Stimulated by the recent USEPA＇s green stormwater infrastructure （GSI） guidance and policies, GS1 systems have been widely implemented in the municipal area to control the combined sewer overflows （CSOs）, also kn...Stimulated by the recent USEPA＇s green stormwater infrastructure （GSI） guidance and policies, GS1 systems have been widely implemented in the municipal area to control the combined sewer overflows （CSOs）, also known as low impact development （LID） approaches. To quantitatively evaluate the performance of GSI systems on CSO and urban flooding control, USEPA-Stormwater Management Model （SWMM） model was adopted in this study to simulate the behaviors of GSI systems in a well- developed urban drainage area, PSW45, under different circumstances. The impact of different percentages of stormwater runoff transported from impervious surfaces to the GSI systems on CSO and urban flooding control has also been investigated. Results show that with current buildup, GSI systems in PSW45 have the best performance for low intensity and short duration events on both volume and peak flow reductions, and have the worst pertbrmance tor high intensity and long durataon events. Since the low intensity and short duration events are dominant from a long-term perspective, utilizing GSI systems is considered as an effective measure of CSO control to meet the long-term controlstrategy for PSW45 watershed. However, GSI systems are not suitable for the flooding control purpose in PSW45 due to the high occurrence possibility of urban flooding during or after high intensity events where GSI systems have relatively poor performance no matter for a short or long duration event,展开更多
Green infrastructures such as rain gardens can benetit onsite reduction ot stormwater runott, leading to reduced combined sewer overflows. A pilot project was conducted to evaluate the impact of rain gardens on the wa...Green infrastructures such as rain gardens can benetit onsite reduction ot stormwater runott, leading to reduced combined sewer overflows. A pilot project was conducted to evaluate the impact of rain gardens on the water quality and volume reduction of storm runoff from urban streets in a combined sewer area. The study took place in a six-block area on South Grand Boulevard in St. Louis, Missouri. The impact was assessed through a comparison between the pre-construction （2011/2012） and the post-construction （2014） phases. Shortly after the rain gardens were installed, the levels of total suspended solids, chloride, total nitrogen, total phosphorous, zinc, and copper increased. The level of mercury was lower than the detection level in both phases. E. coli was the only parameter that showed statistically significant decrease following the installation of rain gardens. The likely reason for initial increase in monitored water quality parameters is that the post-construction sampling began after the rain gardens were constructed but before planting, resulted from soil erosion and wash-out from the mulch. However, the levels of most of water quality parameters decreased in the following time period during the post-construction phase. The study found 76% volume reduction of stormwater runoff following the installation of rain gardens at one of studied sites. Statistical analysis is essential on collected data because of the encountered high variability of measured flows resulted from low flow conditions in studied sewers.展开更多
文摘Stimulated by the recent USEPA＇s green stormwater infrastructure （GSI） guidance and policies, GS1 systems have been widely implemented in the municipal area to control the combined sewer overflows （CSOs）, also known as low impact development （LID） approaches. To quantitatively evaluate the performance of GSI systems on CSO and urban flooding control, USEPA-Stormwater Management Model （SWMM） model was adopted in this study to simulate the behaviors of GSI systems in a well- developed urban drainage area, PSW45, under different circumstances. The impact of different percentages of stormwater runoff transported from impervious surfaces to the GSI systems on CSO and urban flooding control has also been investigated. Results show that with current buildup, GSI systems in PSW45 have the best performance for low intensity and short duration events on both volume and peak flow reductions, and have the worst pertbrmance tor high intensity and long durataon events. Since the low intensity and short duration events are dominant from a long-term perspective, utilizing GSI systems is considered as an effective measure of CSO control to meet the long-term controlstrategy for PSW45 watershed. However, GSI systems are not suitable for the flooding control purpose in PSW45 due to the high occurrence possibility of urban flooding during or after high intensity events where GSI systems have relatively poor performance no matter for a short or long duration event,
文摘Green infrastructures such as rain gardens can benetit onsite reduction ot stormwater runott, leading to reduced combined sewer overflows. A pilot project was conducted to evaluate the impact of rain gardens on the water quality and volume reduction of storm runoff from urban streets in a combined sewer area. The study took place in a six-block area on South Grand Boulevard in St. Louis, Missouri. The impact was assessed through a comparison between the pre-construction （2011/2012） and the post-construction （2014） phases. Shortly after the rain gardens were installed, the levels of total suspended solids, chloride, total nitrogen, total phosphorous, zinc, and copper increased. The level of mercury was lower than the detection level in both phases. E. coli was the only parameter that showed statistically significant decrease following the installation of rain gardens. The likely reason for initial increase in monitored water quality parameters is that the post-construction sampling began after the rain gardens were constructed but before planting, resulted from soil erosion and wash-out from the mulch. However, the levels of most of water quality parameters decreased in the following time period during the post-construction phase. The study found 76% volume reduction of stormwater runoff following the installation of rain gardens at one of studied sites. Statistical analysis is essential on collected data because of the encountered high variability of measured flows resulted from low flow conditions in studied sewers.
