August 2008

Engineering Exchange

Engineering a greater environment

By H. Weldon

Protecting the marine environment with a silt curtain during civil works

In 2000, the Ministry of the Environment (MOE) conducted an extensive soil sampling exercise in the city of Port Colborne, Ontario. Findings showed nickel levels that exceeded MOE generic guidelines in a 29 square kilometre area fanning out from Vale Inco’s nearby refinery. Soon, the city was up in arms against the mining company. Vale Inco turned to Jacques Whitford to assist them in better understanding the extent of the alleged contamination and to find viable solutions as needed.

Jacques Whitford scientists, engineers and risk assessors, led by project manager Eric Veska, embarked on a comprehensive eight-year community-based risk assessment in the city and surrounding area. Challenges were met and overcome on a daily basis. Veska recalls facing accusations and anger at the frequent city meetings. The town hired (at Vale Inco’s expense) a third-party consultant to follow the Jacques Whitford team every step of the way to assure the public that a transparent process was being followed. “They were always there,” Veska exclaimed, “questioning and challenging our methods, and then performing the exact same tests we were doing.” Veska often found himself swamped with all the extra paperwork generated by the third-party consultants, slowing the entire process down.

Sampling from homes was time-consuming and often difficult. Several people were uncooperative and would not allow scientists access to their property.

Soil samples were taken at hundreds of homes, and dust and indoor and outdoor air samples were collected throughout the area for chemical analyses. Questionnaires were filled out by residents to plot everything from how much water they drank and where the water came from, to what they ate and how much time they spent indoors and outdoors. Water from private wells and the city’s supply was tested. Vegetables growing in gardens were tested. Local produce from grocery stores was tested. Crops, earthworms, frogs, insects, voles, poultry, eggs, trees and natural vegetation were all sampled and tested.

Meanwhile, long-term studies in laboratories and at universities examined phytotoxicity, earthworm dose-response toxicity and the ingested nickel uptake among rats in vivo. Jacques Whitford’s work in gathering site-specific input values on the toxicity of soil nickel to humans and the ecology was used to develop risk-based soil criteria for the community of Port Colborne.

In the end, it was found that the nickel present in the Port Colborne soil was predominantly insoluble nickel oxide. This was good news because nickel oxide, when ingested, enters the bloodstream only at very low concentrations and is quite safe at the levels found in environmental media around Port Colborne.

Phytotoxicity tests showed that only a two square kilometre area of farm land required remediation. Farmers were encouraged to distribute limestone and manganese in the affected soil to effectively reduce nickel uptake by crops.

Only in one small company-owned woodlot was nickel concentration found to be higher than levels considered safe for earthworms. No immediate remediation is planned for this woodlot, unless its zoning changes to agricultural.

In 2004, Xstrata Nickel hired Jacques Whitford’s Montreal office for assistance in completing the environmental and social impact assessment (ESIA) for the proposed wharf reconstruction in Deception Bay. In accordance with the environmental protection regime of the James Bay and Northern Quebec Agreement, its own views and those of Xstrata, the Jacques Whitford team worked closely with the local Inuit people to make sure the project would generate as little impact as possible. Meetings were held so that local villagers could express their concerns and ask questions. Taking into account what the local people wanted to protect was a big part of project planning. At the wharf site itself, some old asbestos contamination from a prior operation was discovered in the seabed, which Xstrata was quick to clean up. Dredged sediments were moved to land and the material was securely stored. Water collected from dredging was treated before being returned to the environment. Water quality, fish habitat, plant species and the local bird population were extensively surveyed in and around the project area. Certain areas near the wharf were demarcated and declared off limits for construction activity.

Fish protection in Deception Bay was one of the key factors considered. The adopted objective was to ensure no net loss of habitat, in accordance with the Fisheries Act. Also, any justifiable loss of fish habitat needed to be compensated for. An old collapsed culvert is scheduled to be repaired this year and upgraded to facilitate Arctic char passage and spawning, thus allowing better than 1:1 compensation for lost habitat. A section of the new wharf was designed to be crossed more easily and safely for Lake Duquet area villagers travelling by snowmobile.

During the construction of the wharf, a local whale watcher was hired to keep an eye on whale movement in the bay. All work was stopped when a whale approached to within one kilometre of the construction site. Because nothing could be done to encourage whales to leave the area, work could only continue when they left of their own volition. Blasting was limited on land because of reverberation, and no underwater blasting occurred. During wharf construction, a $500,000 silt curtain was installed in the water around the wharf site to contain and limit suspended solids in the bay.

This was the Montreal office’s first project with Xstrata. Project manager Raymond Goulet found the experience rewarding. “There were interesting challenges on this project and Xstrata did everything by the book and often exceeded environmental requirements as a means of being good custodians of the land,” Goulet stated. “There is a lot of competition in Quebec for engineering consulting. Most of them cover environmental engineering as a sideline. I believe that Xstrata chose us because environmental work is our main business and we do it best.”

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