Canadian Consulting Engineer

Site Remediation: Ugly Duckling

As cities across Canada turn blighted industrial lands into thriving urban districts, engineers and developers face the challenges associated with brownfield revitalization: environmental liability, c...

June 1, 2002  By Virginia Heffernan

As cities across Canada turn blighted industrial lands into thriving urban districts, engineers and developers face the challenges associated with brownfield revitalization: environmental liability, community backlash and the high cost of remediation.

Brownfields, by definition, are “abandoned, idle or underused industrial sites where expansion or redevelopment is complicated by real or perceived environmental contamination that can make redevelopment financially or logistically prohibitive.” Cities like Toronto, Montreal and Vancouver have such sites scattered along their post-industrial waterfronts.

Some brownfields have been sitting vacant for decades because their owners preferred to let the land go fallow rather than risk liability for future environmental problems. Developers shied away from remediation costs that the U.S. Environmental Protection Agency estimated to average $25 million per site. But today the situation is shifting. Innovative insurance products that can protect against future liability and cost overruns, cost-effective developments in remediation technology, and changing provincial legislation have made some of these ugly ducklings more attractive.

Stelco’s Swansea site

Advertisement

One brownfield site that has overcome the odds stacked against its renewal is the former Stelco manufacturing plant site at the south end of Swansea village where the Queensway meets the Kingsway in Toronto’s west end. Identified by the city as long overdue for redevelopment, the site is now being remediated by consulting engineers Gartner Lee in preparation for the construction of a residential complex by Reon Development.

Also contributing their expertise to the project are Golder Associates, who are providing the geotechnical assessment needed to design the building foundations, and Marshall Macklin Monaghan, which is taking care of water supply and storm and sanitary drainage both on-and-off site. Read Jones Christofferson and BA Consulting Group are providing structural engineering services and traffic analysis, respectively.

In terms of location, the 13-acre site is a developer’s dream: close to the waterfront, High Park and the downtown, with access to public transportation and other infrastructure. Recognizing this potential, several possible buyers approached Stelco after it closed the site more than a decade ago. All but one were scared away by potential environmental liability.

Like most property along Toronto’s waterfront, the Stelco site consists of sandy backfill that was placed there in the early 1900s to enable building to take place along the swampy harbour. Environmental regulations were non-existent at the time, so the area was filled with whatever was available: rubble, bricks, metal scrap and the like.

Several years of nut-and-bolt manufacturing and leakage from oil storage tanks underneath the plant added to the landfill contamination. By today’s standards, the soils are unacceptable for residential use. The culprits include elevated levels of lead, zinc and copper, plus minor cadmium and mercury and discrete lenses of petroleum hydrocarbons. Fortunately, the metals and hydrocarbons are confined to the soils and have not affected the groundwater. Nor have they migrated off-site.

Reon hired Gartner Lee to complete an initial environmental assessment for due diligence purposes, then drew up a purchase agreement that included insurance to protect Stelco against future liability. In an unusual concession to the previous owner, Reon also guaranteed the site would be completely remediated, not just to a level determined by an environmental risk assessment. Stelco didn’t want any environmental problems associated with the site coming back to haunt it if the developer who bought the property disappeared in five, 10 or 50 years.

“The business deal was unique,” says Robert Leech, M.Eng., chairman of Gartner Lee. “It was important to Stelco that it be indemnified against future liabilities.”

After the two parties completed the deal, Reon faced further challenges. The city treated the project like a greenfield development, demanding that Reon make the same community contributions despite the high cost of remediation. The community was skeptical.

So Reon arranged a series of meetings that allowed residents of Swansea and city staff to voice their concerns. One of the neighbourhood’s biggest worries was that the view of Lake Ontario would be blocked by proposed high-rises on the site. Reon agreed to change the width and orientation of the buildings to maintain the view. The developer also made a number of other concessions including providing public green space and day-care facilities. Off-site contributions included upgrades to the Gardiner underpasses to the lake, a canoe storage building on the Humber River, and playground equipment.

In recognition of its public consultation efforts, Reon won a “Brownie” award from the Canadian Urban Institute for excellence in brownfields development. The consultation also helped speed the project through rezoning from industrial to residential use without a review by the Ontario Municipal Board. It took about a year for the rezoning to be approved.

“This is very fast for a site of this magnitude,” says Leech. “It shows that if you do things right and consult with the community, it shortens the approval process rather than lengthening it.”

The development, scheduled for completion by early 2005, will consist of three towers and 130 townhouses fronting on the Queensway. It will house more than 2,000 people in a total of 800 units and generate about $3 million in property taxes each year.

Soil clean-up

Anxious to have construction completed while the Toronto real estate market is still hot, Reon is paying a premium [undisclosed] to have the soil cleaned up by Gartner Lee as quickly as possible.

First, Gartner tackled the east side of the property, where contamination was primarily limited to metals. To distinguish metal-contaminated soil from uncontaminated soil, the company drilled shallow holes at 15-metre spacings, then tested the samples at an on-site laboratory. Pockets of contaminated soil were excavated and sent to a landfill licensed to receive it. Subsequent testing confirmed that the contaminated materials had been fully removed.

The western, larger half of the property where the plant was located is being remediated in stages. Gartner Lee will first separate and excavate any metal-contaminated soil. Bioremediation, a relatively new technique in Ontario, will be one of the options used to clean up any remaining soil contaminated by hydrocarbons, provided Ontario’s Ministry of the Environment issues a certificate of approval for its use on the site.

Bioremediation uses microorganisms to treat contaminants in soil and groundwater. The technique works by stimulating natural microbial activity to convert contaminants, usually hydrocarbons, into inorganic products such as carbon dioxide (CO2 ) and water. It is an attractive alternative to other remediation techniques such as incineration because it is usually less expensive and more acceptable to the public.

The process can take place either in-situ or ex-situ depending on the medium and the type and concentration of contamination. Many of the techniques developed in the United States, including bioventing, bioslurping and landfarming, have been adapted for Canada’s harsher climate where microbial activity is relatively sluggish. For example, Grace Bioremediation Technologies, sponsored by the Canadian government, patented a technology using proprietary “amendments” that stimulate microbes to break down some of the most toxic organic chemicals including polycyclic aromatic hydrocarbons (PAHs) and pentachlorophenols (PCPs). Grace has used the technology to treat several Canadian sites, including the Domtar wood treating plant in Trenton, Ontario.

In the Swansea case, bioremediation will take place above ground (ex-situ) using what’s called a biopile. The biopile consists of layers of contaminated soil wrapped in an impermeable plastic membrane to minimize the risk of contaminant
s leaching into the surrounding soil. Perforated pipes run through the pile to deliver moisture, oxygen and other nutrients to the bacteria. Fans and motors help maximize the bacterial degradation of contaminants by controlling the delivery system. Off-gases from the degradation are treated using carbon filters. Biopiles cost less than $150 per ton compared to $70-$550 per ton for landfilling, depending on the type of contaminant (source: Environment Canada).

Because most of the hydrocarbons at the Stelco site consist of BTEX compounds with relatively simple molecular structures, the contaminants are expected to degrade quickly — within weeks to months — compared to more complex hydrocarbons that can take months to years to break down. The biopile will be active during late spring and summer, when local temperatures are mostly likely to be ideal (18-25C) for biodegradation.

Still, because the soils on the site are heterogeneous and the company is just finding out what lies beneath the concrete slab that was once Stelco’s factory floor, Leech expects a few surprises as the project progresses. “From a remediation point of view, the site isn’t challenging, but from a logistical point of view it is,” he says. “We have to modify our plan of attack on a daily basis depending on what we find,” he says.

The heterogeneous soils also affect the foundation design. In order to get a better understanding of the subsurface, Golder Associates drilled several rotary holes to depths of 7-29 metres. The consultants found variable fill materials extending to depths of 10 metres and greater, underlain by native soils and glacial till and, at depths of 9-25 metres, by bedrock.

“The geotechnical design will have to take into account the numerous phases of construction of previous buildings of the Swansea Works facility dating back to late 19th century,” says Golder’s Anne Poschmann, P. Eng.

The 2,000 residents of the new development are expected to increase the population of Swansea village by 13%, placing a strain on the existing water supply and sewage facilities. Marshall Macklin Monoghan (MMM) has been hired to examine and provide solutions to water supply and storm and sanitary drainage both on-and-off-site.

According to MMM (which has also been selected to assist in remediation, transportation and public work planning for the $12.5 billion Toronto Waterfront Revitalization Task Force), the city will need a new 300 mm-diameter watermain along Windermere Avenue to support demand from the Reon development. The watermain will string its way through a multitude of existing services and utilities, both above and below ground. Where Windermere Avenue passes under the Gardiner Expressway the watermain will be constructed in an open-cut trench, introducing both horizontal and vertical working restrictions.

Legislation changes

Ontario’s Brownfields Statute Law Amendment Act, 2001 (Bill 56) grants some liability protection to companies that wish to develop contaminated lands and empowers municipalities to provide owners with tax relief for remediation in certain circumstances.

But Bill 56 still leaves property owners unprotected when it comes to city liability. It also doesn’t address regulatory or civil liability for off-site contamination and is short on financial incentives, says Osler, Hoskin and Harcourt.

Far more effective in encouraging brownfield development have been financial instruments introduced by the insurance industry to protect both owners and consultants. Examples include cost-cap insurance, which covers remediation cost overruns, and post-remediation policies that cover changes in regulations after the clean-up. There is also property transfer liability insurance to protect owners from environmental problems left by previous owners.

Soil remediation technology has also improved while its costs have dropped. One of the most promising techniques developed by Vancouver-based Bennett Environmental uses thermal desorption to breakdown chlorinated hydrocarbons such as PCBs and dioxins. A similar technique patented by Ontario’s EcoLogic has been demonstrated on a commercial scale at the General Motors plant in St Catharines. Though metal contamination is a bigger challenge because metals do not degrade, techniques like phytoremediation, which uses plants for metal uptake, are improving. The market for these types of solutions is growing as more and more substances are banned from landfills in the United States, and increasingly, in Canada.

Canada lags far behind the United States in brownfield development. More research and changes to legislation are needed before techniques like bioremediation can replace the outdated, passive solutions such as landfilling as a means of transforming old industrial lands back to something resembling their original pristine state.

Virginia Heffernan is a Toronto-based freelance writer.

Categories

Engineering


Print this page

Related Stories

Leave a Reply

Your email address will not be published. Required fields are marked *

*