Approximately 2.5 million miles of pipelines transverse the United States carrying hazardous liquids and natural gas from producing wells to end users (residences and businesses). Many of these pipeline networks are aging while others such as natural gas gathering pipelines remain largerly unregulated. Moreover, development has encroached on many of pipelines that were formerly located in rural areas, thereby increasing the risks posed by these pipelines.
Pipeline safety has been drawing increasing scrutiny from Congress. The “Pipeline Safety Improvement Act of 2002” required PHMSA to develop its risk-based integrity management program for transmission pipelines. Under the “Pipeline Inspection, Protection, Enforcement, and Safety Act of 2006,” PHMSA also establish minimum standards for integrity management for distribution pipeline networks. Under the rules developed by PHMSA, all distribution pipelines are considered to be in high-consequence areas because they are largely located in populated areas. As a result, distribution integrity management requirements apply to all distribution pipelines. However, the distribution pipeline rules tend to be less prescriptive than those for transmission lines due to the lower operating pressures. Congress recently mandated that DOT review the sufficiency of existing federal and state laws and regulations to ensure the safety of hazardous liquid and gas gathering pipelines under the “Pipeline Safety, Regulatory Certainty, and Job Creation Act of 2011.”
Despite the pervasiveness of pipelines, these structures are often not flagged or discussed in due diligence. A recent report by the GAO (“Collecting Data and Sharing Information on Federally Unregulated Gathering Pipelines Could Help Enhance Safety”; http://www.gao.gov/products/GAO-12-388) discusses the need for additional information about the pipelines used to collect natural gas from fracking operations.
The GAO indicated there are three main types of pipelines: Gathering, Transmission, and Distribution Pipelines
- Gathering pipelines- Gas gathering pipelines collect natural gas from production areas, while hazardous liquid gathering pipelines collect oil and other petroleum products. These pipelines then typically transport the products to processing facilities, which in turn refine and send the products to transmission pipelines. According to PHMSA gathering pipelines range in diameter from about 2 to 12 inches and operate at pressures that range from about 5 to 800 pounds per square inch (psi). These pipelines tend to be located in rural areas but can also be located in urban areas. PHMSA estimates there are 200,000 miles of gas gathering pipelines and 30,000 to 40,000 miles of hazardous liquid gathering pipelines. PHMSA does not regulate most gathering pipelines in theUnited States. For example, PHMSA regulates roughly 20,000 miles out of the more than 200,000 estimated miles of natural gas gathering pipelines. Similarly, PHMSA regulates only about 4,000 miles of the 30,000 to 40,000 estimated miles of hazardous liquid gathering pipelines.
- Transmission pipelines- PHMSA has estimated there are more than 400,000 miles of gas and hazardous liquid transmission pipelines. These pipelines can carry product over hundreds of miles, to communities and large-volume users (e.g., factories). Compressor stations maintain product pressure in natural gas pipelines while pumping stations maintain product flow for hazardous liquid transmission pipelines. Transmission pipelines tend to have the largest diameters and pressures of any type of pipeline, generally ranging from 12 inches to 42 inches in diameter and operating at pressures ranging from 400 to 1440 psi.
- Distribution pipelines- PHMSA has estimated there are roughly 2 million miles of distribution pipelines which transport natural gas from the transmission pipelines to residential, commercial, and industrial customers. These pipelines tend to be smaller, sometimes less than 1 inch in diameter, and operate at lower pressures—0.25 to 100 psi.
The Department of Transportation’s (DOT) Pipeline and Hazardous Materials Safety Administration (PHMSA) has established uniform, minimum safety standards that establish specifications for the design, construction, testing, inspection, operation, and maintenance of pipelines. The PHMSA regulatory program uses a four-tier classification system based on their proximity to populated and environmentally sensitive areas. Class 1 involves offshore areas. Class 2 includes locations with 10-45 buildings intended for human occupancy that are within 220 yards of the center line of the pipeline. A class 3 location is an area with more than 46 buildings intended for human occupancy that are within 220 yards of a pipeline or an area where the pipeline lies within 100 yards of either a building or a outside area such as a playground that is occupied by 20 or more persons at least 5 days a week for 10 weeks in any 12-month period. Class 4 locations where unit buildings with four or more stories above ground are prevalent
In addition, PHMSA has developed supplemental risk-based regulatory program termed “integrity management” for hazardous liquid and natural gas transmission pipelines and natural gas distribution pipelines in “high-consequence areas” where an incident would have greater consequences for public safety or the environment. Pipeline operators are required to systematically identify and mitigate risks to pipeline segments located in high-consequence areas, which are defined differently for the three types of pipelines.
For hazardous liquid pipelines, high-consequence areas include areas of highly populated areas, other populated areas, navigable waterways, and areas unusually sensitive to environmental damage. For natural gas transmission pipelines, high-consequence areas include highly populated or frequently used areas, such as parks. Most natural gas distribution pipelines would generally be considered to be in high-consequence areas since they are typically located in highly populated areas. High-consequence areas can be in Class 1, 2, 3, or 4 locations.
States may be authorized to conduct inspections for interstate pipelines, as well as inspections and associated enforcement for intrastate pipelines. State pipeline safety offices are allowed to issue regulations supplementing or extending federal regulations, but these state regulations must be at least as stringent as the minimum federal regulations. If a state wants to issue regulations that apply to pipelines that PHMSA does not regulate, such as unregulated gathering pipelines, it must do so under its own (state) authority. According to GAO, only 3 of the 39 state agencies interviewed reported that they collect and analyze comprehensive pipeline spill and release data on federally unregulated pipelines.
According to GAO, leading causes for leaks and spills from transmission lines is corrosion while excavation is the most common cause of damage to distribution lines. Because of their relative low pressure, damaged distribution lines tend to develop slow leaks instead of explosions. However, undetected gas from slow leaks can migrate long distance along utilities and sewer lines and accumulate in homes where inadvertent ignition could lead to fire or explosion.
GAO said states identified the following risk factors for pipelines:
- Construction quality- GAO said that state agencies reported the construction is critical to ensure the long-term integrity of the pipeline because the installation methods and materials used in pipeline construction affect the pipeline’s resistance to deterioration over time. For example, regulated pipelines may not be installed unless they have been visually inspected at the site of installation.
- Maintenance practices-State agencies said periodic maintenance including inspecting and testing equipment is important to prevent leaks and ruptures. Unfortunately, there are no such federal requirements unregulated gathering pipelines.
- Location-State and local safety agencies may not know or may be uncertain about the locations and mileage of unregulated pipeline infrastructure. This information is particularly useful for “Call Before You Dig” programs operated by states and localities. If unregulated gathering pipelines are unmarked and program officials do not know the location of the pipelines, businesses and citizens may damage a pipeline during excavation, which could result in fatalities, injuries, or damage to property or the environment as well as the shutting down of the pipeline for repair.
- Pipeline integrity– As previously mentioned, the leading risks to pipeline integrity is excavation damage and corrosion. Although states reported that excavation damage to a pipeline from nearby digging activities was the leading cause of pipeline incidents, many state agencies told GAO they often did not know or had limited knowledge about the integrity of unregulated gathering pipelines, thus increasing the potential for such damage. GAO reported that corrosion was reported as the cause of about 60% of regulated gas gathering pipeline incidents from 2004 to 2010. However, there is limited information on the integrity of unregulated gathering pipelines to assess the internal and external condition of these pipelines.
- Land Use Changes-State pipeline safety agencies also told GAO that increased urbanization that results in encroachment on existing pipeline rights-of- way is a moderate or high risk factor. For example, GAO reported stated that although a new housing or business development can change a location’s designation from Class 1 to a higher class that would then fall under PHMSA’s jurisdiction, the operator may not be aware of the development and therefore would not monitor and apply more stringent regulations along that pipeline.
- Increased extraction of oil and gas from shale deposits– GAO said this activity accounted for 16% of the total domestic natural gas supply in 2009 and is projected to increase to approximately 47% by 2035. As a result, state and federal safety officials have identified new gathering pipelines related to shale development as a potential public safety risk since these pipelines tend to have larger diameters and operate at higher pressures that traditional transmission pipelines. Such information can be used to help reduce future incidents.