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 |