PPL Montana’s board of directors has authorized $175 million to construct a new 60-MW Rainbow hydroelectric plant on the Missouri River that will replace a 35-MW Rainbow plant that is part of the 326.9-MW Missouri-Madison project.
Plans for the new Rainbow powerhouse are included in PPL Montana’s operating license for Missouri-Madison (No. 2188), an eight-powerhouse project. The Federal Energy Regulatory Commission issued that license in 2000, effective through August 2040.
PPL Montana, which approved the funding in February, said it plans to begin building the new powerhouse in spring 2009. It is to feature a single 60-MW turbine of an improved, ï¿½fish friendlyï¿½ design. While the company is several weeks away from signing a contract for a water-to-wire package, it said the new unit would replace eight units at the existing powerhouse.
ï¿½The redevelopment of our Rainbow hydroelectric plant will add renewable energy in an environmentally friendly way and help meet the region’s need for new sources of clean, reliable electricity generation,ï¿½ PPL Montana Vice President and Chief Operating Officer Brad Spencer said.
Construction is subject to federal, state, and local approvals. The new facility, to be built on a hillside about 200 feet downstream of the existing powerhouse, is expected to be in service by spring 2011. The original powerhouse will be closed after the new one begins service.
In 1991, PPL Montana’s predecessor, Montana Power Co., contracted with Black &Veatch to study the feasibility of redeveloping Rainbow. The study identified several alternatives in optimizing the operation of the facility. Washington Group International Inc. prepared a report in 2007 evaluating the findings of a site investigation program and previous investigations at the project.