This is the second installment of a story on the Suncor oil spill. Read the first installment here.
A Little History, the Chronology of Events Leading up to the Spill & the Clean-Up Response
“These refinery assets are 1938 vintage,” says John Gallagher, vice president of refining for Suncor Energy. “It is important to note that Suncor purchased Plants 1 and 3 from Conoco Phillips in 2003, and purchased Plant 2 from Valero in 2005. We can only speak to the refinery’s operations from the time we acquired these assets.”
At the Commerce City site, Suncor processes Canadian oil sands crude into refined petroleum product. That in turn produces gasoline, diesel fuel, and paving-grade asphalt. (The facility supplies between 35 and 40 percent of Colorado’s demand for gasoline, diesel and jet fuel combined, and 75 percent of Colorado’s demand for asphalt, according to the Colorado Department of Public Health & Environment (CDPHE).)
On a historical note, this is not the first spill to hit Sand Creek. There had been releases into the creek in the early 90s, says Warren Smith, community involvement manager in the Hazardous Materials Waste Management Division at the CDPHE, and a very small one from a burst pipe in August 2011. But this is the largest to leave the property in decades.
And that’s the main challenge with this spill, at least for the present: To keep it from leaving Suncor’s grounds and entering Sand Creek.
It all started, or at least was brought to the state’s attention, on November 27, 2011, when a carp fisherman noticed a black “goo” on the surface of the water.
EPA emergency response crews were called in and the clean-up was underway.
“When oil is potentially reaching rivers, jurisdiction falls to the EPA,” says Matthew Allen, public affairs officer for the EPA Region 8, explaining that Sand Creek joins the S. Platte River a short distance after it passes the Suncor property.
The EPA, with Suncor’s and CDPHE’s help and cooperation, removed all of the surface oil relatively quickly. They determined that the spill was from a seep, and stepped back to let the state handle it after the immediate and visible spill was addressed.
“A seep is something that follows the natural water table and it isn’t something that you can just pinpoint,” explains Allen. “It doesn’t mean that the work is done, it means it’s satisfactory enough to fall back to the state’s jurisdiction.”
The state had already been keeping tabs on the progress at Suncor based on prior clean-up orders. Here is a recent chronology of events, compiled by the CDPHE:
February 2011: Suncor discovered LNAPL (liquid hydrocarbons floating on groundwater) in a couple of areas onsite at the refinery. Shortly thereafter, the source was determined to be a leaking underground pipe inside refinery boundaries.
October 2011: State issued a Notice of Additional Work to investigate the extent of contamination and remediate. (Suncor was already implementing extensive clean-up under a 2007 Corrective Action Order).
November 2011: Liquid hydrocarbons were discovered seeping into Sand Creek and at the same time the adjacent property owner, Metro Waste Water, discovered hydrocarbon vapor in one building.
December 1, 2011: State issued an Interim Measure Order to: stop the seep and clean up any visual impacts; begin surface water sampling (BTEX sampling results listed below) along the length of the creek and a stretch of the South Platte River; sample indoor air in all buildings on Metro’s property and mitigate if necessary; and investigate groundwater contamination on Metro’s property.
December 30, 2011: State issued another Interim Measure Order to: sparge (aerate) the creek water; install a full scale LNAPL recovery system along the length of the creek to ensure LNAPL wouldn’t impact the creek in the future; stop using tap water at the refinery and sample all taps; sample tap water on Metro’s property; investigate the refinery’s water distribution system to ensure that surrounding water supplies hadn’t been impacted.
January 23, 2012: State issued a third Interim Measure Order to: investigate the southwest corner of the refinery property; sample air in offsite buildings and mitigate if necessary; sample tap water on adjacent property; evaluate options in case contamination was migrating offsite into Burlington Ditch.
According to Smith, it is correct to say that the seep of “liquid” hydrocarbons stopped in December, though there is still some in various places 10 feet underground floating on the ground water table. To combat this issue, Suncor has installed underground walls, called “hanging slurry walls,” to intercept it and return it to the refinery for processing.
The part that still remains an issue, and a thorny one at that, is the dissolved hydrocarbons.
“Unfortunately, as the liquid hydrocarbon floats on the groundwater, a small percentage of it dissolves,” explains Smith. “The hydrocarbons dissolved in the groundwater are a challenging technical issue; they are the same material as the liquid hydrocarbons. Benzene, ethyl benzene, toluene and xylenes (BTEX) are four easily measurable chemicals found in this dissolved material, and these four compounds are the primary components of gasoline. There are many other complex chemicals in gasoline, but these are the “markers” that we track to identify the presence and severity of the contamination.”
In addition to the hanging slurry walls, Suncor is being required to sparge, or aerate, the groundwater that contains the dissolved hydrocarbons. This process blows air into the ground through wells, pumping up the dissolved hydrocarbons as a vapor, which is then captured and run through a gasoline engine to burn it off.
The Denver Post has reported extensively on benzene levels (BTEX sampling results listed below), some of which remain at 400 parts per billion (ppb) or higher in the South Platte and at monitoring wells along Sand Creek. This is substantially higher than the national drinking standard, which is 5 ppb (this is a slightly misleading statistic, however, for multiple reasons; more on this in the next installment), but lower than the Aquatic Life Warm Water standard which is 5,300 ppb. Regardless of levels, Suncor does not have a permit to release anything into Sand Creek.
The question now is whether the measures put in place will stop the dissolved hydrocarbons from entering the creek water.
“These systems have only recently started up, and it will take a few months to evaluate their effectiveness,” says Smith.
As far as pinpointing the exact location of the seep, Smith thinks they have found the culprit.
“We believe the source was a dead-end spur that they didn’t even really know was there and it leaked from that spur and then was able to migrate off-site.”
Next week’s installment will look at the potential health impacts on the surrounding area, including people, wildlife, and the environment.
Map of the Spill Area
Benzene, Toluene, Ethylbenzene & Xylenes (BTEX) Levels in Sand Creek & the S. Platte (provided by CDPHE)
- Initial Sand Creek and S. Platte Surface Water BTEX Results
- Analytical Report 280-28589-1
- Analytical Report 280-28868-1
How to Read the Water Sampling Data
The spreadsheet tracks concentrations of Benzene, Ethyl benzene, Toluene and Xylenes (chemicals found in gasoline and similar hydrocarbons) in Sand Creek and the South Platte River.
Here are some tips to help you interpret the chart:
- SCSW means Sand Creek Surface Water, so SCSW-07 means Sand Creek Surface Water monitoring location No. 7.
- SPRSW means South Platte River Surface Water.
- BDSW means Burlington Ditch Surface Water.
- The numbers in the vertical columns represent parts per billion.
- Boldface numbers indicate a reading in excess of water quality standards.
- The SCSANDBAR reading represents a grab sample at the seep location taken by EPA’s emergency response team on the first day of their response. The seep was stopped in early December, so further samples at that site were unnecessary.
- Note that sampling has been discontinued at some locations, but that the chart shows all the samples taken to date.
- Don’t overlook the other books attached to the spreadsheet (see the tabs at the bottom of the page). The Benzene Graphs tab has graphs that show the actual readings and the trend over time for benzene concentrations at different sampling locations. The individual readings fluctuate, but the trend is what is most important.