Levelling Underground Buiding Soil Pipe Placement to Ensure Correct Invert

[mahara7a]

Greetings to respected engineers.

For an early note, I'm only recently involve and new in underground building sewage plumbing. I have a question on how to clearly interpret manhole invert level on site. Let say, I have soil pipes directed to external building manhole and based on civil drawing its invert levels are given as so and so. I always have a hard time to identify if our pipe are correctly level before pouring the concrete. My concern is always that we do not want that the soil pipes which is the inlet of the manhole is lower than the outlet of the manhole. Is there any rule of thumb on how to interpret invert level? Perhaps if there is any calculation so that I always can ensure our pipe is correctly leveled and necessary pipe sleeving can be done. Refer attached picture of what Im trying to convey. The yellow lines represent the soil pipe that we want to install. The length of the pipe is for example only. The invert level given is an example only. Sometimes we do works with manhole that have shallow depth.

Thanks and sorry for the long post.

 

[LittleInch]

They look like very shallow pipes.

Invert level is simply the level at the bottom of the inside of the pipe. There's not much to interpret here

It's not clear from your attachment which pipe is being referred to at K1,2,& 3, but I'm not quite sure what you're asking about.

And your post isn't long - We like detail.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[AgMechEngr]

Invert levels are checked and set using surveying instruments like transits or auto-levels.

 

[bimr]

The invert is the bottom of the inside of the pipe. We set the pipe inverts during design and the Contractor is supposed to install the piping at those invert elevations. Piping is supposed to be rigid enough so there is no sag between the manhole inverts.

 

[mahara7a]

Littleinch:
Thanks for the reply. K1, K2 and K3 refer to the manhole. The yellow pipe are flowing to the manhole. As in the attached picture, there are details of the manhole such as invert level, manhole depth and etc. What is the reference of this measurement and how to check on site to ensure that the yellow pipe entering the manhole is located higher than the outlet of the manhole.

AgMechEngr & bimr:
Thanks for the replies. How can I know what the reference of the invert level based on? Is it based on Floor Finished Level, Ceiling, apron slab or something determined on common practice? Excuse my lack of knowledge in level surveying.

 

[LittleInch]

The reference height will be noted in the drawing or in a note.

It also gives the level of the "platform" so you could work back from that if this is already built.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[bimr]

Yes, the plans should always have a reference elevation on them.