Sub-surface Drip Irrigation

Sub-surface drip irrigation continues to become an increasingly popular method of irrigating just about any landscape, from large expanses of turf to street medians to narrow planting beds.

Like standard drip irrigation, sub-surface drip uses less water, promotes healthy plant growth, is unaffected by wind and offers more uniform watering. According to Christine Canepa, senior product manager for Rain Bird’s Landscape Drip Division, because sub-surface drip irrigation takes place below ground level, it also eliminates wasteful and sometimes damaging overspray and is virtually unaffected by evaporation. “All in all, sub-surface drip can be up to 90 percent more efficient than overhead irrigation and use 70 percent less water,” said Canepa. “And because watering takes place underground, people and pets can continue to use the landscape as it is being watered, allowing for more activity in places such as parks or sports fields.”

Mike Garcia, owner of Enviroscape LA, Redondo Beach, Calif., has been installing sub-surface drip for many years. “Southern California is basically a desert,” said Garcia. “Our Metropolitan Water District imports 1.5 billion gallons of water each day, and the cost of that water continues to rise.”

Garcia said that those higher water costs have caused many of his customers to consider sub-surface drip irrigation for the first time. “Nowadays, people only seem to spend money when they know they will receive a return on their investment,” Garcia explained. “The benefits of sub-surface drip make it an easy sell in that respect. It may require an investment up front, but it will bring in positive returns for many years.”

One hurdle that Garcia initially encountered when selling sub-surface drip irrigation is the issue of root intrusion. In the past, some contractors installed fertigation units with sub-surface drip systems and pumped herbicide through it to keep roots from infiltrating the drip tubing. However, more consumers are now aware of the potential harm that synthetic herbicides can cause, making that method far less acceptable. As a result, Garcia turned to Rain Bird’s XFS Sub-surface Dripline with Copper Shield Technology. Winner of an Irrigation Association Best New Product Award in 2010, XFS Sub-surface Dripline uses copper, a natural metal, to successfully inhibit root intrusion rather than chemicals.

“XFS Sub-surface Dripline has made it far easier to sell sub-surface drip to my customers,” said Garcia. “Even after explaining the benefits of this type of drip irrigation and Rain Bird’s special technology, people will sometimes say, ‘Copper, really?’ I tell them to consider what type of pipe supplies water to your home — it’s usually copper, right? That puts it into perspective for them.”

Combine the benefits of sub-surface drip irrigation with recent technological improvements, and it’s easy to see why it’s become so popular. However, it does require contractors to take special care during installation, as well as regular maintenance. Garcia offered some tips from his own years of experience. “Because dripline is basically plastic with tiny pinholes throughout, there’s air inside of it,” he said. “When water pushes into the system and encounters air, you need an air release valve to let that air out. Otherwise, the repetitive force within the system may cause it to fail within two to three years.”

Similarly, it is important to install a pressure regulating device on a sub-surface drip system, or there could be consequences. “Under high pressure, insert fittings can easily pop off,” said Garcia. “The pressure regulator prevents that from happening, reducing the need for future maintenance.”

Also, every sub-surface drip system needs a flush, or clean-out, valve. Any debris in the system will collect at the end of the line. “By installing a flush valve, contractors can open up the valve to flush that debris away, keeping it from building up and damaging the system,” added Garcia.

Perhaps it goes without saying that it’s absolutely imperative for contractors to read the manufacturer’s instructions thoroughly before installing a sub-surface drip system. “Every product is different,” Garcia said. “I’ve seen contractors neglect to install very important system components because they tried to save time by not reading the manual. Instead, they wasted time and ended up losing customers when the system malfunctioned.”

Rain Bird offers the following tips for design, installation and maintenance success:

Keep all driplines, headers (manifolds), and mainline piping free of dirt during installation, because any contamination in these lines could plug the dripline emitters.
Check headers (manifolds) and dripline laterals for leaks before covering with soil.
Check pressure at the site and be sure to operate below the maximum rated pressure of 60 PSI (4.14 bar). Check and record pressure at the supply header and flush header. Any changes in pressure can be used in future troubleshooting.
If core aeration is expected to be done in the turf where sub-surface dripline is installed, be sure the tine depth is less than the depth of the buried dripline. Depth of dripline is recommended to be 6 inches while tine depth should not be set greater than 4 inches.
When using machinery for the installation:
– Do not drive over the dripline; always keep a layer of soil between the dripline and machinery tires.
– To help keep driplines in place, drive in the same direction as the dripline, not across the lines.
– Avoid driving in the same places at the site or you will be creating heavily compacted areas.
Be sure there is uniform soil compaction all over the site after installation.
After installation, open the flush valves (one at a time) and collect some of the water to be sure that the installation is clean.
After installation and backfill, observe the first wetting pattern. Rapid puddling could indicate a leak or might mean that the driplines are not buried at the specified depth.

“With proper installation and maintenance, a sub-surface drip irrigation system can provide years of worry-free performance while using less water than any other irrigation method,” said Canepa.

According to Garcia, in addition to saving significant amounts of water, it provides contractors with an excellent opportunity to grow their businesses by upgrading their customers to a more water-efficient irrigation method.

“I tell other contractors that one of the best ways to keep afloat in this economy is to install sub-surface drip irrigation,” said Garcia.

To watch videos about sub-surface drip installation, visit Rain Bird’s YouTube Channel at www.youtube.com/users/rainbirdcorp

Article provided by Rain Bird. Photo provided by Mike Garcia.