FAQ: Pipeline

What is the water transmission pipeline made of?

The pipeline is welded steel pipe ranging from 48-66 inches in diameter. Steel pipe is typically used in large diameter pipe sizes and where there are high internal pressures. Welded steel pipe is both durable and strong. It has a cement mortar lining and a polyurethane coating. The cement mortar lining protects the steel from corrosion, provides smooth surface to minimize the energy cost to move water, and is a proven material to keep the water clean. The polyurethane coating helps protect the outside of the pipe from corrosion to achieve a long service life for the pipe.

Do you test the pipeline sections as it’s being installed?

Yes. The pipe is tested in multiple ways starting with the joints. First, the welds at the joints are inspected as the pipe is being installed. Second, with double lap welded joints an air test is performed to check for leaks at the joints. Finally, when fully installed the pipe is filled with water and pressure tested above its design working pressure to make sure there are no leaks in any part of the system. This is all supported by constant and thorough inspection and testing of all the different parts of construction associated with the pipe installation to achieve a high quality installation.

Is the pipeline filled with water or left empty until the system is complete?

The pipeline sections will be filled with water after they are built to make sure the cement mortar lining does not dry out. The water inside the pipe will be monitored and may be replaced periodically. When the pipeline is completed (and before water is delivered to homes and business), the line will be disinfected, fresh treated water introduced and then tested for quality.

How will the sections of pipeline be connected?

Each section of pipeline will be welded together at the pipeline joints.

Will the pipeline be under pressure once complete?

All drinking water pipelines are under pressure—completely filled with water (as compared to just being partially full with gravity pipelines like storm drains and sewers). This positive pressure is required to be able to deliver the water to its final destination and with adequate pressure at the taps in homes and for businesses. It also ensures that foreign materials can’t get into the pipe keeping the water supply safe.

Our Reliable Water

Program Timeline

Developing the new Willamette water source will take over a decade.

Willamette Water Supply Program

Willamette Water Supply Program