2 CCR 402-1
Rule 1. Title:
The title of these rules and regulations is “The Rules and Regulations for Dam Safety and Dam Construction.” They may be referred to herein collectively as the “Dam Safety Rules” or “Rules”, and individually as a “Rule.”
Rule 2. Authority:
These Rules are promulgated pursuant to the authority granted the State Engineer in Sections 37-87-102 and 37-87-105, C.R.S.(1973)(1987 Supp.) and Section 37-80-102(11K), C.R.S. (1973), pursuant to section 24-4-103, C.R.S. (1973).
Rule 3. Scope and Purpose:
A. These Rules apply to any dam constructed or used to store water in Colorado. These Rules apply to applications for review and approval of plans for the construction, alteration, modification, repair, enlargement, and removal of dams and reservoirs, quality assurance of construction, acceptance of construction, nonjurisdictional dams, safety inspections, owner responsibilities, emergency preparedness plans, fees, and restriction of recreational facilities within reservoirs. Certain structures defined in Rule 18 are exempt from these rules.
B. The purposes of these Rules are to provide for the safety of dams by establishing reasonable standards and to create a public record for reviewing the performance of a dam. Rule 4. Definitions:
4.A. The following definitions are applicable to these Rules for Dam Safety and Dam Construction: 4.A.(1) “Alteration to, Modification of, or Repair of an Existing Dam or Appurtenant Structure” means to make different from the originally approved construction plans and specifications or current condition, except for ordinary repairs and general maintenance as defined in Rule 12.
4.A.(2) “Appurtenant Structure” means the outlet works and controls, spillways and controls, access structures, bridges, and related housings at a dam. 4.A.(3) “Breach Order” is an order issued by the State Engineer, or his designee, to remove all or part of a dam to the level of the natural ground, so it is incapable of impounding water and creating a hazard.
4.A.(4) “Capacity” is the volume of water capable of being impounded in a reservoir at the high- water line, normally expressed in acre-feet. Dead storage below the natural surface of the ground is excluded.
4.A.(5) “Classification of a Dam” is the placement of a dam into a category based upon an evaluation of the consequences of the failure of the dam absent flooding conditions, assuming the reservoir is at the high-water line. No loss of life nor significant damage is expected to occur if the increased depth of flow is two feet or less and the product of the average flood plain flow velocity and the depth of flow at a critical area is less than seven in the incremental zone.
4.A.(5)(a) A “Class I” dam is a dam for which loss of human life is expected in the event of failure of the dam.
4.A.(5)(b) A “Class II” dam is a dam for which significant damage is expected to occur, but no loss of human life is expected in the event of failure of the dam. Significant damage is defined as damage to structures where people generally live, work, or recreate, or public or private facilities exclusive of unpaved roads and picnic areas. Damage means rendering the structures uninhabitable or inoperable. 4.A.(5)(c) A “Class III” dam is a dam for which loss of human life is not expected, and damage to structures and public facilities as defined for a “Class II” dam is not expected in the event of failure of the dam.
4.A.(5)(d) A Class IV dam is a dam for which no loss of human life is expected, and which damage will occur only to the dam owner's property in the event of failure of the dam.
4.A.(6) A “Dam” is a man-made barrier, together with appurtenant structures, constructed above the natural surface of the ground for the purpose of impounding water. (For Exemptions, See Rule 18.)
4.A.(6)(a) A “Jurisdictional Dam” is a dam which impounds water above the elevation of the natural surface of the ground creating a reservoir with a capacity of more than 100 acre-feet, or creates a reservoir with a surface area in excess of 20 acres at the high-water line, or exceeds 10 feet in height measured vertically from the elevation of the lowest point of the natural surface of the ground where that point occurs along the longitudinal centerline of the dam up to the flowline crest of the emergency spillway of the dam. For reservoirs created by excavation, the vertical height shall be measured from the invert of the outlet. The State Engineer shall have final authority over determination of the vertical height. 4.A.(6)(b) A “Nonjurisdictional Dam” is less than the size and capacity of a jurisdictional dam.
4.A.(6)(c) A “Minor Dam” does not exceed 20 feet in vertical height and 100 acre feet in capacity (see Figure 1).
4.A.(6)(d) A “Small Dam” is greater than 20 feet in vertical height but equal to or less than both 40 feet and 1000 acre-feet in capacity, or is greater than 100 acre feet but equal to or less than both 1,000 acre-feet in capacity and 40 feet in vertical height (see Figure 1).
4.A.(6)(e) An “Intermediate Dam” is greater than 40 feet in vertical height but equal to or less than both 100 feet and 50,000 acre-feet in capacity, or is greater than 1,000 acre feet in capacity but equal to or less than both 50,000 acre feet in capacity and 100 feet in vertical height (see Figure 1).
4.A.(6)(f) A “Large Dam” is greater than 100 feet in vertical height, or greater than 50,000 acre feet in capacity (see Figure 1).
4.A.(6)(g) A “Diversion Dam” is a dam constructed for the purpose of diverting water from the natural stream bed into a canal, tunnel, ditch, or pipeline, and which is not designed or operated for the purpose of impounding significant amounts of water. A dam that both impounds water and diverts water into a canal, tunnel, ditch, or pipeline shall be considered a dam and is subject to these rules. 4.A.(6)(h) A “Flood Control Dam” is a special purpose dam which is normally dry and has an ungated outlet structure which will drain the water impounded during the flood. The jurisdictional size and classification of the dam are determined assuming the reservoir is full to the emergency spillway.
4.A.(7) “Dam Failure Inundation Map” is a map depicting the area downstream from a dam which would reasonably be expected to be flooded in the event of the failure of a dam. 4.A.(8) “Day” as used in these Rules means a calendar day. For computation of time periods as used in these rules, Colorado Rules of Civil Procedure 6(a) shall apply. 4.A.(9) “Emergency Preparedness Plans” are written documents prepared by the dam owner, describing a detailed plan to prevent or lessen the effects of a potential dam failure. 4.A.(10) “Engineer” means a Professional Engineer registered and licensed in Colorado in accordance with Section 12-25-101, C.R.S. (1985).
4.A.(11) “Enlargement to an Existing Dam or Appurtenant Structure” means any alteration, modification, or repair which increases the vertical height of a dam as defined in Rule 4.A.(32).
4.A.(12) “Erosion Control Dam” means a dam constructed for the purpose of controlling erosion, having a vertical height not exceeding 15 feet from the bottom of the channel at the upstream toe of the dam to the crest of the spillway, having a capacity not exceeding 10 acre-feet at the emergency spillway level, and having an ungated out-let works at the two acre-foot level or lower. The water course upon which the dam is located is normally dry. 4.A.(13) “Freeboard” means the vertical dimension from the flow-line crest (or bottom) of the emergency spillway to the low point on the crest of the dam. 4.A.(13a) “Residual Freeboard” means the vertical dimension between the maximum water surface elevation, during the inflow design flood for the reservoir, and the low point on the crest of the dam.
4.A.(14) “Flowline Crest” means the highest elevation of the floor of a spillway at which uncontrolled flow begins.
4.A.(15) “High Water Line” is the water surface elevation of the reservoir at the flowline crest of the emergency spillway or, if no spillway exists, at the crest of the dam. 4.A.(15a) The “Normal High Water Line” is the elevation of the flowline crest of the principal spillway or, if no principal spillway exists, the flowline crest of the emergency spillway.
4.A.(16) “Impound Water” means to store or accumulate water for immediate or future use in a reservoir.
4.A.(17) “Inflow Design Flood” means the flood hydrograph which is used to determine a spillway's hydraulic capacity as required by these regulations. (See Safety Evaluation Flood, Rule 4.A.(27)).
4.A.(18) “Livestock Water Tank Dam” means a dam constructed for the purpose of watering livestock, having a capacity not exceeding 10 acre-feet and a vertical height not exceeding 15 feet from the bottom of the channel at the upstream toe of the dam to the bottom of the emergency spillway. The dam may not be used for irrigation purposes and the water course upon which the dam is located must be normally dry. 4.A.(19) “Natural Surface of the Ground” means the undisturbed ground surface before excavation, or the undisturbed bed of the stream or river. 4.A.(20) “One-hundred-year Flood” means a potential flood which has a magnitude (peak discharge) which is expected to be equaled or exceeded on the average once during any one-hundred-year period (recurrence interval) and has a one percent chance of being equaled or exceeded during any year (0.01 exceedance probability). The terms “one- hundred-year flood,” “one percent chance flood,” and “intermediate regional flood” are synonymous.
4.A.(21) “Outlet” means a conduit (usually controlled by gates or valves) which is used to release impounded water from the reservoir.
4.A.(22) “Owner” means any person or entity who owns, controls, operates a dam, or proposes to construct a dam. For liability purposes, the persons actually in control of a dam shall be deemed the owner, unless notice of the true owner and their address has been filed with the State Engiener by January 1, 1985. Changes in ownership shall be filed with the State Engineer immediately.
4.A.(23) “Probable Maximum Precipitation” (PMP) means the theoretically greatest depth of precipitation for a given duration that is physically possible over a drainage basin at any specific time of year.
4.A.(24) “Reservoir” means a body of water impounded by a dam. 4.A.(25) “Restriction Order” means an order issued by the State Engineer to limit the maximum water surface elevation of the reservoir.
4.A.(26) “Routing Capacity” means the capability of a reservoir to attenuate flood inflows, and is calculated as the inflow of a flood minus both the outflow and surcharge storage for an assumed time increment measured in acre feet.
4.A.(27) “Safety Evaluation Flood” means the flood hydrograph which is used to determine an existing dam's spillway hydraulic capacity as required by these regulations. 4.A.(28) “Surcharge Storage” means the volume of water which may be impounded but not retained within a reservoir between the normal high-water line and the crest of the dam. 4.A.(29) “Safety Inspection” means an investigation by an engineer for the purpose of determining the safe storage level for a reservoir, and includes, but is not limited to, the review of previous inspections, reports, and drawings, site inspections of the dam, spillways, outlet facilities, seepage control and measurement systems, and permanent monument or monitoring installations, if any.
4.A.(30) “Safe Storage Level” means the reservoir water surface elevation at which the State Engineer has determined is the amount of water which is safe to impound in the reservoir.
4.A.(31) “Spillway” means an appurtenant structure which conducts overflows from a reservoir. 4.A.(31a) “Principal Spillway” means the primary or first-used spillway during runoff. It is designed to pass normal flows, and is not normally capable of passing the “Inflow Design Flood” by itself. It is usually an open channel, pipe, or culvert. 4.A.(31b) “Emergency Spillway” means the spillway designed to pass the “Inflow Design Flood” using the routing capacity of the reservoir. Pipe or culvert spillways are not considered to be emergency spillways for determination of vertical height unless accepted by the State Engineer.
4.A.(32) “Vertical Height” means the dimension as measured from the elevation of the lowest point of the natural surface of the ground, or from the invert of the outlet pipe if excavated into the natural ground, whichever is lower, where that point occurs along the longitudinal centerline of the dam, up to the flowline crest of the emergency spillway. For existing dams, the vertical height shall be measured by determining the slope of the foundation and height of the dam at the downstream toe and extrapolating the height of the dam to the longitudinal centerline of the dam. The formula for determining the vertical height of existing dams is: h = h - f - sl; where h = vertical height, h = height of dam from d b d downstream toe, f = freeboard, s = slope of the natural surface of the ground, and 1 = b horizontal distance from the downstream toe to the longitudinal centerline of the dam. The State Engineer shall have final authority over determination of the vertical height (see Figure 2).
FIGURE 2. DAM MEASUREMENTS AT THE MAXIMUM CROSS SECTION (VERTICAL HEIGHT) 402_1_2'VERTICAL HEIGH.jpg Rule 5. Requirements for Construction, or Enlargement, of Jurisdictional Dams or Reservoirs: Rule 5.A. An owner proposing to construct or enlarge a jurisdictional dam or reservoir shall submit an application package, in a form acceptable to the State Engineer, and receive approval of the construction plans and specifications from the State Engineer prior to commencing construction. The application package shall be prepared by an engineer, and shall consist of the following:
1. Application Form 2. Construction Plans 3. Construction Specifications 4. Classification Report 5. Hydrology Report 6. Geotechnical Report 7. Design Report 8. Instrumentation Plan 9. Cost Estimate 10. Filing Fee The requirements for each of these items are as follows: 5.A.(1) A completed application form provided by the State Engineer. This form will be the only information normally available to the public before the project is approved for construction.
5.A.(2) Construction drawings or plans which shall meet the following requirements: 5.A.(2)(a) The plans shall show the design of the dam and each appurtenant structure in sufficient detail so that the contractor or builder is able to construct the proposed structure from the plans and the specifications (see 5.A.[3][a]). 5.A.(2)(b) The first sheet shall include, as a minimum, the name of the dam; the county; Water Division and former Water District in which the dam is located; a list of the drawings that follow the cover sheet; the design engineer's seal (crimp type not acceptable) and signature; the State Engineer's statement and engineer's AS- CONSTRUCTED statement located in the lower right quadrant of the drawing both in the form as follows:
_________________________ State Engineer By:_________________________ Deputy and, These plans represent the AS-CONSTRUCTED conditions of _________________________ dam to the best of our knowledge and judgement, based in part on information furnished by others as of the _________________________ day of _________________________, 19_________________________. _________________________ _________________________ (Engineer's printed name) (Signature)
5.A.(2)(c) Drawings filed with the State Engineer shall be originals, or a high quality reproducible archival copy of the original, and shall be prepared in an appropriate scale so details are legible, drawn with permanent ink on high quality Mylar or equivalent, submitted in an overall size of 24 inches high and 36 inches wide. 5.A.(2)(d) Drawings shall have a minimum margin of two inches on the left and 1/2 inch on the right, top, and bottom.
5.A.(2)(e) Minimum letter size shall be 1/8 inch or 100 Leroy template or equivalent. 5.A.(2)(f) All drawing sheets shall have bar scales in order to allow scaling of reduced drawings.
5.A.(2)(g) All drawing sheets shall have in the lower right-hand corner a 1/2- by 3-inch space for the State Engineer's file number.
5.A.(2)(h) Each sheet shall have the responsible engineer's seal and signature. 5.A.(2)(i) Each sheet shall be numbered sequentially with the first sheet being sheet number one in conjunction with the total numbered sheets; e.g., 1 of 6. 5.A.(3) Construction Specifications which shall meet the following requirements: 5.A.(3)(a) The front cover of the specifications shall show the title or name of the dam (identical to the title on the plans), the county, Water Division and former Water District, in which the dam is located. The first page behind the front cover shall show the name of the dam (identical to the name on the plans), the county, Water Division and former Water District in which the dam is located, and the engineer's seal and signature, and the State Engineer's approval statement as follows: Approved on the_________________________day of_________________________ 19_________________________. _________________________ State Engineer By:_________________________ Deputy 5.A.(3)(b) The specifications shall be indexed.
5.A.(3)(c) Final specifications shall be bound and submitted on a good grade of white 8 1/2- by 11-inch paper.
5.A.(3)(d) The general conditions shall include statements that the plans and specifications cannot be significantly changed without the prior written approval of the State Engineer in accordance with Rule 9.A.(8).
5.A.(3)(e) The general conditions shall include the provision that construction shall not be considered complete until the state engineer has accepted the construction in writing.
5.A.(3)(f) The specifications shall provide that the owner's engineer will monitor the quality of construction as specified in Rule 9.
5.A.(3)(g) The specifications shall include as a minimum, but are not limited to, the following:
5.A.(4) A classification report which complies with these rules, and sets forth the classification of the proposed dam, or for the proposed enlargement of an existing dam. A report is not required for dams which are declared as Class I; however, a dam failure inundation map will be required for the Emergency Preparedness Plan pursuant to Rule 16.A.(3). The report shall include sufficient calculations or data to establish the reasonableness of the predicted dam failure flood which may include several failure rates and sizes of breach, and an assessment of the impact of a dam failure upon the downstream floodplain. The report shall classify the dam in accordance with Rule 4.A.(5). 5.A.(4)(a) The evaluation of the effects of flood inundation in the report shall extend at least to the location downstream where the classification can be properly identified.
5.A.(4)(b) The report shall be submitted in a form acceptable to the State Engineer and shall include but not be limited to:
5.A.(5)(a) The hydrology report shall be submitted in a form acceptable to the State Engineer and shall include but not be limited to the following information:
5.A.(5)(b) The inflow design flood (IDF) requirements for determining the spillway capacity are summarized in the following table. These requirements may be waived for good cause shown. Spillways designed in accordance with these rules will not be required to be enlarged due to subsequent revisions to the probable maximum precipitation estimates, unless, in the opinion of the State Engineer, there is a substantial threat to public safety.
5.A.(5)(b)(III) New Large Class II dams and enlargements shall have spillways capable of passing, as a minimum, the inflow design flood generated by 75 percent of the Probable Maximum Precipitation, unless an incremental damage analysis demonstrates a lesser inflow design flood is applicable.
5.A.(5)(b)(IV) New Intermediate and Small Class II dams and enlargements shall have spillways capable of passing, as a minimum, the inflow design flood generated by 50 percent of the Probable Maximum Precipitation, unless an incremental damage analysis demonstrates a lesser inflow design flood is applicable.
5.A.(5)(b)(V) New Minor, Class II and Large, Intermediate, and Small Class III dams and enlargements shall have spillways capable of passing, as a minimum, the 100-year flood as defined in Rule 5.A.(5)(d). Rule 5.A.(5)(b)(VI) New Minor, Class III dams, and Large and Intermediate Class IV Dams and enlargements shall have spillways capable of passing the 50-year flood as defined by Rule 5.A.(5)(d).
Rule 5.A.5.(b)VII New Small and Minor Class IV dams and enlargements shall have spillways capable of passing the 25-year flood as defined by Rule 5.A.(5)(d).
5.A.(5)(b)(VIII) The minimum size spillway for all Class I, II, and III jurisdictional dams, except minor Class III, for which an incremental damage analysis shows a smaller spillway is justifiable under Rule 5.A.(5)(c), shall be capable of passing the 100-year flood as defined in Rule 5.A.(5)(d). 5.A.(5)(b)(IX) For dams whose spillway cannot pass the inflow design flood requirements defined in parts (I) through (VII) above, the engineer may as an alternative, provide documentation that overtopping of the dam by floods which exceed the spillway capacity will not cause failure of the dam.
5.A.(5)(b)(X) The minimum freeboard requirements for new or enlarged dams shall be based upon the maximum height which will prevent overtopping by wave action, or the sum of the inflow design flood maximum water surface level plus one foot of residual freeboard, or a minimum of five feet unless the State Engineer approves a lesser standard for good cause shown.
5.A.(5)(c) The Incremental Damage Analysis (IDA) used to justify an Inflow Design Flood
5.A.(5)(c)(I) For comparison of the two types of floods, no additional loss of life nor “significant” damage is expected in the incremental zone if the incremental increased depth of flow is two feet or less and the product of the average floodplain flow velocity (in feet per second) and the incremental depth of flood (in feet) is less than seven. 5.A.(5)(c)(II) Documentation for the IDA shall include but not be limited to: a dam break flood plotted on topographic maps of the affected areas; hydraulically appropriate cross-sections of the downstream channel showing flood stages with velocities and discharges for the two floods; incremental damage and loss of life determinations; and a summary of all hydraulic parameters. Documentation shall also include, if deemed necessary by the State Engineer, channel profiles with the various flood stages; aerial photographs of the affected areas; and computer printouts showing flood discharges. stage, and velocities with respect to time. 5.A.(5)(d) The Inflow Design Flood (IDF) shall range between the Probable Maximum Flood and the 25-year flood, with the Inflow Design Flood determined by the following methods:
5.A.(5)(d)(I) When the 100-year flood event is the appropriate Inflow Design Flood, the probable future flow shall be determined by one of the following methods:
5.A.(5)(d)(I)(C) When using the gaging station records as described above, calculations shall be based on procedures outlined in the “United States Water Resources Council, “Guidelines for Determining Flood Flow Frequencies,” Bulletin #17B of the Hydrology Subcommittee, Revised Edition, Interagency Advisory Committee on Water Data, U.S. Department of the Interior, Geological Survey, Office of Water Data Coordination, Reston, Virginia, 22092, March 1982, which is hereby incorporated by reference into this rule, and does not include later amendments to, or editions of, the incorporated material, or other methods as approved by the State Engineer.
5.A.(5)(d)(I)(D) Historical precipitation data of the National Weather Service may be used for determining probable future water flows, provided applicable stochastic procedures outlined in the National Weather Service NOAA Atlas #2 “Precipitation- Frequency Atlas of the Western United States” Volume III- Colorado, U.S. Department of Commerce, NOAA, National Weather Service, Silver Springs, Maryland, 1973, which is hereby incorporated by reference into this Rule and does not include later amendments to our editions of the incorporated material; or other methods approved by the State Engineer, are used to determine the 100-year precipitation. When using precipitation data for determining probable future water flows, the analysis shall consider whether such precipitation occurred as rain or snow, and the magnitude, duration and frequency of precipitation.
5.A.(5)(d)(I)(E) The National Weather Service, NOAA, Atlas #2 “Precipitation-Frequency Atlas of the Western United States” Volume III-Colorado, U.S. Department of Commerce, NOAA, National Weather Service, Silver Springs, Maryland, 1973, is hereby incorporated by reference into this rule, and does not include later amendments to, or editions of, the incorporated material, 1973, or other documents approved by the State Engineer, may be used for determining the 100-year precipitation for calculating the 100-year flood.
Rule 5.A.(5)(d)(I)(F) Whenever a determination of the 50-year or 25-year flood is appropriate, the same principles of Rule 5.A.(5)(d) apply. 5.A.(5)(d)(II) Whenever a determination of probable future surface water flows, or the probability of frequency of their recurrence, at any place in Colorado is required by relation to a longer period than that for which there is a reliable record of flows as defined in (I) above (e.g., flows resulting from Probable Maximum Precipitation), the determination shall be made by interpolation and correlation of known records to the longer period by relating known records of water basins as similar as reasonably possible to the place of determination or basin under consideration, or by use of geologic determinations, or determining Probable Maximum Precipitation by use of other methods reasonably calculated to formulate an accurate estimate of probable future flows or the probability of frequency of their recurrence at the place of determination of such flows. The following methods or other methods approved by the State Engineer, are acceptable:
5.A.(5)(d)(II)(A) Site specific hydrometeorologic analysis, following procedures used by the National Weather Service, to transpose large historical storms to the drainage basin under consideration to determine the Probable Maximum Precipitation. Snowmelt conditions shall be considered as base flow when appropriate. 5.A.(5)(d)(II)(B) The most current Probable Maximum Precipitation estimates developed by the Office of Hydrology, National Weather Service, NOAA Hydrometeorological Report Series may be used for determining probable future flows. Snowmelt conditions shall be considered as base flow when appropriate. 5.A.(6) A geotechnical report which complies with these rules, and evaluates the stability of the foundation, dam, and the slopes of the reservoir rim, and demonstrates that sufficient material is available to construct the dam as designed. The Geotechnical report shall include, but not be limited to, the following:
5.A.(6)(a) For all classes of dams include information on the geology of the local area and dam foundation. Additionally, for Class I dams and large and intermediate size Class II dams include data on faults and the fault history which may affect the dam, the seismicity of the area and region, and a seismic evaluation of the reservoir perimeter slide potential.
5.A.(6)(b) For Class I and Class II dams foundation investigations shall include drilling to and penetration into bedrock or 1.5 times the height of the dam, whichever is less; development of drilling logs; conducting standard penetration tests; making field soils classifications; determination of the water level in each drill hole; in situ permeability; gradation tests of foundation materials especially in the area of drains; and if applicable, determination of whether liquefaction potential is present and whether clayey materials exhibit residual strength properties. 5.A.(6)(c) For Class I and Class II dams, the report shall demonstrate that adequate borrow materials are available for construction. As a minimum, the following qualitative tests shall be included:
5.A.(6)(d) For Class III dams, other than minor ones, the report shall include the field soils classification, geotechnical logs, standard penetration tests and the requirements of Rule 5.A.(6)(c) Sections (1), (2) and (6). The foundation exploration shall include drilling to, and penetration of the bedrock, or 1.5 times the height of the dam, whichever is less.
5.A.(6)(d)I Minor, Class III and all Class IV dams shall include field soils classifications as a minimum.
5.A.(6)(e) For all dams except minor Class III and all Class IV with a spillway located on an earth foundation, the report shall include the following:
5.A.(6)(f) For all dams except minor Class III and all Class IV with spillways located on a rock foundation, the report shall include a geologic description of the rock, including bedding and jointing and demonstrate THAT the site is adequate to accommodate the proposed spillway.
5.A.(6)(g) The following criteria shall be required, as a minimum in the geotechnical design:
5.A.(6)(i) For earth dams, the minimum static stability factor of safety (FS) under steady state conditions is 1.5, the minimum FS for rapid drawdown is 1.2, and the minimum FS for dams requiring residual soil strength analysis shall be determined by the State Engineer.
5.A.(6)(j) For earth dams the seismic stability criteria shall be as follows: 5.A.(6)(j)(I) All Class I dams and Large and Intermediate size Class II dams shall be designed to at least withstand the predicted earthquake loads, based upon an analysis of the potentially active faults, unless sufficient investigations indicate the faults are not active. Accelerations shall be determined by methods acceptable to the State Engineer. 5.A.(6)(j)(II) For all Class I dams, and Large and intermediate size Class II dams, the minimum seismic stability analysis required shall be a pseudo-static analysis which utilizes an appropriate pseudo-static load coefficient as defined in rule 5.A.(6)(j)(V) of not less than 0.05.
5.A.(6)(j)(IV) For all Class I dams, and Large and Intermediate size Class II dams, pseudo-static analysis shall be acceptable if all or the following conditions are satisfied:
5.A.(6)(j)(V) The minimum acceptable pseudo-static stability analysis factor of safety is 1.0, and shall be attainable using a pseudo-static load coefficient of one-half the predicted peak bedrock acceleration (g's), but not less than 0.05.
5.A.(6)(j)(VI) For those Class I dams, and Large and Intermediate Class II dams, for which a pseudo-static analysis is not appropriate, as determined by Rule 5.A.(6)(j)(IV), a deformational analysis shall be performed in a manner acceptable to the State Engineer. The freeboard remaining due to deformation of the dam shall not be less than three feet. 5.A.(7) A design report which complies with these Rules and shall include information to evaluate the design of the dam and appurtenances including references and page numbers to support any assumptions used in the design. The design report should contain information to show that the following have been met:
5.A.(7)(a) Filter design for all chimney drains, filter blankets, and toe drains must be acceptable to the State Engineer. The use of geotextiles as a filter material is not allowed where the drains are not easily accessible for repair or where excavation of the drain can create an unsafe condition at the dam. 5.A.(7)(b) Underdrains and collection pipes shall be constructed using noncorrodible materials.
5.A.(7)(c) Rock riprap shall be well graded, durable and sized to withstand wave action, or channel velocities, and shall be placed on a well-graded pervious sand and gravel bedding or geotextile. Soil cement, designed and constructed in accordance with the principles defined in the “Design of Small Dams”, United States Department of the Interior, Bureau of Reclamation, SEcond Edition, 1973, 1977 revised reprint, U.S. Government Printing Office, Washington, D.C., 20402, which is hereby incorporated by reference into this rule, and does not include later amendments to, or editions of, the incorporated material, may be used in lieu of rock riprap.
5.A.(7)(d) All outlet systems shall be designed and installed in a manner acceptable to the State Engineer and meet the following criteria:
5.A.(7)(d)(II) All principal outlets connected to a pipeline shall have a by-pass valve which will meet the capacity criteria as defined in Rule 5.A.(7)(d)(I) above.
5.A.(7)(d)(III) Outlets for all dams, except for dams with ungated outlets, shall have an operating or guard gate installed at the upstream end of the conduit. Installations where the gates are located within the dam may not require guard gates if it is determined that the safety inspection of the dam will not require inspection of the outlet upstream from the gate, in accordance with criteria set forth in “ACER Technical Memorandum No. 6” USDI, Bureau of Reclamation, Denver, Colorado, November 1985, which is hereby incorporated by reference into this rule, and does not include later amendments to, or editions of, the incorporated material. 5.A.(7)(d)(IV) Outlets shall have trash racks unless exempted by the State Engineer for good cause shown.
5.A.(7)(d)(V) The design report shall include an outlet discharge table (in cubic feet per second) showing the discharge for 10 feet of head, and the discharge for each foot between an elevation five feet below the spillway crest and the crest of the dam. The equation(s) used for determining the discharge shall also be included.
5.A.(7)(e) All spillways shall be designed and installed in A manner acceptable to the State Engineer and meet the following criteria:
5.A.(7)(e)(II) Log booms shall be installed in the spillway approach where logs and other debris may block spillway flow or damage the spillway structure.
5.A.(7)(e)(III) Emergency pipe spillways shall be designed and installed in a manner acceptable to the State Engineer.
5.a.(7)(e)(IV) For flood water detention dams, the principal spillway and outlet shall be able to pass all flood waters at a discharge rate as specified by the pertinent Division Engineer.
5.A.(7)(f) Dam site and reservoir area requirements are as follows: 5.A.(7)(f)(I) The design of a new reservoir or enlargement of an existing dam shall not result in the inundation of properties (except marina-type structures) during the Inflow Design Flood (IDF) unless the owner owns or obtains flood right-of-ways for all areas which may be inundated by the reservoir surcharge capacity. The owner shall submit a written statement certifying he is owner of the properties, or owns the right-of-way on all affected properties, or possesses a right-of-way easement for the reservoir inundation zone.
5.A.(7)(f)(III) Borrow areas shall not be located closer than 200 feet of either toe of the dam unless waived by the State Engineer for good cause shown. 5.A.(7)(f)(IV) The dam crest and appurtenant structures shall be accessible by equipment and vehicles for emergency operations and maintenance. 5.A.(7)(g) Concrete dams shall be designed in accordance with principles provided in U.S. Bureau of Reclamation publications “Design of Gravity Dams”, 1976, and “Design of Arch Dams”, 1977. Roller compacted concrete may be used in concrete construction in accordance with the state-of-the-art. The State Engineer may require additional analysis when the above cited references are inapplicable.
5.A.(8) An instrumentation plan which shall meet the following requirements: 5.A.(8)(a) Gage rods shall be installed in the proximity to the outlet on all dams. The zero mark of the gage shall be placed at the invert elevation of the entrance to the outlet. The gage shall be clearly marked in feet and tenths of feet, and extend to within one foot of the crest of the dam. If the Division Engineer so requires, the gage shall be marked in hundredths of a foot. The elevation of the reservoir may be measured by installing “gages” in the “wet well” of an outlet, but they shall be calibrated to the invert of the entrance to the outlet. 5.A.(8)(b) Class I and Class II dams shall have the following instrumentation: 5.A.(8)(b)(I) Gage rods as described in Rule 5.A.(8)(a) above; 5.A.(8)(b)(II) Monuments, which allow measurement of the horizontal and vertical movements of the dam, that are installed in a manner acceptable to the State Engineer;
5.A.(8)(b)(IV) Station markers at least every 100 feet along the crest of the dam; and 5.A.(8)(b)(V) Piezometers to allow monitoring of the phreatic surface within the dam installed in accordance with industry standards and in a manner acceptable to the State Engineer.
5.A.(8)(c) Class III dams shall have the following instrumentation: 5.A.(8)(c)(I) Gage rods as described in Rule 5.A.(8)(a) above; and 5.A.(8)(c)(II) Seepage weirs or flumes to allow monitoring of leakage through the embankment or foundation.
5.A.(8((d) Class IV dams will not require instrumentation. 5.A.(9) A detailed cost estimate of the construction of the dam including the engineering fees. The cost estimate will remain confidential until after the construction contract is executed. 5.A.(10) A filing fee of $2.00 per $1,000 (or fraction thereof) of the cost estimate, limited to a maximum of $200.00. (See Rule 17.)
Rule 6. Requirements for Alteration, Moficatation, or Repair of an Existing Dam Which will Affect the Safety of the Structure.
Rule 6.A. An owner proposing to alter, modify, or repair a dam shall submit an application package in a form acceptable to the State Engineer and receive approval of the construction plans and specifications from the State Engineer prior to construction. The provisions of Rule 6 shall apply to such application only to the extent they directly relate to the activity for which approval is being sought.
6.A.(1) The requirements of Rule 5.A.(1), 5.A.(2), 5.A.(3), 5.A.(9), and 5.A.(10) shall apply except as modified by Rules 6.A.(2) and 6.A.(3). The requirements of Rules 5.A.(5) (Hydrology Report), 5.A.(6) (Geotechnical Report), 5.A.(7) (Design Report), 5.A.(8) (Instrumentation) apply only where they are needed to support the application. 6.A.(2) Plans for the repair of a dam, or alteration of Class I or Class II dams to nonjurisdictional size may be approved by the State Engineer by letter in lieu of the formal plans procedure per Rule 5.A.(2) and 5.A.(3) subject to the following conditions: 6.A.(2)(a) A completed application form provided by the State Engineer shall be submitted, accompanied by a plan for the repair or alteration and the appropriate specifications, which were prepared by an engineer. The provisions of Rules 5.A.(9), 5.A.(10) (cost estimate and fees) and Rule 11.B. (nonjurisdictional dams) shall apply.
6.A.(2)(b) The plans and specifications shall contain sufficient detail to enable a contractor to bid on, and construct the repair, or alter the dam. The provisions of Rule 9 (construction quality control), except for the time limits of Rules 9.A.(1). 9.B.(1), and 9.C.(1), and Rule 10 (acceptance of construction) shall apply. The engineer shall give as much notice of the start of construction as possible; and 6.A.(2)(c) Upon completion of a repair, the engineer shall file AS-CONSTRUCTED plans that are in conformsance with Rules 5.A.(2) and 5.A.(3). (See Rule 11.B.) 6.A.(2)(d) AS-CONSTRUCTED plans are not required for alterations to nonjurisdictional size.
6.A.(3) Plans for the repair of a small or minor size Class III dam, or any Class IV dam; and plans for the alteration of any Class III or Class IV dam to nonjurisdictional size are exempt from the provisions of Rules 5A, 6, 9 AND 10 except as specified in Rule 6.A.(3)(a). 6.A.(3)(a) The dam owner must provide at least thirty days advanced written notice to the State Engineer. The written notice must contain the name of the dam, the location of the dam, the name of the owner, and a clear description of the work to be performed. If the State Engineer determines that plans and specifications prepared by an engineer are necessary for the repair, the owner will be notified within five working days of the receipt of the notice. The owner cannot begin construction until the plans and specifications are approved by the State Engineer. If plans and specifications are not required. the State Engineer will inform the dam owner of engineering and construction requirements, if any, and will perform construction inspections as he deems necessary. The dam owner must keep the State Engineer informed of the project status, and provide the State Engineer with “AS-CONSTRUCTED” drawings and specifications within sixty days following completion of the work. The “AS-CONSTRUCTED” drawings must be drawn on good quality paper with permanent ink (or equivalent), such that the drawings are reproducible, and suitable as a long lasting permanent record 6.A(4) The inflow design flood (IDF) requirements for existing dams shall be determined in accordance with the principles of Rule 5.A.(5)(c) and (d), except those structures whose spillways were designed and approved in accordance with the methods published in the U.S. Department of the Interior, Bureau of Reclamation, “Design of Small Dams”, Second Edition, 1973, shall be considered adequate for the classification (formerly referred to as hazard rating) for which they were designed. If the classification has changed, then the provisions of Rules 5.A.(5)(c) and (d) apply.
6.A.(4)(a) Whenever the methods of Rule 5.A.(5)(c) and (d) apply, the requirements for determining the spillway capacity are summarized in the following table. These requirements may be waived for good cause shown. Spillways designed in accordance with these rules will not be required to enlarge them due to subsequent revisions in PMP estimates, unless, in the opinion of the State Engineer, there is a substantial threat to public safety. INFLOW DESIGN FLOOD REQUIREMENTS Dam Class I II III Dam Size Large .75 PMP .50 PMP 100 YR Intermediate .75 PMP .50 PMP 100 YR Small .75 PMP .50 PMP 100 YR Minor .50 PMP 100 YR 50 YR 6.A.(4)(a)(I) Existing Large, Intermediate, and Small Class I dams shall have spillways capable of passing, as a minimum, the IDF generated by 75 percent of the probable maximum precipitation, unless an incremental damage analysis demonstrates a lesser flood is applicable. 6.A.(4)(a)(II) Existing, Minor Class I dams, and Large, Intermediate, and Small Class II dams shall have spillways capable of passing as a minimum, the IDF generated by 50 percent of the probable maximum precipitation, unless an incremental damage analysis demonstrates a lesser flood is applicable.
6.A.(4)(a)(IV) Existing Minor Class III, and Large and Intermediate Class IV dams shall have spillways capable of passing the 50-year IDF as defined in Rule 5.A.(5)(d).
6.A.(4)(a)(V) Existing Small and Minor Class IV dams shall have spillways capable of passing the 25-year IDF as defined by Rule 5.A.(5)(d). 6.A.(4)(a)(VI) The minimum size spillway for all existing Class I dams and Large, Intermediate, and Small Class II dams, for which an incremental damage analysis shows a smaller spill-way is justifiable under Rule 5.A.(5)(c), is the 100-year flood as defined by Rule 5.A.(5)(d).
6.A.(4)(a)(VII) For dams whose spillway cannot pass the IDF as defined above, the engineer may, as an alternative, provide documentation that overtopping by floods which exceed the spillway capacity, will not cuase failure of the dam.
6.A.(4)(b) The minimum freeboard requirements for an existing dam shall be based upon the maximum depth determined to either prevent overtopping by wave action, or which will pass the IDF, or a minimum of three feet, unless the State Engineer approves less for good cause shown.
Rule 7. Requirements for Removing or Breaching an Existing Dam Rule 7.A. An owner proposing to Remove or Breach a dam shall submit an application package in a form acceptable to the State Engineer prior to commencing work. Plans for Removal or Breach of a dam shall meet the following requirements:
7.A.(1) A completed application form provided by the State Engineer. 7.A.(2) For Class I and Class II dams, A breach plan prepared by an engineer. 7.A.(2)(a) The dam shall be excavated down to the level of the natural ground, or as necessary in accordance with Rule 7.A.(2)(c), at the maximum section; and the breach shall be of sufficient width to pass the 100-year 24-hour flood at a depth of less than five feet. However, the maximum breach width shall be the total removal of the dam regardless of the flood magnitude;
7.A.(2)(b) The sides of the breach shall be excavated to a slope which is stable but not steeper than one horizontal to one vertical;
7.A.(2)(c) The breach shall be designed to control silt, which has previously been deposited on the reservoir bottom and the excavated material from the breach from washing downstream;
7.A.(2)(d) The reservoir shall be emptied in a controlled manner which will not endanger lives or damage downstream properties; and 7.A.(2)(e) The drawing(s) of the plan for the breach of a dam shall include the location, dimensions and lowest elevation of the breach.
7.A.(3) For Class III and Class IV dams the owner shall submit a written notice of intent to breach the dam to the State Engineer.
7.A.(3)(a) The State Engineer shall determine the size of the breach in accordance with the following: The bottom width of the breach shall be one-half the height of the dam but not less than ten feet; and the side slopes not steeper than one horizontal to one vertical. The breach shall be to original ground at the low point in the foundation of the dam and the excavated material shall not be placed in the stream channel.
Rule 8. Approval for Construction, Enlargement, Alteration, Modification, or Repair Becomes Void After Five Years.
If construction, alteration, or repair of a reservoir dam is not commenced within five years of approval of the application, the State Engineer's approval shall be void. The owner must resubmit the application and receive approval before commencing construction, and shall meet the requirements of the current rules and regulation.
Rule 9. Construction Quality Control (Jurisdictional Dams): 9.A. For Large, Intermediate, and Small, dams rated Class I, the owner shall provide an engineer experienced in dam design and construction, who shall be responsible for the following: 9.A.(1) Not less than 30 days prior to construction, the engineer must submit to the State Engineer a general plan for construction observation. The construction observation plan shall include:
9.A.(1)(a) The date of the start of construction;
9.A.(1)(b) Names and qualifications of the engineer and staff to be used on the project; 9.A.(1)(c) A construction observation schedule for the engineer and its staff; 9.A.(1)(d) For dams on rock foundations, a schedule for observations of the foundation by a geologist, or engineering geologist;
9.A.(1)(e) A schedule for inspection of the gate installation by the gate manufacturer or its representative unless waived by the State Engineer; 9.A.(1)(f) Identification of the firm that will conduct the construction material tests in the field; and 9.A.(1)(g) A schedule of the construction material tests. 9.A.(2) Within ten working days of receipt, the State Engineer shall provide his written comments and approval, or conditions for approval of the construction observation plan. Construction shall not commence without said approval.
9.A.(3) Subsequent to submitting the construction observation plan, but no later than one week prior to commencement of construction, a meeting shall be held between the engineer, State Engineer and the contractor. The contractor shall develop and thoroughly explain their construction control plan along with any anticipated construction difficulties. During this meeting, the means used to divert and care for the stream during construction will be identified by the contractor; and if reasonable, the plan will be approved by the State Engineer. The name of the contractors and any principals in charge shall be furnished to the State Engineer at the meeting.
9.A.(4) The engineer shall observe the construction of the dam. It is the engineer's responsibility to make frequent periodic visits to observe the progress and quality of the construction to determine whether the construction is proceeding in accordance with the approved plans and specifications. The engineer shall endeavor to prevent defects and deficiencies in the construction of the dam and appurtenant structures, and shall disapprove or reject work failing to conform to the approved plans and specifications. 9.A.(5) The engineer shall maintain a record of construction, which as a minimum, shall include: 9.A.(5)(a) Daily activity and progress reports;
9.A.(5)(b) All test results pertaining to construction; 9.A.(5)(c) Photographs sufficient to provide a record of foundation conditions and various stages of the construction through completion;
9.A.(5)(d) All geologic information obtained; and 9.A.(5)(e) Construction problems and remedies.
9.A.(6) A construction progress report summarizing the contents of 9.A.(5)(a), 9.A.(5)(b), and 9.A.(5)(e) above, must be submitted to the State Engineer every 30 days or more frequently if directed by the State Engineer. A summary report of all the items in Rule 9.A.(5) shall be submitted at the end of cosntruction.
9.A.(7) The engineer shall give the State Engineer at least five days advance notice of initial materials placement on the dam's foundation, in the cutoff trench, and on the outlet foundation (or any appurtenance requested by the State Engineer in advance), to allow observation by the State Engineer.
9.A.(8) When unforeseen site conditions or material availability require that the construction work differ significantly from the approved plans and specifications, a change order, including details, must be provided by the engineer to the State Engineer. No change shall be executed until approved by the State Engineer. Major changes must be submitted in writing with supporting documentation, and approved in writing by the State Engiener. Minor changes may be transmitted verbally by the engineer and approved by the State Engineer verbally.
9.A.(9) The engineer shall give the State Engineer at least 10 days advance written notice of the engineer's final construction inspection.
9.A.(10) The engineer shall notify the State Engineer of the completion of the construction in accordance with Rule 10.
9.B. For Minor, Class I Dams, and Large, Intermediate, and Small dams rated as Class II, the owner shall provide an engineer experienced in dam design and construction, who shall be responsible for the following:
9.B.(1) Not less than 30 days prior to construction or as soon as possible for dams whose construction season is affected by freezing weather, the engineer must notify the State Engineer in writing of the following:
9.B.(1)(a) The date of the start of construction;
9.B.(1)(b) The names and qualifications of the engineer and staff to be used on the project;
9.B.(1)(c) A schedule for construction observation by the engineer, including the foundation of the dam;
9.B.(1)(d) Identification of the firm that will conduct the construction material tests; and 9.B.(1)(e) A schedule of the construction material tests. 9.B.(2) The engineer shall observe the construction of the dam. It is the engineer's responsibility to make periodic visits to observe the progress and quality of the construction in order to determine whether the construction is proceeding in accordance with the approved plans and specifications. The engineer shall endeavor to guard against defects and deficiencies in the construction of the dam, and shall disapprove or reject the work failing to conform to the approved plans and specifications. Photographs of the progress of the construction shall be taken for the record.
9.B.(3) The engineer shall submit periodic reports as requested by the State Engineer and shall compile a record of all tests conducted, a summary of geologic information as related to the foundations, and any problems and remedies, for submittal at the end of construction. 9.B.(4) The engineer shall give the State Engineer at least five days advance notice to allow inspection of the cutoff trench and outlet foundation.
9.B.(5) Change orders shall be submitted in accordance with Rule 9.A.(8). 9.B.(6) The engineer shall give the State Engineer at least 10 days advance written notice of the engineers final construction inspection.
9.B.(7) The engineer shall notify the State Engineer of the completion of the construction in accordance with Rule 10.
9.C. For minor Class II and Large, Intermediate and Small dams rated as Class III, the owner shall provide an engineer experienced in dam design and construction, who shall be responsible for the following:
9.C.(1) Not less than 30 days prior to construction or as soon as possible for dams whose construction season is affected by freezing weather, the engineer shall notify the State Engineer in writing of the date construction will begin, the name of the engineer in charge of the project, and the name of the contractor;
9.C.(2) The engineer shall observe, or provide for the observation by a technician the construction work on the dam, the cutoff trench, and outlet works foundation to see that they are in substantial accordance with the approved plans. The engineer shall endeavor to guard against defects and deficiencies in the construction of the dam, and shall disapprove or reject work failing to conform to the approved plans and specifications; 9.C.(3) Periodic tests shall be taken and inspections made. Periodic progress reports shall be submitted as requested by the State Engineer. The engineer, shall compile a record of all tests conducted, and any problems and remedies, for submittal to the State Engineer at the end of construction;
9.C.(4) Change orders shall be submitted in accordance with Rule 6.A.(8); 9.C.(5) The engineer shall give the State Engineer at least 10 days advance written notice of the project engineers final construction inspection; and 9.C.(6) The engineer shall notify the State Engineer of the completion of construction in accordance with Rule 10.
Rule 9.D. For Minor, Class III dams and all Class IV dams, the owner shall provide an engineer experienced in dam design and construction who shall be responsible for the following: 9.D.(1) Notify the State Engineer of the start of construction; 9.D.(2) The engineer shall provide for the observation of the construction and endeavor to guard against defects and deficiencies in the construction of the dam and shall disapprove or reject work failing to conform to the approved plans and specifications; 9.D.(3) Change orders shall be submitted in accordance with Rule 9.A.(8); 9.D.(4) The engineer shall give the State Engineer at least 10 days advance notice of their final construction inspection; and 9.D.(5) The engineer shall notify the State Engineer of the completion of the construction in accordance with Rule 10.
Rule 10. Acceptance of Construction, Enlargement, Alteration, Modification or Repair (Jurisdictional Dams):
10.A. Construction for which application has been made pursuant to Rule 5 shall not be deemed complete nor shall storage of water be permitted until the State Engineer furnishes to the owner a written statement of acceptance, unless temporary approval of storage is granted by the State Engineer. The acceptance shall specify the vertical height, freeboard, length of the dam, the capacity of the reservoir in acre-feet, and any limitation upon, or requirements for the use of the dam. The State Engineer shall furnish the acceptance or denial within 60 days of receipt of a complete notification of completion.
10.B. The engineer shall provide written notification of completion which shall include the following in order to be deemed complete:
10.B.(1) A written notification that the project is complete and in general conforms with the approved plans, specifications and change orders.
10.B.(2) The As-Constructed Plans which meet the requirements of Rule 5. 10.B.(3) A final construction report containing the following information, if applicable in accordance with the requirements of Rule 6:
10.B.(3)(a) A summary of construction, problems encountered, and solutions implemented to resolve the problems; and, 10.B.(3)(b) A summary of construction material tests and geologic observations; and, 10.B.(3)(c) Photographs of construction if required, from exposure of the foundation to completion of construction; and, 10.B.(4) A record of the location of permanent monuments and instrumentation as well as initial surveys and readings shall be submitted if applicable.
10.B.(5) A schedule for the first filling of the reservoir, specifying fill rates, water level elevations to be held for observation, and a schedule for inspecting and monitoring the dam. No filling schedule is required for minor dams rated Class III and all Class IV dams or if waived by the State Engineer for good cuase shown. The owner, however, shall monitor the dam frequently during the first filling.
10.B.(6) A long-term instrumentation monitoring plan for new dams and enlargements (except for minor Class III and all Class IV dams) which shall include: 10.B.(6)(a) The frequency of monitoring;
10.B.(6)(b) The data recording format;
10.B.(6)(c) A graphical presentation of data; and, 10.B.(6)(d) The parties who will perform the work.
10.B.(7) The engineer shall provide periodic review of the data included in the long-term monitoring plan on at least an annual basis for the first five years, whereupon the monitoring shall continue in accordance with Rule 15.C.(2) and 15.C.(3). The engineer shall submit the data and a written assessment of the dam's performance to the State Engineer annually.
10.B.(8) An Emergency Preparedness Plan which conforms to Rule 16. 10.B.(9) Upon written request by the owner and for good cause shown, the State Engineer may temporarily approve storage of water prior to full compliance with Rule 10B. The written request shall include a schedule for compliance with Rule 10B. Rule 11. Nonjurisdictional Dams: Notification of Intent to Construct, Safety Requirements, and Breach Requirements:
Rule 11.A. Any person intending to construct a nonjurisdictional dam which does not meet the requirements for a Livestock Water Tank or Erosion Control Dam, must submit notice of the intent to construct a dam on forms provided by the State Engineer not less than 10 days prior to construction. (See Section 37-87-125, C.R.S. [1985 Supp.].) The forms shall be submitted to the Division Engineer of the Water Division in which the dam is to be located. Rule 11.A.(1) This rule does not apply to exempt structures as defined under Rule 18 of these regulations.
Rule 11.A.(2) Any owner violating the provisions of this rule shall drain the reservoir and prevent the storage of water in the reservoir upon the order of the Division Engineer; additionally, any dam constructed in violation of the provisions of this rule may be considered an obstruction and is subject to removal pursuant to Section 37-92-502(7), C.R.S. (1973). Rule 11.B. Jurisdictional dams which will be altered to nonjurisdictional size shall meet the following safety requirements:
Rule 11.B.(1) Dams which are rated Class I or Class II before they have been altered shall require that their plans be submitted for approval in accordance with Rule 6. The spillway shall be capable of passing as a minimum a 25-year 24-hour precipitation flood or 25- year snowmelt flood, whichever is greater, with no residual freeboard, and without serious damage to the spillway or dam. Freeboard shall be at least three feet but not greater than required to pass the 25-year flood, and pipe spillways shall be at least 30 inches in diameter if approved by the State Engineer.
Rule 11.B.(2) Dams which are rated Class III before they have been altered shall require that their owner submit written notice of the intent to alter the dam to the State Engineer. The State Engineer will advise the owner of what requirements must be met. Pipe spillways shall be at least 30 inches in diameter if approved by the State Engineer, and capable of passing a 10-year 24-hour precipitation flood or 10-year snowmelt flood, whichever is greater, with no residual freeboard and installed at sufficient depth to make the dam nonjurisdictional.. Freeboard requirements will be determined by the State Engineer. Rule 11.C. Existing nonjurisdictional dams shall meet the following requirements: Rule 11.C.(1) Dams which are Class I or Class II structures, and which are found to be unsafe for storage by the State Engineer, shall have the plans for their repair prepared by an engineer and submitted to the State Engineer for approval before construction. The plans do not need to meet the requirements of Rule 5, but must be of sufficient detail to provide for the quality control of the work. Spillways, freeboard, and pipe spillways shall meet the requirements of Rule 11.B.(1).
Rule 11.C.(2) Dams which are Class III, and are found to be unsafe for storage by the State Engineer, shall be repaired in accordance with the State Engineer's directions. Spillways, freeboard, and pipe spillways shall meet the requirements of Rule 11.B.(2). Rule 11.D. Dams which have been altered to nonjurisdictional size, and existing nonjurisdictional dams which are Class IV, or are found to be nonhazardous by the State Engineer, shall have spillways that will control the level of the reservoir and should be able to pass normal runoff in a manner acceptable to the State Engineer.
Rule 11.E. Owners who intend to breach their nonjurisdictional dams shall submit written notice to the State Engineer. The breach shall have a minimum bottom width of ten feet and at least 1:1 side slopes. The breach shall be to original ground, at the low point in the foundation of the dam. Excavated material shall not be placed in the stream channel. Rule 12. General Maintenance, Ordinary Repairs, and Emergency Actions Which Do Not Require Prior Approval of the State Engineer:
12.A. General maintenance and ordinary repairs which do not require prior approval of the State Engineer for the purpose of this rule shall be those activities which do not impair the safety of the dam. These activities include:
12.A.(1) Removal of brush or tall weeds.
12.A.(2) Cutting of trees and removal of slash from the embankment or spillway. Removal of small stumps is acceptable provided no excavation into the embankment occurs. 12.A.(3) Rodent control or extermination by trapping, poisoning, or shooting. Repair of minor rodent damage is acceptable provided it does not involve excavation into the embankment.
12.A.(4) Repair of erosion gullies on the embankment or in the spillway. Large gullies which have already weakened the dam must be repaired in accordance with Rule 6. 12.A.(5) Surface grading of the embankment crest or spillway to eliminate potholes and provide proper drainage provided that the freeboard is not reduced. 12.A.(6) Placement of additional riprap and bedding on the upstream slope, or in the spillway in areas which have sustained minor damage. This would involve restoring the original riprap protection where the damage has not yet resulted in weakening of the dam. 12.A.(7) Painting, caulking, or lubricating metal structures. 12.A.(8) Patching or caulking spalled or cracked concrete to prevent deterioration. 12.A.(9) Removing debris, rock, or earth from outlet conduits or spillway channels. 12.A.(10) Patching to prevent deterioration within outlet works. 12.A.(11) Replacement of worn or damaged parts of outlet valves or controls to restore them to original or equivalent condition.
12.A.(12) Repair or replacement of fences intended to keep traffic or livestock off the dam or spillway.
12.A.(13) And work of a similar nature and magnitude which does not impair the safety of the dam.
12.B. General maintenance and ordinary repair which may impair safety such as excavation into or near the toe of the dam, construction of new appurtenant structures for the dam, and repair of damage which has already significantly weakened the dam must be done in accordance with Rule 6. When questions arise concerning this rule, the determination of general maintenance and ordinary repair will be made by the State Engineer.
12.C. Emergency actions not impairing the safety of the dam may be taken before guidance can be provided by an engineer, and do not require prior approval of the State Engineer. Emergency actions will usually not serve as a permanent solution to the problem being addressed. Emergency actions may include:
12.C.(1) Stockpiling materials such as riprap, earthfill, sand, sandbags and plastic sheeting. 12.C.(2) Lowering the reservoir level by making releases through the outlet or a gated spillway, by pumping, or by siphoning. Where large releases are to be made, the Division Engineer shall be notified.
12.C.(3) Armoring eroded areas by placing sandbags, riprap, plastic sheeting, or other available material.
12.C.(4) Plugging leakage entrances on the upstream slope. 12.C.(5) Increasing freeboard by placing sandbags or temporary earthfill on the dam. 12.C.(6) Diverting flood waters to prevent them from entering the reservoir basin. 12.C.(7) Constructing training berms to control flood waters. 12.C.(8) Placing sandbag ring dikes around boils at the downstream toe to provide back pressure.
12.C.(9) Removing obstructions from outlet or spillway flow areas. 12.D. Lowering the water level by excavating the spillway or embankment is prohibited unless failure is imminent. The State Engineer shall be notified as soon as reasonably possible of any emergency condition that exists and any emergency action taken.
12.E. For all Class I and Class II dams, the Emergency Preparedness Plan must be implemented in conjunction with any emergency actions taken in accordance with Rule 12.D. Rule 13. Safe Storage Level:
13.A. The State Engineer has the authority to determine the safe storage level for every reservoir in the state. The reservoir owner shall not store water in excess of the amount so determined by the State Engineer to be safe. The owner shall not place flashboards or other devices in the emergency spillway without first filing and receiving approval of an application for modification of the dam in accordance with Rule 6.
13.B. If the dam safety inspection or information from other reliable sources reveals problems affecting the safe storage level of the reservoir, the State Engineer will issue a restriction order. The dam owner shall comply with the restriction order. If the dam owner wishes to store water in his reservoir in excess of the level set in the restriction order, he shall provide for engineering evaluations deemed necessary by the State Engineer and shall complete required repairs. 13.C. When a determination of safe storage level is made by the State Engineer the safety evaluation flood for existing dams will be evaluated in accordance with the standards set forth in Rule 6.A.(4).
13.D. When a determination of safe storage level is made, the State Engineer will periodically review the classification of existing dams by evaluating the consequences of failure and applying the definitions of Rule 4.A.(5). If the State Engineer's review indicates that the consequences of failure have increased or decreased due to changes in development within the dam failure inundation area, the State Engineer will assign an appropriate new classification and will require within a reasonable time, that the dam meet the requirements of these rules as they apply to that classification.
Rule 14. Safety Inspections by Owner's Engineer:
14.A. An owner may provide a safety inspection report to the State Engineer regarding the safe storage level of a reservoir. The State Engineer may utilize the owner's safety inspection report in lieu of a State Engineer safety inspection report if said report is written by a qualified engineer, as defined below. The owner's engineer must notify the State Engineer and submit a written summary of qualifications at least 14 days prior to the scheduled safety inspection. 14.B. An engineer shall be considered qualified to provide information to the State Engineer regarding the safe storage level of a reservoir if the engineer meets the following minimum qualifications: 14.B.(1) Registration as a professional engineer in Colorado; 14.B.(2) Three years of experience in the field of dam safety; and 14.B.(3) Actual experience in conducting safety inspections of dams. 14.C. Dam safety inspections by the owner's engineer shall include, but are not limited to: review of previous inspections, reports and drawings; site inspection of the dam, spillways, outlet facilities, seepage control and measurement system; and permanent monument or monitoring installations, if any. The inspection shall include an assessment of all parts of the dam which are related to the dam's safety. (See Rule 15. for outlet inspection requirements.) The engineer shall prepare an inspection report which describes the findings, and lists actions the dam owner must take to improve the safety of the dam to an acceptable level. The report shall include the engineer's recommendation of the safe storage level.
14.D. If the owner elects to retain an engineer to conduct safety inspections, such inspections shall be conducted annually for all Class I and Class II dams and once every five years for all Class III dams. Class IV dams will not be inspected periodically, but will be if a complaint is received about their safety.
Rule 15. Owner's Responsibilities:
15.A. It is the owner's responsibility to allow or to provide for inspection of outlet facilities on his dam. The frequency of outlet inspections and the requirements of those inspections are as follows: 15.A.(1) Class I and Class II dams shall receive a Type A outlet inspection annually, and Type B inspections not to exceed once every ten years unless the condition indicates more frequent inspections are necessary. A Type B inspection of the entire outlet conduit shall only be required on dams without upstream gates if ordered by the State Engineer in conformity with Rule 15.A.(4). Type B inspections may be waived where the condition of the outlet conduit would not be considered detrimental to the safety of the dam. 15.A.(2) Class III and Class IV dams shall receive a Type A outlet inspection in conjunction with the safety inspection of the dam.
15.A.(3) A Type A outlet inspection shall consist of:
15.A.(3)(a) Observation of exposed surfaces of the inlet and outfall structures, and control valves and vaults; and, 15.A.(3)(b) Testing of the outlet valves for proper operation; and, 15.A.(3)(c) Observation of the downstream end of the conduit and adjacent embankment for leakage; and, 15.A.(3)(d) Observation of the dam (upstream slope, crest, downstream slope or natural ground) in the vicinity of the outlet alignment for signs of distress which would indicate failure of the outlet system.
15.A.(4) A Type B outlet inspection shall consist of a complete Type A inspection, a close inspection of the interior of the conduits, outlet wells, and access ways, and testing of the outlet valve(s) throughout the full operating range. In cases where the conduits are too small for a person to safely enter, the owner shall provide for an inspection using video or other remote sensing equipment capable of detecting flaws or imperfections within the conduit. A written report of inspection findings, including the opinion of the owner's engineer, must be submitted to the State Engineer unless waived by the State Engineer for good cause. A Type B inspection of the normally inundated outlet conduit of a dam without upstream guard gates shall be requried only when existing baseline data available to the State Engineer is inadequate to permit an evaluation of the condition of the outlet conduit. Thereafter, such inspections shall only be required if the criteria set forth in ACER Technical Memorandum No. 6. U.S. Department of the Interior, Bureau of Reclamation, 1985, indicate the need for an inspection. In ordering such inspections, the State Engineer shall coordinate with the dam owner and make all reasonable efforts to prevent expense and waste of water consistent with ensuring dam safety. 15.A.(5) At any time the water level in a dam without upstream gates on the outlet conduit will be lowered to the ivnert of the conduit, or the normally inundated conduit will be otherwise dewatered and available for inspection, the dam owner shall inform the State Engineer in writing and may request the State Engineer to conduct an inspection of the entire outlet conduit for the purposes of this rule. If, upon ten days notice of the opportunity to inspect the outlet conduit, the State Engineer fails to do so, he shall not thereafter require an inspection of the conduit in absence of a finding that an inspection is required made in accordance with ACER Technical Memorandum No. 6.
15.B. The owner is responsible for ensuring frequent observation of his dam, unless prohibited by weather or difficulty of access to the dam, especially at times when the reservoir is full, during heavy rains or flooding, and following an earthquake. When the reservoir water level is greater than half the full storage capacity, Class I and Class II dams shall be observed at least twice a month, and a Class III dam shall be observed at least every three months. The observations shall be conducted in accordance with methods acceptable to the State Engineer. Conditions which threaten the safety of the dam must be reported to the State Engineer in accordance with the Emergency Preparedness Plan for Class I and II dams as soon as reasonably possible, after discovery of the conditions. If dam failure appears imminent, the county sheriff (or emergency official) must be promptly notified. The owner is responsible for the safety of the dam and shall take action to lower the reservoir if it appears that the dam has weakened or is in danger of failing.
15.C. The owner of a dam is responsible for installing, maintaining, and monitoring the required instrumentation:
15.C.(1) The following minimum instrumentation is required on existing dams; however, the State Engineer may require additional instrumentation when he deems it necessary. 15.C.(1)(a) Class I Dams shall have monuments to allow monitoring of horizontal and vertical movement of the embankment, and weirs or flumes to allow monitoring of leakage.
15.C.(1)(b) Class II and Class III Dams shall have weirs or flumes to allow monitoring of leakage.
15.C.(1)(c) All dams shall have gage rods or other acceptable measuring device pursuant to Rule 5.A.(8)(a).
15.C.(2)The dam owner shall monitor weirs during each routine observation of the dam (see Rule 15.B.) owners of Class I dams shall also be responsible for providing second order surveys of horizontal and vertical monuments. These surveys are required annually for five years (including the year of installation of the monuments), and then once every five years thereafter. The State Engineer may also approve other methods for monitoring of movement monuments on the dam and may require monitoring at any frequency deemed necessary based upon review of inspection data and information from other reliable sources.
15.C.(3) The dam owner is responsible for ensuring that all instrumentation data is properly recorded in an acceptable format and sent to the State Engineer annually. The State Engineer may require that instrumentation data for Class I and Class II dams be evaluated by the owner's engineer and the analysis sent to the State Engineer annually, unless more frequent reporting is required by the State Engineer. 15.C.(4) The dam owner shall promptly notify the State Engineer of any abnormal changes in instrumentation data, as compared to historical data and trends. 15.D. The owner is responsible for adequate and timely maintenance of the dam. The owner shall establish an annual maintenance plan to ensure that the maintenance, as identified in Rule 9.A., is accomplished.
15.E. The owner shall ensure that trash racks are installed on all outlet structures unless waived in writing by the State Engineer.
15.F. Any change in ownership of a dam shall be immediately filed with the Office of the State Engineer. Rule 16. Emergency Preparedness Plans (EPP):
16.A. Owners of Class I and Class II dams shall prepare, maintain, and exercise Emergency Preparedness Plans (EPP) for immediate defensive action to prevent failure of the dam. An EPP shall contain as a minimum the following:
16.A.(1) The identification of equipment, manpower, and material available for implementation of the plan;
16.A.(2) A notification procedure for informing the local emergency agencies (e.g., emergency coordinator or county sheriff), and the State Engineer of the problem; 16.A.(3) A dam failure inundation map for Class I dams; 16.A.(4) A topographic map for Class II dams showing the stream which will be flooded; and, 16.A.(5) A procedure for warning nearby local residents if failure of the dam is imminent. 16.B. The owner shall use the State Engineer's model EPP, which is available at no cost, or equivalent, for guidance in preparing the details of the components above. 16.C. The owner shall submit a copy of the proposed EPP to the Colorado Division of Disaster Emergency Services (DODES) and all local emergency coordinators involved in the plan for review. The owner shall incorporate reasonable recommendations from the above, if received within sixty days of the submittal.
16.D. The owner shall review and update the EPP as necessary annually. Rule 17. Fees:
17.A. The owner shall submit with the application for construction, enlargement, alteration, modification, or repair an amount equal to two dollars for each one thousand dollars or fraction thereof of the estimated cost of construction including engineering costs, but the maximum fee shall not exceed $200. When an owner resubmits an application which was previously received and disapproved by the State Engineer, the owner shall submit a new filing fee in accordance with the above. Checks shall be made payable to the Colorado Division of Water Resources. 17.B. Pursuant to Sections 37-87-106 and 111, C.R.S. (1973)(1987 Supp.), the dam owner shall be responsible for payment of invoices from the State Engineer for safety inspections and construction observation. The invoice shall include actual salary, travel, subsistence, and itemized extraordinary expenses at prevailing rates for state officers and employees not to exceed $125 per day per dam or reservoir. The total charge to one owner shall not exceed $125.00 per day. The payment is due within 30 days of receipt of the invoice. Rule 18. Exempt Structures:
18.A. Existing or proposed structures not designed or operated for the purpose of impounding water are exempt from these rules and regulations. Exempt structures include: 18.A.(1) Highways, roadfills, and railroad embankments, (except those designed or modified with the purpose or effect of impounding water for uses other than flood detention); and, 18.A.(2) Diversion dams if less than jurisdictional size and all diversion dams of any size if Class III or IV.
18.A.(3) Refuse embankments; (e.g., solid waste disposal facilities). 18.B. Mill tailing impoundments which are permitted under the Colorado Mined Reclamation Act, Sections 34-32-101 through 125, C.R.S. (1973)(1987 Supp.)(Minerals), or the Colorado Surface Coal Mining Reclamation Act, Sections 34-33-101 through 137, C.R.S. (1973) (1987 Supp.) (Coal) are exempt from these rules and regulations.
18.B.(1) Any solution process impoundment permitted under the Colorado Mined Reclamation Act, or the Colorado Surface Coal Mining Reclamation Act, are exempt from these regulations.
18.C. Uranium mill tailing and liquid impoundment dams, permitted under the Colorado Department of Health are exempt from these rules and regulations. Raw and potable water dams, sewage effluent dams, and water treatment sludge dams associated with the uranium mill are not exempt. 18.D. Siltation structures which are permitted under the Colorado Surface Coal Mining Reclamation Act, Sections 34-33-101 through 137, C.R.S. (1973)(1987 Supp.)(Coal), are exempt from these rules and regulations.
18.E. Structures which store water only below the lowest point of the natural ground are exempt from these rules and regulations unless an outlet works is constructed to develop water. 18.F. Livestock Water Tanks as defined in the Livestock Water Tank Act of Colorado, Sections 35-49-101 through 116, C.R.S. (1973), are exempt from these rules and regulations. 18.G. Erosion Control Dams as defined in Section 37-87-122, C.R.S. (1973), are exempt from these rules and regulations.
Rule 19. Restriction of Recreational Facilities Within Reservoirs: 19.A. No person, including any state or federal agency, quasi-municipal corporation, or political subdivision, shall construct any permanent recreational structure within a reservoir below the elevation of the bottom of the spillway unless:
1. The facility is constructed to withstand partial or complete inundation without significant damage; or 2. The facility is necessary to the operation of the reservoir; and 3. The facility is capable of being restored with a minimum amount of cleaning or expense. Boatramps, docks, and marinas are exempt from these rules. 19.B. This rule does not apply to facilities completed prior to July 1, 1984, but shall apply to any enlargements or modifying of such facilities.
19.C. Any person planning on constructing, enlarging, or modifying any facility coming under this rule shall notify the State Engineer in writing 180 days in advance of construction. They shall include the following information:
1. The name and location of the reservoir and/or dam;
2. Whether the recreational facility is new, or an enlargement or modifying of a facility completed prior to July 1, 1984;
3. A description of the facility, its intended purpose, and its location within the reservoir including depth below the high water line; and 4. A description of how the facility will be able to withstand the damage from the inundation without a significant amount of cleaning or expense to restore it. 19.D. No person shall be allowed to construct, enlarge, or modify any facility coming under this rule until approved by the State Engineer.
Rule 20. Waiver or Delay of Enforcement of Rules by the State Engineer The State Engineer may waive or delay the enforcement of any of the responsibilities of dam owners under the foregoing rules in particular cases if in his judgement dam safety will not be unreasonably impaired and the circumstances of the individual case so warrants. Such circumstances may include, but are not limited to, the benefits which would be realized by full enforcement, the cost or difficulty of complete compliance, the owner's good faith efforts to comply, the expected remaining life of the structure, and the impacts of beneficial use of water in Colorado. Rule 21. Rules of Reference Certified copies of the complete text of the materials incorporated by reference in these rules shall be maintained by the Office of the State Engineer and shall be available for public inspection during regular business hours. Certified copies of the material incorporated shall be provided at cost upon request. The title and address of the branch of the Office of the State Engineer which will provide information regarding how incorporated material may be examined or obtained is: Dam Safety Branch, 1313 Sherman Street, Room 818, Denver, Colorado, 80203.
Rule 22. Severability If any portion of these Rules and Regulations for Dam Safety and Dam Construction is found to be invalid, the remaining portion of the rules shall remain in force. Rule 23. Revision The State Engineer may revise these Rules and Regulations for Dam Safety and Dam Construction in accordance with Section 24-4-103, C.R.S. Such revisions may be the result of new data or technology, or the submittal of a petition by an interested person pursuant to Section 24-4-103(7), C.R.S. and 2 C.C.R. 402-5 1.1.3.B.2.
Rule 24. Statement of Basis and Purpose Incorporated by Reference The Statement of Basis and Purpose for the adoption of Rules and Regulations for Dam Safety and Dam Construction is incorporated by reference as part of these rules. Rule 25. Effective Date