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Safety and Public Awareness / PCB Overview

Date Requested: Jul 22 2019 5:03 AM
Printable Version

What are PCBs?

Polychlorinated biphenyls (PCBs) belong to a broad family of organic chemicals known as chlorinated hydrocarbons. The commercial production of PCBs began in 1929. PCBs were widely used as ingredients in the manufacture of heat transfer fluids, hydraulic fluids and dyes and as cooling and dielectric fluids in electrical transformers, light ballasts and electrical capacitors.

In the 1970s, Congress banned PCBs following a study that observed the effect of PCBs on mice, concluding PCBs could pose a threat to human health and the environment. As a result of the ban, PCBs were last manufactured on an industrial scale in the U.S. in 1979.

Through the normal course of a natural gas pipeline system’s operation, pipeline liquids, mostly in the form of hydrocarbons, can drop out of the gas stream and accumulate throughout a pipeline network. Some of these liquids may contain PCBs. Until 1979, there were many sources of PCBs in the natural gas pipeline industry. Some pipeline companies used a valve sealant that contained PCBs, some used turbine oil that contained PCBs, and some fogged their lines with waste oil that contained PCBs.

What is Northern doing to control PCBs in the pipeline system?

Northern has been installing filters where liquids are found. When these liquids are captured, the PCBs are captured with the liquids. Northern is pigging many its lines to remove liquids that may be present in the system. Northern has had a PCB management program in place since 1981. This program includes annual sampling at several liquid collection points and installing liquid collection appurtenances where required. Controlling the liquid movement throughout the pipeline system controls the migration of PCBs.


Contact for more information

If you have additional questions regarding PCBs, please email or call your account representative or contact michael.loeffler@nngco.com

PCB - Fast Facts
  • PCBs have been studied for nearly three decades.
  • As a result of these studies, the U.S. Food and Drug Administration, the Environmental Protection Agency and other federal agencies have established allowable concentrations of PCBs for food products, food grain for animals, oil concentrations, and other products.
  • A great amount of time and money have been spent studying the health effects of PCBs. These studies have not been able to definitively correlate PCBs to any form of cancer for people exposed in the workplace.
  • Studies show that PCBs travel in liquid form; therefore, PCB concentration in a dry gas stream is negligible. End users, such as residents and businesses, do not receive liquids in their natural gas; therefore, they are not exposed to PCBs from normal natural gas usage.
  • Manufacturing of PCBs was ceased in 1979. Prior to 1979, PCBs were introduced in the pipeline industry as a constituent of valve sealant and turbine oil. Northern did not use turbine oil with PCBs; however, Northern may have received this type of oil into its pipeline system through its interconnections with other pipeline companies.
  • The gas system in Northern’s market area is defined as a dry system (very little produced condensate). However, liquids are sporadically found in the pipelines for various reasons. For example, when gas cools down and the pressure is reduced, a minimal amount of liquids associated with the gas may collect in the pipelines. There are also residual oils in the pipeline that can be stagnant for quite some time, and then travel down the pipeline when pressures increase
  • Northern’s pipeline system contains many liquid filters and knock-out drips. However, research has shown that even if PCB contaminated oils were to reach a burner tip at an industrial facility, the PCBs would burn with the oil (at approximately 700 F). Incomplete combustion constituents are minimal, if detectable.
PCB - History and Overview
History of PCBs in the natural gas pipeline industry​

Pipeline liquids include pipeline condensate and other liquids that were intentionally or accidentally added to the pipeline. Pipeline condensates, primarily composed of hydrocarbon distillates, occur as a result of the movement of pressurized natural gas through a pipeline under varying temperature conditions. At one time, there were liquids that were intentionally added to natural gas pipelines; these included methanol as an ice hydrate deterrent; inhibitor chemicals for corrosion protection; and waste oils sprayed into a pipeline (known as fogging the lines) for gasket protection. Intentionally adding liquids to the pipeline is no longer a common practice in the industry.

In January 1981, PCBs were discovered in some natural gas pipeline liquids in Long Island, New York. Due to the discovery of PCBs, the federal Environmental Protection Agency, state agencies and the natural gas pipeline industry formed a task force to address the PCB problem and to coordinate national activities. Under this task force, the EPA took responsibility for addressing the PCB problem in major interstate natural gas transmission companies, while the EPA regions were tasked with coordinating with state commissions and local distribution companies. Extensive sampling of the major transmission facilities found 13 companies with PCB contamination greater than 50 parts per million (ppm), a rate high enough to cause concern. PCB pipeline liquids contamination also was found at a number of local distribution companies.

In late 1981 - more than 30 years ago - the EPA instituted a Compliance Monitoring Program (CMP) for the pipelines found to have PCBs greater than 50 ppm. The 1981 CMP required each company to develop remedial plans with four basic objectives: (1) ensure the proper storage and disposal of PCBs; (2) contain PCB contamination to limited areas of the transmission system; (3) eliminate any further entry of PCBs into the pipeline system; and (4) remove remaining PCB contamination from the pipeline system. To achieve these objectives, most of the participants installed filter separators to collect condensate at several locations along their respective pipeline systems.

In addition, each company was asked to develop and submit PCB monitoring plans that included sampling key points within the contaminated area. Suggested sampling locations included pipeline interconnections with major natural gas purchasers, and large volume condensate collection points. Individual monitoring plans were finalized with each company by early 1982.

The EPA required the pipelines to participate in an EPA compliance monitoring program. All companies were required to comply with all other aspects of the PCB rule, which included marking, record keeping and disposal.

In 1992, Northern requested the EPA to declassify the southern portion of its pipeline system from the CMP because PCB levels were either low or non-existent. The southern portion of the pipeline system consists of the pipeline south of the Beatrice, Nebraska, compressor station. Northern’s request was granted June 24, 1992.

In 1998, the EPA issued the Mega Rule, which addressed how pipelines were to handle PCBs. In order to manage the PCBs remaining in the pipeline system, natural gas transmission companies were required to comply with sampling and characterization requirements.

In 1999, following the installation of the Mega Rule, Northern sampled all PCB sources within its pipeline. These sources included natural gas compressors, natural gas scrubbers, natural gas filters, interconnects with other natural gas transmission companies, and pipeline liquid tanks and drips. The sampling has been repeated in subsequent years.

Characteristics of PCBs in the gas stream

A study published by the Gas Research Institute in 2001 indicated that PCBs travel through a pipeline in liquid form. Therefore, the study concluded, if liquids in the pipelines are controlled, the PCBs will be controlled. When the gas stream drops in pressure and velocity, the liquids fall out and remain in the pipeline. Accordingly, gas delivered to residential homes should not have liquids entrained in the gas. Any liquids will drop out prior to reaching the resident’s home.

PCBs in Northern Natural Gas' pipeline system

The PCBs found in Northern's pipelines entered the system many years ago. This is known because PCB use was discontinued in 1979. There are two types of PCBs that have been found in Northern's system. One type of PCB is from a turbine oil, which Northern suspects was delivered into Northern’s system from another pipeline company through an interconnection. Northern did not use turbine oil that contained PCBs. The other type of PCB is from valve sealant that Northern used in its pipeline system on segments north of Beatrice, Nebraska.

The valve sealant can enter the pipeline through the course of normal maintenance of the valves. Northern immediately ceased using valve sealant containing PCBs in 1979 when the EPA determined there were risks to public health.

Liquids that are introduced into the system through normal maintenance of the compressors travel downstream the pipeline in the gas stream and can pick up the PCB-contaminated valve sealant. To address this situation, Northern treats all of its liquids found north of the Beatrice station as PCB-contaminated, and follows all applicable regulations to test and remediate the presence of PCBs.

Northern rarely finds liquids that have concentrations above EPA's threshold levels that require the liquids to be treated as PCB-contaminated. Most of the liquids collected on Northern's system are well below these limits. Therefore, Northern handles the liquid wastes as it does used oil.

In the rare event that the liquids test above EPA's threshold level, the waste is disposed of properly, and the required testing and sampling is conducted according to the regulations.

Northern is focusing on removing these liquids from the system by using various types of equipment such as separators, drips and coalescing filters. The type of equipment chosen depends on the size of the pipeline and the range of the gas stream velocity. Northern also is removing liquids by pigging the lines throughout the northern half of the system. These pigs will sweep the existing liquids out through the pig receiver.

These filter installations and pig runs are ongoing and will continue to be performed to remove liquids and any PCBs from the system.

Health effects of exposure to PCBs

The primary routes of human exposure to PCBs are through ingestion and contact with the skin. The release of PCBs from prior industrial uses, beyond the pipeline industry, and the historical persistence of the compounds in the environment resulted in widespread contamination of water and soil, with subsequent potential exposure to the general population.

The initial adverse findings regarding the health effects of exposure to PCBs led to the creation of the complex PCB regulatory scheme in place today.

In 1996, the EPA reduced the toxic potency factor of PCBs after the EPA issued a draft PCB cancer reassessment. EPA's development of a revised PCB toxic potency factor and the evaluation of the non-cancer effects of PCBs continue today.

In March 1999, researcher Renate Kimbrough, who first found the link between PCBs and cancer in laboratory rats, issued a comprehensive study finding no significant increase in cancer deaths among workers who were exposed to PCBs on the job. (USWAG; June 30, 2003; PCB Health Effects)

In December 2001, a comprehensive report, "A Weight-of-Evidence Review of the Human Studies of the Potential Cancer Effects of PCBs" was submitted to the EPA urging the agency to re-examine the human cancer risks of PCBs. The report concludes that evidence demonstrates that exposure to PCBs is not a risk factor for breast cancer, that there is little credible evidence that PCBs have caused cancer in highly occupationally exposed workers, and that it is not evident that PCBs could cause cancer in humans at environmental exposure levels. Additional studies can be found at the websites listed below.

Frequently Asked Questions
Is natural gas safe to use for cooking and for heat?

Studies conducted by the Gas Research Institute conclude that as the velocity and pressure of transported natural gas decreases, as it does when supplied to end users such as residences, any liquids present will fall out prior to reaching the burner tip. For industrial customers, if liquids do reach the burner tip, the PCBs will burn if the burner tip is at or above approximately 700 F. The incomplete combustion of PCBs is minimal and is not considered a health effect.

What should I do if I discover oil in our line?

If oil is discovered in your natural gas line, you may contact your representative at Northern or you can call the Operations Communication Center at 1-888-367-6671. This information will be passed on to the operating personnel that will quickly act on this issue.

How do I protect my employees from PCBs if they are working near pipeline liquids?

Northern assumes, as a cautious safety measure, that all liquids north of the Beatrice compressor station contain PCBs. Northern has written PCB handling procedures requiring employees to wear appropriate personal protective equipment. If liquids come in contact with an employee’s skin, the employees should be instructed to wash the contacted area with soap and water.



    As noted in this document, the health studies cannot definitively correlate occupational exposure to PCBs with any type of cancer.

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