Milton, Ontario project affects abandoned industrial property

November 28, 2011

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Hazco Environmental Services Ltd. excavated and hauled away approximately 5,500 tonnes of hazardous soils and 28,000 tonnes of non-hazardous soils from the abandoned industrial site. One of the largest road projects ever undertaken by the Town of Milton has also been the catalyst for the remediation of a brownfield site which will eventually be turned into housing.

The $49-million Main Street underpass is designed to reduce vehicle idling times and safety concerns at the point where that street crosses the heavily used four-track CP rail line.

At the same time, its construction will create an S-curve realignment of the street which means it will have a major impact on a long-abandoned industrial property on the south side.

“The project requires a deep slice though the property to allow the street to pass underneath the rail line,” says Derek Stewart, associate partner, Ecoplans Ltd.

As a result, the rail separation is intertwined with the remediation of the three-hectare industrial site, says Stewart, whose firm is the environmental consultant for both the remediation and the underpass.

McCormick Rankin Corp. is the overall detailed designer and contract administrator.

The property was the location of a zinc-oxide manufacturing plant from the early 1950s to the early 1990s and was once occupied by several buildings including the main manufacturing plant, a baghouse, a furnace production and storage building, as well as underground storage tanks.

An investigation of the site by Ecoplans, which included drilling 31 boreholes and a comprehensive sampling and analysis, showed large areas of contaminates such as heavy metals.

“Most (of the contaminants) were in the top metre and a half of soil, although some went deeper.”

A number of remedial options including encapsulation were proposed. “But the town was concerned about liability and rejected that option.”

There was also certain urgency. As the west half of the municipally owned site will be the area most directly impacted, the town decided to sever the land. It has retained ownership of the west parcel, but has sold the east half to a developer who has proposed using it for a mixed-used commercial/residential development.

So, a more traditional remediation method was chosen. Over a two-month period, Hazco Environmental Services Ltd. excavated and hauled away approximately 5,500 tonnes of hazardous soils and 28,000 tonnes of non-hazardous soils. The Hamilton-based firm also trucked in and applied 15,000 tonnes of clean backfill and then lined the property limits with a PVC geothermal membrane to prevent migration of contaminants which had been detected on adjacent properties, says Stewart.

Despite the amount of truck traffic entering the site on a daily basis, every effort was made to minimize the project’s impact.

“The streets were kept clean by the contractor using a sweeper and water truck and dust levels were controlled by the application of water using a water truck.”

Traffic control was also managed by the contractor. Site egress and exit were strictly controlled through a traffic management plan agreement with the town.

The east half of the site — the parcel which will eventually house the condominium — is now being used as a staging area by BOT Construction, the grade separation contractor.

At this point, the rail grade separation is in a very preliminary stage. BOT has moved rails to accommodate a temporary detour and is now in the process of removing the contaminated soil beneath those tracks.

It will take four years to fully complete the underpass, says John Brophy, the town’s senior manager of infrastructure. “However, after two years we will be able to direct two lanes of traffic under the rail bridge.”

The catalyst for the project is the heavy amount of road and rail traffic at the crossing. Its daily “exposure index” is 300,000. The index is the term used by the Canadian Transportation Agency to gauge road and rail traffic.

“The trigger limit when a grade separation is warranted is 200,000, so this location is warranted to be grade-separated.”

Compounding the potential safety hazards of that high traffic are poor sightlines and the fact the tracks are at an extreme angle to the road, says Brophy.

Source: dcnonl.com