How LID works
LID simply works
Low Impact Development manages water on your own site, focusing on slowing rainwater down controlling the quantity and flow of stormwater soaking it up, and using soil and plants to clean it. Slowing the water down limits erosion and pollution water runoff, filters it, and keeps water usable onsite.
When it rains in the forest, most of the water evaporates or is absorbed into the ground where it recharges groundwater or is taken up by the roots of the plants and trees. Allowing water to filter through the ground naturally, removes many of the pollutants in the water before it reaches our rivers, lakes, and marine waters.
Traditional Stormwater management (also called "gray infrastructure")
channels runoff from the site as quickly as possible. When our stormwater management process was originally created, the main concern was the potential damage to structures, so the focus was to direct runoff away from roads, buildings, and structures quickly.
Unfortunately, this type of management results in too much water, flowing along, picking up contaminants, flooding rivers, and polluting all our waterways. The gray infrastructure in many areas is aging, and it doesn't have the capacity to manage large volumes of stormwater.
Low-Impact Development (LID) (also called "green infrastructure")
is designed to mimic the natural hydrologic functions of a site.
Slowing the runoff, allows the water to filter into the soil which reduces the amount of runoff eroding land and picking up pollutants, which reduces the amount of pollutants that end up in our waterways.
The Basics of LID
Minimize site disturbance and reduce impervious surfaces where feasible (don’t pave over the whole site if you don’t need to).
Protecting and restoring native soils and vegetation (Don't remove native trees and shrubs unnecessarily. Do not disturb or compact soil unnecessarily.)
Manage stormwater close to the source (don’t let the water leave the site).
Scatter Integrated Management Practices (IMPs) throughout your site that infiltrate, store, evaporate, and/or detain runoff close to the source.
Some examples of LID technologies include:
• Engineered systems that filter storm water from parking lots and impervious surfaces, such as bioretention cells, filter strips, and tree box filters
• Engineered systems that retain (or store) storm water and slowly infiltrate water, such as sub-surface collection facilities under parking lots, bioretention cells, and infiltration trenches
• Pervious, permeable, and porous surfaces that allow drainage between impervious surfaces such as porous concrete, permeable pavers, or site furnishings made of recycled waste
• Remove curbs and gutters from streets and parking areas to allow storm water to "sheet flow" into vegetated areas.
• Native or site-appropriate vegetation.
• Low-tech vegetated areas that filter, direct, and retain storm water such as hedgerows, rain gardens, and bio-swales
• Pervious, permeable, and porous surfaces that help break up (disconnect) impervious surfaces such as porous concrete, permeable pavers, or site furnishings made of recycled waste
• Water collection systems such as subsurface collection facilities, cisterns, or rain barrels
• Shape driveways, parking areas, and Landscape areas to allow storm water to "sheet flow" into vegetated areas.
The Good News!
Not only do these techniques improve water quality, restore ground water reserves, and create a healthier yard, but many of these techniques are easily accomplished and beautiful additions to our homes.
Many of these techniques don't require any extra cost, just a different plan.