Just finished installing and calibrating the flow sensor in an underground installation.
Go with the folding jab saw with replaceable Sawzall blades and use a fine tooth blade. I used the fixed jab saw as it had a thicker blade and more aggressive teeth as I wasn’t sure about the sawing down into the dirt. Ended up with a few jagged edges. The aggressive teeth were nice for cutting on the valve box, though.
Buy the Orbit PVC-Lock release kit with the bevel tool. I used the bevel tool to smooth off the jagged edges from the cut. I also used the release to move one end of the of the fittings to where everything was touching before I screwed together the Orbit manifold fittings as there was a little gap in there as they PVC-Lock fittings will slide more than an inch in (I believe). This way there was no pulling stress on the components when they were all connected together.
I dug out the hole enough for the new valve box before I cut the pipe. This way there was no more shoveling/digging when the flow meter was installed.
I have one zone that is downhill from the flow meter installation location. I started that zone and then shut off the water to the sprinkler system so most of the water would run out of the pipe and not back into the hole when the pipe was cut - there was some, but it was minor. So run the zone that is lowest in relation to the flow meter installation location.
No matter where you think the field wire is, it will end up under the point of the shovel before you know it. Only a couple of nicks and double wrapping of electrical tape took care of that.
If you’re a pre-planner and doing everything at once, allow 30 minutes after the Gen 3 is installed before trying to pair the flow meter - this appears to be an undocumented feature.
Pictures: (as @Franz says it didn’t happen if there aren’t pictures.)
The hole. The Rachio controller is probably 6 feet on the other side of the white wall in the background, so not a good test for maximum range