Low impact development (LID) is a method for managing stormwater that focuses on nature-based solutions for drainage and maintaining the natural environment.
Best management practices (BMPs) for LID include permeable pavement, bioretention, and tree wells.
To manage the costs of new state and federal LID requirements, we hired Aspect Consulting to identify where these BMPs are and aren’t feasible. They also created maps based on our official LID infeasibility criteria (SeaTac Municipal Code 12.10.010).
These maps show which LID BMPs aren’t feasible on public or private property. If you’re a developer, you can use these maps to check LID infeasibility on your property and to find areas where LID BMPs may be feasible.
Infiltration in soils that aren’t as permeable as the medium sands, coarse sands, or cobbles that full infiltration uses.
View limited infiltration map
Solid concrete interlocking pavers that allow stormwater runoff to pass between the pavers and infiltrate into the subgrade. Also known as permeable pavers.
View permeable pavement (concrete interlocking) map
Convey runoff from impervious surfaces to the local drainage system, while allowing for some infiltration of that runoff into surrounding soils or subgrade.
View perforated pipe
Asphalt mix that contains less fine aggregate than conventional asphalt that creates void spaces in the pavement to allow stormwater to drain through to the subgrade. Also known as porous asphalt.
View permeable pavement asphalt map
Disperses runoff over vegetated areas to help filter out pollutants and allows stormwater to soak into the ground.
View full dispersion map
Fully and reliably infiltrates runoff into the ground. Common types include drywells, gravel trenches, and ground surface depressions.
View full infiltration map
Dispersion devices that use available capacity of onsite vegetated areas to mitigate the stormwater impacts (quality and quantity) from developed surfaces.
View basic dispersion map
Concrete mix that contains less fine aggregate than conventional concrete that creates void spaces in the concrete to allow stormwater to drain through to the subgrade. Also known as porous concrete.
View permeable pavement (concrete) map
Adds compost or other organics to a soil to improve its physical properties, such as water retention, permeability, water infiltration, drainage, aeration, and structure.
View soil amendment map
Shallow landscape depressions with a designed soils mix and plants adapted to the local climate and soil moisture conditions that receive stormwater from a contributing area.
View bioretention map
You shouldn’t rely only on these maps to determine LID infeasibility. If you use these maps for a development application, Engineering Review staff will confirm the data.
For more details, see our full Disclaimer Language.