Low Impact Design

Stratford Place

Stratford Place now occupies a site that was previously considered infeasible to develop. The site has a high water table, is partially in the 100-year flood plain of the Skykomish and Sultan Rivers and has no outfall for stormwater release. Creatively using porous concrete and low-lying areas as open space made this property developable. Additionally, the changes made to this site also helped alleviate flooding problems for neighboring sites.

Shelby Road Cottages

This project was thought to be impossible to develop at the allowed density. Stormwater management appeared to be impossible on this, flat lot located on a signalized intersection corner, with a shallow catch basin as the only stormwater outfall. Traditional engineering would have required a substantial amount of fill to be placed on the site. With that fill, at least one dwelling unit would be lost to allow for a large and shallow, lined stormwater pond. Using a unique approach, a linear rain garden trench was implemented. This trench was able to double as the stormwater detention and water quality facility and as the required landscape buffer.

Wandering Creek

This site is located on the remnants of an old gravel quarry. Of the total site area of five-acres, four acres had been completely excavated creating large wetlands bisected by central peninsula. The peninsula is comprised of one acre of gravelly soil surrounded by four acres of wetland. Using standard engineering techniques, the site could have been developed with between one and five dwelling units. HBA Design Group designed a project with porous concrete, rain gardens and a grass-crete fire turn-around. These low-impact techniques provided adequate stormwater quality and stormwater detention without the need for typical engineered stormwater management systems.