The tunneling industry is thriving in the Midwest; water and wastewater needs are providing vast amounts of work across the region. In particular, cities are updating the ageing sewer systems – many states are making improvements to reduce or eliminate combined sewage overflow (CSO) problems found in older systems predating the Clean Water Act.

"We’re responding to North America’s ageing infrastructure," says David Egger, director of Black & Veatch’s heavy civil group. "We have the deterioration of infrastructure that was put in place in the 1920s or before and that’s driving the demand for both conventional tunneling as well as for some of the newer technologies such as mircotunneling. There’s also the water scarcity element – there are a number of schemes all the way from Texas and Oklahoma to South Dakota involving water transfers."

Several multi-million dollar water and wastewater project contracts were tendered last year and the year before. In Ohio and Indiana the market is particularly strong, and Egger says there is still high demand for these projects: "The market is looking very, very rosy. In fact, if we think about now until the year 2020 I think there will be more than one, probably about three, projects rolling out like the Deep Rock Connector Tunnel in Indianapolis, which began construction last year."

Egger says that it is a common misconception that the Midwest has more land to build roads and does not have the existing public transport to require tunnels. "People like to think about the Midwest cities being less dense than coastal cities and that there’s more land and space," Egger explains. "But that’s really no longer true. A big driver has become density."

In addition, the East North Central region of the Midwest, which includes Michigan, Ohio, Indiana, Illinois, and Wisconsin, are also known as the ‘Great Lake States’, and the projects often contend with unusual obstacles. "Many sites are by large rivers such as the Mississippi and the Ohio River," says Egger." The tunneling here can be very challenging when we get down to these rivers because of floods. The Mississippi has flood events, the water rises and it really plays the devil with working around constructing shafts near rivers. It gets very complicated."

It is the region’s particularly difficult terrain that makes many of these projects especially challenging. "A lot of tunnels in this region are in rock," says Egger. "A lot of other areas in the US, particularly areas that are coastal, get into soft ground tunneling. In the Midwest, because of the way of the land and the way it was formed, rock tunneling is more prevalent. We have developed great knowledge in the region around dealing with karst formation, which is when you have rock that has been solutioned over time by water and it leaves voids, and that’s bad as nobody likes surprises. We’ve spent a lot of time in the Midwest learning how to deal with karstic ground. This is something unique that we’re bringing to the wider world of tunneling."

Ohio
Kenny/Obayashi JV, the contractors of the OSIS Augmentation Relief Sewer tunnel (OARS) in Columbus, Ohio, are up against the difficult combination of hard rock with high ground water pressures. The tunnel will be approximately 170ft (52m) below ground and the overall length of the tunnel is just less than 4.5 miles (7km). The sewer tunnel will intercept wet weather overflows and carry the flows to the city’s Jackson Pike and Southerly wastewater treatment plants. "The geology the OARS team are facing is incredibly complex," says Egger. "The TBM mobilised is absolutely state of the art to deal with some of these karstic formations."

In addition, two more tunnels on the east and west side of Colombus — the 13-mile (21km) Alum Creek Relief Tunnel and the 11-mile (18km) Olentangy Relief Tunnel — will be constructed to relieve sanitary sewer overflows in 2014 and 2018 respectively.

The Northeast Ohio Regional Sewer District has its USD 3bn Project Clean Lake, a 25-year program seeing construction of seven tunnels, ranging from two to five miles (three to 8km) in length. A McNally-Kiewit joint venture secured a USD 198.6M contract in December 2010 to excavate the 17,750ft (5.5km) Euclid Creek Storage Tunnel with a 24ft (7m) diameter by TBM, which is being loaded and transported to the project site as TTNA goes to press. The tunnel will be 18,000ft (5,476m) long and have the capacity to hold 70M gallons of combined stormwater and wastewater. The project is due to be completed in 2015.

In Cincinnati, Ohio, Black & Veatch have been selected to design the Lower Mill Creek tunnel, a USD 244M deep rock project to combat sewer and stormwater overflows for the Metropolitan Sewer District of Greater Cincinnati. The 1.2 mile (1.9km) tunnel will be 30ft (9m) in diameter and the contract includes a pump station and enhanced high-rate treatment facility in Cincinnati. Following completion of the project in 2018, the tunnel is expected to reduce CSOs by 85 percent and eliminate all sanitary sewer overflows.

"The Lower Mill Creek tunnel is in the planning and design stage right now," says Egger. "It’s a very interesting project because the tunnel itself is being built behind a barrier dam up to the Ohio River. The Ohio River is affected by floods and [during a rain event] might rise from [a depth of] 32ft to 50ft (10 to 15m). So to protect the city they had to barrier dam it and the tunnel is being built behind that, which is very unusual."

Missouri
In Kansas City, Missouri, work is underway on a tunnel and pipeline to carry as much as 180M gallons per day of treated wastewater by gravity nearly two miles (3km) from Johnson County Wastewater’s Mill Creek Wastewater Plan in Shawnee, Kansas, to a discharge point downstream of a water intake on the Kansas River.

The tunnel will be 110 – 180ft (33.5 – 55m), in which a 96in (2,438mm) diameter fibreglass-reinforced pipe will be grouted into place.

The project is due to be completed in late 2013. "It’s interesting as it’s a good illustration of outfall tunneling, another key trend in the Midwest," adds Egger.

Illinois
Then there is the Deep Tunnel Project in Chicago, Illinois. The project includes over 100 miles (160km) of tunnel mostly 30ft (9m) plus in diameter. "The project began in the late 1970s and we’re coming to the end of it," says Egger. "There’s still some active tunnel working going on, to do with important reservoirs in particular. It’s neat because we’re seeing a tunnel programme that has lasted longer than one man’s professional lifetime coming to an end."

Last year, the new water intake tunnel beneath the Missouri River, as part of a project to increase the capacity of Jefferson City’s water supply, completed. The 16- month long construction project was designed by Black & Veatch and executed by contractor Reynolds, to upgrade the water pipelines and pumping station that deliver water from the Missouri River to the water treatment plant, improving the reliability of water delivery.

The project replaced water infrastructure that was 50 to 120 years old.

In addition to the new pumping station, the construction team of W.L. Hailey installed two 20in (508mm) diameter pipelines that are 30ft (9m) deeper and extend 80ft (24m) further into the river than the previous 1960s structure.

While the tunneling industry has been penetrating cities throughout the Midwest, Egger says that it is local contractors winning big-scale work and are scarcely having to look outside the region. "We’re very fortunate in the Midwest; we’re home to some global scale tunnel contractors," explains Egger. "The companies are growing and beginning to go to places they haven’t been before. We also see some home-grown contractors, people who may have had tunneling as a skill set, expanding it into a full-blown competency. We’re not seeing many outside contractors coming here. There’s always been enough of a skill set to handle most of the demand – nobody is going out of business. In fact, we’re seeing companies growing and expanding into other regions of the country."

While the market continues to flourish, Egger explains that this is, in part, due to tunneling being a much more accepted and widely understood construction technology. "I used to tell people that I thought this was about a USD 3bn market here in the US. Well, I think it is double that now," Egger says. "It has been a two to three billion dollar a year market for a while now, but it’s much larger than that simply because the technology has improved, the clients have become more accepting of it and there is more need for it."

Call to Indianapolis
The Midwest is playing host to the 2012 North American Tunneling Conference in June. The conference will include presentations on local projects and a visit to the Martin Marietta North Indianapolis mine and quarry.