Harvey: Investing In Green Infrastructure Offers Triple Benefits: Reduces Flooding, Nutrient, Sediment Runoff
Now Tropical Depression Harvey is another opportunity to remind public officials that investing in green infrastructure yields triple the benefits-- reducing stormwater flooding, nutrient and sediment reduction-- over single purpose solutions.
Green infrastructure includes floodplain restoration, absorbent drainage swales and ponds, forested stream buffers, parks and open spaces, porous pavement, rain gardens and other on-farm conservation practices.
Here are just a few articles that explain the triple benefits of green infrastructure--
Green infrastructure (GI) is the use of plants and absorption techniques to capture and transport precipitation and stormwater runoff. It is the opposite of traditional grey infrastructure, which uses drains, pipes, and ditches to take stormwater to a treatment plant or outfall in a stream.
As the rain falls, many communities across the country worry about the very real possibility of flooding. According to the U.S. Environmental Protection Agency, heavy downpours have increased in frequency and intensity over the last 50 years, and are expected to become even more intense as a result of climate change.
This raises the likelihood of flooding.
The EPA also notes that the average 100-year floodplain is projected to grow by 45 percent by 2100, and the annual damages from flooding may increase by as much as $750 million.
In LandStudies’ trendsetting publication, Economic Ecology: Floodplain Restoration, twelve Pennsylvania case studies demonstrate the economic rewards of tackling environmental issues on a regional scale, specifically through floodplain restoration.
Municipalities throughout the Commonwealth can benefit from the concepts of Economic Ecology.
At the beginning of the year, LandStudies and CS Davidson launched a campaign to make more township and borough managers, parks and rec directors, and elected officials aware of the ways that Economic Ecology can--
-- Increase property values, particularly around parks and other greenspaces;
-- Protect property and infrastructure from flooding;
-- Improve water quality in local streams and rivers; and
-- Enhance aesthetic values that make people linger in an area longer.
So how to do municipalities begin to reduce stormwater runoff and the pollution associated with it?
Well, they can increase the size of underground pipes, holding tanks, and the capacity of their sewage treatment plants which would cost millions of dollars. Or, they can consider some greener and cheaper solutions in concert with the grey infrastructure of pipes and holding tanks.
One of those green and cheap solutions involves the planting of large canopy trees. A great deal of research by the USDA Forest Service and others has shown that trees and forests reduce stormwater runoff and pollution in several ways.
Removing the sediment, creating a 16-acre system of low-profile riparian vegetation areas on the site and restoring the stream to its original floodplain eliminated streambank erosion that carried tons of sediment and nutrients from the segment of the Creek on the Site.
It also reduced stormwater peak flows along the stream, allowed for groundwater recharge, provided wildlife habitat areas and more usable commercial space on the site versus using traditional methods.
And, the project was completed without public money.
Parks and other open spaces (rights-of-way, along streets, parking lot medians, etc.) are the most ideal places in a municipality to generate a variety of long-term economic, ecological, and community benefits,” such as water quality and quantity improvement and infrastructure protection.
Incorporating green infrastructure for stormwater management into parks provides a community with two major benefits: meeting regulatory requirements, such as those related to MS4 permits, and enhancing a public asset for the betterment of the entire community.
Any well-established park will have facilities in need of renovation or retrofit over the years, offering opportunities to manage stormwater “naturally” on-site. Parks yet to be built can have green infrastructure designed and installed from the beginning, reducing costs.
Click Here for new EPA Guide To Green Infrastructure in Parks To Manage Stormwater.
“After a cloud burst, the stream would be chocolate milk,” Hurst lamented. “I remember my dad being so upset and saying, ‘That’s our topsoil.’”
Today, Hurst and his neighbors have all put in buffers and undertaken other farming practices to improve their soil, such as contour farming—farming perpendicular to the slope of the land to keep stormwater from stripping the field —cover crops and no-till practices, which cut down on maintenance costs and encourage beneficial organisms to thrive.
After a rainfall, they see a much more mild change in the rise and fall of their shared stream as the soil around it soaks up the groundwater.
Healthy floodplains have more stable streams, which protect downstream infrastructure, such as bridges and cabins.
In the past, people “channelized” streams, straightening out their pathway and moving floodwater downstream quickly. This has caused problems downstream, removing water from the water table, causing higher flood events and more erosion.
Many of our current streams have been disconnected from their floodplains by either channelizing or by legacy sediments, silt, and sand left behind from mill dams during colonial times.
The addition of large woody material to streams can slow the water and force it onto the floodplain, while woody material on the floodplain slows the flood water even more allowing sediment to drop out. The water stays in the floodplain longer, allowing for infiltration and erosion reduction.
Other Examples Of Green Infrastructure Innovative
The Wyoming Valley Sanitary Authority is leading more than 30 municipalities in an effort to use green infrastructure to comply with MS4 Stormwater Pollution Prevention Requirements that will reduce compliance costs by an estimated 50 percent.
In Lycoming County they have adopted their own local nutrient credit trading program to promote cost effective solutions to nutrient and sediment reduction.
York County has also taken a county-wide approach and created an Integrated Water Resources Plan to comply with not only MS4 Stormwater requirements, but to comply with all Chesapeake Bay and local TMDL impaired stream nutrient and sediment reductions.
The City of Lancaster established a Green Infrastructure Program to install stormwater pollution reduction measures throughout the City. A similar green infrastructure plan is being finalized by the Capital Region Water Authority for the City of Harrisburg.
The Philadelphia Water Department’s Green City, Clean Waters Program is now into its sixth year of implementing its green infrastructure program and the City of Pittsburgh is now proposing its own green infrastructure program along with the 3 Rivers Wet Weather Project to promote green infrastructure on a regional basis.
What do all these approaches have in common? Low-tech, cost-effective best management practices that work to prevent pollution from stormwater and reduce nutrients and sediment getting into our rivers and streams-- triple benefits.
For much more on this topic, visit the PA Environment Digest website, Search “Green Infrastructure” under “Subjects.”
[Posted: August 28, 2017]
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