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| Preparing for rain and a period of thaw; What is the best approach to prepare for approx. a week of warmth and possibly some rain? | |
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| Tweet Topic Started: Jan 26 2013, 05:46 AM (1,423 Views) | |
| madsdyd | Jan 26 2013, 05:46 AM Post #1 |
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Hi there. Our club recently got a grooming machine, and have started using it on our small slope (alpine skiing). This is in Denmark, which is very marginal wrt. snow and frost. We do have about 10 cm of groomed snow now (yes, it is not a lot) for this weekend. (We typically only open in the weekend). The weather forecast talks about 2-3 degrees of warmth, for the coming week, and a high possibility of rain. So, my question is; how should we prepare for the week of warm weather (besides praying for frost :-). Should we: - Groome the slope and just let it rain on it? - Collect all the snow into a couple of piles? - Something else? Any advice greatly appreciated! Kind regards Mads |
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-- Snowmaking and grooming in extreme marginal conditions: Thats us! Youtube videos | |
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| PB260 | Jan 26 2013, 08:51 AM Post #2 |
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Should we: - Groome the slope and just let it rain on it? - Collect all the snow into a couple of piles? - Something else? Any advice greatly appreciated! Mads I replied to your earlier post and what I said then still applies. From looking at your web cam it is obvious that you do not have enough snow to operate your groomer without doing damage to your remaining snow pack. If you dig up dirt and vegetation and mix it with the snow you will only lose more snow. Every time that you work the snow you will break down the bonds in the snow and you will create friction and heating in the snow pack which will further reduce your snow amount. Pushing all your snow into a pile before the rain may well save some snow but the amount that you will lose during the dozing into a pile and back out onto your slope will likely be much more than you will save. Rain does not do as much damage to the snow pack when it falls as it does after it is concentrated under the snow pack. Mads you face a very difficult situation. You need to take a long term view and plan the development of your ski slope so that it is best suited to operating with minimal amounts of snow. In the conditions you will experience the paramount issue is drainage. Regardless of whether you get rain or not you will always have snow melt at the base of the snow pack creating water that will follow the drainage lines and become concentrated where it will erode your snow pack from below. The water may also lie at the base of your ski slope waterlogging the pack and causing more substantial loss there. Controlling drainage may make the difference between having enough snow to groom and not but it is unlikely that anything can be done until summer. Of great importance is the location and aspect of your ski slope. These are probably things that will be difficult or impossible to change but if your slope faces south it is probably doomed and you should ask yourself are there any other possibilities. Next is snow farming and then snowmaking. In some situations snow farming can make a huge difference to the amount of snow you have to groom without inordinate expense. Snowmaking is extremely desirable if you have the money to pay for it. In Australia it makes the difference between having enough snow for viable slopes and not. Lykke til! |
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| madsdyd | Jan 26 2013, 03:54 PM Post #3 |
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Hi again! Thanks again for your answer. I finally got around to write an answer to the other thread. We did take your information/answer into account (well, we tried to, we are very much adapting to a whole new situation having a grooming machine now), I just did not manage to get back to you. Sorry about that! You are right about the situation as you can see it on our webcam (http://www.roskildeskiklub.dk/skibakken-i-hedeland/webcam.aspx). We have polluted the snow with dirt from the ground. I have a couple of excuses (but we are guilty :-). We have snow making facilities, and used them Thursday and Friday (night) to produce snow. We had monitored the weather report, and we expected the conditions to be suitable to produce a reasonably cover in 24 hours. Everything went well during the first 12 hours (my shift, btw, in daytime from 05:00 to 17:00) and approx 50% of the slope was covered in about 20 cm of reasonably dense snow. Then the next team took over.... the details are sketchy, but "something" went wrong. They had several hours of -14C (I operated in -9 to -3) but did not manage to produce much snow. They did manage to create two large spots of clear ice though... and aborted early. When I learned about it Friday morning, I got extremely low. Friday midday the situation was bad. We had announced to several thousand people + local media that we were going to open Saturday, and we only had snow on 50% of the slope + ice on a couple of 100 m2. Conditions were no longer to produce much snow (approx -3 / 90% - only one of our machines can run in this, and only a single ring). I could not inspect this myself, as I managed to severely sprain my ancle on my own shift (sigh), and my foot (still) is about 2-3 times its normal size... So, they did what they could, and moved snow around, trying to distribute it on the areas that are most "used" when people ski the hill. This is probably something that would have been doable with an experienced snow groomer - we have only very green groomers. Still - they actually managed to save the situation, to the extent that we were able to open today. The webcam (and the hill) looks awfull, but if you go inspect the grim grey areas (I was there today), it is actually about 99% snow, and only about 1% dirt. This just underlines your point about *not* polluting the snow, as the effect is "insane", both visually and probably also with the albedo. These are the "grey" areas on the webcam (probably not possible to see the difference, but in real life there is a difference). Of course there are also areas where there are no snow at all (more brown in color), and some areas with ice. One of the reasons the cover got polluted is because we used the tiller. I am not sure we should have done this, but they judged they had to. Of course the cover was too thin, but we also think that the ground had a number of small bumps, and that the tiller levelled some of these and polluted the snow by doing it. We hope - perhaps in vain - that there will be less of this in the future (as we have levelled some of them now). If you experienced this snowcover in the alps, or Norway, you would probably call it totally unsuable. However, much of the areas (the white ones) are actually some of the best (not thickest though) snowcover we have ever had: compact snow, with a hard, but dry (not icy) surface, and 5-10 cm in depth. The grooming machine have been wonderfull where the cover (of artifical snow) was sufficient. There are no doubt in my mind, that this cover would have been able to withstand the skiers for a much longer time than it usually would have been able to. (Was it not for the rain looming over the horizon). So, this is the paradoxical in our situation today (tonight): - We had the conditions to create a great snowcover, but messed up the snowproduction and did not have a cover at all on 50% of the slope. - One of our teams did wonderfull work (given the situation) and saved us. - Parts of the cover is some of the best snow we have ever had (not the most, but the most solid/hard cover). - We will get a few cm to freshen up the snow tonight (but are not going to groome). - We will get another 5 cms tomorrow night - Then the weather will change, and we will get probably at least a week of warm weather. As I read your answer to this post, we should probably do nothing about it now (We may just use the current snowcover to practice our grooming "skills"). Also: If I read your answer correct, you write that it is very important to be able to drain water, even while the hill is covered by snow. This is something we need to consider. We already have some water drains built into the slope, but I believe they are mostly to drain ground water, not water from the snow cover. I will take this up with the club. Thanks again for your kind advice. Our sloope migth seem like a crazy project for people from parts of the world, where there you get a lot of snow - but this is what we have, and we try our best! People enjoy it, we enjoy it - and that is what counts for us :-) |
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-- Snowmaking and grooming in extreme marginal conditions: Thats us! Youtube videos | |
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| PB260 | Jan 27 2013, 09:39 AM Post #4 |
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Mads in the short term you need to manage your snow making as productively as possible to maximise the amount of snow that you have to work with. I think that this is critical to your future. There are several parts to this and I’ll detail them later. Secondly you need to consider snow farming and snow harvesting as it seems from what you say that there is some scope for this. It may be that you cannot readily implement large scale snow farming without more infrastructure development but I imagine that some small scale snow harvesting may be possible. I need to know more about wind speed and direction in relation to temperature and precipitation to comment more fully on this. Thirdly you need to manage your grooming operation closely to minimise damage and to maximise snow retention and the durability and skiability of your slope. Sometimes it is better for the long term to not groom, especially in marginal temperature or snow conditions. A groomer is a dangerous weapon in the wrong hands. Lastly you need to establish a long term development plan that addresses the limitations imposed by your terrain and climate, takes account of your financial constraints and measures the potential for demand growth should you achieve effective management and operation of your ski slope to it’s comfortable carrying capacity. Mads do you have the financial resources to buy a new snow gun immediately? What about for next winter on a lease? If you do, you need to get some demonstration machines and start making some snow so that you can find out which one is most suited to your conditions. A new machine may produce much more snow than even your good machine and a demo machine or two could be producing snow for you now when you really need it. Here we seldom see temps below -5°C and humidity’s are often above 80% but sometimes they drop below 20% and then snowmaking is very effective right up to + 4°C. The key is humidity and the wet bulb must be below -2°C. Techno Alpin and Latemar are guns you should consider for marginal conditions. The alternative to a new or demo machine is to get the best out of your existing machines. Have they been serviced? Are the filters clean? Do you flush your hydrants before every use? Water mains have large amounts of sand, silt, rust and other detritus in them and it is often disturbed when a hydrant is opened. I have seen this render a snow maker unusable and producing only dirty rust coloured ice. Sound familiar? Do you have the manuals for your guns? Are you and your crew very familiar with the operating procedures and the need to constantly monitor snow production and adjust settings in order to produce the appropriate quality of snow? For your current conditions you need bulk heavy snow to build base. Snow makers need to spend time under the stream of snow checking snow quality. Do you know about maximising hang time by using towers or mounting snow guns on snow cats? Are you using a nucleating agent (Snomax)? Do you know about curing your snow before working it? Letting the water drain out of it so the quality improves! Are you cooling your water? A compressor and some plastic pipe with holes in it could cool your water by a few more degrees to well below zero and increase snow production. You are correct in planning to do little during the warm weather. Your groomer should not be used until you have plenty of snow for it. You should concentrate on getting ready to make snow instead. Are the guns in the best condition and ready to operate? All your snow making crew need to study the operating manuals and understand them. You need to consider ways to make your best snow gun mobile and elevated. Can you get a used snow cat cheaply to mount the snow gun on? Then it will be elevated, mobile and all the hoses can be carried allowing rapid repositioning when the wind changes. The more of these things that you can accomplish the better your snow production will be. There are most likely many things that I’ve forgotten but they will have to wait for another time.
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| madsdyd | Jan 27 2013, 01:17 PM Post #5 |
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Thanks for your, as usual, very informative reply! Some of the points you raise, we are familair with. The point about flushing the hydrants is new to me, and something we really need to take into consideration. Our water ressource is a small lake. We do have several filters, but we are not good at cleaning them. :-(. This might actually explain why we sometimes have snow guns that ice over. We don't have any manuals for them - I am going to write some material based on what we know. I think we know a lot, but some of our operators either does not know, forget between seasons, or are not dilligent enough. Your points about leasing/getting demo equipment is taken. I would be interessted in knowing more about the water cooling using a hose, you write about. We almost always have wind, when it snows, typically 9-10 ms/s in -5C to 1C, with a humidity of 95%. In general we never seen humidity lower than 60-65% and that is only rarely. Re economics: This is really something we do because we love it, and want to allow as many people as possible to enjoy skiing close to their home (Danish skiers travel outside the country to ski "for real"). This gives us some limitations, but you are right, we need to focus on all possibly avenues for improving. I have only been part of the operations for three seasons, but my experiences, and what you write, makes me conclude that we need to put much much more focus on snow production (and snow farming). The best snowgun we have, is mobile and slightly elevated. You are right that we should focus on preparing for the next snowmaking. I will ponder all your advice, and put some of into writing. Thanks again. Mads |
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-- Snowmaking and grooming in extreme marginal conditions: Thats us! Youtube videos | |
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| madsdyd | Jan 27 2013, 01:19 PM Post #6 |
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Oh, I forgot: Why are the techno alpin and latemar guns better than the others? Do you have any idea of the price range on such guns? We do have some money, we are pretty conservative in our spending, and have been saving for a renewal of our lift system. Regards Mads |
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-- Snowmaking and grooming in extreme marginal conditions: Thats us! Youtube videos | |
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| undy | Jan 27 2013, 01:47 PM Post #7 |
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Mads, Your link above had one too many figures. Here's the link: Mad's WebCam Link
I don't want you thinking your work is crazy. Man, I'm doing the same thing, but on a hill on my farm, and for free. Over the past 2 years, we've only had about 10 days of skiing, because we're entirely dependent on natural snow. Right now, half of my hill is green/brown. That's crazy. But on the right days, it's like paradise. Think: private powder slope. That's why we do "crazy" things. (May we stay young enough to keep doing 'em for a long time to come.) I've skied now for nearly 50 years, but until 2 years ago, I'd really never given much thought to how or when to groom, etc. So I'm reading your threads with interest. I'm afraid I don't have much advice to offer you though. But it's great to have another downhiller here on the forum. Cheers, Paul |
| It is better to go skiing and think of God, than go to church and think of sport. Fridjof Nansen | |
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| madsdyd | Feb 1 2013, 07:38 AM Post #8 |
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Great to hear from you Paul! Crazy might be a to harsh word - but weird then :-) Kind regards Mads |
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-- Snowmaking and grooming in extreme marginal conditions: Thats us! Youtube videos | |
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| PB260 | Feb 2 2013, 01:43 AM Post #9 |
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Hei Mads, I hope that you’re out making some snow tonight and that it’s going well. I’ve been busy with some fire fighting as the wind carried embers from a nearby fire right into our Village and Ski Slopes on Thursday. It was looking bad for a time but three medium water bombing choppers helped out for a little while and took some pressure off. I spent too much time working on 30° slopes in scrub too thick to walk through easily and got very wet. Luckily yesterday the humidity went to 99% and the temp dropped to -2°C last night so the fires are not very active now. The Mount Hotham Skiing Company has researched extensively and also demoed various brands of snow gun at Hotham. They currently operate around 80 guns, most of which are Techno Alpin as these have been found to produce the most snow in our warm conditions. I believe that one Areco is used at the bottom of the valley as it produces a lot of snow in the cold temperatures that cold drainage provides down there. Here is the address of Hotham’s weather info to give you an idea of what we work with. http://www.bom.gov.au/climate/dwo/201206/html/IDCJDW3055.201206.shtml As you seem to have colder temps than us at times it is quite possible that Areco guns will work very well in your conditions. You also have the benefit of common language (almost) and possibly lower shipping costs with Areco compared to TA. The most important issue is snow production capability in the micro climate that exists at your ski slope. It is possible that an American Co. like SMI may produce the best guns for your conditions but if there is little difference in production in your climate then customer support from a local dealer is more important. Do you have a weather station and/or any detailed weather data? It may be helpful when contacting snow making companies. Alternatively is the DMI data available from a station that is quite close? There will be data from the Airport but it may be even more humid as it’s closer to the sea. Sorry but I don’t know current prices. It is years since I did and exchange rates are different now. I think that fan guns ranged around $80,000 AUD but the price has dropped over the last few years. A compactor bar would be better for much of your work as it will be hundreds of kgs lighter putting less strain on the frame of your cat and also allowing your tracks to dig into the snow less especially when climbing and/or turning. You can use your 2000 series tiller quite well when you have enough snow but you need to wait until you have plenty. When you get to that point ask me and I’ll tell you some of the issues to watch out for. When you park the PB200 the tiller should sit so that the comb is hanging freely and touching nothing. The resilience of the polyurethane comb will be lost if it is always left sitting flat on the ground. I use old 4WD tyres to support each end of the tiller with the comb sticking out behind. When you park the 200 close either the depth of cut ram or the second stage lifting ram and lower the tiller almost to the ground. Then place a tyre on each side under the cast iron side plate so that the front end of the side plate is above the centre of the tyre. Gently lower the tiller onto the tyre and pull forward just a little so that the side plate is supported at the back and its front end is down inside the centre of the tyre. This will kick up the comb and leave it free. Two blocks of wood can work if you prefer. It seems from watching your videos that there is scope for a snow farm at the top of your slope. Do you have access to the land above your lifts and what is the situation re planning permission for infrastructure development? Would minor earthworks be possible? Do you have truck access to that area? Is there winter access? If you want to experiment it would be relatively easy to erect some portable industrial barrier fencing there and you could get some idea of the viability of an extensive snow farm. Dr Ronald D Tabler was an authority on snow fences (and many other things) for decades. I first read his work in Ski Area Management Magazine I think in the 80’s. You can learn a lot from reading his published papers although none of them directly address snow farming for ski runs. (I believe) His snow fence construction manual is very informative Tabler, R. D. 1988. Snow fence handbook (Release 1.1). Tabler & Associates, Laramie, Wyoming. 169 pp. His web site is http://www.tablerassociates.com/ Aspects of snow fence design need to be tailored to each individual site and if you like I could talk you through the differences that need to be considered to establish a snow farm at your ski slope. Got to go to a Fire Brigade meeting so ha det bra!
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| undy | Feb 8 2013, 06:49 PM Post #10 |
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Hey Mads, if you want to feel real good about you efforts; I made the first (and only) runs of the season today at "Ullr's Gulch". It was about 6" of heavy powder from yesterday, over a few leftover inches of ice underneath. I had to be careful with balance, lest I'd break through the surface and sink. But balanced right, it was really nice skiing. That figures at about 20 hrs. of prep and 1 hr. of skiing, so far. And that's not including the major rebuild of the snowcat over the summer. The snowmobile refused to start, so that meant 3 hikes up and down the hill. Plus the starter solenoid on the lift was frozen solid, so I had to jump it with a pliers. Tomorrow it's supposed to be near 40 degrees and rain. Anyway, I hope you're having as much fun, and better luck! |
| It is better to go skiing and think of God, than go to church and think of sport. Fridjof Nansen | |
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| PB260 | Feb 16 2013, 07:47 AM Post #11 |
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Mads it looks like you’ve done well making snow lately but it also seems like you have a constant battle trying to maintain enough snow to ski on, never mind getting your PB200 out for some grooming. Have you had any luck with a demo snowmaker or even just a company that says their machines will make snow in your weather conditions? Earlier you mentioned how marginal your conditions are and I’m reminded of a cross country and snow play resort in Australia that has a lower elevation and unreliable snowfall. For the main toboggan slope they have a snow maker that can work in almost any conditions. It’s actually more like the ice making machine at your local pub except on an industrial scale. It makes large quantities of ice and then spits it out onto the toboggan slope. I believe it is expensive to purchase and to run but it may be another idea for you to consider. Another possibility is covering your ski slope with an artificial skiing surface. The Mount Hotham Skiing Company uses an artificial skiing surface on the load and unload stations of some of its chair lifts thereby saving an enormous amount of work trying to maintain skiable snow, at the correct height for skiers, under a drive station. The beauty of an artificial skiing surface would be that you could operate all year round and thereby potentially improve your financial position, enabling further development of your skiing infrastructure. It would be very expensive to set up your entire ski slope and your lift tracks but you could perhaps start with one lift and some adjacent terrain to minimise the cost. I have a very large concrete culvert under a highway that forms a link along a main ski trail and it held very little snow because water flowing through it would wash the snow away. I designed and constructed a very strong, very low and porous self draining deck which I also covered with a cheap outdoor carpet to facilitate skiing as soon as there is any snow. It has worked well for many years but the carpet is going to need replacing soon and I’d like to cover it with an artificial skiing surface so that I don’t have to spend so much time dozing snow into it. I’ve also suggested to the Australian Biathlon Association that they consider such a surface for the biathlon range as it has poor snow accumulation and retention due to sun exposure and wind scour. I do way too much work trying to maintain snow cover for them but so far they haven’t taken the hint. I’ve also suggested an electrically operated removable snow fence but they haven’t got back to me on that either. |
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| Kirill | May 28 2013, 07:09 AM Post #12 |
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PB260, could you explain this method of water cooling? |
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| PB260 | Jun 6 2013, 09:26 AM Post #13 |
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Kirill if you compress air it becomes hotter. When compressed air is allowed to decompress it cools. If you can cool your compressed air – with very cold winter air and then allow it to decompress as it is released from the bottom of your snowmaking pond it will cool the snowmaking water. Decompressed air cooling is used here and I’ve seen it used in Pennsylvania in the US where it took the liquid water temp to a little below freezing. Cooling of your snowmaking water could improve the efficiency of your snowmaking system. Ideally your snowmaking water should be as near to freezing as possible for maximum efficiency. Spray cooling systems – which operate by evaporative cooling of the pond water are another alternative. Commercial water cooling systems are available but they can be expensive so some people have put drilled plastic lines in the bottom of their ponds to create a simple cooling system using the expansion of compressed air. I see that you have a PB210 and I wonder what you are using it for. Alpine skiing and snowboarding grooming perhaps? Or is it Cross Country grooming? Can you provide more information about what you do or have you already done this when you joined Grooming Talk? A few years ago I was crew on a Squirrel AS 350 that was flying Russian geologists around the Vestfold Hills in East Antarctica, a little north east of the Amery Ice Shelf. I did some flying around Druhznaya IV (mostly I was on tiny Sansom Island waiting for helicopters to deliver sling loads) and Progress Station (in the Larsemann Hills) where the geologists were based. Some of them were from St Petersburg and also Kiev I think.
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