Hydroelectric Generation

History

The founding of the City of River Falls is credited to Joel Foster in 1848, which soon brought more individuals to the area surrounding the Kinnickinnic River. There were names for the city such as Kinnickinnic and Greenwood, but in 1858 River Falls became the official name. Milling and lumber were important industries as Joel Foster himself opened up one of the first sawmills in the area.

Milling became the principal industry and many Yankee millers came to the area to capitalize on the river power. At one time there were five mills operating on the Kinnickinnic. Greenwood, Junction, Prairie, Cascade, and further downriver, the Dayton mill. The growing milling activity increased the need for shipping in additional wheat and shipping out flour. In 1878 the Hudson-River Falls Rail line was established. There were three successive years of drought and an infestation of cinch bugs that ended the viability of milling and shipping wheat from River Falls. The railroad continued until 1966 as more shipping went by truck.

Brian at Powell Falls.jpg

Junction Falls Dam was the first dam in the City, and began as a privately owned rock-filled timber dam to generate power for a mill located adjacent to the site. After a fire burned down the mill, it seemed the logical location for a municipal power plant. The City acquired ownership of the dam in 1900 with the help of local businessmen, creating River Falls Municipal Utilities. The hydroelectric power electrified lighting, replacing gas lamps throughout the city. The original hydroelectric facility at Powell Falls Dam, located approximately ½ mile downstream from Junction Falls Dam, was installed in 1903. In 1920, the City replaced the damaged timber crib dam at Junction Falls. New power houses were built at both dams in 1948 and around 1962 the steel tube penstock was encased in concrete at Junction Falls. The timber crib dam at Powell Falls was destroyed by high water and replaced in 1966. The City has since made repairs to the dams to improve the structure. The penstocks and powerhouses have remained the same.

Existing Facilities

River Falls hydroelectric facilities consists of dams and powerhouses at Junction Falls and Powell Falls.

The Kinnickinnic River flows south and west through the City of River Falls, Wisconsin. Both facilities operate in “instantaneous run of river mode” and will continue to operate as such. The hydroelectric facilities continue to supply energy to the City of River Falls electric grid, thus reducing the need for bulk energy purchases by the River Falls Municipal Utilities (“RFMU”), a division of the City of River Falls.

Junction Falls consists of a concrete gravity dam, 140 feet long, with an uncontrolled overflow spillway and a crest length of 115 feet. The headworks section of the dam is at right abutment and has two gated waterway openings; one 5 foot square for discharging excess flows; and one 6’ X 200’ encased pipe leading from the penstock to the powerhouse. The existing reservoir, Lake George, is 16 acres with a storage capacity of 142 acre-feet. The normal pool elevation is 865.3 feet mean sea level.

The powerhouse consists of a brick superstructure above a concrete substructure, (1) General Electric generator rated at 250 kW, 312 kVA, 2300 volts, 0.8pf 450 RPM 3 phase type ATI coupled to a Leffel hydraulic turbine 42’ design head 330bhp 246kW 450 RPM Type F year 1917. The transmission line is approximately 50 feet to the existing bus which connects to the 12.4kV system through a 2400-12.4 transformer. It is currently run in “run of river” mode, and the historic average flow rate of river is @95 cfs (USGS data retrieved October 29, 2013).

Powell Falls consists of a concrete gravity dam, 110 feet long and 22 feet high, with an uncontrolled overflow spillway. An integrated powerhouse/penstock is at the left abutment. The reservoir, Lake Louise, is 15.4 acres with a normal 37 acre feet capacity. Normal pool elevation is 821.80 feet mean sea level. There is also an intake gate integrated into the powerhouse and a 6’ waste-gate adjacent to the powerhouse.

The Powerhouse consists of a brick superstructure above a concrete substructure, (1) General Electric generator rated at 125 kW, 165 kVA, 2300 volts, 0.8pf, 3 phase Type ATI coupled to a Leffel hydraulic turbine 20’ design head 80bhp 134kW 240 RPM Type F year 1917. The transmission line is approximately 2,500 feet from the powerhouse to the control room at the Municipal Power Plant building, where it connects to the existing bus and to the 12.4kV system through a 2400-12.4 transformer. This unit is also run in “run of river” mode. The historic average flow rate of river is @95 cfs (USGS data retrieved October 29, 2013).

Operators use a prescribed outline when ramping the units up or down for intake cleaning and/or maintenance, with a 5kW increase or decrease no sooner than every 15 minutes. This is to ensure a smooth water discharge downstream. Ramping for intake grate cleaning is done only on an as need basis and scheduled so as not to be done on both units the same day. Heavy leaf load in the river during fall and excess debris in the spring are causes to shut the units off for a period of time and let the debris flow over the spillway.

With the discontinuation of the diesel generation at the River Falls Municipal Power Plant in 2011, the plant is no longer manned on a 24-hour basis. The operator makes daily visits to the Junction Falls Hydro Facility and weekly to the Powell Falls Hydro Facility. The outputs can be monitored from the Power Plant SCADA system.

Hydroelectric Relicensing Process (click for link)