(72d) Design and Implementation of a Large Facility Perimeter Air Monitoring Network

Solving the ozone non-attainment problem in the Baton Rouge, Louisiana airshed continues to be a technical challenge. Based on the Louisiana Department of Environmental Quality ambient monitoring activities in 2003-2004, and similar work in the Houston/Galveston Non-attainment area, the agency opted to pursue a strategy that would address Highly Reactive Volatile Organic Compounds (HRVOC). To assist in these efforts 15 industrial facilities in the Baton Rouge area, in partnership with LDEQ, installed ambient monitors with plans to operate them for a period of 2 years. The monitors needed to be capable of measuring a list of 44 compounds judged to be potential contributors to elevated ozone based on photochemical reactivity. Ambient monitoring stations currently operated in the Baton Rouge area by the LDEQ use a Total Non-methane Organic Carbon (TNMOC) analyzer, which runs continuously, and in the event of elevated TNMOC readings, a sample is collected in an evacuated Summa canister. The Summa canister is then manually changed out and the collected sample taken to an analytical laboratory for analysis. In designing our system, ExxonMobil felt it was important to find a way to obtain more "near real-time" results. By decreasing the amount of time elapsed between an event and having access to analytical results, we could increase our facility personnel's ability to quickly investigate and better identify possible sources of the elevated TNMOC levels.

Based on this premise, a decision was reached to have the TNMOC operate in conjunction with a Gas Chromatograph (GC) that would be triggered by elevated TNMOC concentrations. This system yields sample results for the 44 compounds within approximately one hour of the trigger event. This type of triggered GC is, to the best of our knowledge, the first triggered GC system in use for ambient monitoring in the U.S. The system captures passing HRVOC plumes more promptly and effectively than conventional Auto-GC monitors, which may miss the plumes or ?flatten? the peaks. The ability to rapidly obtain speciated information has greatly enhanced the facility's response efforts and allowed identification of potential sources of the elevated TNMOC that would not have been possible with the canister system. By using the facility monitoring results, in conjunction with the LDEQ's continuing fixed and mobile monitoring activities, we will be able to focus our control efforts on those areas needed to reduce ozone levels in the Baton Rouge non-attainment area.