March 01, 2010

Re-Inventing Rainwater Management

Ran across this study today (pdf doc): Re-Inventing Rainwater Management: A Strategy to Protect Health and Restore Nature in the Capital Region by the  Environmental Law Centre at the University of Victoria. While I have yet to read all of it, it appears to be an excellent take on issues that streamkeepers in Burnaby and all over BC have been concerned about for years. An excerpt from the introduction to the problem:

We don't normally think of rainfall as pollution. However, over the last 150 years we have built cities in a way that transforms rainwater into an agent of considerable environmental harm: urban stormwater runoff.

Changing pristine rainwater into pollution occurs in stages. The first step is the creation of pollutants from driving and fixing cars, using chemicals on houses and yards, and commercial and industrial processes. Heavy metals, PCBs, oils, grease, antifreeze, solvents, pesticides, herbicides, fertilizers, paint chips, PAHs, road salt, and detergents fall to the ground across the urban landscape.

The second step involves our construction of impervious surfaces such as roofs, paved streets, sidewalks, and parking lots. As a city develops, the vegetation and natural soils that absorb and filter rainwater are replaced by impervious surfaces. When we pave over nature's absorption and filtration system, the next heavy rain sweeps across the landscape's hard surfaces picking up pollutants.

In the final step, the storm sewer system rapidly conveys all this polluted water to the nearest water body and flushes it at high speed into a sensitive aquatic ecosystem. In addition to the pollutants from the landscape, the water often contains paint and motor oil that people have dumped into the storm sewer. To make things worse, in older municipalities, this stormwater often contains sanitary sewage.

Posted by Paul at March 1, 2010 08:32 PM