OAR 690-020-0043
Design Requirements for New Dams or to Increase Dam Height: Penetrating Conduit(s) and Control of Flow through Conduits

New Dams on stream channels must have a low level Conduit. All other new Dams and Dams with increases to Dam Height must have a low level Conduit or other means to safely drain the reservoir. The Conduit and related control structures must be designed to meet the following criteria:

(1)

Ability to lower the reservoir. The minimum diameter of the Conduit should be determined through analysis of the time required to drain the Dam at average annual inflow;

(a)

The Conduits for High Hazard Dams shall be capable of releasing the amount of Water which could be stored in the top five feet of the reservoir in five days;

(b)

The Conduits for Significant and Low Hazard Dams must be able to release the amount of Water which could be stored in the top five feet of the reservoir in ten days;

(c)

All Conduits must be of sufficient size to allow passage of inflows as needed;

(d)

In no case shall Conduits be smaller than eight inches in diameter;

(2)

Durable and water-tight Conduits. Conduits must be made of medium to heavy gage durable materials. Pipe joints must be designed to seal and prevent leakage. Corrugated metal culverts are only acceptable for Low Hazard Dams, and only when the Conduits are encased in concrete. Encasement of Conduits in concrete may be used to assist in the design of a durable Conduit and to reduce the potential for seepage and erosion adjacent to the Conduit;

(a)

Diaphragms using materials designed as an effective Soil Filter are required for any Conduits not designed as encased in concrete, and are required regardless of encasement for all High Hazard Dams;

(b)

Seepage collars may not be used;

(3)

Control Mechanisms. The design for the control mechanism must be sturdy and durable. The control mechanism must allow for air venting when needed, and allow manual operation to drain the reservoir if hydraulic or other power controls are inoperable. Hydraulic or other power controls must have redundancy if control relies on any submerged hydraulic or pneumatic hoses or electrical conduits. Intake structures for outlet works must have trash racks unless the Engineer of Record shows trash racks are unnecessary, or not safe to construct due to conditions at the Dam site. For High and Significant Hazard Dams, measures to prevent unauthorized use of the control mechanism must be included in this design;

(4)

Outlet structure. The outlet structure must not be submerged when the inlet control Gate or Valve is fully closed. The outlet structure must be designed to protect the Conduit from mechanical damage and convey Water to the stream channel without channel erosion and cavitation near the Gate structure; and

(5)

Pressurized operation. Conduits must be specified as suitable for pressurized operation if they are to be operated with controls other than at the inlet of the Conduit. Dams with Pressurized Conduits shall have a guard Gate installed at the upstream end of the Conduit. Operations and maintenance plans are required for any Dam designed for pressurized operation as per OAR 690-020-0068 (Plan Requirements for New Dams or to Increase Dam Height: Operations and Maintenance Plan).

Source: Rule 690-020-0043 — Design Requirements for New Dams or to Increase Dam Height: Penetrating Conduit(s) and Control of Flow through Conduits, https://secure.­sos.­state.­or.­us/oard/view.­action?ruleNumber=690-020-0043.

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 690-020-0043’s source at or​.us