Or. Admin. Code § 690-020-0140 - Modification of Dams

(1) No person shall make Modifications to a Dam unless the State Engineer has reviewed all required documents as described in this section and has approved those documents as indicated in written communication with the Engineer of Record or Dam owner.

(2) The following Dam Modifications require State Engineer approval of plans:

(a) Changes to or near the Spillway that may affect Spillway capacity or ability to pass flows safely;

(b) Placing, replacing, or relining any Conduit within the Dam;

(c) Removal or alteration of the Conduit control structure;

(d) Installation of a new Valve on the downstream side of the low level Conduit;

(e) Correction of damage where that damage has impacted the safe functioning of the Dam;

(f) Any activity where 10 percent or more of the fill material in the Dam is disturbed; or

(g) Any other change to the Dam that results in a Modification as defined in OAR 690-020-0022(28).

(3) Dam Modification plans shall include all details of the area of the Dam being modified. Specific modification plan requirements include, but are not limited to:

(a) For major Spillway damage or alteration, plans need to address passage of the required Inflow Design Flood based on the Hazard Rating of the Dam, with the same criteria as required for new Dams in OAR 690-020-0037;

(b) For stabilization of slope movement, plans require slope stability analysis and appropriate corrective measures;

(c) For replacement of Conduits or installation of a Valve on the downstream side of a Dam, plans require an analysis of internal erosion potential;

(d) For internal erosion, plans must address construction of a filter zone; and

(e) Items required by the State Engineer pursuant to subsection (4).

(4) The Dam owner shall provide sufficient notice to the Department to allow for adequate time for discussion of the proposed Modifications and the necessary design requirements.

(5) The State Engineer will determine the design and submittal requirements. Submittal requirements and Department reviews may be expedited in the event of emergency or unanticipated weather-related situations.

(6) Water is not to be stored in the reservoir during modification. The Engineer of Record may propose maintaining some Water in storage during Dam Modification or modifying Dam Height if it is demonstrated that it can be done in a manner that protects life, property, and infrastructure. The Department will review submitted materials for the proposed construction actions. The Department may consider the scope of the project, including how the proposed construction actions will maintain safe Water levels through the duration of construction.

Notes

Or. Admin. Code § 690-020-0140

WRD 3-2020, adopt filed 06/29/2020, effective 7/1/2020

Statutory/Other Authority: ORS 536.027, 540.488

Statutes/Other Implemented: ORS 540.443, 540.449, 540.488