I was looking at information about how to dig trenches as I am planning to put a shed in the backyard with electric for a workshop. The distance is about 30ft long and about 20' deep as the electric cable was buried in PVC at 18' deep. I also wanted to install a separate PVC conduit for internet cable in the same trench. The path ran close to a dry well so I didn't want to risk damage from a machine, and I wanted to try to save the sod to place back on the trench.
One of the tools recommended from my research that I wanted to try was a grub hoe, but that style of hoe is difficult to find at your local big box stores. I found this website recommended from a couple articles and forums I read and they had solid looking tools. I decided to buy a grub hoe, a sharpshooter shovel, and a trenching shovel.
I bribed my brother-in-law to help with the digging. We first started by using left over 12ft house siding strips to plan the path and mark an outline 10' wide in spray paint. The I put out a tarp and used a lawn edger to cut 10'x10' square sod pieces and used a shovel to pry and dig them up and lay them down at the back of the tarp. This got us down about 4'.
Next, we planned to dig in three passes of 5-6' depth increments. The sharpshooter shovel was the best tool as at the early depths as it appeared to penetrate the soil which at this point was mostly clay. We rotated between the grub hoe and regular shovel to pull dirt out of the trench and onto the tarp as we dug deeper, then used the sharpshooter to penetrate or shave off dirt at the edge of the existing trench. We'd use the sharpshooter as we went to square the trench instead of a 'V' shape.
Since the path ran close to the dry well, I ended up slightly puncturing a pea gravel spot that was wrapped in landscape fabric. I had to pry the corner of the pea gravel 'pillow' and dig underneath it. The sharpshooter came in handy to slowly chip away at the dirt underneath without damaging the 'pillow'. There was also a 4' PVC drainage pipe that I suspected but wound up in an unexpected path, so hand digging saved us from having to repair that.
However, things significantly got harder at a depth of about 16'. To get to 20' deep, the final 4' was very compacted clay with rocks and gravel. At this point, using a regular or sharpshooter shovel on this soil only produced very small chips, and that's with a lot of force. The best tool at this point was the grub hoe as we could get a wind up and let gravity do the work to help chip the dirt away. The rocks made it a bit difficult as the grub hoe blade wouldn't make progress if there were rocks in the path.
In hindsight, a pickaxe might have been better, but I felt the grub hoe still worked well enough to not run to the big box store to buy a pickaxe. We used the grub hoe to chip the spoil, then use the sharpshooter and regular shovels to remove the soil at this depth.
When we got to 20', we used the trenching shovel to help dig out a flat bottom for the conduit. We had to measure 18' from the top of trench at ground level to the top of the PVC. Once that was completed, we did a victory pose on the large mound of dirt we excavated.
The next problem was that next to the house, there was a concrete lip at about 16-18' deep that prevented the PVC sweep from being flush against the house and getting to a depth of 18' at the bottom of the trench. At this point, I got a 4lb sledge and chisel and we took turns chipping a path in the concrete so that the bottom of both PVC sweeps exited at 20' deep.
It took some time, but we finally got the PVC conduit dry fitted, then glued together. Next we started the backfill, and to provide for inspection, we cut two 4ft PVC pipes to place 6ft from each end of the conduit for depth measurements. I had bought a 8x8' tamper so that we could try to keep those in place and reduce settling of the dirt in the trench. We tamped as we went for every 4-6'.
Once we got near the top, I soaked the trench with water to try to get any soil to settle (especially under the pea gravel 'pillow'). After doing that a couple of times, I placed the sod pieces I cut back on top of the trench. I had to shave off the bottoms with a potting trowel with a serrated edge of the sod pieces because the bottoms were uneven from prying up the grass root mass. I raised sod an inch or so expecting more settling, but the hand tamping we did seemed to avoid any noticeable settling.
Finally, I took topsoil and grass seed to try to fill the gaps between the sod squares. There was a pile of leftover dirt that I kept on a tarp (which I used later to raise the grade of my dry well, which had settled some 2-3' over roughly a 4x4' square, which is a different story).
Time wise, the two of us spent 9 hours Saturday digging the trench, 6 hours on Sunday chipping concrete, laying and gluing PVC conduit, then partially backfilling about 12', the. Monday about 6 hours finishing the backfill and sod replacement. The MVP was the grub hoe for the heavy duty work at the super hard soil, though the sharpshooter pulled its weight in gold as well.
Overall the tools held up to a lot of abuse and I'm thrilled with the purchase. If your digging a trench, both the grub hoe and sharpshooter shovel are a must! Hope this is helpful.