Low Impact Development and Green Infrastructure

site, goals for the project included: revitalize and reimagine this NE quadrant of London as well as clean up toxic soil conditions, widen the existing river, increasing its water-holding capacity, improve water quality, and reconnect with the surrounding city. The master plan included a strategy where many of the Olympic facilities would be repurposed for later community use and where the surrounding property would support multiple land uses and functions. Strategies for clean-up were designed to restore water flows and habitat on the River Lee, while creating an accessible greenbelt with a system of walkways and trails, recreation venues, and other passive and active recreation opportunities.

Landscape architects have increasingly incorporated storm-water management design services for clients. They employ what is referred to as green infrastructure in a variety of land and urban development projects. The application of green infrastructure in managing storm water has been adopted by public agencies under the term of low impact design (LID). The terms low impact design and green infrastructure generally refer to design systems and practices that mimic natural processes to infiltrate or reuse storm water on the site where it is generated rather than dispose of it off-site through an underground system of pipes. On-site collected storm water is allowed to percolate to recharge water aquifers and for onsite irrigation and other purposes. Green infrastructure can be used at a wide range of landscape scales and project types. The aim in employing low impact development is to replace or minimize having to construct expensive underground storm-water systems that collect water to be piped to a central wastewater treatment plant or directing the pollution-borne waters to a stream or other natural hydrologic feature. The concept is to treat storm water as a resource to be used on-site rather than as a waste product to be removed.

An example of low impact, green infrastructure is shown in Figure 5.34. The firm of Ahbé Landscape Architects of Los Angeles, CA, redesigned one side of an existing city street in Burbank, CA, with a bioretention swale. The original street design followed a traditional approach to mana ging storm water, using curbs and catch basins to collect surface water, directing the captured water to an underground storm-water infrastructure. With the new design, surface waters are collected in a depressed planting strip that parallels the street. Surface waters are detained in the planted, linear basins and allowed to percolate to the aquifer below. The species of plants not only enhance the aesthetics of the street but take up some of the pollutants washed from the street, thus improving water quality.

Figure 5.34 Bio-retention swale, Burbank, CA, by Ahbé Landscape Architects.