The New York City Department of Environmental Protection (DEP) has retrieved a micro-tunnel boring machine from under the Schoharie Reservoir, marking another milestone for the $400 million infrastructure upgrade.
The micro-tunnel boring machine (MTBM) was lifted out on Wednesday from approximately 135 feet below the surface of the water.
In January the machine finished excavating 2,118 linear feet 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 9.5-foot-diameter tunneling machine began its work in 2017.
The tunnel was excavated in two segments, both starting at a 185-foot-deep shaft located alongside State Route 990V.
The first leg of the tunnel stretched 1,188 feet from the shaft to the eastern bank of Schoharie Creek. The second leg measured 930 feet 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 tunneling effort was one of the largest excavations ever by an MTBM that included a deep-water retrieval of the machine.
MTBMs are unmanned machines that are operated by remote control from the surface.
Operators tracked the progress and performance of the machine by watching it on monitors inside a control room.
Workers only entered the machine if it needed maintenance, or if cutters on the head of the machine needed to be replaced.
Significant work remains on the $142 million 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 $400 million 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.