1989-1991 Dam Repair Project
The following pictures depict some of the dam repair project that occurred from 1989 to 1991. Unfortunately the pictures are not clear because a rudimentary procedure was used to digitize them. A VHS tape was turned into a DVD. Then while playing the DVD on a computer, a "screen capture" was used and saved as a "pict" file for editing and to save space. Then the final was converted to a "JPEG" format for use on the web site. Some information is added from memory and I apologize for grammatical errors, I flunked 12th grade English. Thank goodness for spell check.
In the late 1980’s, the NYS division of canals and waterways controlled the reservoir water level. Many issues had built up over time regarding the safety and integrity of the dam.
1- Many leaks developed through the overflow spillway that allowed large amounts of water out and more importantly, possibly breaching of the spillway. This would have caused a permanent 3-foot drop in the reservoir. The spillway on the backside of the dam was filled with junk and in disrepair.
2- The underground drainage tiles were not functioning causing some "wet" areas and some manholes needed to be replaced or reset. Wet areas surfacing indicated that the normal leakage through an earthen dam was not being collected and funneled away from the soil which could eventually erode and cause a breach in the dam. With some of these areas being 20 to 30 feet below the crest elevation, the reservoir would have permanently been lowered by that amount. You think the 3-foot winter drop is a lot?
3- The outlet gates were in bad shape. The middle gate could not be closed completely causing a large loss of water during the summer. The other 2 were difficult to move. These 3 twelve inch gates were installed around 1932 and attached to the original 20 inch valve bodies that were installed around 1862 during construction of the reservoir. At that time, 1932, it is thought that the stems, gates and bonnets were removed from the original 20 inch valves and blank flanges were added in their place.
During the planning of this project, state engineers in Albany wanted to lower the lake by 20-30 feet to prevent a major breach when the drainage system was repaired. Fortunately, the local canal engineer, Mr. John Baldwin, convinced his higher ups that it could be repaired safely without a big drop. If needed, sheet piling could be used. Also it wasn’t clear if the inlet pipes in the lake, approximately 50 feet below the surface, could be capped so the old valves could be replaced.
The following pictures capture the essence of the project. I apologize for the lack of clarity.
Spillway Before Cleaning 5-9-90
SPILLWAY AFTER CLEANING - APRIL 23, 1991
BACKSIDE BEFORE CLEANING - MAY 9, 1990
BACKSIDE OF DAM AFTER CLEANING - APRIL 23, 1991
OVERFLOW LEAKAGE PRE REPAIR - MAY 9, 1990
OVERFLOW SEALED POST PRESSURE GROUT - APRIL 23, 1991
UNDERWATER DIVER WORK
Timbers in cross brace. Divers glove lower right
Sometime around 1932, 3 gate valves were installed on the 1862 original 20-inch valves. At that time, it is believed that the lake was either lowered or pipes were blocked off for this repair. The 20 inch valve stems and gates were removed and covered with a blank flange leaving the bodies to bolt the new valves onto. Over time, the 1932 valves began to malfunction. The center one could not be closed and the other 2 worked very hard. Replacement was the only option.
As mentioned earlier, once the flow was shut off with the pie plates and it was determined safe, the original 1862 valve assemblies were removed. Three special adapter flanges had to be fabricated to match up to the bolt patterns of the new 12-inch valves with the 1862 pipes that go into the lake.
The slippery old wood floor was removed and 6 new 12-inch gate valves were installed. Each pipe got 2 new valves. The 3 valves closest to the lake would remain wide open and the 3 furthest from the lake would be used to control the flow. Using this procedure, in case the control valves ever needed replacement, the upstream valves could be closed. This would eliminate the need for a diver to install pie plates or worse to empty the lake. The following pictures document the work.
Old valves and wood planking floor that was extremely slippery due to water spray and scum build up. The middle valves were unusable.
Valve house with cover removed showing old deteriorated unsafe steel metal access ladder. Note broken rung 4th up from bottom.