Risk assessment involving the land disposal of animal waste on Central Texas dairies

Abstract

Land disposal of animal waste is an increasing problem for dairies in central Texas Once isolated, many producers now and themselves surrounded by towns and subdivisions. Many of these new neighbors are showing an increasing concern about potential nutrient pollution of surface and subsurface water supplies by improper handling of nutrient waste generated by dairies. This thesis attempts to explore this problem through the use of probabilistic risk assessment. This project assessed risks associated with nutrient disposal on two central Texas dairies. Risks were identified by using producer and researcher knowledge to create graphic representations of the disposal systems. These representations, known as event and fault trees, were used in conjunction with regular monitoring of nutrient inputs and outputs associated with the disposal systems to determine probabilities of nutrient escape past the boundaries of each dairy. Samples obtained during a runoff generating rainfall event were analyzed for nutrient content.