A large part of Rockwood as well as residences to the south in Nassagaweya will feel vibrations from blasting and the vibrations will be strong in the southern neighbourhoods, Eramosa 6th and 7th lines, and the northern parts of Nassagaweya 5th and 6th lines. The water-logged karst rock that exists through much of this area is an excellent mediium for the transmission of vibration. It is important to recognize that JDCL’s predictions of blasting vibration levels are entirely theoretical even though this is a very complex issue that utlimately will become clear when blasting begins, and then we’re stuck with the consequences. Vibrations put all buildings within 1000 metres of the site at risk of structural damage, not to mention a number of 18th century heritage houses and barns which have been maintained by the current property owners.
This is a big unknown but it could. CRC’s analysis of projected blasting vibration shows that any structure within 1000 metres of the site will be at risk. There are two members of the CRC who moved here to get away from quarry operations. One member lived near the Acton quarry and their foundation develped a crack after an unusually strong blasting shock. The company refused to take responsibility. In addition the side road they lived on was closed several times to clear fly rock from blasting that did not go as planned. Another CRC member lived near the Guelph Dolime quarry. Their neighbourhood complaints to the Province were dismissed because the vibrations were “within Provincial limits.” They were concerned that damage would occur sooner or later and moved. Heritage homes with stone structures are especially vulnerable to damage from vibration, but even modern wood-construction homes will be affected. In other similar situations, foundation cracking and damage to above-grade walls and windows have been experienced. CRC is particularly concerned about the 11 heritage buildings (houses and barns) within 1000 metres where 18th century mortar is most prone to vibration risk.
Flyrock refers to the unintended ejection of rocks from blast holes due to fissures, cavities, or other weaknesses in the underground rock structure adjacent to the blast holes or faulty blast design. Flyrock ejected from the top of the blast holes, as opposed to the face of the excavation much of which will be under water, is the potential problem in the Hidden Quarry. Many jurisdications around the world require exclusion zones of 500 m for rock blasting operations, but here there are no standards meaning that the 19 houses, businesses, buildings and residents within the 500 metre radius are at risk, as well as cars, school and GO buses and other vehicular traffic along about a one and a half kilometre stretch of Provincial Highway 7, a busy commuter road in this area. “Wild flyrock” also can occur, with incidents of rock being thrown 1000 to 1200 m having been reported.
It is located at the corner of Highway 7 and 6th Line Eramosa, just east of Rockwood and west of Acton. It is only one kilometre from the southern neighbourhoods of Rockwood as the crow flies, and as little as 165 m from homes and buildings on Eramosa 6th and 7th Lines and those at the north end of Nassagaweya 5th line! Nearly half the population of Rockwood lives within 2 kilometers of the site.
In a gravel pit only surface gravel deposits are removed. They are usually only open for a few years. The top soil is preserved and after the gravel is removed the top soil is replaced for farming. A quarry strips away all the top soil and gravel down to bed rock then blasts into the bedrock to remove stone which is crushed and usually trucked away for a full range of construction use from roads to buildings. The Hidden Quarry proposes to blast 100 feet into the water table over a 60 acre area. It will operate for at least 20 years and maybe much longer, leaving two small lakes. The property will no longer be available for agriculture. It may also expand into neighbouring properties.