Composting Animal Carcasses Removed from Roads: An Analysis of Pathogen Destruction and Leachate Constituents in Deer Mortality Static Windrow Composting

More than 48,700 deer-vehicle collisions occurred in Virginia from 2010 through 2011, the fifth highest number in all U.S. states. The Virginia Department of Transportation (VDOT) is responsible for the removal and disposal of animal carcasses along the state road system. The predominant methods currently used (landfill and burial) have several costly disadvantages, including long travel distances to landfills, increasing landfill restrictions, and lack of viable burial areas. Other states have found static compost windrows to be an easy and cost-effective carcass management technique. Deer mortality static compost windrows were monitored for 1 year under conditions typical of a VDOT area maintenance headquarters facility. Windrows were analyzed for pathogen destruction and the degree to which underlying soil filtered leachate contaminants. In response to high windrow temperatures, indicator pathogens E. coli, Salmonella were reduced by 99.99% the first sampling day (Day 7) and ascarids were deemed non-viable by Day 77. Soil filtration of leachate was effective in reducing concentrations of ammonia, chloride, and total organic carbon. Nitrate, a contaminant of particular regulatory concern, had an estimated mass contaminant loss of 1.9 lb/acre, compared to the 8 to 45 lb/acre estimated loss from fertilizer application on agronomic crops in Virginia. Results from this study indicate that with properly constructed static compost windrows, (1) high temperatures destroy indicator pathogens; (2) the natural filtration of leachate through soil reduces deer mortality contaminant concentrations; and (3) the low volume of leachate from windrows results in nominal losses of nitrate and other contaminants. The study recommends that VDOT consider sharing these results with the Virginia Department of Environmental Quality to discuss options for a statewide composting program. This could provide VDOT with an additional carcass management option.