Planning a traditional system

A traditional snow production system can vary from a small manual ski club system to a large fully automated alpine resort, World Championship- or Olympic venue system. A small manual system may consist of a generator or a couple of centrally located hydrants and with a couple of fan guns that produce snow in piles that is distributed or pushed out.  Water can simply be connected to a municipal water pipe or pumped from an adjacent creek or small lake. Depending on the water pressure, a high pressure pump must be used.

A large alpine resort or Olympic venue system often consists of a large water reservoir (from 20 000 – 250 000 m³ or more), a pump station with several high pressure pumps and air compressors, a system of pipes that can tolerate at least 30 bar pressure and with over 100 pits/hydrants along slopes, trails, hills and stadiums as well as a large amount of stationary or portable fan guns and snow lances such that the snow can be produced where the grooming and skiing takes place. Most all new large systems are automated such that the production units can start and stop automatically according to the local weather conditions, and be watched and controlled via a PC or a phone app.

The planning of the system must also include plans for staffing and operations, and ensure that staff have proper experience and are able to operate the system well.    

  • In case of smaller venues that may contemplate using some volunteer work, it can not be expected that volunteers or parents will have the same competency, flexibility or availability as permanent staff
  • How can the venue recruit and keep good operators when snowmaking is such a seasonal job?   
  • Systems that are being built must be planned with realistic staffing and operations in mind
  • Lack of knowledge or competency may cause production inefficiencies due to freezing, or experience long stops if personell do not have experience in troubleshooting problems  

In some cases the neighboring surroundings are relevant, especially if the venue is near residential areas. All snow production units produce noise, so good information to local residents and proper placements of hydrants are important elements in the planning process. Municipal noise regulations must be followed.  

Considerations

Several key questions arise when initially considering a snowmaking system:  

  • How much water is required?
    • This will depend on how much snow that is needed and how fast this snow must be produced:
      • The volume of snow is estimated by multplying the course or hill’s length and width with the snow’s depth50 cm is common 
    • Will the snow be produced in a short amount of time (needing high capacity) with many units or over longer time with fewer units?
      • This depends on how many cold days that can be expected (check climate data) 
  • Where will the water come from?
    • Is it necessary to build a reservoir, pool or large tank?
    • If the water source is a creek or a river, and the withdrawl of water affects normal water levels, it is typically required to apply for water concession from the local or federal juristiction. It is not recommended to use municipal water since this water is purified and lacks the particals that the water droplets start their crystallization from.
  • What kind of water pumps are required?
    • High pressure pumps are normally required to distribute the water out to the hydrants. However, if the water source is at a much higher location than the hydrants, the elevation drop may generate enough pressure (the pressure should be between 10 – 30 bar but higher pressure will distribute the water further)?
    • Submercible pumps will likely be required (when pumping from reservoirs, lakes or creeks)
  • Is an air compessor required?
    • This is only necessary to install if snow lances are being used
  • Should water additives be used, and are they worth the extra cost?
    • Additives (for example Snomax) can be added to the snow production water and will increase the crystallisation (more water droplets will become snow crystals). This means that more water becomes snow and that less evaporation takes place. Up to 40% increase in snow volume is possible in certain conditions.   
    • A Snomax pump is not expensive to install, but the product itself is fairly expensive (ca 1500 EURO for ca 5000 m3 water) 
  • How should the snow be distributed?
    • Should the snow production take place along the courses or hills, or in a central location (and be transported out)?
      • Fan guns and small snow lances can be moved around the courses from hydrant to hydrant, but larger snow lances are normally fixed  
      • For a Cross-Country course the hydrants should be spaced every 20 – 80 meter, depending on if fan guns or snow lances are used (see illustration below showing the same Cross-Country course optimal hydrant locations for fan guns in red, and snow lances in blue)
  • How much electricity is needed?
    • Power is needed for the pumps and compressors, and for fan guns and automatic snow lances. The total power consumption is mainly dependent on the size of the pumps and compressors, the number of production units and the wet bulb temperature (see example below for how to calculate this)
  • How will the system be operated?
    • An operating plan (including system overview, staffing etc.) and a budget for operation (with cost of electricity, fuel for machines, labour, tools etc) and maintenance (including service) must be created during the planning stage

Specification of requirements

The order of decisions when developing the system requirements are important:

  1. Decide the goals of the snow production system; is it to guarantee skiing at a certain date or early season, is it to be able to organize an event in the middle of the winter or is it to guarantee snow on a stadium/ski play area?  
  1. Research the local climate statistics (see Eklima.no if in Norway) such that the average number of good snow production days (with temperature below -5 degrees Celcius) per month is known.  For Norway, also see senorge.no (front page shown below) which provides good and unique wetbulb information for the whole country.
  1. Determine the length and width of the course or size of the stadium or hill that will be covered with snow (draw a map or plan) and calculate the required water- and snow volumes.   
  1. Determine what and where the water source is, and if a water concession is required
  1. Decide the capacity of the system; how many hours or days it should take to produce the required snow and how many production units that are needed 
  1. Determine if snow will be produced in central locations and transported out, or if the snow will be produced along the courses/hill.
  1. Decide if the water pipes will be installed below the frost line or not  
  1. Determine if the system will use fan guns (water and electricity) or snow lances (water and air pipes, but not electricity unless the snow lances are automatic), and if the system should be automated.
  1. Decide which vehicles to use for moving the fan guns and transporting the snow (if needed) 

After having gone through and considered these steps, it is time to design a master pan, estimate the water situation, gather power information and requirements as well as estimate the construction and operating expenses. This can then be used to start the tendering process.  

A hypothetical planning example

  1. The local ski club XC in Stjørdal near Trondheim airport, Norway, wishes to investigate what is needed to build a snow production system for its local stadium and lit trail system located 150 meter above sea level. The club wishes to guarantee snow on their 3 km long Cross-Country trail every year by January 1st. They can then safely committ to continue scheduling their annual 50 year old traditional event the first weekend every January. 
  1. The local climate statistic (see Eklima.no) shows how many days in November and December the temperature on average is below -5 grader Celcius near Trondheim (5 days).
  1. The required volume of snow is calculated to:  
    Stadium: 150 m (length) x 50 m (width) x 0.5 m (depth) = 375 m3
    Courses: 3000 m (length) x 6 m (width) x 0.5 m (depth) = 9000 m3
    Ekstra: 625 m3 (in case of melting etc)
    Total: 10 000 m3
    The ratio beteen snow and water is estimated to be ca. 1.5 : 1 so at least 6 660 m3 water must be available. 
  1. An existing lake and a creek exist near the stadium area. The lake is approximatelly 40 000 m3 and the creek has good water flow the whole year.   The ski club must investigate if they are allowed to withdraw water from the lake and the creek (and how much).  A pump station must in any case be planned and built. The municipal planning department will be contacted.

    By using the browser or special web sites (for example https://meteologix.com/) we can find that the humidity at Stjørdal (close to Værnes airport) on average is ca. 80 % in December. The wetbulb temperature at -5 degree C and 80% humidity is -6,8 degrees (from table in chapter “Methods”).   

    A fan gun can produce ca. 35 m3 snow per hour (using about 25 m3 water) in these conditions (see graph below the wetbulb table), ca. 400 m3 during 12 hours and ca. 2000 m3 during 5 days (assuming 12 hours production per day) in December. It will therefore be required to operate 5 fan guns to be able to produce 10 000 m3 snow during 5 days.  5 fan guns at these temperatures will use ca. 125 m3 of total water per hour (5 guns x 25 m3 each).  This is the minimum capacity for the water pumps.
  1. The 3 km course has a smooth surface but the ground is quite soft in parts, and a tractor or heavy vehicle can not drive until the ground is frozen. It is therefore best if water pipes are installed underground such that the snow is produced along the trails.   Other firm sections of the trail can be reached from the stadium via a forest service road. A preliminary drawing shows that water pipes can be installed for a total length of 1200 meters since parts of the trail goes back and forth in parallel (and snow can be made on two sections of course from the same hydrants)
  1. It is enough mountain/rock in the ground that it will be too costly to dig or use explosives to install below frost line (which is close to 1.5 meters deep). The pipes will therefore be dug shallow but deep enough to not be in the way for the grooming machine.   To avoid that the water in the pipes freezes, all pipes will need to be installed with a minimum gradient and with enough drainage pits such that the pipes empty when the pumps are shut off. In addition, the hydrants at the end of each line will always be in use or stay partially open such that the water always moves in all parts of the system.   
  1. It is known that fan guns are a bit more efficient than snow lances at marginal temperatures, so the ski club decides to put out a tender for 5 fan guns. The tender for the fan guns also includes an overall system master plan with pipes, pits, pumps etc (for total cost estimation) as well as automation since this will save operational staff and costs, and provide a more efficient snow production.
  1. The fan guns must be placed around the course late in the fall, and the ski club has access to a tractor to help pull the units (the units come on wheels).  The ski club also looks for a powerful ATV that can pull the fan guns in case of wet and soft ground condition. When enough snow has been produced, the grooming machine will move the fan guns with the front blade.

The ski club contacts one of its members that is an engineer and can assist in determining how the required power can be installed and distributed. The club draws a preliminary master plan, but expects that a snow making system fan gun provider will submit a professional system master plan.  A tendering document is then created. In parallel with this, the ski club’s chairman contacts the national ski federation, regional goverment sport office and the local municipality to get help with finding potential grants and other funding sources for the project.