Elastomeric Check Valves Streamline Water Flow at Popular Ski Area

The Spirit Mountain Recreation Area in Duluth, Minn., provides 175 acres for skiing and snowboarding, with 22 runs, a terrain park and freestyle features. To make sure there’s enough snow during the winter months for guests to enjoy, Spirit Mountain has its own snow-making operation. That system requires about 65 million gallons of water each year. Previously, the city had used its drinking water system to make snow but sought a more sustainable water supply for snow-making.

The city decided to pump water to the recreation area from the St. Louis River. As planning for the pipeline and pumping system began, natural resource managers suggested using the same pipeline to help reduce erosion on a trout stream at the base of the ski area. From spring to late fall, the pipeline would be used to divert a portion of excess stormwater generated from the cleared hillside and other developments. Then in November and December, the pipeline would be used to pump water from the river to Spirit Mountain to make snow.

Design Challenges

Planning a reversing pipeline presented several design challenges, said Jeff Ledin, senior professional engineer at Short Elliott Hendrickson Inc. (SEH), the project’s engineer. Water used for making snow is pumped at up to 6,000 gpm. Stormwater then flows out of the pipeline at up to 20 cfs. To allow water to flow in both directions, a system using elastomeric check valves was designed.

“This pair of valves was a critical component of the project,” Ledin said. “At the end of the pipeline we have to get water to go through a T-fitting in two different directions. In one scenario, water is going out; in another scenario, water is coming in.”

At the end of the 36-foot pipeline, the planning team decided to use a Proco ProFlex™ Style 710 duckbill check valve and a Proco ProFlex™ Style 780 wafer style in-line rubber check valve. The valves work automatically, with water flowing out through the duckbill check valve and in through the wafer-style check valve. This system was placed in 20 feet of water about 800 feet from the riverbank, making it only accessible to divers and marine construction crews. Using a product that was reliable and required no maintenance was crucial, Ledin said. Getting divers to do inspection or maintenance work in the murky water would be expensive and labor-intensive.

To allow water to flow in both directions, a system using elastomeric check valves was designed.

Results

The pipeline and pumping project was completed and launched in November 2015. Ledin said he was pleased with the performance of both products, noting that the Style 710 duckbill check valve is “reliably drip tight when needed to prevent back flow.”

For uphill pumping, the ProFlex 780 allows for little headloss when water is drawn in. Ledin said the water level in the shorewell drops just 1 foot during uphill pumping. Less than half of that loss is attributed to the check valve, with the remainder to the inlet screen, fittings and pipeline. “We were very pleased when we were pulling water in for snow-making to see how little was lost through the wafer valve,” Ledin said. “Everything has been performing very well.”

Proco Products is exhibiting at WEFTEC.17, Booth 4327. For more information, visit procoproducts.com.