Zach - I have been thinking a bit about your earth powered
greenhouse thread and your comments about my property possibilities.
The original greenhouse is actually in a location with a very high water table (5' below grade) and it has provided an immense benefit to the greenhouse. The ground water provides a temperature and humidity buffer. If the water table is even higher than this (as it sounds yours might be) then you can take a two pronged approach. First berm the greenhouse above grade as much as possible. If I were in your situation I would put in a pond and use the excavation to create a big berm around the greenhouse. As long as the berm angle is 1:2 or shallower then you should get the same heat benefits. The other thing to do would be to add a french drain (or several) to reduce the tension on the foundation. This would drain the water around the foundation into the pond.
My lot is an urban lot that is pretty flat. I used Google Sketchup to do the 1 foot elevation intervals, but not sure how accurate it is because I get different results depending upon how zoomed in I am. Regardless, there is a slight elevation drop from the street above me, in my
yard, maybe 2-3 foot over 125 foot or so. Where the
water tends to really pool is just beyond the
greenhouse (on the south side) and I have thought about possibly putting a small
pond there.
So my question really is...have you ever tried to combine the Krater Garden and the greenhouse shown in that thread. I live in zone 5B, so I definitely still get winter and here is what I was thinking.
* What if I dug down for a
pond and built up the edges like a Krater garden, using the north edge of the Krater as part of the earthberm for the greenhouse? I am thinking you could gain the thermal insulation from the earthberm and the
solar gain from the reflection off of the Krater pond.
* Then, to take the idea further, what if I installed a small pond or "stream" that had a walkway over it in the greenhouse that was fed by a Holzer monk system from the Krater pond outside? You could put the monk down in the spring and fall when it is wet to even the level between the pond in the greenhouse and the pond in the Krater. If you hit a dry spell in the summer and wanted the water for the greenhouse, you could turn the monk up so as to not let the water drain out of the greenhouse and into the outside Krater pond.
* With the Krater facing south, have an overflow for the pond, which I would also think would be an area that the cold air could flow out on the western side of the Krater (my yard has a little natural fall on that side). Possibly plant some tall grasses on or around the over flow to help make sure that it doesn't wash away if a very heavy rain comes and also as a little bit of a wind break for that opening in the Krater.
* Try to shape the Krater to be like a heat trap with parabolic shape, opening on SW side.
* Additionally, what if I were to get some large rocks to put in the Krater bottom somewhere in the edge of the pond to help with heat gain.
* Being in an urban enviroment, I am not sure what fit the
local township (and neighbors) would have if I put in an actual pond. Utilizing the starting ideas above, what if you were to fill the Krater "pond" with small stone and then put a layer of landscape fabric over that with some soil over that (I think Paul came up with an idea like this) so that the "pond" is hidden. I think you could still do the monk and put a drain pipe in the overflow that I mention and it would be safer for any children that might wander through my yard. Possibly could still put a big old rock or pile of large rocks in the center of the "pond" for more thermal gain.
* Here is a rudimentary sketch to try to explain what I am thinking.
So, am I even going down a path that makes sense or would work? Shoot holes in it, suggest improvements, any thoughts would be appreciated.