5. Lake Mead Third Water Intake
If you’ve visited the Hoover Dam in recent years, you’ve noticed the “bathtub ring” around Lake Mead, the discoloration in the shoreline left as the lake’s water level has dropped precipitously. But what makes an interesting photo opportunity for tourists could spell trouble for residents of Las Vegas and other towns in the region that rely on the lake for drinking water. Officials are concerned that a few more years of drought could drop the lake’s level below one of the two existing intakes in Lake Mead. As a result, construction began in 2009 on a third intake, some 200 feet deeper than the existing intakes. The $800-million project poses numerous challenges in drilling a 3-mile-long, 23-foot-tall tunnel through solid rock 600 feet under the lake to the water-pumping station. At one point, hundreds of cement trucks had to be carried out to the middle of the lake on barges. Another challenge arose in mid-2010, when work crews struck a geographic fault, flooding the tunnel with water and muck. That tunnel had to be abandoned, and work started in another direction. Work was halted again in June 2012 when the tunnel claimed its first victim. Barring further setbacks, work on Lake Mead’s “third straw” should be complete by 2014.
4. San Francisco Central Subway Tunnel
You have to admire the optimism of San Francisco officials, who in June 2012 started work on a short (1.6-mile) but expensive ($1.6 billion) subway tunnel to Chinatown. The catch: the federal government has not yet approved its share of funding, $942 million. It’s expected to be approved by Congress in fall 2012, but the issue is far from settled. Even some former city officials contend the project is too expensive and would be underutilized, and are lobbying to kill the federal funding. The tunnel is scheduled to open in 2018.
3. Seattle’s SR 99 Tunnel
Seattle’s Alaskan Way Viaduct, a double-deck highway along the city’s downtown waterfront, was an engineering marvel when it opened in 1953. Unfortunately, the powerful 2001 Nisqually earthquake weakened the structure’s foundation to the point that another severe quake could cause collapse (check out this link on the state of Washington’s transportation blog for a computer simulation of a collapse that looks like something out of a disaster flick). The solution? A $2 billion project to run Highway SR 99 under downtown Seattle. Prep work on the 2-mile tunnel began in early 2012, and the project should be open to traffic by late 2015.
2. Chicago Deep Tunnel
Chicago has long had a problem with sewage overflowing into Lake Michigan, source of the city’s drinking water. So in the mid-1970s, the city launched the Chicago Deep Tunnel project. More than 30 years, and $3 billion later, workers had bored an amazing 109-mile network of tunnels hundreds of feet under the Windy City. It was such a momentous achievement, English and French engineers visited the project, then adopted the same technology to build the famous Chunnel between the two countries. Although the network of tunnels under Chicago is complete, work continues on reservoirs to store the sewage, with completion expected in 2029. Now for the bad news: some researchers predict that even this huge tunnel system isn’t sufficient, as rainfall has increased in the region in recent years. Already, heavy rainstorms in 2008 and 2010 produced disastrous results — the city actually dumped more sewage into the great lake than before the tunnels were operational.
1. New York City Water Tunnel No. 3
This project is so massive in scope, time and money (a cost of up to $6 billion) that it boggles the mind. New York City politicians first authorized a third water tunnel for the city in 1954, and construction began on the 60-mile pipeline in 1970. Plans call for the tunnel to be completed in 2020, more than 65 years after its conception. The tunnel stretches from the Hillview Reservoir in Yonkers and runs as deep as 800 feet beneath the surface of four of the city’s five boroughs. Parts of the tunnel that are finished have already been put into service, but when completed, the tunnel will for the first time allow the closure of the city’s two earlier water tunnels, built in 1917 and 1936, for inspection and repair. The construction has claimed 24 lives, including a child who was killed while playing on the job site. By the way, the one borough the tunnel doesn’t cross, Staten Island, launched its own $250 million water main project in spring 2012.
More: Midwestern Cities Digging Deep
Both Cleveland ($200 million) and Indianapolis ($180 million) began major tunnel projects in 2012 designed to solve long-standing issues with sewage. Cincinnati is planning a similar project that could run more than a quarter-billion dollars.