The First Test Borings
Submitted by admin_green on Mon, 10/05/2009 - 09:05
It's what's underneath that counts.
When you're trying to build in a way that minimally impacts your environment, one of the inconvenient facts you face is that your environment...which was here first...hasn't necessarily conformed itself to your specifications. You're then faced with a fairly stark decision:
- Plan A: Modify it. This is the "traditional" human approach to the problem. Bully nature out of the way until it does what you want it to do.
- Plan B: Modify your plans to work with the environment you've got. This is the goal of sustainable building, but is often easier said than done.
So we awaited the first test drillings of the Green Leaf Inn property with some trepidation.
Map of the test borings for the site. One boring was done at the location of the wind turbine (green), the rest at the corners of the proposed new buildings (red). Click to see full size image.
You can find the full report for the wind turbine boring by clicking here.
You can find the full report for the borings for the new buildings by clicking here.
We are gradually coming to grips with two key differences between the way humans look at the world and the way that the world actually works: we think short term, one to five years down the line, while the world works long term, with processes happening gradually over hundreds and thousands of years; and we think in terms of our immediate surroundings, while the world is all one huge interconnected system. So what has traditionally happened when we take the Plan A "modify nature to fit our goals" approach? The results have worked within our limited perspective, but caused problems...sometimes catastrophic problems...farther afield in space or time. The problems which were there from the start manifest themselves gradually over time, or just slightly beyond the nearest horizon.
Out of site, out of mind...we're not going to build the Green Leaf Inn that way.
If we are going to try Plan B...conforming out plans to work with existing environment of the land...our prime concern is the movement of water. The landscaping of the grounds will do a good job of responsibly managing water at the surface. But what happens below the surface is almost impossible to control. It is also critical to the success of our building.
Water under ground is pretty simple: it moves when it can, stops when it can't. It is pulled down by gravity and pushed in different direction by differences in pressure. Where the soil is loose and porous, it flows; where the soil is firm and rocky, it stops and pools.
Water under gound is also a headache for building. Remember, it's the "universal solvent;" it interacts with just about every substance known to man, generally working to weaken them. We have created a few substances that can resist it: PVC and ceramics, for instance, as well as stainless steel; but the process necessary to create these doesn't have the best environmental record. Removing it from your surroundings quickly gets you into Plan A territory, and often runs afoul of the whole "nature works long term and globally" problem...if water was there to begin with, it's probably going to come back eventually.
We have two areas of concern. First, the wind turbine needs deep support sunk down into firm, stable soil to keep it standing tall and strong. Second, wet basements are not a desirable feature for a bed and breakfast inn.
The test borings show us what we can't see with our eyes; what's down there. With test borings, you drill down fifty feet (or as far as you can go before you hit solid rock) and take periodic samples to give you a side view of the "soil layer cake" that lies beneath the surface.
We knew, from our earlier water studies (you can read about them here) that our soil is fairly moist due to runoff from the farmlands to the north (again, the whole "nature is one big system while humans think as far as their fences issue). The question was, how moist?
The answer came back...not great, but not terrible. Our soil is pretty much what you'd expect for this area: a lot of clay and loam, right down to 42 feet, where they hit so much rock they had to stop drilling (people from Wisconsin are very familiar with the concept of digging up rocks). They hit water in a couple of spots as close as 4-7 feet. This might be "perched" water...pools that have formed on top of dense packs of soil...because this is well above the depth of the local water table.
This shouldn't be a problem for the wind turbine. The base will be an oxagonal concrete plug that will go four feet deep, which puts it above the water. We will probably have to do some soil conversion around it: taking the existing soil, making it more porous so water will flow through instead of pooling, then replacing it and packing it down to provide a firmer footing.
For the new structures, we will have to consider either raising the foundations slightly higher (rather like lifting a skirt to keep it out of a puddle), or taking added steps to waterproof the foundation. A lot of this will depend on tests to determine whether the pooled water near the surface is a long-term (it was deposited there long ago and has been sitting there ever since) or a short-term (the pool is being constantly fed by fresh water) situation. We will probably need to drain som of the pools and see how quickly they refill, then make our decisions based on what happens.
Nobody said Plan B would be easy. But going green, especially this early in the game, is going to mean making a lot of choices that aren't the easy one.
