EXHIBIT A.pdf

EXHIBIT A

IRRIGATION SYSTEM EVALUATION PROCEDURES

Table of Contents:

Page

IRRIGATION SYSTEM EVALUATION PROCEDURES 2

Introduction 2

Performance Terms 2

Farm Irrigation Rating Index (FIRI) 4

EVALUATION OF MICROIRRIGATION SYSTEMS 6

EVALUATION OF SPRINKLER IRRIGATION SYSTEMS 11

EVALUATION OF FIXED AND PORTABLE LATERAL SPRINKLER SYSTEMS

(SOLID SET AND LINEAR MOVE)

EVALUATION OF TRAVELING GUN SPRINKLER SYSTEMS 16

EVALUATION OF CENTER PIVOT SPRINKLER SYSTEMS 17

EVALUATION OF SUBIRRIGATION SYSTEMS (FLOW THROUGH AND

UNDERGROUND CONDUIT

DETERMINING WATER SAVINGS 27

REPORTING WATER CONSERVATION RESULTS TO FDACS AND GROWERS 38

RESOURCES 46

SECTION 1 - INTRODUCTION

The major function of the MIL is to evaluate irrigation systems to determine the system efficiency, to provide recommendations for system maintenance, to provide recommendations on proper operation of the system, and to develop a site-specific irrigation water management

(IWM) plan. IWM plans are prepared in accordance with Florida Natural resources Conservation Service (NRCS) conservation practice standard, Irrigation Water Management, Code 449.

Evaluating an irrigation system consists of determining its performance by collecting data and identifying problems any problems that prevent the system from operating at its optimum level.

There are several types of irrigation systems, but the process by which they are evaluated is similar for all pressurized pipe irrigation system types. The performance can be determined by the uniformity with which the irrigation water is distributed to the crop and the percentage of the applied water that reaches the crop's root zone.

Before any field evaluation is performed on an irrigation system, the MIL will verify in advance with the irrigator if the irrigation system is in good working condition. If the system is not in good working order, the MIL will not proceed with the evaluation and schedule a future date to perform the evaluation when the irrigation system is operating under normal/typical conditions.

SECTION 2 - PERFORMANCE TERMS

The following terms are used to describe irrigation system performance:

1) Application Efficiency (Ea): This is a measure of the efficiency based on the current operating time. It is calculated by dividing the average depth of water stored in the plant root zone by the amount of water applied, diverted or pumped. Application efficiency accounts for all losses between the pump and the irrigated crop, including system leaks, evaporation, spray drift, deep percolation, and runoff.

For subirrigation systems, the application efficiency is estimated by using the NRCS Farm Irrigation Rating Index (FIRI) which considers several system and management factors.

2) Christiansen’s Coefficient of Uniformity (CU): A measure of the uniformity of irrigation water application. The average depth of irrigation water infiltrated minus the average absolute deviation from this depth, divided by the average depth infiltrated. CU is expressed as a percent. The CU value indicates on average how uniform the sprinkler application pattern is.

CU gives no indication of how low the uniformity may be for a particular localized area or how large that area might be.

3) Distribution Uniformity (DU): A term used for sprinkler systems; it is the uniformity with which the water is distributed over the field surface. Measured with catch cans, it is the ratio of the average amount of water caught in the lowest one-fourth (¼) of the catch cans, to the overall average. DU is expressed as a percent. A DU less than 70% is an indication of poor performance, a DU between 70% and 90% is an indication of good performance and a DU greater than 90% is an indication of excellent performance.

4) Effective Portion of Water Applied (Re): The effective portion of water applied is the amount that reaches the soil-plant surface. This is a measurement of the amount of water that evaporates before it reaches the catch cans. For systems with high application rates, the Re should be 1.0, but for systems with low application rates, especially when tested during hot weather, the Re could be less than 1.0.

5) Emission Uniformity (EU): A term used to describe the uniformity for microirrigation (drip or microjet) systems. This is the uniformity with which the water is applied to the individual trees or plants. It is a ratio of the average of the low one-fourth (¼) of the emitter discharge rates too the overall average, expressed as a percent. Emission uniformity is considered excellent above 90%, good 80% to 90%, fair 70% to 80% and poor below 70%.

6) Potential or Maximum DU or EU Efficiency: This is a measure of the best possible or maximum DU or EU, for each type of irrigation system. Such DUs or EUs have been obtained for several irrigation systems via field testing by the irrigation industry and/or research community over the years. They have also been verified via actual field evaluations conducted by the MILs over the years on different types of irrigation systems. NRCS has compiled a table of maximum DUs or EUs, which can be found in the Florida Supplement to the USDA NRCS NEH, Part 652, Irrigation Guide, Chapter 15, Table FL 15-1, System Potential Efficiencies. This document is located in the FOTG, Section I., C. References, 1. Engineering References, e. Part 652, Irrigation Guide – Florida Supplement, Chapter 15, at the following web address: http://efotg.sc.egov.usda.gov/treemenuFS.aspx.

A revised version of maximum DUs or EUs is shown in Table 4. Table 4 reflects updates to the maximum DUs or EUs that the MILs and the Irrigation Conservation Committee (ICC) have reviewed and approved over the years, based on their own evaluation results and/or new industry or research tests and results.

7) Seepage Irrigation System: a system of underground pipes connected to above ground spigots that delivers water from a pump station at low pressure to a graded field, so that water can infiltrate into the soil and raise the water table in that field towards the root zone of the plant.

SECTION 3 - FARM IRRIGATION RATING INDEX (FIRI)

The potential for improving systems for more efficient water use can be determined by field investigations. The real challenge is to develop a viable method for comparing the present irrigation system and management to feasible modifications which result in more efficient irrigation systems and improved management. A good rating system is needed because complete field evaluations are sometimes difficult and require staff time and money which are frequently unavailable.

FIRI was developed by NRCS using published data for most factors and estimates based on field experience for other factors. FIRI can be tested against field trials and complete field evaluations to refine and improve factors used in the system. FIRI provides a relative rating. It is the product of up to twelve management and system factors to rate consistently from one location to another the effectiveness of irrigation practices. When a potential efficiency is selected for a specific field and irrigation system, the rating will evaluate the difference between the gross volume of farm delivery and the net consumed by the plant. Additional evaluations are required for special water use to determine how efficient the system will apply water for frost protection, waste utilization, fertigation, or chemigation as examples. FIRI represents typical conditions and will only provide a rating for changes. FIRI is not a substitute for detailed irrigation evaluations but can be used as a tool in determining how the irrigation system and management can be improved.

FIRI can provide an approach to compare the present and future on-farm irrigation consistently by using a standard set of system and management factors. Information from FIRI can be used to provide irrigators:

http://efotg.sc.egov.usda.gov/treemenuFS.aspx.

(1) on farm irrigation improvements that can be implemented to achieve a specific level of water management and conservation; and

(2) estimated amount of water conserved when system or management factors are changed.

FIRI provides a uniform and simple method to analyze on farm irrigation water conservation. It provides documentation of the effects of change. It can document effects of annual practices or increments of a conservation plan for a farm tract. The method is the product of the following three elements:

1) The on-farm water management – The human element involves decisions which can be scientifically based on measuring water, monitoring soil moisture, and knowing how to operate the irrigation system efficiently. It also involves farmer decisions on a maintenance program, tillage operation, and conservation cropping systems. How the water delivery system is operated also affects decisions on when and how much water to apply. Once a system is in operation, a management plan is required.

The water management element is comprised of six (6) factors applicable to either surface, subsurface, drip/microirrigation, or sprinkler irrigation systems. The factors are as follows:

• Md – Water measurement

• S – Soil moisture monitoring and scheduling

• I – Irrigation skill and action level

• M – Maintenance plan for the system

• D – Water delivery constraint

• Sc – Soil condition

2) The on-farm irrigation system – For a sprinkler conservation are climatic effects, spray type, average wind speed, variation in nozzle pressure, and the key system component affecting water nozzle selection. Key system components for subirrigation are conveyance, uniformity of water table, capacity to maintain the desirable water table, surface slope, and prevention of tailwater loss. Key components for surface system are conveyance, distribution control, length of run, surface slope and prevention of tailwater reuse.

The irrigation system element is comprised of nine (9) factors. The factors are as follows:

• Wc – Water distribution control factor

• Ce – Conveyance efficiency factor

• L – Land leveling factor

• C – Climatic factor

• Sd – Sprinkler design factor

• W – Wind factor

• R – Tailwater reuse factor

• E – Emitter clogging factor

• T – Drip/micro irrigation design factor

3) The potential efficiency of the system – The system “potential efficiency" for an optimally performing unit for the site-specific physical layout can be determined from the National Irrigation Guide (NIG), Part 652, Florida Supplement, Chapter 15, Table FL15-1. For future conditions, a properly designed and installed system utilizing the latest technology is desired.

FIRI can be expressed as an equation to evaluate irrigation systems and water management. FIRI equals the potential efficiency times the system and management factors.

FIRI = PE X SYS X MGT

where:

PE = potential efficiency

SYS = (Wc)(Ce)(L)(R) for surface systems

= (Wc)(Ce)(C)(W)(R) for sprinkler systems

= (Wc)(Ce)(C)(W)(E)(T) for drip/microirrigation systems

= (Wc)(Ce)(C)(W)(E)(T) for drip/microirrigation systems MGT = (Md)(S)(I)(M)(D) (Sc)

A Microsoft (MS) Excel® worksheet titled “FIRI-FL” has been developed to perform the calculations required in the Farm Irrigation Rating Index. The FIRI-FL worksheet can be downloaded from available for download from the FOTG, Section I., C. References, 1. Engineering References, b.

Part 650, National Engineering Field Handbook – Florida Supplement, Chapter 20 – Engineering Software, at the following web address: http://efotg.sc.egov.usda.gov/treemenuFS.aspx .

In 2021 the form name was changed to the Farm Irrigation Rating Method – Florida (FIRM-FL) and some minor revisions were made to it. An example of that FIRM-FL form can be found in the Resources chapter of this document.

SECTION 4 – EVALUATION OF MICROIRRIGATION SYSTEMS

The procedure for evaluating microirrigation (drip or microjet) systems is presented in the NRCS NEH, Part 652, Irrigation, Guide, Chapter 9 (Pages 9-163 to 9-173) and the FL NRCS approved microirreval.xls computer program. The microirrigation evaluation (Micro-Eval) program uses the procedure in the NEH, performs the calculations, compiles a report, and available for download from the FOTG, Section I., C. References, 1. Engineering References, b. Part 650, National Engineering Field Handbook – Florida Supplement, Chapter 20 – Engineering Software, at the following web address: http://efotg.sc.egov.usda.gov/treemenuFS.aspx.

Equipment Required

The equipment required for the field evaluation:

1) 50 ft. tape measure or measuring wheel.

2) Pressure gauges (0-60psi) with fittings.

3) Stopwatch.

4) Graduated cylinder (100 to 1000 ml capacity).

5) 6 ft. soil auger.

6) Manufacturer’s emitter performance charts showing the relationship between discharge and pressure plus recommended operating pressures and filter requirements.

7) Blank microirrigation evaluation worksheets.

8) Portable flow meter.

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Field Procedure

The following is a description of the field procedure for evaluating microirrigation (drip or microjet) systems.

9) Start the system and let the pressure stabilize (5-10 minutes).

10) Determine if the irrigation system is operating under normal/typical conditions. If the irrigation system is operating under normal/typical conditions, immediately inform the irrigator and reschedule the field evaluation for a future date.

11) Record soil, crop, pump readings (rpm, psi, etc.), and irrigation system data on worksheet printed from Micro-Eval Excel workbook.

12) Check and note the pressure at the inlet and outlet of the filter. On average, there should be no more than 5 psi loss from the inlet end to the outlet end of the filter.

13) Determine from the irrigation decision maker, the frequency and duration of irrigation events he/she currently schedules for the crop.

14) Measure and record the minimum lateral inlet pressure (MLIP) of all the operating manifolds. The MLIP is the lowest pressure in all laterals served by one manifold, measured at the lateral inlet. For level or uphill manifolds, the MLIP is at the far end of the manifold. For downhill manifolds, the MLIP is often at about two-thirds the distance down the manifold. With manifolds on undulating terrain, MLIP generally is located on a knoll or high point. Record these readings on the field sheet or on a drawing for complex irrigation systems.

15) Measure the discharge (for thirty (30) seconds for microjets-sprayers or sixty (60) seconds for drippers) of sixteen (16) emitters, on four (4) laterals on the operating manifold.

16) Enter the amount in milliliters collected on the worksheet. A and B readings may be made at two adjacent emitters if two or more emitters serve one (1) plant. The worksheet is arranged such that the manifold is horizontal across the top of the page, with the pump end on the left. The laterals are vertical, with the top reading being next to the manifold.

17) Measure the inlet and end pressure of the laterals.

18) Measure the wetted area per plant, canopy area, and plant spacing. Use a soil probe, auger, or shovel to estimate the extent (depth) of the wetted area.

Calculations

The low quarter (¼) is lowest four gph measurements, regardless of location.

A discharge correction factor (DCF) is required since the overall system average pressure may be different than the pressure in the manifold where the flow measurements were made. The DCF is a factor to calculate the system average emitter discharge rate from the test manifold average emitter discharge rate.

Where TR = Transpiration ratio, NEH Part 623, Chapter 7, Table 7-15. This ratio estimates losses due to untimely rainfall and variations in the soil.

LRt = Leaching requirement ratio, NEH Part 623, Chapter 7, Equations 7-22 and 7-23. NEH

Part 623, Chapter 7, Figure 7-75 provides a graphical solution for Equations 7-22 and

7-23. This is to be considered if harmful soluble salts need to be removed from the root zone.

Analysis of Evaluation Results

The level of performance of microirrigation systems is indicated by the potential and application efficiency. A low potential efficiency indicates physical problems with the system, while low application efficiency indicates inaccurate scheduling. It is an economic decision whether the level of performance of a system is acceptable or whether improvements should be made.

If the level of performance is not acceptable, then the cause of the low efficiency must be determined. Through the evaluation process and detailed note keeping, the problems with the system can be identified. Florida NRCS conservation practice standards Irrigation System, Microirrigation, Code 441 and Irrigation Pipeline, Code 430 establishes a basis for comparison and help identify less than acceptable system components.

The main factor that determines system performance is emitter discharge rate variation throughout the system. NRCS specifications allow no more than a twenty (20) percent variation of the design flow rate. Since flow rates are dependent on pressure, pressure variation will affect performance.

Pressure should not vary more than 30% throughout the system. The following table lists specific test results, possible problems and possible solutions.

Typical Problems and Recommendations for Microirrigation Systems

Table 2 – Test Results, Problems, and Solutions for Microirrigation Systems

Test Problems Solution

Pressure at pump

Low pressure Check pump specifications

< 30 psi Change pump

Small wetted area Use smaller jets

Clogging Use smaller zones

Elevation effects Use higher rpm

High pressure Use larger jets

Low fuel efficiency Use larger zones caused by clogging Use pressure regulators

Filter inlet/outlet pressure > 5psi difference Clean or replace filter

Pressure between pump and first manifold (deadhead)

> 5psi difference

Use larger pipeline

Rezone

Increase rpm

Check valves

Pressure between manifolds

> 2-3 psi difference

Rezone

Control with valves

Use larger pipe

Pressure between laterals

> 2-3 psi difference Use additional manifolds

Use pressure regulators

Pressure variation in lateral

> 2-3 psi difference

Use additional manifolds

Use smaller emitters

Use higher pressure if elevation change

Use larger tubing

Emission Uniformity < 90% Use same brand and type of emitter

Clean emitters

The following list describes typical microirrigation system problems and possible solutions.

19) Low System Pressure – The overall pressure found in the system is lower than normally used in this type of system. The pressure could be increased by irrigating smaller or fewer zones at one time or by increasing pump rpm.

20) Filter Clogged – The pressure loss was higher than normally seen for this type of filter. The filter should be flushed, and the screen cleaned. If cleaning the filter does not reduce the pressure loss, then check the pressure gauges for accuracy and install a higher capacity filter if necessary. Screen filters usually have no more than 5 psi loss between the inlet and outlet.

21) Mainline Pressure Loss – Excessive pressure losses were found in the mainline. This reduces efficiency, since a higher pumping head is required to deliver adequate pressure to the emitters. Possible solutions are to divide the flow between mainlines by changing the zones that are operated at one time or to install additional mainlines.

22) Different Pressures between Manifolds – The average pressure varied between the submains.

Adjustable field valves should be installed, or existing valves should be used to equalize pressure between submains to make pressure and flow more uniform throughout the system.

23) Poor Emission Uniformity – Poor emission uniformity reduces the system efficiency since some of the trees will receive insufficient water while some will be over-irrigated. Emission uniformity is especially important if fertigation is being used. Excellent uniformity would be 90% or above.

24) Clogged Emitters – Many emitters were clogged, especially at the ends of the lateral lines.

Clogging can be reduced by flushing the laterals more often, or in severe cases, injecting chlorine, with the injection program based on sulphide and iron concentrations and pH.

25) Mixed Emitters – Emitters with differing discharge rates are being used. The system design should be reviewed to determine the correct discharge rate and number of emitters to use. It is important to use the correct emitter to allow good pressure and flow distribution for a particular pipe design. It is usually good to use one model of emitter throughout the system, since different models and makes could have different flow rates.

26) Poor Emitter Uniformity – A variation was found in the discharge rate between emitters operating at the same pressure. This is caused by variation in the emitters themselves. If this variation is unacceptable then the emitters should be replaced with new emitters of uniform operating characteristics.

27) Broken Pipes – Cuts and breaks were found in the lateral lines. Even small leaks can significantly reduce pressure in downstream sections. Repairing breaks will improve discharge uniformity and increase overall pressure.

28) Valves Not Opening – It appears that the control valves are not opening completely. A pressure differential was found upstream and downstream from the valves.

29) Pressure Regulators Not Functioning – The pressure regulators are not maintaining the downstream pressures within a satisfactory range. This is caused by some regulators malfunctioning or not having the required inlet pressure.

30) Submain Pressure Loss – Pressure was lost in the submains due to inadequate pipe size. The system design should be checked to determine the most practical way to reduce losses.

Alternatives include using smaller emitters to reduce flow, installing more submains or using pressure regulators.

31) Lateral Pressure Loss – The tubing is improperly sized for the number and size of emitters that are being used, causing an excessive loss of pressure near the end of the tube. The system design should be checked to determine the best alternative for reducing losses. Possibilities include using larger tubing, lower discharge emitters or additional submains.

32) Elevation Effects – Pressures and discharge rates varied due to differences in elevation. The system design should be checked to determine the best way to compensate for elevation and to equalize pressure. Alternatives include using pressure regulators or gate valves to reduce pressure in higher pressure areas and installing additional submains to increase pressure in lower pressure areas.

33) Small Irrigated Area – A small percentage of the field area was covered by irrigation. When a small area of soil is available to hold irrigation water, frequent, short irrigations are required.

With extremely small, wetted areas, the soil in this area may not be able to hold sufficient water to meet the crops needs. By installing emitters with a larger area of coverage, longer operating times could be used, the times between irrigations could be increased and the water will be more readily available to the crop. It is recommended that at least 33% of the field area be covered. If drip system is to be converted to a spray jet system, a complete redesign is necessary.

34) Emitter Integrity – Worn or missing emitters can greatly reduce the efficiency of an irrigation system. With worn emitters, they may not be able to provide the required flow rate for plant survival or they do not work at all. Missing emitters on the other hand may provide too much water which can lead to plant damage or disease. By installing new emitters, the survival rates for the plants should be improved. When replacing emitters, it is not recommended to not mix and match emitter types as this too could lead to a less efficient irrigation system.

SECTION 5 - EVALUATION OF SPRINKLER IRRIGATION SYSTEMS

The evaluation of sprinkler systems is based on a test of the pressure throughout the system and a measurement of the uniformity with which the water is distributed over the field surface.

The recommended procedure for evaluating sprinkler irrigation (center pivot, lateral move, traveling gun, periodic move or solid set) systems is presented in the NRCS NEH, Part 652, Irrigation Guide, Chapter 9 (Pages 9-119 to 9-162).

SECTION 6 - EVALUATION OF FIXED AND PORTABLE LATERAL SPRINKLER SYSTEMS

(SOLID SET AND LINEAR MOVE)

The FL NRCS solid set evaluation (SPR-SS-Eval) program (spr-ss-eval_ver_1.1.xls) uses the procedure in the NEH, performs the calculations, compiles a report, and is available for download from the FOTG, Section I., C. References, 1. Engineering References, b. Part 650, National Engineering Field Handbook – Florida Supplement, Chapter 20 – Engineering Software, at the following web address: http://efotg.sc.egov.usda.gov/treemenuFS.aspx.

The equipment required for the field evaluation:

1) Pressure gauge (0-100 psi) with pitot tube attached.

2) Stopwatch.

3) A large container of known volume clearly marked (1 gallon or larger).

4) A 4-ft hose having a diameter appreciably larger than the outside diameter of nozzles.

5) Catch containers.

6) 500 ml graduated cylinder to measure volume of water caught in containers.

7) Soil probe.

8) Shovel.

9) 100-ft tape measure.

10) Wind velocity gauge.

11) Raincoat, rubber boots.

12) Manufacturer’s sprinkler performance charts, when made available by irrigator or irrigation vendor and when irrigator has received government cost share.

13) Set of drill bits.

The following is a description of the field procedure for evaluating fixed solid set and portable lateral sprinkler systems.

14) Select the field location for the evaluation. Field location should be a location at which the pipe pressure is representative of the entire system. If the pipe diameter is the same throughout the entire lateral, about half the pressure loss resulting from pipeline friction loss in that lateral occurs in the first 20 percent of the length. Over 80 percent of pressure loss occurs in the first half of the lateral length. On a flat field, the most representative pressure occurs about 30 to 40 percent of the distance from the lateral inlet to the terminal end.

15) Measure and record sprinkler spacing.

16) Obtain and record duration and frequency of irrigation from operator.

17) Record Management Allowable Depletion (MAD) as described in the NEH, Part 652, Irrigation

Guide, Florida Supplement, Chapter 4, Water Requirements, if available.

18) Locate catch containers as shown in Figures 4a and 4b. The containers should be evenly spaced between two adjacent laterals for solid set systems. Any surrounding vegetation that would interfere with a container should be removed.

Figure 4a – Example Solid Set Catch Can Layout

Spacing catch cans: Divide sprinkler spacing by number of cans (row or column). If the answer is a whole number, this will be the spacing between cans. One-half of this number will be the spacing between the sprinkler and the first can.

If the answer is not a whole number, round down for can spacing and divide the remaining length in half, for spacing between the sprinkler and first can. For example, if spacing is 34 feet and there will be 5 rows of cans, 34/5 = 6.8. Spacing between cans will be 6 feet. Spacing between the cans is 34 feet minus the sum of the spacings between cans (24 feet in this case) = 10 feet.

Divide the 10 feet by 2 to determine the spacing between the sprinkler and the first can (10/2 = 5 feet).

Figure 4b – Example Solid Set Catch Can Layout

19) Check and record make and model of sprinklers and diameter of nozzles.

20) Record rated sprinkler discharge, pressure and design application rate from manufacturer’s charts.

21) Check and record the size and slope of lateral lines and the height of risers.

22) Temporarily turn sprinklers that will irrigate the catchment area, away from catchment area. To do so, block sprinklers by wedging a short piece of wire or stick behind the swinging arm.

23) Set a known amount of water (in the same type of container as the catch containers) outside the catchment area to measure the approximate volume of water lost to evaporation.

24) Turn on water to fill lateral lines.

25) Measure pressure and discharge rates at sprinklers that are going to irrigate the catchment area.

26) Remove wire or stick from sprinklers that are going to irrigate the catchment area and start test time.

27) While test is in progress, measure pressure and discharge rates at random sprinklers within the system.

28) Note wind speed and direction.

29) Operate the system long enough to catch a measurable amount of water. End test and record time.

30) Measure and record catch volumes.

31) Measure and record evaporation.

The Sprinkler Irrigation System Evaluation Form can be found in the NRCS Irrigation Guide, Chapter 15, pages 15-73 to 15-78. The form is set up for transposing catch data. Adjustments in computations are required if data are not transposed when adjacent laterals are operating.

Calculations

32) Convert volumes of water caught to rates (in./hr.).

After performing the catch can test, the average catch is calculated by adding the amount caught in all containers and dividing by the number of containers. The amount of evaporation is added to this average and the result is divided by the catch can conversion factor to give the average catch rate.

33) Compute and evaluate Distribution Uniformity (DU) and Christiansen’s Uniformity (CU) coefficient.

34) Determine system DU and CU.

Where:

Px = the maximum sprinkler pressure (psi) Pn

= the minimum sprinkler pressure (psi) Pa = the average sprinkler pressure (psi)

35) Calculate gross application rate per test.

If a flow meter is present in the system, the average sprinkler discharge rate can also be determined by dividing the total system flow rate by the number of sprinklers.

Re = Effective portion of applied water to ground

SECTION 7 - EVALUATION OF TRAVELING GUN SPRINKLER SYSTEMS

1) Catch containers and stakes.

2) 50 ft. measuring tape.

3) 500 ml graduated cylinder.

4) Pressure gauge (0-160 psi).

5) Inside diameter measurement calipers.

6) Soil auger, push tube sampler, probe, shovel.

7) Stopwatch.

8) Wind velocity gauge.

9) Thermometer to measure air temperature.

10) Manufacturer’s sprinkler head performance charts, when made available by irrigator or irrigation vendor and when irrigator has received government cost share.

The following is a description of the field procedure for evaluating traveling gun sprinkler systems.

11) When available obtain sprinkler gun specifications from the manufacturer, including operating pressures, nozzle type, inside diameter of nozzle, and system speed.

12) Record system information including the condition of the unit, operating pressure at pump and nozzle, the size of the nozzle, and the crop(s) being irrigated.

13) Record size and length of hose.

14) Record the make and model of the sprinkler.

15) Record the make and model of the traveler.

16) Document any wet/dry areas in the field.

17) Document any erosion or runoff.

18) Record the size of risers and pipe.

19) Estimate soil water deficit in field, both ahead of and behind traveler.

20) Note depth to water table, apparent root development, and any root and water movement restriction.

21) Select evaluation site that is representative of field and ahead of traveler.

22) Measure system flow rate at the beginning and end of the evaluation.

23) Observe system operating pressure from the ground. Do not climb up unit while operating.

The Sprinkler Irrigation System Evaluation Form can be found in the NRCS Irrigation Guide, Chapter 15, pages 15-89 to 15-93. A fillable version of the Sprinkler Irrigation System Evaluation Form can be for download from the FOTG, Section I., C. References, 1. Engineering References, b. Part 650, National Engineering Field Handbook – Florida Supplement, Chapter 20 – Engineering Software, at the following web address: http://efotg.sc.egov.usda.gov/treemenuFS.aspx.

SECTION 8 - EVALUATION OF CENTER PIVOT SPRINKLER SYSTEMS

24) Catch containers and stakes

25) 300 ft. measuring tape.

26) 500 ml graduated cylinder.

27) Pocket tape (inches).

28) Diameter tape.

29) Pressure gauge with pitot tube (0-100 psi).

30) Flow measuring device.

31) Ohmmeter or electrical ground check meter to measure salinity.

32) Soil auger, push tube sampler, probe, shovel.

33) Equipment for determining soil moisture.

34) Stopwatch.

35) Thermometer to measure air temperature.

36) Wind velocity gauge.

37) Ladder.

38) Raincoat, rubber boots.

39) When available, obtain printout of manufacturer’s pivot design (for use in field and office).

The following is a description of the field procedure for evaluating center pivot sprinkler systems.

40) Select an evaluation site that is representative of the field.

41) Obtain end gun specifications from the manufacturer, including model and capacity.

42) Obtain a certified copy of sprinkler package from the irrigator or irrigation designer and verify sprinklers have been installed as specified in the sprinkler package.

43) The system pressure shall match pressure used to design the sprinkler package.

44) The end gun shall be operated in the same operational mode as specified in the sprinkler package.

45) Record system information including the condition of the unit and the crop(s) being irrigated.

46) Determine flow into system. If ultrasonic flow meters are used, ensure the pipeline is flowing full at the location of the meter and that there is adequate distance of straight pipe, free of obstructions, upstream from the point of flow measurement.

47) Determine operating pressure at the beginning of the system.

48) Record wind speed and direction, and air temperature.

49) Set catch containers along radius from pivot at a spacing of ≤30 feet. Omit placing them under the first one or two spans. Level the containers. Extend the containers beyond the wetted area. Avoid the tower wheels.

50) Set a known amount of water (in the same type of container as the catch containers) outside the catchment area, to measure the approximate volume of water lost to evaporation.

51) Allow the wetted area to completely pass over the catch containers.

52) Measure water caught in the catch containers.

53) Reference the evaporation lost in the evaporation containers.

54) Weight the catches.

The Sprinkler Irrigation System Evaluation Form can be found in the (NEH) Part 652, Irrigation Guide, Florida Supplement, Chapter 15, pages 15-81 to 15-88. The form is set up for transposing catch data. Adjustments in computations are required if data are not transposed when adjacent laterals are operating. A fillable version of the Sprinkler Irrigation System Evaluation Form can be for download from the FOTG, Section I., C. References, 1. Engineering References, b. Part 650, National Engineering Field Handbook – Florida Supplement, Chapter 20 – Engineering Software, at the following web address: http://efotg.sc.egov.usda.gov/treemenuFS.aspx.

Analysis of Sprinkler System Evaluations (Solid Set, Linear Move, Traveling Gun, and Center Pivot)

The level of performance of sprinkler systems is indicated by the potential efficiency and application efficiency. A low potential efficiency indicates physical problems with the system, while low application efficiency indicates inaccurate scheduling. Ultimately, it is an economic decision whether the level of performance of a system is acceptable or whether improvements should be made.

If the level of performance is not acceptable, then the cause of the low efficiency must be determined. Through the evaluation process and detailed note keeping, the problems with the system can be identified. Florida NRCS conservation practice standards Sprinkler System, Code 442 and Irrigation Pipeline, Code 430 establish a basis for comparison and help identify less than acceptable system components.

The two (2) main factors that determine system performance are pressure variation and sprinkler spacing. NRCS specifications allow no more than a 20% variation in pressure among sprinklers, and a sprinkler spacing no more than 25% of the wetted diameter for fixed position spray sprinklers, 40% of the wetted diameter for rotating or oscillating sprinklers, and 50% of the wetted diameter for impact sprinklers. Base the wetted diameter on manufacturer’s information for the design nozzle height and pressure.

The average system pressure should be high enough to break up the water discharge stream, normally 40 psi or higher. For low pressure systems the average system pressure should be 40 psi or lower, unless specified by manufacturer. Nozzle sizes should be uniform throughout the system.

In small fields, partial circle nozzle heads may be used to adequately cover the edge of the field. In this case, application rates should be matched for the sprinklers. For example, 180-degree sprinklers should have one half (½) the discharge rate of the 360-degree sprinklers.

Typical Problems and Recommendations for Sprinkler Irrigation Systems Table 3

– Test Results, Problems and Solutions for Sprinkler Systems

Test Problems Solution

Pressure at pump

Low pressure Check pump specifications

< 40 psi

(poor coverage)

Change pump

Use smaller nozzles

Use smaller zones

Use higher rpm

High pressure Use larger nozzles

60 psi Use larger zones

Filter inlet/outlet pressure > 5 psi difference Clean or replace filter

Pressure between pump and first manifold

(deadhead)

> 10 psi difference

Use larger pipeline

Rezone

Increase RPM

Check valves

Pressure between submains

> 4-6 psi difference

Rezone

Control with valves

Use larger pipe

Pressure between laterals > 4-6 psi difference Use additional submains

Use pressure regulators

Pressure variation in lateral

> 4-6 psi

Use additional submains

Use smaller nozzles

Use pressure regulators

Sprinkler spacing > 65% of wetted diameter Increase pump rpm

Redesign system

Sprinkler discharge > 20% variation

Use same brand and type of sprinkler

Clean or replace nozzles

Clean screens

End gun

Out of adjustment or not operating

Adjust the end gun position or repair end gun

Boot Leak Repair boot leak

No booster pump Install booster pump

Distribution uniformity < 60%

Adjust sprinklers

Increase pressure

Change sprinkler type

Redesign system

Control box Malfunctioning Replace control box

The following list describes typical sprinkler system problems and possible solutions.

1) Low System Pressure – The overall pressure found in the system is lower than normally used in this type of system. To produce uniform coverage, sprinklers require high pressure to break up the discharged stream of water. The sprinkler manufacturer usually will provide a recommended pressure range for each sprinkler. Usually, the minimum pressure is 40 psi.

Increasing pressure could improve the spray pattern and the uniformity of coverage. The pressure could be increased by irrigating smaller or fewer zones at one time or by increasing pump rpm.

2) Filter Clogged – The pressure loss was higher than normally seen for this type of filter. The filter should be flushed, and the screen cleaned. If cleaning the filter does not reduce the pressure loss, then check the pressure gauges for accuracy and install a higher capacity filter if necessary. Screen filters usually have no more than 5 psi loss between the inlet and outlet.

3) Mainline Pressure Loss – Excessive pressure losses were found in the mainline. This reduces efficiency, since a higher pumping head is required to deliver adequate pressure to the sprinklers. Possible solutions are to divide the flow between mainlines by changing the zones that are operated at one time or to install additional mainlines.

4) Different Pressures Between Manifolds – The average pressure varied between the manifolds/submains. Valves should be installed, or existing valves should be used to equalize pressure between manifolds/submains to make pressure and flow more uniform throughout the system.

5) Wide Spacing – The sprinkler spacing is wide for the diameter of coverage of these sprinklers.

Sprinklers should have close to head-to-head coverage when pressure is correct. The system design should be reviewed to determine nozzle, pressure and spacing alternatives that would produce better spray pattern overlap.

6) Poor Distribution Uniformity – The distribution uniformity is a measurement of how uniformly the water is applied over the field surface. Poor distribution uniformity reduces the system efficiency since some of the plants will receive insufficient water while some will be over-irrigated. The uniformity should increase if the pressure is increased. Occasionally sprinklers will have poor uniformity even with adequate pressure and spacing. Check the sprinkler for adjustments.

7) Broken Sprinklers – Many sprinklers had broken arms or nozzles.

8) Mixed Nozzle Sizes – Nozzles with differing discharge rates are being used. The system design should be reviewed to determine the correct nozzle to use. It is important to use the correct nozzle to allow good pressure and flow distribution for a particular pipe design and to provide adequate spray pattern overlap. The nozzles should also be matched. All 360-degree sprinklers in a system should have the same nozzle size. 180-degree sprinklers should have a nozzle size to produce ½ of the 360-degree discharge rate. Check the original design and replace nozzles.

9) Poor Sprinkler Uniformity – A variation was found in the discharge rate between sprinklers operating at the same pressure. This is caused by variation in the sprinklers or nozzles themselves, possibly due to wear. If this variation is unacceptable then the sprinklers should be replaced with new sprinklers of uniform operating characteristics.

10) Broken Pipes – Breaks were found in the pipelines. Even small leaks can significantly reduce pressure in downstream sections. Repairing breaks will improve discharge uniformity and increase overall pressure.

11) Valves Not Opening – It appears that the control valves are not opening completely. A pressure differential was found upstream and downstream from the valves.

12) Pressure Regulators Not Functioning – The pressure regulators are not maintaining the downstream pressures within a satisfactory range. This is caused by some regulators malfunctioning or not having the required inlet pressure.

13) Submain Pressure Loss – Pressure was lost in the submains due to inadequate pipe size.

Pressure variation is sometimes caused by partially closed valves or clogging of the sprinkler screens. The system design should be checked to determine the most practical way to reduce losses. Alternatives include using smaller nozzles to reduce flow, installing more submains or using pressure regulators.

14) Lateral Pressure Loss - The lateral pipes are improperly sized for the number and size of sprinklers that are being used, causing an excessive loss of pressure near the end of the lateral. The system design should be checked to determine the best alternative for reducing losses. Possibilities include using lower discharge nozzles or additional submains.

15) Elevation Effects – Pressures and discharge rates varied due to differences in elevation. The system design should be checked to determine the best way to compensate for elevation and to equalize pressure. Alternatives include using pressure regulators or gate valves to reduce pressure in higher pressure areas and installing additional submains to increase pressure in lower pressure areas.

16) Blocked Sprinklers – Sprinkler performance will be affected if the sprinkler stream is blocked.

The sprinkler should be above the crop vegetation or should be a low-trajectory type if under-tree or in a greenhouse.

17) Clogged Sprinklers – The nozzles or screens in the sprinklers were clogged. Remove and clean the nozzle or screens. Check the water supply and install a filter if the water contains particles larger than the sprinkler nozzle.

18) Boot Leak – A Boot is approximately an 18-inch piece of flexible material connecting each tower to allow the pivot to flex with the terrain. If the boot is leaking, we recommend that they replace the boot.

19) Pipe Joint Leak – A section of the overhead pipe is connected, and each connection has a rubber gasket. If the pipe joint is leaking the gasket has to be replaced.

SECTION 9 - EVALUATION OF SUBIRRIGATION SYSTEMS (FLOW THROUGH AND

UNDERGROUND CONDUIT)

Successful operation of subirrigation systems requires that the water table be maintained at a uniform depth below the ground surface so that moisture can be supplied to plants through capillary movement (upward flux). The water table is regulated by controlling drainage to manage the removal of subsurface and surface water and by providing irrigation water as needed to maintain the water table high within an acceptable range to provide adequate moisture to the crop. A drainage system is essential to remove excess surface water and subsurface water, so that the water table does not remain in the root zone for long periods to cause crop damage.

Information gathered should include both management factors as well as irrigation system factors.

Management factors include whether water measurement devices are used (Md), method used to determine when to irrigate (S) (soil moisture monitoring and scheduling procedure), irrigation skill and action level (I), the condition of the system (M) (maintenance), the ability of the system to provide irrigation water when needed (D), soil condition (Sc). System factors include the type of conveyance system used (Wc), the capacity of the delivery system (D), land leveling factor (L), tailwater recovery systems (R), climatic factor (C), wind factor (W), sprinkler design factor (Sd), emitter clogging factor (E), and drip/microirrigation design factor (T).

These factors are discussed in detail in "Farm Irrigation Rating Index (FIRI)”, (NEH) Part 652, Irrigation Guide, Florida Supplement, Chapter, Chapter 15, FL652.1501. The FIRI worksheet can be downloaded the FOTG, Section I., C. References, 1. Engineering References, b. Part 650, NEH

– Florida Supplement, Chapter 20 – Engineering Software, at the following web address:

http://efotg.sc.egov.usda.gov/treemenuFS.aspx. The necessary data can be obtained by interviewing the irrigator and by making observations and measurements.

For subirrigation the key system components are conveyance, uniformity of water table, capacity to maintain the desirable water table, surface slope, and prevention of tailwater loss. A system “potential efficiency" above 75% is considered good for a subirrigation system. For future conditions, a properly designed and installed system utilizing the latest technology is desired.

This section describes how to perform and evaluate both general and detailed evaluations of subirrigation systems. It is recommended that detailed evaluations be performed to gain knowledge and experience of how subirrigation systems perform under different management techniques, soil types, crops, etc., and when time and equipment are available.

General field evaluations will normally be performed when information is available on the system and/or when time and equipment are not available. These evaluations are qualitative and often provide the necessary information for identifying and correcting problems of the system layout and of its operation.

Detailed field evaluations are quantitative and provide more detailed data required for recommending changes, for making economic comparisons, and for furnishing background data for design of systems operating under similar conditions.

The equipment required for the general field evaluation:

1) Soils auger for verifying soil type and installing water table wells (cased or uncased).

2) Stopwatch or watch with easily visible second hand for timing irrigation inflows and outflows.

3) Measuring tape to measure water table depth and furrow spacing.

4) Flow measurement equipment.

5) Soil moisture sensor.

6) Survey equipment for checking irrigation slope.

Equipment required for the detailed field evaluation includes the same equipment required for general evaluation plus:

1) Flow measuring devices such as small Parshall flumes, orifice plates, flow meters, large Parshall flumes, and/or calibrated containers. Devices must be capable of measuring head or recording velocity of flow.

2) Equipment for determining soil moisture may be desirable.

3) Stage recorders may be necessary.

4) Soil Moisture Sensor.

5) Cased observation wells.

The following describes information to be gathered for the field procedure for a general field evaluation.

1) Estimate water loss in the delivery system (if open ditches).

2) Determine or verify soil type. Include areas where irrigator has observed abnormal conditions.

3) Determine from irrigator and by observation, wet and dry locations in the field. (Points that wilt early and areas where plant’s response indicates wet areas).

4) Choose typical locations (furrows) in fields to be evaluated. A minimum of three (3) furrows shall be evaluated in a management zone. Locations shall include wet and dry points that contain a significant area (greater than 10 percent of the management zone).

5) During the irrigation cycle, record furrow inflow (gpm), length, slope, spacing, and depth.

6) Observe the runoff (tailwater) in furrows or mains and record observations. Estimate the rate, length of time, and amount of tailwater loss.

7) During the irrigation cycle, two (2) water table depths shall be measured at each location evaluated. The water table depth shall be recorded at points ¼ and ¾ along the furrow length, midway between the furrows. The measurements should be taken when the irrigation stream is at least midway along the furrow. Measure the elevation difference between the water table and the bottom of the furrow.

8) Observe drainage characteristics of the system. If inadequate, discuss with the irrigator.

9) Check erosion throughout the system (furrows, drainage mains and laterals).

10) Estimate total water available for irrigation.

Information to be gathered for the field procedure of a detailed field evaluation includes the same as for general field evaluation but may also include:

1) Actual measurement of water loss in delivery system or portions of the system.

2) During the irrigation cycle, record hourly water table response, i.e., depth and time to…