UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

Ref: 8P-AR 

Ms. Cara Keslar 

Monitoring Section Supervisor 

REGION 8 

1595 Wynkoop Street 

DENVER, CO 80202-1129 

Phone 800-227-8917 

http://www.epa.gov/region08 

FEB 2 9 2012 

Wyoming Department of Environmental Quality 

122 West 25th Street. 2-E 

Cheyenne, Wyoming 82002 

Dear Ms. Keslar: 

Thank you for submitting the 2010 and 201 1 Wyoming Ambient Air Monitoring Annual Network Plans, 

both of which were submitted under lett rs dated June 27, 2011. This letter presents our comments on 

the plans and documents our approval. Region 8 also reviewed the Wyoming Ambient Monitoring 

Network Assessment 2010, which was submitted under a letter dated July 15,2011. Although 

regulations do not require formal concurrence on a network assessment by the Region, we find the 

assessment very useful and appreciate the effort that the Air Quality Division put into this effort. 

The network plans describe new air monitoring stations that have been added to the network since the 

network plan of September 2009. Excepl for the National Core multi pollutant monitoring (NCore) 

station in Cheyenne, these stations have not been documented in network modification forms submitted 

to Region 8. Network modification requ st forms describe the instruments to be installed in a station and 

the station ·s elevation, probe siting. nearby land use and related details. The information on the forms 

augments the network planning and asse sment processes described in 40 CFR 58.1 0. 

An example of a station with incomplete documentation in Region 8's files is the Boulder special 

purpose monitor (SPM) station in Sublette County, with AQS identification number 56-035-0099. This 

station, which has been running since 2005, monitors the criteria pollutants nitrogen dioxide, ozone and 

PM 10. I3oulder is the station most frequently reporting the maximum concentration of ozone in Sublette 

County. Since the Boulder SPMs have run for more than two years, their data may be used for 

comparison to the National Ambient Air Quality Standard, consistent with 40 CFR 58.20. However, the 

network plan docs not state that the I3oulder station meets probe siting criteria and otherwise meets 

criteria for regulatory monitoring. r urther·more, Region 8 does not have supporting documentation from 

the Air Quality Division (such as in a site file or complete site and monitor data in AQS). 

Although it contains some exemptions for SPMs, 40 CFR 58 states that, with respect to State and Local 

Air Monitoring Stations (SLAMS), NCore, SPM and speciation stations, a network plan '·shall include a 

statement or purposes lor each monitor ahd evidence that siting and operation of each monitor meets the 

requirements of appendices A, C, D, and E of this part, where applicable." We recommend that future 
network plans include evidence that the air monitoring stations. including SPMs. meet regulatory criteria 

equivalent to SLAMS. This evidence may be shown concisely ~ modifying the table in appendix A or 

the plan, including an appendix of recent network modification ~quest forms, a separate tile or similar 

documentation. 

Section 40 CFR 58.20 states that, "The monitoring agency must also submit to AQS an indication or 

whether each SPM reporting data to AQS monitor meets the requirements of appendices A and E to this 

part." We suggest that the AQD enter the required information in AQS for the special purpose monitors 

as well as the SLAMS. This would include information frequenqy missing from the Division's monitor 

and site information in AQS. such as probe height. probe location, measurement scale. sample residence 

time and unrestricted air flow. The network modification form was designed to include these essential 

regulatory monitoring criteria, so that the information recorded oh the network modification form is then 

readily available for AQS input. We understand that the AQD is working to bring site Iiles up to date by 

completing network modi tication forms, consistent with the Wyoming/EPA Performance Partnership 

Agreement, Fiscal Year 2012. We also understand that the AQD will be prepared to address site 

documentation during the systems audit that Region 8 plans to c nduct in Wyoming this year. 

One of the air monitoring stations in Pinedale discussed in section 2.2.8 of the 20 II network plan is on 

the west side of City Park and Pine Creek and has the AQS identification number 56-035-0 I 0 I. This 

station houses a continuous PM2.s analyzer, an analyzer measuring ozone and another measuring oxides 

of nitrogen. The continuous PM2.s analyzer is a Met One Instruments, Inc. BAM-I 020 Beta Attenuation 

Mass Monitor with a very sharp cut cyclone particle size separatbr (EPA equivalency designation 

EQPM-0308-170). 

With respect to this continuous PM2.5 analyzer, section 2.2.8 refers to the .July 24, 2008 EPA 

memorandum, "Implementing Continuous PM2.5 Federal Equivalent Methods (FEMs) and Approved 

Regional Methods (ARMs) in State or Local Air Monitoring Station (SLAMS) Networks:· The J\QD 

correctly cites the memorandum as giving guidance for long-teny evaluation of an FEM, and Region 8 

supports the AQD's evaluation of the beta-attenuation method iq Pinedale. Data collected in 20 I I by 

this PM2.

5 analyzer in Pinedale were coded in AQS as both "special purpose·' and "non-regulatory:· 

Consistent with EPA's 2008 memorandum, Region 8 concurs in this reporting convention. Also 

consistent with that memo. we would support the AQD's revisiting the monitor type in the 2012 

monitoring plan. The 20 II network plan showed the BAM-I 020 in use to monitor PM2.s at three 

permanent air monitoring stations in Wyoming (as well as in the three mobile air monitoring stations); 

accordingly, we also encoW"age the AQD select a site for colloc~~ing a reference-method PM2.s sampler 

with this method. 

I r you have any questions or comments, contact me at (303) 312-6431 or .Joe Delwiche of my staff at 

(303) 312-6448. 

Sincerely, 

,/- ,.~ 

i\_ -~c~~ Deirdre Ro hery, Chief (j · 

Air Permitting, Monitoring. & Modeling Unit