INFILTRATION PRACTICE FOR CONTROL OF URBAN STORMWATER

Infiltrating stormwater locally into the ground instead of discharging to conventional pipe sewers is increasingly considered as a means of controlling urban stormwater runoff. This paper reviews the most recen t developments within this field and points out some of the major prob lems remaining. Easy-to-use methods for de signing stormwater infiltra tion structures are available but methodologies for determining the de sign parameters based on local conditions and technologies for cloggin g prevention are needed. No evidence so far points at a high risk of g roundwater contamination but the quality of surface soils will decreas e due to long-term infiltration of polluted stormwater runoff. Simplis tic modelling approaches based on conceptual process descriptions are needed for assessing the impact on soil and groundwater in local areas . The perspectives in relation to control of stormwater runoff are cle ar; the runoff peaks and volumes are decreased, and the urban hydrolog ical cycle is returned to a more natural state. In some aspects stormw ater infiltration is more effective for runoff reduction and abatement of pollution discharges than detention basins. In the future, measure s to promote urban stormwater infiltration need to be developed.