ChemigationChemigation

Guy Fipps – Extension Agricultural Guy Fipps – Extension Agricultural EngineerEngineer

Shay Simpson – Extension Shay Simpson – Extension AssociateAssociate

88thth Annual Southeast Texas Annual Southeast Texas Grounds Maintenance ConferenceGrounds Maintenance Conference

October 25, 2001October 25, 2001

RegulationsRegulations

• Administrative Rules of the Texas Administrative Rules of the Texas Department of Licensing and Department of Licensing and Regulation (TDLR):Regulation (TDLR): Chapter 76 – Chapter 76 – Water Well Drillers and Pump InstallersWater Well Drillers and Pump Installers

• Texas Natural Resource Texas Natural Resource Conservation Commission Conservation Commission (TNRCC):(TNRCC):– Chapter 290 – Public Drinking WaterChapter 290 – Public Drinking Water– Chapter 344 – Landscape IrrigationChapter 344 – Landscape Irrigation

• Local OrdinancesLocal Ordinances

TDLR Chapter 76.1007TDLR Chapter 76.1007Water Well Drillers and Pump Water Well Drillers and Pump

InstallersInstallersSection 76.1007. Technical Section 76.1007. Technical

Requirements - Chemical Requirements - Chemical Injection, Chemigation, and Injection, Chemigation, and Foreign Substance SystemsForeign Substance Systems

TDLR Chapter 76.1007TDLR Chapter 76.1007

All irrigation distribution systems All irrigation distribution systems … into which any type of … into which any type of chemical … or other foreign chemical … or other foreign substances will be injected into substances will be injected into the water pumped from wells the water pumped from wells shall be equipped with an in-line, shall be equipped with an in-line, automatic quick-closing check automatic quick-closing check valve capable of preventing valve capable of preventing pollution of the ground water.pollution of the ground water.

Check ValveCheck Valve

• Body constructed of:Body constructed of:– Cast ironCast iron– Stainless steelStainless steel– Cast aluminumCast aluminum– Cast steelCast steel– Material and design of sturdy integrityMaterial and design of sturdy integrity

• Materials should be corrosion Materials should be corrosion resistant or coated to prevent resistant or coated to prevent corrosioncorrosion

Check ValveCheck Valve

• Valve working pressure rating Valve working pressure rating shall exceed the highest pressure shall exceed the highest pressure to which the valve will be to which the valve will be subjectedsubjected

• Valve shall be installed between Valve shall be installed between the pump discharge and the point the pump discharge and the point of chemical/foreign substance of chemical/foreign substance injectioninjection

Other Required Devices Other Required Devices Installed between the pump Installed between the pump

discharge and the check valvedischarge and the check valve

• Vacuum-relief deviceVacuum-relief device• Automatic low pressure drainAutomatic low pressure drain

– At least ¾ inch in diameterAt least ¾ inch in diameter– Flush with inside surface of pipe Flush with inside surface of pipe

bottombottom– Outside opening be at least 2 Outside opening be at least 2

inches above gradeinches above grade• Inspection portInspection port

– Minimum of 4 inch diameter orificeMinimum of 4 inch diameter orifice

TNRCC – Chapter 290TNRCC – Chapter 290Public Drinking WaterPublic Drinking Water

Appendix I: Assessment Appendix I: Assessment of Hazards and Selection of Hazards and Selection

of Assembliesof Assemblies

Irrigation With Chemical Irrigation With Chemical AdditivesAdditives

• Health hazardHealth hazard

• Required assemblyRequired assembly– Reduced-pressure principle Reduced-pressure principle

backflow prevention assembly backflow prevention assembly (RPBA)(RPBA)

Irrigation Irrigation WithoutWithout Chemical AdditivesChemical Additives

• Non-health hazardNon-health hazard• Required assembly*Required assembly*

– Double check valve backflow Double check valve backflow prevention assembly (DCVA)prevention assembly (DCVA)

– Atmospheric vacuum breaker Atmospheric vacuum breaker (AVB)(AVB)

– Pressure vacuum breaker (PVB)Pressure vacuum breaker (PVB)

*Where greater hazards exist reduced-*Where greater hazards exist reduced-pressure principle backflow prevention pressure principle backflow prevention assembly is required.assembly is required.

TNRCC – Chapter 344TNRCC – Chapter 344Landscape IrrigationLandscape Irrigation

Proposed Revision Proposed Revision

An irrigation system which adds An irrigation system which adds any chemical with any kind of any chemical with any kind of injection device associated with injection device associated with it has a potential for introducing it has a potential for introducing toxic substances into the water toxic substances into the water supply and is, therefore, supply and is, therefore, considered to be a "high health considered to be a "high health hazard" installation. hazard" installation.

Proposed RevisionProposed Revision

Such an irrigation system must not Such an irrigation system must not be connected to any potable be connected to any potable water supply except through an water supply except through an industry-approved "high health industry-approved "high health hazard" backflow prevention hazard" backflow prevention device, such as an appropriate device, such as an appropriate pressure-type vacuum breaker pressure-type vacuum breaker backflow preventor or a reduced backflow preventor or a reduced pressure principle backflow pressure principle backflow prevention assembly.prevention assembly.

Proposed RevisionProposed Revision

The backflow prevention The backflow prevention assembly must be tested assembly must be tested upon installation and, at upon installation and, at least, annually, thereafter, in least, annually, thereafter, in accordance with §290.44(h)accordance with §290.44(h)(4) of this title (relating to (4) of this title (relating to Water Distribution).Water Distribution).

Reduced-Pressure Reduced-Pressure Principle Backflow Principle Backflow

Prevention AssemblyPrevention Assembly• RPBARPBA• RPZRPZ• RPRP

RPBARPBA

• Protects against back-Protects against back-siphonage & back-pressuresiphonage & back-pressure

• Can be under constant pressureCan be under constant pressure• Must be 12 inches above gradeMust be 12 inches above grade• Must be tested upon Must be tested upon

installation and annually if in installation and annually if in high hazard applicationshigh hazard applications

RPBARPBA

• Installed horizontallyInstalled horizontally• 4 test cocks4 test cocks• 2 shut off valves2 shut off valves• At least 2 (psi) zone pressure At least 2 (psi) zone pressure

differencedifference• Double seated relief valveDouble seated relief valve

ChemigationChemigation

The process of injecting an The process of injecting an approved chemical into approved chemical into irrigation water and applying it irrigation water and applying it through the irrigation system through the irrigation system to a crop or field.to a crop or field.

ChemigationChemigation

• FertigationFertigation• InsectigationInsectigation• FungigationFungigation•NematigationNematigation

Advantages of Advantages of ChemigationChemigation

• Uniformity of applicationUniformity of application• Precise applicationPrecise application• EconomicsEconomics• TimelinessTimeliness• Reduced soil compaction and Reduced soil compaction and

crop damagecrop damage• Operator safetyOperator safety

Disadvantages of Disadvantages of ChemigationChemigation

• High managementHigh management• Additional equipmentAdditional equipment

The US EPA’s Label The US EPA’s Label Improvement Program Improvement Program

(LIP)(LIP)• Effective April 1988Effective April 1988• Labels must state whether Labels must state whether

product is approved to be applied product is approved to be applied through the irrigation systemthrough the irrigation system

• Application instructions are Application instructions are providedprovided

• Requires use of specific safety Requires use of specific safety equipment and devices designed equipment and devices designed to prevent accidental spillsto prevent accidental spills

Example LabelsExample Labels

Summary of Summary of Chemigation Equipment Chemigation Equipment

RequirementsRequirements

1. Irrigation Pipeline1. Irrigation Pipeline

• Check valve between well and Check valve between well and injection points*injection points*

• Vacuum relief valve between Vacuum relief valve between check valve and wellcheck valve and well

• Low pressure cut offLow pressure cut off• Low pressure drain*Low pressure drain*

*Alternative safety equipment may be *Alternative safety equipment may be substituted substituted approved by EPA, March 1989.approved by EPA, March 1989.

2. Injection Hose2. Injection Hose

• Anti-back flow injection valve – Anti-back flow injection valve – 10 psi10 psi

• Normally closed solenoid valve Normally closed solenoid valve between injection pump and between injection pump and chemical tank*chemical tank*

• A metering type injection A metering type injection pump*pump**Alternative safety equipment may be *Alternative safety equipment may be substituted substituted approved by EPA, March 1989.approved by EPA, March 1989.

3. Power Interlock3. Power Interlock

• Interlock injection pump and Interlock injection pump and water pump powerwater pump power

• Interlock normally closed Interlock normally closed solenoid valve and injection solenoid valve and injection pump powerpump power

Management Practices Management Practices for Chemigationfor Chemigation

• Flushing injection systemFlushing injection system• Flushing irrigation systemFlushing irrigation system• MonitoringMonitoring• Calibration checkCalibration check• Chemical compatibilityChemical compatibility• Prevent runoffPrevent runoff• Prevent application to surface Prevent application to surface

waterwater

Chemigation PumpsChemigation Pumps

• MechanicalMechanical– Piston (positive displacement) Piston (positive displacement)

pumpspumps– Diaphragm pumpsDiaphragm pumps

• Venturi metersVenturi meters

Piston/Positive Piston/Positive Displacement PumpsDisplacement Pumps

Discharge flow rate will not change Discharge flow rate will not change as the irrigation pipeline pressure as the irrigation pipeline pressure variesvaries

• Flow rates cannot be adjusted Flow rates cannot be adjusted while operating while operating

• Used to inject fertilizerUsed to inject fertilizer• Not easily adjusted for insecticides, Not easily adjusted for insecticides,

fungicides and herbicidesfungicides and herbicides

Diaphragm PumpsDiaphragm Pumps

Discharge flow rate not constant Discharge flow rate not constant with significantly varying with significantly varying

discharge pressuredischarge pressure

• Easy to adjust flow rate while Easy to adjust flow rate while operating operating

• Zero leakageZero leakage

Venturi MetersVenturi Meters

Variations in flow rate from the water Variations in flow rate from the water supply will change the rate of supply will change the rate of

injectioninjection

• Reduced diameter throat tubeReduced diameter throat tube• Velocity changes in throat create Velocity changes in throat create

vacuum to pull chemical into streamvacuum to pull chemical into stream• Requires additional hardware for Requires additional hardware for

injectioninjection

Important Important CharacteristicsCharacteristics

Chemigation Pumps & Chemigation Pumps & ComponentsComponents• Accuracy to within + or – 0.5 Accuracy to within + or – 0.5

percentpercent• Calibration tubeCalibration tube• Adjustable while runningAdjustable while running• Durable – stainless steel valve ballsDurable – stainless steel valve balls

– Niton seals – Niton seals • Agitation capabilityAgitation capability• Accessibility of repairsAccessibility of repairs• Appropriate size chemical Appropriate size chemical

tank/tankstank/tanks

Calibration of Calibration of EquipmentEquipment

• Small differences in injection Small differences in injection rates make large differences in rates make large differences in total amount of chemical appliedtotal amount of chemical applied– Results in insufficient or excessive Results in insufficient or excessive

applicationapplication

450 gallons/minute = 1 450 gallons/minute = 1 acre-inch/houracre-inch/hour

27,000 gallons = 1 acre-inch27,000 gallons = 1 acre-inch

Example CalibrationExample Calibration

Precipitation RatePrecipitation Rate

• Amount of water applied per Amount of water applied per unit timeunit time

• Meter methodMeter method• Area flow methodArea flow method• Catch can methodCatch can method

Example of Example of Precipitation RatePrecipitation Rate

Distribution UniformityDistribution Uniformity

• Provides an analysis of water Provides an analysis of water application over area irrigatedapplication over area irrigated

• Expressed in percentExpressed in percent• 70 to 80% is considered good70 to 80% is considered good

Distribution UniformityDistribution Uniformity(DU) (%)(DU) (%)

• Ratio: dry vs. wet areasRatio: dry vs. wet areas• Based on irrigation system Based on irrigation system

hardwarehardware• Easy to measure using catch Easy to measure using catch

devicesdevices• Limiting factor when producing Limiting factor when producing

good schedulesgood schedules• Limiting factor for good Limiting factor for good

chemigation applicationchemigation application

The Eight Steps of an The Eight Steps of an AuditAudit

Site SelectionSite Selection Step 1: Obtain site data Step 1: Obtain site data

Step 2: Rank the sitesStep 2: Rank the sites

Field WorkField Work Step 3: Inspect the site Step 3: Inspect the site

Step 4: Prepare for the irrigation Step 4: Prepare for the irrigation system tests system tests

Step 5: Perform irrigation system testsStep 5: Perform irrigation system tests

Step 6: Calculate base irrigation Step 6: Calculate base irrigation schedule schedule

Follow-upFollow-up Step 7: Prepare reports, adjust Step 7: Prepare reports, adjust

schedule schedule

Step 8: Review performance Step 8: Review performance

Landscape Irrigation Landscape Irrigation Auditing and Auditing and

Management (LIAM)Management (LIAM)Short CourseShort Course

http://http://irrigation.tamu.eduirrigation.tamu.edu