Three homes were evacuated on Vedder Mountain Road on Saturday, following a landslide at the crest of the mountain above.
The landslide happened at 10 a.m., and was noticed by people walking on trails in the area as well as local residents. Nobody was injured and no private property has been reported damaged.
But it has kicked off an investigation by the Ministry of Energy and Mines, due to the close proximity of blasting at the rock quarry in very close proximity to the landslide sit.
The whole incident shook the nerves of residents at the base of the mountain who were evacuated. At least one of them has suggested the landslide was created by blasting at the rock quarry.
Scott Gouldsborough posted on Facebook that he and his wife were among the evacuees, and that he witnessed the landslide.
"At 10 a.m. Saturday morning my house shook from yet another blast from the rock quarry on top of the mountain," he wrote on Sunday. "This time it was loud and shook the house."
He said he looked up and saw "huge trees collapsing and could hear rocks coming down." He grabbed his wife and dogs and left.
The rock quarry is owned by Western Explosives, who confirmed through an emailed news release that they did a controlled blast at 9:55 a.m.
However, the company's president Bryan Kirkness, says there were other factors at play, including weather and even a 4 magnitude earthquake on Vancouver Island that could have contributed. Still, he has suspended blasting at the site indefinitely.
"This slide was not caused by blasted rock overloading the dirt slope," Kirkness said in the release. "The blasted rock was contained within a small area in and around the blast zone, as evidenced by the pictures taken by media and published. Our seismograph on site recorded minimal vibrations at 200 meters away from the blast. It appears ground conditions were unstable from the freezing/thawing and saturated ground. On the north slope ground conditions for unthawing are significantly slower than elsewhere. These conditions can potentially make soils become unstable and potentially sensitive to vibration. Indeed, perhaps the earthquake this morning had an effect of adding more sensitivity to ground conditions, we just do not know. What we do know is that the soils slid, without loading from blasted rock, right down to bedrock. We note that there have several slides in the Chilliwack area in the last few days due to conditions, regardless of any potential blasting effects."
He said the blasting was being done to provincial standards.
"All Ministry of Mines mandated mining blasting procedures and precautions were employed to conduct the blast," he said. "Immediately following the blast a mud slide was triggered down the north slope. Western Explosives personnel, City of Chilliwack personnel, and a Geotechnical Engineer were mobilized. Immediate works, supervised by all parties, were carried out by the quarry staff to stabilize any loose rock as a result of the blast. This was completed by around 14:00 Saturday."
The City immediately sent out a work crew, and a geotechnical assessment began.
Chilliwack Mayor Sharon Gaetz said that nobody was in any immediate danger.
"They're all safe, that's the good thing," she told The Progress. On Monday, however, one home was still unsafe to re-enter.
She said the city heard about the landslide at about 10 a.m. that morning and moved quickly to evacuate the homes below.
"We got news there had been a landslide above Vedder Mountain Road, and so the fire department went in as a precaution. The three families, they're all out. But there are three boulders sitting at the top that are in a precarious position. We immediately called a geotechnical professional to determine what is going on at the of the ledge."
She said they are hoping to learn what caused the rocks to come loose.
"We've had a huge weather event, and then a big thaw and we've heard there was also blasting in the area," she said. The City has notified the Ministry of Energy of Mines that there was a blast at the same time as the landslide. It would be that ministry that would conduct an investigation, city staff said.
Chief Inspector of Mines Al Hoffman responded to questions by The Progress on Tuesday morning. He said the ministry "take these matters very seriously."
"I understand that the people living in two of the residences are now back in their homes. However, the closest resident to the slide has to stay in a hotel for a couple of days," he said. While the cause has not been confirmed, he added that the geotechnical assessment is complete and the engineer found that the slope is now stable. The engineer also is recommending that a protective berm be constructed above the residences.
The investigation is not yet complete, though.
"I am sending Ministry of Energy and Mines staff to investigate," Hoffman said.
Kirkness thanked the City of Chilliwack senior staff for their "timely response and their abundance of caution in protecting public safety."
Western Explosives Ltd has suspended all blasting on the north side of the quarry indefinitely, he added.
"In our 15 years of operation at this site this is the first incident of a slide on the north slope. We wish to assure the public that our Geotechnical Engineer is engaged and will focus on this incident to ensure that the best and current information on geotechnical safety presented to us."