Irrigation Revision Project
July 2004, taking advantage of the $1.00 per square foot rebate program offered by the Las Vagas Valley Water District, we converted 8,500 square feet of lawn to desert landscaping. While the total cost was over $11,000, the reduced water usage plus eliminating the lawn service quickly covered the difference.
Our summer water usage to keep the lawn green had escalated to over 3,000 gallons a day (yes, I did check to make sure that the water meter was accurate!). To remove the lawn, they used a sod-cutter to roll up strips of lawn. Even though we had made an extra thourough watering the to help cutting, the roots just an inch under the grass were bone dry.
The installation was done as recommended by the Water District - 1/2" flexible tubing was run from the valve systems out to varios parts of the yard to from the zones. Drip lines (1/4") were put at each planting by inserting a barb into the flex pipe. The pipe was covered with sand. The sand and drip lines were covered with landscape cloth. The landscape cloth was covered with rock - 3/4" in the front yard and 1/2" in the back yard.
The Irrigation Revision project began in earnest September 2014 when after fixing several leaks earlier in the year, we had a large water bill. We discovered that (of the then 9 zones) one zone (now C2 Zone2 China Berry) was operating at 10 gallons per minute and another zone (now C1 Zone 5 Shoestring Acacia) was operating at 9 gallons per minute. In the back yard, the original sytem had thin-wall (schedule 200) pipe that was cracking (there had been several repairs. And in the front yard, the desert lanscaping had been installed in July 2004 using 1/2" black flexible irrigation pipe, which was now splitting along what appears to be a manufacturing seam. The above leaks combined with (what is now C1 Z1 Peripheral) having five repairs in the one zone drove the decision to remove all existing pipes and replace them with Schedule 40 (heavy-wall) PVC.
By a slight margin, the Back Yard East Side was selected for the first excavaions. This area is about 18" deep fine crushed rock that forms a "french drain" for the rain flow from the house, and then the pony wall with plantings. The "fun" of digging in this rock is that the width at the surface has to be wider than the depth you are attempting to reach. And along the pony wall, the roots from a palm tree have crushed against the pony wall from the back side - enough root has to be cleared to install new pipe The old pipe has been crushed by the roots. With amazing foresight, the old irrigation lines ran directly from the valves to the pony wall, and the China Berry tree was planted directly over the pipe. So the roots of the China Berry tree had crushed the pipe - therefore the 10 gallon per minute water flow when that zone was activated. Because it is planted in the "french drain", there is no good way to make a water circle for the tree, so I decided that since the tree liked that old pipe so much, I would leave that small section in place, make it its own zone, and control the water flow rate (and associated time) to get the right amount of water to the tree. Along the pony wall got new Sched 40 PVC, but the feed to the three planting islands (now C2 Zone 4) was not replaced under the concrete curbs. A 40 PSI pressure regulator was added to reduce the chance of damage from line surges. The electrical control cable for the three valves runs in-ground to the valve-box for the front yard west and then through conduit into the garage. The water feed continues to the anti-backflow valve that goes to the pool auto-fill.
Back Yard Zone 1: The feed from the first valve detours South around the tree, down under the pony wall and up to a T on the West side of the pony wall. Lines run from the T South to the gate-wall and North to almost the hedge (Zone 3 starts at the hedge).
Back Yard Zone 2: The feed from the second valve heads North a couple of feet then goes underground to the old line (entangled in the tree roots). There is one distribution manifold next to the tree that is used for drip lines to the potted plants. If the time/pressure is incorrect for the pots, the mainfold can be swapped to the capped riser on the line to Zone 4. The second valve can be adjusted for flow rate - you'll need to watch the dial on the water meter at the street - try for about one gallon per minute, then set the controller (C2 Z2) for the number of gallons per day for the tree.
Back Yard Zone 3: The feed from the third valve heads North, jogs East a foot, continues North to the path around the pool, heads diagonally North West with risers at the hedges, goes under the pony wall and up to a T. Lines run from the T South a few feet, North and around to the North pony wall. There is still a few short section of schedule 200 in this branch.