Saturday, May 10, 2008

Floodwall Math

This will probably be my last Flood of '08-related post, and hopefully I will return to regularly scheduled blogging.

Flood costs Davenport an estimated $735k

If Davenport were to build a permanent flood wall, I have read it would cost at least $60 million. Even though I think that was from a years-old estimate, and would thereby be too low, I'll use it anyway.

The last major flood was in 2003, 5 years ago. The 2008 flood made the top 10 floods of all time list, which goes back to at least 1868. Judging by that, we only have a flood like this or worse every 14 years or so. However, for the sake of this math I will say that we get a major flood every 3 years.

So we could spend $60,000,000 on a floodwall. Or we could spend $750,000 every three years to build a quick temporary levee and hose off some streets. $60M divided by every 3 years, divided by $750,000 would equal out to it taking 240 years for to "break even" on a floodwall. Somehow I doubt that floodwalls even last 240 years, especially without some annual maintenance. Spending money on maintaining a flood wall just means that it would take even longer to break even. If you change the numbers to a more realistic every-5-years major flood, and $65 million dollar floodwall, it would take 433 years to "pay off" the wall.

This is one situation where I'm definitely an againster. I'm against an expensive floodwall that pushes that water onto someone else, and I'm against spending 240 years worth of flood-fighting money to do it.

Here was LeClaire Park 12 days ago:

And here it is this morning:


Robbie C. said...

i agree in principle with your idea. though i am new to the q.c. so this is the first flood we have dealt with. (maybe i will be singing a different tune in a few years after putting up with this)

but i did want to bring up one point when dealing with the numbers. if davenport was to build a protection system, i would assume a lot of the dollars would be coming from the state and especially the federal government. whereas with this smaller events, its davenport that eats almost all of the cost correct? so perhaps the payoff period wouldn't be quite so bad if the city is only paying 10, 20, 40 percent of the costs or something like that.

also, if its something that needs to be done, the cost just gets higher with inflation. perhaps they could have built a flood wall 40 years ago for a cost of 5 million. that kind of price doesn't look so bad now.

just addin a few thoughts.

pioneer98 said...

I think $60 million is way low. I thought it was more like $100 million.

The state and feds have been providing some money already, in the form of pumps and sewer gates. Having these additions made it cheaper and more effective for Davenport to fight the flood.

The Corps of Engineers takes into consideration the expense to fight the flood, but the main driver for determining if a floodwall should be built or not is the value of the property that the floodwall would protect. Many of the expensive buildings downtown are already protected - the ballpark, Figge, Radisson, transportation center, etc. This is why a flood wall will probably never be built.

Anonymous said...

Davenport Public work employees have to work in shifts to guard the skate park to keep the kids out of the muddy bowl until the river goes down enough for the drain to empty. Maybe "just hose it down" Image with all his security guard experience should volunteer for the job and save us some tax money. Citizen should just be able to put up a closed sign and with enforcement have some respect. Not Davenport.

Anonymous said...

All the arguing is most likely moot, at this point.

Federal money for public works projects like floodwalls is just not going to be forthcoming, ESPECIALLY after the major fiasco and failures of the levee system in New Orleans.

Davenport's policy - to try and move stuff out of the flood plain, flood-proof other closer buildings and utilize pumps and smaller gates - is now becoming the standard everywhere.

The days of the Federal Government giving out multi-millions for big Corps of Engineers projects is over, so this may be a fun debate to have - but is ulitmately fruitless.

Anonymous said...

I like Davenports plan to live with the River rather than building flood walls. If every city up and down the river didn't try to harness the river, everyone would have less problems.

Anonymous said...

If you all would just remember that after the last flood, and we went through all this talk, the COE gave a presentation the council. The cost/benefit ratio just isn’t there to justify building a Flood Control Project for the whole city, mainly because of things that have been stated above (ball park is protected, buildings have been flood proofed (Figge, etc)).

The Corps did say they could protect the area around the water company and the Corps is currently working on that project. The days of the Federal Government giving out multi-millions for big Corps of Engineers projects is NOT over.

P.S. New Orleans levee system failure was NOT a fiasco. You build for a certain level of protection. When that level is exceeded, this is what you get.

Anonymous said...

I didn't think I would be able to find it, but here it is:

At the end of the story it states:

The only floodwall worth the money that is being pursued is one that will protect the Iowa American Water Co., said Perry Hubert, project manager for the Davenport plan.

Overall cost is estimated at $3.5 million, which includes all the studies and construction. Of course, the cost of the wall could go higher if any unforeseen environmental issues arise. Davenport's share of the expense is from 25 percent to 50 percent.

After studying the issue again when the water from the 2001 flood receded, the U.S. Army Corps of Engineers also said that building a floodwall for Davenport would be a huge waste of money.

"We just cannot justify a floodwall along the whole area," Hubert said. "We were able to justify it back in the '80s when the area was economically depressed, there were businesses along the river and it could be used to put people back to work. But that is not the case now."

In the past 20 years, things have changed dramatically, he said.

Many of the businesses that once were on the riverfront have been relocated, he said. Any new structures that have been built are constructed according to FEMA specifications and to the 100-year flood elevation. Additionally, the city is doing a good job of floodplain management, and buying out low-lying properties.

"There are less structures that would be damaged in the event of a flood," Hubert said. "When more damage is prevented, the fewer benefits a flood wall generates."

The reason for the floodwall at the water company, he added, is because of the astronomical cost of supplying water to the area in case Iowa American cannot supply it. "That's where the costs add up," he said.

Construction is tentatively scheduled to begin in 2005, provided all funding is in place, he said.

Anonymous said...

The address got cut off....

Anonymous said...

Anonymous said...

Here's a link to the story 11:15/16/17 tried to post.

All these back-of-the-envelope calculations are pretty useless, given that they don't account for inflation or the cost of financing or other economic factors.

But the bottom line, as many have pointed out, is that there are clearly cheaper and better alternatives to building a flood wall.

Anonymous said...

It's great to see the community finally beginning to understand why we don't need a floodwall for a myriad of reasons.