By Glen Boatwright, Boatwright Consulting
Photos provided by the author
It’s 7:30 a.m. on a Friday. Your engine company has just been dispatched to a reported gas leak in a commercial area within the city. Upon arrival you observe a directional drill rig fully involved in fire and a high-pressure natural gas release which is also burning.
One worker with the directional drill crew has sustained serious second and third degree burns on his upper torso, face, and arms. Traffic is becoming gridlocked in the area. News crews have arrived on scene and are requesting information.
Pipeline incidents, while infrequent, can occur at any time and pose significant challenges for response and mitigation. When arriving at a reported pipeline emergency, it is critical to conduct a thorough scene size-up including identification of the product involved and the operator.
Also Read: How to Avoid Tunnel Vision on Routine Gas Calls
Pipelines transporting natural gas and highly volatile liquids are regulated by the U.S. Department of Transportation’s Pipeline and Hazardous Materials Safety Administration. Each pipeline must have signage that contains three vital pieces of information: the product being transported, the name of the operator, and a telephone number that is answered 24/7 by a live telecommunicator.
When conducting a scene size-up look for the telltale signs of a leak including:
- Hydrocarbon, rotten egg or sulfur odors in the area
- Roaring or hissing sounds
- Dirt being blown up into the air
- Visible vapor clouds
- Bubbles or oily sheens on waterways
- Fires at ground level
- Concentrated dead or dying vegetation
- Ice balls forming on pipe
- Excavation or construction equipment in the area
Once the operator has been identified and contacted, isolating the area, eliminating ignition sources, and investigating product migration should be tactical priorities.
Natural Gas Distribution Operations
There are more than 2.6 million miles of natural gas pipelines in the United States. Of that, 2.3 million miles are distribution pipelines. Product delivery by pipelines continues to be one of the safest modes of transportation in the United States. While safe, incidents involving natural gas distribution pipelines do occur.
With the proliferation of utility construction occurring across the country, damage to natural gas pipelines has been increasing.
Gas meters, which are owned by the utility, are the point of transition between delivery pipelines and the customer-owned service lines. They measure gas usage and provide over-pressurization protection.
Also Read: Preparing for Gas Releases and Hazmat Emergencies
Whether due to a house fire or carbon monoxide issue, firefighters may need to turn off the supply at the meter. Using the slot on a spanner wrench, the gas meter can be turned off at the lock wing with a quarter turn of the valve. Gas valves turned perpendicular to the pipe isolate the flow. Once a meter is valved off, leave it off. The natural gas utility will have to conduct a safety inspection and restore service, if appropriate.
In rare cases, electrical grounding to a gas meter (which is against the electrical code) have been found. This can create an electrical shock hazard. Be aware of wiring that appears to be grounded to the gas piping.
In rural areas, sometimes farm taps are installed to provide service to an individual customer where service from a distribution system is not available. Farm taps are small regulator stations that are attached to high pressure transmission pipelines or mains and reduce natural gas pressure to serve the customer.
Unfortunately, since farm taps are often installed adjacent to roadways, they are at risk from damage by vehicles and mowing operations. If responding to a damaged and leaking farm tap, isolate the area, eliminate ignition sources, and notify the pipeline operator.
Also Read: Colo. Hazmat Instructor Talks Hazmat Training
Above ground natural gas regulator stations reduce pressure from incoming supply delivered by high-pressure transmission or distribution mains. These stations are typically enclosed by fencing with signs that identify the operator, product, and an emergency contact telephone number. Sometimes, a regulator may be affected by debris in the pipeline resulting in a bypass to a relief device. This device safely vents the gas to the atmosphere avoiding a dangerous over-pressurization situation.
Depending on the pressure, the venting gas can be very loud, but the device is functioning as designed. If dispatched to a report of a natural gas leak at an above ground station and you observe a relief blowing, do not attempt to valve it off. This can create a dangerous over pressurization. Notify the operator, isolate the area, and allow the trained pipeline technician to remedy the situation upon arrival.
Response to a Natural Gas Pipeline Damage and Leak
Let’s go back to our Friday 7:30 a.m. scenario.
- What are the results of your scene size-up?
- What safety concerns exist?
- What are your response priorities?
- What additional resources are needed?
- What information would you want the natural gas utility to provide?
Not your routine gas call, is it? With all of the utility installation occurring nationwide-especially to support broadband access, this scenario could happen anywhere, anytime. So, in this case, the gas has ignited, which is a good thing.
Be mindful, however, that pipelines damaged underground can result in leaks elsewhere in proximity to the original incident. So monitoring for gas migration is prudent.
Never attempt to extinguish a burning natural gas fire. Eliminate the fuel source and let the fire burn out. Protect exposures but do not allow the excavation area to fill up with water, which will delay line isolation and repairs. Isolate the area and ensure that the pipeline operator has been notified.
A large percentage of natural gas distribution pipelines are plastic, which in most cases can be isolated using specially designed squeeze off tools. While some small-diameter steel distribution pipelines can be squeezed off (later requiring a cut out and replacement), most will require isolation by turning valves. This operation should only be conducted by trained and qualified utility personnel.
Pipeline operators are required by federal regulations to have on-going liaison with emergency responders. Take advantage of training and orientation sessions provided by your local natural gas utility personnel. Also, engage in scenario-based discussions that will enhance learning and preparedness for all participants.
