Each January, tunneling and underground professionals gather in New York City for the George A. Fox Conference. The one-day event offers attendees the opportunity to listen to their peers outline what’s new in the underground construction industry, get updates on major projects in North America and have a chance to catch up of old friends.
The conference is put on by the Underground Construction Association of SME. This latest conference attracted about 370 specialists in the industry. The theme for this year’s event was “Water Tunnels, Past, Present and Future.”
The technical session included talks focused on major tunneling projects, including the massive California Water Fix program and the Massachusetts Water Resources Authority (MWRA) Metropolitan tunnel redundance program in Boston. The conference also included an update on the Gateway Project from Phil Rice from WSP and Mahammed Nasim of Amtrak as well as a Tunnel Industry update.
The following is a sample of a few of the presentations.
DEP’s Tunneling Program Evolution. James Mueller is the agency chief engineer of New York City’s Department of Environmental Protection (DEP). Its mission is to plan sustainable infrastructure investments for the future of clean water and the environment in the city and its watersheds, he said. The agency’s goals are to synthesize information across bureaus within DEP to allow data-driven decision-making. It is also to optimize internal agency processes and systems related to the implmenation of engineering programs within a structured assessment process. The agency also prioritizes projects and funding within a structured integrated planning process. And it standardizes project performance and delivery to meet the needs of the agency in alignment with industry standards and market capabilities.
The DEP’s Bureau of Water Supply manages New York City’s 485,640-ha (1.2-million-acre) watershed, of which more than 51,400 ha (127,000 acres) are owned by DEP, Mueller said. The bureau supplies more than 3.7 GL (1 billion gal) of quality drinking water daily to more than nine million residents of the state. And the Bureau of Water Supply manages the 19 reservoirs and three controlled lakes with a storage capacity of 2.19 TL (579 billion gal), he said.
The agency’s Bureau of Water and Sewer Operations distributes drinking water throughout the city and collects sewage and storm water through 21,000 km (13,000 miles) of sewer and water mains. The bureau also oversees enforcement of regulations governing water-service lines, sewer connections and cross connections, in addition repairing and maintaining DEP infrastructure.
Meanwhile, the city’s Bureau of Wastewater Treatment treats 4.5 GL (1.2 billion gal) of wastewater daily, Mueller said. The bureau maintain 14 wastewater treatment plants, 96 pumping stations, four CSO storage facilities and 210 km (130 miles) of interceptor sewers.
Mueller went on to explain the DEP’s drinking water tunnel program, using the Kensico-Eastview Connection Tunnel as an example. The goals of the project are to enhance operational resiliency and redundancy, provide target capacity to meet future water demand and enable Catskill aqueduct bypass of the Kensico Reservoir. Other goals of the project are to facilitate emergency and planned outages, provide compatibility with future projects and enable the future bypass of the CDUV facility.
There are several significant factors in the decisionmaking process for drinking water tunnels and CSO storage tunnels in New York City, Mueller concluded. Durability is one of them. Once in place, tunnels are generally secure assets with long expected lifespans for more than 100 years, he said. So there is a need to plan for future conditions over the 100+ year timeframe.
MWRA Metropolitan Boston Tunnel Redundancy Program project update. Kathleen Murtagh is director of the MWRA. Fred Brandon is director of MWRA’ Design and Construction Tunnel Redundancy program. They said the MWRA provides wholesale water and sewer services to more than 3.1 million people and more than 5,500 industrial users in 61 Massachusetts communities.
The authority’s primary mission is to modernize the area’s water and sewer systems and clean up Boston Harbor. Other priorities are to oversee major capital programs to repair and upgrade the systems, promote water conservation and plan for the future to meet growing demand for water and sewer services. The two provided a history of water transmission systems in Massachusetts, dating back to the Cochituate Aqueduct in 1840s through to the MetroWest water supply tunnel in 2003.
They discussed the damage done and repairs needed when a water main broke in May 2010. After a surface pipe burst, more than 80 million gallons of potable water was discharged to the Charles River before the flow was shut off. The Hultman Aqueduct was shut down for repair and was unable to be used as a backup. A state of emergency was put in place, and about two million people were told to boil their water. Many manufacturers, businesses and restaurants had to be closed until emergency repairs were made. The repairs took two days to complete, but the cost amounted to about $208 million per day for businesses and $102 million per day for residents.
So there is critical need for redundancy in the Metropolitan tunnel system. Valve reliability for the Metropolitan tunnels is a concern, Murtagh and Brandon said. Without the ability to close and then reopen valves, there is no way to isolate a portion of the tunnel system. Many valves need to be replaced, they said, that cannot happen because the City Tunnel would need to be shut down while the valves are being replaced.
One alternative to gain redundancy in the city’s water tunnel system involves building two tunnels. The Northern Tunnel would 7.2 km (4.5 miles) long and would connect to the midpoint of the WASM in the Waltham/Belmont areas. The Southern Tunnel would be 15 km (9.5 miles) long and would connect with Shaft 7C. Together, the project 17-23 years to complete, they said.
This alternative would meet several objectives. It would provide redundancy for the entire Metropolitan tunnel system. It would also provide normal water service and fire protection if the existing tunnel system is out of service. It would be designed to meet highday demand, with no seasonal restrictions. And the alternative provides the ability to perform maintenance on existing tunnels year-round.
Update on the State of California Waterfix Tunnel Program. Sergio Valles is intermin chief engineer for California’s Waterfix program. The Sacremento/San Joaquin Bay Delta region near Sacramento is the hub of California’s water supplies, Valles said. It is a highly altered and highly studied area. Some areas in the region are 100-percent dependent on Bay-Delta supplies and critical to the state’s population and economy.
California Waterfix is important to the state, he said. Twenty-five million people rely on water from the Bay- Delta region from San Francisco to San Diego. More than 1,214,100 ha (3 million acres) of farmland rely on water from the region, and Delta fish and wildlife depend on a healthy Delta ecosystem.
Waterfix is proposing to drive two water transmission tunnels in the region to keep up the state’s increasing needs for water. Each of the tunnels will be 50 km (30 miles) long and 46 m (150 ft) below grade, he said. Concrete liners 0.6-m (2-ft) thick will be used and a pressurized face tunnel boring machine will bore an excavated diameter of14 m (45 ft) with a 12 m (40-ft) internal diameter.
More than 700,000 segments will be transported by barge and truck. More than 849,510 m3 (30 million cu yd) of reusable tunnel material will be moved. About 141,585 m3 (6 million cu yd) of concrete will be needed, and more than 200 MW of power will be required to drive the TBM. The overall cost will be about $16.7 billion, including $401 million in environmental mitigation costs and $16.33 billion in conveyance system costs.
Register for RETC
The Rapid Excavation and Tunneling Conference is set for June 16-19, 2019 in Chicago, IL. This is another event for professionals in the tunneling and underground construction industry to get together, learn from their peers and renew old friendships. Register at www.smenet.org.