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We use a wide array of diagnostic tools, preventive maintenance programs and oversight techniques to identify and mitigate potential issues long before they can become a problem. For example, our West Virginia operations have used one-call ticket data to reduce excavation damage 39 percent since 2014.
Dominion Energy’s more than 2,300 storage wells and reservoirs are designed to withstand fluctuating pressures associated with the injection and withdrawal of natural gas, season after season. Through regular inspections, we monitor the condition of the lining, or casing, that contains the storage pressure within the wellbores. Company wells contain up to three concentric linings. On many, the innermost casing is surrounded with cement from deep in the wellbore to the surface of the ground, to provide additional leak prevention.
Dominion Energy has been using electronic logging tools to inspect our storage wells since 1973, years before that technique was required by the Pipeline and Hazardous Materials Safety Administration (PHMSA). The process involves lowering a high-resolution electronic device into the well to take electromagnetic readings over its entire length. The readings provide important information regarding the condition of the well — information that is then used to determine what, if any, remedial work will be performed.
We perform well casing integrity inspections for internal and external corrosion. Through other regular inspections we verify well status and pressure, and look for signs of atmospheric corrosion, venting gas or leaks. These inspections are complemented by remote monitoring and monitoring of third-party drilling activities in and around our storage pools. And in the unlikely event of a major leak, the company has site-specific Emergency Plans for each storage field.
We have completed well casing inspections on more than 80 percent of our storage wells. We plan to expand the program each year, and to complete all inspections within the PHMSA-specified period of three to eight years. We take a variety of factors into account when deciding how often to inspect storage wells. Our documented risk-ranking program takes into account factors such as depth, operating pressure, and location. The program continues to evolve as technology advances, and based on our experience as a major storage operator.
Our integrity management process meets or exceeds the requirements of PHMSA rules regarding underground storage. The formal risk management strategy includes an initial evaluation of risk based on threats and consequences of potential events. Any significant risks are then addressed through the application of specific preventive and mitigation measures. The process includes feedback and validation measures for continual improvement. A capital budget is established each year for necessary repairs and improvements, such as replacing wellheads and casings, to reduce potential risk and keep the system operating efficiently.
In 2018, PHMSA began its first audits of storage facilities in the United States. Its audits of Dominion Energy’s program, and several of its storage facilities, produced no significant findings. Several more audits are scheduled for 2019.
The company’s leadership fosters a culture of integrity management. Our objective is to align with the spirit of the regulation, beyond basic compliance with the code. Dominion Energy supports pipeline integrity activities through written Integrity Management Programs, objective analysis and evaluation, and making performance improvements as necessary to manage risks. We have created a Transmission Integrity Management Program (TIMP) and a Distribution Integrity Management Program (DIMP) that meet or exceed PHMSA integrity management regulations.
Our transmission pipeline integrity management program addresses the following components:
- High-consequence areas;
- Threat identification and risk assessment;
- A baseline assessment plan;
- Remediation and prevention;
- Performance and quality assurance;
- Change management; and
The company inspects and assesses its transmission pipelines in numerous ways — including patrols and around-the-clock monitoring from Gas Control command centers. In addition to regular aerial observation and foot patrols, pipelines also are inspected from the inside with in-line tools that are often called “smart pigs.” These devices use computerized sensors capable of detecting and reporting anomalies such as dents and corrosion, enabling us to make appropriate repairs to ensure the integrity of the pipe. They are introduced at specialized launch sites, and move through the pipeline to downstream receiving locations. The data collected by these sensors is then analyzed to determine whether pipeline segments need replacement or repair. Dominion Energy uses smart pigs on more than half of its transmission and storage system — well beyond regulatory requirements.
Dominion Energy continuously monitors the flow of gas using remote sensors, which are placed along the entire length of a pipeline. Remote-controlled safety shutoff valves allow Gas Control operators to stop the flow of gas immediately and isolate individual sections of pipeline if necessary.
To prevent external corrosion, the company operates cathodic protection systems on our underground steel assets. In addition to annual monitoring at key locations, we perform detailed corrosion surveys for an average of 1,000 miles of transmission pipeline each year to confirm that these protection systems are functioning effectively.
We prevent internal corrosion through vigilant monitoring of constituents in the gas stream, evaluating potential impact of impurities, and applying targeted preventive and mitigating measures. The company also examines the internal and external surfaces of our assets whenever operating and maintenance activities provide such opportunities, to validate the effectiveness of our programs.
We have committed to replace 50 miles of bare transmission pipeline by 2020 across the Dominion Energy Transmission, Inc., system. We also have partnered with the industry to improve response times. To support this initiative, Dominion Energy has committed to install an additional 250 remote-controlled or automated valves across the Dominion Energy footprint by 2020.
Dominion Energy’s Distribution Integrity Management Program addresses the following elements:
- Knowledge of the distribution system;
- Threat identification;
- Evaluation and ranking of risk;
- Identification and implementation of measures to address risks;
- Measures of performance, monitoring of results, and evaluating effectiveness;
- Periodic evaluation and improvement;
- Reporting results; and
- Document and record retention.
The company maintains a number of other programs to ensure distribution pipeline safety as well.
- An enhanced excavation-monitoring program for high-risk excavation sites;
- A damage investigation program to conduct root-cause analysis of damage to pipes;
- An excavator communications and training program to inform the public and excavators about the importance of safe excavation practices;
- An enhanced leak survey program to accelerate leak surveys on higher-pressure distribution lines that are located outside of business districts; and
- A cross-bore verification program to investigate older pipeline projects that were directionally drilled prior to preventive procedures that are in place now.
Additional safety assessments for transmission and storage pipelines occur on both a cyclic and as-needed basis. This redundant system of vigilant monitoring enables Dominion Energy to detect and fix any problems in its system long before they present a hazard.
Pipeline Safety Management System
In addition to all of the foregoing, Dominion Energy also has implemented a Pipeline Safety Management System (PSMS). This is a voluntary program modeled on similar ones in other industries such as aviation and chemical manufacturing. The PSMS program takes a systematic and measurement-based approach to pipeline safety both across business units and within them, from top executives to field workers. The aim is to identify areas for improvement and share that information widely. This PSMS program is a never-ending journey for continuous safety improvement.
Several years ago Dominion Energy formed a steering committee to develop and implement the PSMS program and put it into place across Dominion Energy’s entire natural gas business. (This program was initiated prior to the acquisition of SCANA, and later will be extended to Dominion Energy’s Southeast Energy Group.) The first three elements of the PSMS program moved to the implementation phase in 2018. These three elements — leadership and management commitment, incident investigation and lessons learned, and emergency preparedness and response — have been tied to the company’s annual incentive package.
It is critically important that our customers, contractors and employees know how to take safety precautions around gas infrastructure. Given the widespread nature of our natural gas grid, the general public also plays a key part. Over the past 20 years, third–party damage has been the primary cause of incidents on natural gas pipelines. Dominion Energy conducts public awareness programs to educate landowners near company facilities, to reduce the likelihood of dig-ins or other harm that can cause a release of methane to the atmosphere.
In 2018, our Utah operations enhanced damage prevention by providing personnel to monitor excavation around large distribution lines, leading to a lower damage rate. Our West Virginia operations have used one-call ticket data to reduce excavation damage 39 percent since 2014.
The company has long supported laws requiring use of the 811 “Know what’s below. Call before you dig” one-call system. Anyone planning to do work that disturbs the soil beneath streets, sidewalks, yards, farms or other property is required to call the designated number. Utilities, authorities and others mark their underground facilities before work begins. Excavators can call a state one-call system or the national number: 811. These one-call programs are a valuable component to protect our system and to ensure safe operations.
Thanks in part to extensive safety measures, natural gas emergencies occur very rarely. Those that do often result from external factors, such as excavations carried out near underground pipelines without adequate precautions. Because the potential for emergencies still exists, our company has developed rigorous and comprehensive programs and policies to mitigate them.
Dominion Energy maintains and values positive, long-term relationships with fire departments, police departments, and sheriffs’ offices. We conduct annual public-liaison meetings with emergency-response agencies. We have installed remotely operated valves that can be closed when a pipeline leak or rupture occurs on a transmission pipeline. Compressor stations have similar emergency shutdown systems activated through manual controls. Those systems are tested at least annually.
We have developed response plans for a variety of contingencies that could affect pipelines, compressor stations and storage wells. When there is an emergency call related to our distribution infrastructure, our personnel are on-site within one hour at least 98 percent of the time.
These efforts have produced a strong safety record that has received industry recognition. In 2018, Dominion Energy Ohio received the American Gas Association’s Safety Achievement Award for excellence in employee safety for large local distribution companies, recognizing its 2017 performance. The company has won this award — the natural gas utility trade group’s highest employee safety honor — multiple times. Dominion Energy operations in Utah and West Virginia, as well as Dominion Energy Questar Pipeline and Dominion Energy Transmission, Inc., also received AGA Industry Leader in Accident Prevention awards for their performance in 2017.