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Designing With Drip

RICHARD LENTI | Drip Irrigation - Low Flow

At the new Wynn Las Vegas resort, the decision was made early on to use synthetic turf in areas where there would be high traffic. Yet the use of that synthetic turf did not eliminate the need for an irrigation system; it just altered the direction the system would take.

 

Gone is an overhead system. In its place is drip irrigation to precisely feed the thousands of plants that fill the picturesque landscape. In a desert climate like Las Vegas, the need to conserve water is obvious. So were the benefits of drip irrigation.

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Initially designed for the agriculture industry, drip irrigation can be effectively applied to any non-turf area, including shrub beds, flower gardens and hard-to-water areas. By delivering water slowly, at low pressure, to the root zone of the landscape plant material, drip irrigation wastes virtually no water.

Targeting the precise area that you want to irrigate, these systems typically operate between 15-50 psi. Their flow rates are measured in gallons/hour (GPH) versus gallons/minute (GPM), and that can result in water savings of 30 to 65 percent compared to traditional systems.

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Photo Courtesy: Netafim

Now you may not have to a job the size of the Wynn Las Vegas currently on your plate, but the watering and nutritional needs of landscape plants remain the same. And the same principals and planning that went into the resort’s irrigation system can go a long way in making your future projects a shining example of water management and efficiency. One of the best ways to achieve that efficiency is by including a drip system in all those plans whenever possible.

The obvious benefit of drip irrigation is that it saves water. By giving the landscape contractor increased control over the distribution of water, you use only the exact amount of water that’s needed for each plant being serviced by a drip emitter. Water loss due to evaporation is virtually non-existent, along with the havoc a windy day can cause on the spray patterns of overhead sprinklers.

The over-spraying of your intended targeted is also eliminated, along with the unplanned soaking of sidewalks, cars, buildings, roads and parking lots. Besides wasting water, the liability of the damage caused by runoff is a serious issue that you can’t ignore in the litigious society in which we live.

Now in a perfect world, the system we put in place would remain just as we left it. But in the real world, people often don’t leave things as they found them. Whether it’s by design or by accident, irrigation lines are often vandalized. And having to constantly repair a system, no matter how water efficient it is, can make the process seem more trouble than it’s worth. In the case of drip systems, the very nature of how they’re often installed can make them prone to accidental or intentional damage.

“Vandalism is a perceived problem on some drip systems, particularly in open areas where there’s a lot of foot traffic,” says Janet Reilly of Rain Bird, Azusa, California.
“It’s the same issues that you get even in a traditional irrigation system. People play with the rotors; they kick them.”

While the relative low costs of drip systems make them unlikely targets for thieves, because their components are often installed above ground, it makes them extremely vulnerable.

“It could be something simple like a 12-year-old kid waiting for the school bus to come and he’s kicking over sprinkler heads,” says Travis Komara of Salco Products, Fontana, California. “It’s very common just to have the drip tubing lying right on top of the ground, with the emitters near the plants exposed.”

If the system you’re designing is in an area that’s prone to foot traffic, you’re just asking for trouble by employing an above-ground installation.

“When they’re not visible or accessible, they’re not going to be vandalized,” says Komara. “If it’s a high-traffic area, you should definitely be covering the lines, and also the type of ground cover you use in these areas makes a difference. You want to use something that will give, like mulch or a jute combination. You don’t want rock ground cover because when people step on that, it will pierce the line.”

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Photo Courtesy: Salco Products

The simple act of using stakes to keep the drip lines in place will go a long way toward preventing damage. “If contractors lay out tubing,” says Rick Heenan, of DIG Irrigation, Vista, California, “don’t stake it down, and then cover it with mulch; the tubing can bow up through the mulch and become exposed. Once that happens, people can trip on the line; it can be damaged from shovels or rakes. Once it’s snagged and pulled up through the mulch, it can become a mess.”

Shielding the tubing from sunlight will also go a long way in preserving its life span. Although UV inhibitors are built into the raw materials of any good drip irrigation system, a constant sun beating down on any material will take its toll. “Usually the rating is approximately eight years above ground, but eleven years below ground,” says Heenan.

“If you can bury the drip tubing so that there’s four to six inches of dirt on top of it, and then add a layer of mulch, that’s ideal. You only have a little extension of ? inch tubing above grade that’s exposed to traffic, the sun and people standing on it.”

The key to protecting a drip system from a myriad of problems, including vandalism, begins with the installation. Drip is a wonderful, water saving approach to irrigation, when used properly, but it is not a panacea. A poorly installed drip system will save you neither time nor money.

The installation is critical,” says Reilly. “If you’re doing a shrub bed in your house and no one else is going to be around it, it’s not as critical. When there are a lot of other people around and they can have access to it, then you probably want to make sure you bury your tubing under mulch, or a few inches under the soil. You want to place the emitters as close to the plant as you can so they’re not sticking up in the middle of nowhere. And you want to use quality products that don’t break easily.”

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Photo Courtesy:Rain Bird

There are several products available designed to help make a drip irrigation system vandal-proof, whether you are using flexible tubing or PVC pipe. Some emitters can pop up and down, retracting flush with the grade when not in use, keeping them out of sight. These micro-sprays act like a pop-up sprinkler, but they dispense a low volume of water. Other products are designed to make it easy for contractors to install tubing below grade.

For commercial systems,” says Reilly, “instead of having poly-tubing all over the place, a lot of people will install PVC pipe like you would in a traditional system. Then, by using a poly-flex riser as a connection to the PVC, there will be no tubing exposed. You can actually hide the emitter in the plant so you can’t even see it. Even if the poly-flex riser is kicked, it’s very flexible. So that is a very robust system.”


Placing the system below the grade is a good start to ensuring its trouble-free operation; another is making sure the drip system is properly installed. “A common mistake is people not understanding the product,” says Komara. “Every manufacturer has accessories and installation tools that they recommend. But if you decide to use a cordless drill instead of the recommended hose punch, you won’t get the same result even if it’s the same diameter hole. A hose punch actually separates the material. The drill bit displaces material, so you won’t get the same seal. There’s a learning curve to installing the product.”

Many of the mistakes made at this stage of installation are easily remedied by a simple solution: follow the instructions provided by the manufacturer. When in doubt, call them. It certainly is in their best interest, and yours, that the job is done right the first time.

“There are characteristics to every single product installed,” says Komara. “Even if it’s not our product, I still recommend that contractors call the manufacturer or have a detailed instruction manual on how to install the product properly.”

Even after you’ve gone through the trouble to hide the tubing and emitters, along with following all the instructions, a poorly designed drip system can be as problematic as one that is constantly vandalized. “A lot of problems that we hear about,” says Komara, “are on the design side, where people don’t fully understand how to design with drip. There are some hydraulic characteristics you have to take into consideration.”

“For example, every valve is rated to close at a certain flow. If they don’t see that minimum flow, they just won’t close; they’ll stay open. And that will throw off the entire system. That’s one of the most common issues we deal with; the product wasn’t installed per plan and the system has been stretched beyond its hydraulic specifications”

To avoid these common problems, all contractors need to do is familiarize themselves with these systems, be aware of their specifications and stay within them. If you try to exceed what they are designed to do, that’s where the failure will occur.

Unlike conventional irrigation systems where it’s easy to spot if a sprinkler head is working, a drip line requires a little more attention. “Most contractors are familiar with maintaining a sprinkler system,” says Stuart Spaulding of DIG Irrigation, “where they check the heads and can visibly see them. But with a drip system, there isn’t water shooting in the air, so it has to be checked differently.” That can include flushing out the line periodically to avoid clogging the emitters.

Often all it takes is a little practice and a little common sense before you’ll start getting the hang of how to best design and install a vandal-resistant drip irrigation system that requires little maintenance. Now both you and your clients can enjoy the benefits that this innovative approach to irrigation can provide.

“The first advantage is water conservation,” says Komara, “and a more efficient use of water. Then there are other concerns. If it’s an installation in an area that has very high winds, you don’t have the wind effects that takes place when you’re using conventional sprinklers.”

Areas sensitive to overspray, and with mixed plantings are ideal candidates for landscape drip systems. They are especially efficient in areas comprised of a mix of plants and flowers. “If you’re irrigating a high traffic area, say an interiorscape at an airport, you won’t have the problems of runoff or over-watering beyond the root zone,” says Komara. “Obviously, for liability concerns, you don’t want water on marble floors in the Delta terminal at LAX.”

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Photo Courtesy: Rain Bird

Because a drip irrigation system is positioned to distribute water near the plants’ roots, it avoids the watering of soil between the plants. What that does is cut out a lot of unnecessary maintenance. Unwanted watering will cause weeds to grow; those weeds will need to be removed. That’s additional time you’re spending on a jobsite that you don’t have to.

As technology has improved, so has the world of irrigation; and certainly the part of that universe being inhabited by drip systems. We’re now seeing a more uniform manufacturing process that translates into a higher, more efficient quality of product being designed and installed.

In a time when every drop of water counts, drip irrigation should not be ignored. It is more than an invaluable part of preserving the environment; it is fast becoming an essential part of the irrigation service you could be offering to the residential and commercial clients you service. Odds are you don’t have to be designing the Wynn Las Vegas to begin enjoying those advantages.
 
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