Natural Gas System Frequently Asked Questions

General Pipeline Safety

Is there a transmission pipeline in my neighborhood?
PG&E is committed to providing you with information about the natural gas system that serves your community, neighborhood, home and business. In April 2011, PG&E sent letters and brochures with important information about natural gas safety to anyone who has a home or business located within about 2,000 feet of a gas transmission pipeline owned by PG&E. For information about any specific transmission pipeline in your neighborhood log in to your account to view a map online, or call us at 1-888-743-7431.

View a map that shows the location of all our gas transmission pipelines.

How do I know the transmission pipeline in my neighborhood is safe?
PG&E has a comprehensive inspection and monitoring program to address the safety of its natural gas transmission pipeline system. PG&E regularly conducts leak inspections, surveys, and patrols of all of our natural gas transmission pipelines. Any issues identified as a threat to public safety are immediately addressed. We do not delay or defer work that is necessary for public safety. We monitor our gas pipeline system operations 24 hours a day, seven days a week.

Who is PG&E working with to address the safety of the transmission pipeline system?
We are committed to earning our customers' confidence in the safety of our gas system, but we know we have a long way to go. While we have taken significant steps to improve the safety of our system since the San Bruno tragedy, we are committed to doing much more.

We are working under the oversight of regulatory agencies, including the California Public Utilities Commission (CPUC) and the U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration (PHMSA), as well as the National Transportation Safety Board (NTSB). Our work is continuing as we diligently review our records, and monitor, survey, and test pipelines throughout our entire natural gas pipeline system. Our top priority in 2011 and beyond is the safety of our natural gas system.

What are the steps PG&E has taken to enhance the safety of the pipelines since the San Bruno accident?
Since September 2010, PG&E has taken significant initial actions to improve the safety and operations of PG&E's natural gas system – and the safety of the communities we serve.

These include:

  • Substantially reduced the pressure on pipelines that had segments with characteristics similar to the San Bruno pipeline and that had not been pressure tested.
  • Conducted both an aerial and ground surveys of the entire natural gas transmission pipeline system
  • Launched a detailed pressure test records review and validation effort
  • Continued to share detailed information with public officials, emergency response agencies and customers about the locations of our pipelines.
  • Enlisted industry-leading experts to advise the company on risk management and pipeline integrity assessment.
  • Begun pressure testing pipeline segments and using new in-line inspection tools.
  • Conducting a comprehensive internal review of operating practices
  • Tightened locate, mark and dig requirements
  • Notified all customers and municipalities of their proximity to gas pipelines
  • Conducted practice drills with first responders

Why did you reduce pressure in some of your pipelines?
After the accident we substantially reduced the pressure on pipelines that had segments with characteristics similar to the San Bruno pipeline and that had not been pressure tested. This was performed as a near-term precautionary step until we can confirm the safety of these pipelines by other appropriate action.

Can reducing pressure impact service?
Pressure reduction can impact PG&E's ability to provide service to its customers on cold days when demand increases. Reduced pressure coupled with increased demand could result in outages. In a worst case scenario where outages are widespread, it could take days, weeks, maybe even months, for PG&E to relight all the pilot lights for customers and restore full service.

What are you doing to strengthen the natural gas transmission system? What else is PG&E going to do in the future?
On August 26 PG&E filed its Pipeline Safety Enhancement Plan (PSEP) which proposes its plan to enhance safety and improve its operations. The PSEP includes four key initiatives to strengthen its natural gas transmission system:

  • Pipeline Modernization: Strength testing all pipe segments (including those previously exempted by federal regulations), replacing segments that should be replaced, and retrofitting pipelines to allow state-of-the-art internal inspections, or "pigging"
  • Valve Automation: Expand the use of automated valves to isolate and minimize damage if any pipeline ruptures do occur and enhance electronic monitoring of the gas system to identify operational issues and prevent or quickly locate pipeline ruptures
  • Pipeline Records Integration: Transition away from traditional paper records and consolidating all of its gas transmission pipeline data into an integrated electronic data management system to strengthen system operations, maintenance, inspections and regulatory compliance
  • Interim Safety Enhancements: Immediate steps to enhance the safety prior to completing the work proposed within the plan.

What can I do to make myself / my family/ my employees safer?
There's safety in knowledge, so it's important we all:

  • Know the signs of trouble - smell, sight and sound.
  • Know what to do in case of an emergency - always leave the area and call 911 and PG&E at 1-800-743-5000.
  • Know what's below before you dig - call 811 for a free underground utility marking service.

What should I do if I smell gas?
For safety reasons, PG&E adds a sulfur-like rotten egg smell to natural gas. If you detect this odor make sure to follow these basic safety steps:

  • Keep a flashlight handy to investigate minor gas odors.
  • Never use matches or candles to look for gas leaks, and never turn any electric switches on or off if you suspect a gas leak.
  • Check pilot lights to see if they are lit.
  • If the smell of gas continues, or if you have any doubts, open windows and doors and get everyone out of the building.
  • Using a phone away from the building, call 9-1-1 and PG&E at
  • Remember: never attempt to handle the problem yourself - only PG&E crews are qualified to turn gas valves or restore neighborhood or household service.

Survey, Inspection and Testing

How do you survey and test pipelines?
We are committed to safety and continuously survey, monitor, and test our pipelines. Following the San Bruno tragedy, we launched an accelerated program and re-surveyed the entire natural gas transmission pipeline system. Teams of gas field technicians use both vehicle-mounted and special handheld leak detectors.

We inspect and test pipelines using a variety of methods, including pipeline "smart pig" devices equipped with sensors and cameras that travel the length of a pipeline (in-line inspection). We also conduct hydrostatic pressure testing, which involves charging the pipe with water at high pressures to safely reveal potential weaknesses as well as direct assessment by digging up pipeline sections.

What is direct assessment?
Direct Assessment is an effective tool used to identify potential coating damage, which is the first level of protection against lead-inducing external corrosion. This technology is also used to assess the current level of "cathodic" protection, which helps show the current and future health of the pipe. It can be performed on nearly any pipeline, regardless of diameter or configuration.

What is a leak survey?
Leak surveys are a way to identify problems in a gas transmission pipeline that could affect the integrity of the pipe or the operation of the transmission system. While PG&E performs regular annual leak surveys of transmission pipelines, we took extra steps after the San Bruno accident by conducting comprehensive ground and aerial leak surveys over the entire system. Leak surveys involve a variety of technologies ranging from combustible gas indicators to newer infrared and laser devices.

What is an in-line or internal pipeline inspection?
There are many internal line inspection, or in-line inspection (ILI), devices available that can be equipped with robotic cameras and sensors to check pipe thickness and welds while detecting flaws and corrosion. Although these "Smart Pigs" have been proven effective, their use is limited to pipelines designed to accommodate the units with proper insertion and extraction points, smooth transitions between pipe segments, minimum radius turns and the like. Many of PG&E's pipelines were designed and constructed before Smart Pig technology was developed and will require significant reconstruction to accommodate this form of inspection.

What is a hydrostatic test?
Hydrostatic testing is a proven method for verifying the actual capability of a natural gas pipeline to operate at a safe level of pressure (referred to as the maximum allowable operating pressure, or MAOP). Hydrostatic testing is also used to test such familiar items as scuba tanks, fire extinguishers and air compressor tanks. A hydrostatic test involves pressurizing a section of pipe with water up to a much higher percentage of the pipe material's maximum design strength than the pipe will ever operate at with natural gas. This verifies the capability of a pipeline to safely operate at the desired MAOP and can reveal weaknesses that could lead to defects and leaks in the pipe. In order to perform a hydrostatic test the pipeline has to be taken out of service for many days, which may impact our ability to serve our customers.

General Gas System Operations

What is the difference between a transmission pipeline and a distribution pipeline?
Transmission pipelines are generally larger and operate at a higher pressure than distribution pipelines. Transmission pipelines transport the natural gas from the compressor stations and storage facilities to regulators which reduce the pressure before reaching the distribution system. The distribution system feeds the smaller lines that deliver gas to individual businesses or residences.

What is the typical operating pressure of a Transmission line?
On PG&E's Gas Transmission Pipeline System Map, PG&E included any transmission pipeline operating at or above 60 psig (pounds per square inch gauge). This means that additional miles of pipeline are included on PG&E's online map that might not be included on other maps that use a different parameter or definition of a transmission pipeline.

Should I be concerned if the transmission pipeline in my community is more that 50 years old?
A properly maintained pipe can operate safely for 100 years or more. Although pipeline age is a relevant factor in reviewing the status of pipeline, it is not in itself a cause of concern.

What is Maximum Allowable Operating Pressure?
Federal law requires that we establish a Maximum Allowable Operating Pressure, or MAOP, for all pipeline systems. MAOP includes a wide margin of safety and is set at a fraction of the pipe's calculated strength, which is the minimum pressure at which the pipe is expected to begin deforming. For example, the MAOP for pipelines in areas with more than 45 homes within 220 yards per linear mile on either side of the pipeline is set at no more than half the pipe's calculated strength.

How is Maximum Allowable Operating Pressure (MAOP) determined?
MAOP is determined by one of three ways. First, MAOP can be determined by calculating the Specified Minimum Yield Strength, or SMYS, of the pipe. SMYS is the minimum pressure at which the pipe is expected to begin deforming. MAOP is then set at a fraction of the SMYS, thus allowing for a wide safety of margin. For example, MAOP is 50 percent or less for a pipeline in a more populated area. Second, MAOP can be set based upon pressure tests, where MAOP is set safely below the pressures used in the pressure test. Third, for pipe installed years ago, the MAOP can be based upon the pressure at which the pipeline has operated safely for years.

Who sets MAOP levels?
Federal law requires that pipeline operators establish MAOP for each section of pipeline or each distinct segment of a gas pipeline system.

How is pipeline pressure controlled?
PG&E controls pressure on its pipeline system through a series of safety measures, including pressure regulator stations and overpressure protection devices. These systems operate to keep pressure within specified limits. They are surveyed and maintained regularly. More information about how our natural gas system operates can be found here.

Do you have emergency equipment that allows automatic shutdown of pipes?
PG&E has hundreds of automatic over pressure protection control valves that protect pipelines and are activated if the pressure gets too high. PG&E also has some lines with rupture control valves for specific needs and the 24 hour control center has the ability to shut down some pipeline systems via remote control.

What is the difference between manual valves, automatic shut-off valves and remote controlled valves?
Manual valves can only be operated by a trained, federally-qualified individual at the valve location. Automatic shut-off valves are fully automated shut-off valves that will operate without human intervention when specific operating conditions on the pipeline arise. Remote-controlled valves can be remotely operated from a control center.

How is a valve turned off? What is the process?
The process is different for each type of valve: remote controlled, automatic, manual.

  • Remote controlled valves: these are valves operated by remote control from our 24-hour manned Gas Control Center
  • Automatic shut-off valves: these are valves with control programs triggered to operate via a specified change in pipeline conditions and do not require remote control or personnel on site
  • Manual valves: these are valves hand-operated by wheel and gear assembly or by wrench with an indicator to show whether it is open or closed

Are you planning to install new automatic shut-off and remote controlled valves?
PG&E will automate 29 valves (a mix of automatic shut-off and remote controlled valves) in the San Francisco Peninsula in 2011. Approximately 200 additional valves are proposed by PG&E to the CPUC to be replaced, automated, and upgraded.

What's your timeline?
Upgrading major infrastructure is a major undertaking. We will be working with regulators and third-party experts to help determine scope and timing. However, we've already begun enhancing our inspections of gas transmission infrastructure. If we identify any threat to public safety, whether through a customer report or our own ongoing assessments, we address the situation immediately.

Earthquake Concerns

How safe are transmission lines with regards to an earthquake?
Gas transmission pipelines are generally resistant to earthquake damage and are expected to be operational following earthquakes.

In locations where there is believed to be a greater risk of pipeline failure from an earthquake, PG&E works to manage the risk of damage to the pipeline or replace the section of line with a design that is more earthquake resistant.

What does PG&E do if there is an earthquake? How do you know the line is still safe after an earthquake?
After earthquakes occur, PG&E immediately walks the system by foot and then conducts aerial assessments by helicopter a short time later.

Through our thorough assessments, we are able to confidently determine whether our facilities and pipelines have been damaged as a result of the earthquake.

Training and Collaboration with First Responder

Have the first responders in my city been trained to respond to gas leaks and gas emergencies?
PG&E works with external partners such as first responders and public safety officials to enhance training for emergency preparedness and response. Enhanced emergency prevention, preparedness and response programs consist of education programs for first responders, contractors, infrastructure departments, community members, school children, and other stakeholders.

PG&E has:

  • Increased educational and interactive session – including practice drills – with first responders to meet demand
  • Developed contact list for all local first responders (~1800) to facilitate future communication and notifications; will have the ability to track usage more accurately than with mailing to improve outreach over time
  • Launched PG&E first responder website portal
  • Conducted Joint CAISO/CPUC Gas Curtailment Exercise on 8/12/2011.
  • Provided maps, GIS data, and other information to first responders

PG&E has these additional activities planned:

  • Incident Command System training (September)
  • First responder workshops (Q4 2011)
  • First responder online portal for training material downloads and for scheduling a PG&E representative to come to site and deliver training (Q1 2012)

In enhancing the prevention, preparedness and response program, PG&E will create a consistent, coordinated emergency response plan that incorporates learnings from prior experience and industry benchmarks. Additionally, a more coordinated plan will ensure that emergency response preparedness is embedded in PG&E's operations.

And, with the implementation of public safety education programs and enhanced outreach, PG&E expects to see fewer preventable incidents (such as dig-ins to gas and electric assets), a more informed and safer citizenry, improved coordination during emergencies, faster restoration times following an incident, and line-of-sight accountability for prevention, preparedness and response performance.

Class Location Report

Why did PG&E perform a system-wide gas pipeline class location study?
We are conducting top-to-bottom review of our gas operations to improve our performance and bring it to industry-leading levels. We initiated this review last fall following a CPUC request and have implemented a new procedure that calls for annual class reviews.

How are pipelines classified or rated?
Under federal and state regulations, the class designation of a pipeline is based on the types of buildings, population density, or level of human activity near the segment of pipeline, and is used to determine the pipeline's maximum allowable operating pressure ("MAOP").

Pipelines are rated Class 1 to Class 4, based on increasing level of population. Class 1 being the lowest population/consequence (10 residences or businesses per mile of pipeline), Class 3 and 4 being the highest (Class 3 is 46 or more homes or businesses per mile, and Class 4 is an urban area where buildings of four or more stories are prevalent).

What were the results of the system-wide study?
This review has indicated that some segments of pipe had or may have a maximum allowable operating pressure higher than appropriate for its current class location.

As a result, the company has identified 7.5 miles of pipeline – consisting of multiple shorter segments in different areas of PG&E's service territory – where it is necessary to reduce operating pressures. PG&E has already completed pressure reductions on approximately 3.5 miles of pipelines. Work to lower the pressure on the other 4 miles is under way – an effort that involves over thirty different locations and requires careful planning to ensure safety and avoid unintended adverse consequences.

The company is still evaluating location data and assessing operating pressures for approximately 100 miles of pipeline in its system, and is working to complete that work as quickly as possible.

What is PG&E doing to ensure public safety related to the pipelines that have been reclassified?
Safety is PG&E's top priority. We are verifying that operating pressures on all of our lines are appropriate for their location. Where necessary, we are lowering the pressure.

In the weeks and months ahead, PG&E will work to prioritize the engineering work and field upgrades of these newly classified segments to bring them back up to the operating pressures needed to provide longer term reliability to its customers.

Pipeline Safety Enchancement

What is PG&E proposing to do to modernize its pipelines?
PG&E's plan proposes to replace over 180 miles of pipeline, strength test more than 780 miles, retrofit about 200 miles to accommodate in-line inspections, and in-line inspect over 200 miles.

If the CPUC decides to implement a different set of rules and regulations, will you still undertake the actions outlined in your proposal?
PG&E's Pipeline Safety Enhancement Plan was developed in response to the CPUC decision concerning new pipeline safety regulations. The Plan was developed with the intention of tougher, safer standards for pipeline safety. PG&E has and will continue to implement any new CPUC rules and regulations it adopts.

Why didn’t you take any of these steps before the CPUC required gas utilities to file an Implementation Plan?
The Commission ordered the California gas utilities to file implementation plans in June, 2011. Prior to that date PG&E had already begun taking many actions to address its gas transmission pipelines. These steps were all taken prior to the CPUC order and we are continuing this work today.

Does PG&E's plan encompass everything that PG&E is doing as a result of the San Bruno accident?
No. The Plan only represents part of PG&E's overall plan to enhance gas transmission safety and improve its overall gas operations by strength testing or replacing all pre-1970s pipe that do not have full documentation of a pressure test conducted to modern standards. In addition, the plan includes PG&E's proposal for installation of automatic shut-off valves, improvements in record-keeping, interim safety measures, and emergency response.

In addition to these efforts, PG&E has created a separate operating unit for our gas operations under the leadership of a newly hired gas operations expert who brings 30 years of experience in improving some of the nation's oldest gas systems. PG&E is also working to implement broad changes across the company to increase public safety.

How did PG&E arrive at this Plan? Does this plan include input from third parties such as regulators, industry experts, etc.?
The Pipeline Safety Enhancement Plan reflects new regulatory requirements which establish a known margin of safety across PG&Eamp;'s gas transmission system; incorporates lessons from the San Bruno accident, NTSB recommendations, Independent Review Panel findings, and industry benchmarking; and has been shared with/incorporates feedback from key regulators, industry experts, utilities and other interested parties.

What are the potential safety issues related to this work that customers and the community should be aware of?
The pressure testing and replacement work will be conducted in a manner that ensures the safety of the surrounding community. Our customer outreach plan is designed to inform customers when work is scheduled, what work PG&E is doing, and what to expect in terms of length of tests, impacts to service, or access restrictions. In certain limited cases, PG&E may have to close streets or ask customers to vacate their homes (if located in very close proximity to a pipeline) while a test is conducted. Our customer outreach efforts are designed to minimize inconvenience and provide clear information so customers and the community know what to expect.

How many valves is PG&E automating in Phase 1?
PG&E's plan proposes to automate 228 valves in Phase 1.

How many valves will you automate in the Bay Area?
Within Phase 1, approximately 60% of automation miles will be installed on pipelines located in the Bay Area (SF Peninsula, South East Bay and South Bay). In 2011 PG&E will automate 29 valves in the SF Peninsula

What are the benefits of automatic valves?
Among other things, installation of automated valves will result in quick shutoff off of gas and isolation of a pipeline segment if it ruptures, facilitate emergency response and reduce the potential threat and impact on the public and property, minimize property damage by eliminating the gas from a rupture in less time and allowing emergency responders to take action more quickly, and minimize the quantity of gas released during a pipeline rupture, reducing environmental impact and containing the loss of product.

What is the rate increase for customers?
A typical residential customer would see an average monthly gas bill increase of $1.93, from $45.23 to $47.16. A typical small business customer would see an average monthly bill increase of $14.96, from $279.80 to $294.75.


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