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 covering Michigan’s recent incident history. Frequent readers might remember that last month, Michigan appeared as one of the eight states to have at least three more incidents in 2022 than in 2021. Despite this, Michigan has a considerably below-average rate of incidence. Since 2010, “The Mitten State” has averaged about four incidents every 100,000 miles, compared to the national average of 7.6 incidents per 100,000 miles of pipeline.
From 2010 to 2022, Michigan pipelines caused:
- 219 total incidents, including:
- 56 Hazardous Liquid incidents
- 68 Gas Transmission incidents
- 95 Gas Distribution incidents
- 124 significant incidents
- 24 incidents ending in injury and/or fatality causing:
- 33 hospitalized injuries
- 12 deaths
- 64 incidents resulting in fire and/or explosion
- 3,707 total members of the public were evacuated
- Incidents have released:
- 1,391,458 gallons of hazardous liquids
- 1,514,581 thousand cubic feet (mscf) of gas
In general, Michigan’s incident rate is lower than the national average but slightly higher than the average of its neighbors – listed as “Adjacent” in Plot 1. This remains true when only looking at significant incidents (Plot 2), although the state did see a bit more volatility, given spikes in 2014 and 2015.
When breaking out Michigan’s incident rate by pipeline system, it becomes apparent that Michigan’s natural gas pipelines track very closely to the national average. Michigan’s differences lie in the hazardous liquids pipeline network in the state. In the period studied, Michigan’s liquid pipelines presented a more volatile trend than gas. After a shaky early 2010s, liquids pipelines performed better than the national average for hazardous liquid incident rates before facing considerable setbacks in 2021.
Similar to states like Tennessee, the highest-cost incident was a liquid spill, as presented in Plot 4. Although six of the 10 most expensive spills were on gas transmission lines, the Kalamazoo Oil Spill was responsible for over a billion dollars in damages. This total far eclipses the cost of other incidents in Michigan.
Of the 103 unique pipeline operator IDs in Michigan, 23 have been responsible for at least one incident since 2010. Eleven of these 23 operate integrity management programs under a different primary operator. For example, Great Lakes Gas Transmission Limited Partnership operates integrity management under TransCanada, suggesting that TransCanada is their primary operator.
The table below presents the three operators with the most incidents for each system in the state of Michigan over the 2010 – 2022 period. The trend column displays their annual incident rate from 2010 to 2022, 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 Michigan – 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|
|19 Others (HL, avg.)||0.8||23%||22.95||2,614||646||25,751||9,085|
|SEMCO ENERGY GAS COMPANY||6.0||100%||0.59||1,951||325||12,100||2,017|
|11 Others (GD, avg.)||0.1||0%||0.48||9||9||161||161|
|53 Others (GT, avg.)||0.1||6%||5.02||214||135||450||202|
To offer a holistic view of the relative responsibility of operators in Michigan, this table can be referenced in conjunction with Plot 5, which looks at each operator’s incident causes. One trend that sticks out is how some of the larger operators – such as Enbridge and TransCanada – are seeing incidents due to equipment failure at a higher rate than average. For context, about 36% of all incidents nationwide are due to equipment failure. Nationwide, 17% of incidents are due to corrosion; in Michigan, only Energy Transfer eclipses that average at 42.9%. Finally, nationwide about 8% of incidents are due to other outside force damage, far lower than Semco’s 66.7%.
Plot 6 sheds some more light on 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 per unit. The third-largest relative incident in the state was the aforementioned Kalamazoo Oil Spill, occurring on July 25, 2010, on Enbridge’s Line 6B. This spill released 843,444 gallons of oil and was caused by a material failure of pipe or weld related to environmental cracking, according to Enbridge’s report. While this incident was third-largest relative release, it was the highest-cost incident. Other labeled incidents include those more than twice the average release size for their systems and those which were deemed serious per PHMSA’s definition. Serious incidents are those which require hospitalization of an injury or result in a fatality.
Consumers energy appears in this plot frequently, for the two largest gas releases and several serious incidents on transmission and distribution lines, respectively. The two high-release incidents, in particular, occurred on pipes installed in the 1950s. The 2017 incident specifically was due to a “material failure of pipe or weld” and per the incident narrative in the PHMSA data, caused a fire that ignited several trailers. The three Consumers distribution incidents in the lower left part of the plot caused five fatalities, three hospitalizations, and 700 people to evacuate in Wayne, Royal Oak, and Clio, MI. These incidents account for nearly half of Michigan’s 12 pipeline-related deaths during this period.