1907 Croton and 1931 Hardy Dams on Muskegon River

(Croton Satellite, Croton HAER, Hardy Satellite, Hardy HAER)

There is also a Croton Dam in New York.

Croton Dam

Electricity from this dam was transmitted at 100 kVA. [reference.insulators.info] The output of the Lockport Powerhouse was transmitted at 66 kVA.

Photo by Ted Gregory

Digitally Zoomed

I added the label wwDamTech because the center spillway is a rare example of a bear trap gate. The photo caption taught me that this is also called a shutter gate. This photo was taken after 1991 because that is when the travelling gate hoists (crabs) were replaced with stationary hoists. [mi0529]

Photo from mi0529 from near the bottom of mi0413
VIEW NORTHEAST, DETAIL OF SHUTTER (BEARTRAP) GATE PIERS, WITH TUMBLE BAY AND WEIR IN FOREGROUND

I'm glad they confirmed that 110,000 volts was the highest in 1907. That struck me as high for that time period. Once again, we see a hydroelectric power pushing transmission voltages because companies could build coal-fired plants near their customers, but they had to build hydro dams where a river was.

Mary Hofman, more plaque photos on TravelTheMitten

The structure downstream of the Tainter gates looks rather unique. Thanks to DanielG's comment, I've learned that what I called splash pools are properly called Tumble Bays. Scrolling through the photos on Google Maps, there are quite a few that catch the spillway in action. But none of them use the beartrap gate. Phil Richiuso even caught a view from the side where we can easily see how a pool of water helps dissipate the energy of the falling water. Of the photos showing the spillway in action, below has the max flow of three gates half open. In the Spring of 2013 there were heavy rains and there was a possibility of downstream flooding.

mlive via Google Maps

mi0529data, p6
The tumble bay weir is 20' high and 12.5' thick at the base. p3

As part of building the embankment, we can see the building of the forms for the corewall. They would have already driven a sheet steel cutoff wall under the corewall location up to 36' into the river bed. The cutoff wall stops water from percolating under the embankment, and the corewall stops water from percolating through the embankment. [mi0527]

Engineering Record, p419
[I wonder how they are diverting water under the tumble bay weir.]

When I first read that the generator building was west of the turbine building, I was confused about why there were two buildings until I remembered how old this plant was. The early hydropower plants like this one in Lockport used a horizontal shaft because a thrust bearing that could handle the weight of a vertical shaft had yet to be developed.

US Goverment, HEAR IL-197-C from il0979

Engineering Record, p422

Engineering Record, p422

Both the Lockport and Croton powerhouses have had their horizontal shaft equipment replaced by a couple of vertical shaft turbine and generator sets. Lockport replaced several units with just two so they kept some of the old generators as museum pieces.

The caption below why they used a beartrap gate and regular spillway in the middle --- log sluice. The feature of a beartrap gate is that it goes down and water goes over it. This flow of water over the gate also allows debris such as ice and trees to go over the dam. In Michigan, logs going down rivers were not debris, it was deliberate and a pillar of their economy. It was standard practice to cut trees during the winter and drag the logs to the bank of a river. Then when Spring thaw and rains started, the logs would be formed into rafts and taken downstream to a sawmill. Sometimes the log rafts would jam up and take out bridges.

Engineering Record, p420

It looks like 3 gates were half open in Feb 2018 also.

Casey Chatman, cropped

If you scroll through the Croton Google Map photos, you will also see that they catch some pretty big fish here

The earth embankments were built using hydraulic sluicing. In short, William Fargo used pumped river water to wash a nearby hill down into the river. This idea was clever enough that someone else tried to claim credit for it. [mi0527]

Engineering Record, p422

Engineering Record, p422

Hardy Dam

This 100' high earth dam was more than twice as high as any other dam built by Consumer Power. So the basic design they had used of incorporating the intake values in the power house was changed. This dam uses an intake tower on the upstream toe of the embankment and a powerhouse in the downstream toe. They are connected by three 14' penstocks through the embankment. At the powerhouse, the 14' penstock feeds a 12' penstock which supplies the Francis turbine scroll cage. The rest of the water goes through a pipe controlled by a butterfly valve to an internal spillway. The storage capacity of the reservoir and this internal spillway can handle most floods. But as a conservative design, a standard spillway was constructed on the other side of the dam. [mi0439] Evidently that spillway was needed in at least 1986. [mlive] I wonder how low the reservoir was before the 14" of rain fell. The flood down by Maple Island Road would have been worse if Hardy had not retained some acre-feet of water.

When Croton was built, hydro power was used for base power and coal plants were used for peaking power. By the time this dam was built, the economics of coal plants had improved so much that they were used for base power and hydro was used for peaking power. One high dam was built instead of a couple of run-of-river dams to have a large storage pond to improve its utility as an emergency backup for the coal powered plants in the system. [mi0439]

Larry Pieniazek, CC  BY-SA

This display at Hardy Dam is a Francis Turbine. Maybe I'll pay more attention to antique tractor shows in Michigan so that I can take a side trip here and get photos from more angles.

Photo from TravelTheMitten

It was turbine #3, which was replaced in 2009.

Photos courtesy of Consumers Energy, by Harry Sabourin from MichiganBuildingTrades
[Note the total capacity of Consumers Energy's 13 hydro plants is 132Mw. A single unit in a modern coal-fired plant can produce over 600Mw. It is a real shame that the USA spent money on putting men in space instead of pursuing new design ideas for safe nuclear power.]

Photo from mi0439 from near the bottom of mi0413

Feb 1, 2018: Portion of Hardy Dam wall to emergency spillway damaged, no danger to public

Emergency spillway photo

A copy of the links provided by DanielG in the comments to make them "clickable":

• https://www.loc.gov/item/mi0413/ 
• https://www.loc.gov/resource/hhh.mi0528.photos?st=gallery
• https://www.google.com/search?q=don+harrisons++hardy+dam+builders+photos&tbm=isch&tbo=u&source=univ&sa=X&ved=2ahUKEwizj8ij3I7eAhXEc98KHcaBBQsQ7Al6BAgGEBs&biw=1280&bih=676
• https://books.google.com/books?id=501RAQAAMAAJ&pg=PA89&lpg=PA89&dq=croton+dam+michigan+high+voltage+insulators&source=bl&ots=0uRZPCO6bp&sig=kOuF7vp4HJG3qQc54P01swk81uQ&hl=en&sa=X&ved=2ahUKEwiWy4ft8__eAhVqooMKHT5CCb8Q6AEwBnoECBQQAQ#v=onepage&q=croton%20dam%20michigan%20high%20voltage%20insulators&f=false
• https://reference.insulators.info/publications/view/?id=5572