Installing a Ground Level Trampoline

If there’s one thing Morgan had wanted for Christmas it was a trampoline. You know the sort, the big blue ugly things that everyone seems to have rusting away in their gardens. He’s been wanting one for ages and we had always categorically said no. We had loads of reason why not as well.

  1. They’re ugly. I didn’t want such a monstrosity in my garden.
  2. They’re expensive (although not as expensive as we expected).
  3. It wouldn’t cope with the Ynyslas winds. They get blown around wherever they are but at Ynyslas it wouldn’t last a few days before getting blown away.
  4. It would no doubt destroy our conservatory or someone else house as it got blown away.
  5. With sand for soil there was no way of fixing it to the ground without concreting it in.
  6. Did I say they are ugly?
  7. It would rust in no time here. Anything metal does and when they rust, they are even more ugly. Until you’ve lived here you don’t know how fast the sand and salt can disintegrate metal. It wouldn’t stand a chance.

And that doesn’t mention the safety aspects – a friend of mine broke her back on a trampoline. Nor does it mention the amount of garden it would take up. And finally, they are just plain ugly!

No, No No, you can’t have a trampoline, there’s NO WAY we’re having one of those ugly things in the garden. It’ll rust, it’ll blow away and it’s just ugly. No Chance, No Way, you’re not having one.

Giving In

Needless to say – we gave in!

To be fair, we weren’t quite that submissive. It came down to the fact that it was Christmas and that’s all that Morgan had been asking for all year. As caring parents we’d love to get him just what he wanted so we tried to work out a way of doing it.

Ground Level Trampoline

This is where we hatched the plan of a ground level trampoline. You can buy special trampolines for sinking into the ground, but they don’t come cheap. A large one is about 2 to 3 times the price of one of the ugly framed trampolines that you can buy. By the time you add a netted safety enclosure that takes it up into 4-5 times the price. This put it out of our price range.

A sunken, ground level trampoline did seem like an option though.

  1. It would hopefully mean that it couldn’t blow way. Although, the netting safety enclosure would still be exposed to the wind. We did see some with enclosures that collapse for easy storage so there was a solution to that problem.
  2. The fact that it would be essentially buried in the ground would mean that the ugliness would be somewhat hidden.
  3. Granted it would still rust, but at least we wouldn’t be able to see the ugliness as it did – out of sight, out of mind.
  4. It may even be safer – there would be less height to fall from at least.
  5. Although it would still take up a considerable amount of garden, being at ground level it wouldn’t be too conspicuous. It may even save me some mowing.

Also, if we could get Morgan him a trampoline for Christmas it would be a brilliant surprise. Morgan had been wanting one for ages but our negative responses to his requests meant that he had given up all hope of getting one. We had offered him alternatives such as trying to find a local trampolining club. He was so desperate though that he had even down-graded his requests to a mini portable trampoline and some crash mats. The answer had still been NO. So, if there was a trampoline under the tree at Christmas he would be shocked and delighted.

Buying a Trampoline

The things we do for our children hey? We decided we were going to work out a way to get Morgan a trampoline for Christmas so we hatched a plan. I couldn’t see any reason why we couldn’t buy a normal framed trampoline for a fifth of the price of a ‘ground level trampoline’ and then sink the whole thing into the ground. I’m not really sure why the ground-level ones are so much more expensive? They seem to have much less to them and most don’t come with a safety net. The traditional framed trampolines however often do come with everything you need. We managed to find one on sale for £109 complete with a folding safety enclosure. It even came with a free ‘flash-zone’ feature composed of a flashing light under the bouncing surface.

It was soon ordered and hidden away ready for Christmas.

Burying a Trampoline in the Ground

Now, as I may have said before, these things are ugly. We now had one though so had to work out the logistics of burying it in the ground so as to hide it away. Luckily we know someone who has a groundworks company with plenty of diggers who could help for a small fee. We asked if he’d be able to help and he said yes. So that was it, after Christmas we would get Prys out to dig a hole and help bury the trampoline into the ground.

After some thought we decided that it would be even better if we could get it into the ground before Christmas so that Morgan could actually bounce on it over the Christmas holidays. So, now began the process of trying to bury a 10ft diameter framed trampoline into the ground. Not an easy task on it’s own, but trying to do it in secret right in front of the house just added to the challenge.

Prys came out the week before Christmas with his digger and made a start for me. It didn’t take him too long to strip back the turf and dig a hole 12ft in diameter and about a metre deep. The fact that our ground is just pure dune sand does make digging easy once the turf is removed. The garden now looked like a bomb-site though, complete with 12ft crater from the blast!

Bomb Site

Bomb Site – The beginnings of the hole

Once Prys had gone, I continued digging the hole by hand a little and tidied up. I then had to hide the whole thing (or should that be hole thing!). The groundsheet from our tent was just about big enough and some carefully laid boulders and planks helped keep it all secure. When Morgan came home we made up some story about Prys hitting a water pipe which meant he then had to dig up the entire garden to fix it. I’m not sure if he bought the story but not too many questions were asked.

The next day whilst Morgan was out with friends Anna helped me construct the frame of the trampoline. We did this inside the hole as that was where it would end up. It didn’t take too long and was fairly easy to do. Once again, the hole was covered up with the groundsheet and we popped into town to buy some more supplies for the project. 100m of 80mm perforated drainage pipe and a big bag of cable ties.

Constructing a Trampoline Retaining Wall

I wanted the trampoline to look as though it was properly buried in the ground, so now had to back-fill the hole to bring the ground level flush with the edge of the frame. This meant building a retaining wall so as to stop the sand from simply falling into the hole under the ground level trampoline. Initial thoughts were to fix corrugated metal sheets to the legs of the trampoline to act as an octagonal retaining wall. I decided against this though and came up with the idea of running flexible drainage piping around the outside of the frame instead. This would create a circular retaining wall, should be easy to do, would be relatively inexpensive and should last well too.

The 100m of flexible drainage piping cost £70, so the next day I was out there in the hole again. This time in the pouring rain. I man-handled the flexible piping into place and attached it to the frame with cable ties. It created a huge spiral retaining wall around the outside of the ground level trampoline.

With that in place I could start backfilling the sand into the void around the trampoline. As I did so, some parts of the retaining wall started to bow inwards a little too much. I decided they needed reinforcing somehow so added some wooden stakes and braces to hold them back. While I was doing this I also sunk some posts into the ground around the base of the frame. These were designed to hold the frame in place and stop the weight of the surrounding soil trying to push them inwards.

Now, the 4m diameter, 1m deep hole that Prys dug out with his digger in a few hours contained a fair amount of sand. If Google’s maths is correct, a 4m x 1m deep cylinder has a volume of 12.5 cubic metres (Volume of a cylinder = Ï€r²h). Damp sand apparently weighs around 2000kg per cubic metre. So, I now had 25,000kg of sand to move. Shifting 25 tonnes of sand by hand with a spade is back-breaking work. I managed it though and gradually backfilled the hole.

I also built up a rim around the trampoline frame so as to make the ground flush with the top of it with a gentle slope away from it. This was always the plan as we had to somehow redistribute the sand that had come out of the hole.

A Ground Level Trampoline

The next job was to attach the bouncing surface to the frame with the springs. Anna took Morgan swimming in town to give me another opportunity to continue with the project.  Attaching the trampoline surface was easy enough to do on my own. We now had what looked like a ground level trampoline in the garden.

Building a slope around the trampoline

Building a slope around the trampoline

The project was far from finished though as I still had a garden that looked like a bombsite and a huge pile of turf. I surprised myself today, managing to move the entire pile of turf and arrange it neatly around the trampoline. I had to attach a final circle of the flexible drainage piping to the top of the frame, leaving gaps in it so as to be able to access the joints into which the safety netting would attach. The turf had to be cut it into manageable segments too. Even these were back-braking to man-handle into position. It was however beginning to look good and the garden was looking a little neater. The ground level trampoline had turf around it. It looked to be an integral part of the garden.

Once again the ground level was covered up to keep it a surprise.

Cover Up

Cover Up

There was still quite a bit to do, but that will have to wait until after Christmas now so as not to ruin the surprise. I need to attach the skirt that covers the springs. I need to construct the safety net. The trampoline itself needs to be tested! The last few small piles of sand need to be raked over and levelled off somewhat too. I’m fairly confident that the grass will grow through this sand and that the turf will spring into life. So, by the summer it will look as though nothing has happened, except for the fact that the majority of the garden is now a bouncy ground level trampoline.

Taking up most of the garden

Taking up most of the garden

I can’t wait to see Morgan’s reaction on Christmas Day.

 

4 Responses

  1. Alan Cole says:

    Hooray, we pulled it off. We left a box under the tree with a note in it saying “Your main present was so big it wouldn’t fit under the tree so you’ll have to take a look in the big hole in the garden”

    Morgan excitedly put his shoes and coat on and we headed out into the wind to unveil the trampoline. It was a complete surprise to him and soon he was bouncing with joy!

    I think he’s pretty pleased with it and I still can’t believe that we managed to do that without him finding out or catching on!!

  2. Mum says:

    I’m guessing his pleasure made all the hard work and planning worth it. He certainly sounded pleased on the phone
    Well done xx

  3. Emily says:

    Hilarious that you got away with building an enormous Christmas present in the front garden! Amazing present.

  1. Monday, December 26th, 2016

    […] Day in the Cole household. The highlight being that we managed to successfully pull of the installation of a ground-level trampoline in the front garden and keep it a secret. Morgan was suitably impressed, surprised and […]

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Alan Cole

Alan is a Freelance Website Designer, Sports & Exercise Science Lab Technician and full time Dad & husband with far too many hobbies: Triathlete, Swimming, Cycling, Running, MTBing, Surfing, Windsurfing, SUPing, Gardening, Photography.... The list goes on.

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