The proposed Rock Crushing Quarry will release Crystalline Silica into OUR AIR!

Michael Clark was the mine safety engineer at Huber for years. He is extremely well versed in not only our area and it's geology but in the dust/safety issues. He is a geologist by trade.

From: Michael Clark

Good morning,
Notes on the proposed mine:
• Blasting and open-pit operations are not likely to affect groundwater
Noise: will increase in the area, will have an environmental effect that increases above background such that neighbors will know the mine in present. Background noise will change to include mechanical sounds (crushers, conveyor belts, front-end loaders, dozers, haul trucks) above what had been peaceful country sounds.
Traffic: will increase due to OTR (over-the-road) trucks entering and exiting the highway, workers coming and going.
Air: increase in fugitive dusts due to mining and crushing activities. ,Activities that will increase fugitive dusts: blasting; vehicles on haul roads; maintaining rock stock piles (loaders piling gravel onto and taking gravel from); wind blowing across surfaces that used to be covered with vegetation such as haul roads, travel roads, open ground (benches) in the mine; crushing operations. The mine should have control measures in place for these activities, such as applying water (possibly with dust-suppression additives) to haul roads and bag-houses for crushing operations. In spite of control measures, there will be an amount of fugitive dust generated that escapes due to lack of perfect efficiencies of control measures, periodic failure of control measures.
• The fugitive dust will consist primarily of calcium carbonate and a smaller amount (on the order of 5%) of crystalline silica. The calcium carbonate obviously is the limestone. The crystalline silica will derive from millimeter-scale laminae within the limestone, thicker (up to typically an inch or so) discontinuous layers, smaller and larger nodules (that the Native Americans used to quarry for arrowheads). The calcium carbonate is classified as nuisance dust but does have a threshold limit value for health exposure purposes. The crystalline silica is classified as a known carcinogenic material and has a lower threshold limit value than the calcium carbonate. I don't recall what those TLVs are at the moment, but should be readily available in appropriate literature.
• In order to secure the permit, the mining should have completed air dispersion modeling due to concerns over fugitive dusts. The modeling should have been required especially given proximity to the medical facility. Verify modeling parameters and extent of dust plumes. Concerns can be raised over the impacts of fugitive dusts on the health of neighbors and especially the medical facility.
Hope this helps in your inquiries!

Michael Clark
Silt, CO