What does an upgrade/expansion of an existing onsite wastewater system involve?

An upgrade or expansion of an existing onsite wastewater system specifically involves increasing the system's capacity or accommodating different types of wastes. This means modifying or enhancing an existing system to handle a greater volume of sewage or to treat different kinds of waste that may not have been considered during the original design.

For example, if a household has expanded in size or if there are new regulations regarding waste treatment, the system might need to be expanded to ensure proper functioning and compliance. This could involve adding more treatment units or adjusting the configuration of current components to effectively process the increased load.

The other options do not accurately represent an upgrade or expansion. Installing a new pipeline could be a part of this process but does not encompass the whole concept. Routine maintenance focuses on keeping the system operational and does not imply any modifications to capacity. Lastly, removal of the old system would suggest decommissioning rather than upgrading or expanding the existing functionality. Thus, option B captures the essence of what an upgrade or expansion entails.