Field Procedures for Determining Irrigated Acres

1
Field Procedures for Determining Irrigated Acres
Prepared by

• Robert Evans
• Ron Sheffield
• Karl Shaffer
• Jonathan Smith

2
Background

• Lack of Irrigation System Specificity in many
  CAWMP
• Moving to General Permits
• Consistency, minimum irrigation specifications
  need to be included in CAWMP
• CAWMP must clearly indicate Irrigated Acreage

3
Irrigation System Performance

• Irrigation Calibrations
• Conducted by NC CES
• Many types of systems
• Over 50 were found not to be operating at
  desired or designed conditions
• Operating pressure generally too low resulting in
• Deficient wetted radius
• uneven application at rates higher than allowed
  by CAWMP
• Poor system design or installation
• Improper equipment operation

4
Irrigation System Performance

• General Observation from calibration testWetted
  diameter (radius) was consistently only 90
  percent of the value published in manufacturers
  charts
• Consequence Many systems do not have adequate
  overlap even when operated at design pressure

5
Average Performance of Properly Adjusted and
Operated Systems
100
78 of radius 50 of volume
Application Depth, of target depth
90 of radius 18 of volume
Measured Distance from Gun or Sprinkler, of
wetted radius
6
SB-1217 Interagency Committee

• Determined that CAWMP must clearly indicate
  Irrigated Acreage
• Adopted the term CAWMP Wettable Acreas the
  irrigated acreage allowed to be counted towards
  fulfilling the minimum acreage requirement for
  proper nutrient utilization as specified in the
  CAWMP

7
SB-1217 Interagency Committee

• Defined two broad categories for determining the
  CAWMP Wettable Acre based on when the irrigation
  system was installed
• Existing Irrigation System
• New or Expanded Irrigation System
• Adopted minimum irrigation system standards for
  each category and established procedures for
  computing the CAWMP Wettable Acre

8
SB-1217 Interagency Committee

• Considered recommendations from
• irrigation engineers
• certified irrigation designers
• irrigation industry representatives
• animal production industry
• Irrigated acreage determined by the procedures is
  intended to reasonably and practically account
  for physical limitations of the application
  equipment

9
SB-1217 Interagency Committee
Minimum design standards established for
Existing Irrigation Systems

• Stationary Sprinklers
• Spacing between 50 and 70 percent of field
  verified wetted diameter
• Traveling Guns
• Lane Spacing between 60 and 90 percent of field
  verified wetted diameter

10
Irrigated Acreage

• Existing Irrigation Systems that satisfy Minimum
  Recommended Design Standards
• Multiple Laterals
• Irrigated Acreage Net Wetted Area
• Single Lateral
• Irrigated Acreage 90 Wetted Diameter

11
Irrigated Acreage

• Other Existing, New, Expanded Systems
• Irrigated Acreage Effective Design Area
• Effective Design Area is that area that receives
  at least 50 of the target application volume
  (78 of wetted radius)

12
Design Standards for Existing Systems - CAWMP

• Stationary SprinklersSpacing based on 50 to 70
  percent of manufacturers published wetted
  diameter
• Traveling GunsLane spacing based on 60 to 90
  percent of manufacturers published wetted
  diameter

13
WA Targeted Implementation

• CAWMP reviewed by DWQ or DSWC to determine
  compliance with SB1217 Wettable Acre Definitions
  Specifications
• Farms failing initial review receive written
  notification from DWQ that WA determination
  required for farm
• WA determination must be completed within 6
  months of notification from DWQ

14
Likely candidates for WA determination

• Farms that received a N.O.V. within past two
  years - especially for irrigation/application
  violations
• CAWMP without adequate maps depicting irrigation
  system layout
• Farms with obvious field limitations(ditches,
  small fields, lack of buffers)
• Farms where CAWMP credits more than 75 of the
  total acreage in a field
• Farms with portable systems

15
WA Determination Exemptions

• Adequate irrigation design with maps depicting WA
  signed by I or PE
• Adequate D1 and D2/D3 irrigation sheets with maps
  depicting WA signed by I or PE
• Adequate D1 irrigation sheet with map depicting
  wettable acres signed by WUP
• Farm that satisfy 75 rule (no field credited
  with more than 75 of total acreage in the
  field)

16
Determination of Irrigated Acreage

• Determination of Wetted Diameter
• System Map
• Field Verification
• Direct Measurement
• Footprint measurement
• Verification of sprinkler operating pressure

17
Irrigation System Map Requirements

• Scaled map or scaled-aerial photograph
• Location of system components
• pump, intake, main valves, pipe network
• location of hydrants travel lanes
• length and width
• location of sprinklers
• type of equipment
• Location of buffers
• (wells, streams, property lines, roads, etc.)

18
Irrigation System Map Requirements

• Minimum scale
• 1 inch 200 feet stationary, 1 inch 400 feet
  traveler
• Suitable Maps
• FSA (clean original precisely blown up
  reproduced)
• Aerial photo with ground trued scale
• County tax map
• Survey map with total station/GPS
• GIS map
• USGS 7.5o quadrangle precisely blown up

19
Stationary Sprinkler SystemField data
requirements (See Worksheet)

• Sprinkler make and model number
• Sprinkler nozzle size
• Lateral spacing sprinkler spacing along lateral
• Operating pressure at the sprinkler
• Sprinkler wetted diameter (measured or chart)
• Number of sprinklers to be operated at one time
• Total number of sprinklers/sprinkler locations
• Exterior sprinklers full circle part circle
• Interior Sprinklers full circle
• Sprinkler locations permanently marked (yes or
  no)
• Supply line Permanent pipe or Portable pipe

20
Collection of Field DataGeneral Procedures -
Stationary Sprinkler

• Conduct field inspection
• Determine system status(Existing or new)
• Number of Interior and Exterior Sprinklers
• Measure Lateral and sprinkler spacing
• Measure operating pressure at sprinkler and
  wetted diameter with system operating
• Determine Lateral and Sprinkler
  Pattern(Multiple, Single, Irregular)

21
Existing Irrigation system
22
Interior Sprinkler receives overlap from four
adjacent sprinklers along perpendicular transects
Exterior Sprinkler
Lateral Spacing
Spacing Along Lateral
23
Pressure gauge on riser pipe
24
Pressure gauge at pump
25
Test wetted diameter -1/4 to 1/2 the length of
the lateral
Multiple LateralsStationary sprinkler
To Pump
26
E
Multiple LateralsStationary sprinkler
To Pump
Lateral Pattern
27
Lateral Pattern Lateral Pattern
Lateral Pattern
Drainage Outlet
To Pump
Single Lateral Stationary Sprinkler
28
Irregular spacing greater than 70 percent of
wetted diameter
To Pump
29
Determining the Wetted Radius
After 4 or 5 passes, Flag to mark edge of wetted
radius (ignore any unusual throws)
Wetted Radius average distance from sprinkler
to 4 flags
Diameter twice radius
30
Calculating Wetted Diameter

• Calculate the average radius
• example 65 60 68 62 255 ft
• 255 / 4 63.74 64 ft
• Double the radius to reflect the wetted diameter
• example 65 x 2 128 ft

31
Stationary Sprinkler SystemWA computational
worksheet

• Farm and field identification John Doe F-158A
• Irrigation system designation x
  Existing ___New
• Sprinklers 42 interior 30
  exterior
• Wetted diameter (WD) 127 feet
• Spacing 80 lateral/sprinkler 63 percent WD
• Pattern x multiple _____single ____irregular
• 0.129 acres/interior (T3-Col B) X 42 interior
  4.95 acres 0.165 acres/exterior (T3-Col
  C) X 30 interior 5.42 acres
• 4.95 acres interior 5.42 acres exterior 10.37
  Wettable Acres
• Technical Specialist Date
  5-25-99

32
CAWMP Wettable Acre Determination
Irrigation System Status
New/Expanded
Existing
Multiple Laterals
Multiple Laterals lt70 of wetted Diameter
Yes
No
No
Yes
Table 1-5 Cols D E
Table 1-5 Col. G
Sprinkler Spacing Along Lateral lt70 of
Wetted Diameter
Sprinkler Spacing Along Lateral lt70 of
Wetted Diameter
No
Yes
Yes
No
Excessively Spaced Sprinklers Table 6 Col. G
Single Lateral Table 1-5 Col. F
Multiple Lateral Table 1-5 Cols B C
33
Existing Traveler Irrigation System
34
Traveling Gun Irrigation SystemField data
requirements (See Worksheet)

• System make and model number ________________
• Hose length ___feet and hose inside diameter
  ___inches
• Gun make and model number ______________
• Gun nozzle size __inches __ring orifice
  __ taper bore orifice
• Gun arc angle ___degrees
• Travel Lane spacing ____feet (___uniform or
  ___random) ___ Exterior hydrants ___
  Interior hydrants
• Operating pressure at the gun ___psi
• Gun wetted diameter ____feet (___measured or
  ___chart)
• Supply line ___Permanent pipe or ___Portable pipe

35
Collection of Field DataGeneral Procedures -
Traveling Gun

• Conduct field inspection
• Determine system status(Existing or new)
• Number of Interior and Exterior Travel Lanes
• Measure Lane spacing
• Measure operating pressure at gun and wetted
  diameter with system operating
• Determine System Pattern(Multiple or Single Lane)

36
Travel Lane Spacing
Gun Travel Distance
37
Use pressure gauge on the gun to verify operating
pressure
38
Good droplet breakup and uniformity with proper
operating pressure
39
Operating pressure too low results in improper
breakup of stream and poor uniformity
40
Gauges on reel elbows do not indicate the
operating pressure at the gun
41
Inspect nozzles and rings for proper size and
wear. Use calipers to measure rings.
42
Observe 4 or 5 passes and Flag the average
(Ignore unusual throws caused by wind gust)
43
0.9r
0.9r
330 (typical)
Travel Lane Pattern
To drainage outlet
To Pump
44
Traveling Gun SystemWA computational worksheet

• Farm and field identification John Doe F-158A
• Irrigation system designation x
  Existing ___New
• Number of Travel Lanes 1 interior 2
  exterior
• Wetted diameter (WD) 290 feet Gun angle 315
  degrees
• Travel lane length 820 feet
• Lane spacing 220 feet 75.9 percent WD
• Pattern x multiple _____single
• Compute Wettable acres per lane x interior
  exterior
• 0.65 acres Start end of pull from Table EI75
  Col B
• 4.14 acres Middle portion of pull (220 x 820 /
  43560/ac)
• 0.46 acres Stop end of pull from Table EI75 Col
  F
• 5.25 Wettable Acres
• Technical Specialist Date 5-25-99
  

45
CAWMP Wettable Acre Determination
Irrigation System Status
Existing
New/Expanded
Multiple Travel Lanes lt90 of Wetted diameter
Multiple Travel Lanes
No
Yes
Yes
No
Table N75
Table NE60-NE75 or Table NI60-NI75
Tables EE60-EE90 or Tables EI60-EI90
Table E90
46
Determining Irrigated AreaSummary of Steps

• Create Map
• Collect field data and complete field worksheet
• Provide field worksheet to Technical Specialist
• Need WA or I certification, or PE
• Trained to calculate Wettable Acres and make
  technical recommendations
• Complete Computational Worksheet (Refer to,
  and follow
• AG-553-6, Stationary Sprinkler Systems
• AG-553-7, Hard Hose Traveler Systems)
• Computational Worksheet must be signed by WA, I
  or PE

47
What if you find out you need more acreage?

• Re-measure Wetted Diameter in field
• Re-visit your Waste Utilization Plan (WUP)
• correct number of animals, average crop yields,
  lagoon analysis
• change crop species or add winter annuals
• Expand existing or install additional application
  sites
• Change production system or reduce herd size

48
(No Transcript)