Red Butte Creek Oil Spill.

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DEQ Home > Locations > Red Butte Creek Oil Spill > HHRA FAQs  

Red Butte Creek Oil Spill: HHRA Press Release FAQs

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Is the Cleanup of the Creek Finished?

DWQ has not made a final determination if the cleanup was adequate. Both the human health and ecological risk assessments provide essential information for determining if the cleanup is complete. These assessments are both draft pending the outcome of the public comment period. In addition to the risk assessment results, other factors such as compliance with environmental regulations, effectiveness, feasibility, and cost are considered in determining the need for additional cleanup or other actions. Based on the existing monitoring results over the last two years and the preliminary results of the human health and ecological risk assessments, no additional remediation is anticipated. Samples taken after the cleanup was completed showed very low residues of petroleum hydrocarbons and polycyclic aromatic hydrocarbons (PAHs) in creek waters and sediment. These chemicals are related to crude oil from the spill or urban runoff. DWQ will continue to monitor additional samples to confirm that Red Butte remains safe. Regardless of the decision on the adequacy of the cleanup, Chevron continues to be liable for any additional spill oil discovered in the future.

What did the Human Health Risk Assessment Conclude?

The risk assessment found that the cleanup was successful and spill residues in Red Butte are similar to other Salt Lake creeks not affected by the spill. This conclusion is based on cancer risks from exposures to contaminants in the creek below or within the DEQ/USEPA risk management range, defined as an incremental cancer probability of one in one million to one in ten thousand. The majority of the health risks were attributable to chemicals called polycyclic aromatic hydrocarbons (PAHs). Other Salt Lake Creeks not affected by the spill including City, Emigration, Mill, and Parley's Creeks, have similar cancer risks. Non-cancer health effects (for instance, liver or kidney damage) are unlikely. Based on these conclusions, DEQ determined that Red Butte Creek is safe for regular use by local residents, including active children who play and/or dig in surface sediment at the bottom of the Creek. Additional monitoring is being considered to verify that the creek remains safe.

How Do You Know If Any Residual Oil Left in the Creek Poses a Risk to Human Health? Why Did You Do a Risk Assessment?

Once the active cleanup was complete, the creek was monitored for contamination every three months. Many additional samples were collected from specific areas where remaining contamination was suspected. We then conducted a human health risk assessment to determine if the cleanup was adequate to protect residents and other people who recreate in the creek.

Why Not Just Dig Up the Creek and Haul Away the Low-Level Contamination?

Additional remediation would cause additional adverse impacts to the creek and creek residents for little benefit and is not currently being considered. Digging up the creek would cause significant short-term adverse impacts to aquatic life in the creek and their food web due to the physical disturbance. Residents would have to tolerate noise, construction workers, and earth moving equipment during the removal. Many parts of the creek have difficult access resulting in serious technical challenges for any large-scale removal actions. A removal would have little long term benefit because contaminant concentrations in Red Butte Creek are already similar to other Salt Lake creeks. The removal of any additional contamination from Red Butte Creek that may have resulted from the oil spill would simply be replaced with ongoing contamination from urban runoff or other unidentified sources.

Is the Creek Safe For People? How About Pets?

Yes. The creek is safe for recreational use for people and pets. The water is safe for pets because no oil residues were detected in the water.

What are PAHs? How Can They Affect My Health?

Polycyclic aromatic hydrocarbons (PAHs) are a group of over 100 different chemicals that are formed by burning of coal, oil and gas, garbage, or other organic substances like tobacco or charbroiled meat. PAHs are also found in coal tar, crude oil, asphalt, creosote, and roofing tar. With so many potential sources, PAHs are common contaminants in the Salt Lake urban environment. The U.S. Department of Health and Human Services (DHHS) concludes that Americans are commonly exposed to PAHs unrelated to any spills or hazardous waste sites. The PAHs in Red Butte Creek likely come from a combination of the spilled crude and urban runoff. The PAHs are among the most persistent of the contaminants in crude oil and urban runoff and some PAHs are carcinogens. The estimated cancer risks from exposure to contaminants in Red Butte Creek or other Salt Lake Creeks are low and but most of the risk is from PAHs. Detailed information for PAHs and potential health effects is available in the ATSDR Toxicological Profile for PAHs.

What are Background Levels?

Background levels of chemicals are those that are normally found in the environment. There are two types of background levels: natural and human-caused. Natural background levels assume pristine conditions. Human-caused background levels are those that aren’t caused by a specific spill or release but are caused by a combination of human activities. Human-caused background for Red Butte Creek, specifically the concentrations of oil-related chemicals immediately prior to the spill, is unknown. Background levels are important because Chevron is only responsible for cleaning up its spilled oil. Potential sources of oil substances unrelated to the spill include roads paved with asphalt that contains oil, cars leak oil, and some contaminants found in our air can also be present in oil. While human-caused background is unknown, sampling other Salt Lake creeks not affected by the spill provides a way of estimating human-caused background for Red Butte Creek. The results of this comparison support that the cleanup was successful. Petroleum chemical residues in Red Butte are at, or very close to, human-caused background levels in other Salt Lake Creeks.

Is There Still Oil in Red Butte Creek?

Yes, residues likely attributable to the spilled oil are present. The cleanup removed spilled crude oil from the creek. Removing every drop of spilled crude is not feasible and residues were expected to remain. These spill residues will decrease with time because of several processes such as bacterial metabolism, breakdown from sunlight, and flushing by the flowing water. While the spill residues will completely decay with time, some of these same residues will continue to wash into Red Butte Creek from other sources during storms. This complicates determining which residues resulted from the spill and which are from urban background sources. A statistical comparison between residue concentrations in Red Butte Creek and other Salt Lake urban creeks could not detect significant differences. Based on this result and additional analyses of the data, DWQ concludes that remaining spill residues in Red Butte are very low or gone. Regardless of the source of the residues in Red Butte Creek, the residue concentrations are similar to those found in other creeks in Salt Lake. Additional monitoring is being considered to confirm these conclusions.

Why Are There PAHs in Other Salt Lake Creeks When They Didn't Experience an Oil Spill?

Samples collected from other urban creeks in the Salt Lake City area detected low levels of PAHs similar to concentrations currently found in Red Butte Creek. This shows that urban sources of PAHs, such as motor vehicles and urban runoff, are likely contributing to PAHs found in Red Butte Creek.

What Are the Health Effects From Exposure From the Oil Spill Before Chevron Performed its Clean Up?

In September 2011 the Utah Department of Health completed a Public Health Assessment which evaluated the potential health effects during and immediately following the spill. Residents living along the Creek were likely exposed to contaminants in the air during this time. Residents reported pervasive odors of oil and some residents reported feeling ill. No air monitoring data are available for these initial hours to evaluate the potential for health effects. However, the Public Health Assessment determined that once air monitoring started, the concentrations measured were unlikely to pose a health risk to residents, including children. The complete Public Health Assessment is available.

Did the Spill Contaminate Our Drinking Water?

No, Red Butte Creek is not used as a drinking water source for Salt Lake City. The spill is not expected to threaten the deep groundwater that is used for drinking water. This conclusion is based on how much oil was spilled, the short amount of time before the oil was cleaned up, and how oil behaves in the environment. In addition, there are protective layers of rock between Red Butte Creek and the drinking water aquifer. Salt Lake City continues to routinely monitor sources of our drinking water for contamination.

How Did the Spill Affect the Environment?

Two different approaches were used to estimate the environmental effects of the spill: counting insects and evaluating contaminant concentrations using the USEPA ecological risk assessment process. In small streams like Red Butte, insects are a critical component to the structure and function of the ecosystem that can be measured. The type and number of insects evaluates effects that have occurred especially when counts from un-impacted sites are available. The insect counts show that the crude oil and physical cleanup methods severely impacted the insect life of the creek. Follow-up sampling shows that the insect life is recovering. While the insect counts are useful for measuring effects that have occurred, the ecological risk assessment estimates the potential for long term future impacts The ecological risk assessment evaluated plants, insects, fish, mammals, and birds and concludes that the potential risks in Red Butte Creek are similar to other Salt Lake Creeks. The ecological risk assessment is currently available for public comment.

What's Next?

The DWQ is giving the local community an opportunity to provide comments on the human health risk and ecological risk assessments. The documents are available to the public during a comment period of 30 days beginning July 12, 2012 and ending August 13, 2012. Comments can be submitted by mail, e-mail or fax: Mr. Chris Bittner, DWQ, P.O. Box 1448870, SLC, UT 84124-8870, FAX 801-536-4301.

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