We had a very difficult sewer lateral installation in the city of Miami Beach recently. The sewer line was backing up all over the place. We had several pump out trucks on-site to remedy that. The water level was extremely high and the de-watering system could not keep up with the percolation rate. Very strange for this area.
We ended up utilizing an underwater hydraulic chain saw and our own insertion tools to isolate the line underwater while installing the new sewer lateral. The installation worked out perfectly.
On high value commercial work with limited R/W closure we typically send out 2 sewage pump-out trucks, 1 vacuum excavation truck plus all the excavating equipment and support equipment. Below is a pic of the hydraulic chainsaw and vacuum excavator used on a sewer line project.