Stormwater Retrofits

It is generally considered that stormwater is one of the largest sources of pollution in our country, but many people do not realize or understand what stormwater is. Stormwater is the overland flow of water and can carry anything that is on the ground (i.e. leaves, soil particles, pet waste). This water can contain a significant amount of phosphorus, nitrogen, sediment, heavy metals, bacteria and other items that negatively impact our water quality. In addition to the solids and nutrients, water volume and velocities can be a problem as well. Too much water at any given time can exacerbate the erosion of ditches and stream banks, which can create a continual source of sediment that accumulates in our lakes and streams.

Dealing with stormwater is not always an easy thing since many of the areas that need to be addressed are already developed. In order to reduce or eliminate impacts in these areas you will need to evaluate any potential open space or other areas, such as parking lots, that can be manipulated to infiltrate or store stormwater. This will allow a settling of sediments and nutrients that can be collected later.

If the soils are amenable for infiltration, then installing devices such as drywells or infiltration chambers may be an effective way to reduce stormwater. These structures are installed under the grounds surface, which makes them ideal for small acreage sites, If installing structures into the ground is not feasible, then shallow infiltration structures such as bioretention basins or rain gardens may be a preferred method of treatment. This is a good way to introduce “green infrastructure” to your community and has many additional benefits such as adding green space and wildlife habitat.

A combination of technologies can produce multiple benefits by capturing volume and sediment (subsurface stormwater chambers) and having plants uptake nutrients (rain gardens) before flowing off site. In many retrofit scenarios it is not possible to treat a large volume of water, so you plan to capture tour maximum volume and provide water quality treatment.

Throughout the Champlain watershed there are numerous projects that have been completed that showcase these technologies. Contact CWICNY or your local Soil and Water Conservation District to find out where these projects can be viewed or if you have an area of concern that you think may be amendable for retrofitting.

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