One of the common reasons why sewer pipes in San Francisco, gas pipes in San Francisco and water pipes in San Francisco need repairing or replacing is ground shift.
For normal trench digging it is often the case that pneumatic machinery is used.
The plumbing work was a major renovation: new, bigger diameter copper water water piping brought up from street, entire apartment, kitchen, laundry room and both bathrooms, replumbed with copper water line, new gas lines for dryer the stove and firepipe a new hot water heater was in the toilet stalled.
They were on time, on budget were friendly and courteous and cleaned up well after themselves. They did a decent plumbing job. However, in order to get a good plumbing job done, I needed to check their plumbing work every day.