Current through October 22, 2024
Section 0400-45-07-.06 - STANDARDS FOR EXISTING DAMS(1) Stability. All dams shall be stable. There shall not be excessive cracks, sloughing, seepage or other signs of instability or deterioration. In cases where the stability of the dam is questionable, it shall be the responsibility of the owner to either demonstrate to the Commissioner that the dam is stable or drain the reservoir and remedy the unstable condition prior to refilling the reservoir.(2) Slope Protection (a) Earth embankments shall be protected from surface erosion by appropriate vegetation or some other type protective surface such as riprap or paving and shall be maintained. Examples of appropriate vegetation include, but are not limited to, Bermuda grass and fescue. All inappropriate vegetation such as honeysuckle, briers, bushes, and trees shall be removed from the dam. Some trees may be allowed to remain on a dam if the Commissioner concurs with a justification from a qualified engineer for doing so. Such justification must satisfy the Commissioner that the number, size, location, root characteristics, etc., of such trees will not adversely affect the dam's structural integrity and safety nor impede inspection.(b) The root mass of all trees larger than four (4) inches in diameter as measured at two feet above ground level shall be grubbed out and the hole backfilled with suitable fill material properly compacted. Smaller trees may either be cut at ground level or be removed as specified above. The Commissioner may require an engineer to oversee the tree removal.(3) Emergency Spillway.(a) All dams shall have an emergency spillway system with capacity to pass a flow resulting from a 6 hour design storm indicated in subparagraph (b) of this paragraph for a hazard classification appropriate for the dam. However, if the applicant's engineer provides calculations, designs, and plans to show that the design flow can be stored, passed through, or passed over the dam without failure occurring, or if he can successfully demonstrate to the Commissioner by engineering analysis that the dam is a safe structure and can certify that the dam is sufficient to protect against probable loss of human life downstream, said dam design may be approved by the Commissioner.(b) Minimum Freeboard Design Storms. Hazard Potential Category | Size | Freeboard Design Storm (6 Hours) |
Category 3 (Low) | Small Intermediate Large | 100 year 1/3 PMP 1/2 PMP |
Category 2 (Significant) | Small Intermediate Large | 1/3 PMP 1/2 PMP PMP |
Category 1 (High) | Small Intermediate Large | 1/2 PMP PMP PMP |
(c) No dam which is modified after original construction to increase its design storm to a 1/2 PMP or greater shall be required to pass a larger design storm unless the dam itself is enlarged or its normal or maximum storage volume is increased.(4) Concrete and Masonry Dams. Concrete and/or masonry dams shall be structurally sound and shall have joints free of trees and other vegetation and shall show no signs of significant structural deterioration such as excessive cracks, spallation, efflorescence and exposed reinforcing steel.Tenn. Comp. R. & Regs. 0400-45-07-.06
Original rule filed October 16, 2012; effective January 14, 2013. Rule renumbered from 1200-05-07.Authority: T.C.A. §§ 69-11-101 et seq., and 4-5-201 et seq.