i drill 2 inch storm drain bybass holes to main drain storm drains to prevent over flow or back up. you need lots of lube (wd-40 or other lubericant). a good hammer drill. not a black and decker. those low end and cheapper in price thats why many wanna be handyman use them. use a BOSH extreme bulldog, or hilti hammer drill they last longer and are higher in AMPS and power.
1.) mark hole
2.) set depth on hammer drill with side mount marker
3.) spray area of hole with lube
4.) level and align drill( use correct size)
5.) drill for 2-5 secs. then spray lube on hole area and drill bit
remeber to start drill LIVE before touching concrete or cement dont put drill on surface and then start. youll create cracks.