An upgrade of the OWTS may be required for any alteration, modification, remodel, or repair of any structure on the property that involves the addition of bedroom equivalents or plumbing fixture units which increases the wastewater load to the existing OWTS. In addition, an upgrade may be required for any modification to an existing onsite wastewater treatment system (septic system or an inspection of the OWTS shows that the system is failing, an upgrade may be required to protect the environment, and public health.