Dave, you didn't say there was any upper limit to the size of one post, so I thoguht I would give it a workout.
Here is the "before" - even weeds had a hard time. Like, were weren't any. Just rocks and clay. Note the slope,
Then, I invented mud. Water may run downhill, but once it meets pure clay, it stops running. <1 - 2 - 3>
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I trenched deeply, actually UNDER the lowest bed, where the mud puddle is now.
Then I ran a long trench the length of my driveway to drain down and away from there.
This lower bed drains the upper beds SOMEWHAT, and I sloped the floor of the upper beds down towards it. <4.5.6>
I ran a trench the length of my driveway to drain the mud puddle. <7-8-9>
I like the idea of "filter cloth", whether it is really needed or not. <10-11-12>
For a big trench, the 3" pierced, corrugated drainage pipe is great.
It's infintly cheaper and lighter than an equal volume of drainage gravel. <13-14-15>
Putting things back together, the drainage pipe runs UNDER the lowest bed, with more cobblestones and gravel, between it and the driveway.
In the next three shots, the camera pulls back and pans left until you can see the upper bed and the remaining juniper patch to the left. <16-17-18>
This allowed the clay to drain (or run off) even in our constant and sometimes heavy rain.
I removed a lot of clay and rocks, amended, bought two yards of topsoil, amended again, and turned deeply.
Now it drained well enough despite always needing more compost, and roots could go deep.
Now things will grow there, and NOT just weeds! <19-20-21> <22-23-24>
Much later, I removed more juniper bushes and extended another deep trench farther up, almost parallel to the driveway, downslope from and deeper the floor of the UPPER bed, draining it directly.
I laid gravel and paving stones on top of that as a sunken sidewalk. Now I don't have to bend over much to reach that upper bed. This wall is 16" high, being made of 8"x16" pavers stood the tall way. (Some day I plan to make a little half-height terrace here near where Toby-the-Cat sits, narrowing the walkway, widening the upper bed, and making it into two 8" levels).
The upper and lower trenches almost connect, but a little work remains to be done to connect them completely, before I turn the left-hand patch of juniper into yet another bed.
And the last shot is the low point, "Before Trenching" . <25-26-27>
