Combined pond and UG chambers

[Anonymous]

Is there any way to properly model a pond with a section of underground chambers attached to it?

I already have a small "upper pond" draining to a larger "lower pond" but need to model more storage. I have hoped to supplement my lower pond with several 36" CMP barrels. I can not find a way to properly model the system.

Is there any way to combine a pond and pipes without going through the "manual" stage storage chart?

Thanks,
Nate

[annw2]

Hydrograph does have a rudimentary chamber option for underground basins. It assumes simple pipe with options for header and stone encasement. For small sites with underground chambers, I prefer HydroCAD. Haestad Pond Pak would be another option.

p58 of the 2007 manual describes underground chambers with open contour pond above, but I never figured out how to do it.

If you have an odd size underground basin with just some underground storage or the brick shaped blocks, I calculate the total storage manually, then enter as contours and adjust percent void to match the total volume.

The most important thing for me would be to verify that underground chambers allows infiltration out of the bottom. I do most of my routing to obtain a volume infiltrated value for NPDES permits.

[Anonymous]

I have used the chambers option before for several sites with good results.

I see that page 58 does indicate that up to 2 volume entries can be combined into one pond. However, it is not very clear on how to do it. Now that I know it is possible, I'll keep trying.

I had considered manual entry on the table but that is not nearly as easy to edit as chambers / contours are.

My situation is fairly unique. I have a bioretention "pond" collecting the first flush runoff to treat water quality. Larger events over top the bioretention area and flow into the pond for controlled release. The municipality dictates the release of the 1-year storm over 24 hours. In effect, this increase the size of the required pond by 1,400 cf. I ran out of space for the pond and had to make it up underground.

Thanks again for the direction to p58.

[Anonymous]

OK I got it to work.... sorta. It did allow me to use UG chambers with contours but the chambers had to be completely beneath the contours. That does not fit my situation so it looks like I will have to perform the calculations and fill in the manual entry table.

Not looking forward to that but I guess it will work.

Does HydroCAD allow use of UG chambers in combination with pond contours?

[Anonymous]

HydroCAD allows any combination of storage options in each pond. Just use a separate line on the Storage tab to define each volume. The pond storage is the sum of all storage volumes. Storage elements can also be embedded inside one another, such as chambers within a stone bed.

[annw2]

Revisting this issue again and not working.

I have an above ground basin with pipes entering into it at a flat slope.  I wanted to add the pipe storage volume to the pond volume, but 2014 says the contours have to be ABOVE the pipe elevations.  That is the opposite of what I want.

Pulling out either my old spreadsheet or HydroCAD.