Roadside Irrigation: Do You Have What It Takes
The evolution of roadside irrigation equipment has progressed by leaps and bounds in the last few decades. Are you reaping the benefits of modern high-tech equipment to achieve the age-old goals of delivering the right amount of water while lowering costs, preventing runoff, and preserving water?
"We'd love to do some work in roadside irrigation, but there's no roadside irrigation done up here. We're dry enough that we could use it, but the population base doesn't apparently warrant sprucing up the roadsides," laments Dick Meyer of Scotts Bluff Landscaping in Scotts Bluff, NE.
With an annual rainfall of about 13 in., Nebraska's panhandle seems prime territory for roadside irrigation. Other states with similar rainfall levels, such as Hawaii, California, and Florida, manage to keep their highways green and flowering. But as Meyer points out, a crucial element in the equation is people---people moving into newly developing housing subdivisions, people on their way to amusement parks, millions of people moving from here to there in states that have a reputation for verdant vegetation.
As Jim Smith, highway maintenance lead worker for District 6 of the California Department of Transportation (Caltrans) observes, highway landscaping has evolved over the past 30 years: roadside irrigation has changed from labor-intensive to technology-driven. Irrigation experts at California State University at Fresno, located in a part of the state where everything from roadside vegetation to farm crops requires some amount of artificially delivered water, predict even more sophisticated irrigation technology as water becomes more expensive and federal and local erosion and sediment controls become more detailed and far-reaching.
"Twenty years ago," recalls Smith, "we didn't worry about runoff from roads. Today we know more. As we know more, we need to do better, and as technology advances, we're able to do a better and better job. Years ago we used quick couplers---you'd go out and set a line, turn the water on and let it run, then you'd do the same thing someplace else. Next the industry came up with electrical-mechanical irrigation clocks. Now we'd just set the clock. With this, the maintenance man's job changed. It wasn't that he was freed; he had to be a better maintenance person to be able to pinpoint and correct deficiencies in the new systems. The next step was digital controllers, which provided more control and offered more options. With today's technology, the landscape maintenance worker is much more advanced than his counterpart 20 years ago."
What Smith doesn't mention is that although more efficient, irrigation technology has also become more expensive. Installations are easier to use and may be less costly to maintain in the long run, but the bells and whistles that keep them humming often require a larger up-front investment. Luckily, where state and federal budgets have become less tolerant of frills, private industry---in the form of land developers who profit from new and existing highways---has stepped in to supply the impetus and capital for roadside improvements. The influx of private money has helped boost utilization of computerized flow-control programs that provide managers with better ways to deliver optimum amounts of water where it's needed and monitor systems for breaks and leaks, thus cutting costs where they can most easily get out of hand---in the water itself.
Solar Control: Doing What Comes Naturally
On the Hawaiian island of Oahu, Richard Brownlie of Brownlie & Lee in Honolulu solved his roadside irrigation challenges with solar controllers. In an area of poor soil regularly buffeted by 20- to 30-mph winds, where rainfall typically averages 10 in. a year and water rationing is a way of life, Brownlie had his work cut out for him. The original plan called for landscaping both sides and the median of a neglected stretch of existing roadway. Because the road now connects an area of new residential subdivisions with an interstate highway, demand grew to beautify the corridor, which had never been planted or irrigated.
"The state asked us to design something that didn't require irrigation," Brownlie explains. "But with the combination of soil, wind, and rainfall, we didn't think that absolutely no irrigation was a realistic way to go. We ended up using low-water-requiring plants. Additionally, because in the summer there are often mandates to cut back on irrigation watering, we staged the irrigation so we could maintain the shrub and tree plants with bubblers. Even this was a challenge because we ended up doing spray heads for the groundcover and lawn areas and going to low-flow bubblers for the shrub planting. Our design concept was to be able to eliminate or cut back drastically on the irrigation on the grass and groundcover when there was rationing---even to the point of having to sacrifice plant material if necessary through an extended dry period---while still being able to maintain the framework of the landscaping by keeping water on the trees and shrubs."
Complicating the problem were federal requirements restricting trees to a caliper less than 6 in., based on the theory that anything larger wouldn't break away easily in the case of a direct hit by an automobile. Because vegetation that Brownlie would have normally selected for such a difficult area didn't fit the federal standards, he improvised with a hedge. "We planned a hedge in the center of the median to serve a dual purpose: to beautify the corridor and to act as a windbreak. Besides benefiting the planting on its leeward side, the hedge also helped protect the sprinklers."
Because it later turned out that funding wasn't adequate to cover the required irrigation system and supplement the poor soil, the roadsides were eliminated and the project was confined to the medians---28-ft.-wide stretches that gradually narrowed at intersections to 10-12 ft. with concrete or asphalt in the nose. The hope was that once the medians were completed, either the local community or real estate companies developing subdivisions in the area would take on the roadsides. (The strategy worked, and Brownlie is now working with one of the developers to extend the project.)
To conserve as much water as possible, Brownlie's design called for supplying the spray heads with pressure-compensating disks along with the bubbler heads. The spray heads included Rain Bird's 1804 and 1812 SAMs with the PRS feature, as well as a check valve in the bottom of the head. "Although the area was pretty flat," Brownlie explains, "the benefit was that we wouldn't have any low-head drainage, which would further conserve water. In some areas, the median is a little wider, so we went to the Rain Bird T-12 and T-14, also with SAM heads. Essentially what we ended up with were spray heads at the transition areas and rotor heads where the medians narrow down to an intersection, with a single row of heads along each edge of pavement. Because the budget wouldn't allow us to do continuous groundcover planting, on the open lawn areas where we had grass from one side of the median to the other, we went to the rotor heads. Wherever we had the groundcover planting---like the hedge planting that we planted down the center, essentially splitting the median in half---we switched to spray heads, providing bubbler heads for the hedge material in case we had to cut back because of water rationing. These heads we separated on different valves from the adjacent tree planting. The result was that each type of tree has its own circuit and each type of plant material has it own circuit. This design allowed us to tailor the water to the demands of the individual types of plant."
To run all of this, Brownlie chose the Altec LEIT 4000 and 8000 solar controllers, available in four-, eight-, and 12-station configurations, all of which were used in the project. The solar controllers were chosen to avoid trenching across the existing roadway in heavy traffic. With the option of battery or solar power, Brownlie chose the solar units because he's found them more reliable than battery units. "The state's preference is to go with solar," explains Brownlie. "They're also pushing for experimentation with battery-operated controllers because they thought that might be more reliable. But our experience over the last 20 years indicates that battery-powered controllers tend to be pretty short-lived. Usually there's corrosion; the valve boxes get flooded, and typically the controllers give out after a few months. Weighing all this along with the fact that we knew the state was obviously hoping the controllers would last for years and that we realized the expediency of state crews having to change batteries every few months, we decided to go with the solar.
"Typically we ended up with two or three 12-station controllers between each intersection. That way we didn't have to cross any intersections or deal with cutting cables. The Altec LEIT controller has an option for a rain sensor-the Mini-Click 502-C-which is pole-mounted and ties in to the closest valve circuit adjacent to the rain sensor. Usually we put one rain sensor at each controller location and then tried to position them so they wouldn't be blocked by the canopy trees." The system is now being installed. Although it will eventually be run on reclaimed water, which is likely to ease the tight water situation, this initial stretch will be installed using municipal water.
Centralizing Highway Flow Control
Computerized flow control is among the arsenal of essential technologies that Caltrans has come to rely on. Caltrans District 5 landscape lead worker Stan Rodriguez describes his primary job as keeping costs down and conserving water in an area where lush landscaping is the norm but water is typically scarce. "Our primary goals are to safeguard the public (automobile drivers) and enhance the safety and productivity of the workers who maintain and troubleshoot the irrigation systems," says Rodriguez. He uses Rain Bird's Maxicom2 computerized system to put the water where he wants it when he wants it and to monitor the breaks and sprinkler-head losses that are chronic along this 12-mi. stretch of State Highway 101, the coastal route that goes through the city of Santa Barbara. Vegetation, from groundcover to ornamental plants and shrubs, is planted along both sides of the highway and in the median. In some places, each item of vegetation has own individual sprinkler or bubbler.
"We're constantly troubleshooting our systems," says Rodriguez. "We've had guardrail contractors come in and cut through our cables, override drains, and cut wires. This stretch is critical because if there's a broken head, the water goes right into the number-one and number-two lanes. We used to have call-outs every day along there from accidents and cars damaging heads. It got so bad that it was suggested the best thing we could do was shut down the system."
Instead, Caltrans changed sprinkler heads and installed centralized flow management, first with Maxicom's DOS-based system, now with the new Windows-powered version. "We program the watering schedules into the computer, and the computer automatically sends out the programs to central control cluster units (CCUs). These in turn contact each satellite or stand-alone controller. The CCU constantly monitors the flow, based on our valve database, which is the number of gallons a minute each valve is supposed to put out. As part of our data entry, we include a certain percentage of acceptable overrun. Once the flow goes over that percentage, let's say 5 or 10 percent, the computer runs a search in the Eliminate Excess Flow program, which will automatically detect and shut off a valve running beyond the programmed percent.
"If the valve continues to run or if there's a break in the line, the program switches to detecting a main-line break and will shut down a master valve right off the point of connection. This shuts down the entire site. Then the program gives you an alarm on the computer. It will tell you, for example, that you have a channel-20 main-line break, or a break at station 13 on channel 20. We then can check that location." Rodriguez is particularly enthusiastic about the feature that allows him to input the landscape architect's plans for an area, an additional aid in locating problems or breaks.
Another feature that Rodriguez says makes his life easier is the capacity to operate the system by remote control. Not only can a worker in the field access the main computer through a phone line, but there are 18 remote-control stations on-site, allowing irrigation technicians to activate and deactivate valves from a distance, which shortens worker exposure and maximizes worker efficiency. "Previously we had to shut off the valve, fix the head, and turn it back on to check what we'd done. Now, instead of getting off the highway, going back around, parking in the median, turning off the valve, doing the repair, coming around and turning the heads back on, we can do it remotely."
To help protect against leaks from severed sprinkler heads, Caltrans also changed risers and heads on sprinklers in this stretch of the system when it found that glue holding heads to the tubing had failed. Rodriguez estimates that at one site alone, crews installed between 400 and 600 new Cantex Schedule 80 0.5-in. risers, a move that cut maintenance down to almost zero. In the 8 mi. that the system uses reclaimed water, crews have replaced brass valves with dirty-water plastic valves.
District 5's Maxicom2 is hooked up to the California Irrigation Management Information System Weather Station and automatically adjusts irrigation flow to evapotranspiration rates (ET). "In this area, replacing plants is not in the budget unless there's an accident," says Rodriguez, "so we want to keep what we have while still saving water. If the system is programmed to run for 10 minutes, but the weather has been cool and we didn't lose much moisture to ET, it will automatically compensate in the amount of flow it authorizes. You can also input soil structure and precipitation rates for different heads and the system will also automatically compensate for these in the flow."
Rodriguez says Maxicom2 will be required for any new irrigation installed in the Santa Barbara area. The system is also used in other Caltrans districts.
In mid-California District 7, Caltrans installed custom-designed flow controllers along State Highway 99 through the city of Fresno. Although vegetation planted on open stretches of highway must rely on natural water, more elaborate installations at the entrances to cities and towns require irrigation. To meet this need, Mike McWhor, manufacturing manager for Buckner by Storm in Fresno, customized a controller to Caltrans' specifications. "When you're dealing with most freeway systems where the roadway is sunk into the ground and there are slopes on either side, you need a whole different type of irrigation," McWhor explains. "You really can't just put in a basic control system because there are too many liabilities. If you have a head stick on or a valve break, you could wash the entire hillside onto the road. It is a totally different type of irrigation, and it takes a different control system."
McWhor says the customized Ultima control system he designed for Caltrans was based initially on the requirement that the control system measure flow and link units together using a personal computer. "We designed a system to actually have a minimum and maximum flow on each valve, a flow that also utilized ET values incorporated from the local weather station," he explains. "We also upgraded the original system so they could page a maintenance worker in the field. The result was that they could identify the problem pretty much right down to the individual head. If it blew off a sprinkler head, the system would fire off an alarm, page whoever was in the area, and tell him what the problem was so he'd know where to go and how to fix it." McWhor estimates the first stage of the project, which he designed, utilized 33 controllers ranging from 12 to 42 stations. Since then, the corporation that manufactured Ultima has reorganized. Caltrans has continued to buy the Ultima controllers from the new manufacturer, and McWhor says Buckner plans to introduce an advanced system that has many of the features he designed into Caltran's original custom Ultima.
A Thirsty City Needs Water
In Weston, southern Florida, an entire city is being constructed by Arvida-J&B Partners of Boca Raton. The 18,000-ac. multiuse project will eventually be home to 60,000 people and will include commercial spaces and residential services. The project, which is 5 mi. across and includes a number of microclimates, is located north of Miami Beach and south of West Palm Beach, immediately adjacent to the Florida Everglades. To give the new city immediate credibility, the developers designed and installed all the landscaping in the commercial and residential areas to coordinate with completion of project phases, as well as all feeder and interior roads. Brad Walker, land development superintendent, estimates that so far the company has installed 100 mi. of main-line irrigation pipe.
"An Arvida community prides itself on its landscaping," says Walker. "What we've done here irrigation-wise is not really that different from anywhere else. It's a designed irrigation system with 100 percent coverage; it's the same kind of irrigation I've seen in Colorado and other places. But Weston is a special place based on its size."
To bring the project's irrigation system down to a manageable size, the developers chose central flow control. "With a project of this size, you have to go to central control," Walker emphasizes. "It saves manpower, it saves energy, and it saves water. I'd hate to see the manpower we'd otherwise have to have."
The developers opted for Rain Bird's Maxicom2 centralized flow control, run on a central PC in conjunction with weather-station input. "In 1983 the project was small enough that we could run it on three or four clocks," says Walker. "We simply used manpower to go out and turn the clocks on and off. Now that we're working on 12 sites throughout the project and with our sporadic rain---we can have rain on one side of the street and no rain on the other---we need more precise control. We've worked on smaller, cheaper irrigation controllers, but what we like with Maxicom2 is the ability to input a map that we can use to keep track of exactly what we're irrigating. We're more linear than round when it comes to our sites because of the roadways. The program gives us the ability to zoom in and out and to see what we're doing."
Another benefit Walker likes about central control is that he can communicate with the system through phone lines. "We can run anything anywhere from any location by telephone. When we first started with, say, 10 clocks, by the time someone drove around the project, he could kill half a day. Now I can shut down the whole project in two minutes. I don't know how I would do it without central control. It's great for Fourth of July parades and that kind of thing."
Weston's system has variable-frequency-drive pump stations that pump only as much water as required by vegetation type, saving not only water but also energy. Furthermore, instead of guessing the amount of water that should be delivered within a given time period, input from the weather station allows the system to calculate water demand on the basis of ET rates.
Much of Weston's irrigated area is covered with turf, mostly thirsty St. Augustine's grass. Medians and roadsides are planted in turf, except where the roadways lead directly into an entrance of a subdivision. Walker says central control gives him the versatility he needs in this kind of a situation. "Typically we irrigate in 1,200-foot zones. We'll put in a zone to break out a subdivision entrance, for example, where we want to water annuals and not just grass. And once the grass along the road and in the median is established, we can cut back in that zone. We typically run about 800-gallon-a-minute pump stations, which are scattered throughout the project. Or we'll run certain areas on certain satellites four or five times a week. Other areas that don't require as much water but are on the same satellite, we'll run two or three times a week."
The system allows the operator to monitor individual heads and lines for breaks and other problems that Walker says are all too common. "With construction, lawn mowers, and car traffic, problems happen all the time. When you're talking in the vicinity of 2,000 valves and 33 heads per valve on a rotor, that's a lot of system to keep track of."
Walker says that while he's satisfied with central flow control, he's always looking for new, better ways to do things. "We've standardized the project as much as we could, given the changes in technology that have occurred since we started. Over the years, we've tried to keep the heads the same. We always install 2-in. brass valves. We use drip when we have to; on narrow green spaces particularly. At the time this project was started, we were using rotors with a 2.5- to 3-inch pop. With Rain Bird, we developed a rotor of 4.5 inches, which is our recommended turf cut height. This way we're not constantly raising heads.
"We tried 6,000 feet of drip on solar control on one roadway for a while to get it established, and we found the drip wasn't durable for that kind of use. We tried it because the department of transportation wanted us to keep the water off the roads, but it became a maintenance nightmare. With weed eaters and edgers and things like that, it just doesn't hold up. Then we had some fires and the tubing melted. Finally, when the subdivision's management company took over maintenance, someone ran an edger against the beds and cut the spaghetti tubing all the way across. We went back to mist heads."
Walker says that right now what he'd like to see is a less expensive weather station and a better reading on how much weather input is required for a project of Weston's size. He adds that while weather stations are expensive at $8,000 apiece, in his experience, the expense has been worth it in the amount of water the project has saved.
Walker says he expects Weston to be an irrigation proving ground that will help standardize the company's irrigation protocol for future developments. When Weston is completed, he plans to review all equipment and procedures to determine what works and what doesn't-Walker's Irrigation 101. His wish list? Smarter controllers and probably mini PCs in the field. What's ahead? Tougher water management requirements.
So What Else Is New?
As irrigation controls become more complicated, so do delivery systems. Ken Bayne of Canaan Industries in Dothan, AL, is looking forward to equipping his roadside herbicide spraying trucks with global positioning systems (GPS). "All the information on the route will be programmed in, so the operator is essentially taken out of the loop at various points, depending on how critical you want to get. GPS will be a great help for herbicide agencies from the liability angle. If someone accuses the operator of killing his front lawn, all the agency has to do is look up the record for those coordinates for that day and it can tell whether or not its booms were spraying at that location."
From NIBCO in Fresno, CA, comes an aboveground irrigation system designed to soak, rather than spray, what its developers call a "microflood." According to David Zoldoske, director for the Center for Irrigation Technology (CIT) at Cal State University Fresno, which conducted the premarket testing, the Turf Bubbler Wick Irrigation is designed primarily for turf areas. The system uses 0.25-in. black poly tubing installed just below mowing height spaced at 5-ft. centers. The flow is approximately 22 gal./hr. "What you essentially do is flood a 25-square-foot area," Zoldoske explains. "You overcome the infiltration rate of the soil by applying water faster than it can take it up. The advantage is that the system has very high uniformity---higher than spray heads in some cases---and you don't have the vandalism problem because, although the water bubbles up above the surface, the delivery system isn't visible. The other advantage is that you can drive right over it."
The Turf Bubbler system is also low-pressure. Instead of running the 35 or 40 gal. typical of a spray-head system, the wick system operates closer to 18 or 19 gal., resulting in a reduction of energy and water. One particular advantage is that because the system is placed at 5-ft. centers, it works well in areas where turf abuts hardscape. The design is such that the first row is actually installed 2.5 ft. out from the hardscape, eliminating spray and hardscape flooding.
Zoldoske notes that installation usually costs more because the system requires more trenching than spray systems, and it has a learning curve. "You need a minimum duration of time (35 to 40 minutes) to get water to flow completely and fill in the circles," Zoldoske explains. "So you might not be able to irrigate every day; it might be every second or third day, depending on the size. If you were to run it 10 minutes a day as you would a conventional system, what you'd have is a bunch of little green circles."
Ed Norum, consultant to CIT, thinks the wick system is tailor-made for roadside vegetation but warns that unless the area to be irrigated is absolutely flat, there must be grass or some significant thatch for it to work properly. "It doesn't work on bare ground, especially if it's bare ground on a slope," he warns. "The groundcover doesn't have to be sod, it can be grass, as long as there is some kind of impedance. The system is well suited for turf areas in median strips, and it has been wonderful around motels and things where you have a little strip 5 or 10 feet across and you can't figure out any other way to irrigate it without throwing water all over the place."
From the Whetstone Group International in Escondido, CA, comes the $2 Slam Shut valve that guarantees individual head shutoff. "Someone can steal a head, break a head, or break a riser, and it will shut off immediately-guaranteed," says Whetstone's Joe Brown. "The beauty of it is that this shuts off only one head at a time, not a whole zone. The valve screws into a threaded tee or elbow, part of the irrigation lateral. The riser is then screwed into the T; the retaining rod is inserted in the riser and pivots on the lower end of the valve body. The cap is fitted on the retaining rod, and the sprinkler screwed on top of the riser. If the sprinkler is lost to theft or accident, the failure of the riser disengages the retaining rod from the dart, and the valve shuts off the flow. When the system repressurizes, the dart again engages the seat, shutting off the flow, at which point the valve is configured to produce a fine spray-what the company calls a Leak Flag. This keeps surrounding vegetation damp and draws maintenance personnel to the problem. "You don't have to replace it," says Brown. "Guaranteed 100 percent, you're never going to have to deal with this product again."
Brown says the system has had great success where vandalism is a particular problem; on Central American banana plantations, for example, where sprinkler head theft is epidemic, and in public parks in Texas for the same reason.
Disney Does It Best
From California, where irrigation is a way of life and landscape designers think big, comes a project that illustrates the cooperation between the public and private sectors that is likely to be the norm in the future. A large-scale effort by Disneyland, which is expanding its amusement park facilities, and the City of Anaheim has resulted in the redesign and beautification of a major cross-town artery to speed access directly to the new park and other public attractions such as the Anaheim Convention Center. According to Stephen Guise, vice president of sports facilities for Marina Landscape in Anaheim, which installed the initial phase of the roadside landscaping, the project required two primary irrigation sources: a Netafim Techline subsurface system to irrigate the median and roadsides and a conventional drip system for vegetation planted in the cells of an adjacent retaining wall. The median strip is 8 ft. wide, constructed 8-10 in. off the roadway, and roadside vegetation is 4-5 ft. wide. The retaining wall runs along the front of an adjacent strawberry field, a remnant of the farms that once covered the area. Landscaping consists of trees, ornamental plants, and groundcover.
The underground irrigation system was chosen for a number of practical and aesthetic reasons. "There is no spray at all," says Guise. "No cars or pedestrians are going to get wet, there will be no water overflow into the roadway, and there are no evaporation issues. Since temperatures can rise to 100 degrees Fahrenheit or better during summer months, this was important." Guise also explains that water conservation, eliminating spray, and damage to sprinkler heads from heavy pedestrian and automobile traffic were also considerations. The Techline system consists of 17-mm-diameter, flexible plastic tubing with emitters spaced every 12 in. The tubing was installed in rows 18-20 in. wide. Flow can be set for 0.4, 0.6, or 0.9 gal./hr.; the pressure compensating range runs from 7 to 70 psi, with a maximum pressure of 45 psi. The system is self-flushing during the entire watering cycle and has a root barrier that helps prevent root intrusion. Blank tubing is available for special applications, and Techline is also available in purple for reclaimed water.
Guise points out that another feature of subterranean irrigation is maintenance-no broken sprinkler heads to fix. "It's flexible plastic pipe, not rubberized hose," he emphasizes. "The emitters soak the soil, and this must be correctly blended to cause wicking up rather than down. For this reason it's extremely important to have clays and silt in your soil mix, especially if the native soil is sandy."
The drip system for the retaining wall was installed off a 0.5-in. surface main line, with a dripometer and individual lines running directly to each plant. "When you have a cell system, it's extremely important to have water running to each plant," says Guise. "You can't drip from the back of the wall because then you have the problem of the water getting behind the wall and causing a blowup."
Guise has used the Techline system in a polo field in Texas and at the Oklahoma City (OK) Memorial Park. "There we used a specialized designed of the Netafim system with reinforced mesh above it. The way the memorial is designed---a stark background with bronze and glass chairs for each victim---it was very important not to have any clutter on the surface." His only word of caution about the Techline system is the importance of the soil mix. "When you're dealing with systems that are flooding from the bottom up, it's extremely important to be concerned about the soil above it. You must have a wicking action."
And so a lot of things have changed, and nothing has changed. The rationale of roadside irrigation remains as it has always been, delivering the correct amount of water to vegetation. But the delivery systems are changing, allowing landscape architects to design more elaborate installations and highway departments to revitalize older projects with better control, lower overall costs, and less maintenance. The tradeoff, as roadway irrigation veteran Jim Smith points out, is that the new systems are often more complicated to install and manage. But with new regulations and increased demand for water conservation, computer---controlled subterranean delivery systems, valves that shut themselves off, and low-profile heads are likely to be what it takes for effective roadside irrigation-now and in the future.
Author's Bio: Journalist Penelope Grenoble is a frequent contributor to Forester Media, Inc. publications.