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 “ 201 1 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 ann ual 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 includ ed 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 t he 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 y ear’s

plan.

Please note that we cannot approve portions of th e 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 requireme nts 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 youhave 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

- 3 372

.

Sincerely,

/s/

Matthew Lakin, Manager

Air Quality Analysis Office

Enclosure s :

A. Annual Air Monitoring Network Plan Checklist

B. Elements where EPA is Not Tak ing Action

C. Additional Detailed Comments

D. Public Comments Confirmation Email

cc: Ben Davis, MCAQDAttachment B : Annual Air Monitoring Network P lan I tems where EPA is N ot 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 NO 2 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 NO 2 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 th e following items:Item Checklist Row

(Attachment A) Issue

Sampling schedule for PM 2.5 45 Insufficient to judge

Sampling schedule for PM 10 46 Insufficient to judge

PM 2.5 co

- location 32 Insufficient to judge

PM 10 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

abs ence 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.

 [ Ite ms 9

- 10] Although EPA Region 9 is not taking action on the NO 2 portions of the

plans this year, for next year, please identify sites fulfilling the NO 2 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 SO 2 monitors,

however please include the analysis for determining minimum number if ambient

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

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

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

 [Item 60] Although the plan notes that the minimum monitoring requirement for PM 10 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.