For several years, Environmental Services has worked to stop sewer overflows to South Ash Creek during wet weather. In 2006, the city installed a temporary bypass pipe on the surface near the creek to prevent overflows. In summer 2013, the city will repair portions of the Ash Creek sewer, remove the temporary pipe and install a permanent sewer line to improve sewer system reliability and stop wet weather overflows to South Ash Creek (see map).

The city’s contractor will use a trenchless repair method for much of the work to minimize construction impacts. There will be about 400 feet of open trench excavation at the west end of the project area to install new pipe that is farther away from the creek. The open trench construction will be on land owned by the City of Portland.

Project Schedule

Work will start in March or April to remove invasive vegetation and trees, and to trim some trees in advance of construction. The city will complete sewer construction this summer.

Post-Construction Revegetation

The Portland Watershed Management Plan identifies revegetation as a key strategy for protecting and improving watershed health. Environmental Services will remove invasive plant species and restore native trees, shrubs and ground cover in the city-owned area that will be disturbed by the sewer construction. Revegetation will include follow-up maintenance and ongoing invasive plant control using manual, mechanical and chemical methods.

Background

The old Tualatin Hills Sanitary Sewer District built the Ash Creek sewer in the 1950s. The eight-inch diameter concrete pipe collects sewage from areas north and south of the creek, and from an area south of Interstate 5. It flows east to west and joins the Clean Water Services collection and treatment system west of the city line.

Although it is a sanitary-only sewer, a considerable amount of stormwater enters the pipe through joints and cracks. Because of that, the sewer is too small to handle wet weather flows.

For More Information

Contact Becky Tillson of Environmental Services at 503-823-2827.