Kirkland is among many cities in the United States beginning to establish zoning (land use) and construction (building) code regulations that facilitate what is commonly known today as “sustainable” building and development practices.
The phrase “sustainable building and development” can be characterized as balancing the need for development (i.e. housing construction) and growth (i.e. population increase) against the need to protect the natural and built environment while meeting the needs of the present generation without compromising the ability to meet the needs of future generations.
One approach to sustainable development is called Low Impact Development
(LID). LID is a set of techniques that mimic natural watershed hydrology by slowing, evaporating/transpiring, and filtering water before it reaches a stream channel. LID contrasts with current drainage techniques that collect and convey water to streams quickly – damaging stream channels and degrading water quality. This approach uses various land planning and design practices to conserve and protect natural resources and reduce infrastructure costs. LID allows land to be developed cost-effectively which helps reduce potential environmental impacts.
LID techniques may include:
- Minimize/eliminate impervious surfaces
- Retain site vegetation
- Amend soils with compost to improve water retention
- Construct bio-retention swales or cells, which are natural areas that have
specifically-chosen plans and engineered soils that slow, filter and absorb water
- Use of permeable pavement for roadways, driveways and walkways
- Installation of green roofs and/or rooftop gardens
- Installation of cisterns to hold and reuse rain water
When combined, such techniques can greatly reduce the amount of stormwater runoff from developed site and improve water quality.
To date, LID has been primarily used by developers in the City of Kirkland. Under the City’s Innovative Housing Demonstration ordinance, two residential developments -Danielson Grove (pictured above) and the Stacey Project incorporated LID practices: clustering of houses, narrow streets, rain gardens, and bio-retention swales. Several other projects have constructed narrow streets with alternative side edge treatments that direct runoff to grassy areas. A large plat project used pervious concrete sidewalks and driveways to reduce the size of required stormwater flow control facilities. The Lake Washington School District has incorporated LID into the redevelopment of Ben Franklin Elementary School.