I'm currently finishing my basement. I'm putting down sleepers and then ply would over top as a subfloor.

I thought I could use a concrete nail gun to install the sleepers to the concrete; however, my concrete is old and very hard; thus, it is brittle. So the concrete just shatters. I'm having to drill pilot holes and then use concrete nails.

My question is, how deep are sewer mains running in the basement floor? I obviously don't want to drill through the sewer mains running to the street. Is there a standard?

I would have to say no. I assume you are talking about drainage and not supply.

You can consider using construction adhesive, as an alternative. Most floors like the one you want to make end up squeeking or making noise after a while when the wood starts to move. Cement nails can come lose from foot traffic and even road vibration.

I do not like putting wood on basement floors because they hold moisture and hence bacteria and mold. With just a little bit of moisture, you can have the start of an unhealthy situation.

I am a big fan of removable flooring for basements. Carpet tiles can give you a removable option and a certain comfort level. No glue is needed and if one tile becomes stained, you just replace it.If you ever need to pull up the floor due to flooding, it can easily be dried and replaced. Just remember to mark the tiles so you can replace them in the correct postition.