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Christopher Brown

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since Aug 13, 2012
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Recent posts by Christopher Brown

daniel smith wrote:The first strategy is to create a segmented series of separate relatively shallow swales, that are about 8' in length, with a wooden board that is essentially on contour to retain the edge?



Not quite.
One continuous level swale with alternating between non outlet zones where fills are, to outlet zones that have a wooden edge spreading the water evenly.

daniel smith wrote:The second strategy is to create a serpentine swale (again, relatively shallow) running down the slope with wooden boards along the edge. Are you also suggesting that I create intentional "erosion proof" spill zones that are reinforced with wooden boards and stones? (i cant fully visualize the specifics of your description here)



Not down, but along. 3% fall.

All this depends on how much rain collects and concentrates. If too much, you need to damm the swale up with wood like an irrigation trench until it spills onto a rock littered dispersal area in an appropriate spot. No wooden boards on the edge unless you go level with your swale for a short run to accomodate an outlet area with edge dispersal sheet flow over cut or natural slope with a foot or 2 of 2% slope leading to daylighting on the natural.

daniel smith wrote:I'm curious to understand how the hard edge works with a berm.... I had planned on having berms on the downhill side of my swales. In order to do this would the boards have to reach up to the peak of the berms (placed between the swale and the berm)?



Berms, fills, holding water on slope won't last unless they are well compacted and benched. Something tells me don't want to do that.

Alternately narrow benches are made and filled upon to a grade over the outlet boards by perhaps 6" and they are outside the swale filled on to the natural slope and a wider flatter planting area adjacent to the swale. It's important to cut into the mantle of soil. If you don't, the shedding action of the natural geology takes the water at original surface level just under your fills.

Think a carefully cut level swale with the dirt moderately compacted (1/2 have fill, 1/2 spill) on minimal benches into the slope below the swale. You could make a big template with a level on it out of 1x2"s & 1/8 ply to help lay it out so you know where the cut daylights for the lip of the swale as well as an idea where the cutslope above the swale will daylight out of the natural slope.

Take your water level and stretch out an APROX 50', set stakes level, bring the PVC in an get it APROX. perpendicular to the row of stakes hiked up on some sawhorses until its level, measure down to know the cut from natural to the lip, bottom and back below the cut slope. Pick your fill areas and equal them in length with spill zones. Get your mattox, shovel and wheebarrow or a mini excavator.
7 years ago

daniel smith wrote:Christopher, Thank you so much for your thorough response!

I just determined the steepness of the slope using http://www.mytopo.com/search.cfm?type=pns
(A really awesome tool that overlays topographic maps over google maps)

I've determined that the overall slope is 14% gradient, or a gain in 1 foot of elevation every 4 feet.



Hmmmm, you've cited 2 different slopes, 14% and 25%. 1v is 25% of 4h.

At 25% you'll have some erosion problems for sure if you try and hold water through rains in level swales on the slopes. No earthen edge will remain consistent until its well vegetated, even then. Limited volumes with outlet/spill zones on cut with a level 8ft 2x6 might work. Place fill areas between them, slightly higher.

A serpentine swale at 3% on a 25% slope will work well but break the concentrations up, or make it easy to do so with flow dispersal areas of small rock in the right spot if you have problems. These can be utilized temporarily with a level board dam across the swale, and an adjacent wooden spell bar starting with less water in the swale in the first year, depending on rain etc., vegetating then blocking outlets and raising levels the next year.

At 14% you have it made, but limit the volume in case there is a breach of an edge.

daniel smith wrote:This is the overall slope, however. In reality, the slope that is closer to the house is probably about 10%, whereas the slope farthest from the house is probably about 20% (the house is at the downhill most part of the property)

I have found a geologic report of Scotts Valley online. I have a difficult time ascertaining anything significant from the report, however, it does mention that the location is marked by "moderate to high landslide risk"
(if you feel so inclined, you can read the report [url=https://docs.google.com/viewer?)



- -

Well goog doc viewer is incompatible with my ancient browser. Oh well

daniel smith wrote:Now, if I understand you correctly, you are suggesting that the best strategy is to create swales on contour that have hard even edges all the way along, to prevent erosion and promote sheet flow is that correct?

If this is incorrect, please let me know what I am missing. If this is correct, could you point me in the right direction as to where I can learn to do this effectively?

Thanks again, your input is greatly appreciated!



Yes, if you are going for the most water possible. However, to hold water on a slope like that, hard level edges are vital to allow uniform overflow when they fill.

Not sure there is anywhere you can learn it. Best is probably to put one in at the bottom of the steeper area and see how it goes for year. Modify accordingly next year.

Doing things like this is all about procedure and sequence.
1) Make a plan. In your case a simple average section.
2) Learn how to use a water level, 50%27 of clear plastic tube with plugs and about 4 feet of air in it.
3) Figure out your cut/fill areas/locations. I mentioned the "outlet or "spill zones"

With 3), either your swales are all cut, meaning you are moving a lot of dirt quite a distance, or they are a cut and fill running combination, which means compaction and immediate planting well before winter rains is needed. The alternating outlet zone/fill area may work okay on either 14% or 25%. Dryer plantings can go on the higher ground between outlets.


7 years ago
Hi Daniel,
I posted the thread before yours in this forum. Slope angle is critical as well as geology. Go into the gullys and read the banks to see what underlying materials are. Examine nearby slopes for slides. Perhaps a neighbor with the same basic geology has a soils report describing the underlying formations. Slopes comprised of deep clay would probably, eventually be a disaster to saturate if they were over 30%.

Check the link in my thread to an "abney", to measure the slope angle which will be very useful over and over on your land. Two sticks with flagging at equal heights are set directly below/above, perpendicular to the contour, about 3' is good, and by sighting with the instrument on one, to the other, the angle is directly read.
Some have percent of slope as well as degrees. The best read direct to 10min. Conversion to percent from angles is not terribly easy, 20% for example is 11 deg, 18 min. Hacking around with polar to rectangular conversions on a calculator will get it done.

There is a program called "topo" which has all of the USGS topographic maps digitally scanned, which could be used to derive the basic slope angle as well as crude topography. You could also buy a quad map and calculate it from that.

A swale is basically a terrace that is too narrow for anything but water. Santa Cruz gets so much rainfall that a swale with a constant gradient will probably be needed or your swales will be over flowing. Without a hard edge for outfall, there will be a groove cut at some point by overflow and the swales water will not accumulate increasing hydrostatic pressure, saturating the soil below, so the swale is defeated in its purpose and erosion is the result.

Plantings immediately downslope from a small swale, that is about trail size, will see increased moisture, but once you start concentrating the flow, you have to keep it controlled or determine how to recreate sheet flow onto the slope below which is not easy. It can be done however by using a board set level at the downhill edge/end of the swale with gradient that gathers and concentrates flow for the water to spill over evenly.

An "on contour" swale will fill up and overflow. A keyline exagerates this by taking flow from a natural flowline and adding it to a slope. I've described what a slope with gradient does at the end, and switching back a gradient flowline on steeper ground in a serpentine path is sketchy. There are some tactics tho.

Once your average slopes are known, and the underly geology, then decisions can be made.
7 years ago
Greetings Permies:-)
I've been reading here about keyline swales, and finally found this graphic to clarify what is happening. The thread by Patrick Mann has some good references.

https://permies.com/t/16470/earthworks/Keyline-questions

But this graphic made the difference. The videos are quite helpful, even on their larger scales for visualizing the system.

https://permies.com/t/16470/a/5538/keyline%20concept.jpg

I've been an dozer operator, self employed, not "owner operator", but directing clients to rent needed machinery, for 30 years. I've worked as a surveyor for 25 years and for about 23 years I've generated custom large scale topos for construction, grading and drainage plans for a civil engineer.

I specialize in drainage on steep mountain roads as a operator. Finish drainage, by eye, from the seat of a dozer has been a focus that people really appreciate. I've recovered many roads here in these coastal mountains that were destroyed by the lack of drainage or improper drainage. My drainage works well enough so that I put myself out of work, because roads only need light maintenance of drainage devices after I'm done.
We have highly varied geology here that really provides huge challenges. Or, there is a 50 mile wide strip in the back country here that has no paved roads because there's no guarantee that sections will remain after next years rains.

I've just made a youtube channel and web page to attempt and sell video of grading and drainage work I've done from 2006. I need to support the political activism I do in pursuit of peace and environmental protection through defense and restoration of the constitution by American citizens using Article V properly, by preparatory Amendment. A .pdf about the strategy.

http://algoxy.com/ows/preparation_for_article_v.pdf

Back to dirt work. There is a link to my youtube channel from the page if there is interest in watching how I work. No downloads of the 90 min parts yet, I'm seeing if there is interest first.

http://docdirt.net

I also have developed ways of saving the natural seed bearing surface soils off to the sides, then bringing them back after the earthwork. A few smaller jobs about (300cu yds) were actually completed that were turned into county agencies by vengeful nieghbors because there was no permit. But when they were inspected by county grading officials, because natural grasses were sprouting everywhere (much water applied) and the owner was talking about "clearing and drainage", they could not determine what had been done, had no problem with anything, so left with no violation.
I suspect this method will work well for permies because the cost of topo and design will be a turn off.

Use of an abney to set grades with marker lathes and hiked up flagging http://www.ascscientific.com/8047-55abney.jpg is all that is needed along with a good operator having prodecdure and an eye for locating daylight points on cut slopes and toe points for fills.

Back to swales:

In about 1992 I started installing what I called the "Serpentine Swale" with a D6D cat that was available. It worked on slopes up to 20%, but with a 10' blade a lot of dirt was moved to get a flowline. They were installed to give water time to exert its hydrostatic pressure on sub soils and charge them with water just as the keyline. The original need was to get rid of outlets of water bars installed on ranch roads without erosion.

I was fortunate to have a house near enough on the first one to advise them to use it for a garden because I expected ambient moisture levels to raise dramatically. It worked in the fractured shale quite well and soon the area which hadn't really worked for a spring household crop, because it was dry and far from water. After the first year and the spring successes, they ran a small waterline to take a summer garden crop all the way through.
There was enough absorbtion, where the outlet, even in heavy years saw minimal erosion.

In 1998 I started making them in Mendocino county on a smaller scale with a high trak D4 cat, to stay away from steeper slopes where heavy cutting and filling was the only practical method. Also, as some of the posted videos here indicate, slope stability and integrity can be seriously effected over time adding mass water to a slope.

The "Serpintine Swale" has a constant fall of no less than 3% and max of 10% for a short distance, usually in a switchback.

I've thought of the "Keyline Swale", but in the steep ground I work in the chances of slope destabilization have often been too great to take the water of a natural flowline and move it out to a ridge. Also, the chances of over-run and question of "where the water goes" gets sticky. I would consider that in the right geology, it could be run back to the natural flowline.

In the examples of the videos here.

http://www.youtube.com/watch?v=_X-BMbLBozA&feature=relmfu
http://www.youtube.com/watch?v=rhATikyzLOo

The average slopes over distances between ridges and valleys/flowlines are not very great in those examples, so destabilization is not a great threat.

For steeper ground, which turns out to be the most affordable because of the costs and limits inherent to it, roads act as keylines, but running a flowline down a road will almost always destroy it. However, a road traversing a slope acts as a slope interceptor meaning flow concentrates and must be taken off. If there are flatter areas near the outlets of water bars, taking negatively drained flow, concentrated, to positive, discharging off the road downslope, then you have the situation where I developed the "Serpentine Swale" to deal with the water and erosion.

Hope this brings some loose ends together in determining how to increase ambient moisture for permaculture.
7 years ago

laurie branson wrote:We recently purchased land to farm organically and are in the process of trying to get a gravel road put in. The county is requiring us to put in the gravel road before we can get any building permits, so unfortunately the type of rural road Paul recently discussed in his podcast won't work for us. The road is about 800 ft long and will be 14 -18 ft wide (depending on how successful we are in convincing with the county that 14 ft is plenty wide for firetrucks because we will have turnouts) and will be going over pasture. Of course our contractor wants to use Roundup to kill the pasture that will be under the road, then laying road fabric down and then the rock. Please be assured we will NOT be using Roundup!

My research into alternatives to Roundup so far is vinegar, torching it, and/or tilling it under. I realize tilling is not a permie thing, but if it is going to be under the road I am thinking it would be ok. Would you torch it and then till it under? How about torch it and then spray it down with vinegar? If you just sprayed it down with vinegar, how much would you need and how long would you need to wait before covering it up? Any other advice/ideas?

Thanks!



I've been an operator for over 30 years. Currently I do mostly surveying and I work with a civil engineer.

I've found that using the largest dozer you can find and carefully cutting and piling any plant matter, then the layer of roots, and overex any wet zones, then mixing and compacting along your route will make the best and cheapest dirt road. I've found crowning to be a bit troublesome to install and maintain compared to a simple cross slope with swales or water bars, particuarly on roads less than 25' wide. When water bars are longer, driving over them is not really noticeable and they take little maintenance. County roads and logging roads tend to need crowning because of the width and log trucks do not want to go over the water bars. With a crown, one half the horizontal from the center so vertical fall easily built in creates a steeper cross drainage each direction with crowned roads.
Also with a crown you have to get the water across the road, meaning a culvert which is a fair expense on top of the rock. Over the years, depending on the slope and road grade, they can be a pain.

If possible pick a few areas near the roadway to be planted to spread that root bearing soil over the grasses where it will all breakdown and leave a very rich planting area.

What I've found works best is a positively drained road, but also in steep ground what is safest and works very well is a negatively drained road with a water bar that takes about a 35' long stretch and makes it positive. I get these working on dirt roads. Of course if they are driven on wet they turn into a puddle but still work if you compacted the bars well. In your case, leave grades low about 4 to 6" for the gravel and make sure the water bars have nearly 8" for about 15' where the flow crosses it. Mix some dirt into the rock to bind it together and stretch your rock. Compact it too. Each one of those outlets can be the beginning of a keyline trench that causes maimum saturation.

I do exactly as you say, 3" rock on the bottom with 1.5 and smaller on top.
7 years ago