Wind Chill of a Different Sort: Making Waste Water Snow
HARBOR SPRINGS, MICH.
A wispy sheet of fine snow is cascading over a field on the outskirts of town. There hasn't been much snow this year, but the powder on this piece of land is upwards of 10 feet deep.Skip to next paragraph
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I'm carefully keeping upwind of the sheet of falling flakes, but Bob Morris, manager of the Harbor Springs Area Sewage Disposal Authority, still cautions me.
"Don't let the snow get in your eyes," he says, as I move in to take a photo.
The snow, which is blasting out of two tower-mounted snowmaking guns, is made from water that's pumped straight out of the authority's waste-water holding lagoon. Harbor Springs is one of the first municipalities in the US to try this innovative technique for disposing of waste water in winter.
According to Mr. Morris, the flash freeze kills the bacteria in the water and sheds off most of the other impurities as gas and particulates. The process - developed by Delta Engineering of Ottawa - is similar to the process ski resorts use to make snow, except the water in this case isn't exactly fresh, and as yet the snow isn't being blown onto ski trails.
The waste water is pumped into snow guns under high pressure and shot up into the air. The air temperature has to be 25 degrees F. to make snow.
In the spring and summer, the snow piles melt and the particulates - mostly a phosphate fertilizer - are taken up by the grasses and other plants that grow in the field.
Three municipalities and a potato-processing plant in the Snow Belt have successfully been making wastewater snow since 1995.
In Maine, the Carrabassett Valley Sanitary District has been making snow with the waste water from Sugarloaf USA ski resort and the surrounding area. "We can say nothing but good things about the process," says plant supervisor David Keith. "Last winter we turned 25 million gallons of water into snow."
Mr. Keith said the water from the melting snow is crystal clear and probably clean enough to drink. He hasn't tried that yet, however.
Harbor Spring's snow pile, on the other hand, was a bit discolored. And a distinct sewer-like odor is released as the snow crystals shed gases from the waste water, but the perception of unpleasantness is worse than it seems, Morris says.
Health and environmental guidelines would probably allow ski resorts to use waste water to make snow for their slopes, if the resorts wanted to, Morris says. It's only the potential negative publicity that keeps them from doing so.
Many small towns use lagoon systems for treating their wastewater. After settling and natural processes remove most of the impurities, the waste water is sprayed over closed-off fields or forests with farm irrigation equipment.
In winter, though, plant workers can't irrigate because of freezing temperatures, and they have to store the waste water until spring. The snow-making process significantly increases the capacity of existing lagoon systems by eliminating the winter waste water backlog.
For towns like Harbor Springs, which are already near the maximum capacity of their waste-water treatment system, snowmaking can defer costly lagoon-expansion projects.