Landscape Irrigation Slide Set and Narrative Provided by Dr. Brian G. Leib Dr. John Buchanan Biosystems Engineering & Environmental Science Agricultural Extension Service The University of Tennessee 2005 Commercial Horticulture In-Service

Design and Management Factors 1. Water Supply Requirements and Limitations 2. Scale Drawing of the Site 3. Sprinkler/Drip products that Match the Landscape 4. Spacing of Sprinklers 5. Sprinkler Zones 6. Pipe Sizing 7. Irrigation System Equipment 8. Programming an Irrigation Controller

How Much Water is Required? 0.7 inches per week2.0 gpm/ac in 24hr/da 1.0 inch per week3.0 gpm/ac in 24hr/da 1.5 inches per week4.5 gpm/ac in 24hr/da Irrigate all at one time80 gpm/ac in 2 hr/day Allows some flexibility15 gpm/ac in 7 hr/da

Surface and Ground Water Sources Rivers and Lakes may provide a Non Limiting Supply Creeks and Ponds; however, may Constrain the Landscape Irrigation System to Supply Limitations

Municipal Water Sources Utility Water and Well Water usually constrain the flow available to a Landscape Irrigation System

Measuring Flow and Pressure Example - Measuring the flow and pressure from a residential hydrant  connection to hydrant  tee fitting  pressure gauge  ball valve  5 gallon bucket & stop watch or municipal flow meter

Pressure and Flow Rate Pressure and Flow Rate are Related (pressure vs. flow rate is different for every system)

Proper Equipment: Rotating Sprinklers A single sprinkler can cover a large area, 20 to 60 foot radius Needs a higher flow rate, 0.5 to 20 gpm Needs higher pressure, 35 to 75 psi Sprinklers are “constant discharge” and do not automatically provide “matched precipitation” when part-circles are used

Sprayer Sprinklers Wets a smaller area, 8 to 16 foot radius Smaller water flow, 0.25 to 4 gpm Less pressure required, 20 to 40 psi Can wet rectangular areas Automatic “matched precipitation when part- circles sprinklers are used

Bubblers good applications in plant beds wets a small area low pressure requirement, 15 to 30 psi low flow rate, 8 gph to 2.5 gpm

Drip Emitters and Dripline Good applications in plant beds and vegetable and fruit gardens very low flow rate, 0.5 to 2.0 gph very low pressure, 10 to 25 psi (pressure compensating emitters are designed for a greater pressure range) direct application of water to root zone of individual plants water must be very clean to prevent clogging of emitters

Ideal Pressure and No Wind How Much Water in the Cans? Even in all cans More in cans closer to the sprinkler More in cans further from the sprinkler Uniformity of Water Caught in Cans around a Single Sprinkler

Sprinkler Overlap For Uniformity Distance between Sprinklers = Radius of Throw Head-to-Head Spacing: 1. Good Uniformity 2. Good Economics

Rules for Spacing Sprinklers. 1. Pick a sprinkler with a wetted radius that is as large as possible and does not greatly exceed the shortest distance across the area. 2. Place part-circle sprinklers at all corners 3. Place part-circle sprinklers at an even spacing on the edges between corners using head-to-head spacing as a guide. 4. Place full-circle sprinklers in the interior area using the same head-to- head spacing used on the edge sprinklers. 5. Perfect head-to-head spacing is impossible in most cases. It is O.K. to stretch and/or crowd the spacing by 10%. 6. Adjust the sprinklers to even out the spacing over the entire area and don’t leave a big gap in one area to make the rest of the area even. Are most landscape areas simple squares and rectangles?

Example Landscape Sprinkler Layout

Zones Avoid Excess Flow Demand A Zone is a group of sprinklers that operate together on the same lateral pipe network downstream from a common valve. Limited Flow Rate of 12 gpm at 45 psi and sprinklers that require 3 gpm 8 sprinklers x 3 gpm/spr = 24 gpm > 12 gpm, a severe pressure drop will occur. 20 psi

Zones Allow Equal Application of Water from Different Equipment Rotating Sprinkler, Full Circle – 0.25 in/hr Sprayers: Full, ½, & ¼ Circle – 1.5 in/hr Rotating Sprinkler, Half Circle – 0.5 in/hr Rotating Sprinkler, Quarter Circle – 1.0 in/hr Drip – 0.1 in/hr

Sizing Pipe with a Velocity Method Flow is Q = 20 gpm 1.5” pipe 1” pipe Proper pipe sizing will reduce friction loss, improve uniformity, save material costs, lower pumping costs and control waterhammer. Velocity Method Locate pipe network for irrigation system. Determine the flow in each section of pipe. Determine the smallest size pipe that keeps flow velocity below 5 feet per sec (fps) Pipe charts are available in most Irrigation Supply Catalogs V = 2.65 ft/sec F L = 0.71 psi/100’ V = 5.71 ft/sec F L = 4.59 psi/100’

Simplified Pipe Chart based on 5 ft/sec Rule Class 160 PVC Pipe Size in Inches Flow (gpm) 11 – 15 1 ¼16 – 28 1 ½29 – – 59 2 ½60 – – – – – 450

S M Source 1. Corp. Valve 2. Gate Valve 3. Water Meter 4. Backflow Preventor 5. 2” PVC Mainline 200’ ’ Diaphragm Valve ” 20 gpm 8. 1” 9. 1” 10. 1” 40 gpm 15 gpm 10 gpm 5 gpm 11. ¾” or ½” Swing Joint POC Pipe Size in a Zone & Mainline Based on 5 gpm per Sprinkler

Backflow Prevention If you use utility water  you must have backflow prevention installed  prevents water from flowing backwards into the supply line in case of pressure-loss from within the system industrial-sized backflow prevention

Swing Joints for Sprayers and Sprinklers Use a flexible connector-piping from lateral to sprinkler  allows the sprinkler to be set at the correct depth and to be moved deeper if the soil settles  allows sprinkler to move it run-over by tractor tire  reduces damage to lateral

Valves for Irrigation Zones (sets) Valves off of the mainline control individual sets  can be manual valves or electric valves  electric valves are needed when using timers

24 V-AC Solenoid Valves Magnetic coil is used to open a spring-loaded valve  very common application  easy to rebuild or replace  allows for manual operation

Controller (timer) Normal Program  Days of the week to water – MTWThFSaSu  Start time during the day to initiate the valve sequence  Valve run time of each zone (set) Special Features Available:  Rain Delays  Raingauge shutdown  Soil sensor shutdown

A r = 96.3 Q = Application rate in inches per hour A Q = Flow or discharge in gallons per minute A = Area into which flow is applied in feet^2 Example: A full-circle sprinkler discharges 2.4 gpm and the sprinkler spacing is 30 by 30 feet. Ar = (96.3 x 2.4) / (30 x 30) = 0.25 inches per hour Application Rate – Flow into an Area

Z 11.0 in/hr Z 20.5 in/hr Z 31.0 in/hr Precipitation Rate Precipitation Rate 2.0 in/hr Z 4 Set Controller to apply 0.5 inches 2 days per week = 1 inch per week Time for zone 1 = 0.5in / 1.0 in/hr = 0.5 hours or 30 min. M Th Valve Tz On Off 130 min10:0010: min10:3011: min11:3012: min12:0012:15 Controller Settings and Irrigation Scheduling

Uniformity Impact on Operating Cost Six inches of water required on a half acre lot Municipal Water Cost of $0.61/100gal Driest 10% receives 66% of requirement UniformityWater AppliedIrrigation Cost inches 85%6.0 $ %6.2 $ %7.2 $ %10.8 $

Resources Landscape Irrigation Design by Eugene W. Rochester, ASAE Publication #8, X Simplified Irrigation Design by Pete Melby, John Wiley & Sons, Inc., ISBN Ortho’s All About Sprinklers and Drip Systems, Meredith Books Inc, ISBN Drip Irrigation for Every Landscape and All Climates by Robert Kourik, Metamorphic Press, ISBN