Aboveground surveys can be used to search for evidence of leakage of buried pressure pipelines. These listen, look or monitor for any telltale signatures of leaks. The types of leak signatures possible depend on the nature of the pipeline and product transported. Examples include acoustic evidence of leaks from pressure pipelines, thermal effects from steam or hot water pipelines, vegetation changes (killed or more lush) and the presence of chemicals from the pipeline in the air or water environment near the pipeline. According to the nature and extent of the survey and the land use associated with the utility right-of-way, surveys may be able to be undertaken as aerial surveys, vehicle-based surveys, foot-traffic surveys or as discrete monitoring locations.