Water Harvesting

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For almost 2 decades, Facilities Management (FM) and Planning Design and Construction (PD&C) have played a major role in changing the paradigm regarding how rainwater is handled on campus.  Both were members of the Surface Water Working Group (SWWG) in the beginning.  SWWG’s charge was to reduce storm-water runoff from campus and minimize localized flooding on campus during the intense Monsoon storms we experience every year.

Prior to that time, the priority was to promote rapid runoff of storm flows to prevent accumulations that would flood at-grade or subgrade buildings and create obstacles to foot and vehicle traffic.  Reflecting that priority, new building plans and landscape designs featured slopes and or drain lines that directed runoff onto the streets to exit campus as quickly as possible. 

The problem with this paradigm was that besides exacerbating roadway flooding due to a lack of storm sewers on and around campus, it contributed to overloading local stormwater conveyance structures and wasted a precious resource.  At the same time, water was being pumped from the University wells or purchased from Tucson Water to irrigate vegetation on campus.

In 2005, a water-resources class in the Department of Soil and Water Sciences approached SWWG proposing to design and construct a water harvesting feature on campus.  After some discussions, an initial site was selected and design began.  That project was found to be impractical due to unexpectedly shallow buried electrical lines that prevented the required excavations.  However, FM suggested a new site on the south side of the Aerospace and Mechanical Engineering (AME) building. 

The landscape between the building and Speedway Blvd. featured a sloping surface covered in decomposed granite (DG).  Six downspouts emptied onto the slope, flooding it with runoff from the building’s roof. The high flow rates eroded the DG, washing it onto the sidewalk along speedway, and flooded across the sidewalk onto the street.  The water flowed past six trees planted on the landscape strip without benefitting them.

The students quickly pivoted and designed a system of swales and channels that redirects the downspout runoff into basins near the trees, dramatically decreasing runoff onto the sidewalk and street.  FM heavy equipment operators and laborers from the Grounds Shop assisted the students with the initial excavations, and installed drip irrigation lines to support establishment of new vegetation around and beneath the trees.

Through its interaction with students on this and similar projects, the Grounds Shop learned the principles of passive water harvesting and began implementing it in other places around campus. Since then, it has become the preferred method of dealing with storm-water runoff, supplementing irrigation and contributing to aquifer recharge.  At the same time, they have contributed a practical perspective to the students’ education in keeping with FM’s motto “We Graduate Students”.  

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