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Benefits of Bioretention Cells
Bioretention cells, sometimes referred to as bio cells, are shallow stormwater basins that utilize engineered soils and vegetation to capture and treat runoff. The size of the structures can vary but are typically larger than a rain garden and typically contain a sub drain to transport rain water once it has been filtered. The larger the bioretention cell, the larger the scope of vegetation that can be incorporated into the structure, including some tree species and large shrubs.
Bioretention cells utilize the engineered soil media to remove contaminates in runoff water. The soil media is generated by a mixture of sand, compost, and existing soil. The engineered soil provides favorable growing conditions for vegetation and also allows runoff to filter at a quicker rate than standard soil mixes. With a sub drain the bioretention cell can handle larger quantities of runoff at an even quicker rate. The downside of a sub drain is less water absorption into the ground but the runoff leaving the bioretention cell is cleaner than it would have been with no BMP structure in place.
Bioretention practices can range in scale of complexity depending on the site characteristics and the rate of water percolation of the site in question. Bioretention cells are recommended for sites with low percolation rates of 0.5 inches per hour while bioswales are designed for locations with high percolation rates of up to 1 inch per hour or greater.
Bioretention cells utilize the engineered soil media to remove contaminates in runoff water. The soil media is generated by a mixture of sand, compost, and existing soil. The engineered soil provides favorable growing conditions for vegetation and also allows runoff to filter at a quicker rate than standard soil mixes. With a sub drain the bioretention cell can handle larger quantities of runoff at an even quicker rate. The downside of a sub drain is less water absorption into the ground but the runoff leaving the bioretention cell is cleaner than it would have been with no BMP structure in place.
Bioretention practices can range in scale of complexity depending on the site characteristics and the rate of water percolation of the site in question. Bioretention cells are recommended for sites with low percolation rates of 0.5 inches per hour while bioswales are designed for locations with high percolation rates of up to 1 inch per hour or greater.
The design of most retention practices start with the construction of a flat surface with modified soil to capture and infiltrate as much runoff as possible. Biorention cells and enhanced rain gardens will also include a perforated sub drain to move water from the site quicker than other stormwater practices. While sub drains are a helpful feature for moving water from the site to prevent flooding, they fail to capture large runoff events as water will typically bypass infiltration and go through the outlet pipe or spill into the street to be captured by stormwater inlets. Bioswales have similar design elements but are modified with a sloping bottom and a conveyance system made of rock checks or earth berms to hold and infiltrate runoff as it makes its way downhill.
Bioretention practices can be complex and require some degree of research about the design and installation in order to execute an effective tool for capturing and cleaning storm water runoff. It is recommended to consult an engineer or professional installer before beginning. Rainscaping Iowa is an excellent place to start your search with their list of Certified Rainscapers that have experience installing many different Best Management Practices.
Bioretention practices can be complex and require some degree of research about the design and installation in order to execute an effective tool for capturing and cleaning storm water runoff. It is recommended to consult an engineer or professional installer before beginning. Rainscaping Iowa is an excellent place to start your search with their list of Certified Rainscapers that have experience installing many different Best Management Practices.