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TOWARD A SCIENCE-BASED AGRICULTURAL ODOUR PROGRAM FOR ONTARIO: A COMPARISON OF THE MDS AND OFFSET ODOUR SETBACK SYSTEMS

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org

Citation:  Pp. 336-345 in Air Pollution from Agricultural Operations III, Proceedings of the 12-15 October 2003 Conference (Research Triangle Park, North Carolina USA), Publication Date 12 October 2003.  701P1403.(doi:10.13031/2013.15527)
Authors:   W. R. MacMillan and H. W. Fraser
Keywords:   Agricultural odours, Barn sitting, Livestock barns, Manure odours, Separation distances, Separation formula

Ontario has a long history of using prescribed separation distances to minimize nuisance disturbances related to odours from livestock facilities. The Minimum Distance Separation (MDS) system is an experiential, empirically based system that has been used to effectively minimized livestock related odour complaints for over 25 years. Odour complaints are rare where livestock facilities are properly managed and sited using MDS. In spite of its effectiveness, MDS is coming under increasing criticism from both farmers and the public as follows:

--It is subjective and not based on clear, documented scientific data

--It is cumbersome and difficult to use and understand

--The MDS expansion factor is confusing and appears to allow uncontrolled livestock operation

--MDS is outdated and unable to predict adequate separation distances for the newer, larger barns

--MDS unable to quantitatively account for odour control technologies, such as biofilters and manure treatment systems

The livestock unit (LU) based MDS system is unable to predict separation distances for independent manure storage processing facilities and other agricultural odour sources where no animals are present.

These criticisms have lead Ontario to initiate a program to reevaluate the MDS system. A first step toward modifying the MDS system is to develop analytical comparisons with some of the more science-based odour emissions models to allow calibration of the MDS curves. This paper compares separation distance predicted by MDS to those predicted by Minnesota’s Odour From Feedlot Setback Estimation Tool (OFFSET). The OFFSET model was developed using real odour emissions data and dispersion modeling techniques. To allow reasonable comparisons the OFFSET model was calibrated to Ontario’s climatic conditions and calculations were made using both systems under similar construction and management regimes for swine, poultry, dairy and beef cattle facilities. Results from the two separation distance models were compared using 93% and 96% annoyance-free criteria from the OFFSET model to emulate the MDS nearest single neighbor and high occupancy/sensitive land use criteria, respectively. Results of the comparison show that MDS separation distances compare favorably to those from the more science-based OFFSET model. Where under-barn manure storage was used, only large (> 10,000 animals) SEW weaner barns were shown to be sited too close to neighboring land uses by the MDS methodology. Where, manure was stored in uncovered, exterior storage systems only finishing and farrow-to-finish hog operations consistently meet the selected OFFSET annoyance-free criteria when sited using the MDS system. It was concluded that work is needed to verify and modify the MDS system to increase public confidence and improve the utility of the MDS system. The MDS expansion factor needs to be verified and a mechanism to account for odour control technologies should be developed. Future research should be collaborative to improve research efficiencies and improve public acceptance of the system. (Download PDF)    (Export to EndNotes)