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Information on Ash Grove Cement Plant and Quarry, Montana City


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Tremoline crystals
Tremolite crystals at the contact between carbonate and a quartz pod in
magnesium-rich marble.

Tremoline crystals
Tremolite crystals in
carbonate rock.

Ash Grove Vicinity Map
Ash Grove Vicinity Map is a map with basic notes on what is in the vicinity of the Ash Grove plant and its haul route from the Clark Gulch Quarry.

In mid-March, the Ash Grove Cement Company notified the workers at its Montana City plant and Clark Gulch Quarry that the company was conducting an asbestos investigation at the facility, and that workers should not report to work until further notice. This was a voluntary action on the part of the company, and was not prompted by any directive either from the US Mine Safety and Health Administration (MSHA) or the Montana Department of Environmental Quality (DEQ).

In the wake of that public announcement, there have been numerous meetings, conference calls and visits to take samples by MSHA, DEQ, and Ash Grove. These efforts have been aimed at understanding where the mineral tremolite occurs at the quarry; determining whether or not asbestos is or is not present at the quarry, the plant, and the roads between those facilities; and - if asbestos is present - ensuring that no asbestos standard or threshold relating to protection of human health will be exceeded.

Sampling Results

This TABLE summarizes the numerous samples of bulk rock, bulk product, dust, air, soil, and quarry floor mud that have been taken and analyzed by four different laboratories. While the various sample sets are not always exactly consistent with each other, the great majority of samples detected no asbestos. With the exception of one particular rock, the few samples which did detect asbestos found it at levels that are well below the EPA (Environmental Protection Agency) threshold for classification of
a material as asbestos-containing material.

With regard to the EPA threshold, material that contains 1% or more asbestos is considered to be asbestos containing material. In the quarry, the samples that yielded
the highest asbestos concentration were taken in the northwest portion of the pit. The only sample that exceeded the EPA threshold for asbestos, and only by visual estimate under a microscope, was taken in this location. No other sample exceeded this threshold, and most samples were well below it. In addition, sampling results from haul road dust and soil samples near the Montana City School did not detect the presence of asbestos. Samples of dust from the flue at the plant did not detect any asbestos. Ninety percent of dust samples within the plant did not detect asbestos, and of the 10% of samples that were positive, the asbestos level was well below the threshold.

Is Ash Grove in violation of its permit?

No, Ash Grove is not in violation of its mining permit. Given the sampling and testing results, including the fact that no asbestos deposition has been detected off the mine site, and Ash Grove's plan for modification of the permit, there is no basis to find an imminent threat to the public health. The DEQ therefore does not at this time have a basis or the authority to suspend Operating Permit 00003.

Current Situation and Future Actions

On April 13, Ash Grove began limited maintenance operation at the plant, and workers are equipped with personal air sampling pumps. Special housekeeping activities to clean up areas of the plant where tremolite asbestos was found began April 27 simultaneously with start-up of routine production activities. The company has prepared a “Task-Specific Worker Protection Plan” that details a required level of personal protective equipment, industrial hygiene sampling and ambient air quality monitoring. Employees are also receiving “Tremolite Awareness Task Training” upon their return to work. The plans and training materials have been shared with the DEQ and MSHA.

MSHA will enforce the indoor ambient air standards of 1/10th of an asbestos fiber per cubic centimeter of air over an 8-hour period and 1 fiber per cubic centimeter of air over a 30-minute period. As part of its enforcement activity, MSHA also will require periodic monitoring of air within the plant through use of personal sampling pumps. This monitoring method is reliable in detecting generation of airborne asbestos.

If the results of future monitoring or future rock samples indicate the need for ambient air monitoring in the vicinity of the plant, the DEQ will require installation and operation of outdoor air quality monitors. The DEQ is not requiring monitoring of stack emissions at the plant because the kiln operates at a temperature that should destroy any asbestos fibers and because the results of testing on the flue dust indicate that stack emissions contain no asbestos. The DEQ will require periodic flue dust monitoring in the future to ensure that emissions remain free of asbestos.

With regard to the operations at the Clark Gulch Quarry, it is the DEQ's understanding that Ash Grove is reviewing the results of this geologic sampling and testing. Before it resumes operation in the quarry, it will, in consultation with DEQ and MSHA, prepare a plan to ensure that any future operations will be carried out in a manner that will avoid areas with elevated amounts of asbestiform minerals. DEQ will work with Ash Grove and MSHA to review the results and devise mine plan amendments that will ensure that asbestiform minerals are avoided. Once this plan is complete, the company’s Operating Permit No. 00003 will be amended pursuant to 82-4-337(3) to include the plan in the permit.