11011 CODY

OVERLAND PARK, KS 66210 

PHONE 913 / 451-8900 FAX 913 /451-1686 

CURTIS D. LESSLIE, PE 

VICE PRESIDENT, ENVIRONMENTAL AFFAIRS WRITER’S DIRECT LINE – 913/319-6065 

JULY 26, 2010 

VIA ELECTRONIC MAIL

Mr. Peter Tsirigotis 

Director, Sector Policies and Programs Division 

U.S. EPA, Emission Standards Division 

Mail Code: D205-01 

Research Triangle Park, NC 27711 

Re: Regulation of Portland Cement Kiln Mercury Emissions Under 40 CFR 63, 

Subpart LLL (Portland Cement MACT) 

Dear Mr. Tsirigotis: 

This letter is to update the Environmental Protection Agency (EPA) regarding Ash 

Grove’s efforts to lead the nation in the control of mercury from cement kilns. As you 

know, over much of 2006 and 2007, Ash Grove worked with a large group of 

stakeholders, including EPA, the Oregon Department of Environmental Quality, various 

tribes, medical professionals, engineers and environmental groups to gain consensus 

around the installation of new mercury controls for Ash Grove’s Durkee, Oregon plant. 

These stakeholders concurred that the new system envisioned for Durkee would set a new 

standard for mercury control. However, because nothing like it had even been 

permanently installed on a cement kiln, there was concern as to whether the control could 

live up to expectations. Since the group reached its conclusions, Ash Grove has spent 

two years and approximately $20 million to bring this design to reality. This state of the 

art mercury control system recently commenced operation and Ash Grove is submitting 

this letter to provide you with actual performance data from the first weeks of operation. 

As you will see, the system is exceeding the upper range of expectations and provides 

new data supporting the establishment of a subcategory for kilns, such as the Durkee kiln, 

that employ such advanced control technology. 

Background

Ash Grove Cement Company (Ash Grove) is an American owned business headquartered 

in Overland Park, Kansas. Ash Grove is the fifth largest cement manufacturer in the 

United States with cement plants in nine states across the country. A pioneer of the 
Mr. Peter Tsirigotis 

July 26, 2010 

Page 2 

limestone and cement industries, the Company was incorporated in Missouri in 1882 and 

has been majority owned and controlled by the Sunderland family since 1913. The eight 

cement plants operating in the Ash Grove system are some of the most efficient and best 

maintained in the country and have an annual production capacity of more than 8.0 

million tons of cement. The quality portland and masonry cements produced at these 

plants are used in the construction of highways, bridges, commercial and industrial 

complexes, residential homes, and a myriad of other structures. 

One of Ash Grove’s cement plants is located in Durkee, Oregon. The Durkee plant 

utilizes limestone and other materials quarried on site to make portland cement. The 

plant typically employs 116 persons including persons represented by 6 trade unions. 

With an annual payroll of $9 million and an operating budget in excess of $40 million, 

the Ash Grove Durkee plant is an important part of the economy in an economically 

depressed part of the state of Oregon. The unemployment rate in Baker County is 

currently 11.7% (May 2010 value). Unemployment in the counties immediately 

surrounding the plant is as high as 21.8% (Adams County, ID). 

Ash Grove’s Durkee plant, like most cement plants, relies on limestone quarried from a 

collocated quarry. The limestone from this quarry has elevated levels of naturally 

occurring mercury. Given the magnitude of the amount of raw material used, it is 

technically and economically infeasible to import raw materials from an off-site quarry. 

In late 2006 Ash Grove voluntarily performed extensive testing to better understand the 

nature and magnitude of its mercury emissions. This constituted some of the most 

advanced and comprehensive mercury stack and raw material testing ever performed at a 

cement plant. Ash Grove engaged national experts to perform multiple different types of 

tests using a variety of test methods so as to increase the company’s understanding of the 

quantity and type of mercury emitted from the plant. The stack testing indicated that the 

vast majority of the mercury was either oxidized mercury or elemental mercury, with 

elemental mercury making up as much as 70 percent of the total. 

With the emissions testing data in hand, Ash Grove performed a human health risk 

assessment to ensure that its uncontrolled emissions do not pose an unacceptable risk to 

the community. Relying on a nationally recognized mercury risk assessor, the company 

commissioned a complex risk analysis consistent with the requirements under the 

Hazardous Waste Combustor NESHAP. This risk assessment demonstrated that the 

plant’s uncontrolled mercury emissions do not pose an unacceptable health risk to the 

surrounding community. 

Although the risk assessment did not indicate that an issue existed, Ash Grove voluntarily 

decided to develop mercury emission controls for its Durkee plant. Ash Grove knew that 

no cement plant in the country had installed controls for the purpose of reducing mercury 

emissions. Five kilns in the country have wet scrubbers to control sulfur dioxide 

emissions and these controls are believed to provide a moderate level of mercury control. 

However, scrubbers (which consume millions of gallons of water per year) are not a 
Mr. Peter Tsirigotis 

July 26, 2010 

Page 3 

practical control technology in the arid western U.S, where water is scarce. Ash Grove 

also learned that wet scrubbers only control oxidized mercury as elemental mercury is not 

water soluble. This was particularly important where Ash Grove’s data indicate that a 

substantial percentage of the mercury in its exhaust is elemental mercury and so not 

amenable to control by a wet scrubber. Therefore, Ash Grove realized that it was going 

to have to develop a means of controlling mercury that was previously unknown in the 

industry. 

Ash Grove engaged the experts at EERC, a research center associated with the University 

of North Dakota that had extensive experience developing mercury control and 

monitoring techniques in the electrical generation sector. Armed with the stack test data, 

the EERC researchers proposed the use of an activated carbon injection (“ACI”) system 

to control mercury emissions. Ash Grove invested over $1 million to have EERC 

temporarily install a pilot ACI system at the Durkee plant. EERC was at the plant 

installing and operating the pilot system for over six weeks. Based on this in situ study 

EERC predicted that if the performance of a full scale system matched that of the pilot 

system, Ash Grove could reduce mercury emissions by approximately 75 percent on an 

annual average basis. 

Although Ash Grove believed that the EERC study had developed the optimum system 

design, the company conducted a peer review of EERC’s work with a broad array of 

stakeholders. Through a partnership with residents, environmental groups, Tribes, 

medical professionals, engineers and the state environmental and health agencies, Ash 

Grove went through a long and public process to determine the best means of addressing 

mercury emissions. What ultimately was approved by this diverse team was the 

installation of an activated carbon injection system with a recirculation loop and mercury 

recovery. These controls were anticipated to remove at least 75 percent of the mercury in 

the Durkee plant exhaust. However, Ash Grove committed to strive to get as close as 

possible to removing 85 percent of the mercury in its emissions. This level of mercury 

control had previously been considered unattainable for a cement kiln. We are 

submitting this letter to inform you that the initial results from operating the mercury 

control system indicate that we are capable of achieving at least the 85 percent mercury 

removal that the state and the stakeholders asked us to strive to achieve. 

Emissions Control Success 

The Durkee mercury controls have only been completed a short time and are still in the 

initial stages of shakedown. As a result, Ash Grove does not yet know the maximum 

long term control efficiency that can be achieved by operating the system. However, we 

have had two approximately one week runs of the control system. During each of those 

two periods, activated carbon was added to the control system at the start of the run 

period. Mercury levels in the exhaust gas entering the control system and mercury in the 

exhaust gas leaving the control system was sampled and measured for the entire time 

period. During the first run period, the activated carbon was added to the system partway 
Mr. Peter Tsirigotis 

July 26, 2010 

Page 4 

through the first day and removed from the system partway through the eighth day. No 

recycling of carbon was attempted thus providing good information regarding the 

carrying capacity of the carbon. The average removal efficiency during those intervening 

6 days was 92.8 percent. During the second run period, the activated carbon was added 

to the system late in the first day and removed from the system partway through the 

twelfth day. The amount of carbon used in the second run (980 pounds) was 

approximately half the amount of carbon used in the first run (2,000 pounds). In the 

second run, the average mercury removal efficiency during the first 6 full days of 

operation was 82.6 percent. Starting on the seventh day the control efficiency dropped by 

approximately half indicating that the carbon was becoming saturated. By the eleventh 

day, the carbon was adsorbing very little mercury. The raw data for these time periods is 

included as an attachment to this letter. The kiln is currently down for scheduled 

maintenance and so additional control data cannot be generated until the kiln starts back 

up. 

Based on these preliminary results, Ash Grove believes that the Durkee mercury control 

system has the clear potential to meet the upper end of the control effectiveness range 

identified for the plant, i.e., removal of 85 percent of the mercury in its emissions. We 

wanted to share these data with you so that you could take them into account in the 

finalization of the rule. Although we have not had the opportunity to run the control 

system for months and develop a full understanding of the variability across operating 

conditions and seasons, we believe that it is safe to say that we have demonstrated in 

practice that between 75 percent and 85 percent control of mercury can be achieved. We 

also believe that once we complete the installation of equipment to allow for the removal 

of some main baghouse dust for use in our cement mills (“dust shuttling”) that we can 

ultimately reach a goal of 90% control.

Subcategorization of Outlier Kilns

We believe that this new evidence is of great importance as you finalize the Portland 

Cement NESHAP. With these data in hand there is now a reasonable basis under the 

Clean Air Act to establish a separate subcategory for those sources with high levels of 

mercury in their on-site raw materials. Similarly, there is now a basis for a beyond the 

floor determination that will result in previously inconceivable levels of mercury control. 

Therefore, we are providing these data to you so as to support a decision to subcategorize 

based on the type of facility (i.e., a cement plant collocated with a quarry containing 

materials with high levels of naturally occurring mercury) and to support your 

determination to go beyond the floor and require that sources in this subcategory employ 

the now proven control technology in operation at the Durkee kiln. Absent such an 

outcome from the regulatory process, Ash Grove will likely be forced to close the Durkee 

plant and dismantle the controls currently in place at the plant. It would be a perverse 

outcome if the best controlled plant in the country was shut down by EPA’s standards, 

thereby putting over 100 people out of work and decimating an already economically 

challenged part of the country. 
Mr. Peter Tsirigotis 

July 26, 2010 

Page 5 

Conclusions

Ash Grove’s Durkee plant is an area source that voluntarily installed mercury controls 

that have redefined the state of the art for cement kilns. These controls are operational 

three years in advance of anticipated EPA requirements and the initial data demonstrate 

that they are capable of removing at least 75 percent of the mercury from the kiln 

emissions and likely will be able to meet or exceed the upper end goal of 85 percent 

removal. Notwithstanding an initial investment of approximately $20 million in the 

controls and substantial annual operating expense, the Durkee plant will not be able to 

comply with a PC MACT emission standard equal to the average emission rate of the 12 

percent of the cement plants utilizing limestone with the lowest mercury content. If EPA 

does not subcategorize in order to recognize the unique attributes of plants such as the 

Durkee plant, then the Durkee plant will likely have to shut down and the controls go 

unused. This outcome is contrary to both the Clean Air Act and the statement in the D.C. 

Circuit’s Brick MACT decision that “one legitimate basis for creating additional 

subcategories must be the interest in keeping the relation between ‘achieved’ and 

‘achievable’ in accord with common sense and the reasonable meaning of the statute.” 

EPA can keep the relation between “achieved” and “achievable” in accord with common 

sense and the reasonable meaning of the statute by establishing a subcategory for the high 

mercury limestone sources and requiring that they employ the now proven state of the art 

controls in use at the Durkee plant. 

Thank you for your consideration of this information. 

Sincerely, 

Curtis D. Lesslie, P.E. 

Vice President, Environmental Affairs 

Ash Grove Cement Company 

cc: Steve Silverman 

 Keith Barnett 
30405060708090

100

% Hg Emission Reduction

Durkee Plant - Pulverized Activated Carbon Injectio

Saturated 

PAC Removed

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PAC Injected LBS % HG Reduction
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Run Hours and % Hg Removal

Durkee Plant - Pulverized Activated Carbon Injection

Kiln Status HRS Run RM Status HRS Run % HG Reduction PAC Injec