Concrete wall in the basement is leaking

Vertical cement wall in the basement (close to the foundation slab) is leaking around where the drain pipes were replaced by somebody long time ago. They poured bad concrete around input / output pipes (drain, etc). Concrete has cracks, and it is leaking. I plan on exposing the cracked concrete by digging the soil outside of the house and then sealing the bad concrete from outside.

1. How do I seal it (after I remove the soil).

2. What materials should I buy?