concrete and pipe

[Al Pike]

How do I deduct 4'' pvc and chairs from a concrete pour? I installed 2-4'' conduits 380' in a 27'' trench.With the chairs I needed about 13'' of concrete to give me 3'' above the pipes.The forman on the job ordered the concrete and came up with 39 yards and we were over about 19.
For future pours any information to help would make my world a better place.Thanks

 

[charlie]

Duplicate post