New estimates by Colonial Pipeline, responsible for the largest gasoline spill in North Carolina history, show that at least more gasoline escaped from a broken pipeline in Huntersville last summer. The company previous estimated 1.2 million gallons were released; a new estimate is still being calculated.
To illustrate the amount of gasoline that was spilled, the “Giant Peach” water tower in Gaffney, S.C., holds 1 million gallons of water.
An NC Department of Environmental Quality press release said that on April 15 Colonial verbally informed the agency that the previous estimate “was no longer accurate and that the model used was no longer appropriate.” DEQ said the news raised significant concerns about the accuracy of the estimated volume and the modeling it was based on.
“It is unacceptable that for eight months Colonial Pipeline has been unable to provide a reliable accounting of the amount of gasoline released into this community,” said DEQ Secretary Dionne Delli-Gatti. “We will take all necessary steps and exercise all available authority to hold Colonial Pipeline accountable for what has become one of the largest gasoline spills in the country.”
The revised estimate is based on new data from Colonial that the gasoline has penetrated more deeply into the soil than originally modeled. This is often referred to as a vertical plume. Previous spill estimates by the company did not account for these depths.
The company said it believes the deeper contamination can be removed.
A horizontal plume, the width of the contamination, appears to “remain contained to the general vicinity of the release,” according to the company.
“Each volume estimate that Colonial has provided since discovering the release has been based on the best available data at that time,” a Colonial Pipeline spokesperson said. “That said, while the estimated release volume likely will be revised as a result of this new data, we will continue to follow the science and communicate what we find with the public and our regulators. Our commitment to remediating this location and deploying the required resources to do so safely remains unwavering. We will be here for as long as it takes to safely remediate this area.”
No contaminants have been detected in the drinking water wells.
“We’ll follow the science and do everything to get this product,” the Colonial spokesperson said. “We’re committed to protecting the human health and the community, and we’re unwavering in our commitment.”
The spill occurred eight months ago, on Aug. 14, 2020, when a portion of the pipeline beneath the Oehler Nature Preserve broke. Colonial’s monitoring system did not detect the breach; it was discovered by two teenage boys riding ATVs in the preserve, which is in a residential area. It was the 32nd spill by Colonial in North Carolina since 2000.
Since then, Colonial has reported extensive groundwater contamination, but none in drinking water well samples within the sampling radius to date. Nonetheless, the company connected several homes that were on private drinking water wells to a public water supply. It also purchased three homes close to the spill. Colonial said it bought the houses to avoid inconveniencing the residents, because extensive clean up work and monitoring was occurring nearby.
The Huntersville spill could be representative of other weaknesses throughout Colonial’s 5,500-mile network, which spans from Texas through the Southeast and into New Jersey. The spill prompted federal the Pipeline Hazardous Materials and Safety Administration to investigate Colonial Pipeline operational and maintenance procedures; it concluded late last month that because of poor operational and maintenance procedures, the company’s entire pipeline could jeopardize public safety, property or the environment.
DEQ has cited Colonial with a Notice of Continuing Violation, which identified 22 deficiencies in the company’s comprehensive site assessment. The agency has also directed Colonial Pipeline to extend residential private well sampling radius an additional 500 feet, to 2,000 feet from the spill site.
Colonial is required to provide a revised comprehensive site assessment to DEQ by April 26.