Last summer I commented on a provincially approved contaminated soil dump five kilometres uphill from the principal drinking water supply for thousands of residents of Shawnigan Lake.

Sited in an old quarry 50 kilometres north of Victoria, the dump is to receive up to five million tonnes of contaminated soil over 50 years.

Two surface streams drain from the site into Shawnigan Lake.

Friday, following a heavy downpour — more than 30 millimetres fell — containment on the waste treatment site was apparently breached.

The Vancouver Island Health Authority then warned householders at the south end of Shawnigan Lake not to drink the water.

Dr. Murray Fyfe, speaking for VIHA, told our legislature reporter, Rob Shaw, the water ban was precautionary. Public health officials don’t yet know if potentially hazardous chemicals from the waste treatment plant went into the lake. He did confirm “there are a number of potential contaminants in the soil.”

You can say that again.

Andrew Weaver, the scientist who doubles as provincial Green party leader, sampled run-off from the site last summer. He provided evidence then of heavy metals concentrations 19-times greater than samples collected downstream.

This provided “clear evidence that run-off from this site failed drinking water standards at the point of entry with Shawnigan Creek,” he said, and suggested a source within the landfill. Weaver called for deep drill core testing of already dumped materials.

Weaver found thorium, lead, niobium, zirconium, vanadium and 13 other metals including chromium, iron, tin and cobalt below the site. Some of these bioaccumulate, so minuscule amounts today can mean huge problems tomorrow.

In any event, residents were told by VIHA Friday not to use water for washing clothes, dishes or for personal hygiene. In other words, don’t even touch it.

Environment Minister Mary Polak brushed off residents’ concerns Monday. She told Shaw preliminary testing shows no contaminants “of any concern for human health” and that her staff visited but saw no water coming off the site where contaminated soils are.

That’s odd. Cowichan Valley Regional District director Sonia Furstenau, who represents Shawnigan, has a video. It clearly shows muddy water boiling right out of the site and into one of the streams feeding the lake.

Note that Weaver’s sampling occurred during a drought. Now we’re into the winter rains. And the province’s own climate change projections are for more frequent extreme rainfall events during the proposed half-century for the waste treatment facility.

Obviously, if waste water can’t be prevented from leaving the site now, it raises serious questions for both residents and for government policy in the future.

The central point, the one that Polak doesn’t seem to grasp but that Weaver does, is that “water was not supposed to leave the site.”

“That’s very, very serious,” Weaver said. “Extraordinarily serious.”

Yet even as the VIHA water ban remained in place, trucks continued to dump contaminated soils at the landfill, he said.

“There is a dereliction of duty here,” he said. “We need to have an independent investigation.”

Furstenau wants Polak to revoke the operating permit for the contaminated waste site.