  Green infrastructure has potential to alleviate the environmental impact of
rapidly growing cities. This potential has inspired laws in Toronto that
require the inclusion of rooftops with large vegetation beds, called green
roofs, into sufficiently sized construction projects. We study the problem of
reusing stormwater to irrigate a green roof in Toronto, where potable water is
the current irrigation source. The vision is that widespread reuse of
stormwater runoff for irrigation of green roofs and other purposes can reduce
sewer overflow volumes without over-building (with the added benefit of
conserving potable water). Towards this vision, our goal is to develop and
evaluate two pump controllers for transporting stormwater to the green roof of
interest in simulation. A key contribution is our development of a
site-specific non-linear model for stormwater flow using smoothing techniques
that permits linearization and a standard model predictive controller (MPC). We
compare the efficacy of the MPC, which anticipates the weather, and an on/off
controller, which is reactive rather than anticipative, for the site in
simulation. With further study, we are hopeful that this research will advance
control systems technology to improve the performance of green and stormwater
infrastructure in growing urban areas.
