Requires 1/3 the operational budget to maintain

All sewage conveyance systems require operation and maintenance programs for proper functioning. The normal cycle for flushing, inspection, and repair for a historic gravity sewer is usually three to five years; maintenance frequency increases as the historic sewer system ages. As the joints in the maintenance holes and piping deteriorate, inflow and infiltration (I/I) increase. In many instances, older systems have over 50% flow attributable to infiltration (usually set at 90 litres per person per day or ~ 20%).

The annual cost of operating a historic gravity sewer system and a Small Bore Sewer™ system will vary from location to location, but values listed for small to medium sized communities in Ontario provide a medium range of cost as set out in the table below; this table is based upon new comparative systems, and provides an allowance for repair and replacement reserves, beyond the annual operational requirements. The estimate is for a typical household in a communal environment in rural Ontario - maintenance programs and costs are outlined below.

 (Typical household population = 3 persons/home)