OAR 690-020-0120
Dam Breach Inundation Analysis

(1)

A Dam breach inundation analysis will be conducted as specified in this section to determine or revise the Hazard Rating of a Dam.

(2)

Any simplified and conservative hydraulic model may be used for the Dam breach inundation analysis to show that a Dam should be rated Low Hazard. The State Engineer may determine if the model was used appropriately and conservatively.

(3)

An accepted and hydraulically consistent computational model must be used to conduct the inundation analysis for Significant and High Hazard Dams.

(4)

A report summarizing the model information and results must be stamped by the Engineer. The summary report shall contain sufficient information to reproduce the model and shall include at a minimum the following information:

(a)

The specific proprietary model name or method used for the analysis;

(b)

Details regarding the model geometry;

(c)

The specific mode of failure and any assumptions made in the selection of the mode of failure;

(d)

A list of Dam breach parameters and any assumptions made in the selection of the breach parameters. The breach parameters must be based on Dam material and thickness and any other factors that would influence the time it would take for the Dam to breach from internal erosion, overtopping, or displacement;

(e)

A list of all boundary and initial conditions and any assumptions in the selection of these conditions. For High and Significant Hazard Dams, the analysis must be conducted with reservoir at full pool and inflow equal to the 0.2% Annual Exceedance Probability Flood flow;

(f)

A map indicating the inundation boundary, areas inundated by a depth greater than two feet, and all frequently occupied structures that fall within or are immediately adjacent to the inundation boundary;

(g)

The breach flow as calculated by the model immediately downstream of the Dam. If an empirical formula was used as the basis for determining breach flow, the formula and all inputs must be clearly stated; and

(h)

A sensitivity analysis evaluating the variability in model inputs may be required when the Dam breach inundation analysis results indicate the Hazard Rating is on the border between two ratings.

Source: Rule 690-020-0120 — Dam Breach Inundation Analysis, https://secure.­sos.­state.­or.­us/oard/view.­action?ruleNumber=690-020-0120.

690‑020‑0000
Purpose and Applicability 690‑020‑0022
Definitions 690‑020‑0024
General Department Authorities and Intergovernmental Coordination 690‑020‑0026
Fees 690‑020‑0028
Preliminary Plans and Specifications for Construction of New Dams or to Increase Dam Height 690‑020‑0035
Minimum Engineering Requirements for Final Design of New Dams or to Increase Dam Height 690‑020‑0036
Design Requirements for New Dams or to Increase Dam Height: Site Suitability and Geotechnical Evaluation 690‑020‑0037
Design Requirements for New Dams or to Increase Dam Height: Hydrology and Inflow Design Flood 690‑020‑0038
Design Requirements for New Dams or to Increase Dam Height: Embankment Dam Structures 690‑020‑0041
Design Requirements for New Dams or to Increase Dam Height: Concrete Dam Structures 690‑020‑0042
Minimum Design Requirements for New Dams or to Increase Dam Height: Spillways 690‑020‑0043
Design Requirements for New Dams or to Increase Dam Height: Penetrating Conduit(s) and Control of Flow through Conduits 690‑020‑0044
Design Requirements for New Dams or to Increase Dam Height: Instrumentation for Monitoring 690‑020‑0047
Design Requirements for New Dams or to Increase Dam Height: Geosynthetics 690‑020‑0048
Exceptions to Standard Design Requirements 690‑020‑0055
Design Requirements for New Dams or to Increase Dam Height: Design Drawings 690‑020‑0060
Design Requirements for New Dams or to Increase Dam Height: Construction Specifications 690‑020‑0065
Plan Requirements for New Dams or to Increase Dam Height: Construction Administration 690‑020‑0068
Plan Requirements for New Dams or to Increase Dam Height: Operations and Maintenance Plan 690‑020‑0070
New Dams or to Increase Dam Height: Submittals and Notifications by the Engineer of Record 690‑020‑0080
New Dams, or to Increase Dam Height, Written Approval by State Engineer 690‑020‑0100
Hazard Rating of Dams 690‑020‑0120
Dam Breach Inundation Analysis 690‑020‑0140
Modification of Dams 690‑020‑0160
Removal 690‑020‑0180
Requirement of Owners to Provide Contact and Transfer of Title Information 690‑020‑0250
Maintenance of Dams 690‑020‑0260
Inspection of Dams 690‑020‑0310
Requirement to Address Maintenance Actions Need for High or Significant Hazard Dams 690‑020‑0340
Potentially Unsafe or Unsafe Conditions 690‑020‑0400
Emergency Action Plans (EAP) 690‑020‑0420
Immediate Action to Prevent Dam Failure 690‑020‑0460
Proposed Final Order, Request for Hearing, Contested Case Process 690‑020‑0600
Civil Penalty Assessment for Dam Safety
Last Updated

Jun. 8, 2021

Rule 690-020-0120’s source at or​.us