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## OE'C Q 1 2009

Ted Schade Air Pollution Control Officer Great Basin Unified Air Pollution Control District 157 Short Street Bishop, California 93514

Dear Mr. Schade: Thank you for submitting the Great Basin Unified Air Pollution Control District's 2009 Ambient Air Quality Monitoring Network Plan. We have reviewed the submitted document and have found that it meets the minimum requirements set forth under 40 CFR Part 58.10. The comments enclosed with this letter identify several areas in the Plan where additional information is requested in order to complete the document and fully satisfy the requirements of 40 CFR Part 58.10. Rather than attempt to resolve these data gaps in this document, we request that GBUAPCD address the enclosed comments in next year's annual network plan which is due on July 1, 2010. If you have any questions regarding this letter or the enclosed comments, please feel free to contact me at (415) 947-4226 or Michael Flagg at (415) 972-3372.

Office

cc: Christopher Lanane Michael Flagg

Printed on Recycled Paper

### EPA Comments on the 2009 Ambient Air Quality Monitoring Network Plan

40 CFR 58.10(a)(1) states that monitors must meet Appendix A, C, D, and E. The following information from these appendices should be included in the plan. Appendix A: ® Frequency, of flow rate verification for manual PM samplers audit (App A, 3.3.2) ® Frequency of flow rate verification for automated PM analyzers audit (App A, 3.2.3) ® Last two semi-annual flow rate audits for PM monitors (App A, 3.2.4 and 3.3.3) ® PEP audit dates Appendix D: ® To ensure network meets minimurn monitoring requirements, the MSA population, and design value should be included for each pollutant. Appendix E: ® For each site: • Distance from nearest road • Traffic count of nearest road • Surrounding groundcover (e.g. paved, vegetated, etc.)

® For each monitor: o Probe height o Distance from structure • Distance from obstructions on roof • Distance from obstruction not on roof • Distance from trees o D.istance to furnace or flue • Distance between collocated monitors • Unrestricted airflow 

# in degrees 40 CFR 58.10 (b) • Location of each site: street address and geographic coordinates • Identification of sites suitable and sites not suitable for comparison to the annual PM2.5 NAAQS as described in 40 CFR 58.30 The "Detailed Site Information" table shown below is an example of how site information can be organized to ensure that each site and monitor meet the necessary regulatory requirements.

# Detailed Site Information

Site Name AQS ID GIS coordinates Location In shed, on school, etc. Address County Dist. to road meters Traffic count # Groundcover Paved, ve etated, etc. Representative Area List MSA or CSA (indicate which)

Pollutant 03 PM2.5 Monitor ob' List ob'ective List ob'ective S atial scale List scale List scale Sampling method List instrument Sampling instrument Analysis method N/A e.g., weighed by X lab Start date Date when

o eration be an Date when

o eration began O eration schedule e.g., 1:1 e. ., 1:3, Sam ling season e. ., May-Nov. e.g., all year Probe hei ht meters meters Distance from supporting structure meters meters

Distance from obstructions on roof meters meters

Distance from obstructions not on roof ' meters meters

Distance from trees meters meters
Distance to furnace or incinerator flue N/A meters
Distance between collocated monitors N/A meters

Unrestricted airflow degrees degrees

Probe material e.g., Teflon N/A Residence time X seconds N/A Will there be changes within the next 18 months? Y/N Y/N

Is it suitable for comparison against the annual PM2.5? N/A Yes for all current sites in Region 9. Fre uency of flow N/A weekly, bi-weekly,rate verification for monthly, quarterly

manual PM (high vol) sam lers audit Frequency of flow N/A weekly, bi-weekly, rate verification for monthly, quarterly automated PM (high vol)? analyzers audit Frequency of one- daily, weekly, bi- N/A point QC check weekly? (gaseous) Last Annual date N/A Performance Evaluation ( aseous) Last two semi- N/A dates annual flow rate audits for PM monitors