A Prince George's County, Maryland, study in sustainable development has yielded beneficial results for both developers and the environment including reduced construction cost, higher lot yield and cleaner water.
Under contract to the County, the Greenbelt (MD)-based civil engineering and environmental firm of Greenhorne & O'Mara, Inc. (G&O), re-examined its own development designs to make them "lay lighter on the land," said G&O Project Manager for the study Roger Kilgore, P.E. Three designs were under scrutiny-a commercial center, a townhouse community and a single-family residential development. All three had been or were in the process of being built.
The G&O team was seeking ways to improve water quality, prevent erosion and protect habitats while still keeping an eye on the developer's bottom line.
In this imaginary scenario, current codes did not apply. Both ancient and modern design techniques were considered.
Early results showed that the redesigned residential development would cost less to build if the conventional stormwater management pond were replaced with bio-retention facilities and grass swales. Six more lots also could be constructed, producing nearly a ten percent increase in lot yield.
Taking a hint from history, the team toyed with adding roof-top cisterns to catch rain. The rain water could be recycled to irrigate the lawn, thus conserving public water.
While conducting the study, the team found that the County's development regulations could be a barrier to sustainable development. For example, three parking spaces per unit are required for multi-family housing. Paved parking surfaces are a major source of NPS pollution. The team suggested that three spaces may not be necessary if the project ran near a metro station.
House setbacks could be eased to allow more steam buffers or preserve tree stands. Roadside grass swales could replace the cement curb and gutter now required.
"The environment and the public would benefit if the codes were more flexible," Kilgore said. "Developers are loathe to go through the bureaucracy of requesting a code variance unless there is a reasonable expectation of success. The key is to give the county reviewers an objective basis for evaluating the requests so developers know when a variance will likely be approved."
The County has compiled suggestions generated from studying the residential and commercial developments into a design guide for sustainable development to be distributed to developers. Estimated completion for the guide was early 1998.