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Equipment on steep slope: that first cut for swale

Posts: 17

Location: 10 Miles ESE Walla Walla WA 46°N 118.11°W (Elev. 2195 ft)

posted 1 month ago

My upper slope averages 25 degrees, a little over 50 percent slope. I am considering both swales and keyline development. The prospect of sidehilling equipment is terrifying.

I'd appreciate any advice from real experience in getting started.

Here is my thought at the moment: Dozer with tilt blade goes straight up to the contour point of start. Push and drag enough to get a flat enough landing to turn 90 degrees. Tilt the blade to start a cut for a pioneer lane, leveling the blade as soon as the dozer is fully on the cut. Push ahead, sidecasting to the downhill side. Before extracting the dozer, run fwd/back to compact the downhill sidecast enough that a track excavator is stable, but no so much that the material becomes impermeable. (Right, sure...)

Phase two is run an excavator up to one end of the pioneer lane and excavate the trench. Getting the proper slope on the trench sides is where I am "stumped."

5 Acres 25 degree west facing slope, conifer dominant on rocky silt/loam over basalt.

Douglas Alpenstock

pollinator

Posts: 589

Location: Canadian Prairies - Zone 3b

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posted 1 month ago

I hear you: working on slopes can be extremely hazardous. Stay safe. Your soil type, moisture content, and its tendency to slump are big factors.

How long and wide are your proposed sidehill cuts? It sounds like you are planning a large-scale earthmoving project.

Personally, I would be tempted to have a pro do the initial work, because they know their equipment so well.

Randal Son

Posts: 17

Location: 10 Miles ESE Walla Walla WA 46°N 118.11°W (Elev. 2195 ft)

posted 1 month ago

Thanks. My soil is high percentage clay, covered with several inches of duff. Slicker than shit when wet.

I am still working on scale and scope. If swales are feasible on this ground, I am thinking 4 or 5, 2 feet +/- deep, 2 feet across the bottom, 300+ feet long each.

I have long way to go to decide if swales are feasible. In any case I need a first walking/ATV lane across the slope.

5 Acres 25 degree west facing slope, conifer dominant on rocky silt/loam over basalt.

Ben Zumeta

pollinator

Posts: 689

Location: NW California, 1500-1800ft,

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posted 1 month ago

I am pretty sure swales are not advised on slopes above 15deg, and are especially precarious with clay soil as when saturated it is prone to slides. Permanent tree cover, ideally with species that have leaves present to slow and spread rainwater during the rainy season (meaning evergreens in the Pacific NW I’m in) is the best watershed management practice according to many sources I’ve read (Mollison, Fukuoka, Loess Plateau Restoration protocols, NRCS). This is also what nature does when left to its own evolution. At least tree planting is less work and safer than making swales, but probably not what you want to hear. It’d be good to plant before your rainy season and choose varieties that need no irrigation.

This is all just my opinion based on a flawed memory

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Douglas Alpenstock

pollinator

Posts: 589

Location: Canadian Prairies - Zone 3b

140

posted 1 month ago

For the first trail, consider using a walk-behind rototiller to chew up and level a trail. I've done it and it works quite well. Your shoulders will know it the next day though.

Randal Son

Posts: 17

Location: 10 Miles ESE Walla Walla WA 46°N 118.11°W (Elev. 2195 ft)

posted 1 month ago

Thanks. I had not seen the 15 degree limit anywhere yet. Very useful. The rototiller idea is also a good one.

5 Acres 25 degree west facing slope, conifer dominant on rocky silt/loam over basalt.

Rene Nijstad

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Posts: 298

Location: La Mesa, Cundinamarca, Colombia

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posted 1 month ago

We have some relatively steep slopes and we've terraced the areas we want to use, with an excavator. We dig a small road first that goes up or down the slope, and from that road we go sideways. When making terraces make sure that the downslope side is made higher than the upslope side, so that excess rainwater does not flow over the edge but towards the mountain side. Also make sure that there is an overflow somewhere so that excess water can drain of. Without that overflow you risk landslides in heavy rains (unless you're willing to build retaining walls to hold everything in place).

https://www.wetdrytropics.org

R Scott

pollinator

Posts: 3600

Location: Kansas Zone 6a

posted 1 month ago

I have similar and some worse (over 100% slope). I have talked to Mark Shepard about this. He has personally built "swales" on what he called a cliff. Stacked rocks on keylines to turn a ravine into a garden in Kenya. BUT you have to be extremely careful to keep the water holding small enough to not risk landslide. I think anything over 15 should be left to professionals.

I am not going to tackle that on my place, I am going to drop trees that need to be thinned on contour and start piling debris to form silt traps and hugel ish structures

The walking tractor and rotary plow make a good start for foot paths. Not all the engine choices can handle that kind of slope!

"You must be the change you want to see in the world." "First they ignore you, then they laugh at you, then they fight you, then you win." --Mahatma Gandhi
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R Scott

pollinator

Posts: 3600

Location: Kansas Zone 6a

posted 1 month ago

But if you want one machine that can do it all, look up the menzi muck on YouTube!

Douglas Alpenstock

pollinator

Posts: 589

Location: Canadian Prairies - Zone 3b

140

posted 1 month ago

R Scott wrote:The walking tractor and rotary plow make a good start for foot paths. Not all the engine choices can handle that kind of slope!

That's true. Engines that use dip-and-splash lubrication can't operate at a large angle, unlike oil pump lubricated ones. I use a dipper, but basically I make an initial flat shelf and then extend it, cutting into the hill as I go along. Grunt labour, but sometimes you use what you've got.

Randal Son

Posts: 17

Location: 10 Miles ESE Walla Walla WA 46°N 118.11°W (Elev. 2195 ft)

posted 1 month ago

Thanks again, good food for thought.

I should say my long term objective is to facilitate a food forest. Fire prevention, safe water retention and building soil fertility come first. I probably won't live long enough to see it really flourish, but if I start, hopefully a successor will stick with it.

Woah! that Menzi is beautiful!

5 Acres 25 degree west facing slope, conifer dominant on rocky silt/loam over basalt.

Douglas Alpenstock

pollinator

Posts: 589

Location: Canadian Prairies - Zone 3b

140

posted 1 month ago

"A man only begins to grasp the true meaning of life when he plants a tree under whose shade he knows he will never sit."
- Ancient Proverb (one of many variations)

Eliot Mason

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Posts: 263

Location: Beavercreek, OR

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posted 1 month ago

One degree-of-separation from actual experience ... a spider or walking excavator (such as the aforementioned Menzi Muck) is a tremendous machine on steep slopes. Not very common but a thing to keep in mind when planning what's next.

John C Daley

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Location: Bendigo , Australia

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posted 1 month ago

This web site details in the images when not to use swales.
It mentions not doing it on land with greater than 15 degree slopes and provides references as well.
when not to swale!

John Daley Bendigo, Australia
The Enemy of progress is the hope of a perfect plan

Benefits of rainfall collection https://permies.com/t/88043/benefits-rainfall-collection

Alex Arn

Posts: 100

Location: California Zone 10b / Wyoming Zone 3b

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posted 1 month ago

I checked my copy of Rainwater Harvesting for Dryland and Beyond volume 2 and it says terraces without retaining walls (essentially a swale) are only suitable at slopes of 3:1, 18.4 degrees, 33% or less.

Terraces with retaining walls can go up to 2:1, 26.6 degrees, 50% so that may be what you need to do.

Randal Son

Posts: 17

Location: 10 Miles ESE Walla Walla WA 46°N 118.11°W (Elev. 2195 ft)

posted 1 month ago

Thanks y'all for considering my question and taking your time to help!

I've just finished Mark Shepard's new book Water for Any Farm, and am getting some T.A. from NRCS. I won't be doing any earthwork until next year, as I now have the cart BEHIND the horse. :-) Meaning I have a lot of thinning and pruning to do before I can even start to mark my contours.

5 Acres 25 degree west facing slope, conifer dominant on rocky silt/loam over basalt.

bruce Fine

Posts: 777

posted 1 month ago