UNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGION 6 1445 ROSS AVENUE, SUITE 1200 DALLAS TX75202-2733



### JON 2 2011 Mark R. Vickery, P.G. Executive Director Texas Commission on Environmental Quality Post Office Box 13087 Austin, Texas 78711-3087 DearMr. Vickery: Overthe past year, the U.S. Environmental Protection Agency (EPA) and the Texas Commission on Environmental Quality (TCEQ) have been in discussions concerning the regulatory requirements ofthe TCEQ's Annual AirMonitoring Network Plan. We appreciate the progress thathas been made to date and it appears that the dialoghas been narrowed to one network design issue which still requires attention before the submittal ofthe TCEQ 2011 Annual Air Monitoring Network Plan. I appreciate yourreply on March 31, 2011, to the issues identified in the EPA's December23, 2010 letter, approving the TCEQ 2010 Annual AirMonitoring Network Plan. We would like to thank you for yourtimely response to ourletter and for the resolution ofthe majority ofthe issues; however, one critical issue still requires resolution. In our approval letter, we asked the TCEQ to confirm that the privately-owned ozone monitor atthe Wallisville Road sitebe include.d in the 2011 Network Plan as a special purpose monitor orthat a TCEQ monitorbe deployed at that location in orderto continue to meetnetwork adequacy requirements. (See 40 CFRPart 58, App. D., 1.1.1 et seq.) Yourresponse letter stated: "TCEQ declines to include the Wallisville Road site in the 2011 ANR or deploy a monitorto this location on the basis that the results from this site no longerjustifythis network revision. The results from this site are no longer among the highest ozone design values, as they were for 2007-2009. When compared to regulatory sites, results from Wallisville Road have dropped into a tie for fourth place, with a design value of81 ppb. The most recent results do notjustifYthis network change atthis time." Afterreceiving this response, the EPA and the TCEQ airmonitoring staffmet in Waco, Texas, on April 14, 2011, to further discuss and understand the issues potentially impacting the TCEQ monitoring network. , After careful review ofthe TCEQ's response letter and subsequent airmonitoring staff discussions, the EPA has not changed its determination thatthe Wallisville area ozone monitor is crucial to the adequacy ofthe TCEQ airmonitoring network. The EPA uses the criteria from 40 CFR Part 58, Appendix D, Section I to evaluate the adequacy ofthe airpollutant monitoring networks. According to 40 CFRPart 58, Appendix D, Section 1.1.1 (a) and (c), monitoring sites must be capable ofinforming managers about many things including the peak airpollution levels

Internet Address (URL) • http://www.epa.gov/region6 Recycled/Recyclable

_ Printed with Vegetable Oil Based Inks on 100% Recycled Paper, Process Chlorine Freenear specific sources. The Wallisvillemonitor falls underthe following two categories ofgeneral site types: (I) sites located to determine the highest concentrations expected to occur in the area coveredby the network, and (2) sites located to determine the impact ofsignificant sources or source categories on air quality. There are currently no TCEQ ozone monitors nearthe Wallisville ozone monitor. This monitoris

. the only ozone site on the east side ofHouston where there aremany significant industrial sources ofozone precursor emissions. While we understand that the site is no longer among the highest design values in the last couple ofyears, when we lookback since 2003, the Wallisville ozone monitorhas consistently recorded some ofthe highest 8-hour ozone concentrations in the Houston area (e.g., the Wallisville 2008-2010 8-hourozone design value is currently above the 2008 75 ppb standard at 81 ppb). The EPA understands thatthe TCEQ is not currently willing to certifY the data from the current ozone monitorbecause it is privately operated. IftheTCEQ cannot certifythe data, or even ifit does and the private owner ofthe currentmonitor decides to cease operation, itbecomes essential for the TCEQ to. establish their own monitor at this location and classify it accordingly as a State Local Area Monitoring Site (SLAMS) with site approval from the EPA in accordance with 40 CPR Part 58 App. D, 2(d). An ozone monitor at or within a one mile radius ofthe current Wallisville ozone monitor will ensure the m.onitoring network in Houston is adequate. The TCEQ's commitment for this ozone monitoring location mustbe included in the 2011 Texas Annual Network Plan with a start-up date no laterthan July 1, 2012 (one year after submittal ofthe 2011 Texas Annual NetworkPlan), for the EPA to approve the plan. The network assessmentprocess presents an opportunity for the EPA and the TCEQ to collaborate on network design issues related to 40 CPRPart 58 App. D, 1.1.2. Our continual goal is to work with you and your staffto ensure thatthe Texas air monitoring network satisfies all regulatory requirements. Ifyou have any further questions, please contact me at (214) 665-2100, oryour staffmay contact Ms. Maria Martinez ofmy staffat (214) 665-2230.