Wednesday, April 16, 2008

A few more pictures, by popular demand...

My mom asked where the vault is in relation to the trailer, so I offer you this shot to help illustrate. This picture is shot from the top of the trench looking down, before we finished the trench or put the pipe in it. The vault is just to the left of the trailer (it's not installed in this picture, but you wouldn't be able to see it here anyway). it's actually about ten feet from the trailer, so very close.

If you look at a closeup of this picture, you can see my solar compass. This is something that Quentin Branch showed us how to do at a rammed earth workshop he taught last year.

I'm afraid the composition on this shot is quite poor - it looks like it's a picture of a weathered agave flower stalk lying on the lovely red dirt. In fact, the important things to look at are the foundation stake and the little bamboo stakes. This is why you need the close-up. What you do is that you put the stake in and get it as close to vertical as you can with a level. Then at about 11:00 you start putting bamboo stakes in the ground at the top end of the stake's shadow. Every ten minutes, you put in another stake.

At some point, it becomes clear which stake is closest to the big stake. This stake is the one that's closest to solar noon. The line between this stake and the big stake runs across the axis of solar north and solar south. Why is this important? If you face your house due south, then the windows on the south side will be shaded all day in the summer, and sunny all day in the winter. You can use a compass to guesstimate this, but magnetic north is a bit off of solar north, so it's good to do it the hard way. The cool thing is that I've done the solar compass several times, and I've gotten quite consistent results, so I think I'm doing it right.

Septic tank in, Water vault in...

Today a lot happened. Fortunately I was able to watch most of it from the window of the trailer, but there was some fun work for me to do too.

The big event was that at about 9am, Jeff showed up with his big earth mover. We unplugged the trailer, he drove across, I plugged the trailer back in, and he proceeded to clear a space downhill of the trailer for the septic system. I asked him to avoid a barrel cactus right near the septic site, and he very deftly did so. He also kept a juniper tree in the middle of the septic field - it looks a bit lonely there, but I'm sure it will become tall and stately with the added soil nutrients...

By early afternoon, he had a hole dug for the septic tank. Here's a picture, but this really doesn't do it justice - the hole you're looking down into here is about ten feet deep. You can see some rocks down at the bottom - Jeff had to climb down and remove the rocks to avoid the possibility of the tank cracking when it settled on them.

What you're seeing here is after Jeff leveled the bottom of the trench. It looks trapezoidal because of lense forshortening, not because it's actually that shape - the hole is pretty close to square.

Here's the tank on the truck, backing up to the hole. The truck has to back up quite close to the hole, and then the driver puts down stabilizers - the scissor-like assembly underneath the bed of the truck.

Here the tank is suspended over the hole on the boom on the back of the truck. Notice the quality of the finish on this tank - I'm used to seeing tanks that are pretty rough around the edges. Jeff gets his tanks from a guy in Saint David - Dad's Septic Tanks. I wondered why he'd do that when there are several places closer by that sell them; after looking at the quality of the tank we got, I guess I know.

They hold the tank with a single crossbar that's threaded through two rebar hooks; the entire weight of the tank hangs from these two hooks.

The tank descends into the hole, suspended on a steel cable from the end of the boom.

There was a bit of a problem putting the tank in - Jeff had carefully leveled the part of the trench closest to the trailer, but it was a little rough on the edge farthest away because that wasn't where he wanted the tank to go. Unfortunately, when the tank went in, the guy who delivered it couldn't get the truck to back up that far, so the tank wound up having to go toward the wrong end of the hole, which made for a bit of fussing to get it level.

Eventually Jeff was satisfied...

This is what it looks like out the window of the trailer, just to give you an idea of how close Jeff got it to the trailer without once digging a chunk out of the side of the trailer. He's really quite good with his backhoe. I'm very happy with his work so far - apparently David was right to recommend him.

The other project that needed doing today was the installation of the vault for the water system. This is a simple wooden box into which the main shutoff valve and the particulate filter go - there's a fair amount of dark particulate matter in the water here that needs to be taken out so that it doesn't wreck a seal in the pump. The filter is about 24" tall, so there's plenty of depth for it in the box. David has a clever system where he puts a slip joint on either end of the filter; to take it out, you just undo both slip joints and lift the entire thing out. Then renewing the filter is easy.

This is how the vault connects up to the trench. The vault is temporary, at least for now, so the water line is actually coming in above ground. This will need to be moved below ground or insulated before winter comes. My eventual goal is to have the water system in a concrete bunker on the eastern wall of the house, so that will mean we'll have to move the vault after the house is built.

What you don't see in these pictures is the hole Jeff kindly dug me with his backhoe. It took him about ten minutes to scoop out a hole big enough to put the vault in; I actually had to build up the bottom of the hole to make it work. I also had to dig a really huge wall out of the side of the hole to square it off so I could install the box, which was really a huge amount of work, because the soil right at that point was a really good clay - you could probably wet it and make pots with it.

Once I had the box in, I started burying it; a few minutes later, Chuck Vedova innocently wandered by to give me a CD, and because he's such a nice guy he offered to help me fill the hole. This was a huge boon - I was exhausted by the time we got it filled in, and I have no idea how I would have finished it myself in the time allotted. It's been nice working on these projects as a team - first with David, and then with Chuck.

This is a picture shot from the bottom of the trench, and the entire trench is actually in this picture. The top of the trench is to the right of the far right corner of the garage that you see off in the distance in this picture. The T in the pipe for the second building site is just below the garage.

Monday, April 14, 2008

Putting the pipe in the trench...

On Friday David and I spent some time on the water trench. The trench is quite long, and the pipe we're putting into it is a 2" diameter plastic pipe for potable water from Nu Mex Plastics in Roswell, New Mexico. This is pipe that's intended either for burial or just running overland on the surface - since water sources in Arizona tend to be fairly far apart, long runs for water supplies are fairly typical, and this kind of pipe makes a lot of sense.

The pipe is black, supposedly safe for potable water, very thick (you wouldn't want to drive over it, but it's not going to perforate easily). It cost us just under a dollar a foot, and comes in 100' and 500' rolls. It turns out that they make more than one version of this pipe, and the version we got is for fusion welding, which is a process whereby you join two lengths of pipe by essentially heating them and melting them together. Technology we really don't have. So we're having to do a makeshift job, which hopefully will work fine, using a heat gun to soften the pipe so that we can insert a metal fitting into each end, with the idea that the pipe will then relax around the fitting and form a strong seal.

Unfortunately, we didn't have a strong enough heat gun, so I came back to Tucson to get one - still need to make a run to Home Depot to see if they have something appropriate.

The process of getting the pipe into the trench was something I'd frankly been dreading - the 500' reel was really a lot of plastic. David or I probably could have gotten it edge-on with a lot of work, but even for the two of us it was a bit of a strain to do that, so with one person it would have been brutal. The pipe is flexible, but only in comparison to PEX or PVC pipe.

My original plan was to just roll the entire spool up to the top of the hill and then roll it down the trench, but I was feeling pretty uncomfortable with that - I was afraid that it'd cave in the trench. David had thought to build a spool to put it on, to make it easier to manage, but it still seemed pretty chancy.

So we decided to try just unrolling it up the driveway, and then carrying it over to the trench and dropping it in. This turned out to be quite a bit of work, but it did work - we rolled it to the bottom of the driveway, took off the outer ties, and started rolling it up the driveway.

At the beginning it was really hard to keep it from falling over, but not as hard as we expected to prevent it from sproinging out like a wrecked spring. With a lot of effort, we were able to unroll it to the point where the inner ties were exposed, cut them, and finish unrolling it. It was so long there wasn't actually room for the whole thing on David's driveway.

BTW, by outer and inner ties, what I mean is that the spool was tied twice, once around the whole spool, and once around the innermost probably 200' of pipe. So the inner part of the spool remained cohesive for much of the unrolling process. By the time we'd gotten to the inner ties, the spool was getting a lot easier to manage.

This two-step unrolling process is probably what makes it possible for two people to unroll the coil without a spool to hold it together; otherwise I think it would have been all over the place. As it was, a good part of the effort of unrolling it was just keeping it together, and we were fairly winded by the time we were done.

When you're unrolling one of these spools, it's important (as David pointed out) to start with the outermost end, not the innermost end. I'm sure I would have thought of that if I'd been on my own....

One other thing that I didn't think to do when the spool was delivered was to look for damage - it turns out that the coil had been mishandled at some point during transportation, and there was a deep cut in the outer wall along the inside of the coil. Fortunately, this was fairly close to the end of the coil, and we were able to cut the pipe at that point and still had enough left for the job - we only lost about 50' of pipe.

Once we'd cut that down, we cut off 80' of pipe to get to the first home site (our site is the second site, quite a ways down the hill from David's house; the first home site is just down the hill from his house). With Nicole's help we were able to just pick up the pipe and carry it to the trench and drop it in - it was really very easy.

The next step was to get the rest of the pipe into the trench. For this, we decided to try just dragging the pipe along the ground and laying it next to the trench, and then dumping it in as a second step, so as to avoid dragging the pipe across the edge of the trench and caving it in.

The main challenge here was that the driveway has two bends in it, and I had to shuttle back and forth across the nearer bend feeding pipe to David to prevent the pipe from straightening out over the bend and tearing down a lot of vegetation or getting snagged. It felt a lot like what you might imagine it feels like to haul a fire hose, at least based on videos I've seen of people doing that - you're holding onto the pipe with all your strength and leaning forward to push it.

Because the trench goes through quite a bit of vegetation, we had to lift it over the vegetation to avoid snapping off bits of cactus and limbs of mesquite or creosote bush. Once we had it pretty much in place, we dumped into the trench with minimal fuss. And we now have a pipe in a trench all the way from David's home site down to the trailer, probably 400 linear feet away.

All that remains is some plumbing and a bit of carpentry to make a vault for the particulate filter.

Friday, April 11, 2008

Digression: composting toilets

Will asked about composting toilets. Composting toilets are something I've been interested in for a long time, and that we've looked into a bit at DM. The executive summary is that when they are the only thing that will work, they're an attractive solution. They are a good alternative in a situation where you can't put in a septic system. They may also work better in situations where you have very a very tight water budget.

But if you have a choice of going with septic, you're probably going to prefer it. You don't save much money over a septic system by going with composting toilets, unless you are in the sub-1000-gallon range on your septic system and thus are overpaying heavily (because you can't really buy a smaller tank).

The really nice composting toilets are quite attractive, but the maintenance varies from a really lot to kind of a lot, and installation is a real problem. The waste has to wind up in the composter, which means that you either have to carry it there, or you have to have the composter under the toilet.

The composter is not small, so if you put it under the toilet, either you have to raise the toilet up on a throne, or you have to dig a cellar to put it in. Either way, you need to be able to get at it for maintenance, so that adds cost. And the ones that turn the waste automatically aren't cheap. So you don't wind up saving money over a septic system - multiply the cost of the composter and the installation by three in the case of our septic system, and you have a budget of $1300 per toilet. Good composting toilets, counting installation, cost more than that. So septic is cheaper for us.

You can do a really cheap composting install where you just have a litter box under the toilet that catches the waste, and then you carry the waste out to an outside composting system. But that's a big pain, and you probably don't want to do that if you don't have to. In a situation where you can't put in septic, or don't want to dig in a throne, this is a viable alternative, but it's not something that's going to catch on like wildfire - you have to have a bit of tapas to be able to deal with it.

On top of that, you have to do something with the waste water from your sink, because it's considered black water, not grey water. There are ways of dealing with it, but they involve variances that will be hard to get during the permitting process. If you have the time to prepare and make a serious case with the health department, it may be worth trying, but if that sounds like more work than you're willing to do, it's probably best to avoid it.

In our case, our perc test was a smashing success, and we have ample water, and a willingness to innovate with rainwater catchment and grey water, so we just don't feel like the compromises and cost of a composting system are the right choice. But we may well consider a composting solution when we set up our retreat cabin.

Thursday, April 10, 2008

Trench finished, septic coming, planning the foundation

David measured the distance along the trench the other day at 415 feet, of which about 25 hasn't been dug yet, so it looks like I dug about 400 feet in under 20 hours with the Kubota. That's 20 feet an hour, which is either really pathetic or really great - I have no idea which, not being a professional.

I haven't blogged about it in a while because it's been mostly routine. But at this point the trench goes from David's office all the way down to the trailer, with about an eight foot gap between the trailer and the end of the trench. I don't think I'm going to extend the trench at all by the trailer until the foundation's in - where it is is fine for a temporary installation. There's a bit more work to do up at David's office, because it turns out that I started the trench at the second flag from the junction box, instead of the first flag, and that was a difference of ten or fifteen feet.

We've got a pretty clear idea of where everything's going on the site at this point. We're going to put in a 1500 gallon septic tank and about 240 feet of leach lines, in three trenches. The septic will go fairly close to where the trailer is now, and will handle the output of as many as three houses - ours, a casita we're building, and another casita that a friend may build. It looks like the septic's going to come in a hair under $5000, which is a bit more than we'd budgeted for a 1000 gallon septic system, but I think worth the extra cost.

I do not yet have quite enough information to dig the foundation, but it's very close at this point - I think we will be able to start digging in another couple of weeks, and hopefully do the first pour toward the end of May. Right now, the plan is to do three pours - a footing, a stem wall, and a slab.

I keep feeling tempted to do a monolithic pour, because it'd be fewer trips with the cement truck, and because it's what everybody does in Arizona. But I haven't done a foundation this complicated before (I haven't done a foundation at all by myself before!), and the advantage of doing it in three steps is that I don't have to have everything perfect all at once, and each step will be a lot more straightforward. Maybe after the foundation for the casita and the main house are done, I'll feel confident doing a monolithic pour next time - we'll see. I suspect these two foundations will not be the last that I do.

By the way, if you're into saving the world, there are some interesting articles linked from the ResearchBlogging site that I thikn are worth reading, in the "Recent Interesting Articles" box to the right. ResearchBlogging is a fairly high intensity feed, and so I never read all the articles that I could on it, but a lot of really good stuff comes up. A lot of blogs are just people talking about their speculations, prejudices and (if you're lucky) experiences. So I think it's really valuable to read some things that are actually grounded in research from time to time...