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Emergency Livestock Disposal Home
Project Executive Summary
Project in Detail
Draft Guidelines for Emergency Cattle
Mortality Composting
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PRELIMINARY RESULTS
Air Quality
Odor Threshold Data
The chart above shows mean (N=4) threshold odor values for air samples collected from the surface of cattle carcass composting test units in trial # 5. Samples were collected on the day of construction (Nov. 11, 2003), and 7 and 21 days later.
To provide a basis for judging the intensity of the odor emanating from the carcass composting units (and recognizing that the cover materials themselves....particularly the silage.... contribute to this odor), data for the composting test units (plain bars) are plotted next to data for the cover material stockpiles (cross-hatched bars).
With the exception of samples taken from the silage test units on the date of construction, all other values are less than 1500, and many are less than 1,000. As shown by the following table of typical threshold odor values, these numbers are considered to be quite low. Furthermore, it must be emphasized that the data charted above are for samples taken directly from the surface of the composting test units. At downwind locations, little if any odor has been detected.
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Odor Sample Collection Location |
Typical Odor Threshold |
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Surface of lake in Iowa |
200-300 |
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Liquid surface of properly operated secondary cell of a manure lagoon (State of Colorado allowable odor standard) |
1,000 - 2,000 |
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Liquid surface of properly operated primary cell of a manure lagoon (State of Colorado allowable odor standard) |
4,000 - 6,000 |
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Surface of untreated manure slurry basin |
10,000 |
Typical odor values courtesy of Dr. Dwaine Bundy, olfactometery laboratory, Department of Agricultural & Biosystems Engineering, Iowa State University.
Odor data in the chart also show that 18-inches of cover material (minimum) used in the test units does a good job of retaining odor components contributed by the cattle carcasses. In many cases there is very little difference between the threshold odor values for the stockpiled cover material, and the values for the composting test units.
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In Brief
1. Threshold odor data indicate that odor in the immediate vicinity of the composting test units is very low.
2. In many cases, odor from composting test units cannot be distinguished from the odors emanating from stockpiles of the cover material.
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