New York City Announces Completed Rehabilitation of Gilboa Dam
$138 million public safety and water supply project completed two years ahead of schedule
(NEW YORK, NY – November 3, 2014) – New York City Department of Environmental Protection (DEP) Commissioner Emily Lloyd today joined local, state and federal officials, dozens of construction personnel, and upstate residents to celebrate the completed full-scale rehabilitation of Gilboa Dam.
The $138 million dam reconstruction – believed to be the largest public works project in the Catskills – was completed two years ahead of schedule. The project included the addition of approximately 234 million pounds of concrete, molded and dyed to resemble the original bluestone face of the dam, more than 500 massive spillway slabs, and upgrades to the abutment walls that support the dam. Dignitaries who attended Friday’s ceremony poured Schoharie Reservoir water onto the finished dam for the first time to celebrate its recommissioning.
Gilboa Dam is 2,024 feet long, 155 feet high, and more than 150 feet wide at its base. Several new features were added to the dam during its rehabilitation, including an inspection gallery inside the dam that runs its entire length. The gallery – which also includes instruments to constantly measure stress on the dam – will allow engineers to visually inspect the inside and outside of the dam on a regular basis. The dam was also designed with 3-, 6- and 12-foot steps that dissipate the energy of water as it spills from the reservoir. The east and west abutment walls that support Gilboa Dam were also strengthened through the installation of 40 post-tensioned anchors, or steel cables that pull them tight to the bedrock. The project employed as many as 180 tradesmen from in and around the watershed through an agreement with local unions.
The rehabilitation was completed ahead of schedule despite a nine-month setback in the wake of Hurricane Irene, which inflicted historic damage upon the Catskills and the City’s water supply. The powerful storm sent roughly 8 feet of water over the dam’s spillway, destroyed much of the staging area for construction, along with access roads and work platforms. The project also adapted to limitations on some construction work after a pair of bald eagles built two nests near the dam’s west support wall. DEP was required to curtail some construction work during the eagles’ breeding season, along with monitoring the eagles and their hatchlings, which are protected by federal law.
While work on Gilboa Dam is complete, construction at the site will continue until approximately 2020. The rehabilitation of Gilboa Dam is part of a $400 million program to build and improve other facilities near the dam. This includes a permanent release tunnel that will replace the temporary siphons, giving DEP the ability to release water from Schoharie Reservoir around the Dam and into Schoharie Creek below. The remaining projects also include site restoration, rehabilitation work on the Shandaken Tunnel Intake Chamber, and the construction of a public information kiosk off Route 990V.
For more information, please visit the NYCDEP website.