I-35W Bridge Collapse - Week 22

Week 22 by Ivy Chang | September 28, 2010

Work stopped for a few hours on the I-35W bridge construction on January 9 at about 9 a.m., when an oil tanker truck overturned and spilled 7,000 gallons of unleaded fuel onto the freeway near downtown Minneapolis.

The fuel gushed at a rate of about 100 gallons per minute, leading to a hazardous situation. Nearly all of the oil seeped into storm drains, some of which lead into the Mississippi River. Emergency crews sprayed foam and dropped sand on the ground to contain 700 to 800 gallons of fuel at the accident site, then vacuumed the fuel into tanks, according to the Minnesota Pollution Control Agency.

Crews collected fuel from storm sewer

A cleanup firm placed a semicircular containment boom on the river near the I-35W bridge site to collect the gasoline as it came out of the storm sewer near the bridge. MPCA said much of the oil will be vacuumed off the river surface.

The Minnesota Department of Transportation closed two freeways and other roads, and rerouted traffic through the afternoon.

The Commissioner speaks out

A Star Tribune article said that Department of Transportation Commissioner Carol Molnau had a meeting with Gov. Tim Pawlenty in November when they discussed the possibility of her resigning. Molnau said the governor left the decision to her and she stayed because she does not feel she has done anything wrong.

She also defended her actions on the bridge collapse, saying she allowed engineers to make decisions about bridge repairs, she still has the governor’s support amid critics in the Legislature, she kept a low profile in the days following the collapse because her appearances became very political, and she will not speculate on any findings by any agency.
Defending department actions

Molnau said her assistant is not the decision maker as many people speculated but is always included in weekly meetings on important matters as part of a leadership process.

In the case of her emergency management director, Molnau said perhaps better supervision was required at MnDOT, but she did not see this case as symbolic of her department’s internal problems.

As for her absence from the legislative commission meeting where the auditor outlined his findings of Sonia Pitt, Molnau said she had to go somewhere but she can’t recall.

Louder drilling at construction site

Crews began drilling 69 foundation shafts for the Second Street Bridge on the north side of the I-35W bridge site. This accommodates Abutment 5 on higher elevation, and crews will use three large air compressors to power the drills.

At Piers 2, 3 and 4, 36 out of 40 shafts have been drilled and 35 of them have been filled.
Excavation for the footing at Pier 3 is complete; crews built forms and filled them with concrete. Next week, crews will start excavating for footings at Piers 2 and 4, which involves removing a couple thousand cubic yards of material at Pier 2 and then setting up the forms to be filled. At Pier 4 no excavation is needed.

Supplies for superstructure delivered

Truckloads of supplies for the construction of temporary scaffolding were delivered. The falsework, as the scaffolding is called, will support the forms for the bridge’s superstructure. Construction will begin later this month on the falsework and continue until April.

North of Washington Avenue on the unused stretch of I-35W, carpenters are building the casting beds and forms used to cast the segments of the main bridge span.

Work around the clock led to using balloon light that can illuminate about an acre without as much glare as the construction lights normally used.

Updates on the bridge

MnDOT’s project manager, Jon Chiglo, is conducting regular interviews with Twin Cities’ radio and TV several mornings each month until the bridge is complete. Chiglo will give a progress report on the construction at each interview.

The Sidewalk Superintendent talks continue each Saturday at 11 a.m. to provide an overview of the project. In addition, signs along the Tenth Avenue Bridge provide a self-guided tour for people who wish to go to the site when they can.

Representatives from MnDOT and Flatiron-Manson will provide updates to business and neighborhood associations and other groups if they want a presentation.

The public is encouraged to call the hotline, (612) 236-6901, between 7 a.m. and 8 p.m. to ask questions about the project or to arrange a presentation.