BOST3 applies to change turbine number for 36-MW Louisiana hydro project

Editor’s Note: This content was originally featured on GenerationHub.com. GenerationHub.com is a sister site of HydroWorld.com that covers power generation in a number of renewable and non-renewable forms.

BOST3 Hydroelectric LLC on Nov. 11 applied at the Federal Energy Regulatory Commission for approval for a non-capacity related amendment to the Lock and Dam No. 3 Hydroelectric Project License, which covers a project on the Red River in Louisiana.

The commission had approved this license in April 2014. The plan presented in the original license application utilized a single 7.7 m diameter bulb turbine to provide 36.2 MW of generating capacity. The company has lately conducted preliminary design and cost estimates related to the installation of the single turbine unit. The results of the study indicate that an excavation depth of over 100 feet would be required to install the single 7.7 m unit.

An evaluation of the costs and construction techniques associated with a very deep excavation would require a specialized construction technique and associated bracing system. The foundation profile consists of clay and other deposits. The analyses indicate that in addition to being very costly, the deep excavation could require additional study and analysis to resolve any concerns regarding the adjacent U.S. Army Corps of Engineers (USACE) structures.

To reduce the risks and to allow the project to move forward in a timely manner, the company is now proposing an alternate design using five smaller turbine units which will significantly reduce the excavation depth. The proposed alternative will not change the 36.2 MW generating capacity of the project nor significantly change the maximum turbine discharge (19,085 to 19,055 cfs). The proposed alternative will also significantly reduce the risks and issues associated with construction adjacent to the existing spillway structure.

As indicated in the current license, the project will interconnect with an existing 230-kV transmission line located approximately 1,800 feet south of the proposed powerhouse. This transmission facility is owned by Central Louisiana Electric Co. (Cleco). Recent discussions with Cleco indicate that the most efficient location to interconnect to this line is approximately 2,500 feet west of the location shown in the current license, BOST3 added. Accordingly, the project boundary has been revised to reflect the preferred interconnection location. 

This hydroelectric project will be located at Lock and Dam No. 3 on the J. Bennett Johnson Waterway. Lock and Dam No. 3 is located near the City of Colfax, 38 miles upstream of Alexandria, Louisiana, at approximately river mile 116.5. Lock and Dam No. 3 is one of five navigation lock and dam structures that comprise the J. Bennett Johnson Waterway on the Red River. Lock and Dam No. 3 was designed and constructed under the direction of the U.S. Army Corps of Engineers, Vicksburg District. The navigation project was completed in December 1994. The Corps of Engineers, Vicksburg District, operates the J. Bennett Johnson Waterway.

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Elizabeth Ingram is content director for the Hydro Review website and HYDROVISION International. She has more than 17 years of experience with the hydroelectric power industry. Follow her on Twitter @ElizabethIngra4 .

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