Culvert river crossing 2

[JohnWeal]

We are designing a large sewage collection culvert system where the culvert size is a twin 3m high by 3m deep.

Please can anyone advise if there are any standard designs available. I am concerned not just with the physical size and installation aspects of the projects, but also the tendency for the sewage to collect at the low point.

Regards

 

[EireChch]

2 no of 3m wide x 3m high culverts beneath a river. Sounds challenging.

What are the soils? Alluvial soft souls o guess.

How wide is the river? How deep beneath the river bed do you need to be?

I've heard about Culvert jacking as an option. I've never used it or seen it being used but from what I've seen online you would have cutting blade on the front of your box section. Dig a pit and then lower the culverts in a jack them off the back wall of the pit. 3x3m would be tight to get a small excactor in to remove the soil. I'd say there are people here that know Moore about it than I do, so please correct me if I am wrong[pre][/pre]


Re the low point, i presume it's a gravity system? I would ensure that there is no low point beneath the river portion. With a rising main you can have low points depending on the topography. These low points require flushing wells for maintence to clear out the solids that sit in the low point. I imagine it would he te same fi you have a low point in your culvert.

 

[cvg]

river crossings for sewage are generally either siphoned or force mains. you really cant do it with a concrete box section as they do not make a precast box with a joint/gasket that can handle water pressure. on the other hand, there are plenty of round pipe options that can handle both jacking forces and water pressure. suggest you switch to a round pipe or series of pipes. unless this is a dry riverbed, you will need to jack and bore / microtunnel under the river, below the potential scour depth. or potentially directional drill. call a pipe jacking contractor for some help with the installation.

 

[JohnWeal]

Thank you for the replies will consider all these comments to progress the design.

 

[bimr]

Review the design shown in Mecalf & Eddy "Collection and Pumping of Wastewater: as shown in the link:

http://www.eng-tips.com/viewthread.cfm?qid=410405