UNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGION 8

Ref: 8P-AR
Mr. Gordon Pierce, Program Manager 1595 Wynkoop Street DENVER, CO 80202-1129 Phone 800-227-8917 http://www.epa.gov/region08



### MAR 1 3 2015

Technical Services Program-Air Pollution Control Division Colorado Department ofPublic Health and Environment 4 300 Cherry Creek Dr. S. Denver, Colorado 80246-1530
Re: 2013 and 2014 Annual Monitoring Network Plan
Dear Mr. Pierce:
Thank you for submitting the 2013 and 2014 Colorado Annual Monitoring Network Plans (AMNP) dated June 28, 2013 and July 1, 2014, respectively. EPA Region 8 has reviewed the submitted documents and found that all ofthe requirements specified in 40 CFR Part 58.10, as well as the 105 grant commitment to prepare a plan annually, have been met with the submission ofthese documents, with the exceptions to 40 CFR Part 58 Appendices A, D and E noted in the enclosure to this letter.
When AMNPspropose changes to the SLAMS monitoring network, the EPA regional office is required to approve or disapprove the planned SLAMS changes. Region 8has reviewed the submitted documents and the planned changes. Region 8 is approving the 2013 network changes detailed in the 2013 plan (termination ofmonitoring at Rist Canyon and inception ofPM2.s monitoring at Castlewood Canyon State Park) and is also approving the following proposed changes detailed in the 2014 plan:
1. Shutdown ofthe Highland Reservoir monitoring site during construction, with potential relocation 2. Installation ofmeteorological sensors at the Colorado Springs Highway 24 site 3. Installation ofa Second Near Roadway N02 monitoring site at I-25/Acoma Street and 49th Avenue in Denver 4. Waivers of40 CFR Part 58, Appendix E Section 4 and 5 siting requirements with respect to trees near the CAMP and Welby monitoring sites 5. Cessation ofPb sampling at Centennial Airport (pending a network modification request with a historical data assessment that includes 2014 data)The enclosure also includes three minor discrepancies which should be addressed in your 2015 AMNP and considerations for the 

### S02 DataRequirements Rule. Ifyou have any questions or comments, contact me at (303) 312-6416 or Richard Payton ofmy staffat (303) 312-6439.

Enclosure

cc: Pat McGraw, CDPHE Greg Harshfield, CDPHE Carl Daly, Director AirProgramEnclosure
1. Highland Reservoir shutdown: EPA understands this site is unavailable for an extendedperiod oftime due to construction in the area. EPA will work with CDPHE as needed in the future to eitherreinitiate monitoring at this site orto find a new location for monitoring in this area. In the meantime, EPA is approving the shutdown ofthis monitoring site.
2. Colorado Springs Highway 24 meteorological monitoring: Since CDPHE learned that this site would continue to be available as a monitoring location for the longer term, the state decided to add meteorological monitoring at this site. EPAunderstands that the meteorological data collected at this site will be more representative for the monitoring datathan the available airport meteorological site; therefore EPA is approving this network modification.
3. Near Road N02 monitoring: For the second Denver Core Based Statistical Areas (CBSA) near roadway 

### NOz site, 40 CFR Part 58, Appendix D Section 4.3.2(a)(l) specifies that:
Where one CBSA is required to have two near-road

### NOz monitoring stations, the sites shall be differentiated from each otherby one or more ofthe following factors: fleet mix; congestion patterns; terrain; geographic area within the CBSA; or different route, interstate, or freeway designation.
When inspected by EPA monitoring stafffrom Region 8 and the EPA Office ofAir Quality Planning and Standards (OAQPS) in December 2014, the EPA determined that while both the existing near roadway site and the proposed second site lie along I-25 within 4 miles ofeach other, the second site differs from the first with respect to fleet mix (6.3% trucks at 81 h Avenue, 10.9% trucks at 491hAvenue); congestion patterns; and terrain (8th Avenue is less than 10 feet above the level ofthe Platte River, while 49th Avenue is more than 50 feet above the level oftheriver, outside the immediate channel). In addition, the 49th Avenue site is within the Globeville area, and will measure near roadway

### NOz in an area identified inpublic comment letters to the Colorado Department ofPublic Health and Environment (CDPHE) as a local community concern. The two sites also present differences with respect to their relative proximity to the Denver central business district and major

### NOz point sources north ofthat district. Finally, the 49th Avenue location, 1mile east-northeast ofthe La Casa NCore site, presents opportunities for comparisons ofdata collected within 5 meters ofthe nearest freeway lane to data from a nearby site approximately 400 meters from the nearest freeway lane. Therefore, the EPA is approving the installation ofCDPHE's second near roadway

### NOz monitoring site at I-25/Acoma Street and 49th Avenue in Denver.
4. Siting Requirements Waiver: Regarding the waiver ofsiting requirements with respect to trees which have grown overthe years near the CAMP and Welby monitoring stations, both CAMP and Welby are among the longest continuously operated air monitoring stations in Colorado. CAMP is one ofthe longest running in the country, with CO, 

### NOz and S02 data in AQS extendingback to 1965. The EPA recommends CDPHE continue operation ofeach monitoring site, while acknowledging potential issues resulting from the nearby trees. In addition, the Welby stationhas been identified by the EPA as one ofthe 40 N02 sites nationwide 1providing the data required by 40 CFRPart 50, Appendix D, Section 4.3.4(a) (Regional Administrator (RA) Required Monitors), where "sitingthese monitors in locations to protect susceptible and vulnerable populations" is accomplished. Therefore, both waiver requests are approved.
Similarto the growth oftrees at Welby and CAMP and the waiver approval for those trees provided herein, staffofthe EPA have noted that the pine tree on the east side ofthe Boulder Chamber of Commerce site may also need a waiver ofthe 40 CFR Part 58, Appendix E Section 4 and 5 siting requirements for continued operation. CDPHE may wish to include a waiver request for that site in the 2015 AMNP.
5. Lead Monitoring: Lead monitoring at Centennial Airport, which was initiated in 2010, was based on early emission calculations showing that annual lead emissions from aircraft operations at Centennial exceeded 1 ton/year. The monitoring requirement in Appendix D, Section 4(a) calls for monitoring at "each airport which emits 1.0 or more tons peryear based on either the most recent National Emission Inventory 1or other scientificallyjustifiable methods and data (such as improved emissions factors or site-specific data)." National Emission Inventory (NEI) data for Centennial Airport lead emissions were 0.73 tons in the 2008 NEI, and 0.83 tons in the 2011 NEI, so lead monitoring is no longer required at Centennial unless alternative scientificallyjustifiable methods and data indicate recent emissions were in fact greater than 1ton/year. 40 CFR Part 58, Appendix D, Section 4.5(a)ii allows the EPA RA to waive source oriented lead monitoring requirements ifstate monitoring agencies can demonstrate that emissions from the lead source targeted by a source oriented monitor will not contribute to concentrations in ambient air greaterthan 50% ofthe lead National Ambient Air Quality Standard (NAAQS, 0.15 f.lg/m3

, 3 month average). Lead data collected at Centennial in 2010 through October 2014 show no three month average lead above 0.02 f.lg/m3• Iffourth quarter 2014 data, not yet in AQS, show comparable levels, then CDPHE could use this data to complete the network modification request submitted March 9, 2015 in accordance with Appendix D, Section4.5(a)ii. Exceptions to 40 CFR Part 

### 58, Appendices A, D and E compliance: In addition to proposed changes to the SLAMS network whichrequire EPA regional office approval, AMNPs are required in 40 CFR Section 58.10 "to provide evidence that siting and operation ofeach monitor meets the requirements ofAppendices A, C, D, and E ofthis part, where applicable." While CDPHE's 2013 and 2014 ANMPs in general provide this evidence, instances in which the current CDPHE ambient air monitoring network is not compliant with 40 CFR Part 58, Appendices A, D and E have been identified during the EPA regional office review ofthe plans and are described below. The EPA recommends that CDPHE review these exceptions and work toward a resolution to ensure monitoring network compliance.


### PM2.s Precision: Specifically, 40 CFRPart 58, Appendix A, Section 3.2.5.1 requires that each designated PM2

.s Federal Reference Method (FRM) and Federal Equivalent Method (FEM) used in a monitoring network have 15% ofthe sites using eachmethod collocated with a second precision sampler. The EPA notes that the PM2.s monitors at Cortez and Castlewood Canyon State Park use the Partisol2000 manual FRM PM2.s samplers, but neitherthey nor any other site in the CDPHE

1NEI data available at http://www

.epa.gov/ttnlchief/eiinformation.html 2network has a collocated pair ofPartisol 2000 samplers. The Cortez and Castlewood Canyon datatherefore do nothave any precision data with whichthe data collected by the samplers can be validated. The data from the monitors is not accompanied by appropriate quality assurance data which would allow the data to be used for regulatory purposes. EPA recommends that an additional Partisol 2000 ofthe same method type be deployed at a site already using the Partisol 2000 method in orderto collect a collocated sample every 12th day as required by Appendix A. Alternatively, the Partisol2000 sampler(s) in the network could be replaced with Partisol 2025 samplers, which already meetAppendix A collocationrequirements. EPA notes that even thoughthe Castlewood Canyon State Park site was included inthe 2013 and 2014 plans, as of January 1, 2015, the site is no longer in operationper CDPHE's network modificationrequest, thereby resolving this issue for that site.
NCore 

### PMto-2.s: Appendix D, Section 3.2(b) requires PMI0-2.5 monitoring atNCore, and has since Jan. 1, 2011. That data mustbe collected with anFRM as defined in40 CPRPart 50, Appendix 

### 02or with an approved FEM for PMI0-2.5, andmustbe reported to AQS under parameter code 86101. CDPHE has no data underparameter code 86101 inAQS from any site. Ifthe paired Partisol2025 PM10 and PM2

.5samplers at La Casameetthe requirements of40 CPRPart 50, Appendix 

### 0, then historical PMI0-2.5 from La Casa should be calculated backto September 2012, when monitoring at La Casa began, and loaded into AQS.


### PM2.s FEM operation: Anotherrequirement for AMNPs, added to 40 CPR Part 58 as part ofthe 2013 PM2.s NAAQS Revision Rule,3 regards PM2.5 FEM monitors. Sections 58.10(b)(13) and 58.ll(e) were added to allow state and local monitoring organizations to documentpoorperformance ofPM2.5 FEM methods in comparisonto PM2.5 FRMs, and, through a request inthe AMNP, ask for EPA approval to exclude the FEM data from comparisons to the NAAQS for regulatory determinations.4
CDPHE operates five Thermo Scientific FDMS TEOMs, some or all ofwhich are designated as PM2.5 FEMs. While the equipmentmeets the specification ofthe FEM designation, CDPHEhas operated those monitors in a manner not identical to that specified in the FEM designation from EPA Office ofResearch and Development. CDPHE's operational modifications ofthe monitors predates the designation ofthe monitors as FEMs inJune of2009.
240 CPRPart 59, Appendix 0, Reference Method for the Determination ofCoarse Particulate Matter as PMI0-2

.5in the Atmosphere. 3 78 FR 3229-3230, 3234, and 3241-3244, January 15,2013, Final Rule, National Ambient Air Quality Standards for Particulate Matter. 4 78 FR 3230: "The revisedmonitoringrule, promulgatedtoday in conjunction with the PMNAAQS revision, includes, asproposed, language allowingmonitoringagencies to identifyPM2.5 FEMs thatare notprovidingdata of sufficient comparability to the FRMand, with EPA approval, to allow such data to be deemed ineligiblefor comparisons with the PM2

.sNAAQS"; 78 FR 3242: "Theproposal also providedthat the EPA RegionalAdministrator wouldbe responsiblefor approvingannual monitoring networkplans where agencies haveprovideda recommendation that certain PM2.5 FEMs be considered ineligible for comparison to the NAAQS." 3While we understand that CDPHE is not pursuing use ofthe FDMS TEOMs for PM2.s NAAQS comparison, in order to allow EPA Region 8 to approve CDPHE's use ofFDMS TEOMs solely for AQI purposes, EPA requests that FEMs used in the CDPHE network be identified in the 20 15 ANMP in accordance with Section 58.1O(b)(1.3), and that the detailed technical data of Section 58.11(e) be provided for the instruments as currently operated (perhaps as an appendix to the plan). In addition EPA requests a description ofthe current operation, noting deviations from the FEM operation, and the rationale that led to CDPHE to modify the operation. With this data, EPA could then approve CDPHE's current practices.


### Items to be addressed in 2015 AMNP: Three minor discrepancies were noted in the EPA review ofthe 2014 AMNP. First, Page 22 defines NAAQS exceedances in the same manner as 40 CFR Section 50.1(1), and page 28 says "there were no PM2.s exceedances recorded in the Western Slope region [in 2013]. The maximum 24-hour concentration at Powell42.2 

### )lglm\ [sic] and the annual average was 8.8 ug/m3

, though the average did not satisfy summary criteria." The 42.2 )lg/m3 value, and 3 others in 2013 at the Powell station were all exceedances ofthe 24-hour PM2.s NAAQS, contrary to the statement that there were no exceedances. Second, page 18 ofthe 2014 AMNP discusses the DenverMetropolitan Statistical Area (MSA) and Primary Metropolitan Statistical Area (PMSA), and the number ofMSAs in CDPHE. 40 CFR Part 58 uses the CBSAs and Combined Statistical Areas (CSAs) defined by the Office ofManagement and Budget (OMB) to define monitoring requirements. The term MSA is still used by OMB, but PMSA is an obsolete term and definitions ofPMSAs are no longer available from OMB. In addition, with new CBSA definitions from OMB in 2013, Colorado nowhas 7 MSAs, not the 6listed in the 2014 AMNP, and the Denver CBSA (or MSA) consists ofthe counties listed in the 2014 AMNP (Adams, Arapahoe, Broomfield, Denver, Douglas, and Jefferson), plus Gilpin, Clear Creek, Park and Elbert counties. We recommend that CDPHE review the new CBSA and CSA definitions from OMB and assess whether the existing and planned CDPHE monitoring network continues to meet the Part 58 requirements given those new definitions. EPA Region 8 staffprovided Network Assessment training, including this consideration, at the 2014 National Air Monitoring Conference in Atlanta, with the training material available at http://www.epa
.gov/ttnamti1/fi.les/20 14conference/monn@ayton

.pdf Third, page 29 ofthe plan says "The APCD does not collect orreport PM2.s FEM data." GRIMM FEM PM2.s data has been collected and reported to AQS by CDPHE since April of2013. For the 2015 AMNP and Network Assessment, we recommend that CDPHE review these items and update the information as appropriate.


### S02 Data Requirements Rule considerations: Finally, in 2015, the second five-year Network Assessment specified by 40 CFR 50.1O(d) will be due. A few things you may want to consider during this assessment are the potential implications ofthe proposed S02 DataRequirements Rule (http://www.gpo.gov/fdsys/pkg/FR-2014-05-13/pdf/2014- 09458.pdf) and consent decree approved by the U. S. District Court for the Northern District of California onMarch 2, 2015, and which I forwarded to Will Allison by e-mail onthat date.
The Rule proposal includes several possible threshold options for point sources, which would require monitoring or modeling, including EPA's preferred option of: 41) Actual emissions over 2,000 tons/yr; and 2) 1,000 tons/yr in cities over 1,000,000 population.
Iffinalized as proposed, the Rule would require monitoring or modeling data for point sources over these thresholds to inform future designation decisions. By January 15, 2016 states must identify the sources above these thresholds and determine whether modeling or monitoring (at each source) will be used to evaluate areaNAAQS compliance. For sources states choose to characterize by modeling, modeling protocols would be due to the Regional Office at that time as well. For sources states choose to characterize with monitoring data, required siting information about monitoring stations would be due to Regional Office by July 1, 2016.
Under the terms ofthe final consent decree, EPA will designate areas that have existing monitored NAAQS violations, areas that have sources greater than 16,000 tons ofS02 emitted in 2012, and areas that have sources emitting greater than 2,600 tons and an annual average S02 emission rate of0.45 lbs S02/MMBtuor greater (2012 data) within 16 months ofthe consent decree approval on March 2, 2015. EPA will then designate the remainder ofthe country by December 31 , 2017 unless monitoring to characterize a point source has begun in an area by January 1, 2017. Areas with newly installed source monitors (by January 1, 2017 or sooner) would be designated in 2020

. The combined impact ofthe Final Rule, to be published sometime in 2015, and the consent decree, will leave little time for decisions, monitoring network planning, and potential collaboration with sources. Therefore, including potential S02 designations monitoring in the 2015 network assessment might give states an opportunity to get ahead on the planning, while looking at non-binding options prior to the 2016 deadlines.

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