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Do I live in the Hinkson Creek Watershed? Report a Spill/ Poor Erosion Control
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Low Impact Development
Low Impact Development (LID) is a term for a group of techniques that will reduce the stormwater impact upon the surrounding landscape. LID techniques may impact the quantity of stormwater run-off, the quality of stormwater run-off, or both. LID has been around for a number of years, and is commonplace in some parts of the country. The Columbia area will be seeing more LID as developers use it to conform with the Columbia stormwater ordinance passed in 2007. The Hinkson Creek Watershed Restoration Project has helped to fund several LID structures (below) within the last four years, and we are eager to help fund more. For more information on these interesting projects, click the pictures directly below. Through our program, we pay 60% of the installation costs, and the business owner or landowner pays the other 40%. As you can see from our photos, LID techniques can be aesthetic features that can enhance the appearance of their surroundings, and even play an educational role.
Some of the more common examples of LID techniques are rain barrels and cisterns, porous pavement, rain gardens/wetlands, and green roofs. Other, lesser known techniques, such as engineered soil, may prove to be very useful for stormwater treatment, particularly in downtown areas. In May of 2009, we installed structural soil and a GrassPave system on the east side of the Boone County Courthouse building as part of a demonstration event for local engineers and landscapers. Buchheit Supply provided the structural soil and Missouri Petroleum provided the GrassPave material for the event. MU's Joan Smith did a PowerPoint presentation of the University's experience with structural soil, which can be found here.
At the courthouse site, a 20'x20' pit was excavated 3' down, and backfilled with structural soil. A slotted drain pipe was placed 6" from the bottom and tied into the storm drain system. After the structural soil was placed and compacted, 6" of sand and gravel was deposited to level the area for the GrassPave mat. Fertilizer and hydro-gel were then spread over the site. The mat was then filled with sharp sand, and turf will be installed on top.
The finished product at the courthouse. A Tulip Poplar was planted, sod laid, and a sign hung explaining the demonstration site and products used. Additional info on the technology:
Photo by Bill Isaacs In the picture above, the engineered soil lies below the grass. Engineered soil is basically a matrix of rock and soil that is placed in excavated basins, and often works well in conjunction with landscaped trees in urban situations. The rock within the matrix provides the load-bearing strength, while the pore spaces provide drainage and filtering for stormwater, and room for tree roots. In lab tests, researchers found that some engineered soils filtered out at least 50 percent of nitrogen and phosphorous from run off water and removed about 75 percent of heavy metals. Observations from US and Canada over 15 years show no problems regarding frost heave or freeze/thaw damage, largely due to the depths of the structural soil reservoir. Trees are finally getting recognition as the solar-powered pump/filtration systems that they are. When used in situations where they can spread their roots, such as when planted in structural soils, a tree can intercept quite a bit of water in urban situations. The difference between trees grown in areas allowing them to spread versus the typical "tree coffins" in downtown areas, is astounding. In the picture below, both rows of willow oaks were planted at the same time.
Photo by Nina Bassuk.
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