Study On Residential Area Runoff Pollution Source Control Technology Based On Healthy Water Cycle In Mountainous City

With the steady increase of urbanization quality in China, the urban sewage treatment infrastructure facilities have been improved steadily, and the controlling of point source pollution is fruitful. However,the scale of impervious surface in our cities growing significantly in the process of Chinese fast urbanization. Moreover, stormwater management pursuits "longer recurrence interval, the larger scale stormwater pipe network" and "faster drainage ". As a result,it takes a serious urban runoff pollution, on the other hand desroys the urban rainwater hydrologic cycle. Urban runoff management have become a world issue to many cities. Taking the typical mountainous city-Chongqing as an example, its runoff pollution principle is more unique and complex compared to the other plain cities. To research residential runoff pollution distribution characteristics in Chongqing, and set up a runoff pollution source controlling technical measures system based on the concept of healthy water cycle,which focuses on the construction of plot scale heathly water cycle, is critical to solve the pollution problem, repair plot scale rainwater circulation and improve the aquatic environment of residential areas in mountainous city for a long term.The Yorkville residential quarters in Chongqing, picked as the target research area. Monitoring runoff pollutions of different underlying surfaces in source areas, and building the runoff pollution source controlling technical measures system. The main results are as follows:① The runoff monitoring results of cement roofs(CRs), cement pavements(CPs) and asphalt surfaces(ASs) in six rainfall events showed that peak concentrations of COD, TSS, TN, NH3-N and TP generally appeared within 15 mins in the initial period of rainfall, and the initial runoff were contaminated heavily. Peak concentrations of COD, TN, NH3-N and TP exceeded the class-Ⅴ standard values specified in Environmental Quality Standards for Surface Water(GB3838-2002), while peak constration of TSS over the class-Ⅲ standard values specified in Integrated Wastewater Discharge Standards(GB8978-1996). Drop rate of pollutant concentrations in proper order from ASs to CPs, and to CRs during the rainfall process.② Runoff pollutions of 3 kinds of underlying surfaces in source areas are serious. The analysis of EMC showed that the monitored pollutants almost exceeded the class-Ⅳ standard values specified in Environmental Quality Standards for Surface Water(GB3838-2002) even the class-Ⅴ standard, except for NH3-N and TP of CRs. EMC of COD and TSS from ASs were significantly higher than those from CRs and CPs. The EMC of TN from ASs, CRs and CPs were similar to each other, CPs was slightly higher than ASs, CRs was minimum. EMC of NH3-N is relatively low, and concentration from high to low was ASs,CPs and CRs; concentration of ASs was slightly higher than the class-V standard values specified in Environmental Quality Standards for Surface Water(GB3838-2002), while that of CPs was closed to class-IVstandard values. The maximum EMC of TP was from ASs,and its value exceeded the class-Ⅴ standard values, and that of CPs was over class-Ⅳ standard values. As to TSS, concentration value of ASs was 1.32 times as much as the class-Ⅲ standard of Integrated Wastewater Discharge Standards(GB8978-1996),and that of CRs could reach 1.8 times that of class-Ⅱ standard value. Therefore,a runoff pollution source controlling technical measures system must be built so as to reduce runoff pollutions and to construct an ecological residential area.③ A variety of technical measures have been integrated in Yorkshire, including source control system consists of green space system, vegetative filter buffer strip, porous pavement, rain garden, cascade cyclic stormwater garden pond, and migration control system consists of grassed swales, ecological rainwater infiltration ditch, and remit control system composed of ecological riparian zone. An optimized runoff pollution source controlling technical measures system has been built.④ Operating results of runoff pollution source controlling technical measures system showed that the system could guarantee Chongguang lake water quality to maintain the pre-development state, and could meet class-IV standard values specified in Environmental Quality Standards for Surface Water(GB3838-2002). Water yield of lake can meet the ecological water demand, and water level and water area dropped less. Water quality and water quantity could meet requirements of plot scale healthy water cycle constrution.