I would rent a core drill and bit.
These drills/bits are readily available at any rental center (maybe even a Big Blue/Orange).
Check that the voltage/amp required to operate is readily available - a 30A 240V extension cord may be needed.
A garden hose to supply water to the bit (keeps it cool and also minimizes dust) may be required also - depending on model available.
You'll probably want a 3 1/2" bit..or something slightly larger than the 3" PVC/ABS OD.
You'll be done in no time at all.
Hitting the rebar is of little concern for such a small hole....but if you are concerned....
Zircon 55586 Metalliscanner 6.0 Deep Scanning Metal Locator $70 +s/h @ amazon.com