MTBM removed from Schoharie Reservoir15 July 2019
New York – The New York City Department of Environmental Protection (DEP) announced July 12 it retrieved a the MTBM from the waters of the Schoharie Reservoir, marking another milestone for the USD 400M program to upgrade infrastructure and improve operational flexibility at the northernmost reservoir in the City’s water supply system.
The MTBM lifted took place on July 10 where it had finished excavating at approximately 135ft (41m) below the surface of the water. In January the machine finished excavating 2,118 linear feet (645m) of tunnels that will be used to release water downstream of the reservoir into Schoharie Creek.
“The completed excavation and retrieval of this tunneling machine are major milestones in our work at Schoharie Reservoir,” DEP commissioner Vincent Sapienza said. “The new release works and upgrades to our intake structure at the reservoir will provide DEP with more operational flexibility to send the best-quality drinking water to New York City and support the ecological health of Schoharie Creek.”
The 9.5ft- (2.8m-) diameter MTBM began its work in 2017. The tunnel was excavated in two segments, both starting at a 185ft-deep shaft located alongside State Route 990V. The first leg of the tunnel stretched 1,188ft from the shaft to the eastern bank of Schoharie Creek. The second leg measured 930ft from the shaft to the bottom of Schoharie Reservoir, where the MTBM excavated through the reservoir bottom on January 19. After the winter ice melted, engineers set up a system of barges and lifts to remove the MTBM from the water on Wednesday.
"The entire tunnelling effort was unique – it was one of the largest excavations ever by an MTBM that included a deep-water retrieval of the machine," a spokesperson said for the DEP.
Significant work remains on the USD 142M project to build a release works at Schoharie Reservoir. Now that the release tunnel is excavated, workers will focus on lining the tunnel and installing its intake structure. Work is also continuing on the eastern shore of the Schoharie Creek, where crews are building a valve chamber that will control the flow of water from the reservoir into the creek. The new release works will give DEP the ability to release water downstream of the reservoir into Schoharie Creek to facilitate dam maintenance, respond to potential emergencies, mitigate flood risk for downstream communities, and enhance downstream habitat for fish and wildlife.
The release works are part of a USD 400M program to upgrade all the water supply infrastructure at Schoharie Reservoir. The program began with the full-scale rehabilitation of Gilboa Dam, which was completed in 2014. It also includes significant repairs and upgrades at the Shandaken Tunnel Intake Chamber, which conveys drinking water from the reservoir into an 18-mile tunnel on its way to Ashokan Reservoir in Ulster County. Learn more about the Schoharie Reservoir infrastructure program.