Design and Construction of the Moose River Hydroelectric Project

The project's main features are: a 7 ft high, 240 ft long cast-in-place concrete overflow weir; bell mouth entrance concrete intake structure with trashrack and trashrake; 15 ft wide by 18 ft high slide gate and an adjacent rock excavated open channel ice sluice; 15.25 ft diameter unlined power tunnel which is approximately 4,500 ft long and which was excavated by a tunnel boring machine (TBM); a 30 ft diameter by 74 ft high below ground concrete lined air pressurized surge chamber located at the downstream end of the unlined power tunnel and approximately 450 ft upstream of the powerhouse; This paper discusses the design and construction of the project's main features including the unique application of the air tight high density polyethylene (HDPE) lining in the air pressurized surge chamber. The procedures developed for filling and operating the tunnel and pressurizing the air chamber are also discussed.