Pathogen Analysis of New York State Department of Transportation Road Killed Deer Carcass Compost Facilities

Cornell Waste Management Institute

Project Description

Over 25,000 dead deer and numerous carcasses of other animals such as raccoons, coyote and fox are managed annually by the New York State Department of Transportation (NYSDOT).  NYSDOT maintains and operates a 15,656 mile highway system of interstates, expressways and collectors which comprises about 15 percent of NYS's total of 111,000 miles of highway.  The 25,000 dead deer managed annually by NYSDOT do not account for deer killed on county and local roads that must be managed by local highway departments. 

Disposal options for these carcasses are limited and appropriate disposal is expensive.  Carcasses are often left by the road or dumped into low areas.  Over the past several years, the Cornell Waste Management Institute (CWMI) has worked with dairy farms to manage mortalities through on-site static pile composting.  Workshops and demonstrations held at these sites have generated substantial interest in the process.  The NYS Department of Environmental Conservation (NYSDEC), local and regional Departments of Health, Soil and Water committees and Natural Resources Conservation Service (NRCS) staff have attended workshops and become familiar with the process.  Regional and local NYSDOT personnel have attended workshops and indicated interest in trying composting to manage road-killed deer.  In response, composting of road-killed deer is being piloted under CWMI guidance at several NYSDOT facilities in New York State where it seems to be working well.  These piles are easy to manage, do not generate odors, and the carcasses are transformed into compost in a matter of months.  However, questions remain about the hygienic quality of the process and product as well as about worker health.

Current NYSDOT practices include contracting with service providers to pick up and dispose of the animals, dragging animals further off the road or placing them in pits and depressions off road sides.  This is becoming costly and inefficient and service providers do not always have a legal and environmentally sound plan for disposal.  Contractors are paid between $30 and $80 per deer for pick-up and disposal (Rick McKeon, personal communication, NYSDOT) and in FY's 2000-2002 this totaled just over $1.1 million.  Landfills generally will not take carcasses and when they do it tends to be restricted, so the NYSDOT is left with limited and/or costly disposal options.

For years NYSDOT has been able to leave animals where they were killed or drag them to the side of the road.  In more populated areas disposal into a pit or in low areas was often practiced.  These methods are becoming less acceptable as rural areas become more populated and there is increased concern for environmental quality.  Water quality can become compromised when animals decompose on or below ground.  As carcasses are buried or put in ravines, there is a good chance that water quality will be affected and it could become a public health issue as pets and people may come in contact with the carcasses.  Soil and water regional water quality groups are concerned about the ground and surface water ramifications and may be interested in cooperating in piloting of static piles for carcass disposal in several regions.

Passively aerated static pile composting is proving to be a good method of managing these wastes.  It is simple, takes less time than dragging a carcass out back, uses equipment and materials used in daily operations and is cost effective.  This method helps protect ground and surface water by keeping the carcasses out of contact with water and by reducing pathogens in properly managed piles and it reduces nuisance and odors.

The effectiveness of inactivating pathogens through composting is generally assessed by monitoring the reduction in indicator organisms.  Salmonella and fecal coliform are the usual indicator organisms.  These are the organisms that the USEPA requires for evaluation of the hygienic quality of sewage sludges.  It is widely recognized that the sensitivity of different pathogenic organism to heat varies significantly and questions have been raised about the use of the current indicator organisms.  Evaluation of the effectiveness of static pile composting to inactivate pathogens in road-killed carcasses requires identification of the pathogens that might be present and analysis of their sensitivity to inactivation by heating.  That, combined with time/temperature data from the compost piles, will provide the information needed to assess the hygienic quality of the compost product.

Chronic Wasting Disease (CWD) is a prion disease that is of concern in wild populations. There is no evidence to show whether CWD would be killed in the composting process. Compost temperatures are not high enough to inactive prions, but it is possible that microbial and enzymatic activity could (Langeveld, et al; Kirill, et al.).  Whether or not composting inactivates prions, through the process of composting the mortalities would be collected and managed to prevent nuisances such as odor.  The compost would be much more amenable to incineration than the untreated carcasses if incineration were required.  It would also be a more esthetically acceptable material than carcasses.  Guidance materials developed for NYSDOT personnel will address CWD after consultation with the NYS Departments of Health and of Environmental Conservation.

Very little work has been done to assess the effectiveness of pathogen-kill in static pile mortality composting.  The reduction of pathogens through composting due to elevated temperatures and microbial competition has been documented for intensively managed (frequently turned) compost piles handling other types of wastes.  Even for turned piles, little information exists for carcass composts.  Some research done in Ohio suggests regularly turned compost piles containing carcasses adequately kills common bacterial and viral pathogens (Keener et al).

Composting mortalities in turned piles requires more labor, machinery and management than static pile composting, thus increasing costs.  It also provides the potential for release of odors if turned too early in the process.  Static pile mortality composting is a more easily managed technique.  By properly constructing the compost pile to allow for adequate natural aeration, mortality composting can be completed on intact animals with little or no turning.  The process appears to be effective if the animals are enclosed in chunky carbonaceous material such as wood chips.

There is a need to evaluate the effectiveness of static pile composting of mortalities bulked with wood chips.  Wood chips are an appropriate and easily available material for use in NYSDOT compost piles.  Temperatures achieved in static pile composting suggest an adequate degree and duration of high temperatures to significantly reduce the survival of many pathogenic organisms, at least in the core of the piles.  Preliminary investigations by CWMI at several piles in NYS indicate that temperatures of 140 degrees F are reached and that temperatures over 130 degrees are sustained for more than 6 weeks.  However, temperature and pathogen kill in static compost piles have not been studied to the extent needed to provide confidence.  Questions such as “What is the thermal stability/sensitivity of the pathogens that might be present in road-killed wildlife in NYS?”, “Are there worker health and safety issues?”, “When is the process finished?” and “Where can the finished product be used?” still need to be addressed.

NYSDOT and local highway department staff who work with carcasses need health and safety information pertaining not only to carcass-borne pathogens, but also on tick-borne diseases such as Lyme disease, Rocky Mountain Spotted Fever, babesiosis and ehrlichisosis.  Preliminary indications based on discussion with Vet College faculty indicate that ticks on deer have a relatively low infection rate at least for Lyme disease and that handling the carcasses would thus not be a major potential source of exposure.  Ehrlichiosis is known primarily in the southern U.S. but has been reported in NYS and babesiosis is rare and is mainly coastal.  However relevant data need to be gathered and assessed in order to develop appropriate guidance.  Such guidance might address the life cycle, feeding behavior and data regarding infection coupled with advice on practices to minimize the risks of exposure and infection.  This guidance would be relevant to all workers handling carcasses and not just to those engaged in composting. 

Those responsible for managing animal mortalities need sound information and guidance on managing carcasses in static compost piles.  Some guidance has been developed by NYSDOT Region 8 staff based on experience with some pilot piles.  The NYSDEC has also developed some materials and there are standards developed by the NRCS for farm mortality management that are relevant.  These provide a basis from which to work to develop materials based on the additional work proposed.  A fact sheet and posters developed as part of our work with on-farm mortalities will also provide useful input to developing guidance materials for composting of road-killed animals (these can be viewed and downloaded from:  Field demonstrations are an effective means of sharing information, especially when used in combination with educational materials available on the WWW and printed materials.  They provide a means of reaching not only those at NYSDOT who might implement composting, but also other interested parties such as local highway personnel, state and local environmental and health staff, soil and water staff and others.  Bringing these players together is helpful in avoiding potential conflicts based on misunderstanding of the process.

Scope of Services

Under CWMI guidance, six static compost piles will be established. Three will be at NYSDOT facilities across NYS and will serve as sites for demonstrations and monitoring. Three will be at a location selected by CWMI where more intensive monitoring can be carried out (these are the “research piles”).  All piles will contain several deer carcasses bedded in wood chips.  Pile design, construction (such as placement of carcasses) and dimensions will be the same for all piles.  The wood chips used in the 3 demonstration locations will be obtained locally.  The 3 research piles will be constructed using the same wood chips. The research piles will be comprised of 4 adult deer.  Indicator organisms will be placed by CWMI into the carcasses in the research piles in a manner that enables them to be recovered for sampling.  Use of nylon mesh bags containing substrate that has been seeded with the desired microorganism has been successfully used in compost research.

Training shall be provided by CWMI to NYSDOT maintenance personnel at the three NYSDOT demonstration locations to enable them to manage and monitor the piles.  Automated temperature probes shall be provided by CWMI.  Use of automated temperature monitoring devices at all 6 piles will enable us to collect data on the time/temperature profile of the piles, which is a key to pathogen inactivation.  Temperature probes shall be placed by CWMI in several areas within each compost pile including within one of the deer carcasses in each pile in order to determine what temperatures are achieved within the carcass.

Consultation with faculty at the Vet College, the Cornell Department of Natural Resources (DNR), NYSDEC, NYS Department of Health Services (NYSDOH), US Fish and Wildlife Service (USFWS), US Department of Agriculture (USDA) and the U.S. Environmental Protection Agency (USEPA) will help to identify the pathogens of concern in road-killed animals including deer, coyote, fox, raccoons, bear, moose, beaver as well as domestic dogs and cats.  CWMI has met with many of these parties over the past year to discuss composting of road-killed animals and have established relationships that will enable CWMI to work with them on this project.  (CWMI was asked to attend a USEPA hosted meeting to discuss the development of methods to manage disposal of mass mortalities such as experienced in Wisconsin where CWD resulted in the killing of a very large number of animals.)  CWMI is particularly fortunate to have excellent working relationships with the Vet faculty who are interested in this work and can provide us with assistance throughout the project.  Dr. Stehman and others shall provide advice concerning pathogen detection methodologies and indicator organisms as well as assistance in locating appropriate literature.  Once data have been collected, these experts shall contribute to the review and interpretation of results. 

A literature review shall be conducted by CWMI to find data concerning the thermal stability of the pathogens identified.  The results will be compared with data for pathogenic organisms present in sewage sludges to determine if those likely present in wildlife are more resistant than those present in sewage sludges.  The information and professional opinion will help to determine what pathogens or indicator organisms should be tested for in the composts.  It is suggested that Mycobacterium enterra and Geobacillus stearothermophilus may be appropriate indicators with which to seed the piles. 

Under the direction of CWMI, results shall be statistically analyzed and interpreted so that appropriate guidance can be developed.  Field demonstrations shall be conducted by CWMI at each NYSDOT demonstration site to share the information gained.  Guidance and educational materials shall be generated and disseminated and presentations shall be made to both to NYSDOT and to local NYS highway personnel. 


Reference cited:

Keener, H.M., D.L. Elwell, M.J. Monnin. Procedures and Equations for Sizing of Structures and Windrows for Composting Animal Mortalities. 2000. Applied Engineering in Agriculture 16(6): 681-692.


Langeveld, Jan P. M. Jeng-Jie Wang, Dick F. M., Van de Wiel, Giles C., Shih, G., Garssen, J., Bossers, A., and Shih, J. 2003. Enzymatic Degradation of Prion Protein in Brain Stem from Infected Cattle and Sheep. JID 188 (1 December). 1782


Tsiroulnikov, Kirill Human Rezai, Elisaveta Bonch-Osmolovskaya, Peter Nedkov, Adriana Gousterova, Valeä Rie Cueff, Anne Godfroy, Georges Barbier, Franc Ois Meätro, Jean-Marc Chobert, Pascal Clayette, Dominique Dormont, Jeanne Grosclaude, and Thomas Haertleä. 2004. Hydrolysis of the Amyloid Prion Protein and Nonpathogenic Meat and Bone Meal by Anaerobic Thermophilic Prokaryotes and Streptomyces Subspecies. J. Agric. Food Chem. 52, 6353-6360.