Only a few years ago, decisions about snowmaking were relatively simple. You either made snow or you didn’t. Now the situation has become much more complicated because of the many different snowmaking systems that have hit the market. To get his money’s worth, the area operator must ask for quotations from different suppliers and then evaluate the bids. To do this properly, he must provide each supplier with a set of specifications for the system so everyone is quoting on the same basis.
Here are some of the points that should be included in the specifications:
The capacity and subsequent economics of any snowmaking system, conventional or airless, are usually determined by two parameters: (1) volume of snow, usually in acre-feet, and (2) coverage time, usually in hours. Some of the more important factors that will affect volume and coverage time are average temperatures, relative humidity, water temperatures, direction and intensity of wind and, related to this, natural tree cover. A design study should establish the volumetric amount of snow production required and then determine the component requirements to satisfy this production.
Piping system
The area operator should specify the type of piping system. He should determine whether the system is to be surface or underground, whether the system is to be welded or will use Victaulic-type couplings and fittings, what the construction material is to be—i.e., iron or aluminum pipe—and what the weight of the piping should be.
Where the soil permits, it is definitely advantageous to install underground piping because piping costs can frequently be reduced and the chances of freeze-up are lessened. Also, the face of the hill may be scarred with exposed piping, a point to keep in mind if the area is used in the summer. Rocky conditions, however, might rule out buried piping. In this case, the operator should try to use existing ground cover with his surface piping and manufacturers should be advised of this. The system could use underground piping for the lower mountain and surface piping for the upper portions. Again, the supplier must be advised accordingly.
Generally, underground systems should be welded and tested before burial. And the supplier should provide the operator with a precise testing procedure. In surface systems where Victaulic-type fittings are used, pressure ratings should be specified.
The materials and the wall thickness of piping are generally suggested by the supplier. The operator should not disregard this information. However, it is much easier to compare quotations if the piping in each quotation meets minimum requirements. For Victaulic and welded subterranean systems, piping should have at least a 0.125-inch wall thickness. For surface systems, minimum wall thickness (again, 0.125 inch is recommended) and pressure ratings are even more important for skier safety.
Automatic control
Every snowmaking manufacturer boasts about how completely automatic his system can be designed. Like anything else, if you can afford it, automatic control is best. On the other hand, a small system might not require such sophisticated control. The degree of control required for a system may be hard to establish at the outset, but for the purpose of comparing quotations, it should be established as completely as possible.
Other factors
There are components of a snowmaking system that cannot be precisely specified by the ski area operator. For example, it is impossible to know what air capacity will be required, primarily because each manufacturer has a different set of operating characteristics for his system. However, the operator should emphasize to each supplier that minimum air capacity must be provided to satisfy the volumetric snow requirements within the allotted coverage time. Along the same line, pumping requirements cannot be specified because of different air/water ratios for different systems. Again, the operator should emphasize that water capacity should be capable of meeting his snowmaking requirements.
To eliminate any misunderstanding on the part of the suppliers, the operator should provide weather records and topographical data for his area. Both are extremely important for the supplier to accurately size all the components of the system. If the operator does not have this data readily available, he should advise the supplier where it can be obtained. Again, this is to ensure that all suppliers are providing data based on the same climatological and topographical characteristics.
Bid evaluation
Once the bids are in, the final problem is their evaluation. For example, Manufacturer A specifies that his operating costs are $10/hour. Manufacturer B says his hourly operating cost is $15, but on evaluation, we find B produces two acre-feet during that hour, while A produces only one acre-foot. Obviously, capital expenditures being generally equal, B is the better system, with costs of $7.50/acre-foot as compared to $10/acre-foot for A.
Here is a checklist of the minimum snowmaking data that should be requested from equipment suppliers.
- Volumetric snow cover
- Operating time to achieve desired snow cover
- Air system characteristics
a. Number of compressors and unit capacity (c.f.m.), adjusted to elevation where units will be used
b. Capacity of aftercooler/separator system - Water system characteristics
a. Capacity of water pump for snow production (g.p.m.)
b. Capacity of water pump for cooling (g.p.m.)
c. List of control valves - Electrical system characteristics
a. Horsepower breakdown
I. Compressors
II. Pumps
III. Miscellaneous
b. Breaker requirements (amps) - Piping system characteristics
a. Sizes and lengths of each size
b. Material
c. Wall thickness of each size - Snowmaking equipment characteristics
a. Number of units
b. Minimum and maximum flow rates relative to minimum and maximum temperatures
c. Range of orifice sizes
d. Weight of each unit - Economic characteristics—Data should be broken down into material and labor costs for the following:
Water supply
Air system
Water system
Electrical system
Control building
Automatic control
Hill piping
Snowmaking equipment
Flexible hose
Engineering - Operating cost characteristics
a. Hourly labor costs
b. Electrical power costs
c. Fuel costs for portable components
