The city of Davenport will use its $1.5 million contingency fund to help keep the $36 million Westside Diversion Tunnel project moving along.

Thanks to what workers are calling an underground “lake” of water that no one knew existed, engineers are having to get creative to finish about 1,000 feet or so of the tunnel.

Discovered in early March, the water was believed to be a manageable obstacle.

When work crews turned off their pumps, however, the water rose right back into a giant cavity under the city.

“We began to sense this was not a water pocket,” said Mike Clarke, head of Public Works. “We brought close to 1,000 years of engineering expertise into one room and began thinking our way out of this thing.”

With the size of the collection of water estimated at 2,000 feet by 2,000 feet, one thing is clear, Clarke said: “We’re not going to drain the bathtub. It’s too big.”

The solution, instead, is a collection of “de-watering wells.” The plan is to use wells and pumps to control the water in specific areas where the tunnel is being dug. When the tunnel drill reaches certain areas, the wells will be used to keep the water out of its way.

“How many wells?” Clarke asked. “We don’t know.”

He also does not know what the final extra cost will be.

“I’m hearing it’s going to be somewhere around $4 million,” Mayor Bill Gluba said. “I do know that we paid $1.7 million for a design, which included borings to show what’s underground, and we expected it to show if there’s a lake down there.

“I’m looking into the possibility, with the council’s approval, of having someone review the work of the engineer we paid.”

Clarke said the cost likely will be somewhere north of $2 million, “but hopefully not over $4 million.”

“We’ve got one location where we’re going to try out our engineering and see how that works,” he said. “We may have to alter our hydraulic model a little bit. But once we know what that will cost, then we’ll be able to extrapolate the cost out to the rest of the distance.”

Clarke said he will meet with the City Council in a month when he has a more solid handle on the cost.

Aldermen unanimously approved of Clarke’s use of the contingency funds at Wednesday’s Committee of the Whole meeting so that the project can continue to move forward.

He added that a contingency fund of 10 percent to 15 percent is written into every construction project because unforeseen issues usually arise.

The total cost of the three phases of the Westside Diversion Tunnel, currently in Phase II, is estimated to be about $36 million because some bids have come in lower than expected. “That’s a good ballpark figure,” Clarke said.

Phase I was awarded at $12 million and changes still are being cleared out in that contract. Phase II was awarded at $15 million. Phase III has not gone to bid.

Clarke added that so far the project is ahead of schedule and is on budget.

The city paid Stanley Consultants, whose Quad-City office is in Muscatine, for the tunnel’s design.

Vice President and Senior Project Manager Pat Mullin said more soil borings were performed on the project than is typical. The studies showed pockets of sand and gravel, which contained water, and the design included a process for dewatering them.

The discovery of a much larger pool was “an unforeseen condition,” he said, adding, “Any time work is performed in underground conditions, there is an element of uncertainty. The quantities of water now found were unexpected and could not have been determined by standard engineering investigations.”

Mullin also said the boring samples were not taken by Stanley, because the company hired another firm for some of the tunnel work. The company, which he did not name, specializes in geotechnical work, and another firm that specializes in tunnel design also was on the job, he said.

“Stanley Consultants will continue to work with the city to resolve the matter,” he said.

Although the mayor acknowledges having no engineering background, he said he wants proof that enough studies were done before the digging started. He said the costly probe of the path should have revealed the water.

“They didn’t find, essentially, a lake down there,” he said. “How come they didn’t find the water, and we did?”

Clarke said he thinks the engineer used a reasonable number of borings at appropriate locations along the tunnel’s route. It is not unusual, he said, for boring samples to miss what cannot be seen below the earth’s surface.

Fortunately, the delay in finding a solution for dealing with the water was well-timed, he said. The equipment being used to dig the tunnel happened to be scheduled for routine maintenance and has been out of commission for several weeks.

He said he is confident the new strategy will work, adding that he cannot be certain, because the solution is a hydraulic model that has not been tested.

Meanwhile, Alderman Ray Ambrose, chairman of the council’s Public Works Committee, said he wishes the city had committed money to the tunnel two decades ago when the cost was about one-third what it is today.

He said too many government regulations, along with normal cost-of-doing business increases, are taking the price tag ever higher. He said he is not convinced the plan for dealing with all the underground water will be successful, but he hopes the estimated costs are accurate.

“We’re looking at the top end (of cost) and praying for the bottom end,” he said. “We’re not going to know anything until we dig some wells.

“The poor taxpayers are holding the bag.”

(Thomas Geyer contributed to this report.)

(11) comments

Downtrodden

Big projects inevitably will have big problems occur. No risk, no reward. The contractor, Stanley Consultants, should be held liable to some extent. Whoever they contracted obviously missed "a lake", so a corner or two must have been cut. I know the Huns will cry about any form of government doing anything for the public good, but 25 years ago, the East Side Diversion Tunnel was built. Now the entire NE part of Davenport is sprawling with businesses and residences, we have Elmore Ave. and the millions of dollars in tax revenue it gives the city,i.e. lowering the individual tax burden. It was a cash cow for Davenport. West Side Tunnel will do the same. Patience naysayers, this will most certainly pay off in the long run.

TONYPHERE

Davenport comes up with many ideas to waste money. its okay just leave the taxpayers to hold the bag. BUT DONT ASK THE TAXPAYERS WHAT THEY WANT.

Over taxed

“The poor taxpayers are holding the bag.”

And the beat goes on.

matrix41

Today's engineering firms are run by graduates that are great with computers but not experienced with being in the field. Yes, the boring could have been a foot off and the water not found, but the question is, did they do enough?? Also, the city should have a clause in the contract to protect them from additional costs, buy wait! That would have cost some extra money up front, but I can guarantee it's not what they have to pay now!! Thank you Davenport Council, I was running out of ideas on what to spend my little extra money on this year!

quadpi

3 years our street will be closed on Wilkes. The smell has gone away but they will not be back working here for 6 months. I guess because of the water? We residents have zero communication from the city, we just speak to the workers if and when they come by for something.

3 years gives a good amount of time to spruce up the house then sell and move from Davenport.

rando

That tunnel site looks like a homemade above-ground swimming pool. City leaders should abandon the original idea and just go ahead and make this the new West End Public Pool, so they all have at least one accomplishment to to tout in the next election.

rando

I can't find it mentioned in the article: Why is this tunnel being built?

getinvolved

Honestly, I just think it's amazing to hear what engineers can do when a problem arises. It sounds like this is a big one, and I hope it goes well.

MrGadfly

I love reading an article that involves government, and there is the tag line of complaining that says the costs will rise due to red tape and new government regulation! Why does the Times use this in their articles as an excuse for extra costs when it involves local government stories on why things are going up in price, but not when a business closes? Also wouldn't this be a good time to ask our President about the extra costs being put on our local tabs by Government regulations? Wake up people!

retiredopiniongiver

Yes, again --us poor taxpayers, so true! Why not forget about building the "enabling garden" and put it toward the problem! or maybe that so called "vandal proof " restroom at northwest park, they could use that money too!! easier yet, forget about taking all those trips!!! All is not roseie in Davenport! Just last month --- 125 foreclosures , drive on any street---for sale signs on every one. They should quit buying up abandoned downtown buildings ( with our tax-dollar's ) only to not find any buyers, and then pay more for demo!! Once the bike bridge from Harbor road to Credit Island is finished, the bikers will complain about the awful smell of the poop plant ( go down and smell PLEASE, feel sorry for the workers building it) And then the city fathers will have to make a new decision--- should we now move the sewage plant--of course then claim could be --"-Its out of date anyway!! "ya right!!! after all the bridge is brand new-- couldn't move that! Yardbird-- great idea!!!!! maybe a pump and water line could be ran for water co.

Yardbird

Here's an idea: Why not ask Iowa American Water Co. if they would like to pump the water and sell it. It would have to be of cleaner better quality than the Mississippi Mud water they sell us at such high prices. Or better still allow some private company to bottle and sell it?

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