Low Impact Development
Low Impact Development (LID) aims to mimic the natural, pre-development hydrologic pattern. The goal is to manage stormwater as close to its source as possible. In the past the driving force behind stormwater management was exclusively to move water away from buildings and streets as quickly as possible without any regard to water quality. This meant using pipes and gutters to direct water to detention ponds, retention basins and rivers.This technique has caused significant damage to water quality and the environment.
Water Quality Improvement With LID
Without any contact with soil or plants, stormwater has no chance to deposit any of the contaminants that it carries. These contaminants are brought to the river and carried to the next town downstream. To improve water quality people began implementing Low Impact Development. LID is a relatively new approach that began in Maryland in 1990. To treat stormwater near its source a variety of methods are used, but the main objective is to create small scale projects throughout the town to treat stormwater instead of costly large scale projects that do not have the capability to treat stormwater as efficiently.
LID aims to increase the time water is in contact with soil and plants before it reaches the river. Plants and soil essentially work as a filter and remove pollutants. LID also allows water to infiltrate into the ground which recharges the water table.
Examples of LID Projects
- Bioretention Areas
- Green Roofs
- Green Streets
- Green Swales
- Permeable Pavers
- Rain Gardens
Low Impact Development can be seen throughout Aspen. Find examples and pictures of these practices in Aspen.
Grass Swales & Grass Buffers
Grass swales are densely vegetated drainage ways. These swales slow down and filter stormwater. Grass swales can be seen throughout town in residential areas. Grass Buffers are similar to Grass Swales, but buffers are designed to treat sheet flow instead of concentrated or channelized flow. As water flows over grass buffers the water slows down which allows sediment to settle.
More information on grass swales and grass buffers can be found in sections 18.104.22.168 and 22.214.171.124, respectively, in the Urban Runoff Management Plan.
Impervious areas cause large amounts of runoff. This means the stormwater system has to deal with a much larger quantity of water. The higher runoff also carries more pollutants through the stormwater system and to the river. Pervious pavers allow water to infiltrate through the surface, while still providing a stable and flat paved area.
Near the John Denver Sanctuary by the Theatre Aspen tent, pervious pavers have been installed. The pavers look great while improving the quantity and quality of stormwater in Aspen.
More information on pervious pavers can be found in section 126.96.36.199 of the Urban Runoff Management Plan.
In areas that are only occasionally used for parking, grass pavers are a great alternative to pavement. Grass pavers stabilize and reinforce grassy areas. This allows bikes, cars, and trucks to pass over the area without damaging the grass. Grass pavers are constructed with either concrete or plastic and are designed with void spaces that allow grass to grow.
More information on reinforced grass pavement can be found in section 188.8.131.52 of the Urban Runoff Management Plan.
Above Ground Conveyance
Through the center of the Hyman Avenue Mall water is conveyed above ground. This stream collects stormwater and allows contact with the soil and plants along the bank instead of conveying the water underground through a pipe. On N 7th street, between Hallam Street and Main Street, water is directed from the street gutter to pervious areas.