Estimating the volume of liquid manure wastewater and run-off produced

Use this worksheet to calculate the amount of liquid manure and run-off produced.

Example

3000 head at an average weight of 750 lbs
Critical storage period = 150 days per year.
750 lb beef cattle = 5.3 gallons per day at 88.4 % moisture
25yr/24hr storm = 2.2 inches precipitation (see map)
Lot area = 4.36 acres or 189,921 sq. ft. (1 acre = 43,560 sq. ft.)

 

1. 5.3 gallons x 88.4% = 39.78 gallons manure

2. 39.78 gallons x 150 days = 5967 gallons manure/head/year

3. 5967 gallons x 3000 head = 17,901,000 gallons manure wastewater/year

4. Runoff = [(P - 0.5) ÷ 12 in./ft] x LA
Variables: RO = lot runoff, ac-ft

 

 P = Precipitation, inches
  LA = lot area, acres
RO = [(2.2 – 0.5) ÷ 12] x 4.36 ac = 0.62 ac-ft
There are 350,850 gallons in 1 ac-ft. Therefore, 0.62 ac-ft equals 217,527 gallons.
5. Add lines 3 and 4: 17,901,000 + 217,527 = 18,118,527 gallons

 

Your Facility

  • # head ____________ and average weight _______________
  • critical storage period = ________________
  • # gallons/per day ___________ and % of wet material __________
  • 25yr/24hr storm = __________inches precipitation (see map)
  • Lot area = _______ acres or ______ sq. ft. (1 acre = 43,560 sq. ft.)

 

1. _____ gallons x _____ % moisture = 39.78 gallons manure

2. _____ gallons x ______ critical storage days = ______ gallons manure/head/year

3. ____ gallons x ______head = _________ gallons manure wastewater/year

4. Runoff = [(P - 0.5) ÷ 12 in./ft] x LA

  • [(____ inches precip.- 0.5) ÷ 12 in/ft.] x _____ lot area acres = _____ ac-ft
  • There are 350,850 gallons in 1 ac-ft. Therefore = ____________ gallons runoff.

5. Total gallons of wastewater and runoff (add lines 3 and 4) = _________ gallons.