Soil near Kalemi Dene School in N'dilo is safe, according to soil assessment

New soil samples taken close to the Kalemi Dene School in N'dilo show arsenic levels in the area are well below the acceptable limit, which means no need for remediation or further sampling, according to a recent study by the the federal government and the Yellowknives Dene First Nation.

The soil assessment was donein Augustto address community concerns about arsenic contamination near the school and the daycare.

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Now that N'dilo residents are aware of the latest findings, "most people feel that they're safe," said Edward Sangris, chief of the Yellowknives Dene First Nation in Dettah on Monday.

"Most people feel that it's OKnot to do further investigation."

The assessment, conducted by Yellowknives Dene First Nation-owned Det'on Cho Corporation and Whitehorse environmental consulting firm Hemmera, found arsenic concentrations near the school rangefrom 19 to 64 milligrams per kilogram (mg/kg) of soil.

The Northwest Territories government considers soil in residential areas safe if arsenic levels are below 160 mg/kg.

Previous testing showed high levels

Arsenic occurs naturally in Yellowknife-area soil at concentrations of about 150 mg/kg, according to Crown-Indigenous Relations and Northern Affairs Canada, the federal department that carried out the assessment.

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However, the chemical elementis present at higher levels in some areas as a result of past activities at Giant Mine.

Over the years, soil sampling in N'dilo has repeatedly shown high concentrations of arsenic.

But none so alarming as tests done in 2012, which found arsenic concentrations in the soils near the school higher than 1,000 milligrams per kilogram (mg/kg).

A 2014 assessment carried out by Det'on Cho Corporation and Stantec found concentrations near the school ranged from 20 mg/kg to 200 mg/kg.

In 2017, a report from the Northwest Territories Geological Survey found arsenic levels in N'dilo soil ranging from 130 mg/kg to 280 mg/kg.

Crown-Indigenous Relations and Northern Affairs Canadacommissioned Environmental Sciences Group, a research organization at the Royal Military College in Kingston, Ont., to review all previous reports on N'dilo soil since 2000.

The group determined that the elevated arsenic found near the school in 2012 was "an outlier," and "not representative of the amount of arsenic in the soil in and around N'dilo," said Matt Spence, the department's regional director general Northwest Territories.

"It looks as if arsenic levels in N'dilo are below residential threshold so that the residents of N'dilo are in fact safe," he said.

Nugget Effect

The federal departmentdoes not know why exactly the 2012 test registered such high arsenic levels, but speculatedit's possible arsenic is attracted to a certain kind of soil, andthe chemical became concentrated in one small area.

Officials callthis theory the "nugget effect."

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Spence said N'dilo has been surveyed extensively andit's "unlikely we're going to find any other nuggets."

For N'dilo residents still be worried about arsenic levels in their gardens or in children's play areas,Spence says the department will do real-time soil screening for anyone who asks.