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

Dear Mr. Vickery:

Over the 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 Air Monitoring Network Plan. We appreciate the progress

that has been made to date and it appears that the dialog has been narrowed to one network

design issue which still requires attention before the submittal ofthe TCEQ 2011 Annual Air

Monitoring Network Plan.

I appreciate your reply on March 31, 2011, to the issues identified in the EPA's December 23,

2010 letter, approving the TCEQ 2010 Annual Air Monitoring Network Plan. We would like to

thank you for your timely response to our letter 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 at the Wallisville Road site be

include.d in the 2011 Network Plan as a special purpose monitor or that a TCEQ monitor be

deployed at that location in order to continue to meet network adequacy requirements. (See 40

CFR Part 58, App. D., 1.1.1 et seq.) Your response letter stated:

"TCEQ declines to include the Wallisville Road site in the 2011 ANR or deploy a

monitor to this location on the basis that the results from this site no longer justify this

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 of 81 ppb.

The most recent results do not justifY this network change at this time."

After receiving this response, the EPA and the TCEQ air monitoring 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 air monitoring staff

discussions, the EPA has not changed its determination that the Wallisville area ozone monitor is

crucial to the adequacy ofthe TCEQ air monitoring network. The EPA uses the criteria from 40

CFR Part 58, Appendix D, Section I to evaluate the adequacy ofthe air pollutant monitoring

networks. According to 40 CFR Part 58, Appendix D, Section 1.1.1 (a) and (c), monitoring sites

must be capable ofinforming managers about many things including the peak air pollution levels

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near specific sources. The Wallisvillemonitor falls under the following two categories of general

site types: (I) sites located to determine the highest concentrations expected to occur in the area

covered by 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 near the Wallisville ozone monitor. This monitor is .

the only ozone site on the east side ofHouston where there are many significant industrial

sources of ozone precursor emissions. While we understand that the site is no longer among the

highest design values in the last couple of years, when we look back since 2003, the Wallisville

ozone monitor has consistently recorded some ofthe highest 8-hour ozone concentrations in the

Houston area (e.g., the Wallisville 2008-2010 8-hour ozone design value is currently above the

2008 75 ppb standard at 81 ppb). The EPA understands that the TCEQ is not currently willing to

certifY the data from the current ozone monitor because it is privately operated. Ifthe TCEQ

cannot certify the data, or even ifit does and the private owner ofthe current monitor decides to

cease operation, it becomes 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 must be

included in the 2011 Texas Annual Network Plan with a start-up date no later than July 1, 2012

(one year after submittal ofthe 2011 Texas Annual Network Plan), for the EPA to approve the

plan.

The network assessment process presents an opportunity for the EPA and the TCEQ to

collaborate on network design issues related to 40 CPR Part 58 App. D, 1.1.2. Our continual goal

is to work with you and your staffto ensure that the Texas air monitoring network satisfies all

regulatory requirements. If you have any further questions, please contact me at (214) 665-2100,

or your staffmay contact Ms. Maria Martinez ofmy staff at (214) 665-2230.