Al wrote:

A maple tree approximately 3 feet in diameter
has grown over a waste water drain. Roto-
rooter could not get through.

My idea is to dig down and install a bypass
around the maple tree.

How far out from the tree should the bypass
go? Is it going to work?

Yes, it will work.
Use 45's, not 90's to form the loop.

Things you'll have to consider though:

If the sewers are deep where you live,
that will be a LOT of digging/trenching
thru heavy root infestation.

If there wasn't much slope to begin with in
the lateral, you'll have to lay the pipe very
carefully to avoid low spots and you'll wind
up with precious little slope to boot.

In olden times, the water service line was
often laid in the same trench with the sewer
(although may be on a "shelf"). You might
get assistance from the utility in locating.
During actual digging, keep a metal detector handy.

The pipe has to be well-supported by firm earth
so that it doesn't droop as time goes by.

You'll probably need a permit for the work
(depending). They may dictate what materials
you are allowed to use.

I would install a Cleanout TEE at the top of
the loop (nearest house) and stub it up to
ground level.

Jim