Abstract:

On-site stormwater management has become a major issue in early 21st century land development, with increasingly stringent regulations to prevent not only downstream flooding but also non-point source pollution and combined sewer overflows (CSO); and today’s environmentally responsive designers increasingly favor green infrastructure solutions over grey, mitigating stormwater quantity and quality in landscapes that perform multiple services, from filtration to infiltration, rather than in pipes that make the stormwater disappear. But green infrastructure strategies are particularly challenging in our rapidly developing urban areas: at the same time that the city has huge amounts of impervious surface with runoff to be managed, the dense development of expensive land makes it challenging to find room for useful green infrastructure.

Creative thinkers have transformed one of the city’s largest impervious areas—roof tops—into proven low impact development (LID) stormwater management systems through the design of green roofs. But what about stormwater management on walls, via vertical planting systems? Particularly in the urban environment, wall area far exceeds roof area; might useful stormwater management be effectively accomplished through green walls?

The authors set out to study the stormwater management viability of green walls in a simulated capture of roof runoff used to irrigate the green walls. It was also important for these green wall systems be observed by students and faculty to observe the project , so these walls were located adjacent to the entry of the academic building housing architecture and landscape architecture students. By experimenting with two green walls of different exposures (one southeast and one northwest), this study demonstrated over the course of a growing season that the southeast facing green wall retained on average slightly more than the northwest facing green wall, with both walls having similar retention volumes of conventional green roof systems.

A target was made to determine if a series of green wall systems are able to retain 95th rainfall percentile, meaning that these walls will capture 95% of 24 hour measurable rain events. Having these walls located within walking distance of classrooms and studio space allows researchers/faculty to engage students with LID stormwater practices. This oral presentation presents the methods, findings, and conclusions of the study.

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Keywords:

Green Roofs, Green Walls, COS, LID, Rainfall Percentile.