Snow production

Introduction

Snow production is relevant for all types of venues that depend on snow. This includes venues for alpine skiing, snow parks, Cross-Country, Biathlon, Ski jumping and community- and “base” venues. Insufficient natural snow is a problem for most ski venues and resorts. Snow production will contribute to an earlier season opening and longer duration. A good base layer and replenishment of artificial snow will contribute to securing good and stable conditions throughout the winter. Snow can additionally be produced for special events.

Community- and base (skill) venues are venues located near population centers or in existing arenas, and are first and foremost prepared for youth and children (also called “ski play” areas). Snow elements in these venues are meant to create spontaneous interaction between youth/children in a skiing environment that challenges basic balance and agility.


_{Photo: Norwegian Ski Federation}

Snow parks are also relatively new venues that require large amount of snow since most of the elements are built entirely by snow. Skicross is yet another example of a discipline that created a need for more snow in venues.

Skicross is established in both alpine and Cross-Country:
– courses are created with technical elements that suit different ages and ability levels
– includes waves, jumps, corners with or without banking etc.
– can be created as its own course in the terrain 
– can use existing slopes and incorporate terrain elements from ski play- or “fundamental skill” venues, and in addition amplify existing terrain with waves, jumps and banked corners.

1

Methods 

Today there are three main methods of providing snow for a ski area without being dependent on natural snowfall: 

• Traditional snow production in below freezing temperatures (a)
• Temperature independent snow production in above freezing temperatures (b)
• Storage of snow (over the summer) of natural- og artificial snow (c)

In addition to these three methods, it is also possible to cool down a production area (tent, garage, snow tunnel etc) by using liquid nitrogen or electricity such that traditional snowmaking can take place.

Traditional snow production systems 

Description and equipment 

Traditional snow production systems have been around for many years, and work only in specific weather conditions; production can only take place if the wetbulb temperature is ca -2 C or colderWetbulb temperature is a combination of air temperature and humidity

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The ratio between injected water and produced snow varies from 1.7 – 2.5 parts snow per 1 part water (1 m³ injected water will produce 1.7 – 2.5 m³ snow), depending on wind, temperature, the quality of the snow (dry or more humid) and other factors. 

• It has been shown that between 15 – 40 % of the water that is injected in snow production systems either evaporates, blows off the course/hill or disappears in other ways.

The systems can be both stationary or mobile. Mobile systems may be suited for community venues, small ski jumps or small Cross-Country/Biathlon venues, but are very labour intensive.

Mobile systems are powered by a large generator (usually placed on a trailer or tractor) and have portable pumps and snow fans. In this example the generator on a trailer is moved around in the terrain together with the snow fan. The only external connection needed is water with relatively low pressure (2 – 7 bar). 1 bar is 14.5 PSI. This can come from nearby creeks or municipal water lines.

New snow production systems are normally designed and sold as half-automatic or automatic systems, but we still use the terms manual, half-automatic and automatic systems. 

Manual systems require that the operator must manually start/stop, as well as adjust the pumps and fan guns. The number of nozzles and/or amount of water added to each fan gun must be adjusted manually to produce the best possible snow quality. To achieve a good result, the snow maker must be very skilled. It is labour intensive to operate manual systems, and supervison is needed every 1 – 2 hours both night and day. Since the automation is in the fan gun itself, it is possible to install an automatic fan gun together with other manual ffan guns in a manual system. Manual system are recommended mostly for smaller ski venues, but can also be recommended for sites with cold, stable temperatures and with relatively limited snowmaking needs.

For half-automatic systems some of the adjustments are simplified such that a fast start- and stop procedure can be done for multiple fan guns simultaneously. This is done by pre-installing air and water intakes on the fan guns. The fan guns will start up when the main pump station adds air and water to the pipe system. The disadvantage with this system is that it provides for poor quality control. For a sfan gun it means, for example, that the startup temperature must be adjusted manually while the fan gun itself adjusts the amount of injected water relative to this set temperature. The advantage with a half-automatic system is that it is less expensive than an automatic system and have minimum maintenance. These systems are suitable for larger venues and at sites with little wind and cold conditions.

All larger alpine venues have automatic systems, and these systems are more and more common also in smaller alpine venues and in larger Cross-Country/Biathlon venues. Pumps, compressors og fan guns start and stop based on pre-set values and parameters such as air temprature, humidity, water temperature and the time of day. These systems produce up to 20 – 40 % more snow compared to equivalent manual systems. The fan guns need limited supervision during operation and saves labour. The automation will work with all types of fan guns and snow lances, and the snowmakers can monitor a large number of units from either a PC, web cam or smart phone. The disadvantage with such a system is the high initial cost and that maintenance is complicated.

A snow production system consists of the following elements: 

• A water source (reservoar, lake, river/creek or municipal water lines)
• Possibly a cooling tower (if the water is warmer than 3 – 4 degrees Celcius during the snow production period).
  • A cooling tower should be considered if it is known that the water temperature is too high, and is especially useful for snow production in marginal temperatures (will improve the efficiency of the snow fans)
  • Along it way down the tower, the water is circulated through pipes while a strong fan blows cold air over it.  The water will decrease in temperature both due to the contact with the colder air and the cold steel, which cause evaporation (release of heat) from the water droplets.  The colder water is collected at the bottom of the tank and further use in the snowmaking process.
  • If a reservoir is built as part of the snowmaking system, a bubble system can instead or in addition be installed to move water and increase the cooling effect by the air on the surface.  The speed of the pump in the bubble-system regulates the cooling effect (be careful not to cause ice build-up).
  • Cooling towers come in many sizes, can be delivered as a unit or built in place by available components. It is a relatively simple construction
  • 

• If desirable, water additives that are mixed into the snowmaking water through a separate pump, for eksempel Snomax (snomax.com) or Drift (aquatrols.com/drift ), and that in most cases will increase the amount of snow produced
• A system of pipes and hydrants that distributes water and air to the fan guns and snow lances.
  • Water pipes used for snow making are constructed in galvanized steel or cast iron (steel is also used for air pipes), and must withstand 30 – 80 bar from the high pressure water pumps, depending on the elevation the water needs to be lifted.
    • The pipes should optinmally be buried below freezing level in the ground such that they can be filled with water that is immediatelly available for snowmaking  
    • The pipes can alternatively be buried shallow (or even laid on top of the ground) but must then be drained every time the system is stopped (to avoid freezing). Additionally, each endpoint must be open such that water is always flowing in the pipes.
    • Both methods have pros and cons:
      • Pipes on top of the ground:
        Pros: Lower cost, easy to inspect, can be cooled by cold air, easy to service
        Cons: Looks ugly, often requires extra safety for skiers, needs special anchoring due to the possible jolting when the high pressure water pump starts up
      • Buried pipes:
        Pros: Not visible, less prone to freezing, not in the way of course layouts or grooming
        Cons: Higher investment costs, eventual leaks are difficult to identify, no cooling effect by cold air
  • Hydrants are installed above ground or in pits every 20 – 80 meters around the course or in a few central locations. The fan guns or snow lances are connected to the hydrant with a cam lock using a snowmaking hose (usually 20 meter long). Larger fan guns or snow lances are connected directly to the hydrant without using a hose (or by using a stiff, self-draining hose). Multiple hoses can be connected to each other, with an equally long power cable. 
• Pumps
  • A separate “feed pump” brings the water from the water source to the high pressure pump that pumps the water out into the pipe system. Depending on the water source, an intermediate cleaning reservoir or tank may be required. It is important to install filters such that dirt- or sand particles do not block the on-boards filters on the fan guns or wear the pumps uneccessary.  
  • A pump house with one or more high pressure pumps must be built solidly with a proper concrete foundation/floor and be insulated to withstand the weight, wet weather, cold temperatures etc.
    •  For snowmaking systems regular sentrifugal pumps are used. These are delivered in different sizes depending on the required capacity. The pumps should be dimentioned concervatively (for possible future expansion).
  • If the water source is located at elevations high above where it is used, the gravity will provide parts of the required water pressure, such that the size and power needs for the pumps can be reduced (or even eliminated in some cases). It can be estimated that a 300 ft difference in elevation will provide almost 10 bar of water pressure when connected by a pipe.
  • Usually the snow production system provider is helpful in calculating the size and number of pumps required for the amount of water and required water pressure.
    • The range of the water pressure for snow lances is 15 – 50 bar
    • The range of the water pressure for fan guns is 8 – 40 bar, depending on the model
    • The required pressure will depend on the elevation change of the pipes
  • Mobile pumps can be delivered in small containers. These are handy when several sites share production units, or when the snowmaking needs are irregular or infrequent.
    
    
• Compressor station
  • An air compressor system for snow lances is based on supply of high pressure air from a centrally located compressor. The capacity of the compressor determines the capacity of the snowmaking system. Compressors are noisy, and it is important that sound-insulation is used in the compressor house.
    • This type of snow production has two pipe systems, one for air and one for water. Other important parts are a condensor and a cooling system for the air. The air must have a pressure of ca. 7 – 8 bar, and the temperature should be 4 – 8 degrees C.
  • There are mainly two types of air compressors used in snow production systems.
    • A piston compressor is often purchased used. The compressor can not be loaded more than 80%.
      • a worn compressor may leak oil
    • A rotary screw compressor is a more modern compressor that can be loaded 100% when operating continuosly. The total capacity can therfore be reduced by 20% compared to a piston compressor
• Production units
  • Fan gun for systems based on water and electricity, and a single system of pipes
    • Uses water only (has on-board compressor) 
    • Has a large capacity (up to 90 m³ of snow per hour for the largest models) 
    • Can easily be adjusted and angled according to the wind direction 
    • Can “throw” snow up to 80 meters (in piles or “whales” along the hill or course) 
    • Needs electricity 
    • Is relatively expensive (ca. 30 000 EUR per fan gun) 
    • Energy consumption per m³ snow is between 1 – 2 kWh in cold temperatures (colder thaan -8 C) but can be as high as 8 kWh at marginal temperatures
    • Is typically lifted and moved from hydrant to hydrant using the grooming machine’s front blade (is usually pulled by a tractor, truck or ATV for the initial pre-season setup). Is also installed permanently on towers for alpine and ski jumping venues
      
      
  • Snow lance for systems based on supply of compressed air from a central compressor and water from a central pump
    • Uses both water and air (which is mixed externally, or internally inside the lance’s head by a nucleator nozzle)  
    • Comes in many sizes, both stationary and portable types
    • Needs two sets of pipes and hydrants for distributing the air and the water
    • Has less capacity than fan guns (see graph below)
    • Can, depending on the model, be adjusted in 1 – 4 (or more) positions according to the wind direction
    • Will normally produce snow in a cone-shaped pile underneath the snow lance, but can throw 10 – 30 meters  
    • Does not need power unless it is part of an automated system 
    • Is reasonably priced (~3 000-5000 EUR)  
    • The energy consumption per m³ snow is between 0.5 – 1 kWh in cold temperatures (below -6 C) but can be as high as 6 kWh in marginal temperatures
    • Is normally installed permanently for alpine and ski jump venues, but portable models are often used for Cross-Country

• A source of electricity with power for pumps, air compressors, automation and production units
  • The power requirement must be estimated and investigated before planning and establishing a snow production system, including the possibilities and conditions for bringing in and installing transformers. The providers of snow making system production units are usually helpful in determining the required power dimensions.  
  • Manual or non-automated snow lances do not need power, but electricity for fan guns must be installed in cabinets or in pits together with the water hydrants
    • Most of the larger fan guns need 400V 63 A, while smaller models need 400 V 32 A.
  • Power cables for the fan guns must be purchased (especially extra long ones when using multiple hose lengths)

Production capacity

• The snow production capacity for a fan gun or a snow lance depends on the wetbulb temperaturecombination of air temprature and humidity – see table below

• The average wetbulb temperature almost anywhere in the World can be found at the web site Climatemps.com
• A fan gun or snow lance can produce much more snow at low temperatures and in dry air.  The capacity for a standard fan gun and snow lance relative to the wetbulb temperature is shown below (from Bernhard Vagle, master thesis). The graph shows that the snow production capacity doubles from -7 to -14 degrees C. 

By using information from the mentioned web site, the table and graph above (local wetbulb temperature and capacity for fan gun and snow lance), it is possible to estimate the capacity for snow production anywhere (see example showing how to do this later in this section). 

It is however important to be aware of that local crosswinds and evaporation may reduce the capacity or cause loss. For a narrow Cross-Country course this loss can be as high as 40 – 60%, for a ski jump hill 20 – 40%, and for an alpine slope 10 – 20%.  Evaporation of up to 10% can also happen during very cold temperatures or when very small nozzles are being used. 

Temperature independent snow production

Description

The most cost- and energy efficient snow production technology is still traditional production in cold tempeatures (artificial or man-made snow production will use from 0.5 – 6 kWh energy per cubic meter snow).  It is also quite normal to use shaved ice from hockey- or ice skating arenas to supplement artificial snow during warm temperatures, especially for skiing events in or near cities. 

Because of the climate changes, with fewer cold days and less natural snow in lower elevations, there is an increased interest in technologies that can produce snow or ice in warm temperatures.   This technology is not new; ice has been used for many decades in the fishing- and mining industry as a cooling element. It is today at least 3 – 4 commercial producers of ice/ice-slurry for ski venues, and the technology can be divided into three main systems and products:

1. “Binary snow” using vacuum technology  
2. Ice slurry technology 
3. Flake ice technology 

All the technologies can produce snow or ice in temperatures up to over over +20 degrees Celcius.

Technologies

Vacuum technology 

The vacuum technology produces binary snow by injecting ca. 4 degrees C water into a vacuum chamber. The vacuum effect initiates an evaporation (vacuum evaporation), while the temperature in the rest of the water decreases, such that ice is generated at zero degrees Celcius. 20 % of this is fine ice crystals (binary snow) that is separated after it is pumped into a snow concentrator. The snow is then pushed out while the water is pumped back into the vacuum chamber such that the process can be repeated. Since water is used as the cooling element in the system, it depends on a cooling tower unless water is available from a cold mountain river or mountain lake.  

The vacuum machine can utilize the generated heat, but this is conditional on installing a heat pump that can lift the tempeature to a higher level, as well as run the external cooling tower separately from the snow production.  

Systems using the vacuum technology are installed in Zermatt, Switzerland, Pitzdal, Austria (alpine) and Lago di Tesero in Val Di Fiemme (Cross-Country).

Ice slurry technology 

There are several companies, both in Scandinavia and North-America that can deliver snow that has been separated from ice slurry, and that are using standard cooling technology. 

The technology, in simple terms, consists of a cooling system and an ice-slurry generator (liquid mixture of salt and water). After cooling (takes place by evaporation of a cooling medium) the snow is separated from the rest of the liquid in a snow/ice separator.  This system uses a pump that circulates the liquid. The ice/snow attach to the suraface of plates and is scrapes off by knives.  

A variation of the same technology consists of a rotating system and therefore eliminates the need for pumps, thus reducing the energy consumption by 30%.     

Torsby Ski tunnel, Anglagården ski hall in Sweden, and Kivikko ski hall in Finland uses ice-slurry systems. The system was also used during the 2014 Winter Olympic Games in Sochi on the Nordic Combined courses.

Flake ice technology

Flake ice technology is a standard technology that is used in many known cooling systems, such as production of ice and air conditioning.  Water is cooled by compressed gas or a liquid, ice is created on a surface and is then cut off in small pieces and collected. Many companies are delivering flake-ice systems.  

Geilo, Sjusjøen, Skiforeningen in Oslo, Norway, Idrefjell in Sweden, Lake Placid and North Star in the USA and several veneus in Germany uses flake ice systems.

New technologies

New technologies for temperature independent systems are being developed, using heat pumps, dry ice etc. With optimal water temperatures (as cold as +2 degrees Celcius) also these systems may reduce their energy demand to below 10 kWh per m³ snow.

Comparison of technologies 

Some of the temperature independent systems are using ammonia or freon as cooling elements, while others are using water or nitrogen. Most of them use about 1 – 2 liters/second of water (large vacuum technology machines use up to 6 – 7 liters/second), and the water pressure is between 2 – 5 bar. The table below shows approximate capacity, energy usage, size of the production units and an estimated cost of the system.

Technology	Ice or snow	Ca. capacity  (m3 snow per 24 hrs)	Ca, energy usage (kWh per m3)*	Size in meter (l x w x h)	Cost (EURO)
Vacuum	Snow	860	7 – 11	30 x 30 x 15	Up to ca. 3.5 mill
Ice slush	Snow	267	22 – 26	20 x 10 x 7	Ca. 1.5 mill
Ice slush	Snow	250	18 – 20	20 x 10 x 10	Ca. 0.9 mill
Flake ice	Ice	220	29 – 34	30 x 10 x 10	Ca. 0.7 mill
Flake ice	Ice	450	29 – 34	40 x 10 x 10	Ca. 1.4 mill

In addition to the costs listed in the table above, additional costs will likely occure, although those costs are quite similar for all the systems.

• installing electricity and water
• preparing a flat and paved surface
• buildings
• general operations
• maintenance (more for those with many mechanical components)
• distribution of the produced snow (some systems can blow snow up to 200 meters through pipes)

The table shows that vacuum technology is the most effective, both in terms of capacity and energi usage (ca 10 kWh per m³ snow).  The product has higher quality (better snow to ski on) than for example flake ice. But, the technology is an expensive investment and may need a large space and shelter/building.

Ice slurry systems are quite energy demanding (ca 18 – 26 kWh/m³ snow), but the quality of the “snow” is similar to vacuum technology and is better than for flake ice systems. The system is often deliverd as a “plug and play” system (add water and electricity only) and is portable. The technology is still developing, but is used in many locations. 

Flake ice technology has the highest energy consumption per m³ snow/ice (over 30 kWh/m³).  Several companies deliver this technology. The injected water must be clean and from municipal water pipes. The produced ice must be crushedby grooming machines and mixed with natural snow or transformed by precipitation before providing an optimal skiing surface (venues are also exploring different methods). The system is relatively easy to operate, and comes in modular “plug and play” modules (capacity can be doubled by adding two modules together).

Investing in a temperature independent system 

Several questions should be consided before purchasing a temperature independent snow production system.

1. It must first be clarified if the main goal is to be able to promise a fixed, annual opening date for skiing (for example November 15). If this is not important,  the focus should rather be on improving an existing- or installing a traditional snow production system, and optimizing this such that large amount of snow can be produced in a short amount of time during cold temperatures. However, if it is desirable to guarantee early skiing independent of the weather, further clarification and decisions are needed.

2. The next question should be if it is possible or practical to store snow over the summer? It is in most cases cheaper to produce artifical snow (during the winter) and store this (with 15 – 35 % loss) than to produce snow or ice with temperature independent systems in the late summer or early fall. It is however difficult to store snow at low elevations (near sea level) in warm summer temperatures, or might even be impossible due to municipal restrictions inside city limits.

3. If it is not possible to store snow, it should next be clarified if a temperature independent system is locally accepted in today’s political climate discussion. All temperature independent snow- or ice production systems will use much more energy than a traditional cold temperature system (2 – 5 kWh versus 10 – 35 kWh per m³ snow).  

4. It is further important to decide how much snow to produce since this will determine the capacity of the system. For example, a 2 km long Cross-Country course needs minimum ca. 4000 m³ snow (for a ca. 6 meter wide course with ca. 30 cm depth).  A temperature independent system will loose about 10 % snow due to melting, so 4400 m³ should be produced. It is also important that the snow density is suitable, for Cross-Country skiing this should be at 400 – 450 kg/m³. A production system (for example a double module flake ice system) with capacity of 200 m³/24 hrs will need 23 days to produce enough snow (and will use about 100 000 kWh for an approximate electricity cost of NOK 115 00011 000 EURO (depending on the system and price of electricity). 

Decision matrix for considering temperature independent systems:

Using liquid Nitrogen or CO2 

Liguid nitrogen or CO2 is already used for many cooling purposes. It can also be used to cool down a tent such that it becomes suitable for a traditional snow production system – by spraying the liquid nitrogen/CO2 into the air. This may lower the temperature towards – 40 degrees Celcius inside the tent. Water droplets from a regular fan gun will rapidly freeze, and may produce 20 – 30 m³ snow per hour.  

This method was used for the August 2016 X-Games Big Air event at the Tøyen Park, Oslo, Norway (https://polareurope.com/). 

2

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?  

2. 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.

3. 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.   

4. Determine what and where the water source is, and if a water concession is required

5. 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 

6. Determine if snow will be produced in central locations and transported out, or if the snow will be produced along the courses/hill.

7. Decide if the water pipes will be installed below the frost line or not  

8. 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.

9. 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. 

2. 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).

3. 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. 

4. 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.

5. 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)

6. 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.   

7. 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.

8. 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.

3

Tendering and construction

Tendering process

When the decision, planning and financing of a new snow production system is in place, the actual tendering and construction process starts. The first task is to obtain offers from suppliers of the snowmaking system components as well as from construction companies that can do the required earth work and assembly. To do this properly requires tendering documents that clearly describe the venue, specify the requirements and describe all components of the system.

For larger systems it is challenging for a venue owner (or the party initiating the process) to know all the details required for a good and fair tendering process, It is therfore quite common to organize a dialogue conference and one-to-one meetings with the interested snowmaking system suppliers. In this way the suppliers can be part of designing a good system, and help identify important elements for the tendering documents. It is important to take good notes and protocols from the dialogue conference, and make sure all interested suppliers and parties receive the same information.  

The tendering documents should describe the system requirements, and in a clear way what the potential providers are expected to deliver in their bid. Clarity is important such that the different bids and offers can be easily compared.

• An example of a system requirement can be (for an alpine venue):
  • A topographical map showing the planned layout
  • A general description of the area:
    • Total slope/courses: 1000 m long, 30 m wide
    • Snow: 40 cm depth, density 400 kg/m³
    • Estimated temperature at startup: Wet-bulb from -8 to -4 °C
    • Production time: 150 hours
• This will then enable the supplier to suggest a masterplan and give a price for the components

A snow production system consists of several parts and components, and the tender can therefore be divided into several parts that the bidders answer and provide a price for. Since most suppliers of snowmaking system components prefer to work with a separate construction company (who performs the required ground work), two tenders may be required.

• Provide a masterplan that includes description and details for water intake, pumphouse and pumps, types and sizes of pipe, number of hydrants, number and types of suggested production units etc.
• Cost for all parts shown in the masterplan, as well as automation software, education of staff, commissioning, service osv. 
• Cost of providing and installing pumps
• Cost of providing and installing air compressors 
• Cost of delivering pipes and installing/connecting them 
• Cost of delivering pits, valves and hydrants and installing them
• Cost of the production units (fan guns or snow lances)
• Cost of building the pump house*
• Cost of installing power and data cables, and affiliated distribution boxes etc. *
• Cost of digging ditches, eventual blasting, filling and compacting ditches after pipes, pits and cables are installed*
  
  * the marked lines are often a separate “construction tender”

It is also important to decide how to coordinate the construction work; will the ski club or venue owner be responsible for this, or will the project coordination be done by a general contractor that coordinates the work done by sub-contractors? This must the clarified in the tender documents and also be included in the cost sheet that the bidders provide (if they are expected to coordinate the project).  

The tender document could include the following sections:

• Area layout, system requirements and functional description  
• Criteria for comparing the bids
• Criteria for awarding the winning bid 
• Cost sheet with all components listed

It is also important that the criteria used for the internal evaluation are discussed and written down before the bids are received and evaluated.   Awarding the winning bid must take place according to those pre-determined criteria, and be well documented in case any of the bidders decide to submit a complaint. The evaluation criteria may consist of:

• Cost 
• The provider’s functional, technical and environmental qualities
  • Quality of the master plan 
  • Quality of the production units, its production capacity in different temperatures, energy usage, throwing capacity, noise, weight, etc  
  • Environmental certificats, etc. 
• The system’s operational qualities
  • Ease of operation and control systems
  • Automation
  • Education, service plans included etc.

At many venues the snow production needs to take place in marginal weather conditions, especially at startup times with mild and changing temperatures. These conditions will likely determine the choice of the system. A snow production system that functions well in marginal conditions will be relatively expensive to install and to operate. There are many provers in the marketplace, and it is important to thoroughly evaluate which system provides the best overall production. If the snow production mainly takes place in marginal weather conditions, the choice of system may be simpler.

Building and installation

After the tender has been awarded, the actual building and installation can start (an eventual water concession, although it sometimes takes time, should be awarded before any ground work starts).  The on-site work should be led by a project coordinator, who organizes weekly construction meetings and safety controls, writes protocols, creates and adjusts the schedules, etc. 

The chosen contractor will establish themselves on the site, and must ensure the workplace safety, hold regular safety inspections and in general make sure safety is considered for workers as well as for public or visitors in the area (good signage is important).   Normally a fenced area for parking, construction trailers and equipment will be required. A snow making system consists of many expensive parts that also need to be protected (pipes, pits, valves, hydrants, fan guns, power- and data cables, tools, etc)

During the installation, the pipes should be pressure tested to avoid discovering problems after the pipes and ditches are covered. Valves and power connections are usually accessible in the pits or distribution boxes, and can be tested at any time.   

Towards the end of the construction process, it is important to have planned the steps for the comissioning of the system and the “hand-over” to the venue owner or ski club. All installed parts of the system must be reviewed and checked, and initial training and start-up of the system must be planned (and done) together with the system supplier. The electrical components, pumps, valves, hydrants, production units and the automation software must all be parts of a detailed check-list.   It is also important to ensure that a sufficient warranty period is in place for all the main components (3 year warranty is quite standard).  

Specific advice for Cross-Country/Biathlon systems

To sustain or possibly expand the current level of Cross-Country skiing and Biathlon in the future, it will be necessary to install more snow production systems at existing and new venues.  These systems are unique from systems used at alpine, snow parks and ski jumps since the courses and therefore the water (and air) pipes follow undulating terrain.  This requires some customization.

If the water pipes are installed above the frost line, it is important to make sure the water in the pipes drains when not in use, with pits for drainage at low points as well a air vents at high points. Pipes and cables must be installed according to the national code (see photos above) – with sand protecting the pipes, warning tape above the cables etc. such that the system will last for many years, and can safely be repaired if needed.

The work must be quality controlled along the way. For example, it is important to place the hydrants, pits and distribution boxes such that they will not cause any safety issues for skiers or the grooming machine operator.  All above-ground elements must be placed outside the ski trail as well as away from where an unlucky skier may crash and slide (for example, hydrants should be placed on the inside of downhill corners and not on the outside where a skier will naturally slide if out of control).  

It is also important that ditches, trails and side slopes are smoothened out with a back-hoe such that the soil edges are predictable for the grooming machine operator in the winter (an unnatural edge may ruin the snow surface with soil or gravel if the grooming machine blade “finds” it). 

On the Cross-Country/Biathlon stadium it is important that the hydrants are placed around the perimeter and not in the middle (where they always will be in the way of grooming and skiing). Since the area in the middle of the biathlon shooting range also needs to be snow covered, it is important to remember to place a hydrant nearby.

A stadium is often used as a snow depot during early season (since it is easy to create large piles of snow in an open, flat area), and later transported out on the courses. It is an advantage if the surface is paved (with a sligh 1 – 2 % gradience for drainage) such that gravel or dirt is not mixed into the snow when dozed into trailers for transportation and distribution. 

When deciding the detailed placement of the hydrants and the production units, it is important to consider the normal wind direction. Fan guns and lances should be placed such that the snow is produced and blown with the wind.

• Placing the hydrant at the correct side of the trail is important, since otherwise the snowmaking hoses may need to cross the trail and be in the way of both skiers and snowmobile/machines
• Hydrants and production units should be placed above the trail (uphill side) if possible such that the snow can blow a longer distance

Specific advice for alpine systems

Snow production systems for alpine venues are normally planned, designed and constructed by established and commercial ski resorts, although a few small alpine venues are operated by municipalities in certain countries (for example Norway). Large automatic systems are usually designed by resort planning- or engineering companies in cooperation with large snow production component providers. However, some smaller or medium-sized alpine venues may still consider planning expansions or new snowmaking areas on their own, and gathering good advice might be a smart investment. 

• Correct placement of the fan guns or snow lances will considerably reduce the need for grooming machine work less pushing of snow
• It is important to consider the normal wind directions and local conditions (ask local residents) before deciding where to install the snowmaking pipes, hydrants and producion units. Cold winds normally come from the north and follow the valley bottoms.
• If the snowmaking pipes, hydrants and fan guns/snow lances are installed in the wrong location, the wind may blow the snow backwards and bury the fan guns/lances. Portable fan guns then need to be pulled far out onto the slopes and will require extra long hoses and power cords, as well as additional labour. The production will be slowed down, especially in the case of permanent fan guns or snow lances. 
• Portable fan guns should be placed such that they can be moved backwards and up the hill without burying the hoses and the gun itself (with the produced snow). It is important to avoid moving the fan gun to an area that is newly snow covered (the figure below illustrates how a fan guns should be used and moved).
  
  
• Permanent fan guns and snow lances require minimum hoses and will not be obstructive, however, they will only produce snow close to their position and may create lots of work with the grooming machines if the slopes are wide
  • by needing to push the snow across the slope to cover the whole ski course
• A fan gun/snow lance installed on a tower will increase the snow production since the water droplets will have more time to freeze  
• The distance between each of the hydrants and fan guns/lances should be adjusted according to the width and steepness of the hill, and according to the estimated hours the temperature is condusive for snow production
• Hydrants and fan guns/snow lances should be aligned with other technical installations (light towers, etc) to reduce the number of obstructions for skiers
• Ensure that the snow does not land on power lines, lift installations, buildings or other structures that may be damaged by the weight of the snow
• Local and residential noise restrictions may affect the choice of placement, the hours available for production and even the chosen model of fan gun (some are more quiet than others).  
• Portable fan guns must be anchored in place to avoid movement due to the forces during operation; this is especially important in steep terrain.  

Specific advice for Snow Parks 

Most venues with a Snow Park require an extra high capacity snow production system due to all the elements that are being built by snow.   

The systems needed at the snow parks are standard production units, but the planning and placement of hydrants and permanent fan gun/snow lances are a bit unique.

• A snow park does not require equal capacity its entire length, so the hydrants and fan gun/snow lances should be placed where the demand is high and such that the snow production is finished at the same time in the different part of the course 
• Flat sections planned for small elements, such as rails and boxes need less snow than steeper section used for jumps. Sections with uneven ground or with sideslopes need more snow than where the course follows the fall line.
• The elements are often built on both sides of the course, so the pipes and hydrants should enable this. The elements require large amounts of snow, and the grooming operators would want to minimize the amount of time spent on moving the snow in place.
• Always place the hydrant or fan gun/snow lance where the snow is easily acessible for the grooming machine, and near where the elements are planned. It is also best if the snow can be pushed downhill towards the elements. If any elements are built by soil, the hydrants should be placed a bit above the element, or in the middle of two elements if they are aligned. This makes it simple for the grooming operators to access the snow and push the snow downhill. In this way, the snow production can also take place during the season if needed.
• Ses KUD/Norwegian Ski Federation manual https://snowpark.no/bygge-elementer/ for more details and videos.

Specific advice for Ski Jumps

Ski jumps are relatively similar and can therefore have a fairly standard snowmaking system design. It is foremost the landing hill and outrun that require snow. Since the landing hill is so steep, permanent snow lances are normally installed, while fan guns are often used on the outrun. The lances are placed evenly down the landing hill (starting on the knoll), and “with” the wind such that the snow blows onto the hill. On the outrun, fan guns are used since they have a larger capacity than snow lances (1 – 2 snow fans can produce enough snow in a short time).  Hydrants and power boxes must be placed outside the outrun perimeter safety fence to avoid any accidents.    

4

The production process

Startup of a new system must be done together with the system provider. The largest and most technical components; the electrical system, the pumps and the water delivery system must be tested first. The water does not need to be filtered and clean, but can not contain elements that will clog the filters in the production units. All pipes must therefore be well flushed before the fan guns are attached and turned on. 

The production process will depend on if the system is distributed along the courses or is a central system producing snow in a large depot. For a central system the ground surface should be paved such that rocks and sand is not mixed in with the snow when it is lifted into the trucks or trailers for transportation.  The amount of work for the snow production part is less for a central system, but the cost and logistics affiliated with the transportation can be both expensive and difficult. 

The work load for a distributed system will vary with the size of the system, with the operators’ expertise and the level of automation. Because of the risk affiliated with the high water pressure, cold temperatures, etc. it should always be at least two persons present during operation. It is always necessarry to check that the fan guns are working as expected, and that the snow is produced on the course and not in the forest or an adjacent field. In windy conditions it is necessary to check and adjust the angle and direction of the fan guns regularly. If the system or a fan guns stops, it is necessary to immediatelly disconnect and drain the hoses such that they do not freeze. 

For a well functioning snowproduction system it is also important to have a warm building or garage where the operators can get warm in between their inspection rounds, where tools can be stored and where hoses and other equipment can de-ice and dry out. Additionally, a toilet must be available.  

Since production equipment easily freze in cold temperatures, is it important to have tools that can be used for removing ice, such as pick-axes, shovels, propane torches, heat-guns etc. Water repellent and warm boots, gloves, pants and jackets are also necessary for working outside in the cold.

Safety

The snow production must take place following the advice in the manuals provided with the equipment being used, and according to the operational safety routines for the venue. In Norway, national guidelines for operational safety routines in alpine venues have been published (www.alpinanleggene.no). Much of these are also applicable for Cross-Cuntry and Biathlon venues.

Strict requirements for staff education must be implemented, and the health and safety for personell must be prioritized. Operational staff must verify and sign that they have read all safety manuals and instructions provided for use of fan guns and snow lances, compressors, pumps etc.  

For smaller venues that are operated by ski clubs it is extra important that volunteers, parents, etc. recieve proper operational training and that the club’s insurance covers any insidents or accidents (NOTE: It is important to check that volunteers and retired persons are covered by the insurance).

Before the startup every season, the snow production system must be checked for potential damages, water leaks etc. 

• check all pipes by starting compressor and water pump 
• check if any repair of hydrants or valves are required
  • when controlling air hydrants it is exra important to be careful  
• water intake must be cleaned 

Operational instructions covering tasks before and during daily operations must be written (and followed).

• Before operational start:
  • Control that snow and ice are not blocking air- or water hydrants  
  • Control that all valves are working properly 
  • For manual start of fan guns it is normal that two persons are involved; one will regulate the water supply, the other will stand below the fan gun/snow lance to control the snow quality  
  • For hydrants that are not used, the handle should be closed and locked  
  • The radio batteries must be charged before each shift is starting 
  • General control of pump station and compressor station  
• During operations:
  • The snow production system must always be watched when in use
  • Unauthorized persons should not be allowed inside the snow production area
  • If the snow production takes place during the venue’s opening hours, the production area should be roped off, and the public/users must be informed that snow production is going on
  • Pumps, compressors and fan guns/snow lances will start automatically if this option is set (in an automatic system)
  • For manual start of snow lances the water hydrant should first be opened by 1/2 rotation of the handle. Immediatelly when the water comes out, the air hydrant should slowly be turned on to a fully open position.   
  • Control or move fan guns. Use the grooming machine to move fan guns in steep and icy sections.  
  • Control all hoses for leaks. Exchange damaged hoses and mark the leak by tying a knot at the location. 
  • At startup, all attachments must be checked before opening the hydrant 
  • When opening the air/water hydrant, the snowmaker must stand behind the hydrant and be in radio- or visual communication with another staff person.  
  • The snow production must the stopped if there are safety concerns related to high wind, fog, icing, injuries or damages, functional problems etc.
  • The staff at the hydrants and fan guns should communicate using standard and agreed on signals:
    • Visual communication: Right arm ready for startup, arms in cross to mark stop  
    • In the dark at night: Green light for start for start, red light for stop
    • If visual communication is not possible, radios with headset/headphones must be used.  
  • Precise information must be given to the next/on-coming shift
  • During operation the hoses must continuously be checked to avoid rubbing against sharp rocks, etc 
  • Be aware of the risk of unexpected movements – or even somersault – of the fan gun due to high wind, steep terrain, sudden change in water pressure or movement of the hoses. 
  • Make sure that any vibration in the hydrants are minimized  
  • Never be alone if a fan gun under pressure needs to be moved
  • Move or adjust the fan gun often, preferably every 1 – 2 hour, such that moisture can be released  
  • Produce the snow downhill and in tail-wind  
  • Let the air-droplets/snow get as much air-time as possible  
  • If a hose becomes jammed, for example by icing, the production must be stopped until the pressure is lowered. If this takes too long time, a puncture or rapture may happen. 
  • Always follow the plan for which sections of pipes that are being used. NOTE: Write down which fan guns that should be moved (and other instructions) for the next shift.

Snow quality

Production with fan guns and snow lances both require careful mixing of water and air. It too much water is supplied, the snow becomes wet and can easily freeze. It the air supply is too high, the snow becomes too dry.

• For manual systems it is important to watch for changes in temperature, since this will require adjustments in the amount of water needed for optimal snow production and quality.
• The temperature and fan guns should optimally be controlled and checked once per hour.
  • Snow lances do not need to be adjusted since they function on a different operational principle.

The quality of the produced snow is categorized on a scale from 1 – 9, where 1 is powder snow and 9 is sleet or almost rain. By holding a straight arm below where the snow falls (and catching it on the sleeve) it is relatively easy to see where on the scale the newly produced snow is. Normally the snow should be produced with quality 5 or 6.

• The density/weight for snow with quality 5 is 300 – 400 kg pr m³

Production for Cross-Country/Biathlon

For a distributed Cross-Country/Biathlon system, the snow is produced in 3 – 4 meter high piles (or “whales”) along the courses. After drying out, the piles are pushed out by the grooming machines.  Optimally, the snow should be produced at least every 50 meter, but the grooming machine can push the snow over longer distances is needed (up to a couple hundred meters).  

Process (with photos from the new 2022 Olympic venue north of Beijing): 

• Place the snow fans along the course and in the stadium, attach power, data cable and hoses (move to the next hydrant when finished etc)
  
  
  
• Start the pumps and fan guns, produce snow on the 6 – 8 meter wide courses by regularly moving/adjusting the fan gun according to the wind direction
  
  
  
• Create snow piles ca. 3 – 4 meter tall, and let them dry out for ca. 1 – 2 days
  
  
  
• Push the snow piles using the front blade, and create a ca. 30 – 50 cm deep snow surface
  
  
  
• Groom the course with the tiller and create a nice corderoy surface
  
  
  
• After the snow has “settled” and hardned a bit, the ski course is ready for use 
  
  
  

There is no requirement or standard for the snowdepth of a course or a stadium, but due to heavier use, the stadium should have a deeper snow layer. For biathlon ranges, the shooting ramp requires special grooming (often manual) since it needs a harder surface and a standard depth (30 cm) all winter long.  

Production in alpine venues

Snow production must take place acording to the user manuals for the equipment in use, and according to the venues’ safety routines.  In Norway, national guidelines for operational safety routines in alpine venues have been published (www.alpinanleggene.no). 

For all alpine venues it is important that the instructions and requirements in the snow production operations plan are followed, and that the plan includes clear guidelines for what the control before and during operation, as well as routines for the different shifts (night, morning, afternoon).

For alpine slopes there are no rules regarding the depth of the snow layer. The depth can vary from section to section within the ski area. Where wear and tear is common, especially in steep sections, a thicker layer should be produced. Skiers will often stop on the upper edge of a steep section, and this causes increased wear and tear (the skis also emit energy/heat). The grooming machines will also have a tendency to push snow off these edges.

It should also be given consideration to sections where training and competitions take place, and where gates (especially slalom) must have at least a 50 cm snow layer. Use a drill and auger to check the depth. The table below provides guidelines for depth in different category slopes.   

Category slope	Requirements
Green/Blue	20 – 30 cm hard packed snow
Red/Black	40 – 50 cm hard packed snow
Competition	50 – 70 cm hard packed snow

When the snow is produced during early season (when mild weather is still expected), it may be best to produce in large piles. Snow piles are very resistant to mild temperatures and rain.

When snow is produced in cold and stable weather, and a race arena is being prepared, it pays off to produce in thin layers to secure a high quality and to cover a large area as fast as possible. This means that the fan guns must be moved often.   

Freezing

Snow production is about treatment of water in below freezing temperatures. Standing water in those conditions will freeze to ice, so it is important that the water in the snow production pipes and equipment is constantly moving. It is therefore important and neccessary that water is flowing or drained at the end of every “dead end” water line. To make full use of all the water, it is therefore smart to place a fan gun at these locations. It is also important that any excess (drained) water is piped or ditched to a nearby creek, and is not just freezing to ice on the course or ski slope.  

Problems with freezing (or ice) in the fan guns themselves are normally caused by wrong alignment of the fan gun in relation to the wind direction. If the fan gun blows snow into the wind, it will become covered with ice and create big operational problems. For example, a fan gun will stop operating when ice builds up on the fan and the internal mesh behind the fan becomes covered. If a fan gun ices up, the hoses will soon also ice up.

Removing ice from the fan gun is done by carefully using a torch or by trying to chip off the ice with an appropriate tool. Often the best solution is to bring the fan gun inside the maintenance building/garage and let it completely thaw.  

The hoses will not freeze/ice as long as the water is moving. When the snow production stops, the hoses must be drained by laying them along the ground on a downhill gradient. When starting up again, water should first be sent through the hoses before connecting to the fan gun. This will avoid that ice particles clogg the fan gun’s filter. 

Air hoses in high pressure systems can often build up an internal layer of ice due to the condensation. This can be removed by connecting the hose to the water hydrant and letting water run through the hose for a little while. It may be beneficial to regularly swith the hoses used for air and water (use air hoses for water and vise versa). Running water will “eat” ice. 

Production in Snow Parks

When the snow park is designed and it is time to produce and push snow on the slopes/course, the following principles should be followed:

• A clever procedure when building a snow park is to first produce enough snow to cover the surface of the course, and then produce the snow needed for the elements that will go on top. The most important reason for this is that all types of elements require an even and straight snow surface to start building on. It is also important to ensure that there is enough snow in between the elements. So, the first step is to produce and groom a straight base layer such that the elements can be optimal.
• The produced snow must have a moist quality such that it can easily be pushed as well as provide enough grip for the grooming machine when it is building the elements.
  • The snow is too wet if it becomes ice when freezing or drying out. The snow is too dry when the machine starts spinning or is difficult to push. It will take more time to build the elements when the snow is dry. 
• The snow should not be produced exactly where the elements are planned.
  • There must be room to work the snow. The machine must first crush and mix the snow before pushing it in place. This will create an even snow quality and avoid sugar snow or uneven layers in the finished element. The snow should be homogene with an even consistency from top to bottom. 
• It is simplest and cheapest to produce and push the snow from a location above the planned element  
• It should be enough space between the planned element and the produced snow for the machine to crush and mix it, as well as moving it without needing to change the direction of driving.
  • If the snow pile is too close to the planned element, it creates extra work by needing to move the snow in several turns and directions.
• Ca. 10–15% of the element’s total snow must be produced or pushed from below
  • with exception of small elements such as blue jumps (rarely needed)  
  • The snow that is placed below the element is used to build up and even out the landing and transition area after the main part of the element is built from above 

Production on Ski Jumps 

For smaller Ski Jumps the inrun, landing hill and outrun must be snow covered. In larger and modern hills the inrun is created by snow slurry or water that is cooled down to ice. The inrun track is then cut by the mechanical track setter.

For smaller hills it must be decided if the snow should be produced in a snow pile at the bottom or directly along the hill. To take advantage of a early days with cold tempratures it may be smart to produce in a large pile. For large hills it is normally no problem to produce snow directly on the hill.

The reason for considering this question is that wind will always blow snow off the hill and create some loss. Blowing snow may also cover and “ice up” stairs, bleachers, guardrails, equipment etc and create lots of extra snow clearing work.

The depth of the snow on the landing hill is determined by the homologated profile of the hill – the normal depth is about 30 – 45 cm.  It is important to not produce too large of a pile of snow on the knoll (with the purpose of pushing downhill). Due to the steep gradient the pile may avalanche, rip the snownet and create safety issues for the staff. It is important that the produced snow is not too wet since this will build a wet layer between the surface and the snow and possibly create another avalanche situation.

The best method for placing the snow correctly with a grooming machine is to produce and push the snow from the bottom (K-point) and up.  

When laying down snow on summer hills (snow on top of plastic) a few special methods must be used.

• A strong net must be strung and anchored both on the top and on the sides. Several 2″ x 4″ wooden planks are place across the landing hill. These are fastened by parallel wires. To ensure that the planks are well covered, an extra thick snow layer is used.
• The wires must be well anchored due to the weight of the snow (especially on a slick surface).

The newly produced snow must be dried out a couple of days (but no more than 72 hours) before being groomed. Artificial snow often contains more moisture than natural snow, and will require more work and time to distribute and groom.

5

Summary

The following factors will influence the snowmaking:

Wetbulb temperature	Wetbulb temperature is calculated from air temperature and relative humidity.	The wetbulb temperature is directly related to the snowproduction efficiency.
Throw distance/Drop height	For fan guns we use the teminology «throw distance», while for snow lances we say «drop height»	The longer throw disatance/drop height, the more time the water droplets have to freeze to and become snow
Water capacity	The water capacity for the fan gun is dependant on the water pressure and the size of the nozzle/number of nozzles that are open.	The higher the water pressure , the more water is pushed through the nozzles and the better the atomization of the  water is!

Water temperature	The water temperature is dependent on its origin and method of storage.	The higher the water temperature is the longer it takes for the water to freeze after it is sprayed out into the air.
Wind	If the wind increases or turns, the snowmaker must carefully watch to prevent the units from icing down.	Changing wind condition and headwind can lead to icing and damaged equipment, as well as possible damaged infrastructure such as lifts, light towers etc.
Loss	Loss of snow volume may be due to: – Evaporation – Melting/ablation – Too much water – Wind drift	Except from ablation/melting due to temperature, sun or wind, it is the staff’s responsibility to prevent that the conditions worsen due to these factors.

6

Cost – examples

To calculate the total cost for traditional snow production, the following elements should be included: 

• Cost of investment/construction and depreciation (normally over 10 years)
  • The planning and construction of a snow production system will vary with the size and amount of ground work required. Larger systems may cost 1,5 mill EURO or more, while smaller systems can be done inexpensively by using volunteers and sponsored services. Here are some elements that should be considered for cost:
    • Administration and planning work
    • Feed pump (from water source to pump house)
    • Construction of storage tank or reservoir (and possible blasting)
    • Pump house with pumps and compressor (if needed)
    • Distribution pits with valves (including installation and materials)
    • Contruction of ditches for water, air and power
    • Innstallation of pipes and power
    • Cost of water/air pipes and power cables
    • Distribution boxes for power
    • Misc. materials (gravel/rocks, sand, osv)
    • Snow production units (fan gunsm snow lances)
• Cost of labor for production
  • The number of hours it will take for produce 10 000 m³ of snow in teh example above rom Stjørdal (with average wet bulb temprature of ca. -6.8 degrees Celsius) can be estimated by using the formula below:
    
    Hours of snow production = planned snow volume / (capacity per fan gun * number of fan guns) 
    
    For Stjørdal, with 35 m³ snow per hour per fan gun (se graph above) and 5 fan guns it will take a total of ca. 57 hours to produce10 000 m³.  With two person per shift (estimated to 35 EURO per hour) this will cost ca. 4 000 EURO. 

• Cost of electricity for pumps and fan guns
  • A standard fan gun used ca. 25 kW, while the fan gun’s energy consumption per m³ produced snow depends on the wet bulb temperature. There are established formulas for this from each manufacturer (see example below):
    
    Energy consumption (kWt/m³) = 22,027 * (-X^-1,078)
    X = wet bulb temperature
    
    The following table (baseed on the formula above) can be used for estimating the energy consumption:
    

    Wetbulbtemperature  -3 degrees  -5 degrees -6,8 degrees  -8 degrees  -14 degrees kWh/m3 6,74 3,74 2,79 2,20 1,27

    
    Total energy consumption for 10 000 m³ snow (if wetbulb temperature is -6,8 degrees C) is 27 900 kWh.   
    
    A large pump (or two smaller pumps) with capacity of 150 m3 per hour will have an energy consumption of ca. 300 kWh. 
    
    The cost of energy for pump and fan guns are (price per kilowatt-hour is ca 0.115 EURO): 
    Pump (57 x 300 x 0.115 EURO) = 1 967  
    FAn guns (27 900 x 0.115 EURO) = 3 209 
    Total: = 5 175 EURO  

• The cost of the water depends on if municipal water is used (and needs to be paid for)  

• Transport of snow:
  • By experience, the cost of transportation of snow (in Norway) is ca. 2,5 EURO/m³ (rental of dozer, truck with trailer, fuel, driver).  For 10 000 m³ snow this will amount to ca. 25 000 EURO.  A trailer takes ca. 10 m³, so ca.1000 load are needed to transport 10 000 m³. 
    
    The cost of transport will vary from venue to venue. For municipal venues the transport must take place using public or in-house providers, while smaller ski-club venues can use sponsored equipment and labor. In any case, it is important to consider where the snow is produced and how heavy vehicles can reach all parts of the course. 

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