Illinois Administrative Code › Title 35 - ENVIRONMENTAL PROTECTION › Part 570 - DESIGN AND MAINTENANCE CRITERIA REGARDING RUNOFF FIELD APPLICATION SYSTEMS › Subpart B - DESIGN CRITERIA › Appendix J - Sample Design Problem

Current through Register Vol. 48, No. 28, July 12, 2024
A livestock producer had 300 head of feeder cattle on a
				  concrete feedlot (see Figure 1) and wanted to install a runoff field
				  application system to control feedlot runoff which entered a nearby stream. The
				  facility met the Conditions for System Utilization set forth in Section 570.202
				  and the runoff field application system was designed by following the procedure
				  in Appendix A.
1. Site Specific Data
A. From Figure 1 and Appendix B:
Concrete Feedlot Area
20,038 sft. (0.46 acres)
Roof Area
4,792 sft. (0.11 acres)
All other drainage was diverted from the feedlot
				  and field application area with gutters, curbs, and berms.
B. From the procedure in Appendix D, the slope of
				  the field application area was 1.0%.
C. From the Soil Survey for the county the soil
				  infiltration rate (SI) of the field application area was 2.0 inches/hour using
				  the procedure in Appendix C (#3).
2. From Appendix B, runoff volume was calculated.
Roof
4,785 sft. x 0.1408
=
673.7 cft.
Feedlot
20,037 sft. x 0.0991
=
1985.7 cft.
Design Runoff Volume (VR)
=
2660 cft.
From Appendix B, the total drainage area was
				  calculated.
20,037 + 4,785
=
24,822 square feet
3. Settling Basin Design
The total settling basin volume was calculated as
				  provided in Section 570.204(a)(1).
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				  image
From Appendix I, the settling basin dimensions
				  were calculated after choosing 3 feet settling basin height (h), 12 feet width
				  (b), and 15:1 slope.
L1
=
3 x 15
=
45 feet
V1
=
(1/2) (12 x 3 x 45)
=
810 cft.
V2
=
1229 - 810
=
419 cft.
L2
=
419 / (12 x 3)
=
11 feet, 8 inches
Round-off L2 to 12
							 feet.
Foundation drainage tiles were not needed as the
				  soil survey indicated the groundwater table did not rise above 5 ft.
				  depth.
A 24-inch diameter riser pipe was provided
				  pursuant to Section 570.204 (5) and concrete was chosen as the settling basin
				  construction material.
4. Field Application Area Design
The field application area was calculated using
				  Section 570.204(e)(4).
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				  image
Appendix E was used to determine the dimensions of
				  the field application area using the next larger sized area of 14,875
				  sft.
Slope
1.0%
Length
425 feet
Width
35 feet
FAA
14,875 sft. (0.34 acres)
5. Calculate Flow onto Field Application Area
The flow onto the field application area was
				  determined using Appendix G as being approximately 40 gpm.
A more accurate calculation was made as
				  follows:
Qf
=
(0.0026)
x
FAA
Qf
=
(0.0026)
x
14,875 sft.
=
38.7 gpm
6. Effluent Transport System Design
A pipe was chosen to transport the settling basin
				  effluent to the distribution manifold and was designed using Appendix F at the
				  179 gpm criteria (since this pipe design could handle 38.7 gpm).
Slope 0.5%
PVC non-perforated pipe
Diameter of pipe - 6 inches
7. Junction Box Design
A junction box was constructed to the
				  specifications provided in Appendix H.
Adjustable slots were included in the drop boxes
				  to compensate for frost heaving of the junction box in the future.
8. Distribution Manifold Design
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				  image
An 8-inch diameter PVC pipe (17 feet long) was
				  purchased and cut in half down the pipe length to provide 2 manifolds each
				  4-inches deep. Each manifold had 6 inches removed to provide the required
				  length of 16.5 feet.
Tin snips were used to cut V-notch weirs 12 inches
				  apart on center on one side of each manifold with each notch cut 1.5 inches
				  wide and 2.5 inches deep.
The two distribution manifolds were placed in the
				  previously installed junction box (the junction box was located in the center
				  of the field application area width). Caps were provided over the outside end
				  of each distribution manifold and 1/8- inch wire staples were used to anchor
				  each manifold at 5 foot spacings.
A 1-foot wide pea gravel splash apron was provided
				  below the V-notch weirs over the length of each manifold.
Figure 1: Sample Design Problem
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				  image