PST’s Data and GIS Analyst James Eager walks us through one state’s pipeline safety track record each month. Click on the “State of Safety” tag at the bottom of the post to see all of James’s entries to date.
This month, we are examining North Carolina’s incidence characteristics. From 2021 to 2022, North Carolina had the largest increase in incidents: from four in 2021 to 13 in 2022 (Plot 1). In this post, we will dig a bit further into their incident history leading up to this point. Mileage data for 2022 has not been released yet; any data covering incident rates presented here will include incidents up to the end of 2021.
From 2010 to 2022, North Carolina pipelines caused:
- 70 total incidents, including:
- 24 Hazardous Liquid incidents
- 22 Gas Transmission incidents
- 24 Gas Distribution incidents
- 47 significant incidents
- 5 incidents ending in injury and/or fatality causing:
- 9 hospitalized injuries
- 2 deaths
- 14 incidents resulting in fire and/or explosion
- 226 total members of the public to be evacuated
- Incidents have released:
- 2,055,787 gallons of hazardous liquids
- 118,152 thousand cubic feet (mscf) of gas
In general, North Carolina’s incident rate is less than half that of the national average, except for a brief spike in 2019 and 2020. This is also considerably lower than its neighboring states, which present a more volatile but consistently higher incident rate than the national average (Plot 2). Narrowing the scope of analysis to just significant incidents in Plot 3 shows that, despite a bit more volatility, this trend holds for these more impactful incidents as well.
In keeping with trends noted in previous State of Safety posts, the highest cost incidents in North Carolina tended to be on hazardous liquid lines. Three of the five highest-cost incidents were on these lines, including the highest-cost incident, which caused over $112 million in damages and released nearly 2 million gallons of gasoline in Huntersville, NC – north of Charlotte.
Of the 38 unique operators in North Carolina, eight have been responsible for at least one incident. Some familiar names operate in the state, including Kinder Morgan, Colonial, and Enbridge. In some cases, these operators appear on incident reports as their subsidiaries. For example, Kinder Morgan appears as Plantation Pipeline Company, a subsidiary of theirs that runs a large pipeline through the southeast.
The table below presents the three or four operators with the most incidents for each system in North Carolina over the 2010 – 2021 period. The trend column displays their annual incident rate from 2010 to 2021, with a green point at their maximum and an orange point at their minimum. The row labeled “Other” is an average of the other parent operators for each given system in North Carolina – including those without any incidents during this period. Significant incidents are presented as a percent of total incidents, and incident rates are given as incidents per 1,000 miles. Finally, releases are reported in thousand standard cubic feet (mscf) for gas incidents and gallons (Gal.) for hazardous liquids.
|Parent Operator||Total||Percent Significant||per 1K Miles||Trend||Total||per Incident||Total||per Incident|
|COLONIAL PIPELINE CO||21.0||52%||29.73||130,995||6,238||2,036,114||96,958|
|4 Others (HL, avg.)||0.0||0%||0.00||0||0||0||0|
|PUBLIC SERVICE CO OF NORTH CAROLINA (GD)||12.0||75%||0.61||39,132||3,261||12,426||1,035|
|PIEDMONT NATURAL GAS CO INC (GD)||11.0||73%||0.39||2,001||182||12,625||1,148|
|MONROE NATURAL GAS DEPT, CITY OF||1.0||100%||1.58||124||124||4,266||4,266|
|12 Others (GD, avg.)||0.0||0%||0.00||0||0||0||0|
|PIEDMONT NATURAL GAS CO INC (GT)||16.0||88%||6.13||13,067||817||72,561||4,535|
|PUBLIC SERVICE CO OF NORTH CAROLINA (GT)||2.0||100%||3.33||1,330||665||10,631||5,316|
|PITT LANDFILL GAS, LLC||1.0||0%||400.00||30||30||399||399|
|16 Others (GT, avg.)||0.0||0%||0.00||0||0||0||0|
To offer a more complete view of operator responsibility and safety in North Carolina, the table can be compared to Plot 5, which examines the causes of incidents for selected operators. Equipment failure and excavation damage appear the most common leading causes of incidents among operators, and in North Carolina, 43 of the 70 incidents reported were due to these causes. Excavation damage was the leading cause for both Piedmont Natural Gas and Public Service Co of North Carolina’s incidents, two of the three most incident-prone operators in the state. The third of those operators, Colonial, saw most of their incidents caused by equipment failure by comparison.
Finally, Plot 6 examines which operators are responsible for some of the state’s worst incidents during this period. Using a grouped z-score of incident releases, we can identify which release sizes were well above average in the state during this period – as a z-score of 0 denotes the mean release size. The largest spill relative to its system was the Piedmont Natural Gas Incident in Council, NC: an excavation damage incident that saw nearly 26,000 mscf of methane released. The exceptionally costly Huntersville Colonial Spill mentioned previously is also labeled on this chart. Finally, the third labeled incident is a Public Service Co incident caused by excavation damage to a distribution line which resulted in two fatalities and five hospitalized injuries.