Abstract
Five stormwater monitoring sites were established in late 2004 within inner city Toowoomba, Australia. The monitoring sites had small catchments (50 to 450m2 area) representative of urban impervious areas (galvanized iron roof, concrete carpark and bitumen road pavement) and pervious areas (grassed and exposed bare soil). Flow-weighted samples were taken at each site to determine the event mean concentration of Non-Coarse Particles (NCP), defined as particles less than 500μm in size. Overall, runoff from 24 storms with rainfalls from 2.5mm to 48.5mm was sampled during the period December 2004 to June 2005. This paper describes the characteristics of the sampled stormwater particles including size distribution, inorganic content and mass loading generated from each surface type. On an equal area basis, the road surface produced the highest NCP load during small-to-moderate storms less than 20mm rainfall.