Evaluating urban runoff pollution: sediments deposited on a road surface

The pollution caused by runoff water continues being a great problem in urban areas. Studying the behavior of sediments deposited on a road surface serves to determine the characteristics of their build-up during dry times and wash-off during rainy periods. it will also lead to establishing pollution control mechanisms associated with the sediment deposited on particular types of road surfaces. This paper presents data regarding the sediment accumulating on a road surface in the city of Torrelavega in northern Spain during a 65-day period, during which time 132 samples were collected. Two types of sediment collection samples were obtained: vacuumed dry samples (free load) and those swept up following vacuuming (fixed load). Sediment loading, particle size distribution and moisture were determined for each type of sample. The data showed that the sediment loading (gm(-2)) and vacuumed availability of the load which adhered most strongly to the surface (fixed load) increased with the number of dry days. Collected sediment particle size distribution tended to be finer with the increase in the number of dry days. <125 mu m particle sizes presented the greatest rate of build-up during dry time and those which were <500 mu m had the greatest susceptibility to being washed off during rain.