Tunnel shutdown to end by April 30
Reviews are expected to be completed by April 30 on the reservoir gates that control the flow of water.
New York City Department of Environmental Protection officials expect engineering reviews will be completed by April 30 on Schoharie Reservoir gates that control the flow of water through the Shandaken Tunnel.
The tunnel, which has been shut down since March 1, normally carries water 18 miles from the reservoir to
an outlet in Allaben, where it flows into the Upper Esopus Creek.
City spokesman Adam Bosch said the review is needed as part of a $47 million project to repair an intake chamber at the Schoharie Reservoir.
“It has some structural issues related to some gates that don’t work and the gates that do work are really old and just really need to be replaced,” he said. “The chamber itself needs to be refurbished because that chamber is not only a gate chamber to work the intake, but it’s also the reporting location for a dozen of our employees. So it needs to (have) lead paint taken out, windows replaced,
just some of the physical plant stuff.”
City officials are required to get state Department of Environmental Conservation approval for changes in discharges from the tunnel. The upgrades are expected to provide flexibility in how Upper Esopus Creek conditions are addressed by water discharges from the reservoir via the tunnel.
Bosch said the scheduling of the work was done after consulting with fishing enthusiasts.
“We looked to find a time of the year when the natural flow in the creek was particularly high and when the temperatures were naturally quite low,” he said. “As it happens the best time of the year for that is this March-to-April time frame because that’s when the snow is generally melting from the mountains
and the flow is high because we’re getting spring rains.”
Bosch said equipment will be added to the tunnel intake chamber that allows water to be taken from different depths at the reservoir.
“At least 100 million gallons of what we send through the Shandaken Tunnel can come from multiple different levels where previously this structure only had an intake at more or less the very bottom of the reservoir,” he said. “This will help not only with the quality of water that we can send through the tunnel, but also preserving the cold water longer throughout the year, which is important to the trout fishery in the Upper Esopus.”
The flow of water through the tunnel ordinarily runs between 120 to 200 million gallons per day depending on
water conditions.
Over the next six weeks, divers will go to depths of 130 feet to take sonar measurements that will be used to replace eight gates that were installed during the 1920s. In a press release, officials wrote that three of the gates are currently stuck after breaking from their lifting mechanisms and becoming wedged in place, with replacement work to be done during two-month shutdowns in each of the next two years.
“The tunnel will be shut down ... while workers install a plug and bypass system within the intake structure,” they wrote. “The plug will block the flow of water into the Shandaken Tunnel and prevent divers from being pulled into the tunnel while they remove and replace the old gates.”