The largest gasoline spill in North Carolina history just got bigger.
Colonial Pipeline has released new figures, estimating at least 1.2 million gallons of gasoline spilled from a broken pipe in Huntersville last summer, more than 17 times the original figure. The new numbers are included in a 1,600-page Comprehensive Site Report filed with the NC Department of Environmental Quality yesterday.
In days following the Aug. 14, spill, Colonial estimated the amount at 63,000 gallons, but soon adjusted that figure to 272,000 gallons. In November, it increased that amount to 360,000. State regulators determined that the calculation still “significantly underestimated the volume of gasoline released.”
On Dec. 9, DEQ sent a letter to the company asking for more precise figures and other information, which was due Dec. 23. Colonial subsequently asked for, and received, an extension until this week.
The spill occurred in the Oehler Nature Preserve, and was discovered by two teenage boys riding ATVs in the area.
Colonial attributed the accident to a broken 42-year-old section of pipe. A preliminary analysis identified a through-wall crack as the source of the release, the company said today, although a final determination of the cause will be made once the technical analyses are complete.
As of Jan. 20, roughly 582,000 gallons of free product and 253,000 gallons of petroleum contact water have been recovered and transported off-site for disposal, according to DEQ.
“The size and scope of this spill requires a rigorous approach to oversight and remediation,” said Division of Waste Management Director Michael Scott in a press release. “We will do a thorough review of the information provided, as it is vital to determine the full extent of the impact in order to guide the cleanup and protection of public health and the environment. DEQ will continue to hold Colonial accountable and oversee their cleanup efforts.”
Colonial has installed 81 groundwater monitoring wells and 50 recovery wells to capture the gasoline, in and near the release location. None of the drinking water wells tested within 1,500 feet of the spill has detected petroleum products above laboratory reporting limits, the company said. But monitoring well data shows groundwater — the source of drinking water for private wells — is contaminated with roughly 20 chemicals, some of them known carcinogens. This includes benzene concentrations are 966 times the state’s maximum contaminant level. Concentrations of toluene exceed three times that level, and another type of hydrocarbon associated with petroleum products, C5-C8 Aliphatics measured 100 times higher than legally allowed.
As a precaution, the company has connected two households to the Charlotte public water system. In October and November, Colonial Pipeline bought three homes near the spill.
In a statement on the Colonial website, the company said it is “committed to protecting public safety, restoring the natural environment, and meeting or exceeding all regulatory requirements. We will continue to work with local partners to remediate Oehler Nature Preserve, and we will expand area partnerships as part of our ongoing Environmental Partners Program. We also remain committed to regaining the trust of our neighbors who have been affected by this event.”
Colonial has estimated it will incur costs of at least $10 million, including $2.6 million to clean up and monitor the contaminated groundwater and soil. DEQ has cited the company for environmental violations, but has yet to assess a penalty. The federal Pipeline & Hazardous Materials Safety Administration has not issued violations related to the spill.