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.


Anonymous Mummy said...

Wow! I didn't realize I was holding my breath as you described your struggles until I started breathing again. Congratulations!

Monday, April 14, 2008 4:49:00 PM  

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