Tag Archives: natural gas

Root Cause Analysis - Incident Investigation

Natural Gas Explosion Kills One in Kansas City

By ThinkReliability Staff

A natural gas leak at a business plaza in Kansas City was reported to the Fire Department just prior to 5 pm on February 19, 2013.  However, the area was not evacuated until just prior to an explosion that left 1 dead and 15 injured.  The leaking gas was not shut off until 3 hours after the report.

The causes that resulted in this tragedy can be examined within a Cause Map, or visual root cause analysis.  The analysis begins by determining which goals were impacted in a problem outline, which captures the what, when and where of the incident, as well as the impact to the goals.  In this case, the safety goal was impacted due to the fatality and injuries.  The environmental goal was impacted due to the natural gas leak and the customer service goal was impacted due to an ineffective evacuation.  (How do we know it was ineffective?  Because people were still present in a building that exploded due to a gas leak that was known for almost an hour, although the timing of the ordered evacuation is not known.)  Additionally, the property goal was impacted due to the destruction of restaurant, which was the site of the explosion, and damage to adjoining properties.  Lastly, the labor goal is impacted due to the investigation by state utility regulators, which is expected to take months of painstaking work to add detail to the causes which are already known.

Once these goals have been determined, we begin with an impacted goal and ask “Why” questions to add detail to the analysis.  The safety goal was impacted due to the death and injuries.  These occurred because of the explosion AND because people were in the proximity of the explosion.  Had the explosion occurred after a complete evacuation, the injuries would have been substantially reduced, if not completely prevented, although the property goals would have still been impacted.

An evacuation ws not ordered by the fire department, who deferred to the utility company.  The utility company was slow in determining that an evacuation was needed.  There was general confusion about the responsibility for determining an evacuation.   Per the city’s emergency response plan, the Incident Commander is responsible for evacuations.  However, no Incident Commander  was named on-scene until after the explosion, as it was determined that no incident yet existed.  Because quite a bit of flexibility is generally needed in determining whether an evacuation is needed (as an evacuation itself can be dangerous), the emergency response plan is necessary somewhat confusing (in this case, contained in a 90-page document).

The explosion itself resulted from an unknown heat source within the restaurant igniting leaked natural gas.  The natural gas was leaking as a result of being struck by a boring machine being used to install fiber-optic cable in the area.  It was later determined that the contractor did not have the necessary permit for the work, though it’s not clear if that led to confusion on the location of the gas lines, or if they were mislabeled, or if it’s just that it’s really difficult to see lines when digging deep trenches using a boring machine.

The extent and probability of an explosion is related to the volume of gas released during a leak.  Had the gas been turned off earlier, the explosion might have been avoided, or lessened, reducing the impacts to all the goals.  The gas was not turned off before the explosion, and after the explosion continuing fires made the shut-off locations difficult to reach.  it’s not clear why the gas wasn’t turned off immediately, though the choice to do so  does result in other impacts, such as the loss of gas to other customers.  In cases where the true extent of the issue is not known, it is difficult to make these decisions and limit potential effects.

Because one of the issues was not knowing the extent of the leak, it has been suggested that all fire department trucks be equipped with natural gas sniffers.    Additionally, an update to the city’s evacuation protocol has been called for that would, among other changes, give authority to the first arriving public safety official  to order an evacuation, resulting some of the confusion that led to the tragedy in Kansas City.

As this example shows, it’s not only attempting to prevent these events that’s important but also ensuring that emergency plans and protocol clearly define actions to be taken as well as responsible parties.  Drills and simulations can ensure that the plans and protocols are even more effective.   This is true not only for cities and fire departments but for any organization tasked with the safety of people . . . which is to say, all of them.

To view the Outline, Timeline, Cause Map, and Solutions, please click “Download PDF” above.

Root Cause Analysis - Incident Investigation

School Leveled by Gas Explosion

By Kim Smiley

On March 18, 1937, the London School of New London, Texas was leveled by a huge explosion.  Unfortunately, many people were in the school on the afternoon of the explosion and an estimated 280 students, 15 teachers, 2 visitors and a school secretary were killed.  This tragedy remains the worst catastrophe to occur inside a school in American history.

The cause of this tragic incident can be investigated by building a Cause Map, a visual root cause analysis, which shows the cause and effect relationships between the different factors that contributed to the explosion.  A Cause Map begins by determining which goals were impacted and in this example the safety goal is the obvious focus.  Causes are then added to the Cause Map by asking “why” questions to add additional information.  In this example, the safety goal was impacted by the large number of fatalities.  The deaths occurred because the school was occupied and the school was destroyed.

The school was destroyed because there was a large natural gas explosion.  The explosion occurred because there was a large quantity of natural gas in the school and a shop teacher turned on a sander and created a spark.  The gas was in the school because there was a leak, there was a large quantity of gas was trapped in a void space under the school and the gas leak wasn’t detected.  The investigation into this incident was never able to decisively determine what caused the natural gas leak.  The void space was under the school because the school was built on a slope.  The leak wasn’t detected because the school was using untreated natural gas which is both invisible and odorless.

Why was the school using untreated natural gas?  The school was trying to save money by eliminating their heating bill.  The school was located near oil fields and had tapped into a nearby residue gas line to provide heat, saving approximately $300 dollars a month.  Using free untreated natural gas was a common practice in the region.  The gas company turned a blind eye since natural gas was considered a waste product of oil drilling that was just flared off.

The end result of using free, but untreated natural gas was that no one could detect that the school was filled with natural gas.  One spark and the whole school was destroyed along with many, many lives.

As a result of this horrendous accident, all natural gas in the United States is treated to have an odor, usually with mercaptan which smells like rotten eggs, so that leaks can be detected by smell.

Root Cause Analysis - Incident Investigation

The Side Effects of Fracking: Explosive Water?

By ThinkReliability Staff

America’s push for clean energy has certainly been a source of intense debate – the safety of off-shore drilling, the hidden costs of ethanol subsidies, even the aesthetics of wind farms.  New evidence is set to increase the intensity on yet another topic – the debate over hydraulic fracturing.

Hydraulic fracturing is a process where internal fluid pressure is used to extend cracks, or fractures, into a rock formation.  It can occur in nature, but in man-made operations fractures are made deep in the earth by pumping fluid (mostly water) and a proppant (such as sand) out the bottom of a well.  The proppant prevents the fracture from closing back up after the injection of fluid stops.  Chemicals are sometimes added to the pumping fluid to aid in the process.  These fractures allow the gas or liquid trapped in the rock formation to flow back through the fracture, up the well and out for production.

More commonly known as “fracking”, the technique is used to release natural gas from shale rock formations.  These formations, especially common on the East Coast and in Canada, have provided thousands of new, well-paying jobs.  Fracking has allowed natural gas companies to access enormous reserves of natural gas, previously thought inaccessible and prohibitively expensive to drill.  In fact fracking has allowed drillers to tap what is potentially the world’s largest known reserve of natural gas in the Marcellus and Utica shale deposits, stretching from New York to Georgia.

As with any new technology however, there are potential consequences.  Lawmakers and regulators have debated the safety of the largely unregulated fracking industry, but with little definitive evidence either way…until now.  A study by Duke University has concluded that fracking does indeed lead to methane contamination in drinking water.  Methane is the primary component in natural gas and is not lethal to consume.  However, high concentrations are explosive.

The study determined that fracking causes methane to leak into drinking water.  Water sources within a kilometer were found to have significant levels of methane, more than 17 times higher than wells located further from drilling sites.  Furthermore, it was determined that the source of the methane was the much older methane released from the bedrock, versus newer methane produced naturally in the environment.

The exact reason for this is unclear, but a Cause Map can lay out the possible areas needing further investigation.  For instance, the frack chemicals might enter the water supply accidentally during the drilling process.  Spills could also contaminate surface water, or chemicals could migrate into the water supply.

The study indicates that chemical migration is most likely what’s happening.  Surface spills, which have happened, are not a major contributor to the wide-spread methane contamination; so that cause can be left in the Cause Map but won’t be investigated further for our purposes.  Furthermore, the study produced no evidence that the drilling process itself was causing the contamination; so that block can be crossed off the Cause Map.

That leaves one possibility – migration.  The chemicals (including methane) could migrate in two different ways – through the well casing or through the bedrock.  The study’s authors felt it was unlikely that chemicals were migrating thousands of feet through bedrock, so migration from well casings experiencing high pressure flow  is more probable.  While more evidence is needed, it is possible that the well casings are weakened by the fracking process which pushes sand through the casings at high pressure.

An EPA study looks to definitively determine fracking’s impact on drinking water, and specifically human health.  However that study is not scheduled to be completed until 2014.  Until then, lawsuits and tighter regulations are likely to dominate headlines.

Root Cause Analysis - Incident Investigation

Residential Natural Gas Explosion

By ThinkReliability Staff

The town of Allentown, Pennsylvania suffered severe physical and emotional damage on February 9, 2011, when 5 people were killed and 8 homes were completely destroyed.  The deaths and destruction were believed to be caused by a natural gas explosion, fueled by a 12″ gas main break.  In addition to the impacts to the safety and property goals, the natural gas leak, extended fire, and time/labor by 53 responders also impacted goals.

We can analyze the causes of these impacts to the goals with a visual root cause analysis.  Beginning with the impacts to the goals, we ask why questions to determine the causes that contributed to the incidents.  In this case, there was a delay in putting out the fire because the fire had a heat source from the explosion, a constant oxygen source (the environment) and a steady supply of fuel, as the natural gas continued to leak.  There was no shut-off valve to quickly stop the flow of gas.  It took the utility company 5 hours to finally turn off the gas.  It took 12 more  hours before the fire was completely put out.

The fuel for the explosion and the fire is believed (according to the utility company) to have come from a break discovered in the 12″ gas main.  A 4′ section of pipe, removed on February 14th, is being sent for a forensic analysis to aid in determining what may have contributed to the crack.  It’s possible there was prior damage – such as that from weather or prior excavations.  Most of the pipe in the area was installed in the 1950s, although some is believed to be from the 1920s.  Budget shortfalls have delayed replacing, or even inspecting the lines in the area, and officials have warned that continuing financial issues may continue to delay inspections and improvements,  causing concern with many residents, who suffered a similar natural gas pipeline explosion in 1994.

Because implementation of potential solutions to improve the state of the utility lines in the area may be limited by available funding, it’s unclear what will be done to attempt to reduce the risk of a similar incident in the future.   However, the unacceptability of resident casualties should stir some action so that this doesn’t happen again.