We live on a mountain, a huge granite-filled monster of a mountain that seems to have filled our front and rear yards with its spawn. During some of our earthworks we’ve developed a few techniques for removing the rocks and boulders that we’ve encountered that we’d like to share with you Internet folks.
Firstly, granite is a very hard type of rock and particularly heavy, it’s 2.6 times heavier than water which means even the most innocuous looking piece of rock can quickly reach unmanageable weights very easily. The other problem you find with granite boulders is that they’re often round and don’t have holes or lips for picking up — it’s almost as if they’ve been designed with frustration in mind.
If you can’t pickup a boulder by yourself it’s probably too small to get help from another person.
Tip #1 – Pickup the Small Ones
The obvious starter tip, just remove the soil, pick them up and toss them. You’ll quickly learn out what you can comfortably pick up so stay within your safe working limits. A falling boulder hurts so I’d invest in some steel toe-capped boots. You can also use them to rest a boulder on as you squat down, get your hands underneath and stand up. Remember to lift with your legs and a straight back!
Tip #2 – The IKEA Bag Trick
IKEA sells these blue plastic shopping bags called FRAKTA:
They have a rated maximum load of 25kg (55 pounds) but they’ll easily take 50% more than that. For those slightly larger rocks that you can’t pick up just roll it into a FRAKTA bag, scrunch the corners up and use these two makeshift handles as your lift points. You may need a friend to pick up the bag but it works well.
Tip #3 – Use Rails
I’ve often use aluminium (aluminum) ladders as makeshift ramps for moving heavy loads around so I planned on doing the same with the rocks. In the end, I made my own ladder frames — I used two 16′ pieces of 2×4 decking lumber and installed five rungs of 1¼” poplar into the side rails. This was just a standard closet hanging rail that I cut up. I made two sets of rails as I needed to move rocks up to 30′. The rails are only around 12″ apart as I find this is the size of boulder that starts to become problematic to move.
Friction can be an issue when pulling a boulder up the rails and I was planning on installing some steel plate to counter that but I never needed to.
If I’m moving a boulder up to 50kg (110 pounds) I generally just flip it over and over using the rails as a smooth surface and ramp.
Tip #4 – Use a Boat Winch and a Marine Battery
I’ve tried using the ratcheting pulls but they’re slow, it’s far easier to use an electric winch. I found a boat winch at Canadian Tire for $99 that was rated up to 2,000 pounds. I mounted it to a large piece of MDF and secure it to a large tree using car towing straps that are rated up to 10,000 pounds. As you pull a boulder you have to bear in mind Newton’s laws of motions. As you pull a 200kg boulder the winch is pulling 200kg against the tree so make sure you pick large trees.
The next problem I hit was the car battery charger, the winch killed the battery within a few seconds of pulling. Apparently you need a deep-charge battery for extended winching, something that can deliver lots of power of an extended period. Car batteries don’t do that as they typically only have to deliver short bursts of power to start the engine. I invested in a $160 marine battery and a charger to go with it.
This solution works well and I’ve moved boulders up to 300kg without any difficulty. I have a heavy duty chain and the biggest carabiner I could find that I lasso around the boulder connect it to the 28′ of steel cable on the winch and pull.
Tip #5 – Bury ‘Em
Some boulders are just too heavy to pull upwards as the slightest grade increases the weight tremendously. In these situations I just dig a new hole for the boulder and slide it over or slide it down into its new home, out of my way.
Tip #6 – Split ‘Em
And finally, when you find those really, really huge boulders you need to split them. We had a 22,000 pound boulder in the front yard that had to be split. Dynamite works but it’s loud, expensive and could be prohibited if you live in a residential area. Splitting the rock with irons, feathers and wedges is just painfully slow. Jackhammers don’t do anything to granite, don’t waste your time — tried that one too.
Your best bet is to use an expansive compound like Dexpan or Ecobust. These compounds expand with up to 20,000 PSI of pressure and can easily split concrete and granite.
I just rent a Bosch rotohammer drill from Home Depot and a 1½” bit that can cut holes up to 18″ deep. The holes take up to 15 minutes to cut and it will hurt your whole body doing it. You then need to vacuum the dust out of the holes, mix the compound and fill the holes. Ecobust recommends that the holes are spaced no more than 8″ apart and that you drill a hole that’s 80% to 90% of the depth of the rock. You also need to excavate around the boulder so the fragments can be pushed outwards or it won’t work. I’d also excavate underneath until you see the boulder’s bottom starts to emerge, you need to know how deep the boulder is and if it’s sitting unevenly. If you drill all the way through you’ve wasted a hole — all that pain for no gain.
You also need to think about your fragment size when you’re working out your drilling pattern. There’s no point in splitting a 500kg boulder into two and then trying to work out how to lift two 250kg pieces. I’d recommend putting more holes into the boulder.
The mixture looks innocent and may take up to three days to work but it will work. I’ve split three rocks using this method and it works every time. Ecobust cost me $40 for a 5kg bag which was just enough for my 9′ of holes (six holes, ~18″ deep and 1½” in diameter). It cost another $60 to rent the drill and bit for 4 hours so all told it was only $100 to deal with a boulder that probably weighed close to 500kg (1,100 pounds).
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