Garden Wall for 4180 sw 99th

http://wiki.keithl.com/GardenWall rev 0.1 2022 Aug 11

Our neighbor's new fence is already in place, we will not be building that on top of the wall, but build the wall beside it, hopefully with the top cap extending near it ... somehow.

Answer zero: Wall color: Summit-blend split-face color, so dirt shows less. Most of the wall will be facing the fence, with a top cap, so only the wall that sticks up above garden level will be visible.

Q1: With the wall beside the fence, there will be a "triangular void" that we don't want to fall unto. Perhaps we extend the wall cap to abut that. What can go wrong with that (insect nests? fence rot?), and how do we prevent problems:

There are non-treated boards below the level we had asked for, so I faced those with some hardi-plank and leveled the dirt to them, so that our walking path is level. That will bring the west end of the block wall eastwards a few feet, but won't change the volume of the wall or the scope of the work very much.

There are some large rocks in the ground left over from the previous railroad-tie wall. Those are very heavy and require machine removal. Otto, not Manuel. I don't want those heavy, nonstructural rocks causing mayhem in an earthquake.

Q2: How much can you lift with the digging machine scoop? Will we need another machine or tool or winch for that?

Digging beside the fence and placing a wall will require a trench as wide as the digging machine scoop.

Q3) How wide is the scoop?

Q4) How wide are the tracks of the digging machine beside the scoop?

We will need a stable track (how wide?) for the digging machine, which overlaps where our garden currently is. We plan to replant the garden anyway, so track away! We can temporarily screw some plywood on our side of the new fence so the machine won't damage it.

A wider wall unit with a hollow center, like the CornerStone 100 flat face block, will be more stable in an earthquake ( read Living with Earthquakes in the Pacific Northwest to learn how lethal they can be in western Oregon ). The Near Vertical Flat Face 100 Unit will make the gap to the fence smaller, but is more likely to tip with a fast ground displacement.

I much prefer stable and earthquake resistant to a few more inches of garden space.

I propose we extend the wall 12 inches above the dirt. A 4 inch high "Flat Face 50 Straight Side Cap" on top of that wall, raising it to 16 inches. And on top of that, I can create a sitting bench of composite deck planking, filling in the gap to the fence so that nothing falls down there. That will create a 17 inch high bench for sitting, planters, or tools.

Except ... wasp nests? we probably don't want to leave big hollows. Unsolved problem. Perhaps we fill the gap to the neighbor's wooden fence with packing peanuts and bubble wrap from Too Many Amazon packages. I hope you have a better idea.

The flat face block units are 18 inches wide and 8 inches tall (one square foot), so as a wild guess 120 blocks (40 units on 3 pallets) and 25 caps, including breakage and goofs.

To strengthen the wall further, some 4x4 composite lumber poles in the 5 inch holes that thread through and between the interlocking blocks. I considered raising some of those poles up above head height, and hanging planters on crosswires, but that will cause a lot of side torque in an earthquake. Better to use separate posts planted in our garden soil, not the wall.

Possible Change of Plans: Steps on the East Side of the East Garden Wall

Accessing the back of the (past and future) greenhouse requires walking all the way around the east end. If we build steps downwards from the east side garden wall, we can access that faster. What is the best way to do that?

I hope the garden soil can drain through the bottom tier on the short eastern side of the wall ... somehow. Perhaps extending farther to the east, beyond the current "face", and filled with large crushed rock. If trench is wider than 18 inches, we can lay a perforated plastic pipe (with a permeable sleeve) as a french drain, next to the bottom tier of blocks.

Note: I manually dug french drains near the road and driveway, and in the back of the house (and got a hernia injury doing so, never again). I don't want you folks getting hernias either (though I can suggest a surgeon).

French drain gravel from Cedar Mill Landscape Supply, they deliver by the truckload. We may also want to gravel our south side grass driveway, so you and other contractors don't sink in that bog.

More added here later, if you have questions or I think of something else.