Street sweeping is widely used to reduce pollutant transport into urban stormwater systems, but evidence for its water quality benefit remains inconclusive. This study quantified the pollutant load removed by regular sweeping and the load remaining on road surfaces across two catchments in the Australian Capital Territory over seven consecutive fortnightly sweeping events, using vacuum-assisted broom sweepers. Swept material was characterised for particle size, carbon, nitrogen and sulphur content, organic matter and metals, and wet vacuuming was used to compare wash-off between swept and unswept catchments.
Sweeping removed 48,076 kg (241,137 kg/km²) of dry material, comprising 36% organic matter and 1.3% of 16 metals and metalloids before entering the drainage network. Material accumulated at comparable rates in both catchments (1.5–1.8 g/m²/day) and was governed by antecedent rainfall rather than by cumulative removal from preceding sweeps, indicating that sweeping frequency mattered less than weather conditions for accumulation. When normalised to road area, the catchment yielding less material by mass yielded substantially higher loads of metals, showing that bulk mass removed may not be a good indicator of a specific elemental contribution.
Wet vacuuming of the streets showed that sweeping significantly reduced dry litter and total suspended solids in swept catchments relative to unswept catchments but did not reduce total nitrogen or total phosphorus. Phosphorus binds preferentially to the fine fraction, which sweeping captures least effectively, and an estimated 3,607-4,254 kg/km² of suspended solids and 4.0-4.6 kg/km² of phosphorus remained on road surfaces after each operation. Poor fine-particle capture has previously been attributed to conventional mechanical brooms, with vacuum-assisted units recommended as the remedy, yet the limitation persisted here despite their use.
These results confirm street sweeping as an effective source-control measure for coarse organic material and metals, while identifying fine-particle capture as its principal limitation.