Designing for natural channel reconstructions, Villa Mann Creek

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Detailed Description

Faith Fitzpatrick (U.S. Geological Survey) Tom Slawski (Southeastern Wisconsin Regional Planning Commission) talk about design challenges related to finding reference characteristics for reconstruction more natural channels from stormwater-derived cement lined channels. Stream and wetland construction goes hand-in-hand with roadway construction.

Details

Date Taken:

Length: 03:57:00

Location Taken: WI, US

Transcript

[Music playing]

Faith: What about some of the design 

challenges to a project like this?

Tom: Some of the design challenges as 

part of this whole project were, in 

particular, as you saw downstream it 

was nothing but a concrete line channel 

that was an extreme elevation and with 

a width of about three feet and depth 

of about three inches. So that's not 

the kind of channel we were trying to 

restore. So there were some remnant 

channels that we could use as a 

template full of concrete rubble and 

such, but trying to estimate that 

channel bank flow, which was what we 

designed here at the top of the bank, 

and then we knew our slope, so we had 

to tie into this concrete lining.

We knew our upstream elevation from the 

pipes, so we were able to incorporate 

the top ñ the lower end of the riffle 

and the top end of the riffle 

elevations. These as you can see the 

outside meanders are a little more 

armored but the inside have those point 

bar areas, so they don't require the 

heavy rock. But we're trying to 

incorporate those as well as the pools 

around the bends which are deeper. So 

as you know the grade is controlled 

through these riffles, and it's two 

kinds of channel types that we had as 

cross-sections are a typical riffle and 

typical pool. And then you kind of fill 

in the excavation as the outside 

meanders in the pool.

So the contractors did a fantastic job 

as well as the team in general in 

assisting them and laying out this 

channel and getting it constructed as 

was designed on the plant. One of the 

things too that I think is so important 

as part of our projects is that this 

overall stream design and the overall 

staging is all thought of together 

integrated with the roadway 

construction, everything from the 

timing of the wetland plants, as well 

as the dewatering, and the timing of 

moving equipment and roadways. So 

that's the real advantage with our 

whole team effort with this project.

That includes DOT, DNR, myself, and the 

consultant engineers, so it's what 

makes these projects far more 

successful than they would be without 

everyone talking together.

Faith: Yeah. And then you get to link 

all these different parts together as well.

Tom: Right. Right. So what we're trying 

to do is just trying to get it to 

function properly, and then we know 

there's gonna be adjustments over time. 

But this whole area is designed to 

overbank and reduce erosion on the 

banks, and it will come up slowly as we 

get on the upland side. But that was 

all part of the modeling, and so the 

height of this elevation was 

approximately adjusted for a two-year 

event, but since most of this area is 

fed by storm water pipes, you can see 

water flowing out through there now. 

And you can see the pipes of the 

headwater, you can't get much more 

unnatural, but we're trying to recreate 

a more natural stream given the 

flashiness and through here.

And we're trying to recreate not just 

improved water quality, and the 

potential for fisheries is limited 

right now given we have several miles 

of concrete lining. But from a wildlife 

perspective and from an infiltration of 

stormwater and reducing the total 

suspended solids, and recreation of the 

diverse wetland and upland areas for 

migratory birds and even aesthetics and 

recreation, we're trying to accomplish 

all those things. As well as of course 

flood mitigation and trying to tie in 

and not flood any homes and to try to 

accomplish both these things at the same time.

[Music playing]

[End of Audio]