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Central Control Irrigation Systems (C.C.I.S.'s) have been around for many years now, saving countless gallons of that precious commodity...water. Being in charge of numerous existing parks with extensive or elaborate irrigation systems, you don't have the luxury of being able to start from scratch and install a brand new system with new Points of Connections of unlimited size, new remote control valves (R.C.V's), main and lateral line piping, conductors, or even heads. You do however have the power to control the major components that will become part of your new C.C.I.S.: 1. Water Meters & Backflow Prevention Devices 2. Master Valves 3. Flow Sensors 4. Conduit & Conductors for Master Valve & Flow Sensors and 5. Satellite Controllers / Central Computers. These major components make up the "heart" & "brains" of your new C.C.I.S. You'll need to follow some or all of the following steps to make sure that your new C.C.I.S. will perform to your satisfaction. Step 1: Involve All Parties (Communication) The maintenance crews can tell you the intricacies and the overall "health" of each park's irrigation system. Foreman & Supervisors can relay this valuable knowledge to upper management and the manufacturer's rep. Each manufacturer of a C.C.I.S. has pluses and minuses that need to be evaluated before deciding upon a particular brand or manufacturers' product. Most manufacturers will provide sample controllers for field technicians to try out on actual park sites. Each park system is usually unique in nature, so a C.C.I.S. that works well with one park system may not be applicable or even feasible in your situation. Have an open mind and research each manufacturer's specifications before deciding upon which company's product you will have installed. Once you gather this important information, upper management can then get a "flavor" of what some of the costs might be once this input is received from the field, and manufacturers can figure out what components will work best for each type of situation. Step 2: Site Visits & Inspections Some cities have dozens of parks. Retrofitting these numerous parks could take several years to complete and cost tens of thousands of dollars to install, so rank each site by your own method of importance. Items such as how much water and money will be saved by using Central Control on a particular site are good items to start with. The sites that will save you the most water and money should be at the top of the list. Coming up with a list of prioritized sites will go a long way in keeping costs in control and job installations on track. Keep in mind that these savings in water and money will eventually pay for the installation costs involved in installing your C.C.I.S. In your site visits, make up a list of the five major components previously mentioned. Starting with your Point of Connection (P.O.C.), make sure that your water meter & Backflow Prevention Devices are sized properly and are up-to-date. Older meters can be out of calibration or even non-functioning. Accurate meter readings are vital for calculating precipitation rates for each hydrozone. They are also a way of checking to see if your flow sensors are within the same readings as your meters. Another thing to keep in mind is that some systems were originally designed poorly to begin with. These two items alone can have a huge impact on system performance. Just because you're installing a C.C.I.S. and other needed components doesn't mean that your existing system will perform any better once these components are installed. Actually, by installing a new Master Valve and Flow Sensor, you may be adding more dynamic losses to your original system. If your system is already on the borderline with marginal pressure, then you'll need to take the time to check your hydraulic losses and see how they may affect your system performance. A lot of older parks have either antiquated, outdated, or in some cases NO backflow prevention devices. You'll need to contact your local water purveyor to see if your system is up to code. Keep in mind too that if you have to install a new Reduced Pressure Principal Device (R.P.P.D.), you'll have an immediate dynamic pressure loss of between 8 & 13 P.S.I. Again, this amount of loss can drastically affect your system performance or may in fact cause "lack of coverage" issues with your turf rotor heads. If you already have high static pressure to begin with (80 to 120 P.S.I.), then these "incidental" pressure losses should not affect system performance. If your static pressure is in the 60 to 80 P.S.I. range, then you may have to upsize your water service, meter, and R.P.P.D. to compensate for some of these losses. An inline booster pump may also have to be installed to provide you with the needed pressures to operate your system efficiently. While inspecting your service & water meter, check to see if the water meter installed feeds both the domestic and irrigation system. If so, then you may be unnecessarily paying extra sewer reclamation fees. A lot of water purveyors now charge a "sewer reclamation tax" for all water flowing through your meter. It is assumed that all metered water being used will be reclaimed through the sewer system and recycled at the water treatment plant. For this reason, a tax is levied on all metered water regardless of the fact that the majority of water is being used for landscaped purposes and is not being recycled. If you do have a "mixed meter," you may want to see how cost effective it is to have a new dedicated landscape irrigation meter installed that will strictly meter water applied to the landscape. A dedicated landscape meter is not charged this sewer tax. Having any existing "As-Built" plans available of the irrigation system will greatly aid in your pressure design calculations and potential meter retrofit installations. You may even find that these plans show that these P.O.C. components were improperly designed to begin with. Planning ahead with this information will save you countless hours of trying to figure out why your newly installed C.C.I.S. is not performing satisfactorily. For your own peace of mind, do NOT skip this step. You'll want to decide on whether you want to use a Normally Open (N.O.) or Normally Closed (N.C.) Master Valve. Using an N.O. Master Valve, the main line will be constantly pressurized, which will allow your maintenance crews to have pressured main lines for Quick Coupler Valves (Q.C.V.'s) and hose bibs. If you have a major break in your main line, the Flow Sensor will detect too much flow in the main line and then have the controller energize the Master Valve and shut it down. Using an N.C. Master Valve, the main line will only be pressurized when the start times activate the controller to start the watering sequence. The main line will only be pressurized when the system is on. This can be a disadvantage during the day if the maintenance personnel want to use pressurized water. One advantage of using an N.C. Master Valve is that if you're watering on a sloped area and a R.C.V. sticks in the open position early in the morning, the Master Valve will shut down the entire main line once all watering has taken place in the program. This could help to eliminate any chance of water damage or flooding caused by the R.C.V. staying on for one or two days. Some, if not all of the manufacturers have a Master Valve bypass on the controller where the maintenance crew can push a couple of keys to turn on just the Master Valve to activate or pressurize the main line. Once again, before you can make these important decisions such as sizing the Master Valve and Flow Sensor, you'll need to complete some additional work to get this data. Before you can decide on the size of each item, I recommend that you take meter readings for each R.C.V. on the controller. But, before you can even complete this task, you'll need to have your irrigation technicians inspect the entire irrigation system and repair all broken pipes, misaligned, damaged, and plugged heads on each and every R.C.V. This is not only important because of how a poorly operating system can affect distribution uniformity and efficiency, but you'll need to know the accurate usage in Gallons Per Minute (G.P.M.) to aid in determining your precipitation rates for your yearly watering schedules. Also, the Flow Sensors in conjunction with the satellite controllers will automatically "learn" what the flows are for each station. If you input inaccurate data for your flow rates, then you'll be wasting both water and money in the yearly operation of your system. This system tune-up can be performed before you gather data on your site inspections. Once you gather the accurate G.P.M. data, you can then determine the size of both the Master Valve and Flow Sensor. Most parks that I've worked on generally use a 2-inch, 2 1/2-inch, or 3-inch Master Valve, depending upon the total flows being used throughout the system. If you have a lot of low flow R.C.V.'s for spray heads, drip R.C.V.'s, etc., then you may end up using 1-inch, 1 1/4-inch, 1 1/2-inch or 2-inch Flow Sensors. If most of your flows are above 25 G.P.M., then 3-inch Flow Sensors are typically used. Flow Sensor manufacturers will list the recommended size Flow Sensor for a given flow range. One more important thing to remember with your flow rates and newly installed C.C.I.S. is to keep your main line velocities at the original design specifications which is typically 5 ft./sec. Most of the new satellite controllers will allow you to operate several R.C.V.'s concurrently. If you don't know your flow rates for each R.C.V., you could "overtax" your system. This can cause you to run too high of a velocity through your main line, which in turn could cause damage to the pipe such as splitting or cracking due to water hammer. Too many G.P.M.'s flowing through the system can also cause excessive dynamic pressure losses that in turn could give you poor uniformity of your rotor heads due to low nozzle pressures. By completing the above task to gather flow data for each R.C.V., you can now pick and choose the maximum number of R.C.V.s that can operate at one time without "overtaxing" your system. Once you've decided on what type and size of Master Valve to install and what size Flow Sensor to use, it will be important to locate these components at a spot close to your P.O.C. so that you'll be tied in ahead of all downstream appurtenances such as R.C.V.s, Q.C.V.s, and hose bibs. If you tie in the Master Valve and Flow Sensor too far away, you could end up bypassing main line that could go off and feed several R.C.V.s. Bypassing these R.C.V.s would mean not being able to measure flow output with the Flow Sensor. I recommend that PVC (1 1/4 inch minimum) conduit be installed in a 12-inch deep trench with pull boxes installed every 100 feet along the conductor path from the satellite controller to the Master Valve and Flow Sensor. Keeping the trench at a 12-inch depth will help prevent a lot of unnecessary repairs to the system such as cut conductors, pipe, and plugged up nozzles due to debris inside the piping. The conduit will protect the conductors from mechanical damage caused by rodents, rocks, and digging tools, and it also speeds up the installation of the project. You can always go back and pull in the necessary conductors, even extra conductors for additional R.C.V.s, at a later date. There are several methods available for communicating from the Central Control main computer to the on-site satellite controllers. Telephone lines using modems and radio-based units are two common ways of sending data back and forth between both the Central Control main computer (usually located at the main office) and the on-site satellite. Most manufacturers offer several different ways to perform this intercommunication. Field technicians from the factory will usually visit and inspect each site separately to determine the best method of communication. During this last phase of the inspection process, you should also take solenoid readings of each R.C.V. at the existing controller terminal to make sure that all R.C.V.s read within normal operational resistances. At this time, you can also check for opens or shorts in the wiring and see if all R.C.V.s are indeed operational. It is also a great time to decide if you like the order of station operation. If not, you can retag and put all R.C.V.s in a logical order for ease of future trouble-shooting. Once tagged and placed in order, it will make the installation of the new satellite relatively easy to install. Step 3: Installation of Components You now need to decide on whether or not you want to install these components in-house or to have an outside contractor or consultant install them for you. If your crew has the necessary plumbing and electrical skills and you have enough manpower, you may want to do the work in-house, especially if your department has trenchers, backhoes, loaders, etc. available. Doing the work in-house also allows you the luxury of starting and finishing the project at your convenience. Depending upon the time of year, you can do most of the work at one time or in stages depending upon your budget, available manpower, and weather conditions. The following six stages are listed in preferential order but are by no means required to be installed in this order after your preliminary site inspection and system tune-up has been completed. As with any construction project, you're wise to call Underground Service Alert (U.S.A.) 1-800-227-2600 or any other underground locating service before beginning any type of excavation work to avoid cutting or damaging any buried utilities such as telephone, electrical, gas, and communication lines. Barricades, Caution Tape, and plywood to cover open holes should be used if needed for safety reasons. Actual park projects with photos are used for explanatory purposes throughout this article and each of the following stages: A. P.O.C. - Updated Service, Meter, and Backflow Prevention Device if needed B. Master Valve installation C. Flow Sensor installation D. Conduit & Conductor installation E. Satellite & Central Computer installation F. Final Inspection, As-Built Drawings, & Photo Documentation Installation Stage A - P.O.C. - Updated Service, Meter, and Backflow Prevention Device It was determined during the initial site visits that an excessive dynamic pressure loss of approximately 43 P.S.I. was attributed to these undersized components which didn't allow the rotor heads to operate properly. The 2-inch service and 2-inch water meter was upsized to a 4-inch service and 3-inch water meter. The two 2-inch R.P.P.D.s were up-sized to a 4-inch R.P.P.D. It was also determined during the preliminary site inspection that the domestic water to the building had a cross connection because a backflow prevention device had not been originally installed. It was also decided that separate water meters needed to be installed for both irrigation and domestic purposes to avoid paying sewer reclamation fees for the irrigation water. I recommend the use of only copper or brass pipe and fittings for 2 1/2-inch P.O.C.s and smaller. The use of cement-lined ductile iron pipe and epoxy coated cast iron fittings are recommended for 3-inch and larger P.O.C.s. PVC C900 & PVC Class 315 pipe is recommended for all piping downstream of Master Valves and Flow Sensors for 4-inch and larger tie-ins. Class 315 PVC is recommended for 3-inch and smaller tie-ins. Depending upon static pressure conditions, you may need to install a Pressure Reducing Valve before the R.P.P.D. A "Y" strainer should also be installed before all system components. Mechanical joint fittings using Megalug(TM) type restraints can greatly speed up the installation process over conventional threaded fittings and pipe. Use of solvent weld fittings on larger size P.V.C., if not properly solvent welded, has a tendency to pull apart and leak. Use of concrete thrust blocks under each joint isn't necessary if joint restraints such as Megalugs(TM) are used. However, I recommend the use of these concrete thrust blocks for support and in case any existing downstream piping uses gasketed pipe and could pull apart after pressurizing the main line. Do not use galvanized steel or unlined cast iron in any of your installations. Tuberculation can rob your system of valuable dynamic pressure. Also, depending upon your soil type, a "hot" soil can cause premature corrosion of the galvanized steel. Be sure and wrap all metallic piping below ground with 10 Mil Tape to prolong the life of the piping. Keep in mind that R.P.P.D.s have relief valves attached to them, and sometimes these relief valves open up when a device detects a pressure differential of less than 2.0 P.S.I.D. between both check valves. This relief valve can dump a large amount of water in a very short time, so be sure that the R.P.P.D. location will not cause any type of localized flooding if the relief valve happens to open up. You can install a catch basin below the relief valve and run drainage piping from the catch basin to an area designated for drainage to help prevent localized flooding around the R.P.P.D. Installation Stage B - Master Valve Installation The Master Valve should be installed directly downstream of the R.P.P.D. The top of the Master Valve should be just below the top of the valve box, and the valve box top should be flush with the finished grade. PVC Schedule 80 S x S unions should be installed before and after the Master Valve. Threaded unions have a tendency to split if over tightened and are not recommended. P.V.C. Schedule 80 nipples are screwed into each end of the Master Valve, and the end threads are then cut off and solvent welded into each union and 90-degree elbows. All P.V.C. slip fittings are primed first and then solvent welded. All joints are then wiped clean. A large valve box is then place around the Master Valve and set to grade. Installation Stage C - Flow Sensor Installation The Flow Sensor should be installed a distance of approximately 10 times the pipe diameter downstream of the Master Valve. I recommend at least 15 times if enough room is available due to the fact that excessive turbulence leaving the 90-degree elbows of the Master Valve may cause inaccurate readings of the flow sensor. More research needs to be done on the 10-times-pipe-diameter standard spacing to see if this really is enough of a straight run to avoid turbulence. Regardless, NEVER install the Flow Sensor immediately after the Master Valve. A straight run distance of 5 times the pipe diameter is recommend downstream of the Flow Sensor. In some of the photos, you'll see that a 2-inch Flow Sensor was installed to monitor low flow R.C.V.'s even though the main line size is 4 inches. Use of a smaller flow sensor and minimal length of piping will not affect dynamic flow losses or system performance even though higher than normal velocities will be experienced with the smaller piping. One important item that should also be installed downstream of the Master Valve and Flow Sensor is some type of a shut-off valve such as a square nut, resilient seat gate valve (size as needed), especially if the P.O.C. components, Master Valve, and Flow Sensor are at a lower elevation than the rest of the park. If you ever need to work on the Flow Sensor, Master Valve, R.P.P.D., or other item, the shut-off valve will allow you immediate access to the internals of these components. Without a shut-off valve, you could literally spend all day draining and pumping water out of your valve box before being able to work on these items. Installation Stage D - Conduit & Conductor Installation When running conduit from the satellites to the Master Valves and Flow Sensors, you may encounter many obstacles in your path. In many existing park settings, you'll come across asphalt parking areas, concrete sidewalks, buildings, etc. It is relatively easy nowadays to bore across large expanses of asphalt, etc. with a directional boring machine. You can "pinpoint" where your conduit runs can be installed. If you can afford the extra cost of installing large 3-inch to 6-inch sleeves with these boring machines, you'll be able to use these sleeves not only for your conduit but other items in the future if you ever decide to expand your system. Installing E.M.T. conduit on building walls and overhangs allows you to route your conductors out of existing utility rooms from the satellite locations toward the Master Valve and Flow Sensor. Also, the use of a "guy-wire" from rooftop to rooftop will allow you to run telephone lines, etc. over to your satellite locations. All of these ideas will give you much flexibility in your installation process. Additional spare conductors for any new or future R.C.V.s can also be added at the same time you pull your Master Valve and Flow Sensor conductors through the conduit. Conductor size and color will depend upon the brand of Master Valve and Flow Sensor used. Distance from the satellite to each component will also determine conductor size. Typically, an A.W.G. #14-1 Type U.F. conductor is used for both items. After running conductors to the Master Valve and Flow Sensor, it is critical to "waterproof" all electrical connections and also to tag or ID all splices in valve boxes, pull boxes, and splice boxes. To be absolutely sure that all connections will not pull apart, all copper splices should be soldered with a rosin core solder. Wire nuts and barrel crimps are used to insulate connections. Also, a product called Splice-Kote(TM) Heat Shrink Insulation Sleeves, which are heat shrink products with a hot melt thermoplastic inner wall adhesive that completely seals off the conductor connections from any moisture whatsoever, are highly recommended. Waterproof conductor connections are a must for all irrigation applications. Rough backfilling, jetting, compacting, and cleanup are the final labor tasks to complete the plumbing portion of the project. Installation Stage E - Satellite & Central Computer Installation I usually leave this step as the last part of the retrofit so that the system can still be up and running once the water is turned back on after installing the P.O.C. components. It also gives the maintenance crews or irrigation technicians enough time to go through the entire system and sort out any discrepancies in the wiring sequence of the R.C.V.s. These installation steps are modular and can be installed in any order of preference to keep the project moving forward. I recommend that all satellites be properly grounded using the manufacturer's recommended guidelines. The use of E.M.T. conduit, rigid steel conduit, or flexible steel conduit should be used in all above ground satellite installations if you want a professional looking installation. P.V.C. conduit should only be used below ground and never above ground. All conductors should be tagged with numbers, and spade or fork connectors should be used on all terminal locations. 120 V.A.C. power to the satellite should be installed on a dedicated, non-G.F.I. (Ground Fault Interrupter) circuit breaker. All 120 V.A.C. duplex outlets downstream of the 120 V.A.C. power to the satellites should have G.F.I. protected outlets. The Central Computer should be located in a clean, dry, "Rat-Proof," sun-free, office or utility room where the irrigation manager can have easy, non-interrupted access. Having access to all satellites from the central location will again depend on the method recommended by the manufacturer of the C.C.I.S. Testing of the entire system should be completed as soon as all components have been installed and activated. All manufacturers provide some type of training for all personnel responsible for operating the system. Installation Stage F - Final Inspection, As-Built Drawings, & Photo Documentation After all of the C.C.I.S. components have been installed, the on-site inspector or person(s) in charge of maintaining the system should complete a final inspection. As-Built drawings and installation photographs should be provided for all phases of the job in a binder and on CD ROM for future reference in case work needs to be done on the system. With today's technology, digital cameras and digital video allow for extremely easy documentation of all work performed. You can now have "before & after" documentation of your entire parks stored digitally on DVD or CD ROM format. Accurate drawings and photographs can save numerous hours of unneeded repairs to the system or in aiding in the location of lost or buried components years after the installation of the C.C.I.S. Proper planning and installation of a new C.C.I.S. is a time-consuming yet rewarding experience. Cutting corners to make the budget or to save time will only hurt the overall performance of your system. Following the above guidelines will help ensure that your project will run smoothly and perform beyond your expectations. Dave Bakke is a second generation Irrigation Consultant with over 25 years experience specializing in all aspects of landscape irrigation such as irrigation consulting & design, irrigation trouble-shooting, installation, water auditing, water management, backflow prevention device testing & repair. The author wishes to thank the following people for being able to show photos of actual installations of Central Control components. From the City of Cupertino Parks Department's Bob Rizzo, Joe Moore, Shawn & Paul Tognetti, Ralph Garcia, Brian Gathers, and Mike Laitila. Thanks also go to Kevin Olimpia with Romeri Landscape Construction, the crew of West Valley Construction, and Sam Bakke with Global Span Products. For additional pictures and information contact Dave Bakke at (408) 379-0187.

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March 23, 2017, 11:20 am PDT

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Last Updated 03-20-17