Junction Box & Pre-Cast Manhole Pipe Question

[JoelTXCive]

We are designing a Cast in Place stormwater junction that will have a top of box about 8ft below grade.

If possible, I would like the contractor to use PRE-CAST ASTM C478 Manhole Sections for the junctions boxes' risers.

My question is..... I do not know how to define the male/female geometry for the Pre-cast pipes' connection to the CIP box? (see below photo)

If this was a horizontal connection, we would have the last pipe section contain exposed rebar ends, and then do a closure pour. I don't think I can do that for a vertical connection.

Question: Is the actual male/female geometry proprietary for each pre-cast company? Or, is it defined in a standard somewhere? (I don't see it in ASTM C478)

Worst case scenario, I can do a Cast in place riser, but it seemed like it might be easier to do precast.

Thank you in advance.

 

[JedClampett]

If I understand your question, I think you'd be better off with either a male/male first piece of pipe, a male/plain end first piece of pipe or a groove slightly larger than the pipe OD formed in the top. Seal the joint with Ram-Nek or hydraulic cement. If you have a large internal pipe pressure, you've got other issues.
The contractor will likely wait for the pipe to get there to pour the top, so they'll have a template.

 

[HTURKAK]

Why cast in place junction box? You may plan precast bottom bowl , top slab and circular shafts.. Construction of pc junction at outside of trench and placing to the correct location with is better since the working conditions in a trench is more hostile.

The PC manufacturers should have flat/ male ring option or you may choose the female at bottom laid on groove.

I found at web the following picture to see the top slab- shaft joint.

 

[Settingsun]

Is a collar pour an option? Just sit the riser on top and pour around it.

 

[dcornelius]

How many pipes will come into the "box"? What are the sizes in and out?

 

[JoelTXCive]

HTurkak - When I saw these boxes, I suggested they do pre-cast, but the land civil engineers said, "No, they wanted cast in place for the junction boxes." (I have no idea the reason, but it's their project and I'm support staff on this one.)

Dcornelius - I'll check tomorrow in the morning on the pipes, but we have several junction boxes with different pipe setups. I'm trying to make them all the same geometry, but different holes for pipes or RCB's. I think the largest RCB is a 6x6 or 7x7

Steveh49 - I liked your idea of a collar pour combined with JedClampett's idea of a flat plain pipe riser pipe end. I came up with the below detail... What do you think?