MMSD generator needs repair

Milwaukee Metropolitan Sewerage District Manager of Contract Compliance John Jankowski examines a Jones Island generator’s faulty rotor. The two generators are approaching the end of their life spans and would cost between $12 million and $15 million to replace.

Photo by Sean Ryan

The Milwaukee Metropolitan
Sewerage District Tuesday began a speedy project to repair one of the two generators
that power the Jones Island Wastewater Treatment Plant.

The plant has two
on-site natural gas turbines, each with the same basic plumbing as a jet engine,
that keep it operational even if the area’s power goes out. The district
purchased them 35 years ago, and they cost between $12 million and $15 million
apiece in today’s market. The roughly 25-yard-long generators are too noisy
to talk next to, and their 900-degree Fahrenheit burning temperatures roast the
high-ceilinged warehouse they sit in side-by-side.

On June 27, the operator
of generator No. 2 noticed that its rotor was vibrating too much, said John Jankowski,
MMSD manager of contract compliance. So the district called in ReGENco, a West
Allis turbine and generator equipment repair shop, to check it out. The MMSD Commission
approved the repair project Monday.

On Tuesday morning, ReGENco’s
crews were removing the faulty generator’s rotor so they could move it to
the shop for a complete diagnosis. Jankowski said the MMSD was expecting an assessment
in three or four days, and then ReGENco could give them a better estimate on the
cost and schedule of repair.

“We’re taking that rotor and removing
it from the generator, and taking it to the shop to confirm our suspicions,”
Jankowski said.

Lengthy repairs

Either of the two 16-megawatt generators
can power the plant’s wastewater treatment operations unaccompanied, so unit
No. 1 will power the plant during the estimated three-week repair time for its
fellow. However, the plant would need more energy if it wants to turn on the pump
that would carry water to the plant from the Deep Tunnel, Jankowski said.

In
that event, the plant would switch on one of the two power lines that can feed
it electricity from the Wisconsin Electric Power Co. Jankowski said that purchasing
the power could get expensive if done during the day.

The power company
charges the MMSD a demand charge, on top of the normal rate, any time Jones Island
uses its energy during the daytime and early evening hours. The charges are meant
to keep demand down when most people use electricity.

“The power company
wants to level the demand, and one way to do it is to create a disincentive to
use it,” he said.

Monthly charges high

Jankowski said the charges
can add up to $100,000 a month. In order to avoid the demand charge, Jones Island
usually won’t tap into the power company’s supply until after 10 p.m.
when it doesn’t apply. Jankowski said that, barring an unusually heavy rain
over the next month, Jones Island could avoid using the Deep Tunnel pump during
peak hours.

He said operators turned on the Wisconsin Electric lines Monday
night so they could empty the Deep Tunnel and wouldn’t have to use the pump
during peak hours on Tuesday to keep up with the morning rains. The tunnel, which
can hold 405 million gallons of sewage, only held 3.5 million gallons at 10:15
a.m.

The two generators and dual power lines are meant to ensure Jones Island
never experiences a blackout. Jankowski said that the MMSD Commission, when it
approved the repair job Monday, said he should try to find a backup system to
replace generator No. 2 during the repair work. He said it would be tough order
to fill, but that his continuing search had turned up one company that provided
an estimate.

The malfunction also raises the issue of replacing the two
aging generators, Jankowski said. The district will include a replacement strategy
for the generators in its 2020 Facilities Plan, which will identify advantageous
policies and major projects to pursue over the next 15 years.

“We
overhauled them 10 years ago,” Jankowski said. “Generally, our expectation
was to keep them in service until our 2020 Facilities Plan.”

Sean Ryan
can be reached at 414-276-0273, Ext. 107, or by email.