EVALUATION OF RESIDUAL SOIL CONTAMINATION FROM COMMERCIAL OIL-WELL DRILLING ACTIVITIES AND ITS IMPACT ON THE NATURALLY-OCCURRING BACKGROUND-RADIATION ENVIRONMENT

Radiation exposure received by individuals living and working on a far mland contaminated with radium was evaluated by measuring the technolo gically enhanced radiation background using portable survey instrument s and a high-pressure ionization chamber. Analysis of selected organic compounds, metals, and radioactive material in samples of soil and wa ter obtained from the farm demonstrate a potential risk to inhabitants that needs to be evaluated, especially for future generations living and working on this land who may not be aware of the potential hazard. The distribution of radium and several other hazardous waste material s was found to be significantly elevated in areas where sludge ponds a nd waste pits were formerly located. Transport of these contaminants i n soil was detected by in situ measurement of radium, which may be a u seful analog for determining the translocation of metals and other con taminants associated with oil well-drilling activities. Conventional r isk assessment models, using default input parameters, assume that exp osure to radium in the soil is via the food chain and radon, and that inhalation of resuspended particles is less important. These models al so assume that the chemical and physical characteristics of the radium contamination remain constant in time. However, under certain environ mental conditions, the radium compounds will become more soluble with time, increasing their significance as a source of radiation exposure, especially as the radium will persist in soil for many thousands of y ears. Assessment of present and future risk to populations living and working on these contaminated lands must account for the potential cha nge in radium solubility with time and the increased risk from both in halation and ingestion of radium. This research describes environmenta l conditions found at one former well site in the Martha oil field in eastern Kentucky and identifies several important concerns related to the current and future risk associated with use of land contaminated w ith naturally occurring radioactive material.