Dubuque bluffs renovated and ready for spring rain - KWWL - Eastern Iowa Breaking News, Weather, Closings

Dubuque bluffs renovated and ready for spring rain

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DUBUQUE (KWWL) -- Last spring, all that moisture caused a retaining wall to collapse on Dubuque's bluffs. During repairs, the city discovered much of the bluff was unstable. That prompted a major construction effort.

Deep within the limestone blocks of Dubuque's famous bluffs. Lays years of erosion from wet spring weather.

"They look like large blocks but actually what they are is the front block that you see up here was like a decorative facious stone," said Civil Engineer Jon Dienst.

Behind that front: three to four feet of limestone rubble. Hauled in to build part of the bluffs more than 100 years ago. Which explains why, in April 2008, one of the wettest springs Dubuque has ever seen, several walls collapsed.

"We got on it quickly. No one was hurt. There was some structural damage," said Dienst.

Now, a new wall sits above the Theresa Shelter -- built using new technology to make for both a safer and more cost effective wall.

"Your construction from the bottom up. You're putting a lapse of limestone in the front, behind that a 2 foot layer of concrete," said Dienst.

A high density foam called geo-foam replaces the limestone rubble, making a stronger base for the wall.

"You can drive trucks across the styrofoam, walk on it and there's very little deflection at all on this material," said Dienst.

And a lot less pressure on the stone wall. Making it safer for people below. Dienst says the city is currently rebuilding two other walls. And plans to build three more this spring. And with the years and weather these bluffs have seen, he says the renovations are long overdue.

"I'm sure it lasted beyond what the original designers had intended, it out lasted their lifetime," said Dienst.

City engineers say if you notice a city wall deteriorating. Call the City of Dubuque Engineering Department immediately.

Online reporter: Lauren Squires

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