The city of Springfield, Illinois public works garage is using green infrastructure to capture rainwater runoff, filter pollutants, and put the water to use for other purposes.
The project included the installation of a bioswale and a rainwater harvesting system that will collect runoff, treat it, and reuse it for watering downtown plants and in the city’s jetting trucks for cleaning sewer lines. The bulk of the project is being covered by a $600,000 Illinois Green Infrastructure Grant the city received in 2014.
The rainwater harvesting cistern consists of 4 barrels of 96” diameter DuroMaxx steel reinforced polyethylene to store 94,000 gallons of stormwater runoff. DuroMaxx was the perfect material for this application as it can be constructed with watertight joints and can withstand the high depth of earth cover due to the depth of the storm sewer being routed to the storage cistern.
A CDS hydrodynamic separator was also installed to pretreat the runoff before entering the system. Pretreating harvested rainwater is essential to ensure the long-term operation of any rainwater harvesting system. Pretreating harvested water prior to storage protects downstream pumps, filters, and fixtures from damage or clogging, and it lowers cleaning and maintenance costs by keeping pollutants out of the cistern and mechanical system. It also reduces the amount of organic matter and biological oxygen demand in the cistern, decreasing the likelihood of creating anaerobic conditions and associated odors.