The U.S. Army Corps of Engineers, Nashville District has prepared a Draft Environmental Assessment (EA) and unsigned Finding of No Significant Impact (FONSI) under the National Environmental Policy Act (NEPA) of 1969, as amended, for proposed work at Center Hill Dam in DeKalb County, Tennessee (enclosed map). The purpose of the EA is to evaluate potential effects of the proposed replacement of the spillway tainter gates and lifting equipment and implementation of a risk reduction measure.
The EA evaluates both the No Action Alternative and the Proposed Action Alternative (PAA). The PAA is the tentatively selected plan and appears to not cause significant adverse effects on the quality of the human environment; therefore, preparation of an Environmental Impact Statement would not be required. The considered alternatives are as follows:
• No Action Alternative: Repair/Replace spillway gates as they fail within the constraints of normal operation and maintenance timing and budget.
• Proposed Action Alternative – Replace Spillway Gates: Replace all eight spillway gates at Center Hill Dam over four years at the anticipated rate of up to two gates per year. It would be anticipated that up to three gates would be inoperable year-round with only one gate bay open at a time and only during the gate replacement window of June to November. The following would be included in replacing the gates:
1. Remove existing gates and replace with similar gates. New member sizes would be slightly larger.
2. Remove existing lifting machinery and replace machinery base with equipment layout similar to that of the existing equipment. New lifting equipment would be stronger to raise the new heavier gates. In addition, the chain lifting system would be replaced with rope hoist system and the electric layout would be modified to accommodate the new equipment.
3. Use of an existing disturbed area adjacent to the Auxiliary Dam on the right descending bank of Center Hill Dam for a construction laydown/staging area.
4. Remove trees along an existing launch ramp, modification of the existing launch ramp to facilitate launching heavier equipment; tree removal would be minimal, and the vegetation would be mulched not burned.
5. Install temporary work platforms on top of the dam, associated work includes drilling anchor holes and epoxying anchors into concrete.
6. Implement lead abatement measures related to the partial removal of existing gate components
7. Use of a floating plant (work barge) with crane.
8. Restrict traffic on Cove Hollow Road (Highway 96) to one lane for the duration of each construction season (approximately 5 months) and occasional full closure up to 24 hours, not on the weekends.
9. Follow the Optimum Curve within the Southeastern Power Administration (SEPA) Power Marketing Band, as described below to reduce risk during construction.
The EA evaluates environmental effects of the PAA and the no action alternative under the following categories: Recreation, Scenic Resources, and Noise; Water Quality and Aquatic Resources; Flood Risk Management; Climate and Physiography; Terrestrial Resources; Federally Listed Species; Cultural Resources; Hazardous; Toxic; and Radioactive Waste; Health and Safety; Socioeconomics; and Air Quality.
This letter serves as a Notice of Availability for reviewing the draft EA and unsigned FONSI. The draft EA is prepared pursuant to the National Environmental Policy Act (NEPA) (42 U.S.C. §§ 4321-4370h), Council on Environmental Quality Regulations (40 C.F.R. §§ 1500-1508), and the Corps' implementing regulation, ER 200-2-2, 1988 (33 C.F.R. § 230), Policies and Procedures for Implementing NEPA. Electronic copies of the documents can be found at: https://www.lrn.usace.army.mil/Media/Public-Notices/Category/10561/project-planning-branch/.
We request comments be sent by email to CorpsLRNPlanningPublicCom@usace.army.mil no later than thirty calendar days from the date of this letter to ensure consideration in the final EA. If you are unable to access an email account, you may send written comments to the address listed on the letterhead, ATTN: CELRN-PMP (Chip Hall). Your participation is greatly appreciated. For additional information regarding the proposed project, please contact Chip Hall at 615-736-7666.