I am trying to repair my backpack whose straps wore down. I decided to replace them with bands of heavy duty plastic-like fabric that I found. Unfortunately, it is very hard for me to push a sewing needle through the bands. I can do it if I grip the needle with pliers and apply all my force. I...

A colleague works in a closed (no public access) watershed and came across this culvert today. These smooth "tracks" down the center of the culvert are something we have never seen before. Any idea what they may be for? Some details that may afford clues: Culvert installation date is unknown (...