Oil and natural gas pipelines are broken down into three main varieties. There are gathering pipelines, transmission pipelines, and distribution pipelines. Gathering pipelines are defined by the Pipeline and Hazardous Material Safety Administration, PHMSA, as pipelines which transport the product from the original source (PHMSA, 2011b). Transmission pipelines are used to bring large quantities of processed product to communities and large-volume users (Government Accountability Office [GAO], 2012). Distribution pipelines come from a station where a transmission pipeline has fed the desired product, and deliver the product to residential and commercial users (GAO, 2012).
Gathering pipelines have garnered the most controversy from groups worried about the pipeline industry expanding out of control. In some sense, groups have a reason to worry. Ninety percent of gathering pipelines are defined as “Class 1,” the lowest classification of four. Class 1 pipelines are unregulated by the PHMSA because, in the case of failure, they are deemed to be “low-risk” to human life (Seville, 2014). Class 1 gathering lines, defined as less than 11 human-residency buildings per mile, are allowed to reach 72% of their stress level, the theoretical maximum amount of product flow a pipeline can handle, and have no federal laws that regard factors such as proximity to those houses and mandatory reporting of accidents along those lines. The most important accolade in the pipeline industry’s history is that transporting hazardous liquids, natural gas, and oil via pipeline is the safest method in terms of total injuries and lives lost compared to road or rail transportation (Seville, 2014). Due to economics and regulations, whenever possible, pipelines are better built in rural, lowpopulation areas with very little risk of causing injury to humans. These factors and others such as better procedures and materials have cut pipeline-related casualties by over 50% since 1991 to 2011 (PHMSA, 2011a).