Saturday, August 12, 2017

Heavy Lifting - Raising a Large Landscape Rock

I wish I had thought of taking before and during pictures, you will just have to use your imagination as I describe the project my husband and I tackled this morning. The pictures in this post were taken later in the evening after it rained.

We have a large landscape rock in a garden bed at the intersection of our driveway and sidewalk. We had built a bit of a mound before we had the rock yard deliver and place the rock in the garden because of the slope down from the concrete. Sometime after the rock was placed, we used a similar technique as we did today to add a little more fill under it. Possibly in part from the fill settling or just because the garden wall we had built would cause the base of the bed to be higher, I figured out last week that the rock would need to be raised another 3 - 4 inches, in place preferably because I liked its location and orientation. Did I mention it was a big rock?

This was much more than a "Honey would you move the couch over a couple of inches?" request but my husband was game to help me. I had a plan and set out to get everything in place. My car would need to be the anchor for the come along and a nylon strap ratchet wrapped around the rock. I strategically placed the car in the yard and attached the come along to my trailer hitch bumper. I then wrapped the nylon strap around the rock twice and adjusted it so that both hooks would bear the same tension when attached to the other end of the come along. Now it was time to see if I had lined everything up correctly so that the base of the rock nearest the sidewalk would lift instead of the rock being dragged forward. Hopefully when lifted the rock would be stable enough for my husband to add some encouragement if the rock tried to rotate or tip to the side. I cranked on the come along, the attachments tightened and a very small indication of movement appeared. We paused. The rock was still stable. We got out the large pry bars to help ensure that the far side of the base would lift instead of having the whole rock slide forward. With my husband on the pry bar and myself on the come along we achieved the movement we wanted. After lifting the end of the rock up a bit higher than I would eventually need it, I placed and packed a mixture of paver sand and decomposed granite under the raised base of the rock. Thankfully I had managed to nail the direction of forces through the center of mass so that the rock was very stable and no encouragement was needed to keep it from tilting side to side under tension. After packing the material for the raised pad we released the tension on the come along and still had a stable rock. So far so good.

Now we had to move the car onto the driveway and repeat the process from the other side. Luckily the pack job was sufficient that when we winched up the opposite end of the base of the rock, the closest end of the base did not dig in and crush the newly created mound. I did not nail the center of mass and force application quite as perfectly as the first time but it was good enough that my husband was able to apply enough encouragement to keep it from rotating around a vertical axis like it started to. Once I packed more material under the raised end, the rock became stable under tension and still was when we released it.

Physics is fabulous. By using a few simple machines to help us multiply our force several times we were able to safely accomplish our goal of lifting our very large rock in place by 3 - 4 inches so we could install more fill to maintain it at that height. After completing this part of the task I spread chips to level out the surface of the garden bed around the rock.

What led me to wanting to raise my rock? Earlier this week I realized that my silver ironweed I had planted near the newly reset Pavestone wall would need to be raised because I needed to add a full paver height of mulch on that side of the garden and that would be too much for this drought tolerant plant. (It is the gray plant to the left in the second picture and the right in the third one in this post. Click on the images to enlarge.) After lifting my plant I realized I should raise the current edge of my planting bed next to the walkway on the black plastic (second picture) so that the chips were level from the Pavestone wall to the driveway. It became apparent that I would have to bury part of the rock in chips if I leveled out the rest of the bed in that location so the rock had to be raised.

I am so glad that we tackled this portion of the project this morning. With the rain we received today I would not have been able to drive my car through the yard and the bed would probably have been too wet as well. I still have four or five plants seen in the last photo that I will need to lift up before adding more chips. However, that will wait until late fall or winter because those plants have been in place longer than the silver ironweed had been. Transplanting will be easier on the plants in cooler weather.

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