From the dedication ceremony program:
The Medahl project was developed jointly by American Municipal Power and member community Hamilton, Ohio. The city of Hamilton retains rights for a 51.4 percent share of the energy output while AMP retains rights to the remaining output for 47 other AMP members participating in the project.
Excavation and cofferdam construction began in May 2010, and powerhouse construction began in August 2011.
428 construction jobs (peak) were created over the construction period.
2.45 million labor hours were worked by contractors.
1,141,877 cubic yards of earth were excavated, equivalent to about 100,000 dump truck loads.
114,389 cubic yards of concrete and 12,838,044 pounds of steel were used to build the plant.
More than nine stories of the 10-story powerhouse are under water.
The powerhouse is designed to be overtopped during flood events by as much as 25 feet of water.
The powerhouse crane spans 190 feet across and can pick up a maximum load of 175 tons, which is about the weight of a Boeing 747 jumbo jet.
At peak flow, nearly 8.6 million gallons of water, enough to fill 13 Olympic-size swimming pools, will pass through each unit per minute.
The facility is fully staffed by Hamilton employees, with nine operators and two management personnel on staff.
Full commercial operation began in April 2016.
From Phil Meier of AMP during a tour of the plant:
The turbine rotates slowly, at only about 60 rpm, which gives them a “very long wear life.”
The plant has 30 miles of cable. It also has about 1,000 monitoring points on 39 different systems.
The turbine blades are variable pitch. They can rotate about 21 degrees maximum.
Turbines are 7.7 meters in diameter.
The plant can operate in two modes: The norm is for maximum megawatt production. The other is for river flow control.
The Meldahl project is built on rock, as the soil there is not deep. Plants AMP has built at the Smithland and Cannelton locks and dams, however, are built where the soil is 100 feet deep or more, so builders had to erect them on stone columns.