Spotted today on the towpath at the Oxbow area in Fairport, several surveyors in two vans, looking at a potentially dangerous area where there is a leak right under an badly positioned R.G& E electricity pylon atop the dam.
The situation here is grave, because the embankment slope is very steep. Right under the pylon, the dam is leaking so badly there is a large patch of Cat-Tails and Red Twig Dogwood. These plants only grow in damp and wet areas, so are a good indicator of a long established leak.
A slippage of saturated soil here could pull the pylon down, losing power to hundreds of people and breaching the embankment.
Earthen Embankment Dams are designed so water naturally soaks through the dam and drains through to the ground level. This happens on an angle, and if the design is correct, the water exits below the ‘toe’ or bottom of the slope.
If the situation is wrong, as in our case, the water will exit above the ground level.
Then the dry upper soil slides on the slippery mud underneath, and the dam collapses.
So, here’s what the NYPA is going to do!
Starting next week! Contractors are going to drive steel sheeting panels 2′ wide and 30′ deep directly into the crest of the dam to block off the Phreatic Line and make it flow as in the diagram above. This work is scheduled to cover 200 feet of the worst areas along the Oxbow.