BENZENE BY THE NUMBERS
Here is a look at the cancer risk associated with benzene exposure compared with the recent levels state environmental officials have reported at a compression facility in Denton County since October.
Texas’ lifetime exposure threshold: 1.4 parts per billion
Level for lifetime cancer risk of 1 per 1 million: 0.04 ppb
Level for lifetime cancer risk of 1 per 100,000: 0.4 ppb
Level for lifetime cancer risk of 1 per 10,000: 4 ppb
Level found at Devon plant on Jim Baker Road on Oct. 14: 46 ppb
Amount released in 2008, as reported by Texas companies: 1.9 million pounds
Amount released in 2008, as reported by Denton County Barnett Shale operators: 0
SOURCES: Texas Commission on Environmental Quality, Environmental Protection Agency
"These PBR proposals are just a part of what the TCEQ is doing to ensure safe air in the Barnett Shale," said TCEQ Commissioner Carlos Rubinstein. "Another important step is installing new, state-of-the-art, long-term air quality monitors in the area. Long-term monitors are the gold standard when it comes to scientific determination of potential emission impacts. We have installed two new monitors, and have plans for three more. So far these new monitors are showing very low levels of benzene and other chemicals in ambient air."
As an adjunct to these rules, the TCEQ recently completed phase one of its special inventory to determine the location, number, and type of emissions sources located at upstream and midstream oil and gas operations within the Barnett Shale formation. The TCEQ has received special inventory data from companies that account for more than 99 percent of the 2009 production in the Barnett Shale formation.
Phase two of the special inventory is undergoing final tweaks and will begin this summer. It will require data on actual emissions; emissions sources; proximity to nearest off-site receptor; existing authorizations, and other information.
The two new monitors, in DISH and Eagle Mountain Lake area, join existing monitors in Fort Worth and Dallas. A new monitor is being installed in Flower Mound, and locations are being determined for a monitor in Tarrant County and an additional location in the Barnett Shale. Hourly results from these monitors can be found at the TCEQ Barnett Shale website, as well as information to assist in interpreting the monitoring data.
The TCEQ’s regional office in Fort Worth has added seven new air inspectors to respond to air monitoring complaints quickly. In most cases, responses to complaints are handled within a few hours of receiving the complaint. Using the GasFind IR cameras and/or hand-held volatile organic compound samplers, about 550 sites have been surveyed since Aug. 1, 2009. More than 275 canister samples, as well as mobile Real-Time Automated Gas Chromatograph samples, have been collected. Only two samples have been found above short-term levels of concern, and those facilities were quickly repaired. Further sampling at those sites showed very low levels of benzene emissions.
Of course Benzene levels are reported as safe because the TCEQ has raised the short term ESL by 136% and the long term ESL by 50% from 2008 to 2010.