Sunday, July 21, 2002 Back The Halifax Herald Limited

Acid level at manhole probed
Alum may have been dumped into storm-water system

By Chad Lucas

Investigators and response teams diverted water and pieced together clues Saturday at another possible entry point for the pollutant that wreaked havoc on the Little Sackville River.

A substance that contaminated the river on Thursday killed at least 4,000 fish, many of them salmon.

Tests taken Friday and Saturday turned up abnormally low pH levels - a sign of high acidity - at the second of three manholes behind Sobeys near Downsview Mall.

The manhole connects to a storm-water line that flows into a nearby lagoon where the highest levels of pollutants were found.

Municipal water crews diverted water from the storm line into a parallel sewer line that flows to the Mill Cove treatment plant in Bedford, Environment Department spokesman Robert Moffat said.

The cause of the acidity at the manhole, as in the rest of river, remains a mystery, he said.

"That's the million-dollar question right now."

Investigators with the regional environmental emergency team believe the damage was caused by either a natural runoff of pyritic slate or a human-caused influx of aluminum hydroxide.

"We're pursuing both possibilities right now," Mr. Moffat said.

Investigators planned to send a video camera through the storm sewer line Saturday night to check for cracks or leaks where contaminants could have seeped in, Mr. Moffat said.

Tests last week turned up a high concentration of aluminum hydroxide in the lagoon near Wal-Mart, which feeds into the river.

Peter Hennigar of Environment Canada said Thursday that the aluminum hydroxide probably came from alum, a common commercial product often used in water treatment.

The concentration of the compound is so high that it must have been dumped there, either accidentally or intentionally, Mr. Hennigar said.

Crews were still draining the lagoon Saturday after a heavy morning rainfall forced some water from the contaminated pond back into the river.

But pH tests showed the rain didn't cause any further damage to the river, Mr. Moffat said.

"It did force some leakage . . . but it didn't take with it any contaminants we could find," he said.

Crews were working Saturday to extend and fortify a dam to cut off the lagoon from the river.

Walter Regan, president of the Sackville Rivers Association, said he was glad to see people working so hard to return the river to normal.

"I'm extremely happy with all the activity I see," he said.

There was some good news Saturday: the river had recovered enough to allow barriers, keeping fish out at the mouth of the river, to be taken down.

"At this point, we feel confident that the adult fish would be all right if they decide to return," Mr. Regan said.

clucas@herald.ns.ca


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