Environmental Assessment - Tennessee Valley Authority

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measures associated with the Action Alternative, impacts to aquatic organisms and water quality from disturbance or modification of adjacent land and the riverbed would be minimized. Water Withdrawal For LUB to meet increasing water demands, the treatment plant and intake structure will need to be expanded from the current capacity of 14 to 20 MGD. While the existing raw water intake has sufficient capacity to supply 22 MGD to the plant, the intake does not provide adequate firm pumping capacity for the expanded plant capacity of 20 MGD. Jordan, Jones & Goulding, engineering consultants for LUB (see Attachment A), provided historic and projected water demand from 2005 to 2020. This demand was categorized as minimum day, average day, and peak day demand. Analyses of the 2009 demand projections indicated that average day demand would be approximately 80 percent of capacity and would likely exceed plant capacity by 2015. Analyses also indicated that peak day demand would likely exceed plant capacity during 2010. No Action Alternative - If TVA adopts the No Action Alternative, the volume of water withdrawn from the Tennessee River by LUB would not be increased. There would be no effect on water withdrawal. If the existing treatment plant and intake structure capacities are not expanded, water demand would exceed capacity over the next few years, and LUB would not be able to meet customer demand. Action Alternative With Modification - The Action Alternative is to construct a new raw water intake structure and piping to support expansion of the WTP. This new intake structure would increase Loudon Utilities’ pumping capacity from 14 MGD to 20 MGD. An analysis of increased water withdrawal was conducted to determine the following: • Whether the withdrawal increase would adversely impact downstream municipal/industrial water supplies • Whether the water intake structure was at a sufficient depth to prevent operational impacts during low flows • Whether the water withdrawal increase aligned with forecasted customer water demand in the future Two industrial water intake facilities are immediately downstream of LUB’s proposed water intake structure. Viskase Corporation (TRM 591.7) withdraws approximately 1.5 MGD, while Kimberly Clark Corporation (TRM 589.9) withdraws approximately 5.0 MGD. Because of flows in the river at these locations (approximately 9,000 MGD average flow and 1,265 MGD on lowest-flow day of 2007, which was the driest year of record), increasing Loudon Utilities’ withdrawal from 14 MGD to 20 MGD represents only 0.07 percent of the average flow, or 0.5 percent of the 2007 low-flow day. This degree of increase in withdrawals should have no adverse effect on downstream municipal/industrial water withdrawals by others. The proposed water intake structure would have a top-of-screen elevation of no higher than 721 feet msl. Maximum drawdown elevation for Watts Bar Reservoir is 733 feet msl, leaving at least 12 feet of water over the top of the intake structure. This would likely ensure continuous operation during normal low water elevations in the reservoir. 14
The proposed intake would be located in the Tennessee River below Fort Loudoun Dam. TVA operates its system of dams and reservoirs according to an operational policy adopted in 2004. This policy is based upon meeting future consumptive use above Fort Loudoun Dam of 241 MGD (Bohac and Koroa, 2004, Tables 2-1 and 3-1). The consumptive use above Fort Loudoun Dam in 2005 was 143 MGD (Bohac and McCall, 2008, Table 2-1). The consumptive use increase for the additional 6 MGD peak withdrawal is 1.37 MGD or approximately 0.9 MGD for average withdrawal (based on the consumptive use in Loudon County of approximately 23 percent; see Bohac and McCall, 2008, Table 2-3). Therefore, the proposed increase in withdrawal would be within the limits of TVA’s modeling of water withdrawals and returns developed for its Reservoir Operations Policy. Cumulative Impacts Resources that could cumulatively be affected by the new water intake and pipeline are aquatic ecology, water quality, and aquatic threatened and endangered species. The Action Alternative would result in a loss of individual pick mucket mussels and snail darters in the project area. However, this action would not result in cumulative impacts to these species on a regional or Valleywide basis because of the existence of other populations. Water quality would continue to be affected by general population, industrial use, and lakefront development growth in the area. In order to avoid contributing to degradation of aquatic ecology and water quality in the area, TVA would require use of erosion-control measures during construction of the water intake and pipeline. Although it would have a somewhat greater impact than the No Action Alternative, the Action Alternative would result in a minimal impact on the environment and improve availability of local potable water supply when the proposal was completed. Therefore, TVA has determined that cumulative impacts of this action would be insignificant. Necessary Permits and Public Involvement Approval under Section 26a of the TVA Act of 1933, as amended, is required for the construction of any obstructions in and along the Tennessee River or its tributaries. The proposal would also require approval by USACE under Section 10 of the Rivers and Harbors Act and Section 404 of the Clean Water Act. Pursuant to Section 401 of the Clean Water Act, on September 2, 2009, a Water Quality Certification/Aquatic Resources Alteration Permit (ARAP) was issued for both the water intake and the pipeline crossing of the Tennessee River by TDEC’s Division of Water Pollution Control. The proposed action was the subject of Public Notice 09-51 issued by USACE on June 24, 2009, for a 30-day public comment period. The comments received during this period, along with a copy of the joint public notice, are located in Attachment F of the EA. In a letter to USACE dated July 17, 2009, the USFWS identified the following species as possibly occurring in the immediate vicinity of the proposed project: the endangered pink mucket (Lampsilis abrupta) and orange-foot pimpleback (Plethobasus cooperianus) and the threatened snail darter (Percina tanasi). TWRA identified the same three species as potentially being impacted by the project in a July 23, 2009, letter. In a June 30, 2010, letter to USACE and TVA, the USFWS provided a BO to the BA prepared under USACE direction. Following a modification of plans to lower the depth of the river crossing and water intake, USACE prepared a revised BA. USFWS then provided a revised BO and commented that Section 7 of the Endangered Species Act of 1973, as amended, had been fulfilled. 15
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Environmental Assessment - Tennessee Valley Authority

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