UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

REGION IX 

75 Hawthorne Street 

San Francisco, CA 94105 

November 1, 2011

Donald Gabrielson, Director

Pinal County Department of Development Services

Air Quality Control District

P.O. Box 987

Florence, Arizona 85232

Dear Mr. Gabrielson:

Thank you for your timely submission of the Pinal County 2011 Annual Monitoring Network Plan and 

2010 Data Summary. We have reviewed the submitted document and have found that it is complete, 

informative, very detailed and meets all of the requirements for annual network plans as required by our 

regulations set forth under 40 CFR Part 58.10. We specifically acknowledge the discontinuation of the

Maricopa County Complex Ozone and Combs School Ozone SPMs per 40 CFR Part 58.20 (f). While 

this letter serves as official approval of the annual network plan, it does not constitute approval of 

system modifications that may take place in the future. Also, approval of the Riverside Maintenance 

Yard and Mammoth County Complex PM10 monitor shutdowns will be addressed in separate 

correspondence. We will continue to work with your district to review system changes as they proceed.

If you have any questions regarding this letter or enclosed comments, please feel free to contact me at 

(415) 972-3851 or Michael Flagg at (415) 972-3372.

Sincerely,

/s/

Matthew Lakin, Manager

Air Quality Analysis Office

Air Division

Enclosure

cc: Mike Sundblom, PCAQCD

Kale Walch, PCAQCD
Comments on 2011 Annual Monitoring Network Plan and 2010 Data Summary

Please update next year’s annual network plan to reflect the following comments:

The sampling frequency for the Cowtown PM2.5 monitor should be included in Table 3.9: PM2.5 

Sampling Frequency. The plan indicates that the Cowtown monitor, which determines the design 

value for the area, is not meeting the monitoring frequency requirements of 40 CFR Part 58.12 

(d)(1). While the plan discusses the possibility of maintaining an FDMS TEOM to measure daily 

PM10 and PM2.5 in the future, changes to the sampling frequency should be made as soon as 

possible in order to ensure compliance with 40 CFR Part 58.12 (d)(1). 

While 40 CFR Part 58.20 states that SPM monitors may not be used to show compliance with the 

minimum monitoring requirements, SPM monitors should be included in the assessment of the 

number of minimum monitors that are required. For example, the Cowtown PM2.5 design value 

should be included in the analysis in Table 3.8: Minimum Monitoring Requirements for PM2.5, as 

data from this monitor are valid for comparison to the PM2.5 NAAQS per 40 CFR 58.20 (c). 

Similarly, PM10 SPMs operating more than 24 months should also be considered in assessing 

minimum PM10 monitoring requirements.

The Casa Grande Downtown information in Appendix B should be updated to match recent 

changes to the network that were identified in Section 5.0: Proposed Changes to the Network 

Specifically, the method code (126) and classification (SPM) need to be updated to 079 and 

SLAMS, respectively. 

It would be helpful and very informative if the site descriptions in Appendix B indentified the 

POC number for each instrument.