A MODIFIED DRASTIC MODEL FOR SITING CONFINED ANIMAL FEEDING OPERATIONS (CAFOS) IN WILLIAMS COUNTY, OHIO

Williams County in northwestern Ohio relies primarily upon shallow groundwater found in a sand and gravel glacial outwash aquifer as its primary source of drinking water. Aquifers composed of these media have a very high rate of groundwater flow, and thus transmit pollutants very easily. Williams County currently has three dairy CAFOs (Concentrated Animal Feeding Operations), with the possibility of a multi-million chicken egg-laying facility breaking ground soon.

CAFO livestock manure contains pathogens and contaminants and has been shown to be harmful to human health. CAFOs are one threat to the groundwater quality and quantity in the county as they generate tremendous volumes of manure on small areas of land. This manure is typically stored onsite in lagoons until applied on nearby fields as fertilizer. Breaches in manure storage lagoons, inadequate manure pit liners, and over-application to fields are a relatively common occurrence and they increase the risk of contaminating the underlying groundwater supplies. Currently, the siting of these facilities in the county involves a fairly simple geologic assessment that does not fully take pollution pathways into account.

In this study, DRASTIC, a groundwater pollution potential mapping model was modified to adequately display relative pollution potential from CAFOs. The modifications included adding a land-use parameter into DRASTIC and altering existing parameters such as removing topography and lowering the vadose zone to reflect lagoon settings. The soil media parameter was also more heavily weighted to represent land use management practices such as conservation tillage and soil structure preservation in areas where manure is applied. These modifications properly address how manure reacts when applied to the surface and how conventional CAFO methods of manure storage and processing are used. The results of this research will be used as a preliminary county-wide screening tool to evaluate the siting of CAFOs.