the dam would have no additional significant increase in elevations of floods downstream, the design flood can be reduced. In other words, there may be a point, say 50% of the PMF (the critical flood in this case), where designing for additional flood capacity for the dam is no longer reasonable. If the dam were to fail, the downstream hazard would not be further adversely effected. In this case, the spillway system may be designed for half of what it would have been originally designed, therefore saving dollars without increasing the hazard to the downstream area. What is the Maximum Reduction in Design Flood? The design flood can be reduced approximately up to 60% for each class of dam: Class I 100% PMF down to no less than 40% PMF Class II 50% PMF down to no less than 20% PMF Class III 25% PMF down to no less than 100 Year Ohio’s Dam Safety Rules require dams to pass floods through their spillways without endangering the safety of the dam. The magnitude of the design flood is directly related to the classification of the dam - which in turn is related to the dam’s downstream hazard and/or the dam’s height. The greater the downstream hazard, i.e., loss of human life, high-value property, etc., the larger the design flood. Definitions The probable Maximum Precipitation (PMP) is the greatest depth (amount) of precipitation for a given storm duration, that is theoretically possible for a particular area and geographic location. The Probable Maximum Flood (PMF) is the flood that may be expected from the most severe combination of critical meteorological and hydrologic conditions that are reasonably possible in a particular drainage area. Classification of Ohio Dams Dams in Ohio are divided into four classes based on the storage volume of the impoundment, dam height, and potential downstream hazard (how far downstream residences, businesses are, etc.). More details about the classification system can be found in the Dam Safety: Classification of Structures Fact Sheet No. 94-29. Critical Flood Design Criteria Specific guidelines are available for preparing a critical flood engineering analysis. This analysis must be performed by a professional engineer licensed in the State of Ohio. The guidelines can be downloaded from the Division of Water’s world wide web site, (http://www. dnr.state.oh.us/odnr/water/temp/dartrlsa.html), or you can request a copy by calling our office directly. Could the Critical Flood Analysis Make a Difference for My Dam? The critical flood criteria were developed to make Ohio’s Dam Safety Rules more flexible in recognizing that some dams fall outside of the typical parameters used in designing spillway capacity. Specifically, for those circumstances where the size of the dam, its downstream Ted Strickland Governor • Sean D. Logan Director • Deborah Hoffman Chief What Factors Should I Consider Before Proceeding With an Analysis? The cost of the analysis can be thousands of dollars. Let’s assume that a dam inspection by our engineers reveals that a dam is deficient in its ability to pass the design flood. It would be beneficial to have an analysis performed if the design flood was reduced enough so that the spillway system did not need to be upgraded or replaced. Let’s assume that upgrading the spillway system costs $50,000. If the cost of the critical flood analysis was $5,000, the cost of the critical flood analysis would be warranted. Sometimes it can be straightforward to predict whether or not an analysis would be beneficial. However, in those cases where it may not be clear, other options should be considered. For example, if room exists in one of the dam’s abutments to excavate an emergency spillway or perhaps enlarge an existing emergency spillway, it may be more cost effective to do so. There is always a risk in running an analysis and finding out that the reduction in design flood is insignificant and the spillway system enlargement is still required. A critical flood analysis approved by our office means that a reduced design flood is acceptable for your dam. Please note that a reduction in the design flood for your dam may increase the risk of failure or damage to your dam. This could result in an economical burden on the dam owner. This risk should be closely considered! How Can I Apply for the Critical Flood Reduction? A request for consideration must be submitted to the Chief of the Division of Water. The request must be accompanied by supporting calculations based upon an analysis performed by a professional engineer registered in the State of Ohio. The engineer’s analysis must conform to the critical flood guidelines provided by the Division of Water. Before applying, it is best to call and speak with an engineer in the Division’s Dam Safety Engineering Program. What Restrictions Are There? A critical flood reduction based upon planned evacuation, probability of inhabitation, or monetary recovery of property damage will not be considered. In other words, guaranteeing that a downstream residence or business will be evacuated during a dam failure will not be considered. In situations where the downstream hazard may or may not be inhabited, such as in the case of a campground, rental property, hotel, and so forth, the probability of inhabitation will not be considered. Also, understanding that failure of a dam will damage downstream property and guaranteeing that the damages will be paid for will also not be considered. Finally, if the downstream hazard were to change, the critical flood exemption could be nullified. Any other questions, comments concerns, or fact sheet requests, should be directed to the Division of Water at the following address: I 11/04/99 Ohio Department of Natural Resources Division of Water Dam Safety Engineering Program 2045 Morse Road Columbus, Ohio 43229-6693 Voice: (614) 265-6731 Fax: (614) 447-9503 Website: http://www.dnr.state.oh.us/water Critical Flood Guidelines Purpose of the $critical flood# rule is to recognize that in certain situations, overtopping dam failures may be insignificant in how much damage they cause to downstream areas. It is based on the assumption that if all downstream flood damages occur due to a base-flow flood that is less than the regulatory design flood for the dam, then requiring additional spillway capacity above this flood to satisfy the design flood requirement would therefore, not be necessary. For this outcome, a flood of lesser size may exists that would show a more measurable impact than the regulatory design flood for the dam. The measurable impact that occurs to downstream areas from any hypothetical base-flow flood, given the dam fails, must be greater than the amount occurred for the same flood, given the dam does not fail, before the flood can be labeled as critical. The term $base-flow# flood, used throughout this document, refers to a starting flood condition in which an action or undertaking is made and should not be misinterpreted as groundwater flow. The importance as to the dam s value and benefits it provides to the owner and the community must always be evaluated before subjecting the dam to possible overtopping and failure by a flood that is less than the required design flood for the structure. An incremental damage analysis may be used to determine the inflow design (critical) flood that is less than the minimum requirements of 1501:21-13-02. The flood will be based upon a comparison of two flood simulations occurring with the dam in question present: one, a base-flow flood that has a size that would cause failure of the dam, but has been modeled without any effects from a dam failure (Condition A), two, the same flood, but modeled to include the dam-break discharges based on the most severe hypothetical dam failure that is possible (Condition B). These flood simulations are routed downstream through a reach that has been determined to be the recipient of the potential floodwater damages. The spillway capacity and inflow design flood will be acceptable where it can be shown that the dam failure flood (Condition B) would cause no expected additional loss of life and would not cause significant incremental flood damages downstream of the dam. Additional potential for loss of life, health or property in the critical routing reach is expected if the incremental depth of flow between the dam failure and non-failure floods is greater than 2.0 feet or the product of the average floodplain flow velocity and the incremental depth is greater than 7.0 feet^2/second. The design for the critical flood must be for specific site conditions and based on a quantitative and relative impact analysis of the downstream critical routing reach. The owner must submit to the chief, in writing, a request for consideration of the critical flood as the design flood. This request must be accompanied by appropriate supporting calculations. The chief will not consider risk assessment based upon planned evacuation, probability of inhabitation, or monetary recovery of property damage. The scope of the critical flood analysis will identify the flooding source, upstream and downstream limits of the stream reach to be studied, and the applicable hydrologic and hydraulic methodology to be used. The scope may require completion of any or all of the following work items: Critical Flood Guidelines Page 2 I. Field surveys to obtain data for stream and adjacent floodplain cross sections and other structures that may affect the hydraulics of the study reach. II. Hydrologic analyses to determine stream peak discharges for the dam s design flood and any floods of a lesser magnitude used in the process of determining the inflow design flood for the dam. III. Hydraulic analyses to determine dam failure discharges, flood elevations and floodplain stream and channel velocities at critical locations along the study reach. IV. Development of a flood inundation map for the critical structures within the study reach using topographic work maps of the floodplains. General Requirements: 1. A critical flood study conducted in accordance with Ohio Administrative Code (OAC) Rule 1501:21-13-02 shall include a written statement of purpose and scope of the analysis. 2. The analysis shall identify the flooding source, recurrence intervals for all flood events that were analyzed, upstream and downstream limits of stream reach to be studied, and the applicable hydrologic and hydraulic methodology to be used. This scope of the study may include, but not be limited to, completion of any or all of the following work items: a. Preparation of topographic work maps of the floodplains within the study area. The maps must identify elevations of the critical structures that are affected by the flood study. b. Field surveys to obtain data for stream cross sections and other hydraulic parameters (i.e., Manning s $n#, Expansion and Contraction coefficients, etc.). c. Hydrologic analysis to determine discharge rates used in flood routings for the various flood frequencies used to substantiate the critical flood flows. d. Hydraulic analysis to determine dam failure discharges, flood elevations, floodplain boundaries, and stream channel and floodplain velocities. Calculations to determine the dam failure discharges must include a sensitivity study on the set of boundary conditions established for the dam breach analysis. This study is required for obtaining the most severe hydraulic condition during a catastrophic dam failure that is theoretically possible. Dam breach parameters used in the critical flood analysis shall be based on suggested values established by the U. S. Army Corps of Engineers, or the Federal Energy Regulatory Commission, unless otherwise approved by the chief. Critical Flood Guidelines Page 3 e. Compilation of other flood study technical documentation used in the analysis. f. Preparation of a critical flood report with flood profiles and work maps of the floodplain. 3. A $critical flood# study conducted in accordance with OAC Rule 1501:21-13-02 shall be completed under supervision of a registered professional engineer who is qualified to do flood study work. Data Acquisition and Mapping 1. Topographic mapping for critical flood studies conducted in accordance with OAC Rule 1501:21-13-02 shall conform to the following standards: A. Mapping shall be done by photogrammetric methods and/or topographic surveying. If topographic mapping is based solely on field surveys, map accuracy requirements shall be the same as those required by photogrammetric methods. B. Map scale may vary but should not exceed one inch equals 1000 feet for the study area. C. Contour intervals shall not exceed 5 feet for the appropriate terrain. Intermediate onefoot contour intervals may be required for special cases such as unusually flat terrain. D. Elevations used in the flood study shall correspond to the National Geodetic vertical datum of 1929 or, when available, the successor North American vertical datum of 1983. Elevation reference marks and temporary reference points established for the study shall be tied by survey to at least one official bench mark of the datum for which the exact elevation to the nearest hundredth of a foot has been obtained. Data Standards and Procedures 1. The following standards and procedures shall apply to hydrologic data used in a critical flood determination study conducted in accordance with OAC Rule 1501:21-13-02. A. Hydrologic data shall be from official government sources except as approved by the chief. Use of unofficial data sources, such as high-water marks, shall be dependent on reliability of the data. B. Stream flow data used for calibrating the hydrologic model shall be from official government records such as published by the United States Geological Survey. Critical Flood Guidelines Page 4 C. Precipitation data shall be from official government records such as published by the National Weather Service. D. Watershed data shall be from official maps, survey documents, and aerial photography generated by pertinent government agencies. Sufficient field observations shall be made to interpret maps and photographs and identify any significant changes in watershed conditions since source materials were completed. 2. The following standards and procedures shall apply to channel and valley cross sections used in the critical flood study conducted in accordance with OAC Rule 1501:21-13-02: A. Each cross section must span the entire floodplain for each of the appropriate discharges used in the flood study. The cross sections must represent the particular stream reach from which it was taken. Local irregularities in ground surface that are not representative of reaches shall be avoided in surveys. B. Cross-section alignment shall be perpendicular to the direction of flow. Crosssections may consist of straight, curved or zigzag segments as needed to achieve proper alignment. C. Horizontal stations for the cross-section shall correspond to the distance measured to the nearest foot along the straight, curved or zigzag alignment of the cross-section. D. Cross-section elevations shall be determined at all significant breaks in ground slope and at points where significant changes in hydraulic characteristics of the floodplain occur. Additional points shall be included, as appropriate, using the following criteria as a guide: 1. The distance between channel reach stations should be such that the depth of flow at the next neighboring cross-section downstream does not increase more than 20 percent. 2. No adjacent horizontal points in the overbank areas shall be separated by more than 10 percent of the complete valley and channel cross-section width. 3. No adjacent horizontal points in the main channel shall be separated by more than 20 percent of the main channel width or 2 feet, whichever is greater. 4. Elevations of above water portions of cross-sections shall be determined by field surveys or photogrammetric techniques, when reliable data of sufficient accuracy cannot be obtained from available sources. Elevation of below water portion of cross- Critical Flood Guidelines Page 5 sections shall be determined by field survey except where reliable data of sufficient accuracy can be obtained from available sources. Field surveys shall normally be accomplished by differential leveling or a differential global positioning system. 3. The following standards and procedures shall apply to channel and overbank reaches used in the critical flood analysis conducted in accordance with OAC Rule 1501:21-13-02: A. Channel reach length shall be the distance between cross sections as measured along the principal flow line of the stream channel at the flood stage. B. Channel and overbank reach lengths between stream cross-sections shall be determined by field surveys or distance measurements on topographic work maps. Design drawings for bridges and hydraulc structures shall be used to obtain reach lengths if available. 4. The following standards and procedures shall apply to roughness coefficients used in the critical flood analysis conducted in accordance with OAC Rule 1501:21-13-02: A. Roughness coefficients shall be determined by field inspection of channel and overbank areas. Consideration shall be given to variation in roughness at various flood stages. Aerial photographs, when available, shall be used to supplement field observations. B. Roughness coefficients obtained from any previous work shall be field checked for accuracy and updated, if they do not reflect current conditions. 5. The following standards and procedures shall apply to bridges and hydraulic structures data used in the critical flood analysis conducted in accordance with OAC Rule 1501:21-13-02: A. Dimensions and elevations of all bridges and hydraulic structures including below water sections shall be obtained from construction drawings and/or by field survey measurements. B. Bridges and hydraulic structures data obtained from documents shall be field checked in sufficient detail to verify that the data are for the correct structure and match asbuilt conditions. C. No dimensions or elevations for bridges and hydraulic structures shall be determined by photogrammetric methods. Photographs shall be used to supplement and document field observations or hydraulic structures. 6. The following standards and procedures shall apply to the dam failure analyses data used in Critical Flood Guidelines Page 6 the critical flood study conducted in accordance with OAC Rule 1501:21-13-02: A. All boundary conditions used in the dam failure analysis must be supported by sound engineering assumptions and supporting field data obtained for the dam. A sensitivity analysis shall be required by varying the input boundary conditions used in a dam break model as a means of converging on the worst case dam failure modeling scenarios. The maximum discharges obtained from the dam failure analysis shall be used for the basis of determining downstream impact on the critical routing reach. B. Parameters used to estimate the erosiveness of the soils shall be field checked in sufficient detail to verify their validity in use. Each boundary condition used in the development of the dam failure model shall be supported by sound engineering assumptions. Hydrologic Requirements 1. Hydrologic analyses for the critical flood determination conducted in accordance with OAC Rule 1501:21-13-02 shall require a determination of the base-flow flood discharges and dam failure discharges at appropriate stream stations downstream of the dam. The criteria used to establish the initial base-flow flood discharge for a class I dam is the probable maximum flood, for a class II dam, 50 percent of the probable maximum flood, and for a class III dam, 25 percent of the probable maximum flood. The dam failure discharges are determined by doing a breach analysis for the dam and combining the resulting breach hydrograph for the worst case failure condition with the base-flow flood hydrograph established for the dam. A. Flood peak discharge estimates shall be determined for the downstream terminus of the stream reach studied and at all upstream stations where significant changes in peak discharge occur due to reduction in tributary drainage area and other factors. B. Flood peak discharge estimates established for the study area by previous work shall be acceptable for use in flood studies provided that parameters used to make previous estimates remain valid for existing conditions, methodologies are consistent with standard engineering practices and guidelines, and accuracy of estimate is within confidence limits approved by the chief. 2. Methodology for calculating discharges conducted for critical flood analyses in accordance with OAC Rule 1501:21-13-02 shall conform to the following standards: A. A rainfall-runoff model (e.g., HEC-1) shall be used to estimate the flood peak discharges used in the critical flood analysis. The model shall be calibrated as Critical Flood Guidelines Page 7 appropriate and conform to the following standards: 1. Models shall normally be based on unit-graph theory as embodied in unit-graph procedures of the Natural Resources Conservation Service, United States Geological Survey, and United States Army Corps of Engineers. Use of an alternate runoff simulation modeling procedure must be approved by the chief. 2. Drainage areas and sub-basin areas for unit graphs shall have reasonable uniform hydrologic characteristics. 3. Durations of storm rainfall shall be the duration resulting in the largest discharges for the stream reach being studied. 4. Rainfall amounts for storm events of different duration and frequency shall be estimates as published by the National Weather Service or other approved source. 5. Point-Rainfall estimates shall be adjusted using area-depth relationships when the area of the modeled drainage basin exceeds ten square miles. 6. Rainfall distribution shall be an appropriate pattern such as national weather service median time distributions, miller distribution, or Natural Resources Conservation Service Type II storm pattern. 7. Methodology used to estimate flood peak discharges shall include procedures that account for urbanization, surface mining, regulation, and valley storage when these are significant factors affecting flood flows. Urbanization and surface mining shall be considered to be significant factors whenever more than 30 percent of the watershed is affected by these land use activities. Allowances for effects of urbanization on flood peaks shall be made by appropriate procedures such as those developed by the United States Geological Survey and the Natural Resources Conservation Service. Effects of Regulation and Valley Storage shall be accounted for by reservoir and stream routing techniques as appropriate. 8. When applicable, flood peak discharge estimates used in the critical flood analysis shall be checked for reasonableness by comparison with other flood peak data such as: actual flood peak discharges recorded for similar drainage basins, peak discharge estimates from other studies of similar basins, and estimates from alternative modeling techniques. Hydraulic Requirements Critical Flood Guidelines Page 8 Hydrologic analyses for the critical flood determination conducted in accordance with OAC Rule 1501:21-13-02 shall conform to the following standards: 1. Water-surface profiles shall be determined by step-backwater procedure whenever applicable together with other pertinent hydraulic formulae. Computer programs used for water surface profile analysis shall be step-backwater algorithms such as the United States Army Corps of Engineers s HEC-RAS program. 2. Dam failure discharges shall be determined by a flood routing program equipped with dam failure analysis routines and/or a specific dynamic reservoir routing program such as the Boss Dambreak program. 3. Initial water-surface elevation used in step-backwater analysis shall be based on normal depth or determined from stage-discharge rating at a control section. If normal depth is used to determine initial water-surface elevation, the modeling shall include at least three initial cross sections beyond the terminus of the stream reach where actual flood elevations are required to allow for iterative convergence of flood profile. 4. Models shall be calibrated using measured profiles and reliable high-water marks of past floods when such information is available. Models shall match known high-water marks within plus or minus 0.5 foot. 5. Any cases where computation of water-surface profiles may require use of two-dimensional computer modeling, dynamic wave routing or other special analysis shall be approved by the chief. 6. Location, alignment and subdivision of channel and floodplain cross-sections used in stream modeling shall be based on field observations and careful examination of topographic maps and aerial photographs. Cross-sections shall be typical of adjacent upstream and downstream reaches. A minimum of four cross-sections is required for the critical flood analysis. 7. Cross-sections shall be located where needed to account for changes in dimensions and roughness of the channel and floodplain. Cross-sections shall be located at all significant breaks in channel grade. Channel reach length between cross-sections shall be short enough to avoid excessive change in conveyance, velocity head, or energy loss. 8. Alignment of cross-sections shall normally be perpendicular to direction of flow in channels and overbank areas. For streams with severe meanders, where the majority of stream flow deviates from the channel, the alignment of cross-sections shall be perpendicular to the center of mass of the flow. 9. Floodplain and channel cross-sections shall be subdivided into at least channel and overbank Critical Flood Guidelines Page 9 areas for analysis. Additional subdivisions may be required depending on the specific crosssection. Ineffective flow areas shall be excluded from cross-sections as appropriate to insure accurate modeling of stream flow. 10. Modeling of existing channel constrictions shall include a sufficient number of upstream and downstream cross-sections to accurately model flow lines. 11. Modeling of bridges and culverts using routines in step-backwater computer programs shall require at least four cross sections. Sections shall be located at the upstream and downstream sides of the structures and at appropriate distances upstream and downstream of the structures to properly model transitions and ineffective flow areas. Additional cross-sections shall be used as needed to establish starting water elevation and evaluate upstream and downstream impacts. Options in step-backwater programs for direct input of bridge and culvert profiles based on hydraulic charts and other sources may be used when appropriate. 12. Modeling of developed floodplain areas with buildings shall normally be based on adjustment of roughness coefficients by procedures such as those developed by the United States Geological Survey. In cases where it involves a single building or a limited number of buildings, these structures may be modeled using at least four cross-sections to model the blocked portion of the floodplain, ineffective flow areas, and open areas upstream and downstream of the buildings. 13. Split flow analysis shall be considered when stream flows divide around an island or overflow the banks of the main stream and take a different flow path. The analysis shall address the reduction in flow in the downstream reach when overflows leave the main channel and enter another basin. Acceptance of the procedures used in the split flow analysis will be required by the chief on a case by case basis. 14. Modeling of tributary streams shall proceed from initial water-surface elevations determined from normal depth on the main stream unless coincident peak situation applies or tributary flow depth is higher than the corresponding main stream event. Flood Study Report 1. The critical flood analysis conducted in accordance with OAC Rule 1501:21-13-02 shall be summarized in a flood study report. Contents of the report shall include all applicable narratives and exhibit items detailed under this guideline. 2. Reports of the critical flood analysis shall contain a narrative text that is organized into thefollowing sections: Introduction, Area Studied, Hydrologic Analysis, Hydraulic Analysis, and Summary of Impact. Critical Flood Guidelines Page 10 A. The introductory section of critical flood reports shall state the purpose of the study, cite the authority for the work, summarize the scope of the work, and discuss study requirements. B. The area studied section of the critical flood report shall describe the location of the study area, flooding source, and define the critical routing reach for the dam. C. The hydrologic analysis section of the critical flood report shall discuss the following items: 1. Methodology and adequacy for current study of flood discharge estimates for the flooding source. 2. Methodology used to compute peak discharge estimates for flooding source and document sources of hydrologic data. 3. Include a summary of discharges in a table that gives the following information: name of flooding source, location point on stream, drainage area in square miles, and the various flood frequency peak discharges for the with and without dam failure conditions. 4. Review any historical flood information for the flooding source and discuss comparative flood peak estimates based on alternative methodology as appropriate. C. The hydraulic analysis section of the critical flood report shall discuss the following items: 1. Methodology used to generate flood profiles for the study reach. 2. Discuss methodology, engineering assumptions, and the hydraulic parameters for their adequacy in the development of the dam failure discharges. 3. Discuss methodology and field procedures used to generate flood profiles including: how cross sections were obtained, how channel and overbank reach lengths were determined, how roughness factors were estimated, how dimensions of hydraulic structures were obtained, how water surface elevations were computed, and how starting water elevations were determined. 4. Describe the concepts and procedures used to comply with the no impact requirements for critical flood determination. 5. Describe methods used to evaluate the hydraulic impact of a dam failure flood on Critical Flood Guidelines Page 11 the critical routing reach, and summarize results of the hydraulic analysis. 3. Reports of the critical flood analysis, conducted in accordance with OAC Rule 1501:21-13-02 may include, but not be limited to the following exhibits: work maps, flood profiles, and photographs. A. Work maps shall contain coverage of the critical routing reach and all potential affected structures. 1. Each work map shall be identified with the following information: date map was prepared, map bar scale, north arrow, source of base map and date, whether map is one of several maps, and a legend, if applicable, indicating any symbols used for identifcation purposes on the map. 2. Work maps shall show existing topographic contours, low-water outline of streams and lakes, cross sections, boundaries of floodplains associated with the critical flood discharges. B. Flood profiles shall be prepared for all flood recurrence interval events studied. C. Photographs may be used in the critical flood analysis report to supplement text material and provide documentation of observed field conditions at the time of the study. Photographs may include views of the critical routing reach and its overbank areas, hydraulic structures, any structures in the floodplain that are potentially affected by the dam failure discharges, and other significant features of the landscape. D. A certification page signed and stamped by the registered professional engineer in charge of the study. The engineer shall certify that the data for the physical parameters use in the critical flood study represent actual field conditions. E. Submittals to the chief of reports and technical documentation of critical flood studies conducted in accordance with OAC Rule 1501:21-13-02 shall be accompanied by a cover letter identifying the report, its purpose, and any action requested of the chief. Critical Flood Guidelines Page 12 DETERMINE CRITICAL ROUTING REACH (SEE DEFINITION) ESTABLISH CLASS OF DAM BASED ON D.O.W. CRITERIA FOR THE PURPOSE OF ESTABLISHING THE BASE INITIAL DESIGN FLOOD . INDICATE CRITERA (HEIGHT OF DAM, TOTAL STORAGE VOLUME, POTENTIAL DOWNSTREAM HAZARD) USED TO ESTABLISH THE CLASSIFICATION OF THE DAM. START INCREMENTAL DAMAGE ANALYSIS ROUTINE TO DETERMINE INLFOW DESIGN FLOOD (CRITICAL FLOOD) FOR DAM USING THE FOLLOWING PROCEDURE: PERFORM A FLOOD ROUTING ANALYSIS ON A BASE FLOOD FLOW (FLOOD A) OF A MAGNITUDE ESTABLISHED BY OHIO ADMINISTRATIVE RULE 1501:21-13-02 (B). THIS FLOOD SHALL BE ROUTED THROUGH THE CRITICAL ROUTING REACH (HEC-1, HEC-HMS) DOWNSTREAM OF THE DAM. PERFORM SECOND ANALYSIS FOR THE DAM FAILURE FLOOD (FLOOD B), WHICH IS THE RESULT OF THE PEAK DISCHARGES DETERMINED FROM A SIMULATED DAM FAILURE (HEC-1, DAMBREAK MODELS USED) COMBINED WITH THE INITIAL BASE FLOOD FLOW (FLOOD A). DECREASE INFLOW DESIGN FLOOD BY AN INCREMENTAL AMOUNT USING A PERCENTAGE REDUCTION TECHNIQUE. THE ADJUSTED FLOW NOW BECOMES THE NEW BASE FLOOD FLOW (FLOOD A). PERFORM A BACKWATER ANALYSIS (HEC-RAS) FOR THE CRITICAL ROUTING REACH FOR THE ROUTED BASE FLOOD FLOW (FLOOD A) PERFORM A BACKWATER ANALYSIS (HEC-RAS) FOR THE CRITICAL ROUTING REACH FOR THE COMBINED BASE FLOOD AND DAMBREAK FLOWS (FLOOD B) 2 1 IS THE ADJUSTED BASE FLOOD FLOW (FLOOD A) GREATER THAN THE MINIMUM ALLOWABLE INFLOW DESIGN FLOOD FOR THE DAM? YES 3 NO Critical Flood- The flood that would result in no additional loss of life, health or property along a critical routing reach downstream of the dam for overtopping failure of the dam when compared to damages caused by the flood in the absence of a dam overtopping failure. The design for the critical flood must be for specific site conditions and based on a quantitative and relative impact analysis of the downstream critical routing reach. The critical flood is determined by a simulated dam failure analysis after predicting the limits of the critical routing reach associated to the dam, and taking into account the physiographic, hydrologic, and hydraulic characteristics of the drainage area for both the dam and the critical routing reach. Critical Routing Reach- The entire floodplain beginning from the dam to a specific location downstream of the dam where life, health or property is potentially affected by failure of the dam. IS A POTENTIALLY AFFECTED STRUCTURE LOCATED WITHIN THE CRITICAL ROUTING REACH? YES NO 5 EVALUATE POTENTIAL DAMAGE IN CRITICAL ROUTING REACH CAUSED BY FLOOD A. EVALUATE POTENTIAL DAMAGE IN CRITICAL ROUTING REACH CAUSED BY FLOOD B. RECORD PREVIOUS INFLOW DESIGN FLOOD USED IN INCREMENTAL ANALYSIS (OUTPUT 1) PROCESS FOR DETERMINING THE CRITICAL FLOOD FOR DAMS Critical Flood Guidelines Page 13 DOES THE DAM FAILURE FLOOD CAUSE ANY EXPECTED ADDITIONAL (i.e., ABOVE WHAT HAS ALREADY BEEN PREDICTED BY THE BASE FLOOD WITHOUT A DAM FAILURE) LOSS OF LIFE, HEALTH, AND PROPERTY? IS THE MAXIMUM INCREMENTAL INCREASE IN DEPTH GREATER THAN 2.0 FT? CALCUATE THE MAXIMUM INCREMENTAL INCREASE IN DEPTH THROUGH THE CRITICAL ROUTING REACH AT POINTS OF INTEREST. CALCULATE THE AVERAGE FLOODPLAIN FLOW VELOCITY THROUGH THE CRITICAL ROUTING REACH AT CRITICAL POINTS OF INTEREST. IS THE PRODUCT OF THE AVERAGE FLOODPLAIN FLOW VELOCITY (FT/SEC) FOR FLOOD B AND ITS CORRESPONDING INCREMENTAL INCREASE IN DEPTH OF FLOOD (FT.) GREATER THAN 7.0? 2 3 3 3 1 YES, IMPACT YES, IMPACT NO (NO ADDITIONAL IMPACT) DIFFERENCE IN FLOOD ELEVATIONS OBTAINED FROM BACKWATER ANALYSIS WHICH IS THE FLOOD B PROFILE MINUS THE FLOOD A PROFILE ALONG THE CRITICAL ROUTING REACH. A MEAN VELOCITY DISTRIBUTION, CALCUALTED FROM THE BACKWATER ANALYSIS, IS REQUIRED FOR ALL CROSS SECTIONS ALONG THE CRITICAL ROUTING REACH. YES, IMPACT NO, (NO ADDITIONAL IMPACT) NO, (NO ADDITIONAL IMPACT) Critical Flood Guidelines Page 14 A DOCUMENTATION OF THE INCREMENTAL DAMAGE ANALYIS SHALL INCLUDE BUT NOT BE LIMITED TO THE FOLLOWING: CRITICAL FLOOD PLOTTED ON TOPOGRAPIC MAPS OF THE AFFECTED AREAS 3 A HYDRAULICALY APPROPRIATE CROSS-SECTIONS OF THE DOWNSTREAM CHANNEL SHOWING FLOOD STAGES WITH VELOCITIES AND DISCHARGES FOR THE INFLOW DESIGN FLOOD AND THE INFLOW DESIGN FLOOD PLUS DAMBREAK FLOWS INCREMENTAL DAMAGE AND LOSS OF LIFE DETERMINATIONS SUMMARY OF ALL HYDROLOGIC AND HYDRAULIC PARAMETERS USED IN THE ANALYSIS BACKWATER PROFILES FOR THE VARIOUS FLOOD STAGES FOR THE CRITICAL ROUTING REACH AERIAL PHOTOGRAPHS OF THE AFFECTED AREAS IF NECESSARY DIGITAL COPIES OF THE COMPUTER MODELS WITH PRINTOUTS FOR THE BACKWATER ANALYSIS AND THE FLOOD ROUTINGS STOP BASE FLOOD FLOW IS EQUAL TO THE INFLOW DESIGN FLOOD AND THE CRTITICAL FLOOD FOR THE DAM IS EQUAL TO THE PREVIOUS PASSING INCREMENTAL FLOOD (RECALL OUTPUT 1). 5 USE MINIMUM CRITICAL FLOOD ESTABLISHED BY OAC RULE 1501:21-13-02 (B) AS THE DESIGN PREPARE FLOOD STUDY REPORT FLOOD FOR THE DAM. PREPARE FLOOD STUDY REPORT DID THE ANALYSIS RESULT IN ANY POTENTIAL D/S IMPACTS AS A RESULT OF A DAM FAILURE? YES IF CLASSIFICATION OF DAM IS BASED SOLEY ON D/S HAZARD, RE-EVALUATE CLASSIFICATION OF DAM. NO DIVISION OF WATER OHIO DEPARTMENT OF NATURAL RESOURCES Ohio Department of Natural Resources Division of Water Fact Sheet Fact Sheet 99–60 Dam Safety: Critical Flood Design Criteria Continued on back! hazard, drainage area, and downstream topography are such that traditional flood design standards do not accurately account for the downstream hazard, critical flood criteria allow for a reduction of up to 60% of the design flood. For example, let’s look at a Class I dam. This type of dam is required to safely pass the 100% PMF through its spillway system without endangering the safety of the dam. As rain falls onto a dam’s watershed, some of the rainfall will infiltrate into the ground, some will evaporate, and most of it will runoff across the ground into the pond or lake. The water level in the impoundment will begin to rise while simultaneously flowing through the dam’s spillway(s). As water exits the dam’s spillway(s), the downstream channel will begin to fill and flow accordingly. For most dams, the downstream channel will likely fill with some water, but most of the water flows downstream without backing up significantly. For those few cases where the downstream channel fills rapidly to the point where water rises dramatically and failure of the dam would have no additional significant increase in elevations of floods downstream, the design flood can be reduced. In other words, there may be a point, say 50% of the PMF (the critical flood in this case), where designing for additional flood capacity for the dam is no longer reasonable. If the dam were to fail, the downstream hazard would not be further adversely effected. In this case, the spillway system may be designed for half of what it would have been originally designed, therefore saving dollars without increasing the hazard to the downstream area. What is the Maximum Reduction in Design Flood? The design flood can be reduced approximately up to 60% for each class of dam: Class I 100% PMF down to no less than 40% PMF Class II 50% PMF down to no less than 20% PMF Class III 25% PMF down to no less than 100 Year Ohio’s Dam Safety Rules require dams to pass floods through their spillways without endangering the safety of the dam. The magnitude of the design flood is directly related to the classification of the dam - which in turn is related to the dam’s downstream hazard and/or the dam’s height. The greater the downstream hazard, i.e., loss of human life, high-value property, etc., the larger the design flood. Definitions The probable Maximum Precipitation (PMP) is the greatest depth (amount) of precipitation for a given storm duration, that is theoretically possible for a particular area and geographic location. The Probable Maximum Flood (PMF) is the flood that may be expected from the most severe combination of critical meteorological and hydrologic conditions that are reasonably possible in a particular drainage area. Classification of Ohio Dams Dams in Ohio are divided into four classes based on the storage volume of the impoundment, dam height, and potential downstream hazard (how far downstream residences, businesses are, etc.). More details about the classification system can be found in the Dam Safety: Classification of Structures Fact Sheet No. 94-29. Critical Flood Design Criteria Specific guidelines are available for preparing a critical flood engineering analysis. This analysis must be performed by a professional engineer licensed in the State of Ohio. The guidelines can be downloaded from the Division of Water’s world wide web site, (http://www. dnr.state.oh.us/odnr/water/temp/dartrlsa.html), or you can request a copy by calling our office directly. Could the Critical Flood Analysis Make a Difference for My Dam? The critical flood criteria were developed to make Ohio’s Dam Safety Rules more flexible in recognizing that some dams fall outside of the typical parameters used in designing spillway capacity. Specifically, for those circumstances where the size of the dam, its downstream Ted Strickland Governor • Sean D. Logan Director • Deborah Hoffman Chief What Factors Should I Consider Before Proceeding With an Analysis? The cost of the analysis can be thousands of dollars. Let’s assume that a dam inspection by our engineers reveals that a dam is deficient in its ability to pass the design flood. It would be beneficial to have an analysis performed if the design flood was reduced enough so that the spillway system did not need to be upgraded or replaced. Let’s assume that upgrading the spillway system costs $50,000. If the cost of the critical flood analysis was $5,000, the cost of the critical flood analysis would be warranted. Sometimes it can be straightforward to predict whether or not an analysis would be beneficial. However, in those cases where it may not be clear, other options should be considered. For example, if room exists in one of the dam’s abutments to excavate an emergency spillway or perhaps enlarge an existing emergency spillway, it may be more cost effective to do so. There is always a risk in running an analysis and finding out that the reduction in design flood is insignificant and the spillway system enlargement is still required. A critical flood analysis approved by our office means that a reduced design flood is acceptable for your dam. Please note that a reduction in the design flood for your dam may increase the risk of failure or damage to your dam. This could result in an economical burden on the dam owner. This risk should be closely considered! How Can I Apply for the Critical Flood Reduction? A request for consideration must be submitted to the Chief of the Division of Water. The request must be accompanied by supporting calculations based upon an analysis performed by a professional engineer registered in the State of Ohio. The engineer’s analysis must conform to the critical flood guidelines provided by the Division of Water. Before applying, it is best to call and speak with an engineer in the Division’s Dam Safety Engineering Program. What Restrictions Are There? A critical flood reduction based upon planned evacuation, probability of inhabitation, or monetary recovery of property damage will not be considered. In other words, guaranteeing that a downstream residence or business will be evacuated during a dam failure will not be considered. In situations where the downstream hazard may or may not be inhabited, such as in the case of a campground, rental property, hotel, and so forth, the probability of inhabitation will not be considered. Also, understanding that failure of a dam will damage downstream property and guaranteeing that the damages will be paid for will also not be considered. Finally, if the downstream hazard were to change, the critical flood exemption could be nullified. Any other questions, comments concerns, or fact sheet requests, should be directed to the Division of Water at the following address: I 11/04/99 Ohio Department of Natural Resources Division of Water Dam Safety Engineering Program 2045 Morse Road Columbus, Ohio 43229-6693 Voice: (614) 265-6731 Fax: (614) 447-9503 Website: http://www.dnr.state.oh.us/water UNOFFICIAL 785:25 Page 1 of 20 UNOFFICIAL TITLE 785. OKLAHOMA WATER RESOURCES BOARD CHAPTER 25. DAMS AND RESERVOIRS Introduction: This document contains permanent amendments to Chapter 25 adopted by the Oklahoma Water Resources Board that became effective May 27, 2010. Also, this document was prepared by Oklahoma Water Resources Board staff as a convenience to the reader, and is not a copy of the official Title 785 of the Oklahoma Administrative Code. The rules in the official Oklahoma Administrative Code control if there are any discrepancies between the Code and this document. Subchapter Section 1. General Provisions ........................................................................................... 785:25-1-1 3. Responsibility, Classification and Design Standards......................................... 785:25-3-1 5. Applications and Approval of Construction ....................................................... 785:25-5-1 7. Post Approval Actions ...................................................................................... 785:25-7-1 9. Actions After Construction ................................................................................ 785:25-9-1 11. Administrative Penalties and Procedures ....................................................... 785:25-11-1 [Authority: 82 O.S., Sections 105.25 – 105.27 and 1085.2] [Source: Codified 12-31-91] SUBCHAPTER 1. GENERAL PROVISIONS Section 785:25-1-1. Purpose 785:25-1-2. Definitions 785:25-1-3. Violations and penalties 785:25-1-4. Variances and waivers 785:25-1-1. Purpose The rules of this Chapter on reservoir requirements and safety of dams set forth minimum standards for construction and maintenance of dams based on size and hazard classification, application requirements for approval of plans and specifications, and inspection requirements. These rules are adopted pursuant to 82 O.S. 1981, §§105.27, 110.1 et seq. (Oklahoma Dam Safety Act) and 1085.2(7), and Public Law 92-367, 92nd Congress, H.R. 15951, approved August 8, 1972 (33 U.S.C. 467 et seq.). Under no circumstances shall the rules in this Chapter be construed to deprive or limit the Oklahoma Water Resources Board of any exercise of powers, duties, and jurisdiction conferred by law nor to limit or restrict the amount or character of data or information which may be required from any owner of any dam for the proper administration of the law. [Source: Amended at 10 Ok Reg 3287, eff 6-25-93] 785:25-1-2. Definitions The following words and terms, when used in this Chapter, shall have the following meaning, unless the context clearly indicates otherwise: "Alteration" means only such alteration as may affect the safety of a dam or reservoir. "Application" means a formal request to the Board and the first step required by law to acquire the right to perform or engage in activities regulated by the Board. "Board" means and refers to the Oklahoma Water Resources Board or any employee or agent or staff member thereof. UNOFFICIAL 785:25 Page 2 of 20 "Breach analysis" means an engineering analysis to determine the area that would be inundated by the failure of a dam. "Dam" means any artificial barrier, together with appurtenant works, which does or may impound or divert water. "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 or reservoir. "Failure" with respect to a dam means any uncontrolled release of water. "Gully plug" means any grade stabilization structure that has less than five acre-feet of water storage available below the principal spillway elevation and less than 50 acre-feet of storage volume below the emergency spillway elevation. "Interested party" means party. "Loss of human life" means the human fatalities that would result from a failure of the dam, excluding the occasional passer-by or recreationist and without considering evacuation or other emergency actions. "Notice by publication" means unless otherwise specifically provided, publication in a daily or weekly newspaper of general circulation once a week or two (2) consecutive weeks (minimum seven day interval). "Owner" means any person who, jointly or severally, owns, controls, maintains, manages, or proposes to construct a dam or reservoir, and includes those shown by records of the county registrar of deeds to have some interest, fee, easement, or otherwise, in the land on which the dam and lake lie and may also include those persons who may derive a direct pecuniary benefit from the existence of the lake [82:110.3]. "Party" means a person or agency named and participating, or properly seeking and entitled by law to participate, in hearings other than hearings on Board rules, regulations and standards. "Person" means any individual, firm, partnership, association, corporation, any trust formed for the benefit of an individual, business or any public entity, federal agency, state agency, the State or any political subdivision thereof, municipalities, and any other legal entity [82:110.3]. "Repairs" means only such repairs as may affect the safety of a dam or reservoir. "Reservoir" means any surface depression which contains or will contain the water impounded by a dam. "Statistical twenty-four (24) hour, fifty (50) year storm" means a storm of twenty-four (24) hour duration with a probable recurrence interval of once in fifty (50) years as defined by the National Weather Service in Technical Paper Number 40, "Rainfall Frequency Atlas of the United States," May 1961, and subsequent amendments, or equivalent regional or state rainfall probability information developed therefrom. "Water storage elevation" means that elevation of water surface which may be obtained by the temporary or permanent storage of water. This elevation is normally the lowest point on the top of the dam. [Source: Amended at 10 Ok Reg 3287, eff 6-25-93; Amended at 11 Ok Reg 2931, eff 6-13-94] 785:25-1-3. Violations and penalties (a) Under Section 105.20 of Title 82 of the Oklahoma Statutes, the continued use of works which are unsafe, after receiving notice to repair, and the refusal to change unsafe works when directed to do so, or the injury or obstruction of waterworks shall be a misdemeanor and each day such violation continues shall be a separate violation. (b) Under the Oklahoma Dam Safety Act (82 O.S. Supp. 1992, §§110.1 et seq.), the Board is authorized to issue emergency orders without prior notice and hearing and orders after notice and hearing requiring an owner to take action as necessary to put a dam in safe condition. In addition, the Board may impose administrative penalties against owners of dams who fail, UNOFFICIAL 785:25 Page 3 of 20 refuse or neglect to comply with the provisions of the Oklahoma Dam Safety Act. Procedures for imposition of such penalties are found in Subchapter 11 of this Chapter. [Source: Amended at 10 Ok Reg 3287, eff 6-25-93] 785:25-1-4. Variances and waivers Applicants who request a variance or waiver to rules specified in this chapter must demonstrate, and shall bear the burden of demonstrating that operations under the variance will equal or exceed the protections accorded by the particular rule for which the variance is sought. The variance may also be granted if the Board finds that the cost of compliance with the rule without a variance would impose significant expense without providing for additional safety of the construction for which the variance or waiver is sought, and integrity of the dam will not be adversely affected. The Board may require that a registered professional engineer certify that the variance or waiver being requested will not adversely affect the integrity of the dam. [Source: Added at 21 Ok Reg 2625, eff 7-1-2004] SUBCHAPTER 3. RESPONSIBILITY, CLASSIFICATION AND DESIGN STANDARDS Section 785:25-3-1. Dams subject to Board's jurisdiction 785:25-3-2. Owner's responsibility 785:25-3-3. Classification of size and hazard potential 785:25-3-4. Dams considered unsafe and menace to life and property 785:25-3-5. Minimum design standards (other than spillway) 785:25-3-6. Minimum spillway performance standards 785:25-3-7. Minimum outlet conduit capacities 785:25-3-8. Measuring devices 785:25-3-9. Prohibited construction 785:25-3-10. Prohibited vegetation 785:35-3-11. Minimum safety factors 785:25-3-1. Dams subject to Board's jurisdiction (a) Dams, together with appurtenant works, which meet the following alternative criterion are subject to the provisions of [82:110.4] the Oklahoma Dam Safety Act and this Chapter of the Board's rules: (1) Dams which are or will be twenty-five (25) feet or more in height from the natural bed of the stream or watercourse at the downstream toe of the barrier or from the lowest elevation of the outside limit of the barrier or from the lowest elevation of the outside limit of the barrier if it is not across a stream channel or watercourse, to the top of the dam [82:110.4]; or (2) Dams which have or will have an impounding capacity of fifty (50) acre-feet or more [82:110.4]; provided, however, any barrier to the flow of water which does or may impound water and which is or will be not in excess of six (6) feet in height, regardless of storage capacity, or which has or will have a storage capacity not in excess of fifteen (15) acre-feet, regardless of height, shall not be subject to regulation . . . unless it is determined to have a high hazard potential classification under these rules [82:110.4] or except as hereinafter provided. The figure in Appendix A of this Chapter presents a graphic illustration of the height and storage criteria reviewed to determine the Board's authority relating to dams. (b) No barrier to the flow of water determined by the Board to be designated primarily for roadfill shall be subject to regulation under this [82:110.4] Chapter. (c) Gully plugs are not subject to regulation under this [82:110.4] chapter of the Board's rules. UNOFFICIAL 785:25 Page 4 of 20 (d) Dams constructed by any agency of the United States Government shall not be subject to regulation under this Chapter during or after construction while such dams remain under the supervision of any officer or agency of the United States [82:110.4] [Source: Amended at 10 Ok Reg 3287, eff 6-25-93; Amended at 11 Ok Reg 2931, eff 6-13-94] 785:25-3-2. Owner's responsibility (a) General. (1) Owners of dams to which the provisions of this Chapter apply shall have the responsibility to provide for the safety of such works by making any necessary changes to put the works in a safe condition. (2) Such responsibility includes but is not necessarily limited to the following: the filing of an application to construct, enlarge, alter or repair the dam pursuant to Subchapter 5, the modification of the dam to meet applicable minimum requirements in this Subchapter, and the adequate maintenance, operation, and inspection of an existing dam. (b) Multiple owners. (1) When there is more than one owner of a dam, the Board shall consider all such owners responsible for the safety of such dam unless evidence to the contrary shows otherwise. (2) The Board shall provide copies of inspection reports to at least one owner of record at the Board and shall provide notice of hearing on dam safety related matters to such owner with an instruction that the notice shall be delivered or mailed to all owners. (3) Unless otherwise agreed by all the owners and the Board, the Board may, after such notice and hearing, order all the owners to take whatever remedial action is necessary to put the dam in a safe condition. (4) The Board will not attempt to delineate levels of responsibility or allocate particular items of action among the owners. (c) Transfer of ownership. Upon transfer of ownership of the works, the new owner shall notify the Board of such transfer. [Source: Amended at 9 Ok Reg 1675, eff 5-11-92; Amended at 14 Ok Reg 2766, eff 7-1-97] 785:25-3-3. Classification of size and hazard potential (a) All dams shall be classified as to size and for potential hazards as follows: (1) Size Classification of Dams. The size classification shall be based on the following chart: (A) Small: (i) Storage – less than10,000 Ac-Ft. (ii) Height – less than 50 Ft. (B) Intermediate: (i) Storage – between 10,000 and 50,000 Ac-Ft. (ii) Height – between 50 and 100 Ft. (C) Large: (i) Storage – over 50,000 Ac-Ft. (ii) Height – over 100 Ft. (2) Hazard-Potential Classification of Dams. The hazard-potential classification of a dam is determined by the downstream risk in the event of a failure, without regard to the physical condition of the dam, as follows: (A) Low. Dams assigned the low hazard-potential classification are those where failure would result in no probable loss of human life and low economic losses. (B) Significant. Dams assigned the significant hazard-potential classification are those dams where failure would result in no probable loss of human life but can cause economic loss or disruption of lifeline facilities. UNOFFICIAL 785:25 Page 5 of 20 (C) High. Dams assigned the high hazard-potential classification are those where failure will probably cause loss of human life. (b) Hazard classification subject to regulation and change. (1) For dams which were inventoried in the National Safety of Dams program authorized under 33 U.S.C. 467 et seq., and for which "Phase I" reports pursuant to said inventory were prepared, the hazard classifications set forth in such "Phase I" reports shall be presumed accurate. If the owner of the dam disagrees with the hazard classification, the owner shall have the burden to show that such hazard classification is inaccurate and should be changed. (2) At the discretion of the Board, any proposed or existing dam considered to have classification of a high hazard potential may be subject to regulation regardless of size or impounding capacity. (3) The hazard potential classification may change as the area downstream from a dam develops and the dam may be reclassified from time to time under the provisions of 785:25-9-10 and 785:25-9-11. [Source: Amended at 11 Ok Reg 2931, eff 6-13-94] 785:25-3-4. Dams considered unsafe and menace to life and property (a) In determining whether a dam is unsafe and a menace to life and property [82:105.27] under the provisions of Section 105.27 of Title 82 of the Oklahoma Statutes and the corrective actions necessary to put a dam in a safe condition, the Board shall review the requirements set forth in rules of this Chapter, and recommendations on matters which directly affect the integrity of dams set forth in DESIGN OF SMALL DAMS (1977) and DESIGN OF GRAVITY DAMS (1976), published by the U.S. Department Interior Bureau of Reclamation (BOR), ENGINEERING AND DESIGN MANUALS, SERIES EM-1110, published by the U.S. Department of the Army, Corp of Engineers (COE), the ENGINEERING FIELD MANUAL and TECHNICAL RELEASE NO. 60, published by the U.S. Department of Agriculture, Natural Resources Conservation Service, or equivalent recommendations. (b) Existing dams which are in imminent peril of failure shall be considered unsafe and a menace to life and property [82:105.27] under the provisions of Section 105.27 of Title 82 of the Oklahoma Statutes. [Source: Amended at 9 Ok Reg 1676, eff 5-11-92; Amended at 10 Ok Reg 3287, eff 6-25-93; Amended at 14 Ok Reg 2766, eff 7-1-97] 785:25-3-5. Minimum design standards (other than spillway) (a) The construction of the downstream embankment slope shall not be steeper than 3 horizontal units to each 1 vertical unit (3:1) to provide adequate factors of safety against sliding, sloughing or rotation in the embankment and foundation, unless a stability analysis is performed which shows a steeper slope provides an adequate factor of safety. (b) Except as otherwise provided in this Chapter, all dams must be designed by methods, procedures and criteria that meet or exceed acceptable dam safety engineering practices, including those found in the federal agency publications referenced in 785:25-3-4. 785:25-3-6. Minimum spillways performance standards (a) General performance standards (1) Except as otherwise provided in this Chapter, all dams must meet or exceed the following performance standards as determined by analysis of plans and specifications for the dam and existing site conditions. UNOFFICIAL 785:25 Page 6 of 20 (2) Owners of existing dams which do not meet the following performance standards must make necessary changes in the dam to meet the applicable performance standards. (3) The discharge capacity and/or storage capacity of the project shall be capable of passing the indicated spillway design flood without infringing on the minimum freeboard requirements, provided that a design which includes overtopping of the dam may be authorized if specifically approved by the Board. (4) The minimum performance standards expressed as magnitude of spillway design flood and minimum freeboard will be assigned to the various size and hazard potential classification determined under 785:25-3-3 as follows: (b) Minimum Performance Standards MINIMUM SPILLWAY SIZE HAZAR D DESIG N FLOOD MINIMU M FREEBO ARD Small Low 25% PMF 0 Feet Small Significa nt 40% PMF 0 Feet Small High 50% PMF 1 Foot Intermedia te Low 25% PMF 1 Foot Intermedia te Significa nt 50% PMF 1 Foot Intermedia te High 75% PMF 3 Feet Large Low 50% PMF 1 Foot Large Significa nt 75% PMF 1 Foot Large High 100% PMF 3 Feet (c) Amending minimum freeboard. The minimum freeboard requirements may be amended by the Board on a case-by-case basis for good cause shown by the owner. (d) Probable maximum flood. (1) PMF means and refers to the Probable Maximum Flood and is defined as the flood that may be expected from the most severe combination of critical meterorologic and hydrologic conditions that are reasonably possible in the region as listed in Hydrometeorological Report No. 51, National Weather Service. (2) Since design floods are usually determined by using mathematical computations through computer modeling and since several different acceptable models are available, flood design calculations must fall within plus/minus 5% PMF of the Board's current model results. (3) The PMF storm should be of appropriate duration to adequately reflect the size and hydrologic characteristics of the watershed in which the dam is located. UNOFFICIAL 785:25 Page 7 of 20 (e) PMF on dam designated for regulation. A dam which the Board has determined is subject to regulation because of its high hazard potential, although otherwise considered too small, shall be required to safely pass 25% PMF with no minimum freeboard. (f) Dams constructed prior to June 13, 1973. Any dam constructed prior to June 13, 1973 and which is classified as intermediate size and high hazard potential according to 785:25-3-3 shall be required to pass a minimum design of 50% of the PMF. Any dam constructed prior to June 13, 1973 and which is classified as large size and high hazard potential according to 785:25-3-3 shall be required to pass a minimum design flood of 75% of the PMF. [Source: Amended at 9 Ok Reg 1676, eff 5-11-92; Amended at 12 Ok Reg 2687, eff 7-1-95] 785:25-3-7. Minimum outlet conduit capacities (a) Requirements for outlet conduit capacity shall be as follows: (1) All dams subject to the Board's jurisdiction shall have at least one outlet conduit of sufficient capacity to prevent interference with natural streamflow and injury of downstream appropriators and domestic users. Absent evidence to the contrary, the minimum size of the outlet conduits shall be as set forth in subsection (d) of this section. (2) The height of the outlet conduit shall be no more than five feet (5') above the natural stream channel unless otherwise ordered by the Board. The capacity of the reservoir below the outlet conduit shall be designated as the inactive pool. (b) Conduit operation. All conduits shall be gate- or valve-operated on the upstream side and shall be maintained in an operable condition at all times. (c) Conduit design life. The design life expectancy of the conduit shall be equal to or greater than the design life of the dam. (d) Minimum size outlet conduit requirements. The outlet conduit must be of sufficient size to draw down the entire reservoir to the inactive pool within twenty (20) days, provided that minimum size outlet requirements are as follows: (1) For less than 100 acre-feet normal pool capacity (at principal spillway), the minimum size of conduit is 6-inch pipe. (2) For 101 to 150 acre-feet normal pool capacity (at principal spillway), the minimum size of outlet conduit is 8-inch pipe. (3) For 151 to 200 acre-feet normal pool capacity (at principal spillway), the minimum size of outlet conduit is 10-inch pipe. (4) For 201-250 acre-feet normal pool capacity (at principal spillway), the minimum size of outlet conduit is 12-inch pipe. (5) For 251-300 acre-feet normal pool capacity (at principal spillway), the minimum size of outlet conduit is 14-inch pipe. (6) For 301-350 acre-feet normal pool capacity (at principal spillway), the minimum size of outlet conduit is 15-inch pipe. (7) For 351-500 acre-feet normal pool capacity (at principal spillway), the minimum size of outlet conduit is 16-inch pipe. (8) For more than 500 acre-feet normal pool capacity (at principal spillway), the minimum size of outlet conduit is 24-inch pipe. (e) Amendments of minimum requirements for good cause. Minimum size requirements may be amended by the Board for good cause. However, conduit must be of sufficient size to draw down the entire reservoir to the inactive pool within a period of not more than twenty (20) days. [Source: Amended at 21 Ok Reg 2625, eff 7-1-2004] 785:25-3-8. Measuring devices When required by the Board, measuring devices capable of providing an accurate water measurement must be provided to measure the flow of the stream above and below the UNOFFICIAL 785:25 Page 8 of 20 reservoir. Permanent staff gages may be required to be placed near the outlet of the reservoir and such other locations as specified by the Board and such gages shall be plainly marked in feet and tenths of feet. 785:25-3-9. Prohibited construction No construction or excavation other than that necessary for the operation, maintenance, investigation and monitoring of the dam and reservoir, shall be allowed on a dam or spillway structure or within fifty (50) feet from the line where such dam or spillway structure meets the natural grade unless otherwise ordered by the Board after a showing by substantial, competent evidence that the proposed construction will not affect the integrity of the dam or spillway structure. [Source: Amended at 9 Ok Reg 1676, eff 5-11-92] 785:25-3-10. Prohibited vegetation and erosion Trees and heavy vegetation shall be removed from the slopes and crest of earthen embankments and emergency spillway area. Trees and heavy vegetation shall also be removed from an area a minimum distance from the toe of the embankment of 30 feet. Dams shall be maintained such that internal or external erosion is prevented. If erosion is present it shall be repaired utilizing appropriate engineering practices. 785:25-3-11. Minimum safety factors As a guide for use by the Board and by engineers designing new dams, assessing the condition of existing dams or proposing modifications to existing dams, the following safety factors shall be utilized for: (1) Embankment dams: LOADING CONDITION MINIMUM FACTOR OF SAFETY* Steady seepage at emergency spillway crest 1.5 Rapid drawdown from principal spillway 1.2 Earthquake – reservoir at emergency spillway crest for downstream slope, reservoir at principal spillway for upstream slope 1.0 *The minimum factor of safety is calculated by the ratio of available shear strength stress required for stable equilibrium (2) Concrete dams or concrete portions thereof. LOADING MINIMUM UNOFFICIAL 785:25 Page 9 of 20 CONDITION FACTOR OF SAFETY ** (by hazard classification of dam) Principal spillway High and Significant Low level 2.25 2.0 Inflow design flood at maximum pool level 1.75 1.25 Principal spillway level with earthquake greater than 1.0 greater than 1.0 ** These minimum factors of safety apply to the calculations of stress and the shear friction factor of safety within the structure of the rock/concrete interface and foundation [Source: Amended at 11 Ok Reg 2931, eff 6-13-94] SUBCHAPTER 5. APPLICATIONS AND APPROVAL OF CONSTRUCTION Section 785:25-5-1. Application and fee required 785:25-5-2. Plans to be prepared by registered professional engineer 785:25-5-3. Content of plans and specifications 785:25-5-4. Additional report information 785:25-5-5. Notice of hearing 785:25-5-6. Affidavit of notice publication 785:25-5-7. Protest 785:25-5-8. Approval or denial of application 785:25-5-1. Application and fee required (a) General. (1) Any person who shall desire to construct, enlarge, alter, remove or repair any dam under the Board's jurisdiction shall submit an application upon printed forms which will be furnished by the Board upon request. (2) For the purposes of this subchapter, repair shall not be deemed to include routine normal maintenance. (3) The maps, plans, drawings, and specifications of the proposed work along with the required fee shall form a part of the application. (4) The application and attachments shall be filed in duplicate. (5) Notwithstanding the provisions of paragraph (1) of this subsection, an owner who proposes to construct a new dam classified as having a low hazard potential that will be used primarily for agriculture purposes, and will be designed or constructed with the assistance of a local conservation district or federal agriculture related agency, shall be required only to notify the Board of such construction and file a notice of completion in accordance with 785:25-7-6 [82:110.5]. UNOFFICIAL 785:25 Page 10 of 20 (b) Signature of applicant. The application shall be signed as follows: (1) If the applicant is an individual, the application shall be signed by the applicant or his duly appointed agent, who shall present satisfactory evidence of his authority to represent the applicant. (2) A joint application shall be signed by each applicant or his duly authorized agent, provided that a joint application by husband and wife may be signed by either party (joint applicants are required to select one among them to act for and represent the others in dealing with the Board). (3) If the application is by a partnership, the applicant shall be designated by the firm name followed by the words "A Partnership" and the application shall be signed by each of the general partners or, if signed by one partner or other agent, a written statement of the agent's authorization to make the application, signed by the other parties of interest, shall be attached to the application. (4) In the case of an estate or guardianship, the application shall be signed by the duly appointed guardian or representative of the estate, and a certified copy of the letter issued by the court shall be attached to the application. (5) In the case of a water district, county, municipality, etc., the application shall be signed by a duly authorized official, and a certified copy of the resolution or other authorization to make the application shall be attached. (6) In the case of a private corporation, the application shall be signed by a duly authorized person and, if not attested by the secretary or assistant secretary, a copy of the authorization shall be attached to the application. (c) Notary public required. All applicants shall subscribe and swear to the application before a Notary Public, who shall also sign his name and affix his seal to the application. (d) Water rights. Water rights requested or required in connection with a planned dam or reservoir may be approved based on preliminary information, however, no construction, enlargement, alternation or repair shall proceed until the application required by this Section has been submitted and approved in accordance with the rules of this subchapter and until the water rights required are approved. [Source: Amended at 10 Ok Reg 3287, eff 6-25-93; Amended at 14 Ok Reg 2766, eff 7-1-97] 785:25-5-2. Plans to be prepared by registered professional engineer Plans and specifications shall be prepared by a Registered Professional Engineer (59 O.S. 1981, §§475.1 and 475.15) who shall have training and/or experience concerning the analysis, design, and/or construction of dams and reservoirs, or by an engineer of any United States governmental agency acting in his official capacity (82 O.S. 1981, §105.27). However, if it is found that a project does not concern or involve the public welfare or the safeguarding of life, health or property, this requirement may be waived by the Board. 785:25-5-3. Content of plans and specifications (a) The plans and specifications shall, as a minimum, include the following: (1) A topographic map of the dam site showing the location of spillway and outlet works. The map shall also show all contiguous property and the owners thereof. The topographic maps for low hazard dams are not required to show test borings, test pits and borrow pits. (2) A profile along the dam axis showing the location, elevation, depth of borings or test pits including logs or bore holes and/or test pits, provided that plans and specifications for low hazard dams are not required to contain such a profile. (3) A maximum cross-section of the dam showing elevation and width of crest, slopes of upstream and downstream faces, thickness of riprap, zoning of earth embankment, location of cutoff and bonding trenches, elevations, size and type of outlet conduit, valves and operating mechanism. UNOFFICIAL 785:25 Page 11 of 20 (4) Area and capacity curves of the proposed reservoir. (5) Detailed drawings showing plans, cross and longitudinal sections of the outlet conduits, valves and controls for operating the same, and trash racks. (6) The discharge capacity in cubic feet per second of the spillway for each foot in water depth above the spillway crest up to the maximum high water level and the formula used in making such determinations. (7) Detailed plans of spillway structures, cross-section of the channel leading to and from the spillway, spillway profile, and procedures for operation of the spillway structure. (8) For high hazard potential classified dams, a breach analysis, and a map showing the breach inundation area utilizing guidelines provide by the Board. (9) A requirement, during the period of construction, for supervision by an engineer as required in 785:25-7-2. (10) A provision that the plans and specifications may not be substantially changed or changed in any material respect without prior written consent of the Board. (11) A provision stating in detail all matters necessary to ensure that construction is accomplished in a responsible manner and that needed control is exercised by an engineer as required in 785:25-7-2 to ensure construction of a safe structure. (b) The size of all plans and maps filed shall not be more than 11" x 17" and shall be drawn with an adequate number of views, in proper dimensions, and to a sufficiently large scale so that the plans and maps may be readily interpreted and studied. In addition to the plans and maps required to be filed, if plans and maps larger than 11" x 17" are submitted for review purposes, the larger plans and maps will not be retained by the Board. 785:25-5-4. Additional report information An engineer's report giving details necessary for analysis of the structure and appurtenants shall be submitted with the plans and specifications. Included as a part of the report shall be the following: (1) Formula and assumptions used in design: (2) Hydrologic data used in determining runoff from the drainage areas including copies of any records that the applicant has of flood flows and precipitation for the region; (3) Foundation and materials investigations; and (4) All other information which would aid in evaluating the design. 785:25-5-5. Notice of application (a) Notice preparation (1) After an application has been duly filed and accepted, the Board may require that applicants for permits involving significant and high hazard-potential dams publish notice as it instructs. If such notice is required, a notice will be prepared by the Board and include information describing the application, the name and address of the applicant and opportunities for public comment. (2) The notice will be mailed to the applicant with a letter of instructions as to the publication. Prior to publication the applicant shall check the notice for any errors. (b) Publication in newspaper (1) The notice of application, if required, shall be published once a week for two (2) consecutive weeks on the dates designated by the Board in a newspaper having general circulation in the county where the dam is located. (2) The last notice shall be published at least ten (10) days prior to the hearing date. (3) The applicant shall bear the cost of publication and shall see that the notice is reproduced accurately in the newspaper. (4) If the Board instructs the applicant to mail notice, such mailing shall be by certified mail, return receipt requested. UNOFFICIAL 785:25 Page 12 of 20 [Source: Amended at 9 Ok Reg 1677, eff 5-11-92] 785:25-5-6. Affidavit of notice publication and mailing (a) Affidavit of publication required. If the Board has required publication of notice, then the applicant shall file the sworn statement of the publisher with the Board before the application is considered by the Board. The affidavit shall state the dates on which the notice was published in the newspaper. (b) Failure to furnish affidavit. Failure to furnish evidence of publication or of mailing of the notice in the manner required on or before the date the Board considers the application or may be deemed evidence of abandonment of the application. [Source: Amended at 9 Ok Reg 1677, eff 5-11-92] 785:25-5-7. Public Comment (a) Any interested person may submit written comments on any application. (b) If the Board determines there is significant public interest in an application, it may schedule a public meeting to receive oral comments. Any interested person may appear and present comments. (c) The Board shall consider the public comments when evaluating the application, and shall respond or prepare and publish a response to those comments, and may direct the applicant to respond. [Source: Amended at 9 Ok Reg 1677, eff 5-11-92] 785:25-5-8. Approval or denial of application. (a) After evaluating the application, if it is determined that the proposed construction, enlargement, alteration, or repair of any dam is safe and not a menace to life and property and is in conformity with all statutory requirements and the rules in this Chapter, said application shall be approved by the Board upon such conditions as the Board may prescribe. (b) If it is determined that the proposed construction, enlargement, alteration, or repair of any dam is unsafe and a menace to life and property, [82:105.2] said application shall be denied by the Board. (c) The applicant shall be notified in writing of the Board's decision (d) If the application is approved, no impoundment of water by the dam may be made until all additional requirements of these rules and regulations are met unless the approved construction is for an existing dam and the construction may be carried out without emptying the water in the reservoir. (e) The applicant shall commence construction within two (2) years after the date of approval of the plans and specifications or the approval will be deemed to have lapsed and shall thereafter be null and void, provided that the applicant may request an extension of time to commence such construction and if the extension is granted, the approval will not be deemed to lapse during the time extended. SUBCHAPTER 7. POST APPROVAL ACTIONS Section 785:25-7-1. Inspection during construction 785:25-7-2. Inspection fee 785:25-7-3. Deficiencies during and after construction 785:25-7-4. Supervision of construction by owner 785:25-7-5. Changes to plans and specifications after approval 785:25-7-6. Notice of completion and filing of supplementary drawings or descriptive matter 785:25-7-7. Warning and evacuation plans 785:25-7-8. Certificate of completion UNOFFICIAL 785:25 Page 13 of 20 785:25-7-1. Inspection during construction During the construction, enlargement, repair, alteration, or removal of any dam or reservoir, periodic inspections may be made by the Board and the owner shall be required to perform at his expense such works or tests as necessary to disclose information sufficient to enable the Board to determine that substantial conformity with approved plans and specifications is being secured, which shall include adequate inspection, at owner's expense, to satisfy the Board of substantial compliance to approved plans, drawings, and specifications. 785:25-7-2. Inspection fee (a) Fees for any such inspection must be paid by the owner upon submission of an itemized statement by the Board. (b) Fees for inspections not paid by the owner within thirty (30) days after notice by the Board, shall be a lien against any property of such owner, to be recovered by suit instituted by the District Attorney of the county at the request of the Board. Such liens shall be superior in right to all mortgages or other encumbrances, except ad valorem tax liens, placed upon the land and the water appurtenant thereto or used in connection therewith. [82:105:27] 785:25-7-3. Deficiencies during and after construction (a) If, after any inspections, investigations, or examinations, or at any time after completion, it is found that amendments, modifications, or changes to the work performed pursuant to the approved plans and specifications are necessary to protect life and insure safety of the dam or to meet acceptable dam safety engineering practices, including those found in references set forth in 785:25-3-4, the owners shall be required to submit a revised application. (b) If conditions are revealed which will not permit the construction of a safe dam or reservoir, the prior approval may be revoked or modified by the Board after notice and hearing. (c) After the inspection, investigation, or examination, the Board shall, in a report to the owner, specify the deficiencies and allow a reasonable time for correcting the deficiencies. [Source: Amended at 9 Ok Reg 1677, eff 5-11-92] 785:25-7-4. Supervision of construction by owner After receiving approval of plans and specification, supervision of construction by the owner shall be as follows: (1) The work of construction, enlargement, repair, alteration or removal of dam or reservoir, for which approved application, plans, drawings, and specifications are required, shall be under the responsible charge of an engineer as defined in 785:25-5-2 who shall certify, upon completion and prior to impoundment of any waters, that such construction, enlargement, repair, alteration, or removal was done in accordance with approved plans, drawings, and specifications. (2) Final approval in writing by a United States governmental agency shall be required for those structures designed by and/or constructed under the supervision of personnel of that agency. 785:25-7-5. Changes to plans and specifications after approval (a) If during construction, enlargement, repair, alteration, or removal of any dam or reservoir, it is found that amendments, modifications, or changes that increase the normal or maximum water elevations, increase spillway releases or discharges, or that increase potential damages downstream will need to be made to the plans and specifications as previously approved by the Board, an amended application including maps, plans, drawings, and specifications shall be submitted to the Board for approval. UNOFFICIAL 785:25 Page 14 of 20 (b) The owner may be required to publish notice of the date, place and time when the Board will consider the matter as was done for the original application. (c) Other amendments, modifications or changes shown in as-built plans and specifications may be accepted by Board staff. [Source: Amended at 9 Ok Reg 1677, eff 5-11-92] 785:25-7-6. Notice of completion and filing of supplementary drawings or descriptive matter Immediately upon completion of a new dam or reservoir or enlargement or repair of a dam or reservoir, the owner shall give notice of completion and as soon thereafter as possible shall file supplementary drawings or descriptive matter showing or describing the dam or reservoir as actually constructed, including the following: (1) A record of all grout holes and grouting; (2) A record of permanent location points and bench marks; (3) A record of tests of concrete soils, or other materials used in the construction of the dam or reservoir; and (4) Any other items which may be of permanent value and have a hearing on the safety and performance of the dam or reservoir. 785:25-7-7. Emergency action plans (a) Owners of existing or proposed dams classified as high hazard potential, regardless of the size of such dams, and any other dam as determined by the Board, shall create and maintain an EAP that utilizes the recommendations, as determined by the Board, of the "Federal Guidelines for Dam Safety, Emergency Action Planning for Dam Owners," published August 2004 by the Federal Emergency Management Agency. The owner shall submit a copy of the EAP to the Board. (b) Owners shall annually review their EAPs to assure they are still accurate and applicable, and submit any updates to the EAPs to the Board. 785:25-7-8. Certificate of completion (a) Issuance; revocation; amendments. Certificates of completion shall be issued and may be revoked or amended as follows: (1) Upon filing of notice of completion of works by the applicant, the Board shall, within sixty (60) days, inspect or cause the dam to be inspected. The Executive Director shall approve the issuance of a certificate of completion if, based on the certification from the engineer in the Notice of Completion, the dam or reservoir is safe to impound water within the limitations prescribed in the certificate. However, no certificate of completion shall be issued until receipt of fee for certificate and all invoiced filing and inspection fees. (2) Every certificate of completion issued shall contain the date of approval of plans and specifications for the dam, date construction was completed on said dam, and [82:110.8] any such terms and conditions as the Board may prescribe. The Board may revoke any such certificate whenever it is determined that the dam constitutes a danger to life and property. Whenever such action is necessary to safeguard life and property, the terms and conditions of any such certificate may be amended and a new certificate issued containing the revised terms and conditions. (3) Certificates of completion of works from the . . . Board shall be required before any water may be impounded by a new dam or before water may be impounded at an elevation higher than that previously authorized by the Board at an existing dam which has been modified [82:110.8] UNOFFICIAL 785:25 Page 15 of 20 (b) Notice and action. After the issuance of the certificate of completion, the Board shall provide notice to the owner, allowing opportunity for a hearing, prior to the issuance of any order revoking or modifying the previous Board certificate. [Source: Amended at 10 Ok Reg 3287, eff 6-25-93] SUBCHAPTER 9. ACTIONS AFTER CONSTRUCTION Section 785:25-9-1. Inspections of dams 785:25-9-2. Records and reports of owner 785:25-9-3. Correcting deficiencies (not creating imminent peril) 785:25-9-4. Notice and action (Revoked) 785:25-9-5. Correction of deficiencies creating imminent peril 785:25-9-6. Request for inspection of dams by other parties 785:25-9-7. Recovery of costs and expenses 785:25-9-8. Emergency repairs 785:25-9-1. Inspections of dams (a) Oversight vested in Board. Oversight of the maintenance and operation of constructed dams and reservoirs insofar as necessary to safeguard life and property from injury by reason of the failure thereof is vested in the Board. (b) Periodic inspections. Except for low hazard potential dams, owners are required to have their dams inspected by qualified persons periodically according to a schedule prepared by the Board to meet the requirements of paragraphs (1) and (2) of this subsection and shall include review of the Emergency Action Plan and of the operation and maintenance manual to assure they are still accurate and applicable. Periodic inspections of dams shall be scheduled according to hazard potential classifications as follows: (1) High hazard. High hazard potential dams shall be inspected at least once annually. (2) Significant hazard. Significant hazard shall be inspected at least once every three years. (3) Low hazard. Low hazard potential dams shall be inspected at least once every five years, which inspection shall be conducted by the owner and shall consist of a review of the hazard classification on forms provided by the Board. (c) Expense of periodic inspections. Periodic inspections shall be at the owner's expense (except for low hazard potential periodic inspections) and shall be conducted by a Registered Professional Engineer hired by the owner who shall have training and/or construction of dams and reservoirs, or by an engineer of any United States governmental agency acting in his official capacity. Provided that inspections of low hazard classification dams may be conducted by persons who are not Registered Professional Engineers but who are trained in inspecting dams. If a periodic inspection is conducted by the owner or his representative, a written inspection report shall be submitted to the Board not later than 30 days after the inspection and shall contain information as set forth in a Board's hazard verification report. (d) Unscheduled inspections. Unscheduled (non-periodic) inspections such, as those conducted in response to complaints, after major heavy precipitation events or in emergency situations, may be conducted by Board staff, or the Board may require the owner to conduct and unscheduled inspection at the owner’s expense. No fee for such inspection shall be due, provided that a request for inspection by other parties shall be governed by 785:25-9-6. (e) United States dams not subject to inspection. Any dam constructed by the United States or its duly authorized agencies shall not be subject to inspection while under the supervision of officers or the United States. [82:105.27] (f) Board to notify when inspection due; violation. The Board shall notify persons shown by its records to own the dam of the date the periodic inspection of the dam is due. Such notice UNOFFICIAL 785:25 Page 16 of 20 shall require the owner to advise the Board by a date specified when an engineer retained by the owner will conduct the inspection. Failure to so notify the Board or to have the inspection completed shall constitute a violation of Board rules. [Source: Amended at 10 Ok Reg 3287, eff 6-25-93; Amended at 11 Ok Reg 2931, eff 6-13-94; Amended at 12 Ok Reg 2687, eff 7-1-95] 785:25-9-2. Records and reports of owner (a) The owner of a dam or reservoir or his agent shall fully and promptly advise the Board by telephone or any sudden or unprecedented flood or unusual or alarming circumstances or occurrence affecting the safety of the dam or reservoir. Within ten (10) days after such flood event or circumstance, the owner or owner's agent shall provide a written report of any damages to the dam and of the need to make any repairs. (b) The Board may require owners to keep records of and to report on maintenance, and staffing of any dam or reservoir if, in the opinion of the Board, such records and reports are necessary to safeguard life and property. [Source: Amended at 10 Ok Reg 3287, eff 6-25-93] 785:25-9-3. Correction of deficiencies (not creating imminent peril) (a) When an owner fails, neglects or refuses to comply with the Oklahoma Dam Safety Act, rules of this chapter, or orders of the . . . Board, and there is no imminent peril to the public health or welfare shown the Board may, after notice and opportunity for hearing, issue an order requiring such owner to take whatever action the Board deems necessary to place the dam in a safe condition, meet the requirements of the Oklahoma Dam Safety Act, rules of the Board, or the previous orders of the Board [82:110.10]. (b) Actions which can be ordered may include but are not limited to lowering the level of or removing all water in the reservoir, providing an adequate warning to the public downstream, repair or modification of the existing dam after having the appropriate application for approval of plans and specifications granted, cease all construction work on a dam, and implementation of an appropriate operation and maintenance plan [82:110.10]. (c) If after such hearing it shall be determined to order such amendments, modifications or changes, the owner shall submit, if necessary under 785:25-5-1, plans and specifications for Board approval. Upon approval of the plans and specifications, the Board shall direct the time within which such modification, alteration, or construction shall be completed. (d) In determining whether amendments, modifications or changes are necessary to protect life and insure safety of the dam, the Board shall take into consideration the possibility that the dam and reservoir might be endangered by overtopping, seepage, settlement, erosion, cracking, earth movement, or other conditions which exist in any area in the vicinity of the dam or reservoir. (e) Amendments, modifications or changes may include routine maintenance items that do not require plans and specifications, such as removal of trees on an earthen embankment, establishing vegetation cover to prevent erosion, or updating a warning and evacuation plan, etc. Amendments, modifications or changes may also include alterations or repairs which require submittal and approval of plans and specifications, including but not limited to changing the spillway design capacity, rebuilding embankments, etc. [Source: Amended at 9 ok Reg 1678, eff 5-11-92; Amended at 10 Ok Reg 3287, eff 6-25-93] 785:25-9-4. Notice and action (Revoked) [Source: Revoked at 10 Ok Reg 3287, eff 6-25-93] Agency Note (1): The language in 785:25-9-4 has been moved to 785:25-7-8(c). 785:25-9-5. Correction of deficiencies creating imminent peril UNOFFICIAL 785:25 Page 17 of 20 (a) When an owner fails, neglects or refuses to comply with the Oklahoma Dam Safety Act, rules of this Chapter, or orders of the Board, and there is an imminent peril to the public health or welfare shown, the Executive Director of the Board, or Assistant Director in the absence of the Executive Director, may, without notice or opportunity for hearing, issue an emergency order requiring such owner to take actions the Board deems necessary to place the dam in a safe condition. Such emergency order shall indicate the finding of imminent peril and shall specify the actions that are to be taken immediately. The order shall also specify a time and place for hearing to be held after such actions are taken. [82:110.10]. In determining whether an imminent peril to the public health or welfare exists, the Board may consider the following: (1) The condition of any dam or reservoir is so dangerous to the safety of life or property as not to permit time for the issuance and enforcement of an order after notice and hearing relative to maintenance or operation; (2) Passing imminent floods threaten the safety of any dam or reservoir. (b) The Board may, if the owner cannot be served or is otherwise unable to act, immediately employ remedial measures. The remedial measures the Board may take in such an emergency include but is not limited to any of the following: (1) Lower the water level by releasing water from the reservoir; (2) Completely empty the reservoir, or (3) Take such other steps as may be essential to safeguard life and property. (c) The cost and expenses of the remedial measures taken by the Board, including cost of any work done to render a dam or reservoir or its appurtenances safe, shall be recoverable by the State from the owner by action brought by the Board in the district court of the district wherein the dam or reservoir or any part thereof is situated. [Source: Amended at 10 Ok Reg 3287, eff 6-25-93] 785:25-9-6. Request for inspection of dams by other parties Upon the request of any party, accompanied by the estimated cost of inspection, the Board shall cause any alleged unsafe works to be inspected. If the works are found to be unsafe, the money deposited by such party shall be refunded and the fee for inspection shall be paid by the owner of such works. [82:105.27] [Source: Amended at 11 Ok Reg 2931, eff 6-13-94] 785:25-9-7. Recovery of costs and expenses The costs and expenses incurred by the Board for inspection of any dam found to be unsafe shall be paid by the owner of such works and if not paid by the owner of the dam within thirty (30) days after the decision of the Board shall be a lien against any property of such owner and be recoverable by the State from the owner by suit instituted by the District Attorney of the county at the request of the Board. Such liens shall be superior in right to all mortgages or encumbrances, except ad valorem tax liens placed upon the land and the water appurtenant thereto or used in connection therewith. [82:105.27] 785:25-9-8. Emergency repairs (a) If conditions exist which may cause loss of life if repairs are not made immediately, emergency repairs may be made by the owner without prior submittal of the plans and specifications required under 785:25-5-1. (b) The Board shall be notified of the emergency and the repairs to be made within 48 hours and plans and specifications shall be furnished to the Board for review as required in 785:25-5-1 as soon as possible. 785:25-9-9. Breach analysis for existing dams UNOFFICIAL 785:25 Page 18 of 20 If an existing dam does not have a breach analysis, and a failure might put lives at risk downstream, then after the next regularly scheduled inspection the Board’s Engineer may direct the owner to provide a breach analysis and breach inundation map, utilizing modeling and analysis guidelines provided by the Board, and according to a reasonable schedule of compliance. 785:25-9-10. Reclassification of the hazard-potential class of a dam (a) The Board may reclassify the hazard-potential classification of a dam at any time based on an inspection and downstream hazard evaluation. (b) If the Board determines that the hazard-potential class of a dam should be increased to a greater hazard-potential classification, then the Board shall notify the owner of that finding and of the upgrade options that are available, and set a reasonable deadline, based on the circumstances, for the owner to: (1) file an application to upgrade the dam to meet the requirements for a greater hazardpotential classification; or (2) seek an individual proceeding to contest the finding: or (3) perform a breach analysis and inundation mapping or, for existing dams that lack a breach analysis, through the use of acceptable mathematical computations applied to the downstream area from the dam to a point where the necessary design flood and breach is contained within the main stream channel, utilize modeling and analysis guidelines provided by the Board to show the dam should not be reclassified to the greater hazard-potential classification. 785:25-9-11. Upgrading dams due to downstream development (a) Alternatives. Instead of upgrading the dam using structural methods, an owner may seek to implement alternative methods. Such alternative methods shall include but is not limited to the following: (1) a current breach analysis and hydrologic study that demonstrates a lesser hazardpotential classification is correct; or (2) a current breach analysis and design flood analyses that demonstrate existing downstream developments would not be adversely affected by more than one foot difference between breach and non-breach simulations in the affected area, or records showing the downstream development has been dedicated to non-residential and noncommercial use; or (3) a plan to permanently remove the dam. (b) Schedule of Compliance. An owner may seek a compliance schedule with the Board that sets the timeframes for various stages of work to be performed. In considering such applications to upgrade on a compliance schedule the Board shall evaluate whether the current dam will not significantly affect the public safety during the compliance period. SUBCHAPTER 11. ADMINISTRATIVE PENALTIES AND PROCEDURES Section 785:25-11-1. Applicability and authority 785:25-11-2. Notice of violation and proposed assessment 785:25-11-3. Determined amount of penalty 785:25-11-4. Procedures for penalty assessment 785:25-11-1. Applicability and authority (a) The Board may impose administrative penalties against owners of dams who fail, refuse or neglect to comply with the provisions of the Oklahoma Dam Safety Act, rules of the Board UNOFFICIAL 785:25 Page 19 of 20 promulgated pursuant to the Oklahoma Dam Safety Act, and orders of the Board. Such administrative penalties shall be imposed only after notice and opportunity for hearing on the proposed imposition of such penalties [82:110.10]. (b) The notice and opportunity for hearing required by this Section may be combined with the notice and hearing required in [82:110.10] 785:25-9-3. (c) The penalties shall not exceed Five Hundred Dollars ($500.00) per day for each violation [82:110.10]. (d) Each day a violation continues shall constitute a separate violation [82:110.10] [Source: Added at 10 Ok Reg 3287, eff 6-25-93] 785:25-11-2. Notice of violation and proposed assessment The notice of proposed assessment of administrative penalties shall inform the respondent of the provisions of the Oklahoma Dam Safety Act or of the rule or order of the Board at issue and the proposed amount of the penalty. A letter, petition, notice of violation, consent order or final order may constitute a notice of proposed assessment for purposes of initiating administrative penalty proceedings if it meets the requirements of this section. [Source: Added at 10 Ok Reg 3287, eff 6-25-93] 785:25-11-3. Determining amount of penalty In setting the administrative penalty amount, the Board may consider the following: (1) The nature, duration and number of previous instances of failure by respondent to comply with requirements of law relating to dam safety and requirements of Board rules and orders. (2) The efforts of the owner to correct deficiencies or other instances of failure to comply with the requirements of Board rules and orders subject of the proposed penalty. (3) The cost of carrying out actions required to meet the requirements of law and Board rules and orders; (4) The size and hazard classification of the dam; (5) Other factors deemed appropriate by the Board. [Source: Added at 10 Ok Reg 3287, eff 6-25-93] 785:25-11-4. Procedures for penalty assessment (a) The notice of proposed assessment of administrative penalties shall specify a time, date and place of a hearing. (b) Failure of respondent to appear at the hearing shall be deemed to constitute an agreement with the imposition of the penalty in the amount proposed as set forth in the notice, and proposed findings, conclusions and order shall not be prepared in that instance. The Board and respondent may also agree to an informal disposition of the matter. In either situations, the matter shall be presented to the Board for consideration of entering a final order assessing the administrative penalty. (c) The administrative penalty is due and payable immediately upon issuance of the final order, unless otherwise provided therein. (d) If the Board believes that violations are continuing after issuance of the administrative penalty order, it may seek the issuance of additional orders to assess penalties occurring in the period after issuance of the previous assessment orders. [Source: Added at 10 Ok Reg 3287, eff 6-25-93] UNOFFICIAL 785:25 Page 20 of 20 APPENDIX A. JURISDICTION OF BOARD BY SIZE AND HAZARD CLASSIFICATION Oklaho ma o o R Dam Safety • F A C WT SatHeEr E Tes urces B ard Dam Safety Fact Sheet • Oklahoma Water Resources Board • (405) 530-8800 • www.owrb.ok.gov The Oklahoma Water Resources Board (OWRB) coordinates the state’s Oklahoma Dam Safety Program to ensure the safety of more than 4,600 of our dams in the state, especially those that could impact downstream life and property. The most common requirements of the Dam Safety Program are: * Yearly inspections for “High-hazard” dams (likely to cause loss of human life) * Inspections every 3 years for “Significant-hazard” dams (likely to cause high economic loss) * Inspections every 5 years for “Low-hazard” dams (likely to cause minimal economic loss) * Application to construct a new dam * Approval of plans for modification of an existing dam * Emergency Action Plan for High-hazard dams (see below) Training - The Dam Safety Program coordinates periodic training sessions and workshops on dam safety issues and regulations for dam owners and engineers. OWRB strongly encourages such persons to attend these valuable sessions (schedules are posted on our website*) Liability - It is important to be aware that any person or company that owns, operates, or maintains a dam is liable for some or all damages due to a failure of that dam even if an unsafe condition existed prior to a new dam owner’s term of ownership. Thus, the potential owner must carefully inspect the structural integrity of any dam prior to purchase and then inspect, maintain, and repair it thereafter. Small Dams - Construction application may not be necessary if the dam will be less than 25 feet in height above the stream bed or if the lake impounded by the dam will less than 50 acre-feet of water; however, approval is required irregardless of size if there are houses or habitable structures located below the dam. If you plan to construct a dam always check with a professional engineer, the NRCS, or with the OWRB Dam Safety Program engineer before you begin construction to determine if you need to file an application with the State. Emergency Action Plans It is the responsibility of each high-hazard dam owner to develop an Emergency Action Plan (EAP) tailored specifically to that dam. The EAP assigns critical roles including surveillance, notification, and identification of the dam break flood zone as well as develop a critical contact list in order to protect downstream lives and property. A written EAP must be submitted to and approved by the OWRB and subsequently filed with the local Civil Defense authorities. The OWRB publication, “Emergency Action Plan Guidelines for High Hazard–Potential Dams” is strongly recommended for dam owners. The Guideline and a fillable EAP form are available on OWRB’s website*. Dam Safety Inspections The regular inspection of dams is the heart of your care and maintenance program. Early detection and remedy are essential for preserving the integrity of the dam. Technical inspections must be performed by professional engineers familiar with the design and construction of dams and should include assessments of structure safety. Maintenance inspections are performed more frequently than technical inspections in order to detect, at an early stage, any developments that may be detrimental to the dam. Downstream hazard verification inspections must also be performed to determine if there has been any construction of homes, building, or other structures downstream of their dam which could raise the dam’s hazard classification. This has important implications for the dam owner as it could result in a change of how often the dam must be inspected and require structural modifications to the dam. For further information, OWRB Dam Safety publications and online forms visit our website at: * www.owrb.ok.gov/damsafety.php NRCS Sugar Creek Site # 44 dam, Caddo Cnty, OK washed out from heavy rains OKLAHOMA Citation Oklahoma dam safety laws are contained in 82 O.S. § 110, last amended in 1992. Regulations are found in the Oklahoma Water Resources Board Rules, Chapter 25, originally adopted in 1973 and last revised in 1997. Definitions/Dam Classifications Dam means any artificial barrier, together with appurtenant works, which does or may impound or divert water (Rules 785:25-1-2). A dam is regulated if it is 25 feet or more in height or has an impounding capacity of 50 acre-feet or more. No obstruction determined to be designated primarily for road fill shall be considered a dam (Rules 785:25-3-1[6]). Dam height is measured from the natural bed of the stream or watercourse at the downstream toe of the barrier or from the lowest elevation of the outside limit of the barrier if it is not across a stream channel or watercourse, to the maximum possible water storage elevation. Dam classifications are based on size of the structure and the potential for hazards (Rules 785:25-3-3). Size Classification Size Maximum Storage (ac-ft) Maximum Height (ft) Small less than 10,000 less than 50 Intermediate between 10,000 - 50,000 between 50 - 100 Large greater than 50,000 greater than 100 Hazard Potential Classification Category Loss of Life Economic Loss Low none minimal Significant none appreciable High yes excessive Jurisdiction/Powers of Department State dams fall under the jurisdiction of the Oklahoma Water Resources Board, hereafter referred to as "the Board". Title 82 of the Oklahoma Statutes 1981, section 1085.2, as amended, requires the Board to adopt rules and regulations deemed necessary to the exercise of any powers conferred upon it. The Board is empowered to issue permits and review and approve applications for the construction, enlargement, alteration, or repair of any dam (Rules 785:25-5-1). The Board's responsibility over dams shall be limited to dams with a height of twenty-five feet or more, or those with an impounding capacity of fifty acre-feet or more (Rules 785:25-3-1). The Board is empowered to inspect dams during construction (Rules 785:25-7-1) and after construction is completed (Rules 785:25-7-3). The Board has the power to cite noncompliance and call for remedial work (Rules Chapter VII730.4) and may invoke judicial actions if necessary (Rules 785:25-11-1). The Board has the power to immediately employ remedial measures in the event of a dam emergency (Rules 785:25-9-5). Permit/Approval Process A filing fee must be submitted with each application to construct, enlarge, alter, or repair a dam, based on estimated cost of construction (Rules Chapter III305.5). Estimated Cost Filing Fee $20,000 or less $ 100.00 $20,001-$99,999 $200.00 $100,000-$999 999 $500.00 $1,000,000 or more $1,000.00 Plans and specifications are to be prepared by a registered professional engineer (Rules 785:25-5-2). Applicants for a permit must submit an application upon printed forms, which will be furnished by the Board upon request. The maps, plans, drawings, and specifications of the proposed work along with the filing fee shall form part of the application (Rules 785:25-5-1). In addition, an engineer's report giving details necessary for analysis of the structure and appurtenances shall be submitted with the plans and specifications (Rules 785:25-5-4). After an application has been filed, a notice will be prepared by the Board setting forth the time, date, and place for hearing the application. Protests regarding the application may be heard at this time. The Board will then render its decision (Rules 785:25-5-7). Rules 785:25-3-5 and 785:25-3-6 establish minimum design standards as well as minimum spillway performance standards which all dams are required to meet. The owner is required to pay all fees and is responsible for any remedial work (Rules 785:25-9-5). Inspection Process State Supervision over the maintenance and operation of constructed dams and reservoirs insofar as necessary to safeguard life and property is vested in the Board (Rules 785:25-9-1). The rules give the Board responsibility for carrying out routine inspections of every dam under their jurisdiction. Periodic inspections of dams shall be scheduled according to hazard classification as follows: High Hazard - At least once annually Significant Hazard - At least once every three years Low Hazard - At least once every five years Costs and expense incurred by the Board for inspecting a dam found to be unsafe are the responsibility of the owner. A lien shall be placed on the property if the owner does not pay within 30 days of the Board's decision and expenses shall be recovered by suit. Owner Periodic inspections shall be at the owner's expense and shall be conducted by Board staff, a registered professional engineer, or an engineer of any United States governmental agency acting in his official capacity. Some low hazard dams may be exempt from the periodic inspection (Rules 785:25-9-1). Rule 785-25-9-2 requires the owner or his agent to "fully and promptly advise the Board of any sudden or unprecedented flood or unusual or alarming circumstances or occurrence affecting the safety of the dam or reservoir". During the construction, enlargement, repair, alteration, or removal of any dam, periodic inspections may be made by the Board and the owner shall be required to perform at his expense such works or tests as necessary to disclose information sufficient to enable the Board to determine that substantial conformity with approved plans and specifications is being secured (Rules 785:25-7-1). Violations/Penalties Every person shall be guilty of a misdemeanor who violates any of the provisions of the laws or of any order, rule, or regulation of the Board issued pursuant thereto, where a copy of the order, rule, or regulation has been served upon said person by certified mail and said person fails to comply therewith within the time provided, or within ten days of such service if not otherwise provided. In the event of a continuing violation, each day that the violation continues constitutes a separate offense (Rules 785:25-1- 3). Emergencies The Board may, without notice and hearing issue an emergency order requiring remedial measures to be taken necessary to protect life and property. If the owner cannot be served or is otherwise unable to act, the Board may immediately employ remedial measures. In applying remedial measures, the Board may in emergency do or cause to be done any of the following: (a) Lower the water level by releasing water from the reservoir, (b) Completely empty the reservoir, or (c) Take such other steps as may be essential to safeguard life and property. The cost and expenses of the remedial means, including cost of any work done to render a dam safe, shall be recoverable by the State from the owner by action brought by the Board in the district court of the district wherein the dam is situated (Rules 785:25-9-5). Rule 785:25-7-7 requires owners of existing or proposed dams classified as high hazard to provide an adequate warning system and evacuation plan to protect downstream lives and property. The plan is to be approved by and filed with the local Civil Defense authorities. The plan must also be filed with the Board. Liability Owners of dams have the responsibility to provide for the safety of such works by making any necessary changes to put the works in a safe condition (Rule 785:25-11-1). Title 51.05 Supp. 1990 Section 155 exempts the state from liability if a loss or claim results from inspection power including the failure to make an inspection or the completion of an inadequate or negligent inspection. Oversight As allowed by and subject to compliance with the requirements imposed under the Oklahoma Administrative Procedures Act (75 O.S. 1981, Sections 301326), any interested party may request rehearing, reopening or reconsideration of any final Board action, decision or Order (Rule 785:4-9-3). Miscellaneous Dams constructed by the United States or its duly authorized agencies shall not be subject to inspection while under the supervision of the officers of the United States (Rules 785:25-9-1). The Oregon Administrative Rules contain OARs filed through October 15, 2010 WATER RESOURCES DEPARTMENT DIVISION 20 DAM SAFETY 690-020-0000 Purpose and Applicability (1) These rules describe the standards and requirements under which the department will administer and enforce the design, construction, maintenance, inspection, and fees regarding dams in Oregon. The purpose is to provide the guidance necessary for dams to be constructed and operated in a manner that will ensure the protection of life and property and to provide the department with the resources necessary to manage and support the construction and safe operation of dams in accordance with these rules. (2) These rules apply to: (a) Dams that are not subject to ORS 540.350–540.390 as described in 540.400. (b) Dams that are subject to ORS 540.350–540.390 and which exceed the statutory limits as described in ORS 540.400(1) & (2). (3) These rules do not apply to metal or reinforced concrete water storage tanks or various types of tanks that are part of water treatment facilities. Stat. Auth.: ORS 540.350 - 540.400, 536.050 Stats. Implemented: ORS 183, 540, 536 Hist.: WRD 12-1986, f. & ef. 10-3-86; WRD 12-1994, f. & cert. ef. 11-7-94; Renumbered from 690-020-0021, WRD 7-2009, f. 12-7-09, cert. ef. 1-1-10 690-020-0021 [Renumbered to 690-020-0000] 690-020-0022 Definitions The following definitions apply in OAR 690, Division 20: (1) “Abutment” means a natural valley or canyon side against which the dam is built; (2) “Acre-foot” means the equivalent volume of one acre covered with one foot of water (325,900 gallons); (3) “Conduit” means a closed conveyance used to release water through a dam; (4) “Cutoff Trench” means a trench excavated beneath the dam foundation and backfilled with low permeability material to retard water seepage; Water Resources Dept._690_020 Page 1 of 7 http://arcweb.sos.state.or.us/rules/OARS_600/OAR_690/690_020.html 11/26/2010 (5) “Dam” means a hydraulic structure built above the natural ground grade line that is used to impound water. Dams include wastewater lagoons and other hydraulic structures that store water, attenuate floods, and divert water into canals; (6) “Dam Crest” means the top of the dam; (7) “Department” means the Oregon Water Resources Department; (8) “Director” means the Director of the Oregon Water Resources Department; (9) “Embankment” means an engineered earth fill; (10) “Emergency Spillway” means an overflow structure constructed to bypass flood water and prevent overtopping the dam crest. Often, dams have two spillways. The lower elevation spillway that spills first is referred to as the principle spillway. The higher elevation spillway is referred to as the emergency spillway; (11) “Foundation” means the ground surface upon which a dam is constructed; (12) “Freeboard” means the vertical distance between the designed high-water level in the reservoir and the dam crest; (13) “Gate” or “Valve” means a permanent device for regulating water flow through the dam; (14) “Hazard Rating” means the rating established by the department for a large dam that pertains to the potential level and degree of damage to life and property downstream of a dam in the event dam failure results in a catastrophic release of water; (15) “Large Dam” for dam safety purposes, means a dam with a height of 10 feet or more and impounding 3,000,000 gallons (9.2 acre-feet) or more of water; (16) “Significant dam work” means an activity to repair, rehabilitate, enlarge or otherwise alter a dam in which: 1) at least 30% of the fill material is impacted by the activity, 2) a spillway is being enlarged or repaired that affects the height or hydraulics of the spillway, 3) dam height and/or reservoir size is being increased, 4) a low level outlet conduit or inlet gate is being reworked with excavation or 5) any other activity that could affect the integrity of the dam or its auxiliary works; (17) “Small dam” for dam safety purposes, means a dam with a height of less than 10 feet or impounding less than 3,000,000 gallons (9.2 acre-feet) of water; and (18) “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. Stat. Auth.: ORS 183 & 540 Stats. Implemented: ORS 183 & 540, 536 Hist.: WRD 12-1986, f. & ef. 10-3-86; WRD 7-2009, f. 12-7-09, cert. ef. 1-1-10 690-020-0025 General Requirements for all Dams (1) The director may require any information or data in addition to that outlined herein which the director finds necessary for determining the safety of the proposed structure. (2) Whenever possible, precipitation and runoff records shall be submitted as part of the design for new or significant dam work on existing dams. If records are not available for the basin in which the dam is located, the hydrological/hydraulic criteria used in the design shall be submitted. (3) The director may include as part of any permit to construct a dam limitations and conditions that pertain to construction, operation, maintenance, and the protection of lives and property. These limitations and conditions become, by reference, part of the certificate and remain in effect throughout the life of the water right. (4) Approved plans and specifications for construction are, by reference, considered limitations and conditions placed on the water right permit and water right certificate. The director retains the authority to place additional limitations and conditions on the water right relative to operation and maintenance. (5) Dams constructed or operated in violation of limitations and conditions included in the permit or certificate are subject to Water Resources Dept._690_020 Page 2 of 7 http://arcweb.sos.state.or.us/rules/OARS_600/OAR_690/690_020.html 11/26/2010 restricted use and permit cancellation procedures. The certificate affirms the applicant's right to store water subject to the limitations and conditions therein. (6) An outlet conduit with a minimum diameter of 8" must be installed in any instream reservoir to permit drainage of the reservoir and for passage of flow to downstream prior rights. The director may waive this requirement if the director determines that the conduit is not needed for dam safety and will not be needed to pass flow for the benefit of other water rights, minimum perennial streamflows, or if the director determines an adequate alternative for passing flow is provided. Adequate alternatives must be capable of passing flow in sufficient quantity to satisfy downstream needs, and can include pumps, by-pass channels and siphons. Conduit material should be chosen based on design and site condition requirements. Acceptable conduit materials include reinforced concrete cylinder pipe; cast-in-place, reinforced concrete; appropriate PVC; concrete-encased corrugated metal pipe or plastic pipe; ductile iron; and cast iron. All joints should be water tight. The conduit valve should be installed at the upstream end and should be industry-manufactured with specifications consistent to the applied usage. Special provisions should be made for pressure conduits gated on the downstream end. (7) The department shall determine the height of a dam by calculating the vertical distance (measured in feet) between the center point of the dam crest relative to and above the stream channel and the lower of either the natural soil surface that was in place prior to the construction of the dam or where a channel incision exists, the bottom of the channel incision. This measurement is to be taken at the maximum section along the dam’s longitudinal axis. (8) The department shall determine water impoundment volumes (in acre-feet or millions of gallons) as follows: (a) For dams impounding water for an authorized beneficial use, the impoundment volume indicated in the area-capacity curve from the bottom of the reservoir to the spillway crest. For dams with multiple spillways, ‘spillway crest’ is referring to the crest of the principle or lower elevation spillway. (b) For wastewater treatment lagoons, the impoundment volume indicated in the wastewater lagoon plans and specifications, and (c) For diversion or flood control dams, the impoundment volume calculated at full reservoir at the dam emergency (highest elevation) spillway crest level. Stat. Auth.: ORS 540.350 - 540.400 Stats. Implemented: ORS 183, 536 & 543 Hist.: WRD 3, f. & ef. 2-18-77; WRD 12-1986, f. & ef. 10-3-86; WRD 12-1994, f. & cert. ef. 11-7-94; WRD 7-2009, f. 12-7-09, cert. ef. 1-1-10 690-020-0029 Small Dams, Recommended Minimum Standards The following information is presented for the applicant's assistance in constructing small earthfill dams: (1) It is recommended that the crest width of the dam be not less than 8 feet. (2) It is recommended that the upstream slope of the dam be no steeper than 3:1. (3) It is recommended that the downstream slope of the dam be no steeper than 2:1. (4) It is recommended that the spillway channel be constructed around the dam, not over the top of the fill. The spillway is commonly excavated in natural material and, if necessary, lined to prevent erosion. The spillway should be large enough to pass the 50-year flood flow without overtopping the dam. Assistance is available from the department in sizing the spillway. Flow passing through the spillway should be returned to the creek channel at a sufficient distance downstream to prevent erosion of the dam’s embankment. (5) It is recommended that all brush, stumps, roots, and organic matter should be cleared from the area to be occupied by the dam. All such material should also be removed from the borrow area. (6) It is recommended that the outlet pipe be encased with concrete or other method to allow for proper compaction and the prevention of uncontrolled seepage. (7) Embankment material should be spread parallel with the dam axis in layers not exceeding eight inches in thickness and adequately compacted with sheepfoot roller or other similar equipment. (8) It is recommended that prior to construction the dam owner have the dam’s potential hazard to downstream properties studied Water Resources Dept._690_020 Page 3 of 7 http://arcweb.sos.state.or.us/rules/OARS_600/OAR_690/690_020.html 11/26/2010 using methods listed in 690-020-0100. It is recommended that any dam with a potential significant or high hazard rating be designed by a registered engineer familiar with dam engineering. It is advisable for any dam nearing or surpassing the dam height or storage thresholds for a “large dam” to be designed by a registered engineer. Stat. Auth.: ORS 183 & 540 Stats. Implemented: ORS 183 & 540 Hist.: WRD 12-1986, f. & ef. 10-3-86; WRD 7-2009, f. 12-7-09, cert. ef. 1-1-10 690-020-0035 Dams Over the Statutory Limits; Minimum Engineering Design Requirements All maps, plans, and specifications for the construction of new large dams or significant dam work for existing large dams, must be prepared by a professional engineer licensed to practice in the State of Oregon. (2) Before initiating design, the engineer shall obtain design criteria from the department. (3) No newly constructed large dam shall be permitted to store water until written approval is received from the department. Approval will be given after construction has been completed and is certified by the supervising engineer to have been constructed in accordance with the approved plans and specifications. (4) Design documents shall include the following: (a) Plans: (A) Plans for dams submitted for approval must accurately portray the work to be accomplished and be of sufficient detail to adequately define all features of the project. Plans must be submitted on good-quality mylar or vellum and must be neatly and accurately drawn to a scale sufficiently large, with an adequate number of views, for the drawing to be readily interpreted. To meet the requirements of this subsection, the director may allow plans for dams to be submitted electronically. The format of the plans in terms of file type, projection and other details must be approved by the department. (B) Several sheets may be used to eliminate the necessity of large bulky drawings. No map or plan should be larger than 24 x 36 inches. The following information will be required: (i) A contour map of the reservoir site which will show the location of the dam by quarter-quarter section, township, range and tax lot; and the name and location of the stream flowing through the reservoir. Government survey lines must be indicated on this map, along with a survey tie to the dam axis from a government land corner. Area and capacity curves and/or tables of the proposed reservoir must be shown; (ii) A map of the drainage basin showing the location of the dam and reservoir and the streams within the drainage area. This map may be prepared from existing reliable topographical maps and it must include: the number of square miles of drainage area; a brief description of the area; the percentage of bare and timbered lands; and general characteristics of the watershed, whether precipitous, rolling, or comparatively flat. The estimated discharge as well as the spillway capacity at different reservoir water levels should also be provided in the plans or specifications. Extraneous information can also be included in specifications or a separate hydrology report as to not clutter up the map; (iii) A topographic map of the dam site with contour intervals not to exceed 5 feet. A plan of the dam should be superimposed on this map showing the location of spillways, outlet conduits, and other relevant auxiliary structures; (iv) A profile of the dam site taken on the axis of the dam and a profile of the spillway along its axis. The profile should also show the location of the outlet conduit and spillway. A log showing the classification of materials encountered below the surface as shown by test pits or borings; (v) A cross section of the dam at maximum section showing complete details and dimensions; (vi) Plans showing sections of the outlet conduit, control works, and spillways. These sections should be in sufficient number and detail to make definite all features of the structure. (b) Specifications. All plans for dams must be accompanied by construction and material specifications: (A) The specifications shall describe in detail the methods and/or performance criteria to be followed in performing each class of Water Resources Dept._690_020 Page 4 of 7 http://arcweb.sos.state.or.us/rules/OARS_600/OAR_690/690_020.html 11/26/2010 work and shall set forth the requirements for the various types of material to be used in permanent construction; (B) The specifications must contain a provision for supervision by the engineer during construction and for inspection by the director or director’s authorized representative at any time during the construction period; (C) The specifications must also contain a provision to the effect that plans or specifications shall not be altered or changed without the written approval of the director or the director's authorized representative. (5) Construction: Construction should be supervised by an engineer licensed to practice in Oregon. As a minimum the following notices and construction reports shall be submitted to the Department: (a) Notice of beginning of construction; (b) Notice of intent to begin placement of fill materials; (c) Completion report including test results, "as-built" drawings, and certificate of completion in accordance with approved plans and specifications. (6) During the design process for any newly constructed dams or for significant dam work to existing dams that involves potentially changing the volume or rate of water released during failure, the dam owner or owner’s representative must submit to the department an inundation analysis using methods described in 690-020-100. The department shall use this analysis to determine the hazard rating of the dam in accordance with 690-020-100. (a) If a dam is rated as high hazard, an emergency action plan is required and the plan must be reviewed and approved by the department. (b) The inundation/evacuation map for the dam must be developed using methods described in 690-020-100(2) and must be reviewed and approved by the department. Stat. Auth.: ORS 540.350 - 540.400 Stats. Implemented: ORS 183, 536 & 540 Hist.: WRD 3, f. & ef. 2-18-77; WRD 12-1986, f. & ef. 10-3-86; WRD 12-1994, f. & cert. ef. 11-7-94; WRD 7-2009, f. 12-7-09, cert. ef. 1-1-10 690-020-0039 [Renumbered to 690-020-0050] 690-020-0050 Enforcement Procedures The director shall maintain a program of inspecting existing dams. When any structure is found to be in violation of the terms and conditions of the permit or certificate or directly threatens life or property, or when any structure is found where lack of maintenance or unauthorized alterations could lead to a direct threat to life or property, the department shall notify the owner in writing of the violation and the action necessary to bring the structure up to design, operation, or maintenance standards. Failure by the owner to perform the required action may result in proceedings for one or more of the following: (1) Notice and opportunity for a contested case hearing as provided for in ORS 540.350(5). (2) Cancellation of the permit. (3) Posting of the structure to prevent storage or to limit operation until the owner has complied with the requested action required to fulfill conditions of the permit or certificate. (4) Instituting legal action by the District Attorney or Attorney General to have the facility declared a public nuisance. (5) Issuance of an order to prevent storage or to breach the embankment as provided for in ORS 540.370. (6) Any other enforcement action permitted by law. Stat. Auth.: ORS 183 & 540 Stats. Implemented: ORS 183 & 540 Hist.: WRD 12-1986, f. & ef. 10-3-86; Renumbered from 690-020-0039, WRD 7-2009, f. 12-7-09, cert. ef. 1-1-10 Water Resources Dept._690_020 Page 5 of 7 http://arcweb.sos.state.or.us/rules/OARS_600/OAR_690/690_020.html 11/26/2010 690-020-0100 Hazard Rating (1) Hazard ratings for “large dams” are classified by the department as “high hazard”, “significant hazard”, or “low hazard” as follows: (a) High Hazard: This rating indicates that if the dam fails there is a strong plausibility for loss of life. The plausibility is established because of inhabited infrastructure (such as homes and business) downstream that would be inundated to such a degree see 690-020-0100(2)(d) for specific criteria that it would put the person who inhabits the structure in jeopardy. Any factor that puts a strong probability of people being downstream in an inundation area of a dam failure shall be considered. The department shall endeavor to inspect this class of dams on an annual basis. (b) Significant Hazard: This rating indicates that if a dam fails, infrastructure (such as roads, power lines or other largely uninhabited buildings) would be damaged or destroyed due to inundation and flooding. The department shall endeavor to inspect this class of dams at least once every three years. (c) Low Hazard: This rating indicates that if the dam fails there is little plausibility for loss of life, and human infrastructure that could be affected by inundation downstream is minor or non-existent. The department shall endeavor to inspect this class of dams at least once every six years. (2) The department shall utilize inundation of infrastructure study results as a primary factor to determine the hazard rating of dams. Methods and modeling acceptable for inundation of infrastructure studies include: (a) Hydraulic Modeling: Use of one-, two-, or three-dimensional modeling software (such as HEC-RAS, FLO-2D or MIKE) and hydrologic, topographic, and other data to estimate inundation of infrastructure downstream of dams. (b) Hydrologic Routing Modeling: Use of modeling software such as HEC-HMS with hydrologic routing methods such as the Muskingum and Modified-Puls methods along with hydrologic and topographic data. (c) Simplified Methods such as SMPDBK and the Washington State Method: “Dam Breach Analysis and Downstream Hazard Classification” may be used. A dam owner may request information on these methods from the department. Use of these or other simplified methods is only to be used in hazard ratings for dams, not for emergency action planning. (d) Depth of inundation to trigger different hazard ratings: A depth of at least two feet over the finished floors of buildings or road surface of infrastructure is required to establish a “high hazard” rating. Any depth of water over the floorboards of structural buildings such as homes, barns, pump houses or storage sheds can establish a “significant hazard” rating. For roads, a depth of two feet or evidence of depth and velocity capable of creating damage can be used to establish a “significant hazard” rating. (e) Specific data, methods and results for all methods must be reviewed and approved by the department prior to revising a hazard rating. (3) The hazard rating of a dam shall remain in effect until the rating is revised by the department using one of the methods described in section 2. A dam owner may request that the department revise a hazard rating. The owner must provide information in support of the request. If the supporting information includes results and/or analysis using the methods described in subsections 2(a) or (b), the information must be prepared by an engineer licensed in Oregon and familiar with hydraulic and hydrologic modeling; if the information includes results and/or analysis using the methods described in subsection 2(c), the information must be prepared by a licensed engineer or a practicing hydrologist familiar with hydraulic and hydrologic calculations. (4) Exceptions to Hazard rating methods: (a) Small dams are not assigned a hazard rating. (b) Situations in which there are heavy recreational or other uses downstream, a dam may be rated as “high hazard” because of probable loss of life regardless of downstream infrastructure presence. Stat. Auth.: ORS 183 & 540 Stats. Implemented: ORS 183 & 536, 540 Hist.: WRD 7-2009, f. 12-7-09, cert. ef. 1-1-10 690-020-0200 Fees for Dams Water Resources Dept._690_020 Page 6 of 7 http://arcweb.sos.state.or.us/rules/OARS_600/OAR_690/690_020.html 11/26/2010 (1) Owners of a large dam shall submit to the department an annual fee in the amount and on the basis established under ORS 536.050. (2) Dam owners who fail to pay an annual fee on or before six months after the billing date may be required to pay a late fee in the amount established under ORS 536.050. (3) If a dam owner fails to pay the annual fee or late fee charged by the department, the department may, after giving the dam owner notice by certified mail, place a lien on the real property where the dam is located for the fees owed by the dam owner. (4) Dams that are subject to the annual fee include dams partially or wholly in the State of Oregon that meet the definition of ”dam” under OAR 690-020-0020. (5) Multiple large dams connected together and separated only by embankments or other manmade materials (common with sewage lagoons) will count as one dam for fee purposes. (6) Owners Exempt from Fee Requirements include: (a) Owners of a “small dam”, (b) Owners whose dams that are directly controlled or regulated for safety by an agency of the U.S. Federal Government and the agency that controls or regulates the dam has its own safety program that meets the following criteria: (A) The program must allow for control of the design and construction process for dams under their control with licensed engineers designing and reviewing any major design or repair. Copies of all design drawings and construction records should be forwarded to the department for tracking and archival purposes. (B) The program must have a regular dam inspection program that is either conducted by or directly supervised by a licensed engineer with expertise in dam safety. Formal documented dam inspections for high hazard dams should occur at least once per year. For significant hazard dams, inspections shall occur at least once every 3 years and for low hazard dams, once every 6 years. Other more frequent inspections and reports on dam conditions may be necessary depending on the condition of individual dams. Copies of mutually agreed upon inspections and reports should be forwarded to the department for archival and tracking purposes. (C) The federal agency in charge of the dam via regulation or control must also have a regular maintenance program or be able to require maintenance activity from the regulated party that will address problems discovered in the inspection program. (D) The federal agency must have a memorandum of understanding or agreement with the department that outlines how the federal agency meets the criteria in paragraphs (b)(A)–(C), and must agree to meet at least annually with the department to review the state of the federal program for continued exemption purposes. Stat. Auth.: ORS 536.050 Stats. Implemented: ORS 536.050 Hist.: WRD 7-2009, f. 12-7-09, cert. ef. 1-1-10 The official copy of an Oregon Administrative Rule is contained in the Administrative Order filed at the Archives Division, 800 Summer St. NE, Salem, Oregon 97310. Any discrepancies with the published version are satisfied in favor of the Administrative Order. The Oregon Administrative Rules and the Oregon Bulletin are copyrighted by the Oregon Secretary of State. Terms and Conditions of Use Alphabetical Index by Agency Name Numerical Index by OAR Chapter Number Search the Text of the OARs Questions about Administrative Rules? Link to the Oregon Revised Statutes (ORS) Return to Oregon State Archives Home Page Water Resources Dept._690_020 Page 7 of 7 http://arcweb.sos.state.or.us/rules/OARS_600/OAR_690/690_020.html 11/26/2010 Dam Safety in Oregon A General Guide State of Oregon Water Resources Department 725 Summer Street NE, Suite A Salem, Oregon 97301 (503) 986-0900 www.wrd.state.or.us March 2007 Contents Dam Safety in Oregon History of the Dam Safety Program............1 Responsibilities and Duties.........................3 Hazard Classifications.................................7 Permitting...................................................10 Applying for a Permit to Use Water............11 Preparing the Reservoir Application.........13 How an Application is Processed..............13 Dams Under Statutory Limits....................14 Dams Over Statutory Limits......................15 Dam Inspection...........................................19 Rating Criteria............................................20 Inspection Form..........................................21 Enforcement...............................................23 Appendices Statutory Authority....................................25 Dam Components........................................26 Glossary......................................................30 Oregon Water Resources Department www.wrd.state.or.us - Dam Safety website, forms, and administrative information. The website is updated regularly with news and events. Federal Emergency Management Agency www.fema.gov - US government agency dedicated to disaster mitigation, preparedness, and response and recovery planning. Links can be found on their website to Dam Safety and the FEMA Emergency Action Plan. This website is regularly updated with current emergency related news. Association of State Dam Safety Offi cials www.damsafety.org - ASDSO is a non-profi t organization of state and federal dam safety regulators, dam owners and operators, engineering consultants, manufacturers and suppliers, and others interested in dam safety. ASDSO’s vision is to lead the US dam safety community with a strong, unifi ed voice and effective programs and policies towards furtherance of dam safety. Bureau of Reclamation www.usbr.gov - The Bureau of Reclamation is the second largest supplier of wholesale water and hydroelectric power in the American West. They promote water conservation, recycling, and reuse. The Bureau of Reclamation is a contemporary water management agency with a strategic plan outlining numerous programs, initiatives, and activities that will help meet new water needs and balance the multitude of competing uses of water in the west. US Army Corps of Engineers www.usace.army.mil - Their mission is to provide quality, responsive engineering services to the nation including planning, designing, building, and operating water resources and other civil works projects. Navigation, fl ood control, environmental protection, and disaster response links are updated regularly. Contact Us Purpose Dam safety is an important issue of which the public needs to be familiar. This booklet has been designed to cover topics that will benefi t the public, engineers, dam owners, and watermasters. This booklet also covers Oregon’s laws pertaining to dams and a glossary of commonly used terms. History of the Dam Safety Program Dam safety laws in Oregon were first adopted in 1909, and then modified in 1927, and again in 1929 following the catastrophic failure of California’s St. Francis Dam, when the statutes were amended to their present form, more or less. Initially, the review of design plans and specifications was conducted by the State Engineer, and then by a staff engineer in the State Engineer’s Office. This one person operation continued until 1956 when the staff was increased to two-full time engineers. In 1975, further amendments to Oregon water laws merged the State Engineer’s Office and the Water Resources Board, forming the Water Resources Department and changing the title of the department head from “State Engineer” to “Water Resources Director”. The State Water Policy Review Board and oversight committee was also created, consisting of 7 members from the public appointed by the Governor. As a consequence, the authority to take enforcement actions for protection of human life and property related to Dam Safety was transferred from the State Engineer to the Water Resources Director. An inspection technician was added to the Dam Safety Program in 1978. Also, Dam Safety added five engineers with funding provided by Congress. A direct result of the increased funding allowed completion of 50 Phase I Inspections Reports for existing high hazard, non-federal dams within the state. In 1982, the program ended as federal funding was eliminated. All but two of the engineering positions and the inspection technician position were also eliminated. The name of the State Water Policy Review Board was changed to the Water 1 History of the Dam Safety Program Resources Commission in 1983, and to it was given new responsibilities for policy decisions, rule making, and management of the agency. Shortly thereafter, the Commission delegated much of its new found authority back to the Director’s Office. Until this time, Dam Safety had existed as a separate, stand alone unit. Later, Dam Safety was combined with the Enforcement Division within the agency. The program was reduced to a single Dam Safety Engineer and one technician. Watermasters were assigned routine inspection duties for existing dams in addition to their other water distribution and regulation assignments. Additionally, other program areas were assigned to the remaining Dam Safety Engineer, including Hydroelectric Facility licensing and Hydrographics. In 1990, the agency was reorganized so that Dam Safety was combined with Computer Services, GIS, Hydrographics, Hydrology, and Groundwater to form the Technical Services Division. The Hydroelectric Licensing section was moved into the Water Rights Division, however the Dam Safety Engineer was still required to manage a division with about 35 employees. In 1993, an engineer was hired as Dam Safety Coordinator to upgrade and replace the technician position that was eliminated due to retirement. For a short while, the Technical Services Division was combined with the Field Services Division, but then reverted to the previous arrangement that placed Dam Safety in the Technical Services Division. At present, the Dam Safety Engineer also serves as Division Administrator. The Dam Safety Coordinator is responsible for the management of the Dam Safety Program. 2 The Dam Safety Program is responsible statewide for the review and approval of dam designs, scheduling inspections of existing dams and reservoirs, conducting site inspections of new dam construction, and maintaining both the National Dam Inventory (NID) and the state database. It is important to realize that the ultimate responsibility for the continued safe operation of any dam or reservoir rests entirely with the dam owner(s). Oregon does not require proof of insurance before a reservoir is filled with water. Typically, water right holders own the land upon which most dams and reservoirs are built. In cases where there are no associated water rights or where the water right holder does not own the real property where the structure is situated, the State presumes the land owner also to be the owner of the dam. The Dam Safety Coordinator provides assistance to watermasters and to owners and operators of dams when questions or situations arise that require engineering advice or training. Other duties include hazard assessment of existing structures, review of emergency management plans, and review of water right transactions (applications, permits, certificates) to assure that appropriate conditions are met that will help to provide safety for downstream life and property. “To serve the public by practicing and promoting responsible water management.” Water Resources Department Mission Statement Responsibility Duties of the Dam Safety Program 3 Duties of the Dam Safety Program The Dam Safety Coordinator also performs all regular clerical and office support duties. The state is divided into four regions and twenty watermaster districts. In addition to their duties relating to regulation of water use and distribution, the watermasters assist with performing routine and regularly scheduled inspections of low hazard dams and reservoirs within their respective districts according to a schedule prepared and updated by the Dam Safety Coordinator. Approximately 8 to 10 percent of each watermaster’s time is allocated toward dam and reservoir inspections. At present, nearly 1300 dams and reservoirs are inspected at an interval of 1 to 5 years. Of those, more than 100 structures are owned, operated, or supervised by federal organizations who also maintain active dam safety programs. Some examples of these federal organizations are the Corps of Engineers, Bureau of Reclamation, and certain hydroelectric power generating facilities licensed by the Federal Energy Regulatory Commission (FERC). The Oregon Water Resources Department participates with the respective federal agencies in the inspection of those structures. 4 Responsibility The National Flood Insurance Program (NFIP) provides federally backed flood insurance in communities that comply with minimum standards for floodplain management. As an incentive, standard homeowners and commercial property located within a designated “flood zone” can receive an insurance premium rate reduction based on various activities that communities voluntarily undertake to reduce flood losses. Once enrolled in the NFIP, each participating community is evaluated based upon the number of credit points earned according to prerequisite activities listed under the NFIP’s Community Rating System (CRS). Depending on the total number of credit points, the CRS assigns a community to one of 10 classes. A maximum 45% insurance premium discount is possible if all CRS criteria are satisfied. Under CRS Activity 630, a participating community will automatically receive up to 75 credit points if their respective state has a dam safety program that meets certain criteria based on the Model Dam Safety Program recommended by the Association of State Dam Safety Officials (ASDSO). Information and guidelines contained as key components of the For more information about the Association of State Dam Safety Offi cials (ASDSO), visit the website: www.damsafety.org For more information about the National Flood Insurance Program (NFIP), visit the website: www.fl oodsmart.gov 5 Model State Dam Safety Program are broken into the following chapters: I. Legislation and Regulations II. Permitting, Design Approval and Authorization to Impound III. Inspection IV. Enforcement V. Emergency Response VI. Program Staff and Funding VII. Program Staff and Dam Owner Education and Training VIII. Dam Safety Program Public Relations Plan Presently, the Oregon dam safety program does not have authority to take corrective or emergency action if a dam owner fails to comply with an Order. Therefore, Oregon communities participating in the NFIP do not receive any credit points for the state dam safety program. In order for communities to receive this additional credit, all of the elements listed in the Model Dam Safety Program must also be included in the state’s program. 6 What Constitutes a Dam? “Dam” is not specifically defined in any of Oregon’s statutes or rules. Regardless of a legal definition per Oregon law, a dam is taken here to mean: “any artificial barrier, including appurtenant works, that impounds or diverts the flow of water.” (See Glossary) Hazard vs. Risk When considering hazard in terms of dam classification, it is important to realize that the term “Hazard” is not the same as “Risk”. For example, a large dam may be rated a high hazard structure because its location is such that a catastrophic failure and sudden release of water could adversely threaten downstream life and property. However, the same dam also could be at low risk for failure because it is conservatively engineered, receives regular inspections, and is exceptionally well maintained. Thus, its probability for failure is very low. In other words, risk is the product of hazard multiplied by the probability that a failure will occur. Risk Ratings Hazard Classifi cations 7 Another example to illustrate this concept would be a smaller sized irrigation reservoir located miles from human habitation. In this situation, the dam is rated a low hazard structure because of its location, but it could be at high risk for failure because it was not properly designed by an engineer, it has never been inspected, and it is poorly maintained. It is important to realize that a dam’s hazard rating does not define the physical condition of the structure. Instead, “Hazard” is the definition that is used to estimate the amount of damage that could occur in the event the dam were to suddenly fail and release the contents of its reservoir. For that reason, any dam that is rated a high hazard structure must be properly designed, regularly inspected, and maintained in the best condition at all times because the consequences of a failure are just too great to ignore. All reasonable methods must be implemented to reduce the risk of failure for high hazard dams. Probability of Failure Occurring Hazard Hazard Classifi cations 8 Oregon Dam Safety has divided existing dams into three hazard classifications. Each rating is an estimate of the potential consequences to downstream life and property that would result from a catastrophic dam failure. Low Low hazard dams are scheduled to be inspected every 4 to 5 years depending on the owner’s ability to maintain the dam. A sudden or rapidly developing failure of the dam or a sudden uncontrolled release of stored water from the reservoir would not appear to threaten human life. Downstream property damage would be limited primarily to the stream channel. Signifi cant Significant hazard dams are scheduled to be inspected every 2 to 3 years depending on the condition of the dam, and the owner’s ability to provide upkeep, the maintenance record, or the outward appearance of the dam. A sudden or rapidly developing failure of the dam or a sudden uncontrolled release of stored water would most likely result in significant property damage, and/or the potential for causing the indirect loss of human life. High High hazard dams are scheduled to be inspected on an annual basis, alternating between seasons. A sudden or rapidly developing failure of the dam or a sudden uncontrolled release of stored water would likely result in direct loss of human life. Severe and/or widespread property damage would also be expected to occur. Ratings Hazard Classifi cations 9 Under Oregon law, all water belongs to the public. With few exceptions, any person wishing to appropriate and store surface water or ground water must first obtain a permit from the Water Resources Department. The water right, once developed, is considered to be a type of property right and is attached to the land where it was established. Consequently, real property with an attached water right may be several miles from the actual source of water. In Oregon, landowners with water flowing past, through, or below their property do not automatically have a right to use that water. Oregon’s water laws are based on the Principal of Prior Appropriation. This means the first person to obtain a water right on a stream is the last to be shut off in times of low streamflows. In water-short times, the water right holder with the oldest date of priority can demand the water specified in their water right regardless of the needs of junior users. If there is a surplus beyond the needs of the senior right holder, the water right holder with the next oldest priority date can take as much as necessary to satisfy needs under their right and so on down the line until there is no surplus or until all rights are satisfied. The date of application for a permit to use water usually becomes the priority date of the right. Generally, storage water rights have a junior priority date. For that reason, reservoirs are typically filled during the nonirrigation season from excess winter stream flow. Reservoir applications and other forms can be found on the web: www.wrd.state.or.us Permits Reservoir Permits and the Permitting Process 10 Applying for a Permit to Use Water Oregon law requires a Reservoir Permit from the Water Resources Department to store water in an above-ground reservoir. Additionally, a separate permit is needed to apply the stored water to a beneficial use. In most instances, two applications for permits are usually required for above ground reservoirs, those being: Oregon’s Water Code four fundamental provisions 1. Benefi cial purpose without waste Surface or ground water may be legally diverted for use only if it is used for a beneficial purpose without waste. 2. Priority The water right priority date determines who gets water in a time of shortage. The more senior the water right, the longer water is available in a time of shortage. 3. Appurtenancy Generally, a water right is attached to the land described in the right, as long as the water is used. If the land is sold, the water right goes with the land to the new owner. 4. Must be used Once established, a water right must be used as provided in the right at least once every five years. With some exceptions established in law, after five consecutive years of non-use, the right is considered forfeited and is subject to cancellation. Permits Reservoir Permits and the Permitting Process 11 A primary application for reservoir storage of a given volume of water, including both ground water and stream flow and pumped ground water sources. A secondary application to appropriate surface water or to use water from a reservoir in excess of the amount that was needed to initially fill the reservoir. A secondary application is required to maintain the level of water in the reservoir and to replenish the amount of stored water lost due to evaporation and/or seepage. Obtaining a permit is a critical hurdle in obtaining a water right. A reservoir permit is the authorization necessary from the State of Oregon via the Water Resources Department to store water. With few exceptions, any existing or proposed hydraulic structure for storage of water requires a permit, regardless of its height or capacity. The Alternate Review Application Process for a Water Right Permit pertains to a pond or reservoir of any storage capacity with a dam height less than 10 feet. If the dam is 10 feet or greater, the maximum amount of water stored under the Alternate Review Process must be less than 9.2 acre feet. The Standard Review Application Process is for any reservoir that is both greater than or equal to 9.2 acre feet and with a dam height of 10 feet or greater. With few exceptions, engineered plans and technical specifications must be submitted for review and approval before a Reservoir Permit will be issued for these larger sized structures. • • • • Reservoir Permits and the Permitting Process 12 Preparing the Reservoir Application All entries should be typewritten or neatly printed with dark ink. The appropriate filing fee(s) shall accompany each application at the time of submittal. All items must be completed even though portions of the required information may appear on supplemental maps or drawings. Incomplete applications will be returned to the applicant, and will not be assigned a priority date until they are determined to be complete. How an Application is Processed Once a completed application has been received, the Department must provide public notice of the application within 60 days. The purpose of the public notice is to allow the public the opportunity to submit detailed, legally obtained information to the Department for consideration as to whether or not the application would be injurious to existing water rights. The Department also notifies other state agencies including the Oregon Department of Fish and Wildlife (ODFW). ODFW provides comments as appropriate regarding potential impact to existing fishery resources. All comments must be submitted within 60 days of the public notice. Within the prescribed 60-day period, if the Department does not find injury to existing water rights or is notified about detrimental impacts to existing fishery resources, then the Department may issue a Final Order that will Even if there are no fi sh living in the stream, the Department is required to notify ODFW of all applications. Permits Reservoir Permits and the Permitting Process 13 allow issuance of a permit within 180 days of the priority date. Because of the processing timelines set forth in ORS 537.409, the Department suggests applicants make certain to file an application prior to scheduling excavation work or expending a large amount of money. Nonstatutory (Small) Dams Not Subject to Design Review Nonstatutory dams, those that are less than 10 feet in height or that impound less than 9.2 acre feet, do not require design approval and construction oversight by the Water Resources Department. Nonetheless, a permit to store water is likely required. The local watermaster can assist in filing an application for a permit to store water for these smaller structures. It is recommended that earthen embankment dams less than 10 feet in height or less than 9.2 acre feet storage capacity have a crest width no less than 8 feet, an upstream slope no steeper than 3:1, and a downstream slope no steeper than 2:1. An emergency spillway channel should be constructed around the dam, not over the top of the fill, and lined to prevent erosion. The spillway should be able to withstand the 50-year flood flow without overtopping the dam. It should also direct the passing flow downstream to prevent erosion of the embankment. For best results, all brush, stumps, roots, and organic matter should be cleared from the borrow area and beneath the dam. Only fill materials consisting of non-organic and cohesive soils adjusted in moisture to optimum water content should be used for construction of the dam. Individual layers should not exceed 8 inches in thickness and should be compacted with a sheepsfoot roller or similar equipment. Fill material should be placed in thin layers parallel with the long axis of the dam. Design Requirements for Dams Under Statutory Limits 14 Statutory Sized (Large) Dams The following list is a summary of the minimum requirements for examination and approval of design plans and technical specifications for construction of dams greater than or equal to 10 feet in height and that impound 9.2 acre feet or more of storage. A licensed professional engineer must prepare these design documents and submit them for approval prior to construction. 1. Vicinity Map Location of dam and reservoir in relation to township, range, and quarter-quarter section, together with a survey tie (bearing and distance) from a benchmark on the dam to an established government land corner. Watershed map that delineates the contributing drainage area into the reservoir. Access roads, significant land features, urban areas, or downstream development. Borrow areas, quarries, utilities, and property lines within project boundaries. 2. Plan View of Dam and Appurtenances Topographic contour map, maximum 2-foot interval. Locate by station the primary outlet and auxiliary or emergency spillway; if applicable, include toe drains, filters, log boom, or fish by-pass facilities. Area/Capacity Diagram or stage/storage data tabulating hydraulic depth versus corresponding surface area and reservoir storage capacity. Locations of field exploration or subsurface investigation including bore holes, test pits, excavations, trenches, monitoring wells, and other invasive methods.         15 Design Requirements for Dams Over Statutory Limits 3. Profi le Parallel to Centerline Axis of Dam Existing ground surface and thickness of stripping or grubbing. Grade line for cutoff trench and/or excavation for foundation. Bedrock or foundation material contacts. Crest elevation of dam; include camber if applicable. Locate by station the primary outlet and auxiliary or emergency spillway; if applicable, include toe drains, filters, log boom, or fish by-pass facilities. 4. Sectional View of Dam at Maximum Section Upstream and downstream slopes, including erosion control or armoring. Dam dimensions and elevations; X (width) and Y (height) coordinates. Emergency spillway crest elevation and spillway channel grade line(s). Water surface elevations, including normal pool and flood maximum. Interior material zones and/or internal filters. Invert elevations of outlet conduit, toe drains, and other internal piping. Existing ground surface and thickness of stripping or grubbing. Cutoff trench and/or excavation for foundation, with dimensions.              16 Requirements for Dams Over Statutory Limits 5. Emergency Spillway Detail Drawing Both a sectional and profile view. Elevations and dimensions at all stations where channel configuration or grade lines transition or otherwise change. Dimensions and elevations for stilling basin or other flow and energy dissipaters, including both formed-inplace concrete or constructed channel armoring. Elevations and dimensions of flow control mechanisms such as flash boards, stop logs, lift or tainter gates, or channel splitters. 6. Outlet Conduit and/or Primary Spillway Detail Drawing Cross section showing sizes, dimensions, and type(s) of material, including concrete encasement and/or pipe bedding. Draw down curve, flow rating information, or discharge capacity data. Longitudinal section (profile) illustrating configuration and position of conduit and all joints, flanges, or other connections. 7. Outlet Works Detail Drawing Operating gates or valves, and guard gates or valves; if manufactured, list the name, model number, supplier, etc. Base block or anchor, pedestals, operating stem and/ or lift mechanism. Fish screen, trash rack, or other clog prevention device.           17 Design Requirements for Dams Over Statutory Limits 8. Technical Data All elevations referenced to established benchmark, such as MSL or NGVD. Hydrologic report or calculations verifying adequacy of emergency spillway at 100-year storm (1% flow) or PMF as appropriate. Summary report of foundation investigation which may include site geology, ground water hydrology, drill logs, test pits, laboratory test results and geotechnical stability analysis for rapid drawdown, flood loading and/or seismic analysis as appropriate. Bid package or a complete set of technical specifications for design, manufacture, placement, and testing of construction materials or material components as appropriate. 9. Operation and Maintenance Manual (Signifi cant and High Hazard Dams) Preventative maintenance schedule, contact information, storage/release schedule. 10. Emergency Action Plan (High Hazard Dams) Dam failure/breach analysis for both sunny day and storm scenario. Downstream inundation maps for sunny day and storm failure scenarios. Monitoring and/or warning systems, notification charts, and evacuation procedure(s).         18 Requirements for Dams Over Statutory Limits No person shall construct any dam that is 10 feet or greater in height and stores 9.2 acre feet or more, unless the Department has made an examination of the site and of the plans and specifications and other features involved in the construction of such works, and has approved them in writing. (ORS 540.350; amended 1981) Periodic inspection of existing hydraulic structures for protection of public safety is part of the Oregon Dam Safety Program. However, Oregon laws do not specify the frequency of inspections. The inspections are made under the supervision of the Dam Safety Coordinator. If a person residing on or owning land in the neighborhood of any dam after completion, or in the course of construction, applies to the Director desiring inspection of the works, the Director may order an inspection, or he may make such order on his own motion. If the inspection is deemed justified by the Director, he may require that the owner pay all or part of the expenses for the inspection. (ORS 540.390) If a potential risk is discovered during an inspection or the structure is determined to be unsafe, the owner of the dam is notified and requested to take necessary action to prevent failure of the dam. Owners are expected to maintain their hydraulic structure in a safe and responsible manner and make proper repairs to keep it operational. Many dam owners do not realize their responsibility and liability toward the downstream public and environment. 19 Inspection Process of Inspecting Dams Very Good Condition No apparent problems; new or newly replaced. Well maintained and supervised. No need for increased maintenance or monitoring activities. a. b. c. Acceptable Condition Fully functional and trouble-free operation. Increased maintenance or monitoring may be necessary. Letter to owner may be appropriate to advise of maintenance/monitoring. a. b. c. Unsatisfactory Condition Marginally functional under normal conditions, but could be a potential problem under extreme loading or operating conditions not routinely experienced. Intensive maintenance program necessary to prevent further deterioration. Minor repair, rehabilitation, or restoration may be necessary in addition to increased maintenance or monitoring activities. a. b. c. Repair or Replace Non-functional, defective, or missing component. Deterioration has progressed beyond ability of maintenance program or owner’s willingness to adequately restore to design conditions. Major repair or rehabilitation necessary to restore dam, spillway, or appurtenant works to original design or to standards acceptable to OWRD Dam Safety. a. b. c. 20 Rating Criteria Process of Inspecting Dams Go to www.wrd.state.or.us to fi nd WRD forms. 21 Inspection Form Process of Inspecting Dams 22 Process of Inspecting Dams The Dam Safety Program maintains an inventory of existing hydraulic structures that exceed statutory height and storage criteria. When, during the course of inspection of any of the inventoried dams, a particular structure is discovered to be in violation of safety conditions that would adversely affect or threaten downstream life and property, the Director may act to cause the dam owner to remedy the situation. Upon discovery of a safety hazard that poses a threat to life or property, the Department may notify the owner in writing of the hazard and action(s) necessary to return to the project and appurtenant works to safe design, mechanical operational, or maintenance standards. Failure by the owner to perform the required action may result in proceedings for one or more of the following scenarios: Notice and opportunity for a contested case hearing. [As provided for in ORS 540.350(5).] Cancellation of the permit for failure to make a satisfactory Claim of Beneficial Use. Posting of the structure to prevent storage or to limit operation until the owner has complied with the requested action. Instituting legal action by the District Attorney or Attorney General to have the facility declared a public nuisance. Issuance of an order to prevent storage or to breach the dam. [As provided for in ORS 540.370.] Any other enforcement action permitted by law. 1. 2. 3. 4. 5. 6. Check out ORS 183 and ORS 540 for more information about dam safety enforcement. 23 Enforcement Enforcement Procedures Appendices Go to www.wrd.state.or.us for more information about Oregon water laws. Authority Oregon Revised Statutes pertaining to dams, reservoirs, and dam safety, specifically and generally: ORS 537.190 ORS 537.211 ORS 537.248 ORS 537.400 ORS 537.409 ORS 537.420 ORS 540.340 ORS 540.350 ORS 540.360 ORS 540.370 ORS 540.380 ORS 540.390 ORS 540.400 ORS 541.050 ORS 541.060 ORS 541.510 ORS 541.515 ORS 541.520 ORS 541.525 ORS 541.530 ORS 541.540 ORS 541.545 25 Statutory Natural Ground Surface Spillway Dam Height Structural Height Soil, Rock and Organic Zone Excavated During Construction Longitudinal View Along Centerline Axis 26 Dam Components Dam Foundation Natural Ground Surface Cutoff Trench Height of Dam: Measured at Centerline Axis From Dam Crest to Deepest Point of Natural Channel Cross Section (Typical) 27 Dam Components Left Abutment Downstream Side Lat/Long @ Center of Dam Reservoir Side Outlet Conduit Right Abutment Emergency Spillway Length of Dam Plan (Typical) 28 Dam Plans Measured Dimensions Length of Dam Between Abutments Dam Crest Elevation Dam Crest Width Emergency Spillway Crest Elevation Maximum Dam Height Principle Spillway Inlet Elevation Principle Spillway Outlet Elevation Freeboard Section 29 Dam Plans Crest Width Crest EL. DS Invert Height of Dam Spillway Invert EL. Reservoir US Invert Pipe Water Surface Freeboard Natural Ground Surface Abutment: That part of the valley wall against which a dam is constructed. The left and right abutments of dams are defi ned with the observer viewing the dam looking in the downstream direction, unless otherwise indicated. Acre foot: The volume or amount of water needed to cover 1 acre (43,560 square feet) 1 foot deep (325,851 gallons). Breach: An eroded opening through a dam or spillway that drains the reservoir. A controlled breach is a constructed opening. An uncontrolled breach is an unintentional opening which allows uncontrollable discharge from the reservoir. Channel: A general term for any natural or artifi cial facility for conveying water. Cohesionless Soil: A soil possessing little or no shear strength when unconfi ned (sand). Cohesive Soil: A soil that exhibits considerable shear strength when unconfi ned (clay). Collar: A thin collar placed at uniform intervals along an outlet conduit to retard water seepage. Compaction: Mechanical action to increase the density of a soil by reducing the number or size of internal voids. Conduit: A closed conveyance pipe used to release water through a dam. Contested Case: A legal proceeding before an agency. Core: A zone of low permeability material in an embankment dam. The core is sometimes referred to as central core, rolled clay core, or impervious zone. Cutoff Trench: A trench excavated beneath the dam foundation and backfi lled with impermeable material to retard water seepage under the dam. Dam: An artifi cial barrier across a watercourse or valley for creating a reservoir, diverting water from a channel, or creating hydraulic head. “Any artificial barrier, including appurtenant works, that impounds or diverts the flow of water.” Dam Crest: The top surface of the dam. 30 Glossary Dam Failure: Catastrophic type of failure characterized by the sudden, rapid, and uncontrolled release of impounded water. Dike: An artifi cial protective barrier or obstacle designed to prevent fl ooding of adjacent land surrounded by water. Drain: A pipe or similar feature that collects and directs water to a specifi ed location. Embankment: An engineered earth fi ll. Emergency Action Plan: A formal plan of procedures to alleviate risk during construction of or after completion of a dam, or to reduce the consequences to life and property that would result from a dam failure. Also, a plan of action to be taken to reduce the potential for property damage and loss of life in an area affected by a dam failure or large fl ood. Filter: A material or zone of materials designed to provide drainage without causing movement or erosion of the individual particles comprising the fi lter. Final Order: Final agency action expressed in writing. Flashboard (Stoplogs): Planed timber or steel beams that are physically placed on top of each other in a channel or an outlet so as to adjust the fl ow of water. Flashboards often are an alternative to gates or valves in low-head situations. Flood: A temporary rise in water levels resulting in inundation of areas not normally covered by water. May be expressed in terms of probability of exceedance per year, such as 1 percent chance fl ood, or expressed as a fraction of the probable maximum fl ood or other referenced fl ood of record. Flood Frequency: Refers to the probability (expressed in percentage) that a fl ood will occur in a given year, example 20%, 10% ,or 1%. Flood, Probable Maximum (PMF): The largest fl ood that is estimated for a selected location on a stream resulting from the probable maximum precipitation storm (PMP) in combination with extreme runoff conditions. Flood Surcharge: The storage volume between the top of the active reservoir storage and the design maximum water level. 31 Glossary Foundation: The ground surface upon which a dam is constructed. Freeboard: The vertical distance between the design high-water level in the reservoir and the dam crest. Gate: A movable, watertight barrier for the control of water fl owing through a pipe or channel. (See Valves) Groin: The area along the contact (or intersection) of the face of a dam with the abutments. Hazard Classifi cation: The rating for a dam based on the potential consequences of failure. The rating considers the aggregate damage to downstream life and property that failure of the dam could cause. Height: The maximum vertical distance from natural ground surface to the top of a dam. Hydrograph: A graph showing, for a given point on a stream or conduit, the discharge, stage, velocity, available power, or other properties of water with respect to time. Hydrologic Connection: Condition where water can move between a surface water source and an adjacent sub-surface aquifer. Impervious: Not allowing liquid to pass through; waterproof. Instream Flow: Minimum quantity of water necessary to support the public use requested by an agency. Inundation Map: A map delineating the area that would be fl ooded by a particular fl ood event. It includes the ground surfaces downstream of a dam showing the estimated encroachment by water released because of failure of a dam or from abnormal fl ows released through a dam’s spillway. Invert: Elevation at the bottom of a pipe, conduit, or culvert. Levee: An artifi cial protective barrier built adjacent to a waterway to prevent fl ooding of bordering land. Maximum Water Surface: The highest acceptable water surface elevation with all factors affecting the safety of the structure considered. It is the highest water surface elevation resulting from a computed routing of the infl ow design fl ood through the reservoir under established operating criteria. This surface is also the top of a surcharge capacity. 32 Minimum Streamfl ow: A rate of fl ow established by administrative rule necessary to support aquatic life or minimize pollution. Normal Water Surface: The highest elevation at which water is normally stored, or the design surface elevation which the reservoir is expected to be operated. Order: Agency action expressed orally or in writing directed to a named person or persons; includes any agency decision issued in connection with a contested case hearing. Outlet Works: A device to provide controlled releases from a reservoir. Piping: A characteristic type of erosion of embankment or foundation material (soil) due to leakage. The action of water passing through a soil mass resulting in removal of particles leading to the development of channels or “pipes”. Precipitation, Probable Max (PMP): The greatest amount of precipitation possible resulting from a specifi ed size storm occurring during a distinct period of time at a particular geographic location. Reservoir: A body of water impounded by a dam or other artifi cial construction in which water can be stored. Reservoir Surface Area: Ground surface area covered by water when a reservoir is fi lled to a specifi ed level. Risk: The relationship between the consequences resulting from an adverse event and its probability of occurrence. Seepage: The slow movement or percolation of water through a permeable medium; specifi cally, fl ow through small cracks, voids, or interstices in a dam, abutment, or foundation. Soil: Sediments or other unconsolidated and non-cemented aggregations of particles produced by the chemical/mechanical disintegration of rocks. Spillway: A structure over or through which fl ow is discharged from a reservoir. If the rate of fl ow is controlled by mechanical means such as gates, it is considered a controlled spillway. If the geometry of the spillway is the only control, then it is defi ned as an uncontrolled spillway. 33 Glossary Spillway, Auxiliary: Any secondary spillway that is designed to be operated very infrequently or only in anticipation of extreme climactic events. Spillway, Emergency: A spillway that is designed to provide additional protection against overtopping of dams and is intended for use under extreme conditions such as misoperation or malfunction of the service spillway or other emergency conditions. Spillway, Primary: A spillway that is designed to provide continuous or frequent regulated or unregulated releases from a reservoir without signifi cant damage to either the dam or its appurtenant structures. Storage: The retention of water or delay of runoff either by planned operation, as in a reservoir, or by temporary fi lling of overfl ow areas, as in the progression of fl ood wave through a natural stream channel. Storage, Active (Normal): The volume of the reservoir that is readily available for benefi cial use such as power generation, irrigation, fl ood control, water supply, fi sh culture, and others. Storage, Dead: The volume of water that lies below the invert of the lowest outlet and that cannot readily be withdrawn from the reservoir. Toe of Dam: Those portions of a dam slope that intersect natural ground surface, either upstream or downstream. Top of Dam (Crest): The elevation of the uppermost surface of a dam, usually a road or walkway excluding any parapet wall, railing, etc. Valves: Valves, as distinguished from gates, are constructed so that the closing member remains in the water passageway for all operating positions. Void: Open spaces inside soil, rock or concrete that may be fi lled with air or water or some other gas or liquid. Watermaster: Field representative (1 of 20 statewide) authorized by statute to regulate established water rights according to Oregon’s water laws, based on the principle of prior appropriation. 34 State of Oregon Water Resources Department 725 Summer Street NE, Suite A Salem, Oregon 97301 (503) 986-0900 www.wrd.state.or.us