I've got a leach field after a septic tank in zone 9, dry Mediterranean climate. Soil is heavy clay over rock, alcaline ph 8.5. Leach field is now a 25 meters open canal with permanent water.

I am allowed to clean the canal and do some earth works next Monday.

My plan is to cross the canal a few times so canal length is 3x or 4x what I have now. Then cover with gravel, fence it and plant something.

My goals:

Stop current mess
Not trying to reuse water
Get poultry forage and/or compost material from green filter plants that use the resource.

I've thought about comfrey, canna,thypha and ?

how about stinging nettle?

i want to do something similar with my current septic pit that seems at least one hundred years old. did you have to get plans cleared by the county or anything like that? little worried about that, and what designs they may approve for me.

Welcome to permies.

I think that Typha s. (cattails/bulrush) would be a good choice.
They thrive in wet places, produce masses of bulk, and provide nutrition (comparable to corn/rice) for the poultry.

See this Wikimedia page to see more uses.

John Polk wrote: provide nutrition (comparable to corn/rice) for the poultry.

What part do you feed to the poultry and how do you feed it?

John, in Zone 9 and the high pH I would go with trees that drop a lot of litter for compost and mulch, like a bottlebrush tree, that can be trimmed to bush size if you want. It's excellent for bringing in beneficial insects, and honey bees. Even if it goes a little below freezing it will be okay, but needs protection elsewhere.

And trees for firewood, like eucalyptus. Eucalyptus also improves the soil it drops leaves on, so it is good for compost while you're waiting for firewood, but don't put one near your house, garage or shed because the branches are brittle and will drop in wind storms causing damage. They have to be pretty old before they start dropping large branches, and if you chop them for firewood they won't be big enough to cause problems. You wouldn't have to fence these, either. Even if you don't use firewood except for a couple of months, you can always sell cured firewood and make some extra money. Eucalyptus is excellent firewood. These trees smell great, too, on a sunny day. Honey bees love to nest in old, large mature trees, the blossoms bring in beneficial insects. I just found one by the road not far from me with pink blossoms in the fall, I'm going to go get some cuttings off ot it.

Elaeagnus bushes drop a lot of leaf litter, but some have big thorns on them, so research what you want with that in mind. They hurt like the dickens, especially if you trim the branches, and want to haul them, even with gloves on, to somewhere else. I've got the silverberry, which has big thorns, I just have to be careful, but it drops great compost that is easily raked.

What part do you feed to the poultry and how do you feed it?

From Wikipedia: Many parts of the Typha plant are edible to humans. The starchy rhizomes are nutritious with a protein content comparable to that of maize or rice.[14] They can be processed into a flour with 266 kcal per 100 grams.[4] They are most often harvested from late autumn to early spring. They are fibrous, and the starch must be scraped or sucked from the tough fibers. Plants growing in polluted water can accumulate lead and pesticide residues in their rhizomes, and these should not be eaten.[15]

The outer portion of young plants can be peeled and the heart can be eaten raw or boiled and eaten like asparagus. This food has been popular among the Cossacks in Russia, and has been called "Cossack asparagus".[16] The leaf bases can be eaten raw or cooked, especially in late spring when they are young and tender. In early summer the sheath can be removed from the developing green flower spike, which can then be boiled and eaten like corn on the cob.[17] In mid-summer when the male flowers are mature, the pollen can be collected and used as a flour supplement or thickener.[18]
Agriculture

The seeds have a high linoleic acid content and can be used to feed cattle and chickens.

Interesting thread. I was wondering if bamboo in one or more of its' many varieties would be good? http://sustainablesmallholding.org/hardy-bamboo-and-chickens/ http://www.inbar.int/2012/03/bamboo-chicken-feed http://www.motherearthnews.com/homesteading-and-livestock/poultry/poultry-feed-zmaz10fmzraw.aspx

There's cattle around so I must fence. They like eucalyptus too. I prefer something smaller.

Bamboo is an option. We have mite problems with most.

Ok someone is not actually feeding cattail to their chickens. Maybe I'll try cutting some cattail heads if we still have any and put them out for the chickens.

John, I should have asked, how many people are contributing to this leach field daily? 1 or 2 would be quite different from 4 or 6. Trees are about the only thing that could use enough of the water to keep it in balance if there are 4+ people.

My neighbor has dozens of eucalyptus and runs cattle, they don't bother the trees, even the small volunteers at the base of them. I haven't even seen bucks rub their antlers against them. Of all the critters here that chew on stuff, I've never seen marks on the eucalyptus, just in case anyone else reading this thread want to try them.

The cattail (Typha) and bulrush (Scirpoides) species are the very best at blackwater remediation because they have oxygenating bacteria on their root system. I would consider willow as another feeder plant-for rocket stoves not chickens! The willows will drink tons of water and transpire it into the air. Comfrey is a good choice but should not be the primary browse of chickens... more of a supplement at max 10%. Nettles I like as an high nutrient source that is lot less difficult on the liver option. The area could also be planted with root cuttings and seeds of dandelion, and chicory as well, and other fodder plants. The chickens will eat those, for sure. I imagine if chickens were shown the soft inner shoots of the cattails and bulrushes they could be trained to eat that, which is a really great food that I enjoy.

Now about 3, but could grow to 5 people

I've got cattails in a grey water system, and the green tops die back, are not present for 5-6 months out of the year, so I've supplemented with other pond plants that the critters don't eat that are green all year. Pack rats chew off cattails, and make nests out of them, so you've got to have a lot of them, or fence them off with chicken wire. They also need to be in water, and don't do well in just wet soil, they want that much standing water. But they are fascinating plants. Even the fluff can be used as natural down in jackets.