Guelph-Eramosa councillor Doug Breen wants a single answer to conflicting engineering reports on whether a sponge-like rock formation, known as karst, exists on the site of a planned quarry in the township.
A Guelph-Eramosa citizens group attempting to halt the development of “the hidden quarry” focused its efforts on the potential hazards connected with the karsk formation and blasting planned by James Dick Construction.
The company is seeking an aggregate licence from the Ministry of Natural Resources (MNR) as well as a zoning amendment from the township that will allow the company to proceed with a pit that is expected to produce about 700,000 tonnes annually of sand, gravel and dolostone.
The quarry would cover about 25 hectares (61 acres) of the 39-hectare (100 acre) James Dick property at the northeast corner of 6th Line and Highway 7 and could operate for 20 years.
The company has already indicated the plan would be to undertake below-the-water-table blasting at the site, an proposal opposed by the Concerned Residents Coalition (CRC) whose members showed up in force at council’s March 17 meeting.
Members Michael Venhuis and Bill Hill disputed the findings of a Harden Environmental Services letter dated Sept. 5, 2013 that stated, “A karst environment is not present in the area proposed to be mined by the hidden quarry.”
Venhuis told council a karst environment at the quarry has already been acknowledged by township engineering firm Burnside and Associates and by the MNR.
Venhuis said blasting of the porous rock presents a danger of contamination of groundwater and also a problem with flying rock when the sponge-like formation fractures.
The CRC representatives contend more exploratory holes should be drilled on the site to determine the extent of the karst formation.
Venhuis said the MNR indicated study is needed to determine potential hazards connected to karst formation.
“No one formula exists for determining how hazardous a karst formation is, or may become,” a ministry statement presented by Venhuis said.
“The size, extent and severity of the hazards vary greatly from location to location. Identification of the hazards requires a thorough site-specific assessment.”
The CRC is calling for such an assessment of the hidden quarry site.
“We have two sets of eyes looking at the same results and coming out with two different conclusions,” Breen pointed out.
Council will be seeking clarification on the findings to determine whether the karst formation exists – and to what extent.
