PST’s Data Manager 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.
Quick Facts
From 2010 to 2022, South Dakotan pipelines caused:
- 22 total incidents, including:
- 14 Hazardous Liquid incidents
- 2 Gas Transmission incidents
- 6 Gas Distribution incidents
- 11 significant incidents
- 1 incident ending in injury and/or fatality causing:
- 1 hospitalized injury
- 5 incidents resulting in fire and/or explosion
- 19 total members of the public were evacuated
- Incidents have released:
- 316,557 gallons of hazardous liquids
- 41,611 thousand cubic feet (mscf) of gas
Incident Breakdown
In general, South Dakota’s incident rate tracks quite closely with its neighbors (“Adjacent”) and the rest of the country (Plot 1). Not only is it pretty similar to other geographies, it also lacks the same level of volatility often seen in states with fewer incidents than average. While the plot of significant incidents (Plot 2) shows a bit more volatility, it’s largely due to years where South Dakota had no significant incidents.
Similar to states like Tennessee and Michigan, the highest-cost incident was a liquid spill, as presented in Plot 3. In fact, four of the five highest-cost spills were on liquids lines. The top two were both crude oil spills on TransCanada lines, the largest was a rupture on the Keystone line in Amherst, SD on November 16, 2017. The total cost of the damage incurred was just under $50 million in current dollars.
Operator Analysis
Of the 25 unique pipeline operator IDs in South Dakota, nine have been responsible for at least one incident since 2010. Two of these 25 operate integrity management programs under a different primary operator. For example, Northern Border Pipeline Company 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 South Dakota 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 South Dakota – 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.
Incidents |
Cost (K, USD) |
Releases |
||||||
|---|---|---|---|---|---|---|---|---|
| Parent Operator | Total | Percent Significant | per 1K Miles | Trend | Total | per Incident | Total | per Incident |
| Hazardous Liquids | ||||||||
| NUSTAR | 5 | 20% | 16.08 | 412 | 82 | 21,231 | 4,246 | |
| TRANSCANADA (HL) | 4 | 75% | 18.17 | 60,104 | 15,026 | 293,769 | 73,442 | |
| MAGELLAN | 3 | 33% | 18.82 | 347 | 116 | 1,457 | 486 | |
| ENERGY TRANSFER | 2 | 0% | 7.27 | 10 | 5 | 101 | 50 | |
| 3 Others (HL, avg.) | 0 | 0% | 0.00 | 0 | 0 | 0 | 0 | |
| Gas Distribution | ||||||||
| MONTANADAKOTA UTILITIES | 4 | 75% | 1.76 | 644 | 161 | 205 | 51 | |
| MIDAMERICAN ENERGY COMPANY | 1 | 100% | 0.36 | 370 | 370 | 11 | 11 | |
| NORTHWESTERN ENERGY LLC | 1 | 100% | 0.43 | 120 | 120 | 5 | 5 | |
| 5 Others (GD, avg.) | 0 | 0% | 0.00 | 0 | 0 | 0 | 0 | |
| Gas Transmission | ||||||||
| NORTHERN NATURAL GAS CO | 1 | 0% | 1.26 | 30 | 30 | 5,200 | 5,200 | |
| TRANSCANADA (GT) | 1 | 100% | 5.48 | 124 | 124 | 36,190 | 36,190 | |
| 8 Others (GT, avg.) | 0 | 0% | 0.00 | 0 | 0 | 0 | 0 | |
To offer a holistic view of the relative responsibility of operators in South Dakota, this table can be referenced in conjunction with Plot 4, which looks at each operator’s incident causes. One interesting note that jumped out is that one of the largest operators in the state, TransCanada, sees all of its failures caused by equipment and materials. While this only may account for five total incidents, it does draw concern, as those causes are more under operator control than others. Nationwide, 10% of incidents are due to excavations and 8% due to other outside force damage; for MontanaDakota, half of its incidents are due to excavation and the other half to other outside force damage.
Plot 5 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 largest relative incident in the state was the aforementioned Keystone Rupture. This spill released 276,000 gallons of oil and was caused by a fatigue crack per NTSB’s report. 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.
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