Livestock Odor Setback Model – Purdue University

Disclaimer

Purdue University does not accept any responsibility for any errors in, or for any errors that may result from using the setback guideline. We expressly disclaim any responsibility for any damage arising from the application or reliance on the recommendations and information contained herein.

Purdue Setback Model – June 2015 (NOTE: This may be updated periodically).

Purdue Setback Model Instruction Manual

Odor nuisance is a concern of livestock producers and their neighbors. The use of atmospheric air to dilute odors from livestock production facilities through appropriate setback distances is a cost-effective odor control strategy. However, the determination of such setbacks is difficult and complex.

A simple-to-use, site-specific odor setback model was developed by Purdue University. This guideline considers facility size, orientation and shape, wind frequency, land use, topography, building design and management, manure handling characteristics, and odor abatement. Odor emission factors were based on actual measurements and literature reported odor emission measurements at commercial livestock farms and manure production rates. Atmospheric dispersion models and downwind odor measurements have been utilized to enhance and validate the setback guideline. The Purdue Setback Model (PSM) combines features of Austrian and British setback guidelines (Schauberger and Piringer, 1997; Williams and Thompson, 1985) and incorporates new features developed through our research. The PSM is as follows:

Setback distance in feet = 20 F L T V (A_EE+A_SS)^0.5

where:
         F = wind frequency factor
               L = land use factor
               T = topography factor
         V = orientation and shape factor
         E = building odor emission, N x P x B, OU/s
               N = number of animals or birds
               P = odor emission factor, OU/s-hd
               B = building design and management factor, M-D
                     M = manure removal frequency
                        D = manure dilution (swine), drying (poultry) or residue (dairy) factor
         S = odor emission from outdoor storage, C x G, OU/s
               C = odor emission factor for outside liquid manure storage, 50 OU/s-AU
                     G = animal unit, AU=1100 lb of animal weight
         A_E = odor abatement factor for buildings
         A_S = odor abatement factor for outside liquid manure storage

References

Schauberger, G. and M. Piringer. 1997. Guideline to assess the protection distance to avoid annoyance by odour sensation caused by livestock husbandry. Proc. Fifth International Livestock Environment Symposium. May 29-31, pp. 170-178.

Williams, M.L. and N. Thompson. 1985. The effects of weather on odour dispersion from livestock buildings and from fields. In: Odor Prevention and Control or Organic Sludge and Livestock Farming. Ed: V.C. Nielsen, J.H. Voorburg, and P.L'Hermite. Elsevier, New York, pp. 227-233.