Combined sewer overflows are becoming a serious problem for more and more cities. Davenport, Iowa, is currently looking at increasing sewer fees to fund studies and repairs to its infrastructure to improve its CSO situation—but at different times, it might be any of dozens of cities in the headlines for similar reasons.
The reasons for the CSOs are diverse. Many older cities have combined sanitary and separate sewer systems that route everything to wastewater treatment plants, which have too little capacity to handle the current load; increasing amounts of impervious surface in urban areas send more stormwater runoff into the sewer system; and separation of combined sewer lines is disruptive and very, very expensive. Uncontrolled CSOs have led to legal action and consent decrees in many areas.
There are diverse solutions as well. Because building additional treatment plants or wholesale separation of the sanitary and storm sewers are usually prohibitively expensive options, many regions are looking to divert stormwater runoff or at least to slow the rate at which it enters the system. Green infrastructure—infiltrating more of the stormwater—has become a popular solution; adding swales and pervious pavement, disconnecting roof downspouts, and other measures can be done little by little and requires a steady—but less overwhelming—investment than building a new treatment plant. The trick is to determine how much green infrastructure is needed and how effective it will be in the long term.
An article in Stormwater’s upcoming March/April 2012 issue discusses various options Cincinnati is considering, including traditional and green infrastructure BMPs as well as separation of portions of the combined sewer system. This article looks at how New York City, Chicago, Kansas City, and Portland, Oregon, are combining green and grey infrastructure to try to affordably get a handle on the problem.
Have studies been done in your area on the effectiveness of green infrastructure on CSOs?
Upcoming Forester University Webinars
January 26th, 2012
5 Steps to Creating a Successful Public Outreach Campaign
Change starts with people. Whether your focus is stormwater pollution, energy conservation, pavement restoration, or recycling, a successful public outreach campaign resonates with your target audience and leads to long-lasting behavior change. Join Erica Hooper of SGA to explore a proven 5-step approach to crafting a successful outreach campaign based on real-world examples of the good, the bad, and the ugly. Read more…
February 2nd, 2012
Advanced Stormwater Treatment: Dissolved Pollutants
How effective are your stormwater treatments in capturing dissolved loads? With an average of 45% of the phosphorus load and up to 50% of the metal load transported through treatment practices to receiving waters in dissolved form, advanced treatment is imperative. Join Andrew Erickson to explore cost-effective, field-tested methods to capture stormwater dissolved pollutants and optimize stormwater treatment performance. We’ll explore several field applications and data demonstrating significant improvements in dissolved pollutant fraction capture. Read More...
February 9th, 2012
Differentiating & Monitoring Groundwater Plumes
Threatened by various plumes of mobile contaminants, urban potable groundwater resources require groundwater professionals to not only determine the source of individual plumes, but apportion the contributions of multiple sources within a composite plume. Join William G. Soukup, P.G. of Cornerstone Environmental Group LLC to discuss the analytical and interpretive techniques for differentiating plumes and their sources, as well as tips to improve long-term plume monitoring and management. Read More...