North and West Queensland weather event, February 2019— Carcass disposal

The information provided in this fact sheet has been developed with specific consideration to the situation arising from the 2019 floods in North and West Queensland. Special thanks to the Department of Environment and Science for technical expertise and New South Wales Department of Primary Industries for their fact sheet Animal carcass disposal.

Overview

The unique situation of livestock mortalities in the 2019 northern and western Queensland floods presents particular challenges for carcass disposal related to:

  • dispersed distribution of carcasses across flooded land
  • extended time since death resulting in significant carcass decay
  • difficulties in carcass handling due to advanced state of decay
  • waterlogging of black soils delaying movement of vehicles and machinery
  • availability of excavation and transport machinery in the affected locations
  • odour and disease concerns due to proximity to urban and residential areas
  • potential water resource contamination, e.g., due to proximity of carcasses to dams and drainage lines.

Carcass disposal in the current situation needs to take into account the need for long term, low-maintenance disposal options, considering the physical and practical constraints of the locations, sensitivities (proximity to urban, residential locations, water bodies) and available resources.

Producers can apply for $5000 Australian Government carcass disposal grants to help with disposal costs through their local council.

Importance of effective carcass disposal

Improper carcass disposal can have impacts on the environment as well as human and animal health. Poor carcass disposal can result in contamination of soil, groundwater and waterways. Access to poorly disposed carcasses can also allow for disease spread to other stock through scavengers, mosquitoes and vermin.

Responsible disposal is important to ensure the safety of the community, other stock, the environment and to minimise the risk of disease spread.

Disposal options

There are many disposal methods including burial, burning and composting. However given the current circumstances, burial is the most practical option.

Safe handling of carcasses

Carcasses should be handled as little as possible. Where possible use a machine (excavator or backhoe) to handle the carcass. Appropriate personal protective equipment (PPE) should be worn when handling a carcass, especially if large amounts of dust, fumes or body fluids are produced. Any cuts or broken skin should be cleaned and covered with a waterproof dressing prior to commencing disposal activities. Hand washing with soap and clean water should always be performed after contact with animals and after removing PPE.

PPE should include:

  • gloves
  • leather or rubber boots
  • clothes that cover exposed skin and
  • eye protection.

Take reasonable efforts to protect yourself from the inhalation of dust or other aerosols where Q fever infection may be a risk. Wearing a P2 mask (particulate respirator) should be considered and assessed on a case by case basis, e.g. when performing any procedures that create aerosols such as using a high-pressure cleaner to decontaminate equipment or if the environment is dry and windy, and will depend whether or not you are immune to or vaccinated for Q fever. Further information on Q fever can be found in the Queensland Health fact sheet.

Particular attention should be paid to avoid contact with any body fluids from the dead animal. If you feel unwell after handling a carcass contact your general practitioner or call the 13HEALTH information line (13 43 25 84).

Carcass disposal considerations

Where appropriate the most suitable strategy for carcass disposal is to construct small, separate burial pits to accommodate up to 10–15 carcasses each.

Where significant decay has already occurred, e.g. majority of body fluids (leachate) has drained and dispersed, discretion can be exercised in the quantity of carcass remains that are disposed of in each pit.

For small numbers of carcasses requiring onsite disposal, no special planning needs are necessary where the local site conditions are suitable as outlined in this guide.

Where larger disposal pits are required (for higher numbers of carcasses), the site should be subject to specific assessment in terms of the key considerations and likely long term risks. The Department of Environment and Science (DES) can provide assistance with determination of individual site suitability. Contact the DES Pollution Hotline on 1300 130 372.

Use of lime on decomposing carcasses

The addition of lime to burial pits is not recommended. Lime has been shown to slow down the naturally occurring decomposition process.

For above ground exposed carcasses and carcass fluids, where there is an immediate need to discourage insects and flies spreading infection and to mitigate odours, lime can be applied as a surface covering. It can be used to absorb liquid and reduce the speed of decomposition.

As a surface covering, limited amounts of lime are not considered to be environmentally significant. Caution needs to be taken when applying lime. Follow the manufacturer’s guidelines around the use of PPE, particularly to prevent the inhalation of lime dust.

Disposal pit site selection and construction

The general guidelines on the disposal of carcasses need to be applied within the context of local conditions, particularly in regards to the soils types being suitable to contain liquid leachate and having an adequate separation between the disposal pit base and underlying groundwater that may be used as a resource.

Taking into account the particular situation, the following guidelines for disposal pit site selection and construction are recommended:

  • A maximum of 10–15 carcasses per disposal pit to minimise:
    • local generation of body fluids
    • potential for fluid movement and odour releases.
  • Where multiple pits are necessary, spacing between pits should be a minimum of 25 metres for reasons of safety and to provide adequate soil to enable sufficient breakdown of body fluids.
  • The use of absorbent material in the bottom of the pit (where practical), e.g. hay and/or woodchips, to slow down release of body fluids and encourage biodegradation.
    Note: approximately 160 litres of body fluids can be expected from a fresh adult bovine carcass.
  • Construct pit and final cover as per the following burial pit construction guidelines.

Particular location characteristics

All flooded locations are by their nature low-lying and silty-clayey soils which implies reasonable soils for containment of leachate in construction pits.  This can be assessed locally by digging test pits and local information on the depth to groundwater may be available from landholders from knowledge about resource uses such as bores and windmills. However, characteristics of unusual sites should be assessed on a case-by-case basis.

For detailed information on some specific affected locations, see Particular characteristics of affected locations below.

Site assessment criteria

Criteria

Environmental factors to be assessed

Notes

1. Proximity to drinking water supply

The site will not be within 300 metres of a borehole used for drinking water.

Burial sites consisting of multiple pits of 10-15 carcasses each, in close proximity to each other are to be at least 300 metres from bores.

Not applicable to:

  • single carcass burial sites
  • single pit burial site containing 10–15 carcasses.

2. Soil characteristics

The site will be located on soil of low permeability and good stability.

All flooded locations are by their nature low-lying and silty-clayey soils which implies reasonable soils for containment in construction pits. However, characteristics of unusual sites should be assessed on a case-by-case basis.

3. Groundwater depth

Groundwater depth at the site will be at least 5 metres from the bottom of pit. i.e. minimum 5 m deep pit + 5 m buffer = 10 m surface to groundwater level.

Water tables in the affected area range from 15–300 m deep

4. Proximity to surface water

The site will be more than 100 metres from any watercourse.

 

5. Site accessibility

The site will be 250 metres from underground and above ground infrastructure (such as a powerline, telephone line, gas line, water pipes, sewerage).

 

6. Site terrain

The site will be on elevated land but with a slope of less than 6% (3.5°) (preferably less than 2% (1.15°)).

 

7. Proximity to human habitation

The site will be more than 200 metres from:

  • a town
  • any dwelling.
 

8. Proximity to protected areas

The site will not be within 250 metres of:

  • a World Heritage Area.
  • a national park or conservation area or indigenous cultural sites (including midden sites).
 

Burial pit construction guidelines

The preferred equipment for constructing of burial pits is an excavator. Pit construction should only be undertaken by persons trained and licensed to operate the required machinery. At no time during or after the construction of the pit should people enter the pit.

The preferred method of digging a pit is to construct a deep, narrow, vertically sided pit (trench burial). The pit must be deep enough to allow the carcasses to be covered with at least two metres of soil. The cover soil can be slightly mounded after backfilling.

Suggested dimensions for constructing on-site burial pits are four to five metres in depth which results in three metres of carcass depth and the two required metres of soil cover (Figure 1). The pit should be no greater than three metres wide which helps create an even spread of carcasses in the pit. The length of the burial pit will be determined by the number of carcasses requiring disposal.

For more information on the construction of burial pits and how to work out the size pit required for your situation, please refer to the AUSVETPLAN Operational Manual for disposal procedures.

If land in the area that the pit is to be constructed is too unstable or there are work and safety concerns, a pit with battered (sloped) sides may be constructed (Figure 2).

Safe use of plant and equipment

Prior to commencing carcass disposal it is important to ensure you use the most appropriate machinery for the job and ensure operators know how to use and maintain machinery correctly.  Contact with overhead powerlines and underground cabling pose extreme risk in these situations. Ensure operators work outside the 3 metre mandatory exclusion zone for energised lines. Ground conditions will impact the stability of machinery, assess this and modify work accordingly. For more workplace health and safety information see the Worksafe website.

Particular characteristics of affected locations

The general guidelines on the disposal of carcasses need to be applied within the context of local conditions, particularly in regards to the soils types being suitable to contain liquid leachate and having an adequate separation between the disposal pit base and underlying groundwater that may be used as a resource.

Particular location characteristics

All flooded locations are by their nature low-lying and silty-clayey soils which implies reasonable soils for containment of leachate in construction pits.  This can be assessed locally by digging test pits and local information on the depth to groundwater may be available from landholders from knowledge about resource uses such as bores and windmills. However, characteristics of unusual sites should be assessed on a case-by-case basis.

Cloncurry Shire

Around the township of Cloncurry existing borehole soil stratigraphy and water table data suggest that the aquifers in use are similar in nature, as follows:

  • Depth to aquifer generally deep ranging from about 15–40 metres
  • Aquifer confined or semi confined with static water levels rising under hydrostatic pressure to about 10–15 metres below ground
  • The aquifer being in porous strata including granite, dolerite and limestone overlain by various impervious units of rock, clays and silty soils.

Overall surface soils and strata appear suitable for small disposal pits with no risk to groundwater.

McKinlay Shire

Around the township of Julia Creek there are few bores, probably due to the depth of the water table, which is about 300 metres. Existing borehole soil stratigraphy and water table data suggest the aquifers in use are the same strata, or similar in nature, as follows:

  • Thick layers of variable clayey surface soils to about 25 metres.
  • Depth to useful aquifer generally deep at about 300 metres. Upper minor aquifer at about 10 metres in yellow clay noted as salty and probably unconfined and unusable for supply in flow and quality. Mid-level poor production aquifer at about 120 metres in sandstone unit.
  • Aquifer confined or semi–confined with static water levels probably rising under hydrostatic pressure but no static water levels recorded. Temperature of water of 52°C and moderate salt content indicates a confined, artesian source for main water supply.
  • The aquifer being in porous strata including sandstone overlain by various impervious units of rock, shale and clays.

Overall surface soils and strata appear suitable for small disposal pits with no risk to groundwater.

Flinders Shire

Around the township of Hughenden there are bores that tap both a deeper artesian aquifer and shallower bores in an unconfined aquifer in sandy alluvium. Existing borehole soil stratigraphy and water table data suggests the aquifers in use are similar in nature, as follows:

  • Variable surface layers of clay and shales to about 18–20 metres. More sandy lenses closer to the river.
  • Unconfined aquifer at 7–12 metres in sandy strata in some places closer to the river in alluvium mostly north of the river. Aquifer may be in use.
  • Deeper aquifer in use at 175–183 metres. Static water level at 84 metres below ground indicating artesian pressure from a confined aquifer.

Caution needs to be exercised for disposal close to larger water courses due to the presence of sandy porous layers from buried alluvium in paleo-channels. Overall surface soils and strata appear suitable for small disposal pits with no risk to groundwater away from the river.

Richmond Shire

Around the township of Richmond, there are few bores probably due to the depth to the water table of about 220–300 metres in layered sandstone and mudstone strata. Existing borehole soil stratigraphy and water table data suggest that the aquifers in use are similar in nature, as follows:

  • Thick layers of variable clayey surface soils to 13–30 metres.
  • Depth to useful aquifer generally deep at about 300 metres in sandstone. Static water levels of 30–50 metres and water temperature of 40°C suggest an artesian source.
  • Aquifer confined with static water levels probably rising under hydrostatic pressure.
  • The aquifer being in porous strata including sandstone overlain by various impervious units of rock, shale and clays.

Overall surface soils and strata appear suitable for small disposal pits with no risk to groundwater.

Winton Shire

Carcasses are known to be distributed widely across Winton Shire with no significant hazards from carcasses close to the township so nominal locations across the shire have been assessed for soil conditions.

NorthWirilla area

  • Thick layers of variable clayey surface soils to 20 metres.
  • Depth to shallow aquifer from 20-40m in places and others deeper at about 100-270m metres in shale, sandstones and siltstones.
  • Aquifer confined by overlying impervious strata with static water levels probably rising under hydrostatic pressure especially in the deeper aquifers.

SouthOpalton area

  • Surface soils variable according to location with clay, sand, shale and rock.
  • Some shallow aquifers in use in shallow unconfined aquifers at 10-15 meters with a deeper semi confined aquifer at 20-60m in sandstone and gravel beds in places. Other very deep aquifers at about 1,000m likely to be artesian.

Caution should be exercised when excavating near waterways for larger disposal pits when encountering sandy porous layers that may connect to beneficial uses of the connected shallow aquifer locally. Local information on nearby bores and wells may be useful. Otherwise seek local site specific information.

EastBonnie Downs/Lucella area

Limited information from borelogs on surface strata, variable from clays to mudstones and siltstones. Aquifers at 30-40m generally saline with few in use. Risks to aquifers probably low but local information should be sought on the occurrence of local, shallow, unconfined aquifers in use.

WestMiddleton/Lille area

Limited bores in use in the area as shown on database records but there may be local use of unconfined aquifers especially close to infiltration zones such as adjacent to water course.

  • Surface soils variable include clay lenses, sandy clays and sandstones.
  • Aquifers generally deep to very deep at 60m to 700m+ under significant artesian pressure.

Caution should be exercised when excavating near waterways for larger disposal pits when encountering sandy porous layers that may connect to beneficial uses of the connected shallow aquifer locally. Local information on nearby bores and wells may be useful. Otherwise seek local site specific information.

Diamantina—Dagworth area (SSE of Kynuna)

Very few bores shown as in use with aquifers where present very deep 800m to 1,000m under significant artesian pressure bringing water (hot) close to the ground surface. Clay and shale surface strata to significant depths.  Risk to artesian aquifers very low due to depth, confinement by upper impervious layers and outward water pressure.

Carpentaria Shire

Karumba

Groundwater bores and wells are limited in number and mainly located around the coastal fringe in shallow paleo-channel sandy sediments from buried riverine sediments.

  • Shallow unconfined aquifers at about 6m-8m.
  • Highly variable overlying sediment layers likely with sand, shell grit, clays and silts.
  • Deeper saline artesian aquifer at about 130m in sandy shale under confining shale and rock layers.

Sedimentary strata at any one location is likely to be highly variably over short distances due to the past variation in channel positions and sediment deposition that are now covered in more recent material. Test pits will be the only reliable way to determine the suitability of soils for disposal pits.  Information should be sought about the proximity of local wells and bores.

Neumayer Valley

No bores logged for the immediate vicinity. Likely to be similar to the western section of Augustus Downs with a deep artesian aquifer plus shallow unconfined aquifers around 20m, especially adjacent infiltration zones near waterways. Surface soils likely to be variable.

Normanton

Limited information on bores and aquifers. Shallow aquifer in sand at 10-12m very salty. Deeper aquifer at 65m to 70m in mudstones probably low yield, not in use. Surface strata likely to be locally variable between clays, silty sands, silty clays and gravel.

Several bores close to township on southwest side at the landfill site probably for leachate monitoring only with saline groundwater noted at about 15m. South west of the township (~30km) deep and very deep brackish aquifers occur at about 70m and 600m in shale and sandstone respectively.

Surface sedimentary strata at any one location is likely to be highly variably over short distances due to the past variation in channel positions and sediment deposition associated with the Norman River that are now covered in more recent material. Test pits will be the only reliable way to determine the suitability of soils for disposal pits.  Information should be sought about the proximity of local wells and bores.

Burke Shire

Burketown South/Yarrum

Very few bores shown as in use with aquifers where present very deep at about 600m in sandstone strata under significant artesian pressure bringing water close to the ground surface. Surface alluvial soils with clay to significant depths likely. Local variation in surface soils likely depending on proximity to waterways and drainage lines.

Floraville/Millar Creek

Limited information on bores and aquifers. Shallow aquifers at about 18m in shale and deeper saline artesian aquifer at about 580m in sandstone. Surface soils variable alluvial silty and sandy to sandy clay and clay.

Augustus Downs/Planet Creek

Very limited information on bores and aquifers. West side of river black soils, sand, shale and clay variable surface strata. Shallow aquifers likely at 15m to 20m with brackish to saline deep artesian aquifer in sandstone at about 330m to 400m under confining shale, sandstone and other rock strata.  East of the river an artesian aquifer occurs at about 500m with a shallower aquifer at about 45m.

Local variation in surface soils is likely depending on proximity to waterways and drainage lines.

For other locations not listed

Information for other urban locations not listed above can be readily produced.

Requests for this information should be sent to the Local Disaster Management Group for progression to Department of Environment and Science.

Required information will need to include GPS coordinates or a Real Property Description i.e. Lot on Plan.