GAS IN MANHOLES, VAULTS, SEWERS
Gas in sewers can come from a number of sources,
including natural gas, propane, gasoline, sewage, and
electrical cable burnout. The utility company can
assist in identifying the type of gas involved and in
tracing its source.
Do not attempt to extinguish flames if gas becomes
ignited. Establish a hot zone around the opening,
and keep vehicles and bystanders away from nearby
manhole covers. Prohibit smoking and other potential
sources of ignition.
Do not open manhole covers to investigate without
consulting utility employees with specific expertise.
Opening a manhole cover with a smoldering fire
underneath can give similar results to opening the
front door of a building with an oxygen-starved fire
smoldering inside—presenting a backdraft situation.
Always test the atmosphere of a manhole, vault, or
sewer, first for oxygen levels and then for flammable
gases, carbon monoxide, and hydrogen sulfide.
Firefighters should not enter manholes, vaults, or sewers—leave that to utility personnel specifically trained
to do so. In no case should anyone be allowed to
enter a manhole if dangerous concentrations of gases
or vapors are known or suspected and, if personnel
enter, they must follow specific confined space entry
procedures. At underground gas events, do not work
or park over manhole covers/openings.
Check the basements of adjoining buildings for any
evidence of gas intrusion. If found, ventilate by opening windows and doors. Shut off open flame devices,
and do not operate electrical switches. If natural gas is
involved, handle as suggested in the section on escaping gas in buildings.
When fire personnel must enter manholes, vaults,
or sewers for rescue operations, follow confined space
EQUIPPED AND TRAINED
When under control, natural gas, like many other
hazardous materials, is harmless. Natural gas is widely
used for heating and air conditioning, water heating,
cooking, incineration, drying, power generation, and
many other commercial purposes in hotels, restaurants, schools, and many other occupancies. Natural
gas is also widely used for thousands of industrial
purposes every day. How we respond to emergencies involving this equipment can mean the difference between life and death for civilians as well as
emergency responders. Having access to meters that
are properly maintained/calibrated with personnel
properly trained in their use is critical, as is having
standard operating guidelines for response to gas
Ensuring prompt notification of the utility
company, isolating potential ignition sources,
metering the immediate area and other areas where
the gas could migrate, eliminating ignition sources
(the utility company may need to cut electric power
to the building for this), evacuating the area,
establishing a hot zone (both explosion and collapse),
ventilating the building as appropriate, and having
rapid intervention crews available will keep both
civilians and emergency responders safe. Contact your
local utility company to determine what training it
can provide on natural gas emergencies. Learning
should never stop.
Note: Further tactical advice can be found at www.
1. Davis, Mike, “Fatal Ewing gas explosion: PSE&G, contractor hit
with largest fines in state BPU history,” NJ.com, March 2015,
2. Focht, Brian, “How to Respond to Natural Gas Emergencies,”
FireRescue, September 2014, www.firerescuemagazine.com/
3. Griffaton, Grace, “More details emerge on deadly home explosion
in Manor Twp., Lancaster County,” Fox 43, July 2017, http://
4. Johnson, Riley, “Jeanne Jasa, victim of house explosion, dies,”
Lincoln Journal Star, August 2017, http://journalstar.com/news/
5. Uliano, Dick, “ATF locates disconnected vent pipe at scene of
deadly Silver Spring explosion,” WTOP, August 2017, http://wtop.
6. Walsh, Paul, Libor Jany, and Miguel Otárola, “Hours after gas
explosion at Minnehaha Academy, second body is found,” Star
Tribune, August 2017, www.startribune.com/minnehaha-academy-dead-missing-gas-explosion-minneapolis-critically-
Brian Focht, CFPS, CFEI, is deputy chief of the Willow Grove (PA)
Volunteer Fire Company and a senior training specialist with PECO,
assigned to gas training at the PECO Fire Academy. He was the
2016 Recipient of the IAFC Garry Briese Safety Performance Award.
Greg Jakubowski, a fire protection engineer and certified safety
professional, started his fire service career in 1978. He is a Pennsylvania state fire instructor and a former chief of the Lingohocken
(PA) Fire Company. Jakubowski is also a member of the IAFC and
a principal in Fire Planning Associates, a company dedicated to
helping fire departments, municipalities, and businesses with
To read more from Greg Jakubowski, visit www.firefighterna-tion.com/author/greg-jakubowski.