Specifications include, but are not limited to: A. Bucket machines or rodding machines shall be used very carefully because of their tendency to "hangup on" or "wedge against" the sewer pipe and break it. The machine(s) shall be operated only by experienced and trained operators. The Contractor must possess appropriate licensure for all Work. B. Whenever hydraulically-propelled cleaning tools, high velocity hydro-cleaning equipment (which depend upon water pressure to provide their cleaning force), or any tools which retard the flow of water in the sewer lines are used, precautions shall be taken to ensure that the water pressure does not cause any damage or flooding to public or private property being served by the manhole section involved. C. When using high velocity hydro-cleaning equipment, the Contractor shall take care to use the proper nozzle size so that sand, silt, etc. is not washed from the pipe joint.