Photo sharing. Most of the older sites we have used over the years have begun shutting off 'third party' photo sharing. I just got a message from Photobucket that 'third party' sharing will quickly end unless I spend more money to keep that feature. Not so willing to pay the added fees.
Tom Trigg
Eric
Ground subsidence will be an issue for several more years. You say you have about 2 inches of subsidence in 2 1/2 years. In another 2~3 years you should expect another inch to 1 1/2 inch more subsidence, and so on over the next dozen or so years. Be prepared to repeat whatever you do this season in a few more years. The quick fix would be to get a 5 gallon bucket of crusher fines. Pile up a bunch between the rails followed by vertically shaking the track allowing the fines to settle under the ties. Repeat as needed to raise the track to the desired level. Add this task to your yearly late spring time to do list. I say late spring due to my experience, most of my subsidence (yes, I still fight subsidence after 17+ years) occurs during winter/ early spring.
You also stated you want to experiment and develop more skills, while keeping the uneven natural low areas for the visual effect. A 48 inch long, 2~3 inch tall bridge will be a great visual enhancement. If you go with a timber trestle bridge be prepared for annual maintenance. As the ground under the bridge continues to subside some posts will lift out of the ground while others will drop along with the soil. A through truss bridge set atop concrete piers might be a better choice, but MUCH more work. Build a wooden form to make a series of identical piers that reach down 5~6 inches below current ground level. You could experiment with making a rubber mold to make the piers. These piers would need to be supported by a structure that reaches down to at least 3~5 inches below the original grass level from before you built the GRR. Just a couple of possible support methods; (1) Get some red bricks and split them in half and dry stack them from below grass level to a point 4~5 inches below current ground level place your piers atop the stack. (2) Get some ABS pipe (black PVC), dig them in below the grass level, fill with mortar mix and top with the piers. In either case as your fill continues to subside the ground level will slip down the side of your piers doing away with any need to backfill under the bridge. I would recommend not using any backer board as it will it will expose itself as the subsidence continues over the years. Unless you could find a way to anchor the board to your retaining walls.
My experience with major subsidence is in an area where the track crosses a rose bed, a 30 inch wide, 36 inch deep trench filled with compost. The compost fill went in during the summer of 1995 and still continues to subside. My solution was to dig down and place a cedar 2x4 spanning the gap plus a foot on each side of the trench into the clay, original 'soil' my house is built upon. I set a timber trestle bridge atop the 2x4 to support the rails and backfilled with more compost. I am at a point where I can no longer backfill with more compost as it would bury the the main branches unless I dig and lift up the rose bushes, way more work than I'm willing to do.
I'm interested to hear how you solve your issue.
OK,
Efforts to use OneDrive to post a photo to give a sense of the project opened a pathway to my entire family photo album (fascinating, I am sure, but a bit beyond the subject matter!), so I am going to have to try and describe this project with words.
The garden settled about 2" along a 48" length of track that more or less abutts the garden's retaining wall. The finished project will thus only be visible from one side and, of course, from the top.
From a practical standpoint, I just need to get the rails level. From a visual standpoint, I want to take advantage of, rather than fight, some of the undulations in elevation from settling over the last 2 1/2 years. I want it to be solid enough to allow for adjustments as things continue to shift about, and I want to use the project as an excuse to dicker with some other tools and techniques.
My thought was to use a hardiebacker sub-roadbed (snapped to size using a score-and-snap technique I recently learned about) mounted on some sort of core. I had thought about foam, sealed behind latex paint, for the core which would keep the weight down and make it easier to adjust as required. I would then glue foam to the side and score witha hot knife for texture. I can also use something more substantive like bricks for the core if this would be better. Thoughts?
I am also mulling scrapping the whole retaining wall idea and, instead, building a bridge and leveling out the garden bed underneath. This would be something simple, using some techniques Tom shared in another one of my posts. It would accomplish the same thing, I think, but I am not sure how it would look.
As ever, I would appreciate any "guidance to the helm!"
Aloha,
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