2 CCR 402-1
DEPARTMENT OF NATURAL RESOURCES Office of the State Engineer RULES AND REGULATIONS FOR DAM SAFETY AND DAM CONSTRUCTION 2 CCR 402-1 [Editor’s Notes follow the text of the rules at the end of this CCR Document.] _________________________________________________________________________ TABLE OF CONTENTS Rule 1. Title Rule 2. Authority Rule 3. Scope and Purpose Rule 4. Definitions Rule 5. Determination of Safe Storage Level Rule 6. Design Submittal Requirements Rule 7. Design Requirements Rule 8. Construction Requirements Rule 9. Requirements for Removing or Breaching an Existing Dam Rule 10. Construction, Modification, Alteration, Repair, and Breach of Non-Jurisdictional Size Dams Rule 11. General Maintenance, Ordinary Repairs, and Emergency Actions Rule 12. Safety Inspections Performed by the Owner's Engineer Rule 13. Owner's Responsibilities Rule 14. Exempt Structures Rule 15. Restriction of Recreational Facilities within Reservoirs Rule 16. Waiver or Delay of Enforcement of Rules by the State Engineer Rule 17. Appeal of Requirements or Approval Rule 18. Rules by Reference Rule 19. Severability Rule 20. Revision Rule 21. Statement of Basis and Purpose Incorporated by Reference Rule 22. Effective Date Rule 1. Title 1.1 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 2.1 These Rules are promulgated pursuant to the authority granted the State Engineer in sections 37- 87-102 and 37-87-105, C.R.S.; section 37-80-102 (1)(k), C.R.S.; and section 24-4-103, C.R.S.
2.2 These Rules do not change the meaning of any statute.
Rule 3. Scope and Purpose 3.1 These Rules apply to any jurisdictional or non-jurisdictional dam constructed to impound water in Colorado. Certain structures defined in Rule 14 are exempt from these Rules.
3.2 The purpose of these Rules is to provide for public safety by establishing reasonable standards and to create a public record for reviewing the performance of a dam. Rule 4. Definitions 4.1 Alteration, Modification, Repair, or Enlargement of an Existing Dam and/or Appurtenant Structures. Construction that could affect the safety of the dam.
4.2 Annual Exceedance Probability (AEP). The probability of occurrence in any one year.
4.3 Appurtenant Structure. Component other than the material structure of the dam itself such as the outlet works and controls, spillways and controls, access structures, bridges, and other systems directly related to the safe operation of a dam.
4.4 Breach Order. An order issued by the State Engineer, or the State Engineer’s designee, for removal of all or part of a dam to permanently reduce the maximum storage level, minimize the risk of failure, and/or the potential of damage downstream due to the failure of the dam.
4.5 Capacity. As used in section 37-87-105 (1), C.R.S., the volume of water impounded by a dam at the high water line. Storage below the natural surface of the ground and low-level outlet is generally excluded.
4.6 Dam. A constructed barrier, together with appurtenant structures, constructed above ground surface for the purpose of impounding water. Flood control and storm runoff detention dams are included.
4.6.1 Jurisdictional Size Dam. A dam creating a reservoir with a capacity of more than one hundred (100) acre-feet, or a surface area in excess of twenty (20) acres at the high water line, or where the jurisdictional height exceeds ten (10) feet. Jurisdictional height is defined in Rule 4.7.1.
4.6.2 Non-Jurisdictional Size Dam. A dam creating a reservoir with a capacity of one hundred (100) acre-feet or less, and a surface area of twenty (20) acres or less, and a jurisdictional height of ten (10) feet or less. Non-jurisdictional size dams are regulated and subject to the authority of the State Engineer.
4.6.3 Diversion Dam. A dam constructed for the primary purpose of diverting water from a natural watercourse into a canal, tunnel, ditch, or pipeline.
4.6.4 Flood Control Dam. A dam that is normally dry and has an ungated outlet structure for the controlled release of water impounded during and subsequent to a flood event.
4.7 Dam Height. (See Figure 4.1)
4.7.1 Jurisdictional Height. The vertical dimension measured from the lowest point of the natural surface of the ground or the invert of the outlet pipe, whichever is lower, where the low point occurs along the longitudinal centerline of the dam crest, to the emergency spillway crest.
4.7.2 Hydraulic Height. The vertical dimension measured from the lowest point of the upstream toe of the dam to the emergency spillway crest.
4.7.3 Structural Height. The vertical dimension measured from the lowest point of the excavated foundation to the crest of the dam.
Figure 4.1: Determination of Dam Heights 4.8 Inundation Map. A map depicting the area downstream from a dam that would reasonably be expected to be flooded in the event of a dam failure.
4.9 Emergency Action Plan (EAP). A living document containing a written plan of actions used by an emergency response team to minimize property damage and loss of life in an area affected by a dam failure or large flood.
4.10 Engineer. An Engineer registered and licensed in Colorado in accordance with article 12-120, Part 2, C.R.S. The Engineer will be in “responsible charge,” as defined in section 12-120-202, C.R.S., of the design and of the observation of construction. In general, the Engineer is responsible for the following:
A. Demonstrating a minimum of five years of experience as a registered Engineer in the design, construction, and safety evaluation of the type of dam under review;
B. Understanding all applicable regulatory requirements of the project and the required work, analyses, and oversight needed to complete a safe design and to observe construction to evaluate compliance with plans and specifications of the project;
C. Using current state of the practice methods and means to site and design dams with safety as the primary goal and to complete engineering methodology that represents the professional level of care exercised by qualified engineers; and D. If necessary, assembling and supervising a team of qualified engineers, geologists, geological engineers, and other professionals as required to address all of the disciplines for the design and the observation of construction of a dam.
4.11 Freeboard.
4.11.1 Normal Freeboard. The vertical dimension between a spillway crest and the lowest point on the dam crest.
4.11.2 Residual Freeboard. The vertical dimension between the maximum water surface elevation during a flood event and the lowest point on the dam crest.
4.12 Geologist. An individual possessing specific knowledge of the geological sciences and the principles of engineering analysis and design acquired by professional education or demonstrated experience related to dams, and qualified to apply such knowledge to ensure geologic elements affecting the dam are adequately accounted for in design and construction.
4.13 Hazard Classification. One of four categories defined below as determined by analysis of potential consequences from a sunny day failure of the dam. Conditions for evaluation are absent flooding and the reservoir is assumed to be full to the high water line at the time of failure. The hazard classification establishes all the design criteria for a dam except for spillway size, which is controlled by the Hydrologic Hazard defined in Rule 4.15.
4.13.1 High Hazard. A dam for which life loss is expected to result from failure of the dam.
4.13.2 Significant Hazard. A dam for which significant damage, but no life loss is expected to result from failure of the dam. Significant damage is defined as damage to structures where people generally live, work, or recreate, including public and private facilities. Significant damage is determined to be damage sufficient to render structures or facilities uninhabitable or inoperable.
4.13.3 Low Hazard. A dam for which neither life loss nor significant damage as defined for a Significant Hazard dam are expected to result from failure of the dam.
4.13.4 No Public Hazard (NPH). A dam for which minimal damage, with no life loss, is expected to result from failure of the dam.
4.14 High Water Line. The elevation of the emergency spillway crest. If no emergency spillway exists, the elevation of the dam crest.
4.15 Hydrologic Hazard. Potential consequences downstream of a dam caused by floodwaters released by overtopping failure of the dam. Hydrologic hazard establishes design criteria for spillway size.
4.15.1 Extreme. Life loss potential of 1 or more.
4.15.2 High. Life loss potential of less than 1.
4.15.3 Significant. No life loss potential but significant damage is expected to occur.
4.15.4 Low. No life loss potential or significant damage is expected to occur.
4.16 Incremental Consequences. The difference in impacts that would occur due to failure or misoperation of the dam over those that would have occurred without failure or misoperation of the dam or appurtenances.
4.17 Inflow Design Flood (IDF). The flood hydrograph used to determine if the emergency spillway's hydraulic capacity meets the safety standards as defined in Rule 7.2.
4.18 Natural Surface of the Ground. The undisturbed ground surface before excavation, or the undisturbed bed of a natural watercourse.
4.19 Normal Water Line. The elevation of the service spillway crest. If there is no service spillway, the normal water line and high water line are the same.
4.20 Outlet. A conduit (usually regulated by gates or valves) used for releasing impounded water from the reservoir.
4.21 Owner. The person or persons in control of the physical structure of any dam in accordance with section 37-87-104.5, C.R.S. Person or persons refers to any individual, private or non-profit company, special district, federal, state, or local government agency, or any other entity in direct routine control of a dam and reservoir, and/or directly involved in the physical operation and maintenance of a dam, and/or proposes to construct a dam.
4.22 Plans. All necessary drawings, cross-sections, tables, notes, maps and other information necessary to accompany the construction specifications for design review and approval, and construction of a dam.
4.23 Potential Failure Mode (PFM). A physically plausible process for dam failure resulting from an existing inadequacy or defect related to a natural foundation condition, the design or construction of the dam or appurtenant structures, the materials incorporated, the operations and maintenance, or the aging process, which can lead to an uncontrolled release of the reservoir.
4.24 Potential Failure Modes Analysis (PFMA). The process by which the site-specific PFMs are identified, described in detail, and evaluated to determine the likelihood and confidence of occurrence.
4.25 Probable Maximum Flood (PMF). The flood that may be expected from the most severe combination of critical meteorologic and hydrologic conditions that are reasonably possible in the drainage basin under study.
4.26 Probable Maximum Precipitation (PMP). The theoretically greatest depth of precipitation for a given duration that is physically possible over a drainage basin.
4.27 Reservoir. A body of water impounded by a dam.
4.28 Restriction Order. An order issued by the State Engineer to limit the water surface elevation of a reservoir to no greater than the safe storage level.
4.29 Risk. The product of (1) the likelihood of a structure being loaded, (2) the likelihood of adverse structural performance, and (3) the magnitude of the resulting consequences.
4.29.1 Risk Management. Action implemented to communicate the risks and either accept, avoid, transfer, or control the risks to an acceptable level considering associated costs and benefits of any action taken.
4.29.2 Risk Analysis. Qualitative or quantitative procedures that consider likelihood of failure and magnitude of resulting consequences to evaluate the significance of PFMs.
4.30 Safe Storage Level. The maximum reservoir water surface elevation at which the State Engineer has determined that the dam is safe to impound water based on the safety inspection and/or evaluations.
4.31 Safety Inspection. An evaluation by an Engineer in accordance with section 37-87-107, C.R.S., used by the State Engineer to set the safe storage level. The inspection shall include a review of the Emergency Action Plan and the hazard classification of the dam.
4.32 Spillway. An overflow structure through which inflow is discharged from a reservoir.
4.32.1 Service Spillway. The overflow structure designed to limit or control the operating level of a reservoir.
4.32.2 Emergency Spillway. The overflow structure designed to pass the Inflow Design Flood.
4.32.3 Spillway Crest. The elevation of the spillway at which uncontrolled discharge begins.
4.33 Storage.
4.33.1 Normal Storage. Volume of the reservoir impounded by a dam below the normal water line.
4.33.2 Maximum Storage. Volume of the reservoir impounded by a dam below the dam crest.
4.33.3 Flood Storage. Volume of water temporarily stored within a reservoir between the normal water line and the crest of the dam.
Rule 5. Determination of Safe Storage Level 5.1 Authority to Determine Safe Storage Level. The State Engineer is assigned the responsibility to determine the safe storage level for every reservoir in the state in accordance with section 37- 87-107, C.R.S. The Owner shall not store water in excess of the amount so determined by the State Engineer to be safe.
5.2 Methods to Determine Safe Storage Level. The State Engineer will use the following methods to determine the safe storage level:
5.2.1 Safety Inspection. The State Engineer shall perform regular dam safety inspections at a frequency appropriate to the hazard classification of the dam. These inspections will be performed using current observation methods and tools, and adhere to current standards. Observations will be recorded in a standardized report format, and provided to the Owner following the inspection. Interim dam safety inspections may also be performed between regular inspection cycles when warranted by either the condition of the dam or events impacting the safety of the dam.
5.2.2 Potential Failure Modes Analysis. Potential Failure Modes Analysis may be performed following identification of a concerning issue during the regular or interim inspection and/or as part of a periodic comprehensive dam safety evaluation.
5.3 Restriction of Storage. If problems affecting the safe storage level of the reservoir are discovered, the State Engineer will issue a restriction order as an interim measure until the problems have been resolved. The Owner shall comply with the restriction order at all times. The restriction order will be removed or revised by the State Engineer only after acceptance of repairs or approval of engineering evaluations indicating the problems have been adequately resolved.
5.4 Review of Hazard Classification. As part of the determination of the safe storage level, the State Engineer will periodically review the hazard classification of existing dams by evaluating the consequences of failure applying the definitions of Rule 4.13. If the State Engineer's review indicates the consequences of failure have changed within the dam failure inundation area, the State Engineer will assign an appropriate new hazard classification. The State Engineer will require the dam to meet the requirements of these Rules as they apply to the new hazard classification within a reasonable period of time.
Rule 6. Design Submittal Requirements 6.1 An Owner proposing to construct a new jurisdictional dam or alter, modify, repair, or enlarge an existing jurisdictional dam and/or appurtenant structures shall submit an application package in a form acceptable to the State Engineer. Construction activities may not commence until the State Engineer has provided written approval of the design.
6.2 Pre-Design Meeting. Prior to design commencement, the Owner and Engineer shall meet with the State Engineer to discuss the project scope, objectives, and selected design criteria. Meeting minutes shall be provided by the Engineer to establish a clear understanding of the project requirements.
6.3 Application Package. The application package shall meet the following criteria:
6.3.1 Format. The application package shall be submitted in portable digital file (PDF) format unless otherwise requested by the State Engineer. All electronic submissions shall consider the following:
6.3.1.1 File Size. Efforts shall be made to minimize digital file size from the earliest stages of document development. Efforts may include use of file compression techniques in each step of the document development.
6.3.1.2 Appropriate Security Settings. Security settings shall allow for the required digital review and approval process by the State Engineer.
6.3.1.3 Appropriate Resolution. Digital files shall include a resolution appropriate to allow for printing both 22- by 34-inch and 11- by 17-inch (half-size) drawings without losing clarity, quality, or scalability.
6.3.1.4 Electronic Signatures. Appropriate engineering stamps and signatures will be required on the final version of the design documents before construction approval will be granted.
6.3.1.5 File Name. A table with document name, document description, and document type of all materials in the application package shall be included.
6.3.1.6 File Transfer. Digital file transfer methods shall be discussed and arranged in consultation with the State Engineer.
6.3.2 Content. The application package shall include the following:
A. Application Form, B. Engineer’s Qualification Statement and Affidavit, C. Construction Plans, D. Construction Specifications, E. Design Report, F. Inundation Map (High and Significant Hazard dams only), G. Cost Estimate, and H. Filing Fee.
6.4 Application Form. A completed application form shall be provided to the State Engineer. The application shall be signed by the Owner or an authorized representative of the Owner. The Engineer may act as the Owner’s representative if authorized by the Owner.
6.5 Engineer’s Qualification Statement and Affidavit. The Engineer shall submit qualifications and a signed affidavit attesting compliance with the requirements as defined in Rule 4.10.
6.6 Construction Plans. 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. Construction plans shall meet the following requirements:
6.6.1 Contents. The plan set shall contain the following features:
6.6.1.1 The Engineer’s seal in accordance with current practice defined by The Bylaws and Rules of Procedure of the State Board of Registration for Architects, Professional Engineers, and Professional Land Surveyors (4 CCR 730-1).
6.6.1.2 A cover sheet with the following information at a minimum:
6.6.1.3 A list of the drawings that follow the cover sheet, placed on the second sheet of the plans, and a note on the cover sheet indicating the location of the list of the drawings.
6.6.1.4 The Engineer's certification statement, the State Engineer's approval signature block, and the Engineer's as-constructed statement in the lower right quadrant of the cover sheet in the following format:
These plans have been prepared by me or under my direct supervision. ______________________________ [Engineer’s Printed Name] Engineer’s Colorado P.E. No. [xxxxx] Stamp (1-5/8 inches)
Approved on the _______day of __________20___ ____________________________________ State Engineer State Engineer’s By:____________________________ Stamp [Name], Chief, Colorado Dam Safety (1-5/8 inches)
Colorado P.E. No. [xxxxx] These plans represent the AS-CONSTRUCTED conditions of _______________ Dam to the best of my knowledge and judgment, based in part on information furnished by others, as of the ______ day of __________, 20__.
______________________________ Engineer’s [Engineer’s Printed Name] Stamp Colorado P.E. No. [xxxxx] (1-5/8 inches)
6.6.1.5 When appropriate, stage discharge curves and tables for spillways and outlets shall be placed on the drawings. For spillways, the curves and tables shall include the discharge for each vertical foot between the spillway crest and dam crest. For outlets, the curves and tables shall include the discharge for each vertical foot between the invert of the outlet works intake and the dam crest. Crest elevations of all spillways and the dam, and the invert elevation of the outlet shall be clearly noted on the tables. The rating data shall be referenced to both gage height and elevation.
6.6.1.6 Area capacity and stage capacity curves and tables shall be provided for all new dams and enlargements and when otherwise determined appropriate. The curves and tables shall be provided in a format determined in consultation with the State Engineer.
6.6.1.7 The plans shall clearly identify the vertical and horizontal datum used, and to the extent possible, shall include a description of vertical and horizontal translations if the proposed datum is different from that used in past projects for the same dam.
6.6.1.8 In no cases shall construction specifications be provided on the drawings.
6.6.2 Format. All plan sets shall meet the following format requirements:
6.6.2.1 Drawings shall be prepared in an appropriate scale so details and text are clearly legible on an overall sheet size of 22- by 34-inches and half-size sheet size of 11- by 17-inches.
6.6.2.2 Drawings shall have bar scales to allow scaling of reduced-sized drawings.
6.6.2.3 Full size drawings shall have a 1/2- by 3-inch space for the State Engineer's construction file number inside the margin in the lower right-hand corner. A unique construction file number will be assigned by the State Engineer prior to final approval of the project documents for construction and shall be placed in bold characters on all of the drawings.
6.6.2.4 Each sheet shall be numbered sequentially with the first sheet being sheet number one along with the total number of sheets (e.g., sheet 1 of 6).
6.7 Construction Specifications. Construction Specifications shall be submitted on 8½- by 11-inch paper in PDF format, and in printed format if requested by the State Engineer. Specifications shall meet the following requirements:
6.7.1 The specifications shall display the Engineer’s seal in accordance with current practice defined by The Bylaws and Rules of Procedure of the State Board of Registration for Architects, Professional Engineers and Professional Land Surveyors (4 CCR 730-1).
6.7.2 The cover sheet shall show the following information at a minimum:
A. The name of the dam;
B. The county, Water Division, and Water District in which the dam is located;
C. DAMID;
D. State Construction File Number; and E. Date.
6.7.3 The first page behind the cover shall show the following information at a minimum:
A. The same information as on the cover sheet; and B. The Engineer's certification statement with seal and signature, and the State Engineer's approval statement as shown in Rule 6.6.1.4 (without the As- Constructed block).
6.7.4 The specifications shall have an index.
6.7.5 Printed specifications shall be bound. Loose-leaf and 3-ring binders are not acceptable.
6.7.6 The specifications shall include a separate section with the following provisions stating the State Engineer’s authority:
6.7.6.1 The plans and specifications cannot be significantly changed without the prior written approval of the State Engineer. If changed conditions are encountered after the State Engineer’s approval is issued, the changes shall be documented in accordance with Rule 8.2.5.
6.7.6.2 Construction shall not be considered complete until the State Engineer has accepted the construction in writing.
6.7.6.3 The Engineer will monitor the quality of construction as specified in Rule 8.1.2. The Engineer monitoring the construction for the Owner is responsible for compliance with the approved design and specifications, preparation of the necessary documentation for the State Engineer’s review and approval of all design change orders, and preparation of the project completion documents, and for recommending the project for acceptance to the State Engineer.
6.7.7 The specifications shall include the following at a minimum:
A. Quality of materials used in construction, B. Acceptable quality of workmanship, C. References to applicable standards as appropriate, D. Required tests and estimated frequency of testing, and E. Action to be taken if unsatisfactory materials or workmanship are discovered in the construction.
6.7.8 Only technical specifications shall be submitted. No contract documents or extraneous specifications unrelated to the project shall be included.
6.8 Design Report. A design report shall be submitted with the application package. The purpose of the design report is to present the project design criteria and all supporting engineering analyses including applicable design standards and references. The design report shall display the Engineer’s seal in accordance with current practice defined by The Bylaws and Rules of Procedure of the State Board of Registration for Architects, Professional Engineers and Professional Land Surveyors (4 CCR 730-1). The following topics shall be addressed in the design report when applicable to the proposed project. Stand-alone reports addressing individual topics shall be sealed by the Engineer and summarized in the design report.
6.8.1 Introduction. This section shall describe the project and review process, including a discussion of the project objectives and how the proposed design will meet those objectives.
6.8.2 Project Components. This section shall describe the dam, spillway, outlet works, and other appurtenant structures.
6.8.3 Site Requirements. This section shall describe any site improvements and unusual construction considerations required to construct the project.
6.8.4 Hazard Classification. This section shall identify the hazard classification for the dam. This may be submitted, reviewed, and approved as a stand-alone report prior to submittal of the application package. A detailed analysis is not required for dams that are declared as High Hazard; however, a dam failure inundation map will be required for the Emergency Action Plan pursuant to Rule 13.7.
6.8.5 Hydrology. This section shall include all pertinent design analyses and assumptions necessary to determine the inflow design flood (IDF) for sizing the spillway in accordance with Rule 7.2. This may be submitted, reviewed, and approved as a stand-alone report prior to submittal of the application package.
6.8.6 Hydraulics. This section shall discuss how the proposed spillway design will protect the dam from damage during the IDF and how the proposed outlet will comply with the downstream delivery and reservoir evacuation requirements.
6.8.7 Geotechnical Design. This section shall include all pertinent geotechnical and engineering geology considerations for a given project. Documentation and interpretation of all appropriate field and laboratory testing programs shall be sufficiently comprehensive to support the basis of design for dam and appurtenant structure foundations. This may be submitted and reviewed as a stand-alone report prior to submittal of the application package.
6.8.8 Structural Design. This section shall include discussion of the design and analyses for all structural components.
6.8.9 Instrumentation Plan. This section shall describe the objectives and details of the proposed instrumentation.
6.8.10 Mechanical and Electrical Design. This section shall include discussion of designs and analyses for all mechanical and electrical systems including, but not limited to, gates, valves, trash racks and mechanical systems, systems for operating gates and valves, electrical power requirements and emergency backup power or manual override.
6.8.11 River Diversion during Construction. This section shall describe the means to protect the proposed work, the stream, and public safety during the proposed construction period as required by Rule 8.1.1.
6.9 Cost Estimate. A detailed cost estimate of the construction of the dam including the engineering and construction oversight tasks. The cost estimate will remain confidential until after the construction contract is executed.
6.10 Fee. A fee shall be assessed in accordance with section 37-80-110(1)(e), C.R.S. A check for the fee shall accompany the application form and be made payable to Colorado Division of Water Resources.
6.11 Design Review Approvals and Limitations.
6.11.1 Approval of Plans and Specifications. The State Engineer will approve acceptable plans and specifications for construction. Unacceptable submittals will be rejected.
6.11.2 Design Review Limitation. Re-submittal of the design package shall be required if resolution of the design review comments does not occur within three years. Resubmitted designs shall be accompanied by a new application package and fee.
6.11.3 Approval Limitation. Construction shall commence within five years of approval of the application, after which time the State Engineer's approval shall be void. The new application will be reviewed and reevaluated against current standards. Resubmitted designs shall be accompanied by a new application package and fee.
6.11.4 Resubmittal of Rejected Designs and Expired Approvals. The Owner is required to submit a complete application package and fee, addressing any previously identified deficiencies, before the design will be reconsidered. The new application will be reviewed and reevaluated against current standards.
6.12 Application and Approval Requirements for Low Hazard and NPH Dams. Plans for alteration, modification, repair, or enlargement of an existing Low Hazard or NPH dam and/or appurtenant structures of Low Hazard dams or NPH dams will be reviewed in accordance with the following procedure:
6.12.1 Notice. The Owner shall provide written notice to the State Engineer at least thirty (30) days in advance of construction. The written notice shall contain the name of the dam, the location of the dam, the name of the Owner, contact information for the Owner, and a clear description of the work to be performed.
6.12.2 Determination. The State Engineer will notify the Owner whether plans and specifications are required.
6.12.2.1 If plans and specifications are required, Rules 6, 7, and 8 will apply.
6.12.2.2 If plans and specifications are not required, the State Engineer will inform the Owner of any engineering, construction, and project documentation requirements, and will perform construction inspections as determined necessary.
Rule 7. Design Requirements 7.1 This Rule applies to design of new dams and alteration, modification, repair, or enlargement of existing dams. In the case of existing dams, only the pertinent sections will apply.
7.2 Inflow Design Flood (IDF) for Spillway Sizing.
7.2.1 Prescriptive Method. Table 7.1 provides rainfall requirements for the Inflow Design Flood (IDF) based on Hydrologic Hazard. The spillway must safely route a flood generated by Critical1 Rainfall shown in Table 7.1.
Table 7.1: Prescriptive IDF Requirements Hydrologic Hazard Critical1 Rainfall Probable Maximum Extreme Precipitation (PMP)
7.2.2 Consequence Estimation. Consequence estimation for Hydrologic Hazard may be determined based on total flood depth associated with an overtopping (or other plausible hydrologic failure mode) dam failure flood or based on the incremental consequences between such dam failure flood and that caused by the spillway base flood immediately prior to dam failure. The spillway size is acceptable when it meets or exceeds the IDF requirements of Table 7.1 for a given Hydrological Hazard category.
7.2.3 Allowable Rainfall Estimates for developing the IDF.
7.2.3.1 Probable Maximum Precipitation (PMP). The Probable Maximum Flood (PMF)
7.2.3.2 Precipitation Frequency Estimates. Frequency-based IDFs shall be developed using the most current precipitation frequency estimates approved by the State Engineer.
7.2.3.3 Site-Specific Extreme Precipitation Studies (SSEPS). SSEPS may be used to determine the appropriate site-specific extreme storm precipitation (PMP or precipitation frequency estimates) for the determination of the IDF. The SSEPS must be approved by the State Engineer prior to acceptance.
7.2.4 Atmospheric Moisture Factor. All rainfall depth estimates calculated by means acceptable to the State Engineer shall be multiplied by a factor of 1.07 prior to calculating runoff to account for expected increases in temperature and associated increases in atmospheric moisture availability over the 50-year period 2020 to 2070.
7.2.5 Flood Frequency Analysis. Using systematic records, historical flood information, and paleoflood and botanical information, flood frequency analysis may be used to determine a required frequency flood for spillway sizing purposes. Flood frequency analysis shall follow applicable, current, published guidelines and procedures, such as Guidelines For Determining Flood Flow Frequency (ACWI Bulletin 17C, USGS, 2018).
7.2.6 Hydrologic Basin Response Requirements. Rainfall-runoff modeling used to develop an IDF shall consider basin size, elevation of the basin, various soil permeabilities, various vegetative covers, and other factors related to the routing of the storm event. Snowmelt conditions and rain-on-snow events shall be considered as base flow when appropriate.
7.3 Geological and Geotechnical Investigations.
7.3.1 Geological and geotechnical engineering investigations shall be conducted under the supervision of an Engineer or Geologist experienced in geotechnical or geological engineering for dams.
7.3.2 Geological Site Characterization. A geological assessment of the dam and reservoir site is required for all dams classified as High or Significant Hazard. The geological assessment shall include, at a minimum:
A. Regional geologic setting;
B. Local and site geology;
C. Geologic suitability of the dam foundation, reservoir rim stability, and reservoir area leakage;
D. Regional and site seismicity;
E. All other potential geological hazards affecting the project; and F. A site-specific geologic map based upon published records and field observations. The geologic mapping shall cover the reservoir area, dam, abutments, and the locations of all appurtenant structures.
7.3.3 Subsurface Investigation Plans. A subsurface investigation plan must be approved by the State Engineer prior to mobilization for all proposed subsurface investigations. The plan shall include the following:
A. Objective(s) of the investigation and descriptions of the specific Potential Failure Modes being addressed in the investigation;
B. Names and qualifications of the investigation team including lead geotechnical or geological engineer, field engineers, and geologists;
C. Figures and description of the existing conditions;
D. Drilling, test pits, and other in-situ testing procedures; and E. Contingency plans.
7.3.3.1 Drilling methods in all dams and dam foundations shall be chosen to minimize the risk of hydraulic fracturing or otherwise damaging the strata or formations being drilled. Drilling on or within 200 feet of existing dams is prohibited unless approved by the State Engineer.
7.3.4 Subsurface Geotechnical Investigations. Subsurface investigations shall be conducted for all new dams and for all modifications to existing dams where appropriate. The subsurface investigation shall include a characterization of the geotechnical and geologic foundation conditions as follows. More extensive investigation and reporting may be required, depending on project-specific needs.
7.3.4.1 High and Significant Hazard Dams. Subsurface geotechnical investigations for High and Significant Hazard dams shall require the following, at a minimum:
7.3.4.2 Low Hazard and NPH Dams. Subsurface geotechnical investigations for Low
7.3.4.3 Spillways, Outlet Works, and Appurtenant Structures. Subsurface
7.3.4.4 Underground Construction. Where tunneling or other underground
7.3.4.5 Borrow Sources.
7.3.5 Laboratory Testing. Laboratory testing of all proposed native and imported construction materials, and foundation and abutment materials, shall be performed to provide engineering justification for the selected design criteria.
7.3.5.1 High and Significant Hazard Dams. Laboratory testing for High and Significant Hazard earth and rockfill embankment dams shall include the following tests, at a minimum:
7.3.5.2 Low Hazard and NPH Dams. Laboratory testing for Low Hazard and No Public Hazard earth and rockfill embankment dams shall include the following tests, at a minimum:
7.4 Embankment Dam Design.
7.4.1 Foundation and Abutment Design. The dam foundation and abutments shall be
analyzed and design criteria selected to meet the following requirements:
7.4.1.1 Unsuitable materials shall be removed from the dam foundation and abutments, unless appropriate analyses demonstrate the unsuitable material can be adequately treated so it will not adversely affect the safety and performance of the dam. Unsuitable materials include, but are not limited to liquefiable, dispersive, organic, expansive, and collapsible soils; slaking shales; soluble rock; clay seams in rock; and poor-quality rock.
7.4.1.2 The dam foundation geometry shall be designed to prevent the creation of low stress zones in the embankment that could cause differential settlement and cracking of the dam.
7.4.1.3 The foundation shall be treated as required to prevent deformation or instability of the dam caused by foundation movement as a result of heave, swell, rebound, settlement, or collapse.
7.4.1.4 Seepage Control and Foundation Drainage Design Criteria.
7.4.2 Embankment Design Requirements. The dam embankment shall be analyzed and
designed to meet the following requirements:
7.4.2.1 Crest Design.
7.4.2.2 Freeboard Design. Freeboard for earth and rockfill embankment dams shall be designed in accordance with Freeboard (Design Standard No. 13, Chapter 6, Reclamation, 2012), except as follows:
7.4.2.3 Embankment Zoning. Shells, cores, filters, and drains for embankment dams shall be designed using industry standards consistent with the current state of the practice.
7.4.2.4 Seepage and Internal Drainage Design. Evaluation of steady state seepage and internal drainage conditions shall be performed. The seepage and internal drainage design shall include, but not be limited to, the following:
7.4.2.5 Embankment Stability.
7.4.2.6 Settlement and Consolidation. All dams shall be analyzed and designed to prevent deformation or instability caused by movement as a result of settlement, consolidation, or collapse.
7.4.2.7 Cracking. All dams shall be analyzed and designed to prevent the formation of cracks due to differential settlement or creation of low stress zones that could lead to hydraulic fracturing.
7.4.2.8 Upstream Slope Erosion Protection. Embankments shall be protected against external erosion. Slope protection for wave action is required to be provided on the entire upstream slope of the dam, unless lesser coverage is justified based on engineering analysis and reservoir operational criteria.
7.4.2.9 Downstream slope erosion protection. The downstream slope of earth
7.4.2.10 Geosynthetics. The use of geosynthetics shall be evaluated by the
7.4.3 Material Placement and Compaction Requirements. Material placement and
compaction shall meet the minimum requirements:
7.4.3.1 Minimum compacted density for embankment materials shall be 95 percent of maximum dry density for ASTM D698 (Standard Proctor).
7.4.3.2 Impervious zones with clay fines shall be placed at close to optimum moisture content to prevent overcompacted, brittle zones.
7.4.3.3 The density for cohesionless filter and drain materials shall range between 65- and 75-percent relative density as determined by ASTM D4253 and D4254, or other method(s) approved by the State Engineer.
7.4.3.4 Construction of filters and drains shall be based on placement procedures developed through a test fill program to verify acceptable density and avoid excessive particle breakdown.
7.4.3.5 Filter and drain zones shall be constructed with sufficient thickness to prevent contamination or loss of continuity that would adversely impact the performance of these features.
7.5 Concrete Dam Design Requirements.
7.5.1 For all concrete dams, the following design considerations shall be addressed and documented in the Design Report:
7.5.1.1 The crest of the dam shall have a width of not less than 5 feet.
7.5.1.2 If the crest of the dam is designed to function as the emergency spillway, it shall not be overtopped by floods more frequent than the one percent AEP flood.
7.5.1.3 Emergency spillway discharge for flows up to the inflow design flood shall not cause excessive downstream erosion of the abutments and foundation.
7.5.1.4 The design shall include provisions for installation, maintenance, and monitoring of drainage features.
7.5.1.5 A concrete mix design containing proposed aggregate properties, source of aggregate, concrete properties, and proposed cementitious contents shall be provided.
7.5.1.6 Specifications shall include provisions for placing concrete under cold weather, hot weather, and rain.
7.5.2 Arch Dams. Concrete arch dams shall be designed in accordance with principles provided in Arch Dam Design (EM 1110-2-2201, U.S. Army Corps of Engineers,1994), Design Criteria for Concrete Arch and Gravity Dams (Engineering Monograph No. 19, U.S. Bureau of Reclamation, 1977), Design of Arch Dams (U.S. Bureau of Reclamation, 1977), or Arch Dams (Chapter 11, Federal Energy Regulatory Commission, 2018).
7.5.3 Gravity Dams. Concrete gravity dams shall be designed in accordance with the following Rules and Gravity Dam Design (EM 1110-2-2200, U.S. Army Corps of Engineers, 1995), Design Criteria for Concrete Arch and Gravity Dams (Engineering Monograph No. 19, U.S. Bureau of Reclamation, 1977), Design of Gravity Dams (U.S. Bureau of Reclamation, 1976), or Gravity Dams (Chapter 3, Federal Energy Regulatory Commission, 2016) with the following additions:
7.5.3.1 When the design relies on the reduction of uplift pressures from dam and foundation drains, the effectiveness of the drains shall be verified and monitored for the life of the dam via the installation of piezometers.
7.5.3.2 If the seismic loading scenario shows a crack may form along the base of the dam or the foundation may sustain damage, a post-earthquake analysis will be required to show that the dam and foundation can withstand the usual and unusual loading conditions in their “damaged” state.
7.5.3.3 Dams in excess of fifty feet in height shall include a drainage gallery.
7.5.4 Roller Compacted Concrete (RCC) Dams. Roller compacted dams shall be designed in accordance with the following Rules and Roller-Compacted Concrete (EM 1110-2-2006, U.S. Army Corps of Engineers, 2000) or Roller-Compacted Concrete (U.S. Bureau of Reclamation, 2017) with the following additions:
7.5.4.1 The dam design shall include adequate control of cracking in the upstream facing system and concrete mass caused by thermal shrinkage of the concrete. Crack control provisions shall include controlling excessive heat of hydration by use of fly ash and limiting in-place concrete temperature.
7.5.4.2 Adequate cold joint treatment shall be provided in the specifications to prevent formation of unbonded lift joints that could become potential paths for seepage.
7.5.4.3 Design dimensions shall be able to be constructed with conventional earthwork equipment, particularly between the upstream face of the dam and the drainage gallery, and within the chimney section.
7.5.4.4 RCC shall be protected with conventional facing concrete, or equivalent
7.5.4.5 Material Placement. The construction of RCC dams shall meet the following requirements:
7.6 Seismic Design Requirements. Seismic stability shall be evaluated for all concrete dams and High and Significant Hazard embankment dams. The level of analysis required shall be commensurate with the known and anticipated site conditions and the level of effort given to developing input parameters. In general, analyses should start at a screening level and progress to more detailed analyses only when necessary. Seismic stability analyses shall be based on the principles provided in Earthquake Analyses and Design of Dams (FEMA-65, Federal Guidelines for Dam Safety, FEMA, 2005), Best Practices Chapter II-3 (Reclamation and U.S. Army Corps of Engineers, 2015), Seismic Analysis and Design (Design Standards No. 13 Chapter 13, Reclamation, 2015), Earthquake Design and Evaluation for Civil Works Projects (Engineering Regulation 1110-2-1806, U.S. Army Corps of Engineers, 2016), or Earthquake Design and Evaluation of Concrete Hydraulic Structures (Engineering Manual 1110-2-6053, U.S. Army Corps of Engineers, 2007).
7.6.1 Seismic Hazard Analysis. The seismic hazards, consisting of the design earthquakes and associated ground motions, shall be determined. The seismic hazards shall be justified with due consideration to the hazard classification of the structure, regional and site-specific seismic hazard considerations, and the designated operational function of the dam.
7.6.2 Dynamic Response Analysis. Analyses to predict the structural response to seismic loading are required except as described in Rule 7.6.2.1. All seismic analyses shall be evaluated assuming loading and pore pressure conditions expected immediately prior to the earthquake. Acceptable methods for predicting structural response to seismic loading include, but are not limited to, post-earthquake stability, embankment deformation, and probabilistic analyses. Pseudostatic analyses are not an acceptable means of predicting structural response to seismic loading.
7.6.2.1 Dynamic Response Analyses are not required for embankment dams meeting all of the following conditions. The potential for embankment cracking (transverse or longitudinal), damage to appurtenant features (e.g., outlet-works tunnels), and overtopping due to seiche waves as the result of seismic activity are not addressed by these exceptions and shall be considered separately.
7.7 Instrumentation and Monitoring Requirements.
7.7.1 The Owner shall submit a plan for installation of all new instrumentation and flow measurement devices for review and approval.
7.7.2 Instrumentation Plan. An instrumentation plan is required and shall meet the following requirements:
7.7.2.1 All instrumentation shall be properly identified in the field to correspond to the identification of the instrumentation in the long-term monitoring plan required in Rule 13.4.
7.7.2.2 Gage rods shall be installed at all dams to accurately measure reservoir levels. The zero mark of the gage shall be aligned vertically with the invert elevation of the entrance to the outlet. The gage rod shall be located in an easily accessible location and 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.
7.7.2.3 High and Significant Hazard Dams. High and Significant Hazard dams shall have the following minimum instrumentation:
7.7.2.4 Low Hazard Dams. Low Hazard dams shall have weirs, flumes or other
7.8 Spillway and Outlet Works Design Requirements.
7.8.1 Spillway Design. All spillways shall be designed and constructed in a manner acceptable to the State Engineer and to meet the following criteria:
7.8.1.1 The starting water surface elevation when routing the IDF shall be the
7.8.1.2 The spillway shall safely route the IDF back to the natural channel or drainage way that would exist if the dam were not built. The Owner shall possess title to the property, a right-of-way, or easement from the high water line in the reservoir to the natural channel, including the stilling basin downstream.
7.8.1.3 Log booms or other methods approved by the State Engineer shall be installed in the spillway approach where logs and other debris may block spillway flow or damage the spillway structure.
7.8.1.4 Pipe emergency spillways are not acceptable.
7.8.1.5 The design report shall include discharge tables (in cubic feet per second) for all spillways showing the discharge for each foot of head between the crest of the spillways and dam. The equation(s) used for determining the discharge shall also be included. Crest elevations of all spillways and the dam shall be clearly noted on the tables.
7.8.1.6 Overtopping Protection Design. Overtopping protection for existing
7.8.2 Outlet Works Design. All outlet systems shall be designed and installed in a manner acceptable to the State Engineer and shall meet the following criteria:
7.8.2.1 Outlets shall be capable of releasing the top five feet of the reservoir capacity in five (5) days. Final outlet size should reflect consideration of seasonal reservoir inflows and consequences of releases or dam failure. The outlet shall be capable of releasing the entire reservoir in a reasonable period of time. In addition, outlets shall be capable of passing inflow to the reservoir with a minimum of ten feet of head, in order to meet the demands of downstream senior water rights and the Owner's release requirements. The minimum size required for outlet conduits and controls is 12 inches.
7.8.2.2 All outlets connected to a pipeline shall have a bypass valve near the dam that will meet the capacity criteria as defined in Rule 7.8.2.1.
7.8.2.3 Outlet conduits for all dams, except for dams with ungated outlets, shall have a guard gate installed at the upstream end of the conduit.
7.8.2.4 Intake structures for outlet works shall have trash racks.
7.8.2.5 The Design Report shall include an outlet discharge table (in cubic feet per second) showing the discharge for each foot of head between the invert of the intake structure and the crest of the dam. The equation(s) used for determining the discharge shall also be included. Elevations of all outlets and spillways shall be clearly noted on the table.
7.9 Reservoir and Site Requirements.
7.9.1 The area to be submerged by the new or enlarged reservoir shall be cleared of trees and debris.
7.9.2 The dam crest and appurtenant structures shall be accessible by equipment and vehicles for emergency operations and maintenance.
7.9.3 The Owner shall demonstrate ownership or recorded easement for the following:
7.9.3.1 Footprint of the dam, appurtenant structures, and permanent access for a minimum distance of 50 feet or the height of the dam, whichever is greater, extending downstream from the toe of the dam.
7.9.3.2 Spillway discharge channels meeting the requirements of Rule 7.8.1.2.
7.9.3.3 All areas inundated by the reservoir and IDF surcharge.
7.9.4 Pipelines, utility lines, or any other construction that penetrates through the dam, abutment areas below the dam crest elevation, or that are within a distance of 50 feet or the height of the dam, whichever is greater, from either toe of the dam shall not be allowed without prior written approval by the State Engineer. Rule 8. Construction Requirements
8.1 Pre-Construction.
8.1.1 Water Diversion Plan.
8.1.1.1 A plan to control surface water during construction shall be developed by the construction contractor based on information and requirements provided by an Engineer. The plan shall state the return interval or annual exceedance probability for the storm event the system is designed to protect against. The plan shall be prepared under the direction of an Engineer meeting the requirements of Rule 4.10.
8.1.1.2 The plan shall be approved by the Engineer and submitted to the State Engineer in advance of construction of the diversion facilities.
8.1.1.3 A hazard classification evaluation shall be performed by an Engineer based on consequences to the public for any proposed cofferdam. If the water diversion system is found to be High or Significant Hazard, the design shall meet the requirements of Rule 7.
8.1.1.4 The water diversion plan shall address the removal or abandonment of
8.1.2 Construction Observation Plan. Not less than thirty (30) days prior to construction, the Engineer shall submit a construction observation plan to the State Engineer. The construction observation plan shall include, at a minimum:
A. The anticipated date of the start of construction;
B. Names and resumes of the Engineer and staff to be used on the project;
C. A construction observation schedule for the Engineer and staff;
D. For dams on rock foundations, a schedule for observations of the foundation by a Geologist;
E. A quality assurance plan including a schedule of the construction material tests; and F. Identification of the firm and qualifications of the personnel that will conduct the construction material tests in the field and in the laboratory.
8.1.2.1 Approval. Within fourteen (14) days of receipt, the State Engineer shall provide written comments and approval, or conditions for approval, of the construction observation plan. Construction shall not commence without approval of the observation plan by the State Engineer.
8.1.3 Pre-Construction Meeting. Prior to commencement of construction, a meeting shall be held between the Engineer, Owner, State Engineer, and contractor. The State Engineer shall be notified at least fourteen (14) days prior to the meeting. The contractor shall present and thoroughly explain its construction work plan along with any anticipated construction difficulties. The name of the subcontractors shall be furnished to the State Engineer at the meeting. Project communication protocol between the Owner, Engineer, and the State Engineer shall be established at the pre-construction meeting.
8.2 Construction.
8.2.1 Engineer’s Observation. The Engineer shall observe the progress and quality of the construction in accordance with the approved construction observation plan. 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. In cases where the Engineer has a contractual relationship with the contractor to provide engineering services, the Owner shall provide an independent, third-party engineer to perform the engineering quality assurance observations.
8.2.2 Construction Records. The Engineer shall maintain a record of construction that, at a minimum, shall include daily activity and progress reports, design change orders, all materials testing results, gate and valve installation certifications, photographs sufficient to provide a record of foundation conditions and various stages of the construction through completion, all geologic information obtained, and documentation of any construction problems and remedies.
8.2.3 Progress Reports. Progress reports summarizing the status of the work shall be submitted to the State Engineer during the project at a minimum frequency and in a format agreed upon during the pre-construction meeting. The progress report shall include the contractor’s three-week look-ahead schedule.
8.2.4 Notice for Inspection. The Engineer shall give the State Engineer at least five (5) days advance notice of any work items listed by the State Engineer in the pre-construction meeting, to allow for observation by the State Engineer.
8.2.5 Design Change Order. When unforeseen site conditions or material availability require that the construction work differ significantly from the approved plans and specifications, a design change order, including details, shall be provided by the Engineer to the State Engineer. No change shall be executed until approved by the State Engineer. Major changes shall be submitted in writing with supporting documentation, and approved in writing by the State Engineer. Minor changes, as determined by the State Engineer, may be approved verbally and documented in the final construction documents.
8.2.6 Final Inspection. The Engineer shall give the State Engineer at least fourteen (14) days advance notice prior to the project’s final construction inspection. The Engineer shall document the completion of any punch list items.
8.3 Acceptance of Construction. Construction 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. The acceptance shall state the as-constructed dam dimensions, the capacity of the reservoir, and any limitations upon or requirements for the use of the dam. The State Engineer shall furnish the acceptance or denial within sixty (60) days of receipt of construction completion documents as outlined below.
8.3.1 Construction Completion Documents. The Engineer shall provide the following construction documentation within sixty (60) days of the final construction inspection:
8.3.1.1 A written notification that the project is complete and in general conforms with the approved plans, specifications, and design change orders.
8.3.1.2 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.
8.3.1.3 As-constructed plans showing the original approved plans amended to include any major or minor changes.
8.3.1.4 A final construction report summarizing construction, problems encountered and solutions implemented to resolve the problems, and compiling the construction records as identified in Rule 8.2.2.
8.3.1.5 A record of the location of permanent monuments and instrumentation as well as installation details and initial surveys and readings, if applicable.
8.3.1.6 The approved dam observation and monitoring plan in accordance with Rule 13.4.
8.3.1.7 A new or updated Emergency Action Plan including current inundation map in accordance with Rule 13.7.
8.3.2 For new dams and enlargements, the Engineer shall provide periodic review of the data included in the dam observation and monitoring plan on at least an annual basis for the first five years following construction completion. The Engineer shall submit the data and a written assessment of the dam's performance to the State Engineer annually.
8.3.3 Temporary Approval. Upon written request by the Owner and for good cause shown, the State Engineer may temporarily approve storage of water prior to submitting the construction completion documents. Only a partial reservoir filling will be granted under this Rule. Final acceptance of the construction for full use of the reservoir will not be granted until the requirements of Rule 8.3 have been satisfactorily completed. The written request shall include, at a minimum:
A. A schedule for compliance with Rule 8.3;
B. A notification letter signed and sealed by the Engineer in accordance with Rule 8.3.1.1;
C. A schedule for the first filling of reservoir in accordance Rule 8.3.1.2;
D. A monitoring plan for observing the behavior of the dam and appurtenances during the initial filling or refilling of the reservoir; and E. A new or updated EAP prepared in accordance with Rule 13.7. Rule 9. Requirements for Removing or Breaching an Existing Dam 9.1 Breach Plan and Application. An Owner proposing to permanently remove or breach a dam shall submit an application package to be approved by the State Engineer prior to commencing work. The application shall be completed on a form provided by the State Engineer and shall include the following:
9.1.1 Documentation demonstrating that notice has been given to land owners and agencies potentially impacted by removal or breach of the dam.
9.1.2 Documentation showing that all permitting requirements by local, state and federal agencies have been satisfied.
9.1.3 A breach plan meeting the following requirements:
9.1.3.1 The breach shall be designed to prevent silt previously deposited in the reservoir and material excavated for the breach from washing downstream.
9.1.3.2 Water impounded in the reservoir area shall be released in a controlled manner that will not endanger lives or damage downstream properties.
9.1.3.3 The minimum bottom width of the breach shall be one-half the height of the dam or 10 feet, whichever is greater.
9.1.3.4 The sides of the breach shall be excavated to a slope that is stable, but not steeper than 2H:1V (horizontal:vertical). A slope stability analysis that demonstrates an adequate factor of safety for slopes steeper than 2H:1V may be accepted by the State Engineer. The breach dimensions shall meet water administration requirements of the Division Engineer. The dam shall be excavated down to the level of the natural ground at the maximum section, or as otherwise necessary to comply with Rule 9.1.3.
9.1.3.5 The excavated material shall not be placed in the stream channel.
9.1.3.6 High and Significant Hazard Dams. The breach plan for High and Significant Hazard dams shall meet the following additional requirements:
10.1 Notice of Construction. Any person intending to construct a non-jurisdictional size dam other than a Livestock Water Tank or Erosion Control Dam, shall submit notice of the intent to construct the dam on forms provided by the State Engineer not less than forty-five (45) days prior to the proposed construction. The State Engineer shall determine the potential hazard for loss of life or significant damage due to failure of the structure, and if the submittal and approval of plans and specifications is required prior to construction. The forms shall be submitted to the Division Engineer of the Water Division in which the dam is to be located. The Division Engineer shall respond to the Owner within forty-five (45) days after receipt of the complete notice of intent to construct form. All Owners shall be required to comply with the applicable dam safety and water administration requirements.
10.2 Modification or Alteration of Non-Jurisdictional Size Dams. Jurisdictional size dams proposed to be modified or altered to non-jurisdictional size shall comply with the following requirements:
10.2.1 For High or Significant Hazard dams, the Owner shall submit plans for approval in accordance with Rule 6. As-constructed documents are required in conformance with Rule 8.3.1.
10.2.2 For Low Hazard or NPH dams, the Owner shall submit written notice of the intent to alter the dam to the State Engineer. The Owner shall submit written notice of the completion of the project.
10.3 Repair or Breaching of Non-Jurisdictional Dams. Repair or breaching of existing non- jurisdictional size dams shall meet the following requirements:
10.3.1 In cases where a non-jurisdictional dam has been found unsafe, the Owner shall submit written notice to the State Engineer to repair, modify, breach or entirely remove the dam prior to construction.
10.3.2 Removal or breaching of a non-jurisdictional dam shall comply with Rule 9.
10.3.3 Modifications to, or repair of, High or Significant Hazard non-jurisdictional size dams shall be performed in accordance with Rule 6.
10.4 Spillway Requirements. Spillway sizing requirements shall meet the criteria for the appropriate hydrologic hazard category.
10.5 Enlargement of Non-Jurisdictional Size Dams. The modification of a non-jurisdictional size dam to a jurisdictional size dam shall meet the requirements of Rule 6. Rule 11. General Maintenance, Ordinary Repairs, and Emergency Actions 11.1 General maintenance and ordinary repairs that do not require prior approval of the State Engineer include those activities that do not impair the safety of the dam. When questions arise concerning this Rule, the determination of general maintenance and ordinary repair will be made by the State Engineer. General maintenance and ordinary repair activities include the following:
11.1.1 Removal of brush or tall weeds.
11.1.2 Cutting of trees with trunk diameter less than 6-inches and removing slash from the embankment or spillway.
11.1.3 Rodent control, removal or extermination and repair of minor rodent damage. Damage that has already weakened the dam shall be repaired in accordance with Rule 6.
11.1.4 Repair of erosion gullies on the embankment or in the spillway. Large gullies that have already weakened the dam shall be repaired in accordance with Rule 6.
11.1.5 Surface grading of the embankment crest or spillway to eliminate potholes and provide proper drainage with properly compacted material, provided that the freeboard is not reduced. Placement of material in excess of 1 foot in depth to provide freeboard is not considered general maintenance and shall be performed in accordance with Rule 6.
11.1.6 Placement of additional riprap and bedding on the upstream slope, or in areas of the spillway that have sustained minor damage. Such placement shall be limited to restoring the original riprap protection. Repair of the underlying embankment is not considered general maintenance and shall be performed in accordance with Rule 6.
11.1.7 Painting or caulking metal structures, or lubricating mechanical equipment.
11.1.8 Patching, sealing, or caulking spalled or cracked concrete surfaces to prevent deterioration.
11.1.9 Removing debris, rock, or earth from outlet conduits, outlet channels, or spillway channels.
11.1.10 Patching or sealing surface damage to prevent further deterioration within outlet conduits.
11.1.11 Replacement of worn or damaged parts of outlet valves or controls to restore to original condition.
11.1.12 Repair or replacement of fences intended to keep traffic or livestock off the dam or spillway.
11.1.13 Landscaping of new and existing dams and spillway channels is not general maintenance and will not be allowed without the prior approval of the State Engineer. No trees or large vegetation shall be planted within 25 feet of the footprint of the dam.
11.2 Emergency Action. Emergency actions not impairing the safety of the dam may be taken before consultation and guidance can be provided by an Engineer, and do not require prior approval of the State Engineer. Emergency actions are interim solutions only and may not serve as a permanent solution to the problem(s) being addressed. Additional remedial actions may be required after the emergency passes. Emergency actions may include:
A. Stockpiling materials such as riprap, earthfill, sand, sandbags, and plastic sheeting;
B. Lowering the reservoir level by making controlled releases through the outlet or a gated spillway, by pumping, or by siphoning. Where large releases are to be made, the Division Engineer, Dam Safety Engineer and Local Emergency Manager shall be notified;
C. Armoring eroding areas by placing sandbags, riprap, plastic sheeting, or other available material;
D. Plugging leakage entrances on the upstream slope;
E. Increasing freeboard by placing sandbags or temporary earthfill on the dam;
F. Diverting flood waters around the reservoir or closing inflow diversions;
G. Constructing training berms to control flood waters;
H. Placing sandbag ring dikes around boils at the downstream toe to provide back pressure; and/or I. Removing obstructions from outlet or spillway flow areas.
11.3 Emergency Excavation. Lowering the water level by excavating the spillway or embankment is prohibited unless failure of the dam is imminent.
11.4 Emergency Notification. The State Engineer shall be notified as soon as reasonably possible of any emergency condition that exists and any emergency action taken with or without prior approval of the State Engineer.
11.5 Emergency Action Plan. For all High and Significant Hazard dams, the Emergency Action Plan shall be implemented in conjunction with any emergency actions taken. Rule 12. Safety Inspections Performed by the Owner's Engineer 12.1 Owner Safety Inspection. An Owner may provide a safety inspection report to the State Engineer recommending 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 if the inspection is performed, and the report written, by an Engineer meeting the requirements of Rule 4.10. The Owner's Engineer shall notify the State Engineer at least fourteen (14) days prior to the scheduled safety inspection. Inspections shall be conducted in accordance with current State Engineer policies and these Rules.
12.2 Scope of Inspection. Dam safety inspections by the Owner's Engineer shall meet the requirements of Rule 4.31. The Engineer shall prepare an inspection report that describes the findings and lists actions the Owner must take to improve the safety of the dam to an acceptable level. The report shall provide the information necessary to allow the State Engineer to make a determination of the safe storage level of the reservoir.
12.3 State Engineer Acceptance. The report will be reviewed by the State Engineer prior to acceptance. If the report and findings are accepted, the State Engineer will provide the Owner with a list of required actions and will notify the Owner of the safe storage level. Rule 13. Owner's Responsibilities 13.1 Liability. The sole responsibility for the safety of the dam rests with the Owner, who should take every step necessary to prevent damages caused by leakage or overflow of waters from the reservoir or floods resulting from a failure of the dam. Therefore, it is in the Owner’s best interest to operate and maintain the facility in a manner such that the safety of the dam and the general public are not jeopardized.
13.2 Change in Ownership. Changes in ownership of a dam shall be immediately filed with the State Engineer.
13.3 Site Security. The Owner shall maintain reasonable security measures to prevent intentional misoperation and damage to the facility.
13.4 Dam Observation and Monitoring Plans. All dams shall have an observation and monitoring plan that shall include the following minimum requirements:
13.4.1 Owner Observations. The Owner is responsible for ensuring frequent observation of the dam, especially at times when the reservoir is full, during heavy rains or flooding, and following an earthquake. The observations shall be conducted in accordance with methods acceptable to the State Engineer. Conditions which threaten the safety of the dam shall be reported to the State Engineer immediately.
13.4.1.1 High and Significant Hazard dams shall be observed at least twice a
13.4.1.2 Low Hazard dams shall be observed at least once every three months.
13.4.1.3 For all dams, routine outlet observations shall include observation of
13.4.2 Monitoring Instrumentation. The Owner is responsible for installing, maintaining, and monitoring the instrumentation required to adequately monitor the performance of the dam. The instrumentation shall be monitored at a frequency detailed in the approved observation and monitoring plan.
13.4.2.1 Monument surveys accurate to 0.01 foot are required annually for five
13.4.2.2 The Owner is responsible for ensuring that all instrumentation data is
13.4.2.3 The Owner shall promptly notify the State Engineer of any abnormal
13.5 Outlet Operation. The Owner shall maintain the outlet works in an operable condition.
13.5.1 Outlet Inspections. The requirements of outlet inspections are as follows:
13.5.1.1 Outlet Exercise. An annual test of the outlet gate(s) and valve(s) for
13.5.1.2 Outlet Inspection Access. Outlet structures for all dams will be
13.5.1.3 Internal Outlet Inspections. Internal outlet inspections shall consist of a close inspection of the interior of the conduits, outlet wells, and access ways. In cases where it is unsafe or not possible for a person to enter, the Owner shall provide for an inspection using video or other remote sensing equipment capable of detecting flaws or imperfections within the conduit. An Engineer shall oversee the inspection and provide a written report of inspection findings to the State Engineer. The State Engineer shall coordinate with the Owner and make all reasonable efforts to minimize expense and waste of water while ensuring dam safety.
13.6 Responsibility for Maintenance. The Owner is responsible for adequate and timely maintenance of the dam. The Owner shall establish a maintenance plan to ensure that the maintenance, as identified in Rule 11, is accomplished.
13.7 Emergency Preparedness. Owners shall be prepared to take emergency actions to prevent unusual or emergency situations at their dams from escalating to dam failure. To the extent possible, Owners shall also make preparations to reduce the consequences of potentially dangerous reservoir releases when such releases are unavoidable or necessary.
13.7.1 Emergency Action Plans (EAP). An EAP shall be developed and distributed by the Owner for all High and Significant Hazard dams. The EAP shall contain the following information, at a minimum:
13.7.1.1 Essential Dam Information. This section shall include a description of
13.7.1.2 Event Level Determination and Expected Actions. This section shall
13.7.1.3 Notifications. This section shall include a list of all members of the
13.7.1.4 Communication. This section shall include a description of how
13.7.1.5 Locally Available Resources. This section shall identify locally
13.7.1.6 Evacuation Information. This section shall present information provided to aid the emergency response team with the evacuation of the inundation zone below the dam. The following information shall be included, at a minimum:
13.7.2 Termination. The responsibilities for termination of an EAP activation shall be described.
13.7.3 EAP Distribution. The Owner shall submit an electronic copy of the EAP to all members of the emergency response team as shown on the notification list.
13.7.4 EAP Updates. The Owner shall review the EAP annually and update as necessary and appropriate. EAP updates shall be included in a single PDF containing the complete EAP and distributed electronically to all emergency response team members shown on the notification list.
13.7.5 EAP Testing. The Owner shall test the EAP periodically to ensure the effectiveness of the EAP. The contact information shown in the notification list shall be reviewed annually to ensure it is up to date, and to obtain information for revisions or corrections as necessary.
Rule 14. Exempt Structures 14.1 Exempt Structures. See section 37-87-114.5, C.R.S., with the following clarifications:
14.1.1 Highways, road-fills, and railroad embankments with ungated culverts are exempt.
14.1.2 Structures that store water only below the lowest point of the natural ground are exempt from these Rules, unless an outlet works is constructed to release water.
14.2 Livestock Water Tanks. Livestock Water Tanks as defined in the Livestock Water Tank Act of Colorado, Title 35, Article 49, C.R.S., are exempt from these Rules.
14.3 Erosion Control Dams. Erosion Control Dams, as defined in section 37-87-122, C.R.S., are exempt from these Rules.
14.4 Dams or other water impounding structures regulated by other State agencies (e.g. COGCC, CDPHE, DRMS, etc.) may be exempt from these Rules to avoid dual regulation. The State Engineer may provide technical consultation as necessary for the permitting of such structures. Rule 15. Restriction of Recreational Facilities within Reservoirs 15.1 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 crest of the spillway unless:
A. The facility is capable of being restored with a minimum amount of cleaning or expense, and either, B. The facility is constructed to withstand partial or complete inundation with minimal or no damage, or C. The facility is necessary to the operation of the reservoir.
15.2 Notice. Any person planning to construct, enlarge, or modify any facility under this Rule shall provide written notice to the State Engineer at least one hundred eighty (180) days in advance of construction. State Engineer approval shall be obtained prior to construction.
15.3 Exemptions. Exemptions to this Rule include the following:
A. Facilities completed prior to July 1, 1984, excluding subsequent enlargements or modifications to such facilities.
B. Boat ramps, Docks, and Marinas are exempt from the notice and approval requirements of Rule 15.2.
Rule 16. 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 Owners under the foregoing Rules if, in the State Engineer’s judgment, dam safety will not be reasonably impaired and the circumstances of the individual case so warrant. The State Engineer’s decision will take into account the benefits that 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 to beneficial use of water in Colorado.
Rule 17. Appeal of Requirements or Approval The applicant or any other person affected or aggrieved by the State Engineer's approval or disapproval of plans and specifications for construction of a reservoir/dam, or the alteration, modification, repair or enlargement of a reservoir or dam which will affect the safety of the structure may request an adjudicatory hearing before the State Engineer pursuant to Rule 10(4)(c) of the Division of Water Resources' Procedural Regulations, 2 CCR 402-5. All adjudicatory hearings will be conducted pursuant to the requirements of the Division of Water Resources' Procedural Regulations and the State Administrative Procedure Act, section 24-4-105, C.R.S.
Rule 18. Rules by 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 State Publications Depository and Distribution Center, and shall be available for public inspection during business hours. The title and address of the Office of the State Engineer is: 1313 Sherman Street, Room 818, Denver, CO 80203. Materials incorporated by reference do not include any later amendments or editions to those materials. Rule 19. 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 20. 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 Rule 7.B.2 of the Division of Water Resources’ Procedural Regulations, 2 C.C.R. 402-5. Rule 21. Statement of Basis and Purpose Incorporated by Reference The Statement of Basis and Purpose for the adoption of these Rules and Regulations for Dam Safety and Dam Construction is incorporated by reference as part of these Rules. Rule 22. Effective Date These Rules shall become effective on January 1, 2020.
_________________________________________________________________________ Editor’s Notes History Entire rule eff. 01/01/2020.