12/13/2012 9:13:00 AM Over 100
by DENISE MARTIN
Tiller Sand & Aggregate company officials were reminded last week how hard it is to regain trust once others perceive you to be untrustworthy. About 100 people attended the air quality permit public hearing at the North Branch Library and many in the audience declared they doubt the state’s reliance on Tiller self-policing its emissions standards, or providing accurate data in reporting to regulators. Citizen Larry Nelson summed up the sentiment at the meeting, saying their company history “leaves a lot to be desired.” Tiller has asked the state pollution control agency to set emissions standards and issue an air quality permit in order to operate its new sand processing plant in North Branch. The public hearing December 4 was one of the required steps to write the permit. Public comment on the permit continues to be submitted to the PCA until Dec. 14.
The plant is almost operational; people were advised the company just needs to bring natural gas supply into the site and could start-up in a matter of weeks once permits are in place. Tiller’s Director of Land Use Affairs, Mike Caron stated that the company, “made an honest mistake” constructing the facility without the emissions permit approved. Caron said Tiller will pay the fine (an enforcement action is pending) and is also agreeing to install monitoring equipment beyond what the Minnesota Pollution Control Agency ordinarily requires. Steven Gorg, the PCA engineer who will be writing the permit, told the audience equipment and monitoring procedures being implemented at the North Branch sand processing plant are tops in the state. Some citizens weren’t feeling reassured. Under the preliminary terms of the air quality permit -- Gorg said Tiller could be allowed up to 89 tons per year as a maximum production of “respire-able” material. Gorg said the baghouse collects the fine dusty sand particles that remain after sifting, and contains them.
The various products and hydro-fracking application (in the Dakotas) that are customers of Tiller’s call for particles of a certain size. There are trained employees who use equipment that will sift and sort the sand and measure the clearness (opacity) of the air at the plant, as well as self-monitoring of air quality (equipment exhaust, etc). The vast majority of product at the North Branch plant will involve sand particles larger than PM100 (microns), which is the start of the size at which granules can be inhaled, Gorg explained. Smaller particles get contained in the baghouse. The audience was shown slides of the sand drying, sifting and bagging/loading stations that have the potential to run 20-hours-a-day at the Tiller plant. Silica sand arrives having already been “washed” elsewhere. Tiller will use up a stockpile at a pit, east of Harris in Sunrise Township, which holds 200,000 tons, said Caron. A pit in Wisconsin near Grantsburg is also a material source. Citizens, however, said by their calculations, based on the truckloads and traincar loads estimated in the permit-- Tiller could end up having to “contain” many tons of potentially airborne silica sand, on a regular basis. The permit estimates this by-product at one percent of the plant’s capacity. Audience members pointed out that when the plant is capable of 150 tons passing through every hour-- this one percent is significant. Officials reiterated the efficiency of mechanical systems Tiller will be using, and the closed nature of the new plant’s sand drying and sifting and loading/transport practices. Chutes can be lowered into trucks and railcars and the enclosed baghouse gets frequent shakedowns so product doesn’t build-up. Don Smith, also of the PCA, stressed that should there be issues later with fine sand coming off trucks, or with air clarity, or other concerns people can always contact PCA and the agency will work with local authorities to resolve issues. In related concerns: ~ Caron explained the dryer is fueled by natural gas, but the company will have back-up diesel fuel when gas demand spikes or when the energy company might interrupt service. ~ The product will be transported in covered trucks and/or rail cars.
Caron explained the sand arrives already washed. The moisture content is of great concern and Tiller wants to ensure a very dry product for customers so protecting it from rain, snow, etc. is important. ~ There will be no odor. Any noise expected is comparable to the ZinPro pellet plant nearby, which has similar burners in its rotary drum dryer equipment, Caron said. There’s no “crushing” of aggregate in North Branch. ~ Tiller plans no other use at this facility. There won’t be concrete or asphalt manufactured at this plant later on. The state permit could specifically require no use other than sand processing, and be more restrictive than North Branch land use standards, if people stress this as a concern when they submit their comments, Gorg explained. ~ Data is also collected on various parameters spelled out in the permit-- as far as chemical content of the air and what employees are exposed to personally, by the Mining Safety & Health Administration. It periodically provides “patches” that workers wear to absorb or collect vapors and particles, which are analyzed. Workers at the North Branch plant do not wear masks or any extraordinary protection.