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Midlothian, TX Ambient Air Collection & Analytical Chemical Analysis

Describes study for which the TCEQ has contracted to collect samples to address citizen concerns.

 

Background

The Texas Department of State Health Services (DSHS) released a draft health consultation in December, 2007, for Midlothian, Texas: Midlothian Area Air Quality Part 1: Volatile Organic Compounds (VOCs) and Metals. In the consultation DSHS classified Midlothian as an indeterminate public-health hazard. The main bases listed for this classification are:

  • 18 out of 87 compounds for which health-based screening values were not available were above the DSHS-calculated average background levels.
  • Data are not available on the relative proportions of chromium VI to total chromium in Midlothian.
  • The EPA National Ambient Air Quality Standards (NAAQS) compounds still need to be evaluated in a future evaluation.
  • DSHS viewed the existing data set as having data gaps.

Therefore, the TCEQ has contracted with URS Corporation for the collection and analytical chemical analysis of ambient air samples in Midlothian. The purpose of collecting these samples is to attempt to answer citizen questions and concerns with regard to air quality in their city, as well as potentially to fill data gaps noted in the DSHS consultation. Citizen questions include:

  • How are industries in Midlothian affecting air quality?
  • Is the TCEQ every-6th-day monitoring site an accurate representation of daily air concentrations?
  • What is the air quality close to schools and parks in Midlothian?
  • What percentage of total chromium does chromium VI represent in Midlothian?

What Does This Study Seek to Accomplish?

This year-long study will collect ambient air samples at approximately eight sites in and around the city of Midlothian. Concentrations of metals and VOCs will be compared to the existing air-monitoring database. Chromium VI samples will be collected and percentage of chromium VI to total chromium will be determined for the Midlothian area. Once the study is complete all data will be publicly available via the TCEQ Web site.

Work Plan, QAPP, & QA Audit

In Adobe Acrobat PDF Document Portable Document Format (PDF) format (Help with Downloading PDF)

Historical Data

1st Quarter Sampling

In Adobe Acrobat PDF Document PDF format (Help with Downloading PDF)

2nd Quarter Sampling

In Adobe Acrobat PDF Document PDF format (Help with Downloading PDF)

3rd Quarter Sampling

In Adobe Acrobat PDF Document PDF format (Help with Downloading PDF)

Note: During the 3rd quarter sampling there was a laboratory chain of custody mix-up in which the hexavalent chromium samples could not be matched to their respective sampling date. More detailed information on the mix-up may be found in the URS Memorandum: Midlothian Third Quarter Hexavalent Chromium (Cr6+) and Total Unspeciated Chromium (CrT) Measurement Results and the letter from ERG to Al Hendler with URS dated June 9, 2009.

4th Quarter Sampling

In Adobe Acrobat PDF Document PDF format (Help with Downloading PDF)

Reports

In Adobe Acrobat PDF Document PDF format (Help with Downloading PDF)

Evaluation of the Midlothian, Texas Ambient Air Collection & Analytical Chemical Analysis Data

Adobe Acrobat PDF DocumentFinal Evaluation



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