Alberta Environment and Sustainable Resource Development closed a section of Exshaw Creek mid-June over concerns of public safety after boulders crashed down from the Lafarge quarry’s eastern ridge in the winter.
Ross Spence, director of the Southern Rockies Area for ESRD, signed the Notice of Closure June 13 to prevent harm to hikers in the area.
“It’s a 28-day temporary closure that allows us to deal with a potential public safety risk,” Jackie Ambler, an ESRD spokesperson said recently.
“Last winter there were reports that rocks were falling from upslope onto the trail from the Lafarge quarry and Lafarge as well the MD and representatives of the community association expressed concerns that could continue to happen this spring and summer, so we’re just temporarily closing the area so Lafarge can conduct a stability assessment,” Ambler said.
“There are a lot of rocks at the top of the slope just above tree line that could potentially fall. We’re getting Lafarge to test the stability to see the likelihood of that and see if we need to take further measures to see if the area is stable.”
One boulder broke through the old water pipe that runs along the creek from the dam and another is hanging sitting up slope from the creek.
Lafarge representative Michelle Gurney said Lafarge has hired Golder and Associates to do the slope stability study.
However, before that can begin, Lafarge has to provide new topographic images.
“Work can’t begin until we have new topographic images of the ridge. That’s the first step. Once we supply Golder and Associates with those images they can begin the study,” Gurney said. “All we are waiting for is a clear day. It has to be perfectly clear to be able to get those images and we’re just waiting for that to happen.”
Gurney added the large rocks did not move down the slope as a result of blasting. Rather it was a result of how the rocks were moved and placed following blasting.
“During material movement on the ridge, moving the rocks, creating new berms, some rocks went over the edge,” Gurney said.
“We recognized that as an opportunity to improve some of our processes. We’ve changed our rock placement procedures now to reduce the probability of rocks rolling off the ridge.”
ESRD will continue the closure for another 28-day period, if required, Ambler said.
“Public safety is our highest priority,” she said. “We are not going to open it before we know it is safe.”
The area affected by the closure is quite large as the Province closed the entire parcel of land that falls under Lafarge’s lease on the east side of the creek. Ambler said it made more sense to keep the closure to a single administrative unit, rather than shutting access to just a portion.
Anyone who enters the closed area faces the possibility of fines and charges under the Public Lands Administration Regulation, Ambler said.
The Exshaw Mountain trail has been identified as an alternate route around the closure.
For more information call the ESRD information centre at 310-ESRD.