Joliet Junior College
IN-2: Innovation 2

Joliet Junior College employed a rainwater harvesting system associated with the construction of their new greenhouse facility in 2009. The system was designed to capture rainwater runoff from the roof of the facility, direct it to an underground cistern on the exterior of the building. The water is then pumped back into the irrigation system as the main source of water. The rainwater harvesting system has a dual impact on the campus, as it significantly reduces the demand of potable water required to irrigate the vegetation and reduces the storm water runoff into the storm water detention. The rainwater harvesting system is a demonstration of innovation, but was only part of the system that earned the LEED Certified level for new buildings. Further, Joliet Junior College’s Greenhouse was one of three known greenhouses in the United States to have achieved the LEED Certification at the time of its opening.

The impact to the irrigation demand on potable water obviously varies with the amount of rainfall over any particular period of time. The range of rainfall in Northern Illinois is 23.9 inches for the low and 46.9 inches for the high. The average is 37.1 inches. Over the surface of the roof it can be calculated that the rainwater harvesting collects between 128,800 gallons to 252,700 gallons on an annual basis. This reduces direct costs to JJC and overall demand on the aquafers. The second impact of the reduction to the stormwater runoff eliminates the impervious area within the watershed. This effectively eliminates 0.198 acres of tributary area from producing runoff discharging to the system. This is a very small portion of the watershed, however does provide a cumulative impact on the system.