Tiller penalized for air-quality violations in North Branch

Company proposing mine in Scandia hit with fine


The Minnesota Pollution Control Agency (MPCA) has reached an agreement with Tiller Corporation, a sand mining and processing company headquartered in Maple Grove, to resolve air-quality violations at the company’s sand-processing facility in North Branch.

Tiller is the applicant for the Zavoral sand and gravel mine in Scandia.

The agreement covers the company’s failure to obtain required air-quality permits before starting construction of the North Branch facility in late 2011. Tiller has not yet begun operating the facility,but starting construction without permits is a violation of state and federal air-quality laws.

Tiller operates a sand mine in western Wisconsin and sought to build an industrial facility for processing and shipping sand in North Branch, Minn. Because the facility has the potential for air emissions above state and federal thresholds, the company was required to apply to the MPCA.

A permit application in February of 2012 was rejected because the potential emissions triggered requirements for an individual permit under the federal Clean Air Act.

The company applied for an individual permit in April of 2012. The MPCA expects to issue the permit soon; until then, the company may not operate the facility.

Tiller will pay a civil penalty of $5,000 and will monitor the air at the site for two years, testing for silica particle emissions of three sizes: 10 microns or less; 4 microns or less, and 2.5 microns or less.

The data will help the MPCA learn more about the concentrations of silica particles in the air near sand-processing facilities.