Am I crazy or is my best option to terrace? Maybe both?

[throwaway]

My current garden is ~15'x10' at the sunny end and 15'x6' at the shaded end. The wide half gets ~5 hours of sun and the narrow half ~3. This garden is on a relatively flat section at the crest of a hill behind the house. I think the canopy has grown and reduced my sun hours over the few years I've lived here. Squash do not produce, cucumbers do so/so. I believe my tomatoes would probably do better with more hours of sun.

There are some railroad tie steps leading up the hill next to the garden, and then 40' of ~8'-10' tall x 12' deep ~36 degree slope, that is just covered in wood chips and weeds. Unusable as is, barely navigable on foot. Serves no purpose, other than a short wall of railroad ties and a perforated PVC pipe to drain water away from the house. I figure I could spend the next 40 years using a string trimmer to clear the weeds or terrace the space into planter beds. That area seems to get ~6-7 hours of sun.

I figure 3 levels of beds, 4' wide each with a 1.5' walking path, gives me 300 sq ft of additional garden space with some of the best sun on the property. Worst case scenario I could convert it to ornamental bushes and flowers if I need to sell the house at some point. Best case scenario I can do a better job attracting pollinators and produce better outcomes for tomato, squash, and leave room for berries.

Thoughts? Can it be done aesthetically? Do I need an engineer?

[bower]

Definitely terrace! No matter what you do with it, it's going to add value to your place.
As for design, if you can take a pic and make it digital, you can try out the basic design possibilities on paper to see what pleases you the most aesthetically. To my mind, terraces are intrinsically aesthetically pleasing.



Re: engineer and safety. You have to make sure you retain the drainage that is necessary to protect your home. Can you do the terraces without disrupting the existing drain?

I can only think that terracing an area of sloping, weedy/mulchy land would improve the structure for water retention. If you use some perennials it will help too (berries?). If there is any concern about runoff in extreme conditions, you could build additional drainage at the farthest edge of the slope to make sure excess water is directed away from your home. And maybe that would also protect the terrace structure from any risk of collapsing in flooding conditions?

What kind of material will you use for the retaining wall of the terrace, and how high would that be?



How high is the present garden crest area compared with your home? (how many ft higher)
Is 40 ft the distance from your home to the back garden?... I am not good at visualizing without a pic. I think it's an exciting project!

[throwaway]

Thanks for the response, will try to snap a pic this afternoon (or at least diagram, but my artistic skill is...there is a reason I garden :p).

Garden crest area is also ~8' above home level, although it slopes downward modestly toward the house before the steeper cut. The 40' distance is parallel to the house (50' if I wrap around the side).

Material is a great question! I am paranoid about leaching from pressure treated wood - and I try to plant a healthy distance from the railroad ties. So I guess stone for the retaining wall. Back of the envelope puts me in $2-3k for stone though.

The property is built really well with regards to drainage. I don't think the terracing would impact the current drainage, provided I don't destabilize the hill! I believe there is a perforated PVC pipe that runs down the slope around the 25-30' point on the hill looking left to right, which is my only concern with this plan. Wondering if the town might have diagrams or permits that explain how this whole system works.

I'm with you on the perennials. Raspberries, blackberries, honeyberries, shooting for the moon ^_^.

[bower]

I have a little terraced area in my yard that I've been working on for a couple of years in a haphazard way - no worries about collapse since it is above a natural drain and not above my house...



So I looked up drainage for terracing and apparently the professional way is to build drainage at the foot of each retaining wall. That is (or especially!) if the rise is more than 2 ft. They also recommend you hire a professional if it's a higher rise than 2 ft.



https://www.nrcs.usda.gov/wps/portal...nrcs143_023575
says the pressure of waterlogged soil behind a retaining wall can cause it to collapse
https://homeguides.sfgate.com/things...ard-58108.html
gives some detail about methods:
"Any terraces using walls that are more than 2 feet tall usually need a landscape engineer to determine wall strength and soil weight calculations. These terraces cannot have a basic wall and soil configuration. For example,landscape fabric holding gravel for water drainage is necessary at each terrace's base; the topsoil resides above this configuration. Along with adding a drainpipe to the fabric and gravel arrangement, the wall itself needs to be tilted inward by 1 inch at every 1 foot height to remain upright against the heavy soil and in case of an earthquake."


36 degrees is fairly steep, just guesstimating you would have a rise of 3 ft for a run of four? ish.
If not up for hiring a pro, maybe there is some way to adjust the design so your rises are lower...? but would probably compromise the plan to use all of the space.



One important thing that was mentioned, is to check with utilities companies first and make sure no pipes or cables are buried where you want to dig. That would be a bummer.

https://homeguides.sfgate.com/build-...ard-60649.html


I really sympathize about the encroaching canopy issue, which is a problem I share in a big way. There are big trees that really need to be cut as they are not only shading my greenhouse but are menacing the house in high winds as well. I went around the other side of my garden with a pair of loppers this spring, and I was amazed how much sunshine was restored to the back of the garden just by cutting the lowest branches, which had extended out over the garden beds. No such luck with trees by the house, though.

[throwaway]

I think the town code calls for a permit at 4', so I suppose 3' could technically be done without "help". Probably safer to bite the bullet and pay a professional, at least for the design. Tried to upload images but forum software puked.

Biggest issue today is the running bamboo previous owner was kind enough to plant on the hill (think the far side of the 50' run, away from garden). Alternating between mowing down new growth and ripping rhizomes out of the ground with hands, shovel, blade, whatever else. Hope I'm winning a war of attrition, but I've already dumped a retaining walls worth of funds into removal. Plus I figure as the rhizomes come out, the hill loses some strength. Then again, the hillside planter idea is motivation to finish this process!

The trees make the bamboo removal that much worse as the roots are tangled with the rhizomes, and I worry that cutting through the wrong roots could kill the tree and necessitate profe$$ional removal.

[SueCT]

Might be worth it if its an option to get a professional so they can get rid of the bamboo, too. They have heavier equipment to dig that stuff up. I am sure they would not go at it with blades and shovels like you have.

[bower]

Well it was too windy for me to garden today so I ended up on google looking everything about terrace construction. I love looking at the pictures, but also found a couple of good references that describe the engineering of terraces pretty thoroughly, so if numbers and calcs are your thing, you may enjoy these:
http://www.soilmanagementindia.com/s...nagement/15303
https://nrmdblog.files.wordpress.com...ace-manual.pdf


In the second one, there's a table of diagrams on page 3 showing different terrace design types, which I especially liked.

Also they both quote different formulas/designs depending on soil type, precipitation and other variables, which means you can figure out what applies to your situation especially. If the town bylaw allows terraces up to 3 ft rise without a permit, it is probably one of the more stable soil types. At least if you're consulting an engineer, it's worth knowing how they think about it upfront.



These references mostly talk about slopes of 30 degrees or less, but obviously there's a great variety of historical designs on steeper areas, and not all of them have a really high rise for the retaining wall. See for example this diagram of modified terrace with interval slope. The retaining rise is short while the extra elevation is gained in the interval - somewhere you could plant lots of berries I reckon! and easy to harvest from below. So there is more than one option that could work with steep slope, without a very high rise.
More small steps is another way to approach it - you could make your walkway a step above for picking tomatoes (I know I would like that instead of getting on a ladder to mess with them). etc.etc...!!!

[bower]

Actually just re-reading your description which is starting to make sense without a pic, you said it is 12 ft deep and 8-10 ft high, that doesn't sound dangerously high to me even if there is more mountain behind it, and the three terrace plan should do it perfectly.
Don't know what to say about bamboo. Worse than goutweed I heard. I haven't handled it myself.


I'm sure you've read it all - I liked this article because it says don't tarp without underground barrier - that makes a lot of sense. Same with the gw and other spreaders....

https://www.thespruce.com/how-to-get...urally-2132939

[Worth1]

You can save a ton by making a homemade A Frame to run the terraces.
Simply put one leg after the other rotating and walk the thing around a slope.
I built one years ago to do some work on a hill.

[throwaway]

Originally Posted by SueCT

Might be worth it if its an option to get a professional so they can get rid of the bamboo, too. They have heavier equipment to dig that stuff up. I am sure they would not go at it with blades and shovels like you have.

It is a fair point, but the bamboo removal by heavy equipment would definitely require removing 6-8 large trees and come too close for comfort to the natural gas, water, and sewer lines. I figure that sets me back at least another $5,000 provided they don't break anything. Retaining walls are at least another $3k worth of materials, equipment and labor I figure $6-$10k. $20k doesn't sound terrible if I imagine amortizing the cost over the mortgage.


Looks like I have a bit to read up on today.