Richard Gleeson
Northern News Services

Yellowknife (Apr 19/02) - Guidelines that will likely govern the surface clean-up of Yellowknife's two gold mines will be unveiled next week, just before the release of the conclusion of a five-year of research program with an almost identical aim.

A committee representing industry, public health and government will reveal what it believes are safe standards for arsenic content in Yellowknife soils at a public meeting Tuesday starting at 7 p.m. at Northern United Place.

The Yellowknife Soil Arsenic Remediation Committee will release standards for residential, recreational and industrial land uses.

News of the presentation came as a surprise to Ken Reimer, a Royal Military College of Canada instructor in Kingston, Ont., overseeing a research program on arsenic in Yellowknife soils.

Reimer said the RMC research will gauge more precisely than the work YSARC will present what safe arsenic levels would be.

"It's not like it's six months or a year from now, we've got the data now," Reimer said. "We had hoped we would meet with them and show them this information and that they would factor that into their process."

Reimer said the main difference between the two bodies of work is that YSARC's research is based on the assumption that 100 per cent of the arsenic ingested would be absorbed into the bloodstream.

The RMC studies have focused on measuring how much of arsenic ingested is absorbed into the bloodstream of humans and how much is absorbed by plants.

RMC is also differentiating between toxic and non toxic forms of arsenic. Compounds such as arsenic trioxide are highly toxic. Others, such as the arsenic contained in shellfish -- is not toxic.

"We recently advised YSARC that these results clearly demonstrate that the arsenic risk is much less than that predicted by the standard approach they requested from RiskLogic," Reimer noted in an e-mail.

RiskLogic is the consultant YSARC hired to do three reports. The standard approach assumes 100 per cent of arsenic ingested will be absorbed into the bloodstream.

If adopted by the Mackenzie Valley Land and Water Board, the YSARC guidelines will apply to the clean-ups of Giant and Con Mines.

Soils in the city were contaminated by arsenic dispersed in the air during the refining processes that took place at the two gold mines that flank the city.

Most of the contamination occurred long ago, before the introduction of pollution-control technology.

Two of the RiskLogic reports that will be presented focus on the human heal and ecological risks posed by arsenic contamination in Yellowknife. A third will specify what background levels of arsenic are in the area and recommend human-health-based remediation standards.

Canadian soils typically have arsenic levels of 4-14 ppm. A Royal Military College report released last year suggested arsenic occurs naturally in the Yellowknife area in concentrations of 3-150 ppm.

The standards will have huge implications on the cost of the clean-ups.

In a reclamation plan it developed for Con mine, Miramar proposed a standard of 370 parts per million of arsenic in soils on its lease.

If that standard is accepted, Miramar calculates it will have to excavate and remove 98,000 cubic metres of soil from the site.

The conclusions of the RMC research, including the arsenic levels it indicates are safe, will be presented here in late May or early June, Reimer said.