『Abstract
Storm water detention devices collect runoff from impermeable
catchments. They provide flow attenuation as well as storage capacity,
and rely on natural self-purification processes such as sedimentation,
filtration and microbial degradation. The aim was to assess the
performance of an experimental combined planted gravel filter,
storm water detention and infiltration tank system treating runoff
from a car park and its access road. Flows were modeled with the
US EPA Storm Water Management Model. An overall water balance
of the system was compiled, demonstrating that 50％ of the rainfall
volume escaped the system as evaporation, whereas, of the remaining
50％, approximately two thirds were infiltrated and one third was
discharged into the sewer system. These findings illustrated the
importance of evaporation in source control, and showed that infiltration
can be applied successfully even on man-made urban soils with
low permeability. The assessment of the system's hydrological
efficiency indicated mean lag times of 1.84 and 10.6 h for the
gravel filter and the entire system, respectively. Mean flow volume
reductions of 70％ and mean peak flow reductions of 90％ were achieved
compared to conventional drainage. The assessment of the pollutant
removal efficiency resulted in promising removal efficiencies
for biochemical oxygen demand (77％), suspended solids (83％), nitrate-nitrogen
(32％) and ortho-phosphate-phosphorus (47％). The most important
removal processes were identified as biological degradation (predominantly
within the gravel ditch), sedimentation and infiltration.
Keywords: Attenuation; Below ground storm water detention tank;
Bio-filtration trench; Infiltration; Lag period; Ortho-phosphate-phosphorus;
Road and car park runoff; US EPA Storm Water Management Model;
Water quality; Salix viminalis』
１. Introduction
1.1. Background
1.2. Aim and objectives
2. site and methodology
2.1. Site description and system operation
2.2. Water quality sampling and analysis
2.3. Model development
3. Results and discussion
3.1. Water balance
3.2. Modelling
3.3. Water treatment performance
4. Conclusions
Acknowledgements
References