Before I began writing for Irrigation & Green Industry, I had little knowledge of how sprinkler systems were installed, or why valves should be installed below ground instead of above, as mine were. Now that I’ve done some research on the subject, I realize the benefits of putting the valves underground.
Although some irrigation installations are still being done with valves installed above grade, however, it is more common today for the valves to be placed below ground. However, there is one more additional component to be added when installing below ground, and that is a valve box.
Why valve boxes? First and most importantly, the box secures the valve in a clean environment, and prevents damage to the wires. Additionally, if you have to service the valve, it’s easier to work on.
“Valve boxes create a serviceable environment for the valves,” says Bob Diersing, owner of RILawnsprinklers in Cleveland, Ohio.” They keep valves safe, clean, and easily maintained in a below-ground environment.”
“I’ve seen some installations where valve boxes were not used,” says Jeff Carowitz, a leading consult ant.
“When the valves needed servicing, they were very difficult to find because they were buried in the soil.”
Valve boxes are relatively easy to install and offer aesthetic value to a finished landscape. Position them in inconspicuous areas, such as shrub beds if possible.
In terms of placement, the obvious objective is to install valve boxes in areas where they will be less noticeable or hidden from view entirely, so as not to detract from the beauty of a landscape. Clearly, if you install the irrigation system before you install the landscape, it may be more difficult to identify which areas may be less conspicuous.
Once you’ve determined where you’re going to install the valves, mark the location where they are to be buried. Don’t compromise accessibility, and always mark on a drawing where the valve boxes are installed, for future reference.
Prior to installation, you should prepare a crushed rock base. “You need to establish a good firm foundation rock base that’s installed a number of inches below the grade level,” said Britt Sweet, marketing manager of Oldcastle Precast Concrete. “You need to measure, and get the level of the crushed rock. Don’t use gravel—it’s fluid, and it moves—then finish the grade level of the valve box.”
This is an important step in installation. Without the rock base, the valve box has a propensity to fill up with water and will not drain properly. “If you have a problem that requires service,” added Sweet, “you would have to go clean out the muck and bail out the water, or pump it out before you could service it.”
Using a crushed rock base provides a place for the water to go without causing a backup in water flow. It also prevents the box from sinking further into the ground due to the added weight of the water.
Also, the base provides just that: a base to prevent sinking. With the rock base, the valve will not heave or tilt or sink or settle. It will stay precisely where you installed it, at grade level, nice and smooth, the way you want to see it.
Some contractors use filter fabric to prevent soil from settling back into the box. Wrap the fabric under and around the valve box and secure it with duct tape. The tape will hold the fabric in place until you’ve completed backfilling. With the combination of gravel and filter fabric, a valve box can more easily fulfill its objective for the life of the project.
If more than one valve is going into a valve box, it’s much easier to build a manifold before it goes into the ground. Attach the nipples into both sides of all valves being installed. Using an adapter, fasten a piece of pipe between each valve, making sure it’s long enough to cut out the valve later, if necessary. Depending on the number of valves and the location of the supply line pipe, elbows are used to design the manifold so it will fit in the master valve box.
It’s always advantageous to install the box so that the lip is just above ground. The reason for this is that generally the grade is going to creep up, the soil will settle and the grass will grow around it. The growth will vary from location to location, so use your best judgment.
If you install the valve box too low, the box has a tendency to get covered over or washed over, making it extremely difficult to find, no less to access the valves. If you install it too high, it becomes a safety hazard. A protruding box that is not out of the way or next to a structure tends to be in an area of play or traffic. It becomes a tripping and falling hazard for children and adults alike. Not to mention that a box which sticks too far above the ground is unsightly.
When choosing a valve box, size really does matter. If the box is too small for the number of values, it will be nearly impossible to service. If you don’t have the hand clearance, you’ll have to dig the box out in order to work on the valves. To achieve optimal performance, choose the size in proportion to the job.
“I’ve seen some boxes with six valves inside,” said Carowitz. “And even two-tier boxes, one on top of the other, which totally defeats the purpose of having a valve box. That’s a great deal of wasted time servicing that one valve because of inadequate space.”
Bob Dobson, owner of Middletown Sprinkler Company, Port Monmouth, New Jersey, says that, on larger projects, labeling valve boxes saves hours a year in maintenance cost. “Labeling each valve box with a station and zone number makes it easier to find when there is a problem, especially on very large projects such as retirement communities, where you can easily have 500 to 800 valve boxes installed.” Dobson continues. “We place the valve boxes in inconspicuous spots and indicate their location on the final drawing, which makes them easily accessible for maintenance and service.”
“Valve boxes are also used in specialty areas, for example, if you’re installing a fertigtion unit, you would put it in a valve box,” Carowitz adds. “Also, if you’re going to install a quick coupler (QCV), you need the accessibility; that too should go in a valve box.”
Another area where valves boxes are used is when installing a drip irrigation zone system. This system includes the valve, pressure regulators and filter. Putting them in a valve box is especially helpful when cleaning and changing the filter.”
“Irrigation valve boxes are important to use for a variety of reasons,” says Mike Kramer, The Pattie Group, Novelty, Ohio. “Additionally, they protect other parts of an irrigation system that may need service, including: wire splices, gate valves, ball valves, certain types of backflow preventers, multiple drip emitters, flush valves, air-relief valves and the like.”
Another specialty valve box is the emitter box. Manufacturers specifically designed it to cover multi-outlet drip emitters. These differ from standard boxes in that they have long slots up the sides to accommodate the quarter-inch distribution tubing that you can feed up the sides. These boxes not only protect the emitter but also help to prevent potential vandalism.
To blend in with the landscape, valve box covers are available in a variety of colors: black, green, gray, bark, tan and purple. If you’re installing a valve box in a grass area, a green cover is appropriate. It blends in with the turf. If you’re installing a box in an area with bark or mulch, a bark-colored cover works best there, and so on. Because purple is the standard.