Operating a pipeline requires an understanding of the purpose of the pipeline, how the pipeline was designed and constructed, the codes and standards that govern the operation of the pipeline, the operational history of the pipeline, and the pipeline's current status. Separately, the maintenance needs of the pipeline must be carefully assessed, and the schedule and procedure for maintenance must be clearly spelled out in a maintenance manual. A ground-penetrating radar is capable of detecting the spilled natural gas and petroleum that exists in the soil above the leak point of a buried pipeline. Both the mass-balance method and the pressure-drop method discussed have advantages and disadvantages, and have about the same accuracy and reliability. The kind of pipeline integrity management program preferred by industry is risk-based, which means giving highest attention to those items that present the highest risks.