Composting Animal Mortality Removed from Roads: A Pilot Study of Rotary Drum and Forced Aeration Compost Vessels

About the report:

The Virginia Department of Transportation (VDOT) removes an estimated 55,000 deer carcasses from its roadways each year at a cost of more than $4 million per year.  Many VDOT maintenance facilities have a need for viable, environmentally compliant, and cost-effective carcass management strategies.  Disposal challenges include a decreasing availability of conventional disposal methods, such as landfills, and a lack of viable burial areas.  The purpose of this study was to evaluate two in-vessel composting systems to determine the utility of each as a carcass management option for VDOT.  The systems were a rotary drum system and a forced aeration bin system (forced air system).  Pilot projects were conducted to determine the utility of each system based on two factors: (1) whether the generated compost met a set of established composting criteria, including regulatory standards; and (2) whether the system performed well from an operational standpoint.  

A rotary drum system was installed at a VDOT maintenance facility and monitored for 163 days.  The generated compost met the established pathogen destruction criteria but was inconsistent with regard to meeting the temperature and moisture criteria. The operational performance of the system was also inconsistent.  The problems encountered may be preventable in future installations, but the system requires further evaluation to determine its utility as a means of animal mortality management for VDOT.  It is recommended that VDOT install a smaller rotary drum system at a selected maintenance facility and evaluate its performance when the lessons learned described in this study are applied.

A forced air system was installed at another VDOT maintenance facility and monitored for 274 days.  The generated compost met all established compost criteria (i.e., temperature, compost maturity, and pathogen destruction), and the system performed well from an operational standpoint.  This system is a useful means of animal mortality management for VDOT.  It is recommended that VDOT install several additional forced air system units at maintenance areas interested in this method of composting.

When the savings in disposal fees and travel costs from composting mortalities in a compost vessel rather than disposing of them at a facility are taken into account, the initial investment in a compost vessel would be offset in less than 5 years for maintenance facilities with particularly long drives to a disposal facility (25 to 40 miles).  This study will be followed by an in-depth study to evaluate the economics and logistics of in-vessel composting to complete the feasibility analysis of this method of animal mortality management for VDOT.  A composting guidance document will also be prepared to support the implementation of animal mortality composting at VDOT maintenance facilities.

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