Description

Thomas/Wright, Inc., serving as the prime consultant, completed the conceptual level design, site selection, and design for a transfer/recycling station to replace the Vashon Island Landfill which closed in 1999. On-site improvements included access roads, water storage tanks and pumps for fire flow protection, an on-site wastewater disposal system, a new fueling station, stormwater facilities and landscaping.

A Drainage Report was prepared to address the requirements of the King County Surface Water Design Manual including discharge at the natural location; off-site analysis, runoff control; conveyance system; temporary erosion and sedimentation control; maintenance and operations; and bonding and liability.

The stormwater facilities include a two cell detention pond, a three cell wet pond for water quality, a drainage swale, outlet control structures, storm drain pipe, catch basins, and an oil-water separator. The Santa Barbara Urban Hydrograph was used to determine if the existing basin area is a closed depression.