The job overall was done pretty good. Uriel was the plumber from Crystal Clear Drain and Plumbing that came to do the repair. The leak was due to the position of the wall drain is about 1/2 inch higher than the outlet of garbage disposal. The setup was okay for the last 9 years. Uriel lowered the wall drain by replacing the existing galvanized T-pipe with ABS T-pipe, and replaced all of the piping including the P-trap to the garbage disposal. He had to comeback the second time to change the P-trap from ABS to flexible P-trap due to the vibration when garbage disposal is used causing leak at one of the connector to the P-trap. The garbage disposal is Waste King with 1 HP. The fix seems to be working. We have been using the kitchen sink, garbage disposal and dishwasher as normal for about 1 1/2 weeks now, and no leak detected. The bucket under the P-trap has been dry. I have been checking almost every day. No leak, and now the wall drain is properly positioned (about 1/2 inch lower than the outlet of the garbage disposal). Also, the job was able to be completed without exterior wall being cut open which was suggested by other technician from other company.