Introduction
Bioremediation of oil spills has been studied extensively over the past thirty years. This is a process in which naturally occurring microorganisms consume the oil and produce CO2 and H2O as by-products (Biederbeck, 1993, Bleckman, 1989). After the Exxon Valdez disaster in 1989, large amounts of money were allocated for study of cleanup efforts to help environmental efforts throughout the world (EPA, 1990). During that time, studies were also undertaken to determine if bioremediation would be useful in the disposal of oilfield wastes. One such waste product is the material found in the bottoms of oilfield storage tanks. This material, known as tank bottoms, is a mixture of crude oil, salt water, sand, and scale from the tank itself. It is not saleable material and must be disposed of in an environmentally safe manner. Tank bottoms are commonly shipped to and stored in hazardous waste landfills. This disposal method is expensive, and these landfills may not be secure; lawsuits may be brought against companies long after materials have been buried.
Because of the cost and risk of disposing tank bottoms in landfills, a group of oil producers in the Williston Basin supported a study to look for an alternative solution. In 1994, the Energy Committee of the Chamber of Commerce of Williston, North Dakota initiated a project which was designed to demonstrate that tank bottoms could be spread on agricultural land and bioremediated so that crops could be subsequently planted. The Williston Research and Extension Center, an extension of the North Dakota State University Agricultural Research Station, in northwest North Dakota donated a portion of their land for the demonstration, and the North Dakota State Health Department granted permission to carry out the project.
It should be noted that the process of spreading waste oil on soil, or landfarming, has become a standard oil field practice and is commonly used to remediate spills or to dispose of waste oil. An oil company may utilize a designated area for spreading oil, but that land is not farmed. This study is distinctive in its effort to plant crops in agricultural test plots spread with waste oil. The intent of this project is to provide the North Dakota Industrial Commission and the North Dakota State Department of Health with information that will help set guidelines for Farmer/Operator contracts allowing tank bottom spreading on agricultural land near oil field tank batteries.