UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

REGION IX

75 Hawthorne Street San Francisco, CA 94105

November 1, 2010

Mr. Lewis Wallenmeyer, Director 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. Wallenmeyer :

Thank you for your submittal of the 2010 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 complete, informative, very detailed and meets all of the requirements se t forth under 40 CFR Part 58.10. We

have included comments and recommendations for next year’s network plan. While this

letter serves as an official approval of the annual network plan, it does not constitute approval of the future system modifications t hat are proposed in the plan. Pending the gathering of further information that DAQEM has proposed, EPA will continue to work with your district to review system changes as they proceed on a case

- by

- case basis

.

We also want to thank you for your timely s ubmission of the 2010 Network

Assessment required under 40 CFR Part 58.10. We recognize that preparing the network assessment was a significant project and we appreciate your effort s

. EPA plan s to provide feedback regarding network assessments during the winter of 2011.

If you have any questions regarding this letter, 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

Enclosures

cc: Mike Sword, Engineering Manager, DAQEM Yousaf Hameed, Monitoring Supervisor, DAQEMComments on 2010 Network Plan for Clark County DAQEM

Please implement the following recommendations for next year’s network plan:

Major :

Mention of comments received/not received during public inspection of plan (pp.4): Any comments received during the public inspection period that is required of the annual monitoring network plan (40 CFR 58.10 (a) (1)) should be included along with the plan.
In the event that no comments are received, a statement reflecting this should be included in the plan

. DAQEM includes a section regarding the public inspection process, however

there is no mention of whether comments were received or not.

Statement of purpose for each monitor at site (pp.17

- 18): 40 CFR 58.10 (a) (1) requires that a statement of purpose for each monitor be included in the annual monitoring network plan. This may be addressed in the form of a descriptive site overview as long as the purpose of each monitor is mentioned. In genera l, Clark County DAQEM has done a good job addressing this requirement. N onetheless, for the following sites, a more detailed description should be considered: Boulder City, J.D. Smith, East Sahara, Mesquite, Orr, Winterwood. These site descriptions shoul d elaborate further on the purpose for each of the monitors. A more elaborate description would include things like primary pollution concerns, historical context, and relevant regulations.

Minor :

Inconsistency of Apex spatial scale reporting (pp.10

- 11, 24): It was noted that DAQEM initially had their Apex site PM10 and PM2.5 continuous monitors classified as Regional spatial scales (pp.10

- 11). The detailed site section for this station (pp.24) reports these

two monitors as representative of a Neighborh ood scale. EPA believes that the neighborhood spatial scale is the appropriate one and recommends that DAQEM correct this discrepancy so as to avoid confusion in future plans.

Unclear figures (pp.51, 53

- 55, 57

- 60, 62): DAQEM has provided several pages of very useful figures that represent the various pollutant specific monitoring locations. A few of the figures were difficult to decipher ( Figures 20, 22

- 24, 26

- 29, and 31 ). It is

recommended that DAQEM ensure that each of the included figures are published in a higher resolution

, such as that seen in Figures 21, 25, and 30 of the report

.