Sanitary Sewer Program

Assessing Sanitary Sewer Priorities

The Sanitary Sewer Program is based on the 1985 Sanitary Sewer Master Plan and the city’s ongoing maintenance history and television scan (internal inspection) reports. With visual video images and written maintenance information, city staff identifies and assesses priorities of sanitary sewer projects needed to replace sections of the sewer system where the continued cost of maintenance of pipes and manholes would be greater than for replacement.

The Sanitary Sewer Program includes projects in two main categories: increased-capacity projects for lines identified in the master plan as under-capacity, and replacement projects for lines that have deteriorated past the reasonable point of repair. Planned capital improvement projects (CIPs) are intended to reduce infiltration and inflow of stormwater into existing sanitary sewers, reduce deficiencies in aging sanitary sewer collection systems, and build extra-capacity in the system (such as increase the size of underground pipes and manholes) to accommodate new development and redevelopment.

Increased-Capacity Projects

The 1985 Sanitary Sewer Master Plan and a subsequent master plan effort by Clean Water Services in 1995, are used by city staff to determine which projects are necessary to increase capacity of the sewer system to serve new development and in-filling by redevelopment of existing land. The 1985 Sewer Master Plan identified approximately 51,000 lineal feet of undersized sewer pipe.

The City Council has approved funding on a yearly basis for projects to correct the deficiencies identified in the master plan. By the end of FY 1998-1999, approximately 25,600 of the 51,000 total lineal feet of undersized pipe were replaced with properly sized pipe or pipe routing modified to increase system capacity. During FY 1998-1999, a total of 2,973 lineal feet of pipe were installed in this category.


The Sewer Program is funded by the Sewer Fund (502). "Increased-capacity" projects are financed from System Development Charges (SDCs) and "replacement" projects are financed from monthly sewer service charges.

Replacement Projects

The city’s sewer system is comprised of approximately 217 miles of piping ranging in size from 6" to 21".Much of this pipe in older sections of Beaverton is nearing or exceeding fifty years of service. A new program was initiated in FY 1995-96 to fund an ongoing program of replacing deteriorated or failing lines to ensure the integrity of the system in perpetuity. During FY 98/99 a total of 5,080 lineal feet of deteriorated sanitary sewer pipe were replaced.

Mapping and Master Plan

The Sanitary Sewer Master Plan is nearly 15 years old, and does not include a number of areas of the city that have been annexed since the plan was completed. Additionally, with 15 years of internal video inspection of sewer pipes and observations made of the system, city staff have discovered new information which warrants reevaluation of the sewer system master plan. Funds are included in the CIP to complete the process of reviewing and updating the master plan and sanitary sewer mapping.

Additional Resources