The special hand-made stairway to our garage attic at its 5/8 height is almost complete (picture 1). The only work left out is the supports for the stairway on its right (against the wall). To support it properly, I need to find out the vertical stud locations inside the wall. To this end, I used the drill on the wall to see whether it hits any stud. After several trials, I felt that I hit something. I thought it was a plastic electrical box. Suddenly, there was water on the garage floor, a lot of. Immediately, I knew I hit the water drain line somewhere inside the wall.
To learn more about what is really inside. I cut open a ~ L-shape opening. Of course, there was a drilled hole on the white plastic drain pipe (picture 2) as well as two studs.
To fix the leak, I used a half-inch-height section of the identical pipe (the only left-over pipe I have.) I cut out an 90 degree section to form a 270 degree ring with enough spring clamping force when attached to the damaged pipe. After gluing it (picture 3, purple color is from the primer liquid) and it works fine – no leaks.
Tomorrow, I am going to finish the entire stairway to conclude the Phase I work. The attic floor & the reinforcement of the vertical drop beams attached to the garage ceiling will then be completed in next Winter.