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THE HANDYMAN : Tired of Hauling Hose? Maybe It's Time for a Sprinkler System

April 29, 1989|JOHN O'DELL | Times Staff Writer

Spring in Southern California, while a season of overcast mornings, is the time to start aggressively watering and feeding lawns and shrubbery to get them ready for the heat of summer.

It's also a good time to consider a permanent sprinkler system.

While installing an in-ground system can seem daunting, there really is nothing to it.

Dale Rahn knows--he's in the midst of putting in the third in-ground sprinkler system since he and his wife, Suzanne, moved into their 1930 Spanish revival home in Orange's Old Towne 9 years ago.

Dale--the vice president of a wholesale nursery company and the holder of a degree in ornamental horticulture and a certificate in landscape architecture--was undaunted by the ill-kempt back yard.

"It was wall-to-wall weeds, 3 feet tall," he recalls. But Dale put his training to work and put in a small lawn, a large garden and a tiny orchard, all serviced by an in-ground sprinkler system.

A year later, the Rahns' first child, Lauren, now 7, was born. Emily followed 2 1/2 years later and the layout of that pre-child yard soon stopped working.

It took a while to get started, but earlier this month, Dale finally began work on a redesigned yard that incorporates a more sophisticated landscape design.

One of his first chores, after ripping out the old landscaping, was to install a new sprinkler system. For ease of installation, and to keep costs down, Dale used PVC plastic pipe and fittings.

But he chose brass for the sprinkler heads and the all-important anti-siphon valves--a special shut-off valve required by building codes to keep water from the irrigation system from backing up into the household water lines.

Brass is tougher than plastic, so the exposed valves--which also turn the system on and off--won't become brittle in the sunlight, as plastic valves can, and the sprinkler heads will hold up better than plastic.

Rahn's system is more complex than many because of the curvature of the shrub beds that border the lawn. But for a relatively simple rectangular lawn area (you can modify the instructions for your own layout), here's how to do it:

PLANNING Draw a plan of the yard layout, making sure to include the existing water supply into which you will hook your system (usually a hose bib).

Next, plot the location of your pipe lines and sprinkler heads. Remember, the more independent lines (a separate anti-siphon valve for each) you use, and the fewer sprinklers on each line, the better your water pressure will be.

There is a wide variety of sprinkler heads on the market, and each has different characteristics, so before you decide where to put them, choose a type and follow the manufacturer's recommendations for spacing. Always space your sprinklers so there is plenty of overlap in the watering pattern. (See illustration.)

For lawns, use pop-up sprinklers--the nozzle that delivers the water pops up under pressure to clear the height of the surrounding lawn or ground cover. For shrubs, use standard fixed (non pop-up) shrub heads.

What usually works best are quarter circles in the corners and half-circles along the edges, spaced so the water patterns overlap by several feet. Fill in the center with rows of full circles.

PVC pipe comes in several different thicknesses and diameters. Most systems work best with 3/4-inch diameter pipe. Use "schedule 40" pipe for lines that will be constantly under pressure and the less expensive thin-walled "class 125" pipe for the rest of the system.

For a simple rectangular lawn 40 feet wide and 20 feet deep, using sprinkler heads with a maximum of 20 feet of coverage, you would need to install three rows of sprinklers along the 40-foot width, as illustrated. The watering patterns overlap, ensuring plenty of coverage and no dry spots.

TRENCHING After you've plotted the system and purchased the requisite pipe, fittings, valves, sprinkler heads and PVC primer and glue, it's time to dig the trenches. They should be 6 to 8 inches deep, so you won't risk cutting pipes if you later run a roto-tiller or cultivator over them. If you are using an extra-large sprinkler head, you may have to dig deeper. Check the measurement.

You can rent a trenching machine at most equipment rental yards, but a shovel works just as well. Dig your trenches as close to the edge of the lawn as possible and make sure to trench all the way up to your water connection. If you have to tunnel under a sidewalk, use a high-pressure nozzle on a hose to blast some dirt loose, then bore it out with a piece of steel pipe, blast again with water, bore with the pipe and keep repeating the process until you've drilled a hole right under the concrete.

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