The build-up at the edge of a welded seam on a TPO roof membrane is a sure sign of bad welding. These will quickly turn into leaks if not leaking at the very first rain. 

Here, you can see that water sits in this area with no hope of draining. The site is shaded and low, pitched improperly. Taper corrections and built-up curb is recommended as well as adding drainage.

Ponding water and low curb make for bad conditions for overtopping the roof's edge.

If tapered properly and with a built-up curb, we can channel the water to both ends and into a scupper drain attached to a downspout. Recommended that drain pipe is added to this system to a lower grade