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Avoid laying PVC pipe close to the trunks of trees, which can crush pipe.

Reducing Irrigation MaintenanceBy John Blevens

Like most other decisions, featuresselected for irrigation systems arebased on the experiences of the

person making the choices. You shouldrealize very early in your career that atremendous amount of experience fromothers is available, and tap it.Over the years, I have sought out

opinions from people in different facetsof the irrigation industry to try torefine designs for better systems. I callon distributors for product reliability,for they are usually the first to knowabout a product problem and are verywilling to share the information, sothey have to deal with it as little aspossible. Maintenance people are agood source of longer-term productreliability and assembly methods. Thecontractor is a good source for practicalconstruction methods, includingassembly techniques.From these sources and my own

experience, I have gleaned the follow-ing desirable and undesirable featuresof the various components in irrigationsystems.PipingIn the West, PVC pipe predomi-

nates, except for drip systems, andeven then it is used for some drip/bub-bler systems.Since my experience is largely con-

fined to this type of system, I willrestrict my comments to PVC pipe.

1. Expansion. Most everyone hasseen the diagram showing piping

REMOTE CONTROL VALVEWATERPROOF WIRECONNECTORS

PVC SCHEDULE 8012" T.O.E. NIPPLE(LENGTH SUFFICIENTFOR VALVE REMOVALIF NEEDED)

RECTANGULAR PLASTIC VALVEBOX (AMPLE SIZE FOR VALVEACCESS)

PVC SCHEDULE 80 2"T.O.E. NIPPLE

FINISH GRADE ---,

SLIP FITTINGS --~'TO PREVENTSTRESS FROMOVERTIGHTENEDTHREADEDCONNECTIONSCONTROLWIRES

3" MIN.

INSTALL DRAIN ROCK 2"MIN. BEYOND PERIMETEROF VALVE BOX

PVC SCHEDULE 80TEE (SxSxS) OR 90°ELL (SxS)DRAIN ROCK -1

12" MIN. DEPTH FOR DRAINAND RODENT BARRIER

IRRIGATION SPRINKLERLINESUMP

Remote Control Valve Installation Detail

26 sporlsTURF· http://www.sporsturfonline.com

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"snaked" along a trench, to be used asa guide for the contractor to followwhen installing PVC pipe to allow forthermal expansion. I have yet to see apipe snaked in a manner that in anyway resembles that type of diagram.PVC material has a high thermal

expansion coefficient, potentially mak-ing it a critical factor. In temperateareas, the temperature change 12 to24 inches below grade is very minimal.Nonetheless, stresses can be createdfrom temperature variations in longruns of pipe.Large-sized main lines are almost

always used in projects requiring longruns. Therefore, we specify gasketedpipe for main lines of 3 inches andlarger to account for expansion. In sit-uations where 2- or 2 1/2-inch pipeshave abnormally long runs, gasketedpipe should also be considered. In mostsituations, lateral piping is not anissue.2. Threads. Threaded connections

should be avoided in most cases usingPVC pipe, particularly in main lineconnections. Sprinkler risers (exclud-ing valve-in-head) where leak-tight

connections are not critical is anexception.Plastic threaded connections create

a dilemma, because tightening theconnections to avoid leaks is highlydesirable: disassembling connections,adding sealant and re-assembling theconnection to stop leaks is a disagree-able, time-consuming hassle. But as aresult, threaded connections tend tobe over-tightened, creating stress.These connections are susceptible tocracking when additional stresses areintroduced by water flow or by turningvalves on and off.3. Differential. Lateral piping

should be sized for minimal pressuredifferential between the first headnearest the control valve and the lasthead at the end of the line. As a gen-eral rule, 10 percent is a maximumdifferential to improve uniformity andreduce coverage problems.4. Trees. Trees surrounding a

sports field can play havoc when PVCpipe is installed too close to theirtrunks. This problem seems to be morefrequent as tight plant spaces increase.Aggressive roots can crush pipe.

Valves1. Transition. Valve assemblies

that crack at male adapters have beena persistent problem. This is a weakpoint in valve assemblies and shouldbe eliminated.Galvanized steel pipe is mechani-

cally strong but corrodes in many soilsand from elements carried in water.Brass is also a strong material, but isexpensive. With either material, thetransition from the plastic pipe to thethreaded connections is still an issue.The best solution is to use schedule

80 PVC nipples threaded one end(t.o.e.) - which increases the connec-tion's strength and also makes the slip-to-thread transition effectively. Theset.o.e. nipples are placed on either sideof the valve and connected to PVC pipeusing slip couplings. For larger pipes,of course, you should use an appropri-ate flange coupling adapter.2. Shut-Offs. Often, not enough

shut-off valves are installed in largeprojects. Maintenance is made easierwhen major sections can be isolatedwith these valves. In addition, theycan be helpful in shutting down sec-

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tions in emergencies or if constructionis later done at a portion of the site.3. Pressure Regulators.

Sometimes pressure-regulating valvesare also not installed when they areneeded. Excessive pressure can signif-icantly reduce the life of a system,especially when water-flow rates arehigh. Under high pressure, flow ratesthrough sprinkler nozzles are oftenhigher than the design flow, which inturn means higher rates in the piping.High flow rates cause water hammerand induce extreme stresses that candamage pipe, fittings and other systemcomponents. Proper pressure regula-tion eliminates these problems.Partially closing gate valves or con-

trol valves is not the way to do it. In afew situations where the pressure isnot too great or never varies, this tech-nique can work, but generally is notrecommended.4. Quick Couplers. I suspect that

a great many quick-coupling valveshave been installed but never used, orhave only been used to water-in plantsduring establishment. Those valvesshould be installed only in situations

where they have a possible use.Place them in a round box, set

above grade by a minimum of an inch,to make them easier to find. Bracingthem with angle iron will providegreater stability than rebar or galva-nized stakes. When at the end of ahose and tugged, the angle iron willreduce the likelihood of joint looseningand leaking.Control Valves

1. Connectors and Wires. Thereshould no longer be any doubt as tothe value of waterproof connectors,especially now that several good, inex-pensive, easy-to-use brands are avail-able. The type using heat-shrinkabletubing with an inner wall sealant, inmy opinion, is superior to all the rest.But those types take a blowtorch toinstall.Coiling the control wires at the

valve makes finding the wires easierand is a compact way to store excesswire that may be needed if replacingsolenoids becomes necessary.2. Boxes. Valve boxes should be of

ample size and centered above thevalve for good repair access. Also,

valves should be raised from the mainline to within a few inches from top ofgrade for easy access.3. Ball Valves. Installing inexpen-

sive plastic ball valves in front of con-trol valves is very handy for servicingand/or replacing solenoids anddiaphragms. Some public agenciesrequire that one or two unions beinstalled with the control valves. Sincesolenoids and diaphragms are themost frequently serviced items, Iwould choose the ball valves overunionts). Very seldom does the entirebody of a valve have to be removed.4. Gravel. Installing gravel

beneath the valve not only provides asump during manual bleeding or whileservicing the valve, but also provides abarrier to gophers from getting to thevalve and filling up the valve box withdirt. The gravel should be a minimumdepth of 12 inches and at least twoinches beyond the perimeter of the bot-tom edge of the valve box.5. Threads. Just as you should

avoid threaded pipe connections, soshould you avoid threaded connectionson the control valve assembly. If

28 Call 1(800) 817-1889 use Fast Fax #1160497 and/or Circle 116 on Postage Free Card

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threaded connections are necessary, Iurge that you make, at the minimum,a slip connection at the tee joining theassembly to the supply line. A brokentee is a major repair project.Sprinklers1. Height. Selecting the appropri-

ate pop-up height for the plant mate-rial being irrigated can avoid majorproblems as the material matures.This may include coordinating plant-ing and irrigation plans so heads andshrubs/trees are not too close to eachother. When this cannot be avoided,such as in tight areas with shrubmasses, flat sprays shooting underthe shrubs or bubblers to flood theroot areas can be appropriate options.2. Hose. Flexible hose with

thread/insert adapters (and maybeone or two street ells) or the tripleswing seem to be the most favored forriser assemblies. A quintriple swingassembly - mainly for part-circlerotor heads - allows the head to berotated to the desirable location onceit's set at the correct height. A goodway to keep PVC pipe away from treeswhen irrigating them with bubblers isto use flexible PVC hose from the PVClateral line to the rootball.Drip Vs, OverheadDrip irrigation is a good tool, but

should be used only when appropriate.There must be access as plant materi-al matures (except for temporary irri-gation during establishment only),and sub-grade drip should not be usedwith ground covers that have aggres-sive, invasive roots.

If a drip system is installed in anenvironment that prevents repair andmaintenance access, it will be a failure- at least in the longer term.On the other side of the coin, I have

seen overhead systems used in narrowstrips where drip would be much moreeffective.Since this is an article about sports

turf, I will not say any more about dripmaintenance except that it is an arti-cle in itself. I predict that drip willplay a larger role in irrigating sportsfields in the future. Eliminating pop-up sprinklers, sub-grade drip is a safersystem for athletic fields, and eventu-ally it will be proven reliable in thelong haul.SensorsSensors - especially flow sensors -

can obviously reduce maintenancework. I believe we will see, in the nearfuture, a large increase in the numberof stand-alone controllers that will be

able to interpret flow-sensing inputand react and report on exceptionalflow events.

Rain sensors, for the most part, areeasy to add and are a minor cost. Inthe spring and fall, they can savemany trips to controllers for adjust-ments.

Moisture sensors have their place,but in many situations they have not

been effective. Sports fields can be agood application, if scheduling issuescan be satisfactorily controlled.Moisture sensors in more complexlandscapes, from my observations,have not been successful.

John Blevens, a member of ASIC, isan irrigation consultant based in SanCarlos, Calif His phone number is(415) 802-8236.

YOU COULD BEHONORED BY THEPROS!Why not enter your baseball field in theBeam Clay®Baseball Diamond of the YearAwards contest? You need not be a cus-tomer, member, or subscriber; and there isno entry fee. You could be featured insportsTURF magazine and receive anofficial a\yards plaque.

The Awards are sponsored by BeamClay,® sportsTURF magazine, andthe Sports Turf Managers Assoc.,in recognition of excellence andprofessionalism in maintainingoutstanding, safe, professionalquality baseball diamonds.Entries will be judged in threecategories: professional diamonds; collegediamonds; and school, municipal or park diamonds.

Send the information below to enter:1. Age of baseball diamond (year of installation);2. Geographic location (city and state).3. Description of maintenance program.4. Operating budget for baseball diamond.5. Irrigation: None Manual Automatic _6. Total number of maintenance staff for field.7. Does baseball field have lighting for night garlJ€s?8. Number of events on baseball diamond per year.9. Types and number of events on diamond other than baseball?10. How many months during the year is the field used?11.Why,you think this field is one of the best?12. IMPORTANT: Send two sets of color slides or prints.

Deadline for entries: Entries must be postmarked.no lateri#~hanNovember 30. Selection of winners will be made by theAwards Committee of Four Major League Head Groundskeepers.

Mail entries to:Beam Clay AwardsKelsey ParkGreat Meadows, NJ07838 •r/E. PAOFESS10liAI:S:<>«E

.• :SlNCE1922

S/I'I'IsTUR'magazine

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