Wednesday, March 1, 2017

Lowering the Main Irrigation Water Supply Line

Back in November, 2012, we excavated the East side of the backyard.  As part of that, we exposed the main irrigation water supply line, and to make sure it was well out of the way, we lowered it all the way down to the bedrock.  We had to raise it back up to interface with the existing pipe where we were not (yet) digging.

Now we are digging back to that point, from the other direction.

And today, we dug all the way over to where the pipe drops.

The objective is to dig out all the dirt and rock under the existing pipe, down to bedrock, and then re-do the linkage to the pipe on the East side to lower this section that goes along the center of the yard.

More digging exposes not just the main irrigation supply line, but also the line for Zone 5, and an old (unused) PVC line (which we have now removed).

 Using the jack hammer to break up and remove the rock that has been exposed, we can excavate all the way down to bedrock.

Looking at the far end of the trench shows how the previous work had to "step up" to connect with the un-excavated main supply line:

The first step is to remove all the old PVC pipe.   Then we lay new PVC pipe and couple it directly into the main water supply line. ($34.38 at Home Depot for PVC pipe and pieces).

This is a new 1.5 inch Schedule 40 PVC pipe.  It runs along the ground until it gets to the valve for the Zone 5 beds.  At that point we "tee" off to a 1 inch PVC line going up.

We continue along at ground level until we get to the end of the pit, next to the end of the River of Rocks.  At this point, we must once more "step up" to connect to the rest of the (unexcavated) main water supply line as it continues around the house.

Since both ends of the pipe are fixed, we have to do something to finish the last connection.  We used an NDS 1.5 inch Pro-Span Coupling, which cost $20.65.

From the valve box for Zone 5, we ran 3/4 inch PVC back to the Iris bed and to the Herb bed.

Since this was only 3/4 inch PVC, it was more flexible and we were able to use standard couplings.

Update, May 2017.  The joint at the bottom of the vertical gave way sometime this month and leaked enormous amounts of water.  Eventually, the water worked its way to the surface and I shut the main irrigation supply line off, dug down and found the problem.  I then replaced the bottom elbow fitting (and several other adjacent pieces) to fix the problem.

But it really did a number on our water usage.  Here's the water usage for the past year, from the May bill.

Normally, our usage would be about 4000 gallons; because of the leak we used over 20,000 gallons.