The winter of 2011-12 was a humbling snowmaking experience for many ski areas throughout the U.S. and Canada. It was, perhaps, the warmest winter in recent history, and it truly emphasized the sport’s reliance on relatively normal temperatures for snowmaking prior to the Christmas holidays. Many areas had tremendous difficulty opening just a few trails.
This experience brought to the forefront, again, the importance of modern snowmaking equipment, systems, and operational procedures to take advantage of narrow snowmaking windows.
From a broad and positive perspective, during last winter most systems produced snow in quantities that wouldn’t have been possible with the snowmaking systems from 10 or 12 years ago. Today’s snowmaking systems have achieved marked advances, and it is the task of each ski area to use this capability to its full potential. It’s unlikely that this coming winter will be a replay of last year, but every area can benefit from squeezing the maximum from its snowmaking system during the early season.
How difficult was last winter? The accompanying charts show an example of the impact on one Northeastern ski area. The charts include real world data for the month of December 2010 (Chart A) and December 2011 (Chart B). This area typically covers 135 acres of terrain and uses an average of 65 to 70 million gallons of water, and opens about 95 percent of its snowmaking terrain before Christmas.
For the sake of clarity, the charts’ vertical axis depicts cumulative operating hours/10, wet bulb temperature in degrees F, and cumulative water pumped in Mgals/day.
The differences between the two years are startling. In December 2010, the average wet bulb temperature for the month was 18.5º F. There were 491 hours of snowmaking operation, and the area pumped 55 Mgals. of water, at an average rate of 1,869 gpm. In December 2011, the average wet bulb temperature was 27.5º F, which led to 410 hours of operation and 45 Mgals. of water pumped, at an average rate of 1,827 gpm.
You read that right: the December 2011 average temperature was 9 degrees warmer than the prior December, and resulted in a 20 percent reduction in operating hours. Total water flows for the month were 18 percent lower. The average flow rates were approximately equal due to the low level of water available by the third week of December 2010.
The reduction in available hours for snowmaking highlights the need to use every available moment to the fullest. You never know when Mother Nature will force you to turn off the pumps. Here are 10 steps you can take to make sure you operate at peak efficiency.
10 POINTS TO SUCCESS1. Inspect, clean, replace and repair all snowmaking equipment. Most equipment (both air-water and electric fans) relies on tiny water nozzles and compressed air nucleation jets to break the water into small particles. The nozzles’ small orifices can become clogged with debris from a variety of sources and cause inefficient snow production. Older water nozzles and air jets can become distorted and larger due to wear—this also impairs good snowmaking production.
All uncoated ferrous snowmaking pipelines will develop a layer of corrosion on the inner diameter of the pipe during the off season. Portions of this layer will flake off early in the season and will quickly clog small snow gun water jets if unfiltered. Thoroughly flush all early season snowmaking pipelines to minimize the impact of these rust particles.
2. On compressed air systems, perform a system air pressure test prior to start up or during a lull in early season snowmaking. Fix all faulty air hydrants, and identify pipe areas that leak compressed air. For obvious pipe air leaks, repair if it is a main distribution line, and isolate with a valve if it is a trail pipeline. The above parasitic losses can dramatically lower available system air pressure. The same rationale also applies to water pipelines and overflows. During early season operations these losses can have a significant impact on snowmaking production.
3. Perform a test on your air compressors to ensure that they meet rated pressure and flow specifications. Older screw compressors will slowly lose their rated performance due to internal wear. At higher operating pressures, worn compressors’ actual air flow may be significantly below the original rating. Adjust your expectations accordingly.
4. Cool compressed air to a reasonable temperature (below 50º F), and cycle it through a moisture separator during early season operations. This will remove moisture from the compressed air, which in turn will reduce the likelihood of rime ice formation in hoses and air nucleation jets—either of which reduce high temperature performance.
5. Adopt water cooling strategies where possible. Early season water temperatures have a big impact on higher-temperature snowmaking. Process water temperatures above 50º F can have an impact of 4º F to 5º F wet bulb compared to 35º F water, depending on a number of other factors. Water cooling can be an expensive option; however the performance gains realized are worth the effort.
6. Above-ground pipelines are advantageous for early season snowmaking due to the cooling from lower ambient temperatures. Buried pipelines are at a disadvantage due to contact with warm soils. For longer-length water distribution pipelines, it may take a significant amount of time to cool the surrounding earth. This will impact early season performance even if the source water is cooled.
7. Check individual pump performance on a rotating basis to ensure full performance potential. The nameplate pump ratings for flow and pressure are not a reliable guide, particularly if the pumps have been in service for an extended time. The use of instrumentation for pump amperages, pressure, flow and temperature is a key component of effective modern snowmaking.
8. Adjust snowmaking equipment water flows frequently, both day and night, to maintain optimum production. Most air-water snowmaking towers have three or four water flow adjustments that span the snowmaking temperature range. These adjustments vary snow quality and flow—and as the temperature drops, each successive adjustment has a narrower temperature band of effective snowmaking performance. A higher-temperature flow position will produce a smaller snow crystal as the temperature drops. This smaller crystal is prone to greater drift, resulting in lost production versus a higher-flow setting.
A higher frequency of adjustment may require a change in longstanding habits of the snowmaking department. But the gains realized during the critical early season can be significant.
9. If excess system capacity is available, use it on trails that are yet uncovered. This step requires more planning operationally, and perhaps more equipment. But the more complete utilization of system resources results in more production and reduces overall system hours. This is money in the pocket!
10. The snowmaking supervisor/man-ager must have a reporting system for all hourly snowmaking system parameters to ensure that equipment and operational staffs are functioning at their full potential. These daily and real time values are an essential management tool for a modern snowmaking system.
While we will always be at the mercy of the weather, the above steps will help maximize the impact of every available early season snowmaking window and production hour. Now, if we enter a mini ice age, our advice would change some. One can only hope …