After grinding its way through stiff Potomac Clays under Washington, D.C., for exactly one year and a day, a tunnel-boring machine (TBM) named Nannie finally reached its destination, bringing closer to completion a massive project to improve the quality of life of the city’s residents.
The U.S. capital is spending billions of dollars on the construction of a network of tunnels and other structures in a bid to reduce the amount of untreated storm water and sewage flowing into its prized waterways.
This effort, known as the Clean Rivers Project, has enlisted the help of experts in the field, including Salini Impregilo and SA Healy, whose workers guided Nannie towards its destination by breaking through the wall of a shaft and then into an adjacent tunnel some 100 feet below ground late one November evening.
With its large cutter-head finally coming to a rest, workers broke into applause.
Flashes lit up the completed tunnel as they posed for photos, their wide smiles revealing the pride they felt for what they had accomplished: the excavation of a 2.5-mile tunnel under a train track, river, highway and subway line.
The breakthrough marked the completion of the excavation phase of the Anacostia River Tunnel (ART), part of the project being done by the joint-venture made up of Salini Impregilo, SA Healy and Parsons.
«Our Clean Rivers Project team continues to push forward at an incredible pace, and the completion of this tunnel is another key milestone to celebrate,» said DC Water Chief Executive and General Manager George S. Hawkins. «We applaud everyone who has played a part in keeping this work on schedule to meet our ultimate goal, which is cleaner water everyone can enjoy. That will be a great return on the investment our ratepayers are making in this massive project.»
The ART is one of five tunnels planned under the ambitious the project by the District of Columbia Water and Sewer Authority (DC Water) to protect Rock Creek and the Anacostia and Potomac Rivers.
Like other cities, Washington, D.C., has a combined sewer system that is often overwhelmed by large flows of water that come with storms and heavy rains. In order to avoid flooding streets and homes, regulators allow excess flow to discharge a dilute mixture of untreated storm water and sewage – known as combined sewage overflow (CSO) – into the nearby creek and two rivers.
As a result, there may be risks to public health because of these rapid flows and the potentially harmful substances they may contain– something DC Water wants to avoid.
WORKERS HAVE FINISHED BORING A TUNNEL FOR A PROJECT TO HELP WASHINGTON, D.C., MANAGE SEWAGE AND STORM WATERS
THE ANACOSTIA RIVER TUNNEL (ART) WILL BE PART OF AN UNDERGROUND NETWORK TO STORE WATER AND SEWAGE OVERFLOWS
THE CITY’S CLEAN RIVERS PROJECT AIMS TO REDUCE TOXIC OVERFLOWS IN NEIGHBOURING WATERWAYS
THE HEALTH OF THE CITY IS LINKED TO THE HEALTH OF ITS RIVERS