Colonial Pipeline Spill Information - Huntersville, N.C.

Background

On Friday, August 14, 2020, at 5:42 p.m., local and state response agencies and Colonial Pipeline were notified of liquid product smelling of gasoline near the intersection of Huntersville-Concord Road and Asbury Chapel Road in the Oehler Nature Preserve. Local first responders and Colonial Pipeline employees responded to a leak in one of its underground lines crossing the Oehler Nature Preserve owned by Mecklenburg County, located at 14511 Huntersville-Concord Road east of the Town of Huntersville in Mecklenburg County. The pipeline was immediately shut down to conduct repair work. As of Wednesday, August 19, the repair to the pipeline has been completed. Cleanup efforts and remediation are underway, with oversight by the Division of Waste Management. 

Emergency Response

Emergency Response

The Department of Environmental Quality’s Division of Waste Management, along with Charlotte/Mecklenburg County Emergency Management, Town of Huntersville and Colonial Pipeline, have been responding to the situation since it began on August 14. 

To address the emergency nature of the situation, Colonial Pipeline began soil excavation to reach the underground pipe. Foam was used to limit flammable vapors. As of Sept. 15, 2020, no product was detected in nearby surface waters, and surface waters continue to be monitored. Soil and water supply well samples were collected during initial response efforts. Colonial Pipeline established a perimeter of 2,000-feet from the breach for environmental sampling purposes. As many as 22 drinking water wells have been tested for petroleum products; to date, those samples have not shown any gasoline products in the results. The first two rounds of supply well sampling were wells within a 2,000-feet radius; and the second two rounds were within a 1,500-foot radius. More than 80 soil samples have been collected with only those nearest to the leak showing impacts from gasoline products. Thirty-two product recovery wells and 47 groundwater monitoring wells have been installed. As of Nov. 30, 2020, Colonial Pipeline estimates that 354,060 gallons (or 8,430 barrels) of gasoline was released from the fuel line.

Colonial Pipeline has reported the cause of the release as equipment failure. The full extent of the environmental impacts from the spill is currently being assessed and necessary proactive actions are being undertaken to ensure that these impacts are minimized. Local, state and federal agencies are working in cooperation with Mecklenburg County agencies, the Town of Huntersville and its first responders, along with Colonial Pipeline, on initial cleanup activities.

Initial required response efforts

Initial required response efforts

NCDEQ has a process for site cleanup, which includes required sampling/testing and monitoring based on the evaluation of environmental impacts. The Department’s oversight adheres to regulatory requirements. NCDEQ has sent Colonial Pipeline a Notice of Regulatory Requirements (NORR) that outlines the requirements that Colonial Pipeline must meet during the initial phase (described above) of site cleanup.

The immediate response –  called the Initial Abatement Phase – requires Colonial Pipeline to stop the leak and address impacted soils at the point of release. As part of this phase, the responsible party (Colonial Pipeline) samples soil and groundwater at the release site and at drinking water supply wells and surface waters within an area set by NCDEQ. Air monitoring is also on-going at the worksite but not required by DEQ’s non-underground storage tanks statutes. Colonial Pipeline is providing sampling and testing data to NCDEQ. There have been no gasoline impacts identified during the four rounds of sampling for water supply wells and surface waters as of Sept. 15, 2020.

Colonial Pipeline has 90 days to submit an Initial Assessment Report that documents all of the actions it has taken during the initial response phase, which includes all soil, groundwater and surface water data and documentation on amounts of soil removed from the site.

On Sept. 25, 2020, DEQ issued a Notice of Violation to Colonial Pipeline for impacts to groundwater quality.

On Dec. 9, 2020, DEQ sent Colonial Pipeline a second Notice of Regulatory Requirements for additional information needed to carry out DEQ's investigation into the nature of the release. 

On Feb. 24, 2021, DEQ issued a Notice of Continuing Violation to Colonial Pipeline for impacts to groundwater, indentifying actions needed to complete the required Comprehensive Site Assessment.

Next steps

Next steps

Following receipt of the Initial Assessment Report, NCDEQ will require a Comprehensive Site Assessment (CSA) that specifies that the groundwater plume and soil impacts be fully identified and described. DEQ must approve the CSA before Colonial Pipeline can prepare and submit its Corrective Action Plan, which is a plan that details Colonial Pipeline’s actions to clean up any remaining soils and groundwater to state groundwater standards.

Air Monitoring

Air Monitoring

The air monitoring at the Colonial site shows concentrations below CDC and NIOSH exposure guidelines.

In April 2021, the DEQ's Division of Air Quality (DAQ) and Mecklenburg Air Quality installed an ambient air sampler on-site to evaluate specific volatile air pollutants during clean-up efforts. This sampling site was established to screen for these compounds and help inform decisions about the need for long-term monitoring.

The sampler collects a 24-hour composite air sample every six days in a specially prepared and certified 6-liter canister. This canister sample is subsequently retrieved and returned to the DAQ central laboratory for analysis for the suite of compounds using EPA Compendium Method TO-15.

While there are not federal or state ambient air quality standards for this suite of compounds, there are exposure guidelines for many of the compounds established by the Centers for Disease Control and Prevention’s Agency for Toxic Substances and Disease Registry (ATSDR) and National Institute of Occupational Safety and Health (NIOSH) to which the monitoring data can be compared. Those guidelines provide human inhalation exposure limits to various compounds below which adverse health risks are not expected over a specified duration of exposure. More information on the exposure guidelines can be found on the ATSDR and NIOSH websites.

The table below gives the compound concentration averages for samples collected between April 4 and July 27, 2021. These values were all found to be below the ATSDR or NIOSH guidelines for which values are available.

Name

Huntersville Averages
              
(ppb)

1,1,1-Trichloroethane

Not Detected

1,1,2,2-Tetrachloroethane

Not Detected

1,1,2-Trichloroethane

0.055

1,1-Dichloroethane

Not Detected

1,1-Dichloroethene

0.032

1,2,3-Trimethylbenzene

0.077

1,2,4-Trichlorobenzene

0.184

1,2,4-Trimethylbenzene

0.044

1,2-Dibromoethane

Not Detected

1,2-Dichlorobenzene

0.004

1,2-Dichloroethane

0.005

1,2-Dichloropropane

0.023

1,3,5-Trimethyl Benzene

0.024

1,3-Butadiene

4.169

1,3-Dichlorobenzene

0.018

1,4-Dichlorobenzene

0.043

1,4-Dioxane

0.052

1-Bromopropane

0.418

1-Butanol

2.614

2-Pentanone

0.050

3-Hexanone

0.188

3-Pentanone

0.121

Acetaldehyde

1.872

Acetone

3.299

Acetonitrile

3.083

Acrolein

0.668

Benzene

0.353

Benzyl chloride

0.103

Bromodichloromethane

0.274

Bromoform

Not Detected

Bromomethane

Not Detected

Carbon disulfide

0.218

Carbon tetrachloride

0.019

Chlorobenzene

0.040

Chloroethane

0.130

Chloroform

Not Detected

Chloromethane

0.480

cis-1,3-Dichloropropene

Not Detected

Cyclohexane

0.578

Cyclopentane

2.642

Ethanol

Not Detected

Ethylbenzene

0.065

Freon 11

0.120

Freon 113

0.016

Freon 114

Not Detected

Freon 12

0.215

Freon 22

0.459

Hexanal

0.143

Hexane

1.365

Iodomethane

0.049

Isobutene

3.638

Isoprene

0.853

Isopropyl Alcohol

0.416

m,p-Xylene

0.142

Methacrolein

1.328

Methyl butyl ketone

0.085

Methyl ethyl ketone

0.581

Methyl isobutyl ketone

0.018

Methyl tertiary butyl ether

Not Detected

Methyl vinyl ketone

0.602

Methylene chloride

0.088

n-Butanal

2.272

n-Pentane

8.308

o-Xylene

0.064

Propanal

1.965

Propylene

0.465

Styrene

0.048

Tetrachloroethylene

0.060

Toluene

0.985

trans-1,2-Dichloroethene

0.097

trans-1,3-dichloropropene

0.100

Trichloroethylene

Not Detected

Vinyl acetate

1.657

Vinyl chloride

Not Detected

Correspondence

Correspondence

Correspondence

Data, Results and Required Reports

Data, Results and Required Reports

The NCDEQ guidelines for non-UST releases can be found at: https://deq.nc.gov/about/divisions/waste-management/ust/nonust-program.

Air Quality data can be found under the "Air Monitoring" tab located above.

Data, results and required reports: 

Regulatory Authority

Regulatory Authority

The Department of Environmental Quality’s Division of Waste Management houses the Underground Storage Tanks Section, which has regulatory authority for the cleanup of gasoline spills. The NCDEQ guidelines for non-UST releases can be found at: https://deq.nc.gov/about/divisions/waste-management/ust/nonust-program.

The U.S. Department of Transportation’s Pipeline and Hazardous Materials Safety Administration or PHMSA is the federal agency that regulates pipeline safety. More information can be found at: https://www.phmsa.dot.gov/.

Historical files

Historical files

The N.C. Department of Environmental Quality's Underground Storage Tanks Section does not regulate the operations of petroleum pipelines in the state. The regulatory authority for operational oversight for petroleum pipelines falls under the Public Utilities Commission. However, the Underground Storage Tanks Section does have regulations for when there are above-ground spills and releases of petroleum. The historical files below contain records of historical petroleum (gasoline) spills and releases by Colonial Pipeline in North Carolina.

Historical files of petroleum spills or releases by Colonial Pipeline as regulated by the N.C. Underground Storage Tanks Section.

If the above link does not bring you to the documents, they can be reached by going to the DWM Documents webpage,  

  • Click on Laserfiche WebLink (public interface, new document management system)
  • Click "Browse" in the upper left corner
  • The folder path is Underground Storage Tanks > Colonial Pipeline

Note: Colonial Pipeline's may also be regulated by DEQ's other regulatory divisions.  

Health-related Questions

Health-related Questions

If you have questions about health concerns from exposure to gasoline or gasoline products, contact the Mecklenburg County Health Department at (704) 336-4700.

Resources

Resources

Materials

Involved agencies