If someone said, “There’s gold in them thar snow melt pits!” you’d probably shake your head and laugh. Although the likelihood of finding gold is slim, snow melt pits are full of a resource that’s rarely considered valuable, but it is. That dirty water from the snow melt pit can be transformed and re-used for floodwater. By harvesting floodwater from the snow melt pit, you will reduce your water bill, your sewage bill — and it can even make a difference to your municipality’s potable water supply levels.
That’s exactly what they’re doing at the Scott Seaman Sports Rink in the M.D. of Foothills #31 in Alberta, Canada. By recycling their floodwater, they’re saving 300,000 gallons of potable water each year.
The Scott Seaman Sports Rink is located in an area of Alberta that is traditionally dry. The land it’s built on features two elementary schools on either side of it and a water treatment plant that provides the potable water to all three facilities. It’s a seasonal NHL-sized single pad that has ice for 10 months each year. The facility has just begun its sixth season.
The water treatment plant is supplied by two wells and the amount of potable water it can produce is limited. For the original design of the rink, being physically located next to a septic field posed a design challenge of its own. The large quantity of dirty water produced by the arena would have over-saturated the septic field if it was evacuated using the sewer system, or even if it was dumped. And dumping outdoors wasn’t an option the meticulous manager Murphy supported.
“Not only would a growing snow pile of biohazard be a tempting playground for the children attending the elementary schools next door,” Murphy says, “but I like my ice clean. I didn’t want tire marks you see at many arenas on my ice — marks that come from the dirt the tires pick up when the ice resurfacer is driven outside to dump the snow. I like a clean facility — and clean ice.”
When the arena opened, the plan was that the melted water from the snow melt pit would be hauled away. A underground retention tank was put in place to store the dirty water which had capacity sensors put in place. Once a certain level on the retention tank was met, an alarm would be triggered to let Murphy and his team know it was time to get the water pumped out and hauled away.
On paper, using conservative values to calculate user groups and floods, hauling the dirty water may have looked like a reasonable solution. In reality, with a vacuum truck costing $400/hour with a two hour minimum, hauling the melted snow away became financially unsustainable.
The arena’s grand opening was on November 16, 2013 and Murphy figures that by the end of that first week, they already knew that the arena’s hauling needs had been greatly underestimated. That’s because from 6:30 a.m. until midnight, open slots for ice time were quickly gobbled up in an area hungry for ice time. With each resurfacing, the water level in the retention tank moved higher.
“Every time we turned around, the retention tank was nearing capacity,” Murphy says.
With the vacuum truck stopping four times a week, a more sustainable solution was needed — and fast — to deal with the arena’s dirty water dilemma.
Recycling the Water from the Snow Melt Pit
Murphy wondered out loud if there could be a way to recycle the water from the snow melt pit. It was a question that had merit and the municipality called on MPE Engineering to answer it. Ryan Fitzsimmons was the engineer assigned to the study — which turned into a project.
“During the study,” Fitzsimmons says, “MPE flagged how much water they could potentially save — which was an added bonus to eliminating the trucking cost.”
After the study, the MD gave MPE direction to design a system to clean and reuse the floodwater.
“It’s fairly simplistic,” Fitzsimmons says…
(As all great ideas are…)
How It Works
After an ice clean has been made, all the ice and snow that was collected during that run are dumped into the snow melt pit. The pit is equipped with heated grates that help melt the ice and snow using reclaim heat generated from the refrigeration plant.
Once the ice and snow is melted, a skimming net is used by one of the operations team to remove the large, floating debris from the top of the melted water manually.
And then the recycling process begins.
“The water is pumped out of the snow melt pit and sent though a strainer to remove the hair, fuzz and remaining debris,” says Fitzsimmons. “Then it’s pumped through a tank that contains a four different gravel media filters, and then it’s chlorinated.”
The treated water is then stored in the underground retention tank to be pumped back into the building on demand, to be re-used, as for floodwater, as needed. There’s also a pressure filter set up with a backwash feed that’s used every day – and only the grey water is used for that.
“The treated water is considered grey water,” Fitzsimmons says, “but it’s essentially treated to the same standards as the drinking water is at the water treatment plant.” Fitzsimmons says the source well water is “pretty pristine, with manganese being the only undissolved solid they need to worry about because it gives the water a yellowish tint when treated with chlorine.
Fitzsimmons says that although MPE has been involved in many water projects, this is the only melt water recycling system they’ve been involved with to date.
Saving 300,000 Gallons of Water Annually for One Very Busy Single Pad,
Since 2014, the Scott Seaman Sports Rink is using around 200,000 gallons of potable water a year instead of the 500,000 gallons it used during its first year of operations. That’s a savings of 300,000 gallons of potable water each year.
That reduction in consumption is all because they found a way to recycle their floodwater. This floodwater harvesting solution cost just under CAN$400,000 — giving a return of investment on this project of around seven years.
The Bigger Picture
Murphy’s idea to recycle the floodwater wasn’t just possible, it’s a solution that’s working, cutting costs, reducing the arena’s environmental footprint AND safeguarding the community’s potable water supply. It’s a solution that can be transferred to all indoor ice arenas, not just in the dry Foothills of Alberta or in California and Arizona where water is scarce and expensive to buy and dispose of, but for any municipality striving to be more responsible with its potable water resources.
Want to Know More?
Here are some starting points:
M.D. of Foothills Fall 2016 Newsletter releasing results from the previous season
MPE Engineering – the consulting engineering firm who designed the floodwater recycling system
Pentair – Pump and filter manufacturer specializing in water solutions
CDM Mechanical Ltd. – the general contractor who put the system together.