UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

REGION IX
75 Hawthorne Street San Francisco, CA 94105

November 1, 2011

Mr. Mike Sword, Engineering Manager Clark County Department of Air Quality and Environmental Management 500 S Grand Central Parkway, 1 st Floor

P.O. Box 555210 Las Vegas, NV 89155

- 5210

Dear Mr. Sword:

Thank you for your timely submittal of the 2011 Annual Monitoring Network Plan for the Clark County Department of Air Quality and Environmental Management (DAQEM). EPA has reviewed the

submitted document and found that it is c omplete, informative, very detailed and meets the requirements set forth under 40 CFR Part 58.10. We also appre ciate your addressing in full our comments to last year’s 2010 Network Plan. While this letter serves as an official approval of the annual net work plan, it does not constitute approval of future nor previous network modifications that are identified in the plan.

EPA will continue to work with DAQEM to review system changes as they proceed on a case

- by

- case basis and will respond separately to r equests already submitted

.

If you have any questions regarding this letter or the enclosed comments , please feel free to contact me at (415) 972

- 3851 or Elfego Felix at (415) 947

- 4 141

.

Sincerely,

/s/

Matthew Lakin, Manager

Air Quality Analysis Office

Air Division

Enclosure

cc: Yousaf Hameed, Monitoring Supervisor, DAQEMComments on 2011 Network Plan for Clark County DAQEM

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

1. 40 CFR 58.10(b)(3) requires that the sampling and analysis method(s) for each parameter measured be reported. EPA found that DAQEM’s current method for reporting this requirement is either lacking or unclear for multiple sites. In order to clarify and facilitate the reporting of this requirement, please implement the following:

o Remove this information from the overall site description section (located just beneath the site photographs) and incorporate it into the tables that include monitor specific information.

o To report appropriate FRM/FEM sampling and analysis method(s), please refer to the tables

listed towards the end of the List o f Designated Reference and Equivalent Methods . A link to

the latest List of Designated Reference and Equivalent Methods can be found at http://www.epa.gov/ttn/amtic/criteria.html . For the sampling method, please report the appropriate instrument name and model found under the table column labeled method . For the analysis method, please report the designation number found under the column heading Designation No.

o For non

- FRM/non

- FEM instruments, please report the full instrument name and model as the sampling method, and describe (or provide a reference to) the analysis method used.

2. 40 CFR 58.10 (b)(8) requires the MSA, CBSA, CSA or other area represented by each monitor be reported. DAQEM’s 201 1 Network Plan addresses this requirement on page 5 in the section titled “Metropolitan Statistical Area.” In order to clarify the content of this section and to better address the requirement, EPA recommends the following be implemented:

o Include a statem ent that clarifies that each of the monitors operated by DAQEM are contained within the Las Vegas

- Paradise Metropolitan Statistical Area.

o Remove the statement that reads: “the Cities of Mesquite and Boulder City, do not qualify as Metropolitan Statistical Areas.” This statement is inaccurate given that the Metropolitan Statistical Area encompasses all of Clark County. Since each of these cities resides within the boundaries of Clark County, they are each representative of this same MSA.

3. 40 CFR 58.10(b)(1 2) requires the identification of newly required NO 2 monitors based on the 2010 NAAQS revision to the primary NO 2 standard. Although DAQEM includes a discussion (pp.61) of new upcoming NO 2 monitoring in Clark County, an analysis for the actual number of

r equired sites based on most recent information is not included. Please ensure this analysis is included in next year’s plan.