John Day Dam Drilled Waterstop

The John Day Lock & Dam is a straight-axis concrete gravity dam with a powerhouse consisting of 20 monoliths. Commissioned in 1971, the original waterstops have failed and leakage was entering the powerhouse galleries and operating floors along the monolith joints. A project to repair 3 leaking joints was performed two years prior as a precursor to this project. The effectiveness of the repair on the original 3 locations resulted in the scope to repair the remaining joints under this project.

SCOPE OF WORK
At each of 18 leaking monolith joints, a remedial waterstop was to be installed to mitigate the leakage into the powerhouse. At each location, a 6” diameter borehole was drilled along the joint from the top deck to a depth of 5’ into the foundation. Each borehole was inspected for any voids or honeycombing in the concrete sidewalls of the borehole. A neat-cement grout was used to repair any defects within the borehole that could create a potential leakage path around the seal.

After a final video inspection of the borehole, Emagineered Solutions’ CYLutions™ remedial waterstop cyinders were installed in a column within the borehole up to 3’ from the intake deck. A mechanical packer was placed on top of the cylinder stack to resist uplift of the cylinders as they expand in the presence of water.

RESULTS
In the weeks following installation of Emagineered’s CYLutions™ remedial waterstop cylinders, the leakage at all joint locations was dramatically reduced or eliminated. Dye testing that was originally scoped for checking the source of leakage after installation of the waterstops was cancelled, as no leaks remained. The new watestop seals remain effective today.