Steep Swales and Sprinkler Pipe Inquries

Good day Permies,
First post, so here I go. Quick background: I have been very much interested in the techniques and teachings of Permaculture and have been educating myself through online videos and information for the past couple years now. I have purchased my first house in southern California and purchased a house on 1/3 acre, and am starting from scratch as the yard (especially backyard) is bare.

I have a steep slope in the back yard about 16' deep x 65' long (more or less) with a retaining wall at the bottom, the house came with 5 small citrus trees laid out horizontally spread across the back slope, which has a turn towards the front of the house at the top. In preference to the steepness of the hill and the coming El Nino rains ahead I would like to do two swales on this slope. Unfortunately, the small citrus trees are not perfectly on contour and when I used my A-Frame level and marked out the contour of the swale it did not line up with them. Meaning that the one tree is in front of the berm, the second is in the berm, the third/fourth/fifth tree are in the path of the swale itself. While starting to dig the swale (since its my first) I've encountered some issues which are listed below.

Issue #1:
While digging, I have hit (and broke) a sprinkler line which feeds these trees, however this sprinkler line follows the trees and in doing so passes from in front of the berm, to into the berm, crosses the swale to the backside of the swale.

Issue #2:
while digging out the swales themselves, it was going to prove harsh on the trees that are located in the path of the swales as I was going to be digging below their crown, which would most likely kill the small trees in the end.

Issue #3: Need to design best possible way to have spillway / sill leave the hillside and to get down over retaining wall.
- There is a sloped section of the retaining wall on the right that comes down to ground level on the right hand side, but bypasses the rest of the backyard completely.
- There is an already eroded part of the retaining wall/slope on the left which can possibly be piled with rocks to prevent erosion

Options:
1# - Dig the swale as intended, removing the sprinkler line across the hill and trees ultimately as citrus require large amounts of water which would be better placed on the flat portion of the back yard.

2# - Redesign and relocated the swales, have a very small short swale in the corner of the hill and possibly two thin swales below the citrus trees.

3# - Other?

some pre-conceived thoughts:
- Swales filled with wood chips and be large enough for a pathway on the hillside
- spillway / sill for top swale be located on the right and second swale spillway / sill to be located on left that can drain through a rocks as it makes its way over the retaining wall to diminish erosion.


Thank you everyone, hope to hear some personal experiences on swales on steep slopes and also others encounters with irrigation lines and pipes

Welcome to Permies!
We are so glad you are here sharing your permaculture dreams . . . .

I love your plan for swales on that hill side, however my swale experience would not be applicable to your situation (different climate altogether), but some fun ideas I could brainstorm are:


(1) Raise or block-off your spillway / sill from the ground to prevent any erosion. I'd run it all to one side. Some examples include a series of water basins that spill from one into the next one set just below (functional art). Plaster and line your spill way, placing rocks in it to move the water in interesting ways and create mini water falls. You didn't say, but if you have room at the bottom you could put in a small pond or cistern that could store some of the water for use later.

(2) I would think fig and/or olive trees would work better for that slope in your climate, and citrus trees planted on flattish areas dug into the soil (submerged planter beds) with large seasoned logs buried underneath (Hugel style) to sponge and hold water through the dry seasons.

(3) Consider terracing/swaling to give you a little more planting room on the hill. This would be done after removing those trees and irrigation line of course, if that's the way you decide to go.

I look forward to watching this topic as it progress ~

You could do a series of "fish scale" swales around each tree. Each tree area gets its own swale and can be planted as a guild. Each swale can then be at different contours but the "arms" of the tallest swales can overflow into the next swale.

As a side note make sure the back cut the bench you house sits on correctly. It should slope away from your house and to the retaining wall and then flow out and around your hhous through a small channel . If this isn't done correctly and you start putting in swales where your are you may create water and moisture problems in your house

Eric Hammond wrote:You could do a series of "fish scale" swales around each tree. Each tree area gets its own swale and can be planted as a guild. Each swale can then be at different contours but the "arms" of the tallest swales can overflow into the next swale.

I didn't think about the small fish scale swales as the first layer of swales, and having them empty out into the standard full contour swale below that. The only issue I foresee in that is still running into the sprinkler pipes and heads when doing these scale swales, if i was to keep the 5 sprinkler heads on the hillside.

Eric Hammond wrote:As a side note make sure the back cut the bench you house sits on correctly. It should slope away from your house and to the retaining wall and then flow out and around your hhous through a small channel . If this isn't done correctly and you start putting in swales where your are you may create water and moisture problems in your house

Would you mind re-wording what you meant above?
I'm assuming you meant something along the lines of making sure there is a back cut to the swales for erosion prevention purposes and make sure the level spill ways for the swale(s) exit or are channeled away from the house and to the side so I don't have any water damage to the house.

Jami,
Thanks for the input, I was thinking the same thing for some rocks to create a waterfall/riverbed type situation. I would have to do some research to see how hard it would be to move the citrus trees and if they could survive the move if I did decide to move them to the bottom of the yard, and I would love to plant some figs and many more plants, but that is for a later time and topic. I'll try and keep an update on this swale(s) for now as I haven't been able to get back to them yet.

-Duncan

Eric Hammond wrote:
As a side note make sure the back cut the bench you house sits on correctly. It should slope away from your house and to the retaining wall and then flow out and around your hhous through a small channel . If this isn't done correctly and you start putting in swales where your are you may create water and moisture problems in your house


Would you mind re-wording what you meant above?
I'm assuming you meant something along the lines of making sure there is a back cut to the swales for erosion prevention purposes and make sure the level spill ways for the swale(s) exit or are channeled away from the house and to the side so I don't have any water damage to the house.

Good Point! - swales slow the movement of water allowing it to linger and perk down...... So is there a french drain behind your retaining wall at the base to deal with water in the soil coming toward the wall and house area? In my opinion - a balance between 1. how the water will escape the land with 2. how you will capture and hold water on the land needs to always be addressed. Along this topic you may want to not dig swales until you are ready for more planting/landscaping to hold that hillside firmly should a lot of rain fall in a short period.

When you create a "flat" spot on a hill or slope to build a house it's called a bench. Material is cut out of the hill and positioned downhill as the fill. This creates the bench. As you can imagine the fill side will never be as compacted or as strong as the cut side. Your retaining wall is the back of the cut. To prevent any erosion to the fill side and water damage to your house its critical that the bench is not flat, and that it is in fact higher on the fill side and slopes towards the back cut. Then a small channel placed at the bottom of the back cut that directs water around the house and off the bench in the front. Is that any better?

You explained it so well Eric,

- in my case our 'bench' is very wide and the backward slope does not exist, I don't know if it ever did or if things just settled to far. I do know that run off from the hill behind was not addressed and the buildings have suffered from underground water movement.