Sewer line depth bellow concrete

[Golestan]

Hi,
We are doing remodeling of a building. I have the plumbing floor plan of existing. How can I find out how far the pipe is bellow the finished floor at any given point. At the floor drains it should be at the depth of the p-trap?

Regards,

Fred

 

[civilperson]

Drill hole in concrete floor and probe to find top of drain pipe.

 

[cvg]

most codes require 1/4" per foot minimum slope on drain lines (approximately 2%) which will give you a rough idea where it might be. Also, check the elevation at the nearest cleanout and then calculate the slope back to the p trap.

 

[cr1973]

Flush a tracer wire down the sewer, then use an above ground locater to trace that wire. Most locaters will give you a depth of what it's tracing, accurate to ~6".

How precise of a depth do you need?

 

[Golestan]

TO: cr1973,

thanks for your reply. The accuracy of +/- 6 in. is good.
I want to lay a new drain pipe and tie into an existing. I am just afraid that at the point of intersection, the new line might end-up to be lower than the existing line. How do do I plan so they intersect and continue to drain.

regards,

 

[civilperson]

Drill at the intersection point of the existing pipe and probe to the top of pipe for an elevation.

 

[cr1973]

You'll have to start at the existing pipe and begin laying your new pipe from there.