Alice’s Garden Urban Farm, one of Milwaukee’s largest community gardens, sought a sustainable, safe water source that would reduce the reliance on municipally supplied water for irrigation. GZA designed a rainwater harvesting system and worked with the garden operator, the local non-profit Reflo, and the community to build it within the organization’s limited budget. Water quality was paramount for the crop irrigation and ultimately human consumption.


GZA’s design diverts stormwater runoff from an adjacent asphalt schoolyard into a bioswale for infiltration, which then discharges to an underground cistern with a capacity exceeding 20,000 gallons. A solar-panel-powered pump allows gardeners to access the harvested rainwater, which is routed through a filtration and disinfection system before use. A GZA engineer helped stretch the project budget by providing supportive design analysis and research via an independent study project as part of her master’s degree. She conducted a water quality risk assessment to affirm that the proposed treatment system would sufficiently mitigate human contact with potential pollutants typically found in urban stormwater runoff. A hydraulic model was also developed to help optimize the water treatment and distribution system. Other project considerations which GZA addressed included protecting existing underground irrigation lines, minimizing disruption to active garden plots, and securing off-site easements for stormwater diversion and collection. To construct the underground cistern, 150+ volunteers assembled over 625 Aquablox, a geosynthetic, interlocking tank system product.


GZA's engineers were integral to the creative problem solving, deliberate engineering design, and community engagement, which maximized the project budget, not only in the rainwater harvesting system’s construction, but in ongoing water utility bills. The combined effect of projects such as this allow the sustainable management of stormwater and help improve water quality city-wide.