HEC-RAS required cross sections for CLOMR 1

[dlnva350]

I'm working on a HEC-RAS model to support a CLOMR application. Our design proposes a grandstand at the west end zone of a football field . The end zone is currently in the 100-YR flood plain. A stream runs adjacent to the end zone and the grandstand will be between the end zone and the stream.

There are about 15 column lines for the grandstand that will be in the floodzone. Here's the question: Each line consists of 7 columns, each 1' wide. I've cut a cross section at the US and DS end of the grandstand area, adding the 7 columns to each section as obstructions. It's my understanding that HEC-RAS will view the obstructions as 7 continuous obstructions. Is this sufficient? To model each column line would seem to be excessive to me.
-Thank you

 

[RWF7437]

A sketch would help !


"The end zone is currently in the 100-YR flood plain"

Is it in the flood plain fringe or is it in the floodway ?
Can the grandstand float or drift ?
What are the flow velocities likely to be ?

"A stream runs adjacent to the end zone and the grandstand will be between the end zone and the stream. "

Does the stream run parallel to the goal line, at some angle to the goal line or perpendicular to the goal line ?

What are the plan dimensions of the grandstand ?
Can the grandstand be treated as one obstruction ( if clogged by floating and drifting debris ) ?

What are you attempting to demonstrate with your HEC-RAS analysis ?

Do you have any other options, such as moving the football field ?

 

[MattZ99]

I would think what you proposed should be sufficient for a CLOMR submittal. I think it would be important to account for what is providing an obstruction to flow. Be sure to provide a brief note in the cross section editor to explain what you are trying to represent and if possible, attach a picture or construction drawing either in the HEC-RAS model or submit with your CLOMR materials.

 

[froude]

I think Matt definitely has the right idea here. I believe that you have correctly identified that the grandstand can be modeled as an obstruction, and as long as you provide documentation (via a narrative, workmap, photo, etc.) as to what the obstruction is, you should be good to go! good luck!