WARNING: This page is about a different car, the 2019 Buick Cascada, 2018 Buick Cascada, and 2017 Buick Cascada. However, it is still accessible from the selected car via links, so may be relevant.
Remove the water pump inlet pipe bolt (4).
Remove the water pump inlet pipe (3).
Remove and DISCARD the 2 water pump inlet pipe seals (1, 2).