Quarry update and CRC report on Golder peer review

The future of the “hidden quarry” is back in discussion at Guelph-Eramosa Township but discussions can’t move forward until all studies are completed.

“The review is still ongoing with a number of studies still outstanding although anticipated shortly,” explained Liz Howson from MSH Planning Ltd, at the Feb. 17 Guelph-Eramosa council meeting. “Timing of the planning report is dependent on the submission of those studies and circulation for comment of those studies.”

James Dick Construction (JDCL) has been working to open a gravel pit and quarry called the “hidden quarry” on the north side of Highway 7 at the 6th Line, since March 2013.  

The construction company is seeking an aggregate licence from the Ministry of Natural Resources (MNR) as well as a zoning amendment from Guelph-Eramosa that will allow the company to proceed with the proposed pit.

In her verbal report, Howson said that while it is anticipated that many studies needed to put together the planning report will be coming in shortly, some studies cannot be completed until other outstanding reports are submitted. For example, both the haul route study and the agricultural impact study must be submitted and the implications considered before the economic impact study can be completed, Howson explained.

She said, at best guess, if all of the outstanding reports are submitted by the beginning of March, she hopes to have the planning report out in May or early June.

Council also heard from a delegation representing the Concerned Residents Coalition (CRC) that has been in opposition to the quarry since JDCL announced its plan almost two years ago.

Bill Hill, on behalf of the CRC, discussed his report regarding the Golder Associates  peer review of the blast impact analysis. Hill is from William Hill Mining Consultants Ltd.

He suggested that there were holes in both the study and the peer review that should have been addressed and one of which was that the “hidden quarry” was compared to other quarries and situations instead of being seen as its own entity.

Another factor Hill said needs to be considered is ‘fly rock’ – the portions of rock that detach during mining and can fly hundreds of metres away from the pit site hitting what is in their path.

“Now if you ejected fly rock in our area [at 200 to 300m] you’d hit 20 homes from the pit easily,” he explained.

“Not to consider fly rock in a report on blasting, let alone a peer review, is almost unthinkable in my opinion,” he said. “It’s almost like putting on your shoes and not tying your laces.”

Hill also said the geology of the proposed quarry also wasn’t considered in the report. He said there is karst at the quarry’s location, a sponge-like rock formation, often signaled through sinkholes, but in the blast report it notes that there is not “very much karst or karst of importance.”

“In light of this we have to look at where [the quarry is] sitting,” he explained. “Not more than 100/150m is a whole zone of karst weathering mapped by the Ontario Geological Survey.”

He also pointed out that there are several sinkholes around the property, a sure sign that karst is present.

In a previous report Hill explained that karst is dangerous in this situation because it could create major cavities underground that the drillers are unaware of, and when the explosives are put into the drill holes they could possibly spill into these spaces, creating a larger than expected and dangerous blast.

Another concern Hill had with the report is that there was little discussion about ground vibrations. He notes that the formula used for predicting ground vibrations is from the United States Geological Survey and is based on arbitrary numbers taken from a different pit and has been found to be inaccurate in the past. This is of concern to those living around the quarry but also for the wetlands and ecology of the proposed site.

Because the quarry is below water level, a clay and rock barrier will be made.

“In this case the barrier’s going to be holding water and 8m below is going to be the pit level,” Hill explained. “Now what happens is, as the shock waves get closer and closer to those barriers the shock waves are going to be so strong that the barrier is going to be ruptured…with all the wetland draining into the quarry.”

If the barrier is damaged it could mean the quarry will need to be de-watered, damaging the surrounding ecosystem.

Council received both delegations for information purposes.