Sewer System Evaluation Studies

OWASA periodically completes comprehensive Sewer System Evaluation Surveys (SSES) to systematically identify and prioritize the need for improvements to the community's wastewater collection system (sewer lines). SSES projects are done on a basin-by-basin approach (Bolin Creek, Booker Creek, Little Creek, Morgan Creek).

We have a GIS-based prioritization procedure that ranks sewer line replacement and rehabilitation needs based on factors such as pipe age, material, corrosion potential, number of customers affected, criticality, and condition.

Sewer lines are repaired or replaced when needed to:

  • accommodate present wastewater flows and ensure structural integrity;
  • address sources of stormwater inflow and groundwater infiltration; and
  • accommodate future flows resulting from growth in new areas and infill/redevelopment at higher densities than currently exist.

Where feasible and cost-effective, lines can be repaired using trenchless (non-digging) technologies, such as Cured-in-Place lining and pipe-bursting. If necessary, sewer lines are removed from service and replaced with new pipes.