Not Your Grandfathers Mining Industry, Nova Scotia, Canada

Aerotech Connector

It takes a lot of rock to build safe roads and highways! For example, almost half a million tonnes of rock aggregate went into building the new Aerotech Connector in Wellington.

The new five-kilometre highway connects Trunk 2 to Exit 5A of Highway 102 south of Enfield. The new route provides better access from Wellington to Aerotech Industrial Park and the Halifax Stanfield International Airport.

The project also includes five kilometres of multi-use trail, one pedestrian bridge crossing and four animal crossings.

Sub-grade construction required 315,000 tonnes of rockfill. It also used 136,000 tonnes of Type 2 gravel, which is smaller and has a higher percentage of fines (aka dust) in it from the rock crushing process.

Type 1 and Type 2 gravel is often used as sub-base for pathways and paving because it is excellent for drainage and it compacts well, providing a strong and stable base.

Rock is sorted in crushing plants according to size. Crushed rock is put on shaker screens, which vibrate. Rocks too large to fit through the holes in the first screen are further processed, while rocks small enough to fit through drop down to the next level of screens, and are either further processed or stockpiled according to size. This continues until all the rock is sorted properly.

Type 2 aggregate is essentially “2-inch minus,” meaning it passes through a screen with 2-inch holes, so its length or diameter must be less than two inches. Another common aggregate size is Type 1 gravel, essentially “1-inch minus.”

Aggregate for the project was sourced from a quarry in nearby Goffs.

Most of the road was built lower than the surrounding homes and is lined by trees to reduce noise and visibility for the community.

The location of the connector was chosen to avoid or minimize the impact to environmentally sensitive areas such as wetlands.

To keep construction costs down, companies establish a lot of small quarries widely dispersed throughout the province, especially in areas where construction projects are planned, so aggregate can be sourced relatively close to construction sites. This reduces the amount of fuel used in trucking the aggregate, which reduces cost and lowers emissions from fuel consumption.

Keeping costs down means more paving can be done and reduces the financial burden on taxpayers. This model is the only economic way to build and maintain our roads and highways, and to keep our infrastructure safe for Nova Scotians.

The network of small quarries means aggregate quarried in a community is generally used in the community to improve the local road system and make it safer for residents.

It also makes aggregate available to local contractors for other types of construction projects in the community. For example, a typical single-family home contains about 160 tonnes of gravel (about 11 truckloads) beneath the basement floor, as drainage rock around the foundation to prevent basement flooding, and in concrete walls, floors, steps, sidewalks, patios and driveways.

Aggregate is the most-mined material in the world because it is used in virtually all infrastructure, including homes, roads, schools and hospitals.