Crew to begin inspection in sewage tunnels
Team searching for flaws that contribute to pollution
By MARIE ROHDE
Milwaukeee Journal Sentinel
A 5,000-pound truck will be lowered nearly 300 feet beneath
the surface today for the belated first inspection of
Milwaukee's sewage storage tunnels, according to sewerage
Tom Wagner, manager of a team of private firms doing
the inspection, said a five-man crew riding on the truck
will videotape the entire length of the 17-mile deep-tunnel
system, looking for obstructions, leaks and flaws that
could contribute to the ongoing problem of dumping raw
sewage and pollution of the groundwater.
Rust/Harza, an engineering firm, is heading the team
that includes Super Excavators Inc., Quality Videos and
Platt Construction Inc. on the $1.2 million project.
The crew plans to inspect two or three miles of tunnel
a day and must be done before Feb. 28, when the rainy
season begins. Heavy rains, which are not expected this
week, could cause problems, but snow melt expected today
will not likely be a problem, Wagner said.
The truck will be lowered into the tunnel today at S.
6th St. and W. Cleveland Ave. and brought back up each
night at different locations.
Although it was supposed to virtually eliminate the need
to dump untreated waste into local waterways, about 13
billion gallons has poured into Lake Michigan and its
tributaries since the deep-tunnel system opened in late
Initially, the tunnels were supposed to be inspected
after they filled for the first time and then once every
five years. The Milwaukee Metropolitan Sewerage District
resisted making a full inspection, but, under pressure
from environmentalists and regulators, officials agreed
last summer to have the job done.
"Our prime concern is the condition of the air (in
the tunnels)," said Wagner, who has worked on the
inspection of other smaller sewers in Milwaukee.
Each man will wear protective clothing - but not a biosuit
- and will have compressed air available, Wagner said.
Equipment will monitor their crew's oxygen levels, and
monitors on the truck will constantly check for methane,
a gas that can explode, and for hydrogen sulfide, a gas
that smells like rotten eggs and can kill if the concentrations
are high enough.
If either of the gases is detected, the truck will back
up immediately, Wagner said. The vehicle moves at 8 mph.
Three workers were killed in 1988 when methane exploded
during the construction of the tunnel system.
Wagner said huge fans began venting the tunnel system
24 hours before the crew was scheduled to enter. Tunnel
air is being vented at Jones Island and should not create
an odor problem in the area, he said.
The eight-wheel-drive truck is more than 12 feet tall
and can maneuver through 16 inches of water. Wagner said
preliminary examinations had found as much as 6 inches
of sludge at the lowest point in the tunnels but that
is not expected to be a problem.
The crew is not equipped to fix cracks or flaws it finds,
Wagner said. The entire length will be videotaped, and
precise locations will be noted for later work. The vehicle
does have a winch and can move some obstructions.
The system has three main segments - one running north-south
along the Milwaukee River to Jones Island, one running
east-west from near Miller Park to Jones Island, and the
third along the Kinnickinnic River.
Bill Graffin, a spokesman for the sewerage district,
said it had not been determined whether the inspection
tapes would be released immediately or in April, after
an analysis has been completed.