Planning a Hugelkultur Bed

I built 3 small hugelkultur beds this year in my garden. I am looking to build one or two larger beds for next year. I work for a heavy equipment operator and have access to a bulldozer, excavator,backhoe, bobcat, etc., as well as a very experienced and conscientious operator. I have access to rotten and green logs, our company does "fire clearance" work that generates a lot of logs. I have established connections with some local tree services for chipped brush as well as a local horse training barn. I am located in the foothills of California. The site I am thinking is a pasture with a very gentle slope to the east, and good southern exposure.

I am open to any advice on layout or construction. I am currently picturing cutting a trench with the bulldozer then ripping the bottom of the trench, to aid in water infiltration. I am planning on setting the sod layer to the side. Then using the track-hoe fill the trench with logs up to maybe 6' above grade? Again using the track-hoe place the sod on top of the log pile and then dress the top with the fill dirt, and composted horse manure. I was thinking about dressing the mounds with wood chips, I have access to about 200 yards.

The logs I have access to are primarily Ponderosa Pine, Live Oak, Black Oak, White Fir, and some cedar. All the logs are in a very large pile and some are rotted to the point of no identification. All the logs are in 6' lengths for legal transport. I have been able to I.D. and set aside all the cedar so far.
My primary questions are. How deep should the trench be? How deep should it be ripped? I have 18" and 3' rippers available. Should I do any amendments to the trench before the logs go in? Should I orient the bed East to West or place it on contour? What might be the ideal length and height of the beds? I am thinking fifty or so feet long and six feet tall.
Thanks for any help or advice,
Mica

Howdy Mica, welcome to permies. Sounds like you have a great plan so far. I am still learning about hugels myself. From some of the other threads I have read , people have mentioned the idea of having beds with breaks in them so that you do not have to walk the full 50 ft to get around them. Also some folks do them on contour some in all sorts of artsy shapes. One thing to watch for is the trapping of any cold air that will be moving down the slope. Might be a good thing where you are ? I would add all sorts of amendments as I built the beds ,myself. Sort of like a compost pile with logs.

mica,

Sounds like a great location. Good morning sun which is much better than afternoon sun for growing.

Once those big hugel beds are built you won't be able to till or amend the soil again.
So you should add as much amendments as possible when building.

In my own backyard hugels I was surprised by how much better plants grew in the beds which I dug in wood chips.
If you have the normal California foothills soil of bright red clay, I recommend 1 part soil : 1 part wood chips : 1 part manure&sod.

Whenever I've dug in wood chips it seems like a lot, but then a month later when I stick my hand in the soil to check it out, it seems like only a small fraction is left.
Just dug in 50% chips to some small holes a month ago, and now when redigging it feels like there isn't enough for optimum plant growth.

I have about 10-12 yards of manure on site for the project, I could get more but there would be transport costs associated. I was thinking that 10 yards of material would be minimal for a top dressing, could be wrong. Maybe it would be good to get a full transfer load, 36 yards, to layer in below and in between the logs? I could layer manure in with a backhoe while the excavator is moving logs. Seems like that would certainly be enough organic material. Would the extra organic material justify the cost? Associated costs would be moving a backhoe and a transfer truck to retrieve more manure. Probably three to four hundred dollars.
I have heard mixed things about burying wood chips, is there a general rule there? I was figuring on layering additional wood chips and manure after the beds are constructed.

My soil is fairly rich, black with lots of worms for about a foot or so, then clay. At least in that site most other areas on the property are clay.

Sounds like great soil for growing in without putting in lots of amendments. My comments were targeted for low organic soils.


Just a quick picture about wood chips in the soil.



As an experiment last year I dug in wood chips to a garden bed. At the end of the season I dug it up to look to see what the plant roots were doing.
The roots all congregated in pockets of soil with lots of wood chips (luckily, I didn't mix the chips in very uniformly).
The picture show two soil clumps that were just 4" apart in the ground. The clump with lots of chips had lots of roots. The clump with few chips had no roots.
So if the roots like wood chips, I figure the plants must like them too


http://lowcostvegetablegarden.blogspot.com/2012/10/wood-chip-soil-pictures.html

Thanks all for the input.
I will post some pictures of the site, test trenches, amendments, logs, etc. as I get closer to construction. It looks like a client may have us haul away her manure in the next few months, yeah.