Road Kill Management

Composting road-killed carcasses

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. However, from experience handling animal mortalities on farms through on-site static pile composting, the composting of road-killed deer is also possible. These piles are easy to manage, do not generate odors, and the carcasses are transformed into compost in a matter of months. Our work not only addresses the composting process, but the hygienic quality of the process and product as well as worker health.

Previous NYSDOT practices included 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 practice is costly and inefficient and service providers do not always have a legal and environmentally sound plan for disposal. Contractors are paid between $50 and $80 per deer for pick-up and disposal, costing over $1 million annually. 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 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 an effective method of managing road killed animals. 

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.

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 woodchips.

There is a need to evaluate the effectiveness of static pile composting of mortalities bulked with woodchips.  Woodchips 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.  

Those responsible for managing animal mortalities need sound information and guidance on managing carcasses in static compost piles.  The NYSDOT and NYSDEC have 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. Field demonstrations are an effective means of sharing information, especially when used in combination with educational materials. 

Why Compost Road Kill?

• Pathogen kill occurs in thermophilic composts
• Can be done any time of the year, even when the ground is frozen
• Can be done using common highway equipment and readily available materials
• Relatively odor free
• All sizes of animals can be composted
• Relatively low labor and management needed
• Low cost

Steps to Composting Road Kill

1. Select Site. - select a site that is well drained and not subject to flooding. Depending on site topography, keep piles away from homes and businesses and from water courses, sinkholes, seasonal seeps or other landscape features that indicate the area is hydrologically sensitive.
2. Good Housekeeping. - site cleanliness is an important aspect of composting; it deters scavengers, helps control odors and keeps good neighbor relations.
3. Pile Building Prerequisites. - start with a hard surface made of asphalt, concrete or millings. Obtain a sufficient supply of fresh wood chips. Buy a compost thermometer. Have loader nearby. NYSDOT personnel should contact their Maintenance Environmental Coordinator.
4. Prepare Base. - lay a 24-inch bed of bulky, absorbent organic material; chips from tree chipping operations 2inches or larger work well. Ensure the base is large enough to allow for a 2-foot clearance around the carcasses on all sides. To promote air flow, do not drive on the compost bed or pile.
5. Build Pile. - lay animal(s) in the center of the bed. Lance the stomach if the carcass is bloated. Lancing to avoid bloating and possible explosion of the body cavity is optional. Explosive release of gases can result in odor problems and it will blow the cover material off the composting carcass. Place animals as shown. When adding a new animal to the windrow, pull back some of the wood chips that are covering the previously placed deer and place the new animal near the others. Small animals should be layered similar to stair steps.
6. Layer Animals. - with animals under 150 pounds, there can be 2 layers of animals with a 12-inch layer of wood chips in between. This seems to create conditions where the carbon and nitrogen levels are in balance and provides the mass needed to reach thermophilic temperatures. Animals over 150 pounds will be difficult to layer and they have enough mass to compost when enveloped in one layer of woodchips. Cover with 24inches of wood chips. The finished height should be 57 feet.
7. Large Animals. - with large animals (over 150 pounds or too heavy to lift to a second layer), cover a single layer of carcasses with 24-inches of wood chips.
8. Check Temperatures. - check temperatures to be sure the composting process is active. If deer are not frozen and the pile built properly, the temperatures should reach 120°-150°F (49°-65° C) in the first few days.
9. Let Site for 4 to 6 Months. - let sit for 4-6 months after the last carcass has been added and the pile gets hot (110°F), then check to see if the animals are degraded. Keep track of the pile start date and when the last animal is added.  If the compost process worked well you should find clean bones and some hair.
10. Reuse the Material. - reuse the material as a bed for additional carcass compost piles.
11. Use Compost on Roadsides. - allow the material to age for a year from when the pile got hot. After a year, remove large bones and use the compost in roadside maintenance or establishment projects. The bones can be used in the base of the next pile.