Well....the old sewer lines were hollowed out logs apparently....someone figured out how to make a hole in the middle of a tree and used it for a sewer pipe....Off hand, can’t imagine wanting to do that…
And while you mention the 4” PVC pipe…but not the size of the hollowed log, or how it was hollowed, keeping the entire outer part of the log intact, or how long it is…why? Really, they want a LOG to be part of the device to carry human waste and paper and undissolved drugs?
Connecting a pvc pipe to the end of a log or another device seemingly would require a cupeling and cement glue applicable to both devices.
And going beyond the construction site itself to replace city government property is not on any contractor's agenda.