2 CCR 402-1-9 - 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:

9.1.3.6.1 The plan shall be prepared by an Engineer.

9.1.3.6.2 The breach shall be of sufficient width to pass the twenty four (24) hour, one percent AEP flood with a maximum increase in reservoir depth of five (5) feet. However, the maximum breach width shall not be required to exceed the width of the original natural channel before the dam was constructed, regardless of the one percent AEP flood.

9.1.3.6.3 Breach side slope and channel protection may be required to prevent erosion and provide long-term stability.

9.1.3.6.4 Remaining infrastructure shall be left in a safe condition.

9.1.3.6.5 Construction plans shall meet the requirements of Rule 6 that are applicable to support the scope of work as described on the application.

9.1.3.6.6 The dewatering and removal or breaching of the dam shall be overseen by an Engineer.

9.1.3.6.7 A written notification that the project is complete and in general conformance with the approved breach plan shall be provided within sixty (60) days of completion of construction. The State Engineer will provide acceptance upon review and receipt of these documents.

Notes

2 CCR 402-1-9

42 CR 23, December 10, 2019, effective 1/1/2020