New conditions added at Zavoral
The Scandia council approved operating permits for three sand and gravel mines on Feb. 18.
The Zavoral mine reopened in 2013 after a lengthy environmental review, with opposition from the St. Croix River Association, the National Park Service and residents. Monitoring was required for noise, traffic, and air and water quality.
Sand and gravel from the mine is trucked to Tiller Corporation’s other mine in Scandia. No washing, crushing or other processing is done at the Zavoral site.
In September, vegetation was cleared. A right-turn lane into the mine was built in October. Mining began in November, with 83,500 tons of Class C add-rock hauled out in 3,620 truckloads.
Most conditions were met. The excavation depth is well above the ground water, and the amount of water used is well under the limit. No frac sand mining occurred. No volatile organic compounds were detected, and erosion control is in place.
Because of the rocky soil, Tiller was unable to transplant existing white pines with a tree spade as planned. Trees were being lost as the workers attempted to dig, Tiller staff said, and the city requires 80 percent survival.
The goal was to move 100 trees to the north side to create a transition between a woodland and prairie, but only one tree was transplanted there. Another 24 were moved to the west side to provide a screen from TH-95.
Scandia resident Pam Arnold said the trees were to go on a specific site as part of reclamation and objected to the new placement.
“Tiller shouldn’t be allowed to make these decisions,” she said.
Tiller has proposed leaving the pines in place and bringing in bare-root, 18- to 24-inch white pines, which can be planted without removing vegetation and rocks. The National Park Service prefers balled-and-burlap trees at least 5 feet tall.
The issue will be resolved after snow melt, with a meeting on site.
Another change resulted from new information. Models predicted surface water would move from west to east at the mine. Monitoring has shown a southeast flow, meaning Middle Creek receives more than expected.
A new condition requires adding surface water monitoring equipment on Middle Creek, as recommended by the Washington County Conservation District.
Other changes were to add “weather permitting” to a water monitoring requirement and to monitor noise within six weeks, not three, after a mining phase starts.
Noise complaints have been made about back-up beepers, but this occurred when a subcontractor was removing vegetation. Tiller equipment cannot use beepers, but subcontractors do not have this restriction.
A traffic analysis concluded that the mine did not lower the level of service at the intersection of TH-97 and TH-95. Another analysis will be conducted at Lofton Avenue.
The number of truck trips for hauling Class C add-rock is limited to an average of 334 to 400 per day. But trucks hauling topsoil for reclamation are allowed 440 trips per day. That will continue.
Tiller consultant Kirsten Pauly of Sunde Engineering recommended reducing noise monitoring, but Mayor Randall Simonson refused.
“When this council approved the conditional use permit, we assured the community we’d take this seriously,” he said. “Monitoring has to stay.”
The other Tiller mine in Scandia, located between Manning Trail and Lofton Avenue, also received a 2014 permit.
This mine is allowed to go 50 feet deep into the groundwater and has now gone 15 to 20 feet.
For the Bracht Mine on 185th Street, mining has ended. Last year the company removed stockpiles, established final grades and placed topsoil.
This year the wash plant and landscape boulders will be removed and final seeding done.
All three 2014 annual operating permits were unanimously approved.