Sepp Holzer Style Spring Terrace - PTJ Artifact!

How much of a grade is required for a spring terrace to function?  Is it a dramatically-sloped-land only sort of technique?

Beau Davidson wrote:How much of a grade is required for a spring terrace to function?  Is it a dramatically-sloped-land only sort of technique?

You need a certain kind of geohydrology for a spring terrace to work. If you have those conditions, a somewhat steeper slope (up to a certain point) will likely improve performance, all other things being equal. But even a fairly gentle slope could work if the underlying geology was just right. The performance of a spring terrace is, to a large degree, more dependent on the presence, depth, and topography of an impervious subsurface layer than it is on the surface topography.

If the site is too steep, then the likelihood of the topography of the subsurface layer being ideal goes way down. Unless, of course, the reason for the steepness is that there is a cut that exposes subsurface layers. You may have seen that occur in a location where a road was cut through a hilly area, and a hillside was cut to allow the road to go through. In some cases you will see water flowing out of a couple of spots in the cut. This is where water is seeping down from the surface above, hitting an impervious layer, and then running "downhill" along the surface of the impervious layer until it reaches daylight at the cut. In many ways, a spring terrace is working on the same principle; we are just digging down to intercept the run-off instead of cutting away the side of the hill to expose it.

If I'm understanding correctly -

Is it fair to say you would look for a spot where you can create a slight downhill path from an impervious layer to daylight?

With all things being equal on a project like this (I e. appropriate soil conditions, etc) would it be best to install terraces on the  shorter &steeper vs longer w/ less slope aspect of the property?  The property I'm working on is approx 336 ft by 660 ft, just trying to develop enough water flow to establish and orchard.  Similar climate as Missoula but less heat in the summer/ cold in the winter.

Dave Dahlsrud wrote:With all things being equal on a project like this (I e. appropriate soil conditions, etc) would it be best to install terraces on the  shorter &steeper vs longer w/ less slope aspect of the property?  The property I'm working on is approx 336 ft by 660 ft, just trying to develop enough water flow to establish and orchard.  Similar climate as Missoula but less heat in the summer/ cold in the winter.

Maybe instead of short/steep vs long/flatter, the better way to think about it might be to look for the location with the largest productive watershed area uphill of the collection system. If you think you have a good candidate location, dig a test pit to see if the sub-soil conditions are correct and whether you see moisture seeping out from on top of an impervious layer at a depth you can work with.

As we have been getting ready for the PTJ, I put together a sketch of the Spring Terrace and then Chase turned it into a set of nice graphics. I will post them here to assist in further discussion.

This concept is very new to me.  Why do you need terraces?  Why not just install a pipe on the second (bottom) half of a hill?  

On another note...I'm signed up for the PTJ and I'm trying to decide which events I will attend (hoping I could get a golden ticket still though).  I really want to learn something that I can use.  I'm sure I can *use* everything to a certain extant, and sometimes just knowing about a thing opens a door at a later time.  Does anyone have any advice as to how to choose what to attend at a PTJ?

The terraces catch and sink rainwater into the soil of the slope, where it would otherwise travel as a surface flow.

Is the objective to get a set of these built at the labs? I'm really keen to learn how this turns out. I'm not aware of anyone other than Sepp trying this and getting good results. I worry that his write up may be a quirk of his geology.

Peter Chan wrote:This concept is very new to me.  Why do you need terraces?  Why not just install a pipe on the second (bottom) half of a hill?  

The purpose of the terraces is to help get water to infiltrate into the ground instead of simply run off down the surface. The steeper the slope, the more prone to run-off the water will be for a given type of soil. The terraces stop the water and allow it to soak in. The water then gets filtered and as is able to pick up some minerals on its way through the "earth body" (as Sepp calls it).

If you were to just try to capture the water as it runs off across the surface (called "stormwater" at that point), it would be full of nutrient load and microbes. This is not ideal for storage or for drinking.

For water to sit in a storage tank for a while safely, ideally it should be as free of nutrients and microbes as possible, and not be exposed to sunlight. Without nutrient or sunlight, the microbes don't have much to work with, and consequently won't tend to grow.

Michael Cox wrote:Is the objective to get a set of these built at the labs? I'm really keen to learn how this turns out. I'm not aware of anyone other than Sepp trying this and getting good results. I worry that his write up may be a quirk of his geology.

Paul wants me to try an installation on the lab. The first thing I pointed out was that I'm not at all sure there is anyplace on the lab that has the proper geohydrologic conditions for it to work properly. So we agreed that I would do the following:

1. Explain how a spring terrace works, what conditions it requires, and how to tell if you have those conditions.
2. Take everyone out on the lab and evaluate possible locations. Bore test cores and/or dig test trenches to determine sub-soil conditions.
3. If we find a suitable location, install a spring terrace there. If not, do a small-scale demonstration of the process of installation.

It isn't actually all that unusual for there to be an impervious layer in the soil strata somewhere in the first 20-30 feet. If you have a good slope in much of the temperate zones, then there is a fair chance that you might have a relatively impervious layer (either an impervious form of bedrock or a clay layer) somewhere underneath. The more rare condition is having that layer shallow enough towards the bottom of the slope that it is practical to trench down to it and install the weeping tile and gravel.

The next time you see a place where a hill has been cut to allow a road through, take a closer look at the way the strata stack up. You may even notice places where water or moisture are seeping out. It may come out primarily at specific points, or it may be a slow seep all along a seem. That is the kind of thing the spring terrace is trying to intercept and harvest.

Alan has located a potential Spring Terrace site and dug a test pit to review today.  Fascinating process!  I am hoping some participants jump in here with their accounts of the process.  In the meantime, here are some images from Jeff's bootcamp journal.

It maybe a trick of the camera, but that land looks fairly level. My understanding was that spring terracing required a reasonable slope to work over?

So how did it go? I agree somewhat with the previous poster, that land looks very flat for the source spring, you'd have to run a VERY long pipe . . .
If I've understood what you are trying to do, it's kind of a cross between piping a spring, and a mini water mine?

Aha! Silly me! The link is near the top, in the first post, in between the photos. XD

I saw links to the PTJ and a thread on Sepps spring but nothing in this project. Did y'all get water?
Daniel

Has anyone else tried this successfully?

Daniel Kaplan wrote:I saw links to the PTJ and a thread on Sepps spring but nothing in this project. Did y'all get water?
Daniel

Daniel Kaplan wrote:Has anyone else tried this successfully?

Sepp Holzer got 400 gallons a day from his spring terrace the first year, increasing since.  

The geohydrology we have surveyed at Wheaton Labs so far will support this.  Paul is thinking it will be a prime candidate for a humus well, a similar installation.

The Low Tech Laboratory movie covers this in-depth.