It is widely acknowledged that construction site stormwater runoff is a significant source of sediments and sediment-bound pollutants to urban streams. Receiving water quality concerns associated with increased construction activities in recent years in the Greater Toronto Area (GTA) has prompted government agencies and academia to research new stormwater treatment technologies that can be used in the thousands of construction sites across the GTA. Simultaneously, Federal and Provincial governments are encouraging 60% recycling within municipalities and regions. A large quantity of compost is being produced, but not efficiently utilized. A sustainable, green technology has been developed that uses large volumes of compost material as engineered compost biofilters for stormwater runoff treatment. These compost biofilters provide a novel, effective, economical, and sustainable solution for treatment of stormwater runoff. However, test results are practically non-existent for compost biofilters from Canadian producers for stormwater treatment application. Preliminary tests indicate that compost biofilters can effectively filter out contaminants from runoff and improve the sustainability of compost operations by identifying a valuable use for the compost. The objectives of this research include: to determine through-flow properties and to develop relationships for hydraulic design of the biofilter; to determine the effectiveness of the biofilter in removing contaminants from stormwater runoff; to determine the longevity of the biofilters; and to develop a user-friendly design tool to facilitate the application of this new technology. During the spring and summer 2006 extensive laboratory and field experiments were conducted and hundreds of runoff samples were collected and analyzed. The maximum flow through rate without overtopping per unit width of the 8″ sock for the three compost materials (overs) tested was approximately 1.5 L s-1 m-1. The flow through capacities of
