Or. Admin. R. 690-020-0060

Current through Register Vol. 63, No. 6, June 1, 2024

Section 690-020-0060 - Design Requirements for New Dams or to Increase Dam Height: Construction Specifications

All drawings for Dams must be accompanied by construction and material specifications that include the following:

(1) Construction conditions. Specifications must include the construction period based on typical weather and stream conditions for that location and if applicable, may include a process for the Engineer of Record to modify the construction period;

(2) Clearing of the Dam site and reservoir. Specifications must include the area to be submerged by the new or enlarged reservoir and specify that the submerged area shall be cleared of logs and debris prior to filling the reservoir. The specifications must require that the footprint of the Dam shall be cleared of all soils containing organic materials, and that this material may not be used for Dam construction;

(3) Cutoff Trench requirements. Specifications must include the minimum trench depth, width at base of the trench, and maximum side slope steepness. These specifications shall be based on the subsurface investigations and direct that the Cutoff Trench may not be filled if it contains standing Water. Specifications must also include a requirement not to begin filling the Cutoff Trench until approved by Engineer of Record, and where specified, approved by the Department;

(4) Material specification standards. The specifications shall include material and testing specifications for Dam materials, Conduits, control structures, and other appurtenant structures, using an ASTM standard methodology if available;

(5) Soil Compaction. The typical compaction specification is 95 percent of standard proctor density, though the Engineer of Record may use a different compaction standard. Specifications shall include the types of acceptable compaction equipment, by material source if necessary. Specifications shall also include maximum lift thickness. Specifications shall prohibit soil compaction dry of optimum moisture content to reduce potential for leakage around the Conduit. For materials placed immediately above or adjacent to the Conduit, specifications must also include verification testing of soils, with representative samples selected for testing as directed by the Engineer of Record. Specifications must also require verification of testing of soil compaction, with representative samples selected for testing by the Engineer of Record, or Engineer's representative;

(6) Concrete placement. Specifications shall include means to prevent separation of aggregate and cement, air entrainment requirements if needed, methods for placement and vibration of concrete, required minimum 28 day strength, slump, moisture and temperature requirements for curing. Alkali reactive aggregate shall not be used in the concrete;

(7) Conduit specifications. Specifications must include the material, diameter, and thickness of the Conduit, and the length of Conduit required for the project. Methods for sealing joints must be specific. Specifications must require that all materials from a manufacturer are certified to meet this test, or that the Engineer of Record has tested the materials directly;

(8) Accepting and Rejecting Materials. Specifications must include tolerances for acceptable departure from material specifications and a process for rejection of defective materials or workmanship;

(9) Notification by the Engineer of Record to the State Engineer of changed conditions critical to the safety or operations of the Dam. Specifications shall include State Engineer notification if previously unidentified springs, slope movement or sand lenses are identified, or if storm or other damage occurs during construction;

(10) The Engineer of Record or their qualified employees must supervise construction as needed to assure compliance with the approved construction plans and specifications; and

(11) The specifications must also contain a provision to the effect that plans or specifications shall not be altered or changed without the written approval of the State Engineer.

Or. Admin. R. 690-020-0060

WRD 2-2015, f. & cert. ef. 3/17/2015; WRD 3-2020, amend filed 06/29/2020, effective 7/1/2020

Statutory/Other Authority: ORS 536.027, 540.488

Statutes/Other Implemented: ORS 540.449, 540.488