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Dam Safety Office Engineering Guidelines and Technical Notes

Owners are required to develop an Operation and Maintenance Manual for their project and submit it to the Dam Safety Office for their acceptance.  If the project is located above a populated area, then an Emergency Action Plan (EAP) must also be prepared and submitted.

The following are Examples O&M and EAP documents:

• Guidelines for Developing Emergency Action Plans (1.3MB pdf)
• Guidelines for Developing Dam Operation and Maintenance Manuals (5.2MB pdf)
• Dam Owner's Annual Inspection Form (237kb pdf)
• Simple O&M Document (17.5kb pdf)
• Simple EAP Document (45.0kb pdf)

Dam Safety Guidelines and Technical Notes

To order a printed copy of any of the guidelines or technical notes described below, contact us via mail or e-mail.

Each year the Dam Safety Office develops a Report to the State Legislature that describes the dams in the state with safety deficiencies and progress towards correcting these deficiencies. The report also lists the dam owner and the estimated cost of repair for each dam. This report is available upon request.

The Dam Safety Guidelines are intended to provide dam owners, operators, and design engineers with information on activities, procedures, and requirements involved in the planning, design, construction, operation and maintenance of dams in the State of Washington.

For convenience of the various expected users, the guidelines have been organized into four basic units entitled:

• Part I, General Information and Owner Responsibilities: Contains general information about statutory authority, dam safety activities, and dam owner responsibilities for completed projects.
• Part II, Project Planning and Approval of Dam Construction or Modification: Provides information on the specific activities and actions that are involved in project planning and the plan review and construction permit process. An overview of the planning process is provided along with a list of permits and approvals that are normally involved.
• Part III, An Owner's Guidance Manual: Is a reference manual for dam owners to use in developing plans for operation, monitoring, annual inspection and long term maintenance of their facilities. The manual was prepared by the Association of State Dam Safety Officials (ASDSO) and the Federal Emergency Management Agency (FEMA).
• Part IV, Dam Design and Construction: Engineering Design Guidelines address frequently encountered engineering issues as they affect a broad range of project types.  The principal focus of this document is the earthen dam of small to intermediate size, which represents the majority of the projects constructed in Washington State.

  Hydraulic computations for open spillways and riprap-lined channels - these Microsoft Excel spreadsheets include stage-discharge curve for the spillway, drawdown from critical flow to supercritical uniform flow in steep channels, and stability calculations for loose riprap.  Template spreadsheets and worked examples are provided, along with a separate set of instructions and tips (Instruct.doc) for using the spreadsheets.  We recommend reading Instruct.doc before getting into the spreadsheets.

  • Self-extracting file that contains these spreadsheets and document (288kb)

  Hydraulic computations for Drop Inlet Spillways - these Microsoft Excel spreadsheets included stage-discharge curve for the spillway, flow surges and pressure fluctuations in the outlet pipe, and downstream tailwater conditions.  Template spreadsheets and worked examples are provided, along with a separate set of instructions and tips (Instruct.doc) for using the spreadsheets. We recommend reading Instruct.doc before getting into the spreadsheets.  

  • Self-extracting file that contains these spreadsheets and documents (1.3MB)

  Guidance for design details for conduits through earth embankments and for air vents for drop inlet spillways.

  • Dam conduits.pdf (2.2 MB pdf)
  • Dam airvents.pdf (2.4 MB pdf)

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  Engineering Technical Notes

  Technical Note 1: Dam Break Inundation Analysis and Downstream Hazard Classification Provides assistance in conducting a Dam Break Inundation Analysis and in assessing the downstream hazard posed by a dam failure.

  Dam breach calculations using the equations from Technical Note 1 - Microsoft Excel spreadsheets include calculations for both the dam breach hydrograph and downstream routing of the dam breach flood. Template spreadsheets and worked examples are provided, in both metric and U.S. customary units, along with a separate set of instructions and tips (Instruct.doc) for using the spreadsheets.    

  • Self-extracting file that contains these spreadsheets and documents (481kb)

  Technical Note 2: Selection of Design Performance Goals for Critical Project Elements: Critical Project Elements of a project are those elements of a project whose failure could result in dam failure and an uncontrolled release of the reservoir. This technical note provides guidance in selecting design/performance goals for critical project elements. It has application in design of proposed dams and in evaluating the adequacy of existing dams.

  Technical Note 3: Design Storm Construction: Provides engineering guidance for development of design storms for use in computing Inflow Design Floods using rainfall-runoff computer models for spillway design.

  Download the following four figures that are to be included in Appendix A:  

  • Figure A1 (1.6MB pdf)  
  • Figure A2 (1.3MB pdf)  
  • Figure A3 (1.3MB pdf)  
  • Figure A4 (1.2MB pdf)

  The following maps are excerpted and adapted from HMR-57 (NWS, 1994) for 1-hour and 24-hour PMP:

  • PMP 1-hr (70kb pdf)
  • PMP 24-hr (267kb pdf)

  Inflow Design Flood computations following the procedures of Technical Notes 2 and 3 - Microsoft Excel spreadsheets and hydrographs along with brief instructions (file named Instruct.doc) to supplement the information provided in the Technical Notes.

  • Self-extracting file that contains these spreadsheets and document. (213k)

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