City of Fort Worth Air Quality Study
Comprehensive air quality study provides insight into emissions from natural gas facilities
Posted July 14, 2011
A comprehensive evaluation of gas exploration and production sites “did not reveal any significant health threats” and showed that “Fort Worth’s 600-foot setback distance is adequate.” However, some gas production facilities—like compressor stations—may require additional review.
Those are some of the conclusions from a third-party study by Eastern Research Group, Inc. (ERG) who was chosen by a local Air Quality Study Committee to answer questions about air quality impacts of natural gas exploration and production. ERG was also asked to determine the potential health risks associated with any air quality impacts, quantify the total amount of pollutants being emitted, and determine if natural gas sites were in compliance with air quality regulations.
ERG delivered its final report to the city of Fort Worth yesterday. A full copy of the study results can be found on the city of Fort Worth’s website at www.fortworthgov.org. City staff intends to conduct a thorough review of the study findings in the coming weeks with the goal of providing the City Council its own conclusions and recommendations.
“It’s good to hear that ERG didn’t find an immediate health risk from these gas production sites, but that doesn’t mean that there isn’t more we, the state and the natural gas industry can do to reduce emissions in a region that already has severe air quality challenges,” said Fort Worth Mayor Betsy Price. “The health and safety of our citizens must be our top priority. My council colleagues and I will review this report thoroughly and look forward to hearing from ERG directly next week.”
ERG began field testing in August 2010. The study included sampling at 388 gas well and gas transportation sites (including more than 1,000 active wells and more than 1,200 storage tanks). ERG was able to capture emissions samples from all stages of the gas production process. In the end, the study included unannounced up-close point source testing, ambient air monitoring, air dispersion modeling, a public health evaluation, a regulatory assessment and full build-out estimates.
A few of the major points of the study’s findings include:
- Ambient air monitoring, which included analysis of more than 15,000 data points, revealed no site-related pollutants above health-based screening levels established by the Texas Commission on Environmental Quality (TCEQ).
- For the overwhelming majority of sites considered in this study, the modeling results indicate that Fort Worth’s 600-foot setback distance is adequate to protect public health.
- A total of 2,126 emission points were identified in the four-month field study with the Infrared (IR) Camera and Toxic Vapor Analyzer (TVA).
- While 96 sites had no detectable emissions with the infrared camera, when emissions were detected, the primary sources were tank thief hatches, pneumatic valve controllers, tank vents and natural gas pressure regulators.
- More than 130 sites that included compressors were visited. Of those, five particular sites may have overall emission rates that exceed regulatory thresholds that are supposed to trigger certain TCEQ permitting requirements. The emissions from these compressor sites were calculated using the best information available from the EPA.
The following are the main questions asked of ERG at the beginning of the Air Quality Study, followed by excerpts of the responses from ERG based on its analysis:
1. What quantity of emissions is coming from natural gas exploration and production sites located within the City of Fort Worth?
“ERG estimated emissions for 375 well pads, eight compressor stations, one gas processing plant, a salt water treatment facility, a drilling operation, a fracking operation and a completion operation. Summed across all of these sites, the total estimated emissions of organic compounds was 20,818 tons per year…Pollutants with relatively low toxicities (e.g., methane, ethane, propane, and butane) accounted for the overwhelming majority—approximately 98 percent—of the citywide emissions. However, several pollutants with relatively high toxicities (e.g., benzene) were also emitted from these sites, though in considerably lower quantities.” – ERG
2. Do the sites comply with applicable regulatory limits?
“Based on the emission rates that ERG calculated for this project, five sites—a processing facility, three compressor stations, and one well pad—had overall emission rates that exceed regulatory thresholds that are supposed to trigger certain permitting requirements.” – ERG
3. How do releases from these sites affect off-site air pollution levels?
“A health-screening analysis of the measured and estimated air pollution levels identified three pollutants—acrolein, benzene, and formaldehyde—as the most important from a risk perspective. While Fort Worth residents are exposed to these and other pollutants released from natural gas sites, the measured and estimated air pollution levels did not reach levels that have been observed to cause adverse health effects. Further, the measured benzene and formaldehyde levels in Fort Worth were not unusually elevated when compared to levels currently measured by TCEQ elsewhere in Texas. There was insufficient data available to do a similar comparison for acrolein.” – ERG
4. Are the city’s required setbacks for wells, tanks and compressors adequate to protect public health?
“For the overwhelming majority of sites considered in this study, the modeling analysis indicates that Fort Worth’s 600-foot setback distance is adequate. For the relatively few sites with multiple, large line compressor engines, the modeling analysis found some areas beyond the setbacks to have estimated acrolein and formaldehyde concentrations greater than protective health-based screening levels published by TCEQ. However, the estimated air pollution levels did not reach levels that have actually been found to cause symptoms or illness among exposed populations.” – ERG
Although ERG’s study did not reveal any significant health threats beyond setback distances, ERG did recommend that “all reasonable precautions to reduce emissions from the well pads and compressor stations should be made.” Such precautions, ERG reported, might include the installation and operation of air pollution control equipment such as vapor recovery units, catalytic oxidizers on compressor engines, electric compressor engines and low bleed pneumatic valve controllers.
ERG representatives will present their study findings to the Fort Worth Air Quality Committee at 3 p.m. Monday, July 18 in the Pre-Council Chamber at City Hall, 1000 Throckmorton St. The City Council will be briefed by ERG on the study results at 8:30 a.m. July 19 also in the Pre-Council Chamber. ERG also will host a meeting for the general public at 6 p.m. July 19 in the Council Chamber at City Hall.
Questions about the Air Quality Study results can be emailed to [email protected]. Those questions will be answered and also may be added to the frequently asked questions list to be posted on the city’s website.