Some Things Should Never Share The Same Space. A Side Sewer Line And A Gas Line Are A Good Example.

There are instances when a gas line inadvertently runs through a side sewer line, usually at a perpendicular angle. When this happens, the situation is called a cross bore.

How could this happen? Seattle side sewer lines were installed when Seattle began developing its neighborhoods. During the installations, the location of the side sewer line was usually mapped and saved by the city.

Gas Lines

The availability of residential gas came later. During gas line installation, some lines were bored using trenchless technology. This means the gas line was pushed through the ground horizontally, with very few holes needing to be dug. Workers first referred to the side sewer maps to locate any existing lines, but not all lines were marked.

If a yard was determined to be clear, the gas work proceeded. If the new gas line met an obstruction, or a sewer line, the boring tool often pushed right through it and kept on going.

Two Lines Meet

This situation alone could exist safely, but when a side sewer line becomes clogged, a technician may attempt to run a cutting tool through the side sewer line to clear it. The tool could cut the gas line and create an extremely dangerous situation.

In most yards, these lines don’t share the same space, but we know that the cross bore situation exists. There is often no indication of the problem until the side sewer line has an issue or a backup. This is when experts are needed.


Whenever clearing a sewer clog or blockage, it is important to be safe and call the experts: Raymark Plumbing & Sewer. Raymark Plumbing & Sewer sends a camera down the side sewer line before work begins. We identify obstructions inside the side sewer line and then determine the best solution to fix the problem.

If any evidence or suggestion of a cross bore is found, we stop work and call PSE. Together we make sure that the line is safe to clear.

Safety First

If you call another sewer company to clear your side sewer line, make sure that they check the sewer line is safe to clear first. No one should send a cutting tool down a line until they know what is in that line.

At Raymark Plumbing & Sewer, we are happy to help with any of your side sewer line needs. We are the experts at sewer problems, work closely with PSE, and are registered side sewer contractors. Call us at (206) 440-9077.

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