INTRODUCTION The American Petroleum Institute has prepared this report to provide both theoretical background and general operating procedures for persons who may at some point be required to deal with oil spilled on land. The report is designed for the man in the field; the reader who wants more detail will find a number of references cited. Despite the extensive preventive measures taken by the petroleum industry and others@ petroleum and petroleum products do escape on land from time to time. When they do so@ rapid and informed action may be required to minimize fire and explosion hazards and to prevent or minimize contamination of soil and ground water. The action taken will benefit from some son of contingency plan@ since the people on the scene must react rapidly to a spill. This is especially so in the initial stales. when the extent of the contamination and the potential hazards may not yet be clear. Hydrocarbons can escape to the environment in such a variety of circumstances. however@ that no plan can cover them all. Thus the man OD the scene must have sufficient background to be able to assess with some knowledge the situation that be faces and to sell the most effective courses of action. To provide that background@ this report considers both principles and practice each of six broad aspects of the problem. ? Fire hazards and safety procedures. ? Migration of oil products in soil and ground water. ? Recovery and control of spilled oil. ? Methods@ of identifying oil products. ? Biological degradation of hydrocarbons. ? Experience with actual oil spills. Fire Hazards and Safety Procedures Petroleum and petroleum products that escape on land create three potential hazards: fire and explosion: contamination of ground water supply; and damage to the environment. The risk of fire and explosion ordinarily will be reduced by rapidly assessing the potential hazard@ isolating the danger area@ eliminating sources of ignition@ ventilating confined areas@ and sealing off points of entry of liquid or vapor@ Procedures for preventing and correcting contamination of ground water are more complex and may vary appreciably from locale to locale. Migration of Oil Products The movement of petroleum products in soil varies with the volume of the product@ the physical properties of the product@ the structure of the subsoil@ the nature of the ground water system@ and the weather. Experience in the U.S. and abroad has emphasized the wisdom of securing advance information on soil properties and ground water systems in areas which may be subject to spills. The mechanisms of migration are complex@ but where sufficient data are available it is possible to predict whether a liven amount of oil is likely to reach a water table or to estimate the depth to which it is likely to migrate in the soil. When a large amount of hydrocarbon is involved@ skilled geological and hydrological help should be enlisted promptly. Recovery and Central Once finished petroleum products have escaped into soil and ground water@ it is usually necessary that they be contained and recovered. Prompt action@ based on some familiarity with the geology at the scene. may effectively reduce the consequences of the incident. The usual course of action. is to contain and remove the liquid hydrocarbon remaining at the surface. If a shallow water table is known to be present@ however@ it may be wile to spread the hydrocarbon near the surface. rather than to concentrate it and allow it to penetrate deeply enough at a local site to reach the water table. Other recovery and control measures include restoration of contaminated soil; removal of hydrocarbons from a water table with down-hole pumping equipment; general principles of selecting and using earth-moving and drilling equipment; construction of wells and ditches; and operation of pumping equipment. Method of Identification An essential requirement in dealing with oil spills on land is the ability to detect and identify the offending hydrocarbon@ Knowledge of the nature of the oil product involved can be vital@ for example@ in locating its source@ which may often be far from obvious. Care in taking samples in the field can be important to the validity of the results obtained in the laboratory@ where detailed analytical work generally will be done. This report contains information on sampling hydrocarbons in the field and cites a number of standard analytical methods for identifying petroleum products. Biological Degradation Microbes mainly bacteria will degrade hydrocarbons in the environment@ but their effectiveness depends on the maintenance of proper conditions. Biodegradation in soil is one method used currently to dispose of refinery wastes. The report outlines the principles involved@ which apply also to reconditioning soil that has been contaminated by oil. The possibility exists. moreover@ that biodegradation might be used to advantage to clean up hydrocarbons in subsurface soils and even in around water. Actual Oil Spills The report illustrates the state of the art by describing six actual oil spills on land and how they were handled by the people on the scene. Four of the incidents were among a number obtained by API in an extensive survey of the petroleum industry. All six were selected particularly to illustrate the principles and procedures described herein.