By Lahne Mattas-Curry
No where to run: stormwater has no place to go but the sewer.
In the first post of my series on EPA water research, I gave a little history lesson and introduced green infrastructure. This week, we’re going to focus on the cost of combined sewer systems—to our health, our environment and even our economy.
There are hundreds of cities across the country that have combined sewer systems. For example, in New York City, more than 27 billion gallons of raw sewage and polluted stormwater discharge out of 460 combined sewer overflows into the New York Harbor alone each year. Think about all the impermeable surfaces in the city: sidewalks, streets, roofs, patios. It’s a concrete jungle.
To manage stormwater—and set up scenarios to see the impact of development—EPA scientists are developing the Stormwater Calculator that estimates the annual amount of stormwater runoff from a specific site and provides city planners, developers, and property owners a way to calculate the result of specific actions on our waterways. The online tool will be available later this fall.
As stormwater flows over the surface of your property, driveways, parking lots, roofs, etc, it picks up lots of sediments, such as animal droppings, tire residue, motor oil, brake dust, deicing compounds (in the winter), fertilizers, pesticides, trash, heavy metals and other pollutants and carries them to the nearest storm drain.
Obviously, there are things that cities can do to help reduce stormwater run off, and the steep price tag that goes with the cost of separating the combined sewer systems.
For example, in Omaha, the city is testing green infrastructure throughout the city to help reduce the $1.7 billion sewer system separation project. EPA scientists are testing and monitoring soils in Omaha, and other cities such as Cleveland and Cincinnati, to measure how successful green infrastructure is at keeping the combined sewer overflows to a minimum.
Cities like Omaha are looking for ways to use green infrastructure to reduce stormwater costs.
There are steps you can take too.
According to the University of Nebraska, for every 1,000 square feet of impermeable surface on your property, every 1 inch of rainfall generates approximately 626 gallons of water. If you add two 55 gallon rain barrels to your property, you now have water to irrigate your gardens. Add a rain garden, and you probably take care of much of the excess. Now, rain is absorbed back into our aquifers instead of rushing into the nearest storm drain, keeping waterways clean and ecosystems functioning.
Many states and counties subsidize the installation of green infrastructure on property, so check with your county and state government. It’s worth it to make sure we have clean water for generations to come.
About the Author: Known around the office as “AguaGirl,” Lahne Mattas-Curry works with EPA’s Safe and Sustainable Water Resources team and communicates water research to anyone who will listen or read her blog posts.