Notes from Windward: #67
Questions Re Vermadise
Today's email has to do with Vermadise. I've been reading as much about it as I can so I think I might have answered some of my questions but I'd like you to confirm and/or clarity my assumptions.
It's 20' x 40' with the 40' sides facing west and east. I believe that the chicken run (width ?) is down the eastern side of the greenhouse and the workspace addition is along the north wall. So far so good?
Yes. The chicken run is 30" wide by 20' long, not counting the roosting shed.
Since you seem to carefully think things out I'm wondering why you didn't site the greenhouse so the long side was facing south. Were you concerned about overheating during the summer or perhaps minimizing the colder northside?
Actually, neither--although you're quite correct in that both are real concerns which are addressed by this layout. By the first of June, temps in Vermadise reach the point where we have to pull the plastic and replace it with shade cloth. With a hoop-style greenhouse, the only alternative I'm aware of is to use fans to ventilate, and it takes energy to do that. Since our goal is to see how much we can accomplish with passive technology, we go with the shade-cloth option. It takes a crew of four less than an hour to take down the plastic and put up the shade cloth so it's become just another of our spring/fall change-over rituals, like transforming our summer dump truck into our winter snowplow.
A "two-fer" is anything which enables us to fulfill two (or more) goals using a single asset, and it's one of the concepts guiding our effort to build sustainability into everything we do at Windward.
In this case, the assets we're trying to get the greatest use out of is land that's flat enough to grow food on, and water. Like it or not, health districts are reluctant to endorse alternative waste disposal systems. Windward is committed to being different enough to make a difference, but there's a host of new options out there, so it's important that we pick our battles carefully. And so, while there are a range of interesting alternative ways to deal with human waste, we've gone with the traditional combination of septic system and drain field that remains the solution of choice for most health districts.
As a result, Windward has eleven separate septic systems--some black, some grey--which handle our waste water. By necessity, the drain fields for those systems are located in some of our best soils, and as Erma Bombeck noted, "The grass is always greenest over the septic tank." By locating Vermadise on top of a drain field, we're able to get a double use out of that piece of land, and a double use out of moisture that would otherwise be lost.
We're not limited enough in our land so that we need push the envelope by growing food crops on top of our drain fields, but we are comfortable using that space to grow earthworms as feed for our chickens and fish.
Regarding the poly covering, are you still using a single layer to act as a failsafe if the snow load gets too thick? I was going to use a double layer envelope but I read that you are concerned about a collapse since you wouldn't be pumping heated air in between the layers of poly. Have you figured out a way around that yet?
Sort of. In our quest to see how many different systems we can shoehorn into that space, we've hung grow tubes from the pipe that runs along the peak of the hoop. In order to support that weight, we installed a pair of 4x4 posts to support the pipe, and that was enough to get us through the winter snows just fine.
I'm asking all these questions because the Vermadise concept is one that I'm been thinking about for some time but just not in the scale that you've created. I've wanted to combine systems like Joel Salatin does and was going to put together a Raken house similar to the one his son built but I believe that your Vermadise does it better by taking it a level or two beyond simply co-housing rabbits and chickens. I hope to have something completed by next spring so my big question is this, knowing what you know now about how Vermadise is performing what would you change if you were building a new one?
After giving that some thought, I can't come up with any thing that I'd want to do differently--the key being that this structure is where it is because that's where the county wanted the drain field to go. I expect that most of our greenhouses are going to be "two-fers" in that they'll be integrated with some other function, and therefore be blend of options.
For example, one of next year's projects is to transform one of our 40' insulated containers into a solar powered walk-in cooler/freezer. That structure will be oriented east-west in order to optimize the insolation (i.e. the amount of solar energy impacting the roof-mounted collectors). Given that, we'll want to install a "Solviva" style greenhouse along its southern exposure.
Notes From Windward - Index - Vol. 67