Using Green Infrastructure to Stop Combined Sewer Overflows

The Canadian environmental organization Ecojustice released a report on Tuesday focusing on preventing rainwater from entering our sewer systems. Most big cities had their sewer systems built in the early 1900's. When they were built raw sewage and storm water used the same sewer, this is called a Combined Sewer. Most are serving larger populations than was ever originally intended, so as a consequence, when it rains they overflow and release sewage into our waterways.

Though the report focuses primarily on Ontario, the suggestions of green infrastructure which they define as “an interconnected network of natural areas that maintain natural ecological processes,” can be applied anywhere. Many of the solutions presented in the report are alternatives to hard infrastructure solutions that are often prohibitive due to high costs. An example of a costly hard infrastructure solution is overhauling a large cities' sewer system. It gets real expensive real fast.

Another problem identified in the report is Canada's lack of public reporting. In Michigan, the Michigan Department of Environmental Quality (MDEQ) reports every Combined Sewer Overflow (CSO) that happens. That is not the case in Ontario. The Ontario Ministry of the Environment (MOE) collects some information on CSOs but the data is often inconsistent and rarely provides a full and accurate picture of what is going on. Some of the federal and provincial government data does not even contain volumes for the amount of the CSO. This distorts the overall effect of CSOs on the Great Lakes since it is somewhat of a mystery of the total number of sewage entering the Great Lakes.

A 2006 report by Ecojustice graded Windsor the third worst in CSOs for major cities in the Great Lakes basin. So all we really know is that the problem is bad. We can only guess just how bad it is.

The Ecojustice report is using an innovative way of tackling the problem since it aims at a more direct solution of limiting the amount of water that gets into the sewer systems, and provides options that are affordable and practical and provide aesthetic value to communities.

Many of the solutions suggested are beginning to be implemented in many big cities across the country such as Chicago, Toronto, and Portland that have implemented on a large scale many of the Ecojustice suggestions such as green rooftops, rain barrels, permeable sidewalks and roads, and bio-retention areas. The aim of all those measures is to "get the rain out of the drain" as the report succinctly put it.

Even locally people are starting to implement some of these suggestions as well. The Detroit Free Press recently reported that a green roof is being constructed in Auburn Hills over the gun range at the Public Safety Department.

The report provides several case studies of what cities are doing to reduce water from overwhelming sewer systems and water treatment plants and leading to CSOs.

Green Cities, Great Lakes: The Green Infrastructure Report