You have a supply line entering your home and a 3" sleeve was used? Wow...I don't even know what to say to that.
If you have a cinder block wall, then yes sealing it from the outside would be a good idea. If you have a solid concrete footing, then sealing it from outside is not necessary.
However in either case, you probably need to address your perimeter drainage and landscaping to ensure storm water is being drained off away from your home like it should be.