this construction company guys were nuts. they laid a couragated pipe in sand to be a main water intake for a pumping station.
It had sagged in the center and was losing approx... 1 million gallons a day.
When I got on the job,dove and found out it was a courogated drain farm pipe. I told them it wouldn't work. Also I had them stop running heavy machinery over it when we were diving. They wanted us to seal it up. I was very afraid it was undermined and would colapse with my diver in it. They refused to open up the intake or let us dive from each end. Guy/foreman asked me if I was chicken. You betcha I told him......danger divers don't live long. we did the job and tried to seal it but it was a failure waiting to happen.