Sustainable snowmaking systems for ski slopes and first snow tracks

Due to climate change, winter conditions have become more varied. Sometimes winters still come with a heavy snow cover, but mild and rainy ones are occurring further and further north. Many ski resorts are preparing for this by acquiring sustainable snowmaking systems.

In recent years, Sweco’s water management expert Heikki Pärnä has been working increasingly frequently with various snowmaking designs. ‘We create general and implementation plans, and carry out reviews for winter sports venues. We also help them with funding applications.’

The designing of a snowmaking system requires a highly specific set of skills in water management. Project by project, Sweco’s experts have gained experience in the unique features of different systems. Additionally, Pärnä’s ski jumping hobby is helping him understand the users’ needs.

‘Naturally, being a designer, I know the theory involved in watering a slope or covering it in snow, but it is a completely different thing to be standing at the tip of a ski jumping ramp with a hose and realising that the water pressure tends to fluctuate depending on the circumstances,’ Pärnä says. He has been taking part in veteran ski jumping for ten years.

Climate change increases the need for snowmaking systems

Finns take clean water for granted until problems occur, forcing people to see how much work a functional water management system actually involves. Designers are, therefore, constantly working on new ways to prepare for challenges, some of which are caused by climate change. As cities become more densely populated, the risk of flooding increases, while long dry periods during the summer months have an impact on the groundwater level. Snowmaking systems are used to prepare for fluctuating winter conditions.

‘Winter weather tends to vary a lot, particularly in southern Finland, and natural snow cannot always save the day,’ says Pärnä. In order for a snowmaking system to function efficiently, the temperature must remain at -5 °C, or preferably at -8 °C, for a sufficiently long period. ‘Many ski resorts use water cooling systems as a backup. That allows them to create snowy slopes and ski tracks, even when the temperatures do not drop that far below freezing.’

Water for snowmaking taken from the sea at Turku’s Hirvensalo

One of the first things that needs to be resolved when designing a snowmaking system is the sustainability of the water resource. Hirvensalo ski resort uses the local water mains to get the water required for snowmaking. ‘Using potable water to make snow for slopes is not financially or environmentally sustainable,’ Pärnä emphasises.

The City of Turku ordered a general plan for a new snowmaking system from Sweco, and the experts recommended the use of sea water. ‘Sea water can be even more suitable for snowmaking than freshwater, because humus tends to stain the snow yellow. That will highlight a slope’s elevation differences.’

Experts in fluid dynamics and route optimisation designed the best possible route for the water pipe, all the way from the sea shore to the ski resort, which is located on an island. The dimensions of the pumping pipes were also carefully calculated, because the snow cannons need a lot of water. ‘Large flow amounts cause significant pressure loss, and therefore the suction pipe must be large, 355–400 millimetres,’ Pärnä says. The end of the pipe was designed to have a filter to keep aquatic plants and small fish out of the powerful pipe that sucks in the water. The pipe may be installed through directional drilling.

Water also being sustainably drawn from lakes and rivers

Water can be sustainably resourced for snowmaking systems from other bodies of water, such as lakes and rivers. In Nurmijärvi, Lake Sääksjärvi, which is classified as a Natura area, was chosen as the source for a first snow track. ‘Before we planned the implementation, we carried out a Natura requirement assessment, and it showed that drawing water from the lake will only have a temporary effect of a few millimetres on the surface level,’ says Pärnä.

Careful calculations were conducted for the Natura assessment, and according to these calculations approximately 2,000 square metres of water will be needed to make 4,000 square metres of snow. It takes 40–50 hours to draw this amount, and therefore the system will only be running for a short period annually. ‘This is why we also designed a safe way of installing the system and taking it down,’ says Pärnä. The plan is to install the first fixed utility chamber by Lake Sääksjärvi and the second one next to the first snow ski track. While the snowmaking is taking place, a pontoon supporting a submerged pump will be floated through the chamber. ‘The second section was designed to be removable runs from the first snow track’s utility chamber to the high-pressure pump. This provides the pressure required by the snow cannons.’

In addition to bodies of water, snowmaking systems can use water from other sources. Sports club Kimito Sportförening from Kimitoön asked Sweco to create a survey plan for a first snow track’s snowmaking system. The original idea was to use water that collects in gravel pits. ‘However, you cannot predict the amount of rain, which is why we recommend the use of bore wells,’ Pärnä says. A sufficiently deep well is guaranteed to provide enough water, and mains water can be used as a backup.