Low Impact Development and Green Infrastructure

Low impact development (LID), or green infrastructure, is a comprehensive land planning and engineering approach that promotes sustainabilty through the utilization of natural processes for managing stormwater and protecting watersheds. LID techniques are aesthetically pleasing, sustainable and cost-effective. LID can take many forms to provide multiple water and energy benefits.

The U.S. EPA defines green infrastructure as "systems and practices that use or mimic natural processes to infiltrate, evapotranspirate (the return of water to the atmosphere either through evaporation or by plants), or reuse stormwater or runoff on the site where it is generated." Green roofs, pervious concrete and pavers, bioretention areas, rain water harvesting and rain gardens are all forms of LID that can be applied in your community.

Not only does LID decrease the negative impacts of development on the surrounding environment and watershed, but it is a cost effective and aesthetically pleasing alternative to traditional approaches to development.

To encourage LID, the NRDC recomends that regulations should be revised to require minimizing and reducing impervious surfaces, protecting existing vegetation, maintaining predevelopment runoff volume and infiltration rates, and providing water quality improvements. From the creation of bio retention areas and grass swales, to the utilization of rainwater harvesting and green roofs, adopting LID techniques will help developers create vibrant and attractive communities that are economically vibrant, while naturally reducing the environmental degradation and carbon dioxide emissions associated with traditional development.

Ten Quick Facts on Low Impact Development

1. Across 10 case studies, holistic conservation approaches saved an average of 36% over traditional techniques.

2. Public infrastructure costs are higher when a development is built within the context of urban sprawl, as compared to smart growth patterns that conserve land.

3. Installation costs can be between $4,400 and $8,850 cheaper per acre for natural landscaping than for conventional turf grass approaches.

4. Maintenance cost savings range between $3,950 and $4,583 per acre per year over ten years for native landscaping approaches over turf grass approaches.

5. Better site design can reduce paving costs.

6. While conventional paving materials are less expensive than conservation alternatives, porous materials can help total development costs go down, sometimes as much as 30%, by reducing conveyance and detention needs.

7. Swale conveyance is cheaper than pipe systems, by some claims as much as 80%.

8. At the site level, significant cost savings can be achieved from clustering, including costs for clearing and grading, stormwater and transportation infrastucture, and utilities.

9. Green roofs are currently more expensive to install than standard roofs. Yet costs are highly variable and going down. Green roofs also have significant cost advantages when looking at life-cycle costs.

10. Several specific conservation tools can actually have multiple positive economic effects by themselves, both directly and indirectly.

From: Changing Cost Perceptions: An Analysis of Conservation Development