UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

REGION IX 

75 Hawthorne Street 

San Francisco, CA 94105 

April 12, 2013

William Wiley, Director

Maricopa County Air Quality Department 

1001 North Central Avenue Suite #500

Pheonix, Arizona 85004

Dear Mr. Wiley, 

Thank you for your submission of the Maricopa County Air Quality Department’s “2011 Air 

Quality Network Plan” in October 2012. Based on the information provided in the plan, EPA

approves all portions of the network plan except those specifically identified below. 

Annual network plans are important documents for regulatory purposes (e.g., State 

Implementation Plans, designations and redesignations) and public information, in addition to 

the myriad uses by the air districts. EPA is revising the review process for annual network plans 

to specifically check and document the comprehensive set of items that are required to be 

included in the annual network plans per 40 CFR 58.10 in a consistent manner. We have created 

a checklist that lists all these items and have included it as Attachment A. While the items in the 

checklist are required by EPA regulations, we acknowledge that we have not specifically 

requested some of this information in previous annual network plan reviews. We recognize that 

your plan may not have all the items that we have currently identified and hope to work with you 

on the inclusion of these items in future plans. To facilitate these changes, EPA has provided 

detailed feedback in the checklist where information should be included or revised in next year’s 

plan.

Please note that we cannot approve portions of the annual network plan for which the 

information in the plan is insufficient to judge whether the requirement has been met, or for 

which the information, as described, does not meet the requirements as specified in 40 CFR 

58.10 and the associated appendices. EPA Region 9 also cannot approve portions of the plan for 

which the EPA Administrator has approval authority. Accordingly, we are not acting on the 

specific portions of your agency’s annual network plan listed in Attachment B.

In addition to the checklist and list of specific plan elements where EPA Region 9 is not taking 

action, enclosed are additional detailed comments on the plan (Attachment C). All of the 

comments in Attachments A, B, and C should be addressed in next year’s network plan. If you 
have any questions regarding this letter or the 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

Enclosures:

A. Annual Air Monitoring Network Plan Checklist

B. Elements where EPA is Not Taking Action

C. Additional Detailed Comments

D. Public Comments Confirmation Email

cc: Ben Davis, MCAQD
Attachment B: Annual Air Monitoring Network Plan Items where EPA is Not Taking 

Action

We are not acting on the portions of annual network plans where either EPA Region 9 lacks the 

authority to approve specific items of the plan, or EPA has determined that a requirement is 

either not met or information in the plan is insufficient to judge whether the requirement has 

been met.

 NCore and the plan for NO2 monitoring require EPA Administrator approval. Per 40 CFR 

58.11(c), NCore and network design and changes are subject to approval of the EPA 

Administrator and per 40 CFR 58.10(a)(5) plans for establishing NO2 monitoring sites 

are submitted to the EPA Administrator for action. Therefore, we are not acting on these 

items.

 EPA identified items in you agency’s annual network plan where a requirement was not 

being met or information in the plan was insufficient to judge whether the requirement 

was being met based on 40 CFR 58.10 and the associated appendices. Therefore, we are 

not acting on of the following items:
Item Checklist Row 

(Attachment A) Issue

Sampling schedule for PM2.5 45 Insufficient to judge

Sampling schedule for PM10 46 Insufficient to judge 

PM2.5 co-location 32 Insufficient to judge 

PM10 co-location 33 and 34 Insufficient to judge 

Dates of last two semi-annual flow 

rate audits for PM monitors 30 Insufficient to judge 

Date of last Annual Performance 

Evaluation (gaseous) 29 Insufficient to judge 

Pb co-location 35 Insufficient to judge 

Frequency of one-point flow rate 

verification for Pb samplers audit 27 Not meeting requirement 

Dates of last two semi-annual flow 

rate audits for Pb monitors 31

Insufficient to judge 

Instrument/monitoring method code 37 Insufficient to judge 

Instrument parameter code for each 

instrument 42 Insufficient to judge 

Parameter occurrence code 42 Insufficient to judge

Statement of purpose 2 Insufficient to judge 

Monitoring objective 40 Insufficient to judge 

Distance of site from nearest road 62 Insufficient to judge in some 

instances 

Distance from supporting structure 66 Insufficient to judge 

Distance from obstructions on roof 67 Insufficient to judge 

Distance from obstructions not on roof 68 Insufficient to judge 

Additional information for each of these items is in included in Attachment A.
Attachment C: Additional Detailed Comments

 Per 40 CFR 58 Appendix D, section (2)(e), the EPA Regional Administrator and state or 

local agencies ... “may divide the overall MSA/CSA monitoring responsibilities and 

requirements among the various agencies to achieve an effective network design. Full 

monitoring requirements apply separately to each affected State or local agency in the 

absence of an agreement between the affected agencies and the EPA Regional 

Administrator.” For future plans, please state if an agreement has been made to share 

network design responsibilities for any MSAs in your jurisdiction and attach 

documentation.

 [Items 9-10] Although EPA Region 9 is not taking action on the NO2 portions of the 

plans this year, for next year, please identify sites fulfilling the NO2 area-wide and RA40 

requirements.

 [Item 39] Zuni Hill site has conflicting information for the instrument monitor type for 

each instrument. Page 104 reports the monitor as SLAMS, while page 28 reports it as

special purpose. Please clarify this information in next year’s plan. 

 [Item 51] Minimum monitoring requirements are met with two existing SO2 monitors, 

however please include the analysis for determining minimum number if ambient 

monitors required. 2008 NEI data indicate 2,067 total SO2 (tons/year), which is 

inconsistent with the estimate of 81.2 tons/year included in this year’s plan. Please 

correct, if necessary, for next year’s plan. 

 [Item 60] Although the plan notes that the minimum monitoring requirement for PM10 is 

met (pg. 30), please include information on the analysis of population category indicating 

whether the site is categorized as low, medium, or high concentration in next year’s plan.