What is it?
A subsurface infiltration basin is a below ground system that captures stormwater and infiltrates it into the ground. Subsurface infiltration basins use a system of pipes, stone, and/or underground storage chambers to store stormwater at a shallow depth underground until it fully infiltrates into the underlying soils.
When is it used?
They are used to manage stormwater under impervious surfaces, recreational areas (e.g., basketball courts, athletic fields), or other open areas. These can help you to meet stormwater requirements for development projects where available space for landscaping is limited; however, they do not provide many of the benefits that are typically associated with green infrastructure since they have no plant components.
What are some key general considerations?
- Consideration should be taken to ensure a stable path for overflows since subsurface infiltration basins are not typically designed for large storms.
- Underground systems may need special permits and the location for overflows may also need approvals. Check with your local municipality.
- Subsurface systems need to be cleaned occasionally, so it is important that these systems be designed with safe and easy maintenance access, especially for enclosed components of subsurface systems.