Cleaning Up an Effluent SocietyAdam Aston
What's driving Chicago to pour $3 billion into a 109-mile network of tunnels and reservoirs hacked out of the limestone underlying the Windy City? It's the same fetid force that spurred Los Angeles voters to O.K. a $500 million bond last November. Construction titans and big-box retailers are getting more serious about it, too. It's causing thousands of other U.S. cities and companies to yank up manhole covers and storm grates and take a closer look at the witches' brew of garbage, hydrocarbons, and bacteria that flows down curbside drains and eventually into local waters.
Under foot and out of sight, those conduits are a growing problem. They empty untreated stormwater into rivers and lakes. This water can, at its worse, "kill fish and wildlife, close beaches, and threaten human health," explains Steve Fleischli, executive director of Waterkeeper Alliance, a nonprofit watchdog group based in Irvington, N.Y.
That's why the U.S. Environmental Protection Agency has made cleaning up stormwater a must-do for the nation's municipalities. The EPA Web site describes storm runoff as "one of the most significant sources of water pollution in the nation, comparable to contamination from industrial and sewage sources."
By the end of 2008, EPA rules say that cities with population of more than 10,000 must have a plan in place to stem the flow of debris and contaminants from curbside into local waterways. The rule has unleashed a wave of spending on everything from megascale engineering projects like Chicago's Deep Tunnel to innovative drain drop-ins that cleanse the water that passes through it.
Stormwater can pollute, sicken, and even kill. First, it's highly polluted from the get-go. While rain water may fall from the sky clean, it becomes foul the instant it hits the street. The contaminants include an estimated 1 million gallons of dissolved hydrocarbons -- oil and gas dripping from the nation's 200 million-plus vehicles -- per year, as a toxic stew of animal and human fecal bacteria, rubbish, and traces of heavy metals, pesticides, and herbicides, particularly in suburban and rural areas.
What's more, many storm systems flow directly to waterways and lakes. Tom Leary, stormwater program officer at the City of Long Beach's Public Works Dept., explains that when it rains in the Los Angeles/Long Beach area, anything within the 875-square-mile Los Angeles River drainage area "is flushed into the sewers and eventually into the river." Last year that included some 12,000 tons of rubbish that washed up on city beaches.
BAD BEACH DAYS.
Sewage spills pose a related, more complicated problem. Many cities linked their storm drains to sewage pipes -- in part or in whole -- because of the hazard posed by untreated stormwater. The idea: By passing storm runoff through sewage treatment plants, rainwater can be cleared of garbage and toxins. And this works when the pipes can handle the flow.
Yet in cases when a heavy rain fills up both pipe networks, they can back up and flood city streets with sewage-tainted water, as used to happen in Chicago. The contaminated water is then forced into nearby rivers or lakes. Sewage spills can spike bacterial (fecal coliform) counts for days, exposing bathers to cholera and other diseases. Along California's coast, for example, "Closed Beach" days have been common in recent years because of health risks posed by sewage plumes.
Big companies are in the firing line, too. Construction projects and multi-acre parking lots are particularly serious sources of what the EPA describes as "non-point pollution" flowing into sewers. The agency has lately been turning up the heat on big-box retailers and large property developers, says Fleischli. Together with the U.S. Justice Dept. and a number of states, the EPA reached a settlement with Wal-Mart Stores (WMT) in 2004 for violating the Clean Water Act during store construction. The retailer agreed to pay a $3.1 million civil penalty and to reduce tainted runoff from its sites.
Chicago's approach has been to build what amounts to a very big holding tank for its sewage and rain water. Formally known as the Tunnel and Reservoir Project, the EPA-funded network was begun in 1974 and is made up of subterranean tunnels, many the width of a locomotive, connected to a series of concrete caverns. By storing wastewater until it can be processed by sewage treatment plants, the largely completed system is already helping to make Chicago area waters cleaner.
Once infamous for its lifeless, inky, and occasionally even flammable water quality, the Chicago River has been resurrected with the return of some 50 species of fish, along with canoeists and riverside cafés, if not swimmers quite yet. You can see the progress at this slide show.
Compared to Chicago's big dig, Norwalk (Conn.) has taken a micro approach. Rather than tear up its streets, the city turned to privately-held AbTech Industries Inc. to buy a high-tech filter that can be dropped into the existing stormwater drains. AbTech's Ultra Urban Filter (UUF) liners are made of a patented polymer that lets water pass through, but bonds permanently with oil, PCBs, and other toxins, while also catching more common trash. When treated with a proprietary anti-bacterial, nontoxic coating, the sponges can also zap harmful bacteria as water passes through the popcorn-like material. In addition to routing debris removal, typically done with storm sewers, the UUF's anti-bacterial and oil-trapping capacity lasts about two years.
Other cities and companies are following suit. Long Beach, for example, is using a "treatment train" combining UUFs, garbage nets, and a handful of mechanical separators that spin wastewater to separate debris. Alternatives include more costly chlorination, ozonation, and/or power-hungry devices that use ultraviolet light to sanitize water as it passes through.
Yet, none combine antibacterial properties with the ability to drop them into existing storm drains, with a minimum of costly construction, explains Glenn Rink, president and chief executive of AbTech. At about $1,000 per drain, UUFs can help a city clean up its waterways, for thousands or millions of dollars, rather than billions. With over 275 UUFs in key areas around Norwalk paid for by a $500,000 EPA grant, the filters are proving to remove, on average, 75% of harmful bacteria, and up to 99.9%.
With the EPA's deadline drawing nigh, pressure to clean up stormwater runoff is just beginning to rise. Nationwide, the number of roadside catch basins -- in cities and rural areas -- is estimated to be over 5 million. Cleaning them all is a Olympian task, but you can do your own small part: Rather than toss that cigarette butt or dog poop down a sewer grate, look for a trash can instead.