This slab had a slope toward the building and with every hard rain water would flood into the doors. We cut a channel of concrete out, dropped a drain in with a lower grade, and sloped the patch down to it.
Turn out:
Start:
Click this link to see more photos:
https://drive.google.com/drive/folders/1TKEaOb8j_3ggXoIPez-9Nn8ktyzEpe65?usp=sharing