On Jul 25, 6:23*pm, "MiamiCuse" wrote:
"Joe" wrote in message

...
On Jul 25, 4:36 pm, "MiamiCuse" wrote:

snip
Third link shows clean out on the left with letters 'C.O.'.If that is
original marking it could mean "clean out", so concentrating on that
one seems best place to start. A diamond hole saw from *Harbor Freight
would be a low cost way to get through the concrete with little danger
of drilling into something vital.
Joe

You mean to get a 4" hole saw and saw on the outside of these 4" holes or
saw the inside of the hole?

A 1" diamond hole saw might work best, taking out bite sizes chunks
without whaling away at the underlying structures. With some finesse,
a hidden plug ought to show up. Good luck.

Joe