In keeping with the old nursery rhyme, it turns out that some of the rain that goes away in Shakopee will, in fact, come again another day.
A new housing subdivision rising at the Shakopee Mdewakanton Sioux Community (SMSC) will capture rainwater that washes into the streets, treat it and then store it to be used for irrigation of residential lawns and a nearby soccer field.
That means less reliance on finite groundwater supplies.
The effort is meant to save “the high-quality groundwater that we drink — we’d like to drink [it], as opposed to spray it on marigolds,” said Stan Ellison, SMSC’s director of land and natural resources.
Reuse of rainwater has grown more common in the Twin Cities, but residential applications remain fairly rare. A similar project was completed last year in Hugo, and others are in the works.
The Shakopee subdivision features 23 homes, and the tribe expects to install a similar system at another subdivision with 50 homes.
“It actually pays for itself in about five or six years, because our drinking water is all pre-softened … so it’s pretty expensive water,” Ellison said.
The water will be treated with ultraviolet radiation, largely to kill off any E. coli bacteria that develop in the holding ponds. It will be treated to a standard that’s suitable for human contact, though not for drinking.
Ellison said that officials expect the water to meet about 85 percent of the irrigation needs for the housing developments, with the remainder supplied by regular drinking water.
Rainwater isn’t all that’s being reused at SMSC. The tribe uses its treated wastewater to irrigate a golf course and other landscaped areas. It has even explored whether treated wastewater could be used to replenish deep groundwater aquifers, a project that remains tabled for now.
Most other examples of reused stormwater involve irrigating fields and golf courses rather than lawns. Target Field in Minneapolis and CHS Field in St. Paul both are watered with stormwater, and CHS Field uses stormwater to flush toilets.
Rainwater also is being used to flush toilets at a University of Minnesota residence hall, a Shoreview city facility and Great River Energy’s headquarters in Maple Grove, according to the Minnesota Pollution Control Agency. MPCA hydrologist Scott Fox said smaller-scale applications have existed for 20 to 25 years.
“The fact that we’re actually designing systems to apply water in large areas and developments, this is different,” Fox said.
A project completed in Hugo last year uses stormwater to irrigate a neighborhood of 89 homes. “[Hugo’s] is the first project that we’re aware of that has done it this way in the state, on a single-family neighborhood,” said Hugo City Administrator Bryan Bear.
Bear said city officials recently approved a similar project for 319 homes. This summer the city plans to begin retrofitting an 1,100-unit townhouse community with irrigation from reused stormwater.