Low Impact Development: What It Is and Why We Want It

In the coming months WMEAC will be talking a lot about stormwater management issues in West Michigan: water pollution, excessive costs to maintain existing stormwater infrastructure, flooding, and sanitary sewage backups.

To help illustrate these problems, we will be posting images and video of critical cases as we find them throughout the rainy months of spring.  Our hope is to slowly expose the issue and help raise awareness for Low Impact Development strategies that could provide sustainable solutions for stormwater management.

LID is a stormwater management technique that aims to mimick a site’s predevelopment hydrology.  “Predevelopment” refers to the way North American land was before any settlers began to clear away vegetation for farming and housing.  “Hydrology” refers to the way water ebbs and flows in our environment, including in the atmosphere, on the earth’s surface, and below the earth’s surface.

Today, the landscape is drastically altered from the year 1800 or so, with the majority of native vegetation cleared and large amounts of surface paved that does not allow rainwater to soak into the ground.  Since rainwater is no longer able to soak into the ground, it “runs off” into our stormwater pipes, which convey it to streams, rivers, and lakes, destroying riverbanks and carrying with it a variety of pollutants.  LID techniques help solve this water pollution problem by imitating nature: allowing rainwater to soak into the ground close to where it lands.  Examples of LID techniques are rain gardens and rain barrels.

Water pollution is not the only problem LID helps solve.  In most cases, the practice is also more cost effective than conventional stormwater infrastructure, and can even reduce road construction (less traffic jams!).  Our cities currently manage run-off with a complicated system of stormwater sewers under our roads that is expensive to implement and maintain.  Using LID, we can save money through lower implementation and management costs for residents, business owners, and governments.  There are several examples of the cost-effectiveness of LID, and it is by no means an untested and unproven technology[1].  Savings of up to 80-percent have been seen through the use of LID techniques instead of conventional approaches for stormwater management.  Road construction often happens because there are necessary repairs or expansions of the stormwater system, not because repaving is needed, which in many cases is an expense that can be delayed in order to save money.  However, maintaining and expanding the piping under the road’s surface is an expense that cannot be delayed due to water pollution regulations and potential flooding damages.

LID can reduce and potentially eliminate instances of flooding, sanitary sewage backups, and other property damage due to poor stormwater management.  Flooding happens when our conventional stormwater systems fail to drain and carry away rainwater fast enough from our streets, public spaces, and private property.  The flooding will even cause sanitary sewage backups in some neighborhoods.  These headaches can be avoided by managing this stormwater in a way that works with nature, instead of against it.

[1] See: Reducing Stormwater Costs through Low Impact Development (LID) Strategies and Practices, USEPA, 2007  (http://www.epa.gov/owow/NPS/lid/costs07/), and the Low Impact Development Manual for Michigan, SEMCOG, 2008  (http://library.semcog.org/InmagicGenie/DocumentFolder/LIDManualWeb.pdf)

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