Spillway Repair Project February 2022

Below are pictures documenting the Repair Project.

The overflow spillway developed numerous leaks during the two-year dam repair project completed in 2021. The lead contractor on this job was Tioga Construction from Schuyler, NY.

The theory is that when they installed the “coffer dam”, large sandbags on the spillway to prevent flooding when they poured the new spillway, the weight of the sandbags fractured the grouting that was installed back in the 1998-2000 repair project. This fracturing allowed fissures to develop that allowed a large volume of water to seep through. So, as part of the overall dam repair project the state has designed a project to repair the spillway leakage. 

Looking West from Dam Road showing some of the equipment for the repair project staged in the parking area. The red piece of equipment is a heater that will circulate a glycol solution through many hoses run under the road and spread out on the spillway "hopper" (my term).

From Dam Road - shown is the tarp over the southern side of the spillway.  The first day the contractor showed up, Tuesday, February 21, 2022 they had to shovel a large amount of snow out of the spillway so the tarp could be installed over the entire spillway. This was to allow heating the entire spillway to thaw out the ice in the fissures and allow for injecting pressure grout to fill voids in the spillway and reduce leakage.

Tarp applied over the spillway on the Dam side to contain the heat being applied by circulating heated glycol through hoses run under Dam Rd. 

The equipment above on the road is a trailer that has the grouting mixer and pressure pump to fill the voids in the spillway.

Looking East from the spillway. All the black hoses are circulating heated glycol to thaw and warm the work area inside the spillway enclosure. The contractor pressure washed the complete spillway including the fissures to ensure that the grout would have a clean surface to adhere to. As you can see, the area is quite clean as this was filled with decayed weeds and other "stuff" that floated up before the fall drawdown.

The white pvc pipes were installed in the openings for use to feed the pressure grout into the spillway using the blue valves to control the flow/volume of the grout. Once completed, these pvc pipes will be cut off and sealed. 

Prior to grouting, the contractor had to "point" (Pointing is the finishing of mortar joints in brick or stone masonry construction") all the large openings and seams in the stone. There were places that you could see right through to the water side. Further, this pointing sealed the area seen so the pressure grout would find the fissures within the spillway stone rather than blow back into the spillway.

Same as above but looking towards the west inside the spillway. Note all these pipes will be cut off and sealed.

Close up of a grout pipe installed and the "pointing" of the seams. 

It's hard to notice, but note the water running through at the base/floor of the spillway. The Reservoir level had come up about a foot from the recent warm weather and snow melt. This will be explained later how the repair was done.

Looking west, close up of contractor pressure grouting a seam. Pressure applied was between nine and ten PSI to force grout into the fissures towards the water side. The contractor is in radio contact with the grout mixing and pumping crew located on Dam Rd above. 

This is the trailer carrying the grout mixing and pump that pumps the grout into the pvc lines installed into the face of the spillway. Eleven bags of grout were used. The contractor is GroutTech, Inc. from Glens Falls, NY

Looking North from the spillway. Some of the equipment used and stored under Dam Road. 

Notice the volume of water that is leaking through the base/floor of the spillway due to level up a foot from recent snow melt.

Close up of the base/floor leak. The Reservoir level came up about a foot from a few days of warmth and snow melt. There were several areas along the lower part of the spillway that were leaking. The pressure grout could not be used due to the running water and it would be washed out before curing. So a special foaming process was used for this issue.

Looking South East at the base of the spillway. Due to water flowing in around the base of the spillway, the pressure grout could not be used because it would be washed out before curing.

So the State had the contractor use a special industrial foaming agent that expands at ten times its volume. It is something like the stuff you buy at a hardware store in a can called Great Stuff that fills voids in dry areas of a home. This stuff is different as it works in water. The state has had good luck and is used in a lot of their locks.

Look close at the picture, ignore the yellow wire, those are electric leads from a generator outside the enclosure. But looking close you can see a small (1/4 inch?) copper line running from the pressure gage assembly and goes into the stone where the foaming agent is pumped. 

Prior to pumping the foam, the joints are filled with that brown stuff that looks like a rope. That is Oakum which is used in plumbing, ship building, masonary projects, etc. It is like a hemp that swells when wet. (this is not the "consumable" type hemp so please don't remove it for personal use). This Oakum helps contain the foaming agent being pumped into the stone to allow it to expand into any fissures. The pizza box is not used for any repairs as far as I know.

I will try to get some pictures hopefully before the level crests to see if the repairs worked and will notify state if any issues develop. Hopefully the level crests but we need either more snow or spring rain. Currently as of February 25, 2022 we are about two feet below crest.

Repairs completed. Looking west from inside the spillway. All grout pipes removed and sealed. Level approximately .6 feet below crest. No leakage. The wet area on the "floor" is from melting snow.

Another excellent job by the Canal Corp. completing this repair during winter and level coming up. This allowed the Reservoir to reach crest, assuming we get enough precipitation, rather than keeping it down to complete the repairs during the warmer months.