Air Expertise Colorado 

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September 23, 2013

Karin McGowan

Interim Executive Director

Colorado Department of Public Health and Environment

4300 Cherry Creek South Drive

Denver, CO 80246

VIA EMAIL TO KARIN.MCGOWAN@STATE.CO.US AND TO 

CDPHE.COMMENTSAPCD@STATE.CO.US

Re: Serious Violations of the New SO2 NAAQS by Martin Drake Electrical Generating Facility in 

Colorado Springs – Curtailment or Cease Operation Order is Necessary Immediately

Director McGowan:

The Martin Drake facility in Colorado Springs is a 278 MW coal-fired electrical generating station 

(CDPHE Permit Number 950PEP107) that was constructed in the 1960’s. More than 40 years following 

the passage of the Clean Air Act, the Martin Drake’s operating permit allows it to emit 14,400 tons per 

year of sulfur dioxide (SO2), with absolutely no constraints that limit the plant’s SO2 emissions to ensure

that its impacts are not injurious to human health. 

Since the advent of the Clean Air Act regulations of the 1970’s, US EPA has set maximum permissible 

ambient levels of pollutants called National Ambient Air Quality Standards (NAAQS). The levels are set 

to protect the health of any group of the population from exposure to pollutant levels that incur health 

effects. In 2010, US EPA set a new 1-hour NAAQS for SO2 to replace the then-current 24-hour and 

annual SO2 NAAQS. To determine the level of the new NAAQS, US EPA relied on a thorough 

compilation of epidemiological and medical observations on the known and potential health effects from 

SO2 exposure. This database shows the strong positive association between respiratory morbidity events 

(i.e., emergency room visits and hospitalizations) to the ambient SO2 concentrations to which the 

sufferers were exposed. 1 

Importantly for Colorado Springs, US EPA’s rationale in setting a new short-term standard in part 

stemmed from numerous epidemiological studies that show positive associations between exposure to 

ambient SO2 concentrations and respiratory symptoms in children (including emergency room visits 

and hospitalizations for all respiratory causes) - in areas where the previous NAAQS were met.2 The

association between exposure to short-term ambient SO2 concentrations and asthma symptoms, in areas 

where air quality monitors showed attainment for pre-2010 standards, extends to all age groups. 

This letter reports on ambient air quality modeling results that are derived using 1) US EPA-and CDPHErecommended procedures,

3

2) plant emission limits that are allowed by CDPHE, and 3) stack flow 

 

1

Primary National Ambient Air Quality Standard for Sulfur Dioxide; Final Rule, 40 CFR Parts 50, 53 and 58., 

Federal Register, June 22, 2010; p. 35526. 

2

Similarly, Colorado Springs met the pre-2010 24-hour and annual standards. 

3 US EPA’s “Guideline on Air Quality Models,” also published as Appendix W to 40 CFR Part 51. This analysis 

uses five years of meteorological data from Colorado Springs Municipal Airport (surface data) and Denver 

International Airport (closest upper air station), and geographic elevations from USGS data sources. 
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characteristics based on actual test results.

4 These AERMOD results show that the Martin Drake 

facility’s permit currently allows emissions that violate the SO2 NAAQS egregiously – i.e., by more 

than five times the maximum level of pollutants that US EPA deems safe to human health – frequently 

throughout the year, and over large populated sections of Colorado Springs. This situation, whereby 

the health of the residents of Colorado Springs is ignored and repudiated while the facility’s operations 

go untethered, must be corrected immediately. Figure 1 and Table 1 present these results.

 

 

4 Airtech Environmental Services, “Report on the Relative Accuracy Test Audits Conducted for Colorado Springs 

Utilities at the Martin Drake Power Plant, Units 5, 6 and 7,” for test dates between May 30 and June 6, 2013. These 

reports were relayed to Air Expertise Colorado through a Colorado Open Records Act request in September, 2013. 
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TABLE 1 - TEN WORST LOCATIONS FOR 1-HOUR ALLOWABLE IMPACTS OF SULFUR DIOXIDE 

BY MARTIN DRAKE FACILITY 

(MULTIPLE OTHER LOCATIONS OF EXCEEDANCES OCCUR AS INDICATED ON FIGURE 1)

1. 1147. ug/m3  5 times the NAAQS Area near Mesa Trail and Red Rock Canyon Trail

2 1030.  5 times the NAAQS West of El Pomar Road, near Starsmore Discovery Center

3 915.  4 times the NAAQS Area of Preserve Drive and Brantfeather Grove

4 831.  4 times the NAAQS Area of Broadmore Bluffs Drive

5 823.  4 times the NAAQS Area west of RioGrande Road and Cresta Road

6 788.  4 times the NAAQS Residential area west of El Pomar Road

7 777.  3 times the NAAQS Upper floors of downtown office towers in vicinity of 

Tejon and Colorado Streets. 

8 755.  3 times the NAAQS Area near Cheyenne Mountain High School

9 744.  3 times the NAAQS Area near Scorpio Circle and Scorpio Drive

10. 737.  3 times the NAAQS Area of Astro Drive and Virgo Drive

Notes: 1-hour impacts equal the 5-year average of the 4th highest 1-hour values calculated using daily maximum 1-

hour values. This means that there are multiple hourly occurrences of impacts in excess of the concentration level of 

the NAAQS. Addtionally, these results under-predict total exposure by a) not including background concentrations 

and b) not evaluating impacts at all elevated office buildings and other tall structures in the area. 

Air Quality Modeling Procedures 

The results reported on here derive from application of US EPA’s AERMOD model, with procedures that 

conform to the Guideline that is prescribed by federal law. The first release of AERMOD (in 2004) 

followed approximately a decade of research and development by air quality scientists and meteorologists 

(AERMOD was produced through a collaboration of US EPA and the American Meteorological Society). 

Subsequently, the version of AERMOD applied herein (v. 12345) includes additional improvements 

developed throughout the approximate-decade of application following the first version’s release. 

US EPA concluded5on the basis of multiple databases that compare model prediction by AERMOD to 

monitoring results for facilities with downwash characteristics (like this facility), that overall, the ratio

between the maximum predicted to maximum observed concentrations is 0.97 (i.e., the maximum 

predicted AERMOD concentration is approximately equal to the maximum observed concentration). In 

short, the AERMOD model performs very well in simulating actual air quality impacts of facilities like 

the Martin Drake. 

The next step of the modeling analysis of the Martin Drake facility should be the use of these AERMOD 

results to evaluate the costs of the health effects for Colorado Springs’ residents, and of the benefits of 

reducing pollutant levels from the Martin Drake facility. Such an evaluation is possible: the US EPA’s 

BenMAP program6uses a Geographic Information System that is linked to US Census Bureau 

population and demographic data, to estimate the health impacts and economic benefits that occur when 

populations experience changes in their exposure to air pollutants. Such an accounting of the full costs 

that Colorado Springs residents bear, from the health effects associated with exposure to Martin Drake’s 

emissions were disclosed, would likely show astounding results, and should be included in any evaluation 

of the Martin Drake’s viability.

 

5 Model Evaluation Paper, dated 2004, posted at US EPA’s Technology Transfer Network/Support Center for 

Regulatory Models.

6

http://www.epa.gov/air/benmap/.
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Air Quality Modeling Preferred over Monitoring by US EPA for Areas with Large Sources 

Unfortunately for the citizens of Colorado Springs, multiple statements by Colorado Springs Utilities

(CSU)7display ignorance of the citizen protections and mechanisms of the Clean Air Act regulations that 

apply to the Martin Drake’s emissions. As reported in January, 2013, CSU spokesman Dave Grossman 

stated that “ongoing local monitoring between 1988 and 2007 showed that sulfur dioxide levels were 

significantly lower than the EPA threshold.” Grossman neglects to mention that any monitoring that was 

discontinued in 2007 (as he states) could not have addressed compliance with a new standard that was not 

even proposed until 2010. 

In 2010, when US EPA promulgated the final rule of the new SO2 NAAQS, the agency devoted 

significant portions of the rule to establish that its preference is that air quality modeling is preferred over 

monitoring when evaluating pollutant levels in areas where large pollutant sources operate. US EPA 

states that “it is more appropriate and efficient to principally use modeling to assess compliance for 

medium to larger sources, and to rely more on monitoring for groups of smaller sources and sources not 

as conducive to modeling.”8

Yet, in January, 2013, CSU spokesman Grossman disparages another study9(after its results showed 

severe violations of health-based standards by Martin Drake emissions) because it applied exactly the 

methodology and procedures that US EPA prefers (“the sulfur dioxide study commissioned by the Sierra 

Club uses theoretical modeling only”). Grossman goes further in providing misleading information, by 

stating that “[t]he EPA has not yet published guidance on appropriate assumptions for this type of 

modeling,” despite the fact that in 2010, US EPA published, as a follow-up to the new NAAQS, the

“Guidance for 1-Hour SO2 NAAQS SIP Submissions.”

10

 This guidance stipulates the assumptions for 

exactly the type of modeling that was (and still is) CSU’s un-met duty to perform. These statements by 

CSU display a reckless neglect and lack of due diligence by the Board towards the air quality regulations 

and proceedings that bear directly on its duty to maintain safe operation of the Martin Drake facility. 

A Full Accounting of Impacts on Residents and Nearby Recreational Areas Must Occur Now

Timing is propitious for an immediate remedy to this situation, due to several factors. First, a very costly 

study of potential long-term operating scenarios (i.e., at a cost of approximately 1⁄2 million dollars) is 

being undertaken now, underwritten by the taxpayers of this municipally-owned facility.

11

 Distressingly, 

the scope of this costly study does not include assessment of any of the long-term scenarios’ operational 

compliance with NAAQS. It is not clear how the CSU’s Board intends to intelligently judge the legality 

and efficacy of long-term operation of the facility, when it lacks knowledge of whether or not future 

options emit pollutants that impact city residents at unhealthful levels. 

 

7

Spokesman Grossman also stated that “[i]n fact, the levels each year generally ranged from 12 PPB to 26 PPB, 

well below the new standard. The monitoring program was discontinued in 2007 because SO2 levels were 

consistently so far below EPA’s standard...” at http://csbj.com/2013/01/17/sierra-club-study-eyes-drake-plantsemissions//.

8

Primary National Ambient Air Quality Standard for Sulfur Dioxide; Final Rule, 40 CFR Parts 50, 53 and 58., 

Federal Register, June 22, 2010; p. 35570.

9

“Martin Drake Power Plant - Colorado Springs, Colorado - Sierra Club Evaluation of Compliance with 1-hour SO2 

NAAQS,” Report by Wingra Engineering, October 4, 2012, at http://content.sierraclub.org/coal/colorado/update/15-

jan-2013/release-martin-drake-so2-modeling-shows-violations-post-modifications.

10 “Guidance for 1-Hour SO2 NAAQS SIP Submissions,” see Appendix A - Modeling Guidance for Nonattainment 

Areas and Section 110(a)(1) Plans. http://www.epa.gov/airquality/sulfurdioxide/pdfs/DraftSO2Guidance_9-22-

11.pdf.

11 Study of Alternatives related to the Potential Decommissioning of the Martin Drake Power Plant, Awarded to 

HDR, with estimated time and material cost of $465,000. 
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Second, the citizens of Colorado Springs will soon be underwriting another very costly (a 120 million 

dollar project) to install an SO2 control system, again, with no assurance that the Martin Drake will 

operate in compliance with the NAAQS. In recent correspondence, CSU stated that there currently is 

no 1-hour SO2 emission rate guarantee to which the vendor will be constrained for operation at 

Martin Drake.12 Guarantees of emission rates in accordance with the time basis of NAAQS rates are 

standard procedure for control technology vendors, and such an emission guarantee should have been 

demanded by CSU as a condition of the SO2 control vendor’s contract. 

While levels of SO2 control on the order of 90% are reported for the planned technology, it is important 

to note that wet flue gas desulfurization techniques (like the planned system) often cool the flue gas. This 

cooling of flue gas occurs due to the evaporation of the injected wet slurry with which the sulfur in the 

flue gas reacts. 13 Unfortunately, this reduction in flue gas temperature also leads to a reduction in flue 

gas buoyancy, in part offsetting the reduction in SO2 at ground-based impacts of the plume in the vicinity 

of the plant. 

To iterate, a full demonstration of the plant’s current, as well as future, compliance with NAAQS is 

immediately necessary in order for the citizens of Colorado Springs (the purchasers of the very costly 

SO2 control system) to understand whether or not it will protect them from unhealthful levels of air 

pollution. This demonstration must take into account the:

1) proposed operating characteristics of the facility with the implementation of the SO2 control 

system, including any reduction in flue gas buoyancy;

2) all changed downwash characteristics due to new lime, limestone or reagent silos;

3) all pollutants and byproducts that the new control system may increase with it operation, 

including particulate matter emissions from the lime, limestone or reagent silos and within the 

flue gas.

This air quality analysis should also evaluate the detriment to visibility on all nearby recreational and 

scenic areas that may result for the current and future scenarios, due to the important contribution to the 

commerce of Colorado Springs that recreation and scenery represent. 

Essential Elements of the Facility’s Ambient Air Quality Compliance Demonstration

To iterate, full ambient air quality compliance demonstration of the facility’s current and future 

operations should proceed immediately. If these are to truly establish the maximum impacts of operation 

of this facility on Colorado Springs, these analyses must:

- Follow the procedures stipulated by US EPA within federal law (40 CFR Part 51, Guideline on 

Air Quality Models, i.e., the “Guideline”);

- Simulate impacts using five years of local and regional meteorological data, processed according 

to the Guideline;

- Calculate impacts for a full network of receptors that includes all elevated structures within a 10 

kilometer radius of the facility (i.e., receptors should be placed at the tops and all floors of 

downtown office towers);

 

12 Correspondence from John Butler of Colorado Springs Utilities to M. Barrett, August 28, 2013. Mr. Butler stated 

that he was relaying information from the environmental division of CSU that there is no guarantee for a 1-hour 

emission rate for the SO2 control system.

13 A portion of the water in the slurry is evaporated and the waste gas stream becomes saturated with water vapor. 

See US EPA’s Air Pollution Control Technology Fact Sheet, EPA-452/F-03-034, Flue Gas Desulfurization (FGD) -

Wet, Spray Dry, and Dry Scrubbers, at www.epa.gov/ttn/catc.
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- Include within he receptor network all locations where sensitive individuals (children, asthmatics, 

elderly) may reside, work or play, including hospitals and day care centers, within a 10 kilometer 

radius of the facility;

- Include, for particulate matter simulation (i.e., PM2.5 and PM10), wind-driven emissions from 

the coal pile and coal processes (coal crusher, graders, etc.) including emissions from open coal 

railcars that line the western fenceline;

- Include downwash characteristics that are determined using actual and future plant and equipment 

layout, including all additional structures associated with the SO2 control system. 

- Show how the maximum impacts from the facility’s emissions of toxic air pollutants compare to 

each pollutant’s recommended maximum level of exposure. 

The draft protocols for these modeling demonstrations should be released for public comment 

immediately. Upon development of final modeling protocols, results should be published within one 

month. Potential operational remedies for the facility to meet compliance of NAAQS should include:

- Immediate curtailment of emission limits through reduction in output;

- State and federal enforcement of the curtailed emission limits within a new operating permit or 

consent order;

- Installation of a wind fence around the perimeter of the coal pile (there is no apparent reason why 

such a simple best management practice has not already been implemented);

- Application of a surfactant to the coal pile to diminish wind-driven emissions.

Until operational limits for Martin Drake have been determined that comply with all NAAQS, and 

made enforceable through a permit, the plant should cease or immediately curtail its operation to

approximately 10% to 20% of output (to date, two independent air quality compliance analyses show that 

this scale of reduction is necessary to protect public health). Precedent exists for state intervention to 

protect the public from egregious conditions of air pollution exposure. In 2005, the Virginia Department 

of Environmental Quality, upon being informed of air quality modeling results showing similarly

egregious impacts in excess of NAAQS by another aged coal-fired electrical generating station located in 

a populated area, issued an order that the facility immediately reduce or shutdown its operation.14 

Potential New Source Review Environmental Liabilities should be Fully Disclosed

CSU may incorrectly assume that the Martin Drake facility has been “grandfathered”15 for 40+ years from 

the Clean Air Act program requirements. The Clean Air Act stipulates that owner/operators of major 

sources [Martin Drake is a major source] undergo implementation of control technology and a NAAQS 

air quality compliance demonstration when their source undergoes a physical modification – if that 

physical modification leads to annual emission increases that are “significant.” 16 Major physical 

components in a coal-fired electrical generating station include wall, floor and roof boiler tubes, 

 

14 Robert G. Burnley, Director, Virginia Department of Environmental Quality to Lisa D. Johnson, President, Mirant 

Potomac River, LLC, August 19, 2005. 

15 “Congress never intended to permanently exempt existing facilities from these requirements...existing plants that 

have been modified are subject to the Clean Air Act programs...the purpose of the modification rule is to ensure that 

control measures are undertaken when they are most effective, at the time of new or modified construction,” 

Opinion and Order, USA versus Ohio Edison, 2005. See description of settlement at 

http://www.epa.gov/compliance/resources/cases/civil/caa/ohioedison.html.

16 “New Source Review Workshop Manual, Prevention of Significant Deterioration and Nonattainment Area 

Permitting,” Draft, October, 1990, at http://www.epa.gov/NSR/ttnnsr01/gen/wkshpman.pdf.
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economizers, super-heaters, and re-heaters. In this operating environment, severe thermal cycling, harsh 

corrosion from exposure to caustic agents, and high velocity impaction from particles and flue gas often

cause these components to fail, degrading plant availability and performance. Conversely, replacement of 

these components can lead to increased plant heat rate, reliability and plant utilizations, and consequently 

emission increases that exceed significant levels. 

The 50+ year operation of the Martin Drake facility, in the absence of any modification or replacement of 

critical subsystems and parts, appears to defy the typical coal-fired power plant’s lifetime of 30 to 40 

years. For installations like the proposed SO2 control system, associated physical modifications and 

upgrades of ancillary components (like fans) are often necessary to accommodate its operation – these 

ancillary modifications often result in increased plant availability, output and performance –

increasing other regulated pollutants beyond significance levels. It is critical that all past physical 

modifications at the Martin Drake facility, and detailed plans for the future modifications to accommodate 

the SO2 control system, be fully disclosed for public review. Using these disclosures, in combination 

with time series of plant output that have are recorded by US EPA,17 public review can assess if past or 

future modifications lead to increased annual emissions, and consequently, if they trigger Clean Air Act 

New Source Review requirements. 

A New Source Review settlement in the future, potentially involving additional control technologies and 

penalties, would represent potential environmental liabilities that the citizens of Colorado Springs should 

fully understand when considering the long-term options of this plant. 

Summary of Requests 

In summary, I respectfully request that CDPHE instruct CSU to immediately: 

1) Curtail within an enforceable order, the hourly output of the Martin Drake facility to between 

10% to 20% of its rating;

2) Publish all of the SO2 control vendor’s test and operational data so that an air quality 

modeling demonstration of the proposed operational scenario can go forward;

3) Publish all historical data, documents, engineering drawings and specifications that describe 

every physical modification that has occurred at the Martin Drake;

4) Publish all documentation, specifications, and engineering drawings of modifications,

replacements or upgrades to the existing Martin Drake equipment that are planned to 

accommodate the new SO2 control system;

5) Designate an open ftp site where all of the above information can be posted. 

Thank you for your attention to this important issue. Upon your request, I will gladly post all of the 

AERMOD input and output files of this study to a designated ftp site for your review. 

Maureen Barrett, P.E.

Principal, Air Expertise Colorado

 

17 Data posted at www.epa.gov/airmarkets. These quarterly continuous emission monitoring system data can be 

reviewed to determine changes in plant output that have occurred and how the changes correlate to plant 

modifications. 
Air Expertise Colorado 

 Evergreen, CO

303.670.0515 

 mbarrett@airexpertisecolorado.com 

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cc:

Colorado Springs City Council (acting as Colorado Springs Utilities Board)

allcouncil@springsgov.com

Howard Cantor

Acting Regional Administrator

US EPA Region 8

R8eisc@epa.gov

Memorial Hospital Central and Memorial Hospital for Children

michelle.moy@uchealth.org

Bryce Carter, Sierra Club

Bryce.Carter@sierraclub.org

Anschutz Corporation

Owner, Manitou and Pikes Peak Railway 

info@cograilway.com

El Paso County Board of Health

healthinfo@elpasoco.com

Dr. K. Patrick McCaffery, President 

Pikes Peak Pediatric Society

info@pedassoccs.com

Colorado Springs Senior Center

info@csseniorcenter.com