Mark Rice - Planning for Emergency Mass-Depopulation of Swine in Response to a Foreign Animal...
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1 Planning for an emergency depopulation of swine in response to a foreign animal disease outbreak • WE Morgan Morrow, RE Meyer, JT Whitley, CS Whisnant, • LF Stikeleather, CL Baird, JM Rice, BV Halbert, HS Byrne, JA Lavin, D Cornejo, DK Styles • Mississippi State University • North Carolina State University • USDA-APHIS Veterinary Services • Department of Homeland Security • Murphy Brown LLC
Mark Rice - Planning for Emergency Mass-Depopulation of Swine in Response to a Foreign Animal Disease Outbreak
1. 1 Planning for an emergency depopulation of swine in
response to a foreign animal disease outbreak WE Morgan Morrow, RE
Meyer, JT Whitley, CS Whisnant, LF Stikeleather, CL Baird, JM Rice,
BV Halbert, HS Byrne, JA Lavin, D Cornejo, DK Styles Mississippi
State University North Carolina State University USDA-APHIS
Veterinary Services Department of Homeland Security Murphy Brown
LLC
2. Outline Define the problem Propose a possible approach
Introduce some planning tools 2
3. I am not here to convince you that I have all the answers
but rather to get you to: Start thinking now about what you would
do if the situation arises Be prepared Every situation is different
3
4. What is Mass Depopulation? As defined by the AVMA: methods
by which large numbers of animals must be destroyed quickly and
efficiently with as much consideration given to the welfare of the
animals as practicable, but where the circumstances and tasks
facing those doing the depopulation are understood to be
extenuating Includes: disease outbreaks, contamination with
chemicals (eg, dioxin) or radionuclides (eg, cesium 137), and
situations severely limiting feed deliveries and animal
movement.
5. Why CO2? Readily available, low cost, nonflammable
Anesthesia due to pH Produces unconsciousness and kills over wide
range of concentrations Exposure to 60% to 90% CO2 causes
unconsciousness in 14 to 30 seconds, with unconsciousness occurring
prior to onset of signs of excitation. Conc < 30% not aversive
to pigs (Raj & Gregory 1995) AVMA- , AASV-approved for humane
killing of swine Reversible should personnel be exposed
6. Our Objectives Recognized the benefit of getting the pigs
out of the buildings Easier to manage their disposal once outside
Figure out how to do mass-depop in the field Focused on gassing
Develop alternatives for: Containment.corrals low pressure CO2
(head space vs liquid) Gas containment.bladders
7. Our Objectives (cont.) Understand CO2/O2 dynamics in the
containers. Computer simulations/CFD analyses. How to deliver CO2,
manifolds. Temperature, avoid freezing pigs (evaporators/earth
tubes). Time to 30% CO2 (non aversive).
8. Our Objectives (cont.) Time to loss of righting reflex
(LORR) unconsciousness. Time to death.cycle time is very important.
Simulate cycles to better understand effects of limiting inputs
(labor, gas, containers, pig movement). Generally to better
understand the process and develop alternatives. The devils in the
details!
9. Ideally Equipment and supplies readily available (Home
Depot/Lowes) or stockpiled ahead of time Well-documented methods
Easy to apply by field personnel Scale-able to large
numbers/throughput Efficiency benchmarked by time-motion studies As
humane as possible under the circumstances
10. 10 CO2 Mass Depopulation - What you need and how to do
it.
11. When using CO2 for euthanizing animals - size/scale does
matter CO2 is generally delivered as a pressurized liquid For low
flow rates draw off head space gas For high flow rates will require
releasing high pressure liquid when liquid CO2 is released
approximately 54% is released as a gas, the remaining (46%) forms
dry ice To meet AVMA recommendations must replace chamber volume
within 5-minutes
12. Small scale - bleed directly from CO2 pressurized cylinder
into chamber For: nursery pigs and small chambers such as hand
carts or bins
13. Intermediate scale bleed from a high pressure CO2 cylinder
to low pressure tank Suitable for small trucks or dump trailers
Liquid CO2 flow rate is low enough to avoid line and regulator
freeze up At low flow rate, CO2 gas in the low pressure tank will
approach ambient temperature Orifice is sized to control flow from
the low pressure tank to chamber
14. Low pressure CO2 tank High pressure CO2 cylinder Euthanasia
Chamber (Trailer) CO2 pressure regulator 1 1 Regulator would
maintain preset pressure in the low pressure tank between
application events. 2 Relief pressure setting should be slightly
above required low pressure CO2 tank pressure but well below the
maximum tank pressure rating. Safety pressure relief valve2 Orifice
plate Ball valve
15. What if you need to go Large Scale? dumpsters, trucks, or
larger chambers or pits
16. Turnkey vaporizer for large scale use of CO2 $$$$ -
$120,000 + trailer? 60 Kw generator - $25,000 +
17. Low-cost vaporizer system to capture and sublimate dry ice
produced during the application of liquid CO2 and also temper gas
temperature < $2,500 including heaters 3.5 kw generator
approximately $500
18. CO2 vapor collection reservoir (Ag-Bag)
19. CO2 vapor collection reservoir (Ag-Bag)
20. Assembly Guide: Mass Swine Depopulation System Utilizing
Carbon Dioxide
21. System Schematic (Details provide in subsequent
slides)
22. Vaporizer Chamber should be a gas tight vessel capable of
withstanding 500-600 degree Fahrenheit and with a pressure relief
valve installed to prevent pressure buildup. We have utilized
55-gallon metal drums as well as 250 and 500 gallon, used propane
tanks
23. Heat Enclosure designed to improve heat transfer to the
vaporizer chamber. It should be exhausted to prevent excess
backpressure on the heaters. Concrete block can be stacked without
mortar to create an enclosure around the vaporizer tank
24. The liquid CO2 connection is critical. Check with your CO2
supplier to make sure you have the correct connects available to
enable their trucks to connect to your system. A pressure drop
valve is necessary near the inlet of the tank to prevent dry ice
formation in the feed hose or truck valve. Liquid CO2 connection to
truck Needle valve used to drop the liquid CO2 pressure
25. Heat Exchanger to prevent cold CO2 gas from being
introduced into the chamber the CO2 gas temperature sho be
increased to near ambient temperature. This can be accomplished by
adding a metal heat exchanger coil inside the heat enclosure.
26. CO2 gas to heat exchanger CO2 gas by-pass valve valve
Valves can be adjusted to regulate the flow of CO2 gas through the
heat exchanger to provide the appropriate CO2 gas temperature to
the chamber. Heat Exchanger Plumbing Diagram
27. CO2 Gas Accumulation (optional) a gas collect/temporary
storage bladder will help provide a more consistent flow of gas to
the depopulation chamber. Bladders can be constructed with plastic
sheeting by taping the seams or Ag Bag silage storage bags by
folding/clamping the ends.
28. Flow Regulation To meet the AVMA requirement the
depopulation chamber volume must be filled over a 5- minute period.
A blower can be used to move the CO2 gas from the accumulation bag
to the chamber. To ensure proper flow rates, a field constructed
venturi and monometer can be assembled.
29. Venturi with common parts Two 6x4 PVC reducers with
standard PVC pipe sections.
30. Reading the differential pressure in inches of water
(H2O)
31. Flowrate of CO2 (0-60F) as function of Inches of water
differential pressure 0 1 2 3 4 5 6 7 8 100 200 300 400 500 600
InH2O Cubic feet per min. (CFM) of CO2 when at 0 -60F Inches H2O
vs. CO2 Flowrate @ 0-60F with 6x4 PVC venturi CFM of CO2 at 0F CFM
of CO2 at 60F
32. Depopulation Chamber Sized to accommodate the farm needs
and the capabilities of the vaporizer unit. Deliver CO2 to the
floor of the chamber. Since CO2 is heavier than air the lower part
of the chamber must gas tight. Earthen pits or sealed truck bodies
could be utilized as chambers.
33. The heat capacity and number of heaters will be determined
by the desired CO2 flow rate. Each cubic foot of chamber capacity
will require about 600 btu/hr heat capacity. Heat input can be
supplied from several sources but kerosene, torpedo style heaters
are readily available and provide more consistent output than
propane fueled heaters. Kerosene heaters positioned into openings
in block walls
34. Planning for Mass Depopulation 1) Decide on chamber size,
i.e. trucks, corral, pit. 2) Determine volume of chamber (length x
width x depth) 3) Determine required flow rate (volume/5 minutes)
4) Size components according to required flow rate. To prevent dry
ice accumulation and raise the temperature of the CO2 gas to near
ambient temperature, for each cubic foot of chamber capacity will
require approximately 600 btu/hour of heat capacity
35. Planning for Mass Depopulation Example: 1) Decide to use a
pit that is 10 wide, 40 long, and 3 deep 2) Determine the volume:
10 x 40 x 3 = 1,200 cu. ft. 3) Determine required CO2 gas flow
rate: To fill the chamber volume in 5 minutes: 1,200 cu.ft./5 min.
= 240 cu. ft./min. 4) Heat requirement: 1,200 cubic feet chamber
capacity x 600 btu/hr capacity = 720,000 btu/hour (If 125,000
btu/hr heaters are available, it would require 6 of them.
36. Jobs, Innovation, Growth, Stability www.ies.ncsu.edu
Planning Tools for Mass Depop Events David Cornejo Ph.D. Candidate
in Operations Research
37. Goals Strategic(Before) Develop basic estimates of resource
requirements before disaster. Tactical(During) Assist in
identifying resource savings/need during event. Delivery via Web
application 43
38. System Overview 4 Distinct Stages Moving pigs from house to
loading chute Loading pigs onto available trucks Preparing trucks
and gas application Disposal of carcasses METRIC: Time to complete
process. 44
39. Moving Pigs from house to truck Influenced by following
user inputs Pigs: Number, Weight class Houses: Number, Size,
Loading chute length Workers: Number available Variables affect
Travel Time of run. 45
40. Load Truck Pigs Loaded onto truck Capacity of trucks from
pig weight class Details One or more loading chutes available 46
Class Name Space Requirement(sq. ft./pig) Nursing (