Deciding how to dispose of large numbers of Animal Carcasses in an Environmentally-Friendly Manner---European Commission for the Control of Foot-and-Mouth Disease

http://www.fao.org/waicent/FaoInfo/Agricult/AGA/AGAH/EUFMD/reports/rg1999ma/
app23.htm
© European Commission for the Control of Foot-and-Mouth Disease

Appendix 23 - Deciding how to dispose of large numbers of Animal Carcasses in an Environmentally-Friendly Manner
 

John Ryan, EUFMD Secretariat
 

Introduction
National Veterinary Services face increasingly difficult tasks and a
greater workload than ever before as the volumes and complexity of world
trade in animals and animal products increases. Compounding these
difficulties, the National Veterinary Services are increasingly having to
serve the interests of not only the agricultural industry but consumers,
animal welfarists and environmentalists also.

There has never been an objection within the veterinary profession to
serving any of these constituencies. However, as public and scientific
awareness of welfare and environmental issues rises, more constraints than
ever before are placed on the actions and interventions of the national
veterinary services. No longer can an intervention such as emergency
slaughter be justified on epidemiological and economic grounds to the
agricultural industry, it must also be justified on welfare and
environmental grounds to an increasingly sceptical general public too.

Recent massive epidemics of contagious diseases such as BSE in the UK,
Classical Swine Fever in the Netherlands, Avian Influenza in Hong Kong and
FMD in Taiwan and the realisation that National Veterinary Services are
working more and more under the spotlight of media and interest group
attention has provoked concern among Chief Veterinary Officers world-wide.

Halting the spread of highly contagious animal diseases is always a
difficult task and the available tools are limited. "Stamping-out" with its
associated measures such as movement controls, disinfection routines and
destruction of infected and potentially infected carcasses is a highly
effective tool for controlling and eradicating contagious animal diseases.
However, it does not appeal to the general public nor the animal welfare
activists and often not even to the agricultural industry itself.
Furthermore, when stamping out is contemplated on a large scale it poses a
threat to the environment also.

These concerns were voiced by the Chief Veterinary Officers of member
countries at the 33rd General Session of EUFMD in Rome on 4-5th April 1999,
where they formally requested the Research Group to examine the problem of
the environmental impact of disposing of large numbers of animal carcasses
in an environmentally friendly manner. This paper is intended to introduce
the topic and hopefully stimulate some further interest and research.

 

The Options
The options for disposal of animal carcasses on a routine basis e.g.
casualty animals, pets etc. are generally prescribed by law in most
countries. Directive 90/667/EC on animal disposal confirms the

acceptable disposal routes as a treatment or processing plant; or burning;
or burial.

For small scale disposal problems these regulations are generally
acceptable, but it is not always possible or safe for the environment for
these methods to be used on a large scale such as large scale animal
disease epizootics like those mentioned in the introduction. While many
countries have guidelines on what to do with carcasses slaughtered in
contagious disease emergencies, it is not clear if there are any scientific
studies demonstrating the safety of these protocols for the environment.

The only literature that comes close to approaching this problem is that of
agricultural engineering, where the engineers have contemplated the
environmental safety of disposing of the regular and often large numbers of
mortalities associated with intensive poultry and pig production. However,
this literature generally prescribes measures that appear to be
insufficient in dealing with highly contagious animal disease and would
have huge difficulties in scaling up from 5% of a herd capacity to full
herd capacity. (I have listed some of these methods in the Other Potential
Options section below)

This leaves us with the three generally prescribed methods of carcass
disposal, rendering, burning and burying, and the advantages and
disadvantages of these methods are discussed below. In order to stimulate
discussion and some lateral thinking, I have also listed some non-standard
solutions to this problem in the section titled Other Potential Options below.

 

Rendering
National and European Union regulations tightly control and regulate the
rendering process particularly since the BSE crisis. National Environmental
Agencies will ensure that these plants operate in a manner that poses
negligible threats to the environment. A critical area for
environmentalists and veterinarians is the method for treating waste water
and effluent from these plants.

 

Advantages
Efficient elimination of virus.
Recovery of Meat and Bone Meal (may help offset costs and is less wasteful).
Negligible risk to the environment if the plant complies with the relevant
licensing laws and environmental agency provisions.
More acceptable to the general public.
Disadvantages
Limited short term capacity in any given area for dealing with outbreaks.
Possibly limited long term capacity in all of Europe as the economics of
the rendering business become unfavourable.
Requires transport of infected material often over long distances and
through clean areas.
May require cold-storage of carcasses on site for prolonged periods to deal
with large volumes.
 

Incineration
There are two methods of incinerating carcasses, on-farm funeral pyres and
specially built or adapted commercial incinerators. Specially built
incinerators may offer the potential to use the calorific value of the
incinerated carcasses and are therefore less wasteful.

 

Funeral Pyres
There are many guidelines available on how to practically construct
effective Funeral Pyres, the environmental impact of these pyres has rarely
been studied.

 

Advantages
Effectively eliminates virus.
Can be carried out on most farms even on those farms where burial is not
feasible.
No transport of infected material off-farm.
No long term significant environmental damage is believed to result.
Disadvantages
Smoke is a significant short term pollutant and may be totally unacceptable
if human dwellings are downwind or in certain weather conditions.
CO, VOC's, NOX, dioxins, SO2, HCL and heavy metals are the other
significant airborne pollutants that regrettably are difficult to monitor
from an open pyre.
These pollutants pose particular difficulties in the context of large
numbers of pyres located close together as in a cluster of outbreaks.
Negative emotional reaction is to be expected from the general public and
it may fuel significant animal welfare resistance to the slaughter policy.
Odours from the pyre are a significant public nuisance
Pyres can be very long with 3 feet required per adult cow.
Ground water may be affected by the hydrocarbons used as initiators and
accelerators.
Ashes must still be disposed of in a suitable licensed landfill site.
 

Incinerators
Construction and operation of incinerators must meet strict environmental
regulations as laid down by the national environmental agency.

 

Advantages
Effectively eliminates virus.
Risk assessments have demonstrated that the risks to the environment are
negligible if licensed and operated according to the guidelines of the
relevant Environmental Agency.
Carcasses, like meat and bone meal, are a good grade fuel and it is
environmentally preferable to recover the energy from the carcass whenever
possible.
Easy to monitor compliance with emission levels.
Air scrubbing or filtering processes can be added if necessary.
No odour should be detectable at the boundary of the premises.
 

Disadvantages
Limited short term capacity in any given area.
Requires transport of infected material often over long distances and
through clean areas.
May require cold-storage of carcasses on site for prolonged periods to meet
large volumes.
CO, VOC's, NOX, dioxins, particulates, SO2, HCL and heavy metals are
significant pollutants that may be released by incineration.
 

Burial
Regulations on the burial of carcasses can also be widely found in national
legislation, and while these ensure that the risk of FMD virus resurfacing
from the burial pits is negligible, no scientific proof of the safety of
this measure for the environment was found. Most legislation will describe
in detail the selection of suitable sites based on soil type and depth to
the watertable. Some countries have already zoned their country in advance
to identify areas that are suitable and not suitable for burial,
particularly in relation to groundwater used for human consumption. Most
regulations specify the following or close variants of it:

The trench (the most suitable shape for filling and burial) must be deep
enough to allow sufficient topsoil coverage to prevent carnivorous animals
or vermin access to the carcasses.
Suitable soil type and depth to prevent contamination of groundwater is
usually pre-determined from zoned groundwater maps.
Usually on level ground, slopes are not suitable.
At least 250-300m from a well, 10m from a field drain and 30m from a spring
or watercourse
Minimum of 1m subsoil below the pit, base of pit free of standing water,
and 1m soil cover over carcasses. Carcasses at least 1m above watertable
(carcasses take approx. 1m). As carcasses take up 1m depth, 3m is the
minimum depth required but usually 4m depth is used.
A Quicklime lining and covering on the carcasses is used to inactivate
virus in the leechate.
Beware of private water sources using local groundwater that may not be
included in geological maps of ground water uses.
Protocols for fencing off the site and for when animals can subsequently
have access to the site.
Regulatory authorities when examining the burial site subsequently would
look for indicators such as faecal coliforms, faecal streptococcus,
chloride, and various nitrogenous breakdown products in the groundwater at
various depths and distances from the burial site.

 

On Farm
Advantages
Negligible risk of virus resurfacing.
No risky transport required.
Very inexpensive.
Bacteria (and possibly viruses) seem not to move very far in soil. Faecal
coliforms and faecal streptococcus were found to be very low when measured
around dead bird disposal pits (Ritter and Chirnside, 1995).
Possibly more acceptable and discrete than burning to the general public.
Disadvantages
Availability of suitable sites may be limited or non-existent in certain
geological areas.
No proof that large scale burials do not have long term detrimental effects
on the environment.
Acceptable carcass load for any given area or volume of groundwater
catchment has not been determined.
Greatest impact may be caused by toxic breakdown products such as ammonia,
nitrites and chloride. There is evidence that this occurs around dead bird
disposal pits (Ritter and Chirnside, 1995), which it must be remembered are
on a much smaller scale than would be the case in the event of a large
epidemic of FMD.
 

Landfills
Usually stringently controlled by the licensing authority and will have
very large plastic lined pits to prevent the escape of leechate to the
ground water. The leechate is subsequently drained off and treated
(chemically, biologically or by heat).

 

Advantages
Properly licensed and operated sites pose little risk to the environment
The risk of virus disseminating or resurfacing can be negated by veterinary
specific protocols.
High capacity with the necessary machinery usually readily available or
already in place.
Disadvantages
Licensing is difficult to obtain.
Pits used for carcass disposal must be closed soon after filling and thus
the capacity of the pits designed for domestic waste can be greatly reduced
Availability is limited and owners and planning authorities may not want to
sacrifice precious available landfill sites
Transport to the sites is dangerous for the dissemination of virus
Expensive
Vermin and birds may present problems while filling
 

Other Potential Options
These are presented as extreme examples of possibilities for disposal of
carcasses in general. Their environmental impact and suitability for FMD
infected carcasses is not known but these or other novel ideas may lead us
new approaches to this problem. These are also ideas that may be worth
exploring for other diseases not as contagious as FMD.

On-Farm Processing
Composting
Fermentation
Sterilisation
Dumping at Sea?
Deep Mines?

 

The Decision
The following sections outline the factors one needs to take into
consideration in deciding how to dispose of large numbers of carcasses.

 

Don't ever get into a position to need it!
Preventing this problem from ever arising is by far the best strategy.
National Veterinary Services should concentrate their efforts on preventing
the introduction of FMD and having sufficient awareness and an effective
contingency plan to ensure that the disease is rapidly stamped out before
the number of carcasses to be disposed of reaches levels where the
environmental impact is significant. A CVO will never have to justify
slaughtering only one herd in controlling an outbreak to animal welfare
groups or environmentalists!

This is advice that is easily given, but in the real world it is extremely
difficult to implement and cases will arise where there will be large
numbers of animal carcasses to be disposed of and some framework should
guide the decision on how they will be disposed of. As with every other
aspect of dealing with FMD outbreaks, advance preparation is critical for
timely and successful decision making and disposal of the carcasses in an
environmentally friendly manner. Detailed plans and advance contracts for
the equipment, personnel and services required for disposal of carcasses
should be an integral part of any FMD Contingency Plan.

 

Advance Preparation
Groundwater maps and consultation with a specialist from the national
environmental agency will identify areas of the country that are suitable
for burial and funeral pyres.

Other essential maps and data that need to be collected in advance of an
outbreak and updated regularly are the location of Rendering plants,
Slaughter Houses, Incinerators licensed and equipped to handle animal
carcasses and Landfill sites that are licensed and equipped to handle
animal carcasses. If no incinerators or land-fill sites are licensed to
accept animal carcasses or if they are of limited capacity or of limited
geographical distribution, then it may be useful to encourage existing
facilities to upgrade and become licensed for this purpose.

Other useful information to have would be the locations and dates of
previous large scale burials and maps locating human settlements.
Meteorological data on wind speeds and directions will of course also be
necessary for siting funeral pyres, but as it is necessary for modelling
airborne spread of virus from infected farms, it should be available by
prior arrangement already.

Advance arrangements for the supply of necessary equipment or services are
highly recommended. For example, sealed trucks with functioning and
disinfectable waste tanks for the transport of carcasses to landfills,
rendering plants or incinerators. Excavators, quick lime, fencing
contractors will be required for burials.

For funeral pyres the list of requirements is significant and may not be
readily available in crisis times: Sleepers; Straw; Kindlewood; IsoKal or
tyres; Coal; Plastic bags; fork lifts/trucks/tractors with bucket loaders
for moving fire ingredients and carcasses; diesel for singeing and
initiating the fire; lamps to keep vermin away from stored carcasses and to
allow night working; hand forks; rakes; eyegoggles; heavy gloves; and
firetenders for two nights are all listed as requirements for an effective
pyre.

 

Deciding by Setting Priorities
At all times the number one priority is ensuring the complete destruction
of all FMD virus and ensuring that in no way will any process or action
that takes place during the disposal of the carcasses result in further
spread of the virus.

Due to the lack of data on the long term environmental damage from the
disposal of carcasses by the most popular on-farm options, the next
priority should be to limit the environmental damage from the disposal
activities. The simplest method of doing this for a particularly large
environmental load (e.g. in a high density intensive production area) is to
share the load across as many disposal routes as possible. For example,
exhausting local rendering capacity then exhausting local incinerators
capacity, then a combination of burying where feasible and creating funeral
pyres for the balance of the load may be a good strategy for certain areas.
For other areas where the farms are remote from human settlements, funeral
pyres may be the best method. In areas with a deep watertable and a large
catchment area where the ground water is not used for human consumption
then burial may be the best option.

The exact number of carcasses disposed of by each method should be
determined on the spot by examining the local possibilities and
constraints. In very constrained circumstances methods to regulate the flow
of carcasses for disposal should be considered (e.g. cold storage until
there is rendering or incineration capacity). It may also be preferable to
store carcasses on the farm of origin under supervision until capacity is
available for their safe disposal.

The other very important factors to consider are time and cost. The need
for rapid decision-making and disposal makes this decision very difficult
on the ground as the decision-maker will never know what his future
disposal load will be.

 

Theory of Constraints
This problem is a classic Theory of Constraints problem. The solver
function in Microsoft Excel allows the creation of a spreadsheet which can
aid the decision on how to distribute the carcasses over the different
disposal methods available in the location with given capacity constraints
for burying, local incineration or rendering. It can also be used to help
minimise the costs of the disposal operation.

 

Conclusions
Give the environment a break....ensure that the decision on how to dispose
of large numbers of animal carcasses has never to be taken, by preventing
the introduction of FMD and having a ruthlessly efficient contingency plan
in place to eradicate the disease in a short period of time with the
minimum number of animals destroyed.

Prepare as much information in advance on the options for disposal, in case
it is needed.

Slaughter the animals that need to slaughtered first and then worry about
disposal. It may be beneficial for there to be a division of
responsibilities in this matter so that the person deciding what farms to
slaughter is not influenced unduly by the disposal problem. Another expert
may have the sole responsibility for disposal of the carcasses
subsequently. Holding slaughtered animals on-farm for a long period may not
be particularly risky for the dissemination of the virus while the decision
is made on finding a safe method for their disposal.

Make the decision on the spot on how to dispose of the carcasses based on
local factors and use a variety of methods to reduce the environmental "load".

Prioritise the least environmentally damaging options such as rendering,
incineration and land filling in licensed and approved facilities. When
transporting the carcasses ensure that they are in totally sealed and
disinfected trucks and that all other measures are taken to prevent
distribution of the virus.

If feasible, cold-storage of slaughtered carcasses can be a means to
continue using environmentally-friendly methods when their daily capacities
are exceeded.

Funeral pyres and local burial of carcasses should be used whenever the
capacity of environmentally sound techniques are exhausted and when a
suitable local site can be found.

An on-farm disposal method should always be used if the absolute security
of transport to a disposal plant cannot be guaranteed.

Always follow the prescribed guidelines on how to select a site for burial
and funeral pyres. Always follow the prescribed procedure for burning and
burial.

Document the location, amount of carcasses and disposal procedure used in
each site for burial. Fence off the site for the prescribed period and
monitor the safety of nearby groundwater subsequently.

 

The Future
There are many unknown factors in trying to approach this problem. Limited
knowledge of the real or imaginary risks from current disposal methods; of
the likely reactions of the different interest groups; of the usefulness
and safety of new techniques etc. With so many unknowns, it is difficult to
see where the attention of researchers should be directed in order to find
the solution to this problem.

For the moment, avenues should be pursued to make existing methods more
environmentally friendly. For example:

Licensing rendering and incineration plants;
Mapping the country for the availability of safe burial sites;
Improving on-farm incineration to reduce pollutants (air curtain
accelerators);
Investigating the use of land-fill technologies on farm (esp. for very
large units);
Investigating the possibility of designing mobile rendering or incineration
units;
Investigating the dangers of storage of carcasses on farm until suitable
disposals methods are available.
The solution is never going to be a simple one but with awareness of the
options available; a consideration of the real concerns of the various
interest groups and the use of combinations of methods to reduce the
environmental "load", an optimal solution may be found for each unique
circumstance.

 

References
Crane, N (1997) "Animal Disposal and the Environment" State Veterinary
Journal Vol. 7, No. 3 October 1997, MAFF(UK).

FAO (1990) "FAO seminar on emergency action against FMD (Mediterranean)"
FAO reports.

Ritter, W.F. & Chirnside (1995) "Impact of Dead Bird Disposal Pits on
Ground-Water Quality on the Delmarva Peninsula" Bioresource Technology 53
105-111.

Moutou, F.(1995) "Destruction des cadavres. La démarche francaise" personal
communication.

AUSVETPLAN (1996) "Disposal Procedures" Agriculture and Resource Management
Council of Australia and New Zealand.

The Environment Agency (UK), Technical Guidance Notes: IPC S2 5.01
Amplification Note on Animal Remains Incineration (1997) and IPC S21.05
Amplification Note on Combustion of Meat & Bone Meal (1998) from
http://www.environment-agency.gov.uk/epns/ipchome.html.

Richardson, H., UK Environment Agency, personal communications.

Morton, T., veterinary advisor to MAFF (UK), personal communications.