Dry Rock Retaining Wall

I live in Maine at the top of a hill along the Kennebec River... The lawn on the south side of the house slopes gently toward the river, and abruptly terminates where the driveway goes up to the house... This poor lawn is in the shade 95% of the time, is poor soil (including diggings from a project that was done prior to my buying the house), and as a result doesn't have much grass and an overabundance of moss... There is a quaint brick walk that runs from the front door to concrete steps down to the drive (the steps are in the middle of the drive)... In recent years (I inherited all the previously cited items) there has been some erosion in the soil next to the driveway, particularly where the walk meets the steps (with the loss of three or four courses of brick)... Other than this runoff, which has occurred on the sharp slope from the lawn to the drive, the soil is quite stable....
My wife, bless her heart, had decided she could no longer live with the mossy walkway, and dug it up in order to restore it... I had wanted to consider this particular project for a bit longer (about 10-20 years or so), but now I'm kinda forced into action...
I want to build a dry retaining wall of field stone around the top of the steps, then taper the wall along the drive in either direction... I have an OLD rock wall in the pasture behind the house that marked a former boundary line (the line has since moved, now marked by a row of trees)... I plan to use the stone from this wall in this project... After the wall is in place, I can put good soil on the lawn and reseed with the appropriate grass.... These steps are about four feet high at the top, this four foot height the wall will need will taper to about three feet high at the street, and taper to nothing as you come up the drive to the garage...
I've done plumbing, carpentry, roofing, flooring, and concrete projects... I have never done anything with rock, so I have a bunch of doubts in my head and would like to save as much of my back as possible.... I know I need a batter of 2 inches per foot of height, I plan to put about eight inches of crushed rock in a trench at the base of the wall, I expect the wall to be about 24 inches wide, made of field stone... I plan to backfill the wall with topsoil to the level of the lawn....
Since this is dry, with no mortar, I don't expect to put any drainage pipes into the wall...
If anyone has any experience with such a project, and would care to inform me of the evil unknowns I'm about to encounter, I'd certainly appreciate any comments and advice....
I'll post pictures as this project progresses... I'd like to be done before the snow flies....
Bob Curry
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Is there a question in here?
Retaining walls in municipalities often require an engineer's stamp Here it is required at 4 feet.
Manufactured "Garden wall " blocks are not recommended above 2 feet.
Manufactured block similar to Keystone block are about 70 - 80 # each with some system designed to interlock the blocks.
Concrete walls are designed to resist roll over by brute strength provided by the footing or mass. It would still be normal to provide drainage at the bottom of the wall to reduce the hydrostatic pressure
Manufactured walls are designed to leak. It would still be normal to provide gravel drainage behind and under the wall to reduce hydrostatic pressure.
Your dry stack stone wall will need to meet the same requirements. The stones will need to be quite large, interlocked, and well drained with sufficient mass to resist the pressure of the dirt in a semi-liquid state during rainy weather.
I hope this helped.
Keep the whole world singing. . . Dan G
(remove the 7)

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I think there was.

He's in Maine. There are no municipalities up there, just territory signs with numbers :-)

He's using stone from an old wall.

OK, back on track.
The well draining part will come from all the holes left from these somewhat rounded stones he will probably be using. Raw mass and interlocking" are the issues I'd worry about. On the raw mass side, the farmers who built these walls used horses, wagons, and neighbors to move them around. Unless your wall is different than most NE walls, some of those stones will be way more effort that they are worth. Try moving some of the large ones and see if you think you want to move the whole wall. You might be better off just buying stone and having it dumped where you plan to build.
The second problem is the interlocking... it is relatively hard to get these rounded NE wall stones to lock together and become solid. Flat, sharp broken stone is a whole lot easier to build with. Again, buying pallets of stone might make this a much better project. There's a reason that most of those dry wall are not over 2-3 feet tall.
If I'm wrong about the type of stone in your wall and it's all small flat stone, ignore everything I said above.
Some guys use landscape fabric and gravel behind the wall to aid drainage through the wall and avoid pressure behind in the rain. Some cheat and use mortar in back to hold everything together while leaving the exposed side looking like loose stone. That might be good on the sections over 2 feet high. That is, mortar the bottom couple feet of the tall sections so that the loose sections are never more than a two foot stack.
Bob
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