HOW FAR MUST BE POWER CABLE FROM THE BENZENE LINE

[bobziva]

My first question is given under title :
(1) How far must be direct buried power cable from the existing benzene pipeline.
My owner is suggesting something what I am not accepting - he want to use abandoned Benzene Pipeline as metal conduit for 600 Volts power cables inside industrial area.
Pipeline is very old, abandoned for many years.
My questions are :
(1) How to know that abandoned benzene pipeline is cleaned up if contractor used pig launcher, and water under pressure ( with no chemicals),can we accept that pipe as cleaned up from the benzene. If not, what kind of cleaning are you suggesting ?
(2) Is there any vapour inside such pipeline, if that pipeline is dry inside and abandoned for many years.

 

[alehman]

I would also be concerned that the pipeline may not be watertight or in good physical condition. Even if clean now, if the pipe has leaked in the past, it is possible benzene may seep back into it from the surrounding soil. Consider inspecting with a camera or pipe wall thickness sensing of some sort.