Imagine sewage, sludge, and street pollutants mixed with billions of gallons of water flooding literally thousands of basements, pouring along streets, backing up in buildings, and eventually ending up in the community's drinking water source.
This isn't the flooded streets of Pakistan. This is Chicago, Illinois, this past summer when almost 7 inches of rain dumped on parts of the city. Literally trillions of gallons of water fell on the concrete and asphalt urban scape in a two-day period. The city's combined sanitary/storm sewer system was overwhelmed; it overflowed, thousands of basements flooded, and a good portion of the polluted mess eventually ended up in the Chicago River and Lake Michigan.
This isn't a once in a lifetime isolated occurrence, or a Chicago-only event. This is any one of hundreds of other cities in the United States, too, where despite a vast infrastructure of sewers, flood protection systems, and more, too much rain in too short a period of time regularly overwhelms sewer systems, floods homes and businesses, fouls waterways, and eventually taints source water supplies. (For more, http://www.epa.gov/ednnrmrl/researchtopics/wetweatherflow/cso.pdf)
Stormwater runoff and the pollution associated with it--sometimes to the point of overflowing sewers-- known as Combined Sewer Overflows or Sanitary Sewer Overflows--is a serious health threat that cities nationwide regularly face. It's not just untreated or partially treated sewage and nonpoint source pollution in the toxic mess either. In towns like Seattle, Washington, for example, saltwater adds to the mix creating additional concerns, says architect and urban and regional planner Daniel E. Williams, FAIA. The salt in the water can decompose steel and impact the structural integrity of buildings, adds Williams, also author of Sustainable Design: Ecology, Architecture and Planning (Wiley, 2007).
Typical solutions to overflows generally involve big-dollar infrastructure investments. But Chicago meteorologist Amy Freeze has an idea for a new approach to help contribute to the solution to combined sewer overflow and subsequent water pollution problems not only in Chicago, but across the country. Chief meteorologist for Fox Chicago, Freeze hopes to start a voluntary community-based Stormwater Action Alert Program designed to notify consumers and ask them to cut back on water usage when conditions are right for a heavy rain event that could overwhelm sewers, cause flooding, and ultimately degrade water quality. The idea is that with less wastewater in the sewers at the time of a big storm, the sewers are more likely to have capacity to handle water from the storm.
"The community-based initiative would be similar to the already successful national air quality initiative, "Partners for Clean Air," says Freeze. "With water, if before the storm occurs, we can limit the volume of water in our sewers, it will go a long way toward improving the quality of our source water. It may not immediately solve the problem, but we have to start somewhere," says Freeze. She envisions Chicago as a starting point for the alert system, and then hopefully grow it in scope.
New England environmental analyst Clair Ryan is intrigued by the idea of an early warning system for potential sewer overflows. But, she isn't sold on how effective it could be. Ryan specializes in nonpoint source (general water runoff) and stormwater for the Massachusetts-based New England Interstate Water Pollution Control Commission (http://www.neiwpcc.org). "Part of the problem is that for some Eastern cities, the threshold for the amount of water that has to fall for a combined sewer overflow is very small. Even if people stopped using as much water, it's the sewage that's already in the system that gets washed out in a CSO. I don't think an individual is going to have a large impact on CSOs or SSOs. You really have to get an entire community interested, then cumulatively there is a possibility of reducing at least the duration of the sewer overflow," she adds.
"The order of magnitude is so huge when you have a major rain event," agrees Williams, "the only way to make a difference is if you have a very large urban forum." The early warning system, though, is one part of a multi-faceted solution that includes planning and patterning neighborhoods with water issues in mind, says Williams. The alert program is about getting the community to understand that where water is concerned one thing has an impact on another.
"If there's awareness, the action will eventually come," adds Freeze.
To learn more about rain, stormwater, and water pollution check out the U.S. Environmental Protection Agency's National Pollution Discharge Elimination System web site (http://cfpub.epa.gov/npdes/home.cfm?program_id=5)