Gate Automation for License Compliance of Minimum Flow Releases and High Flow Events

摘要

On March 1, 2005 Alcoa Power Generating Inc.'s (APGI) new license became effective for the Tapoco Hydroelectric Project. A Relicensing Settlement Agreement (RSA), negotiated over a period of several years between APGI and its' stakeholders, provides additional flow releases, protecting fish and aquatic habitat, while enhancing recreation opportunities. As part of the RSA, APGI must provide a continuous minimum aquatic base flow between 40 and 100 cfs from Santeetlah Dam to protect aquatic resources, the biological integrity and water quality in the Cheoah River bypass reach. The RSA also has provisions for providing 19 to 20 high flow event release-days per year, with peak maximum flows of 1,000 cfs APGI determined early in the negotiating process that the six, 25-ft wide by 12-ft high Tainter gates at Santeetlah Dam were not a cost-effective means for providing the aquatic base flow release. In order to meet the negotiated aquatic base flow releases, four 5-ft 7-in wide by 1-ft 7-in high mini-gates were installed in two Tainter gates The mini-gates are also used for ramping flows associated with the high flow events. The Tainter gates are used to provide the high flow event releases. However, to account for the normal fluctuation of the reservoir headwater elevation and to minimize the need for manual gate operations, automation of all gate operations, including the two mini-gates and the six Tainter gates, was required. This paper focuses on the operational challenges that were encountered during the implementation phase of the gate automation process. Some of the challenges were programming the control logic, public safety issues, mechanical, electrical and controls upgrades to the gates, winter month operations, ramping of high flow events, and minimization of excessive gate operation. This paper discusses the overall approach, as well as lessons learned throughout the engineering and design phase, construction and installation process and implementation phase.