Population growth has lead to an increase in development and impervious areas in urban settings. Post-development conditions cause several problems for stormwater management such as limited space for stormwater storage systems and the conveyance of pollution picked up by runoff to near by water bodies. Green Roofs with cisterns have been shown to attenuate the peak flow of storm events and reduce the pollution load leaving a site and entering nearby water bodies. The purpose of this research is to expand the available research data on green roofs with cisterns by investigating the water quality and hydrology effects of different green roof designs including depth of media, an additional pollution control layer beneath the growth media, and different drainage layer materials. Furthermore, a comparison study is performed on the cistern water quality, direct filtrate water quality, and control roof filtrate water quality. Results show that phosphorus concentrations are lower when using a pollution control layer beneath the growing media, and that evapotransporation and filtrate factor values from the 4-inch media and the 8-inch media are approximately equal for one year. However, hydrograph results show that the 8-inch media design has a lower peak flow and longer attenuation when compared to the 4-inch media design for a single storm event. Furthermore, the drainage layer material has no significant effect on the water quality or hydrology of the green roof discharge. The data also emphasizes the importance and effectiveness of the incorporation of a cistern into a green roof system.

One of our greatest threats to surface-water quality is polluted stormwater runoff. In this research, investigated is the use of a green roof irrigated with recycled stormwater runoff to remove pollutants from stormwater runoff and reduce the volume of stormwater runoff leaving developed areas. The green roof properties of interest are the filtration and biological processes as well as the roof's ability to hold water and increase evapotranspiration, reducing the volume of stormwater runoff from the source. Because of the above mentioned reasons the experiment consists of a water quality analysis and a water budget done on several experimental chambers modeled after the green roof on the student union building at the University of Central Florida. The green roof chambers are used to study different types of growing media, different irrigation rates, and the addition of plants and how stormwater runoff quality and quantity is affected. There are also control chambers built to model the conventional roof on the student union building. The purpose of the control is to determine the effectiveness of the different media's filtration/adsorption processes and ability to hold water, in addition to identifying the benefits of adding a green roof to both water quality and the water budget. This research showed that a specifically designed green roof stormwater treatment system with a cistern is an effective way to reduce both the volume of and mass of pollutants of stormwater runoff. The year long water budget showed that this system can reduce the volume of stormwater runoff by almost 90%. The green roof model developed within this work showed similar results for the same conditions. Design curves produced by the model have also been presented for several different geographic regions in Florida. The green roof stormwater treatment system presented within this work was effective at reducing the mass of pollutants. However, the concentration of several of the examined pollutants in the effluent of the cistern was higher or equivalent to that of a control roof. Nitrate and ammonia were two that had a lower concentration than the control roof. The use of a pollution control growing media was also examined. The results of this study show that the Black & GoldTM growing media is effective at removing both ortho-phosphorus and total phosphorus. Isotherm analysis was also preformed to quantify the adsorption potential. Despite the promise of the Black & GoldTM growing media to remove phosphorus the plants did not grow as well as in the expanded clay growing media. It is suggested that the pollution control media be used as a layer under the growing media in order to get the benefits of both media.