A sinkhole on Water Street following the break of a 14-inch sewer main in late December.

Photo courtesy of the city of Port Townsend

Port Townsend staff will soon have an inspection camera at their disposal, or rather in their disposal system.

City councilmembers unanimously approved a resolution Monday to inspect approximately 10,000 lineal feet of asbestos concrete sewer pipe in Port Townsend’s sewer main. The move follows the failure of a portion of the pipe  near Water and Gaines streets in late December, which caused sinkholes and sewage to overflow in the area.

The work will cost up to $45,000, and the city will utilize the services of a video inspection firm as well as RH2 Engineering, a Bothell-based engineering firm, if any pipe rehabilitation is needed after the probe.

The portion of the sewer main that collapsed was built in the 1960s and appeared to be heavily deteriorated by hydrogen sulfide gas (commonly referred to as sewer gas), which corroded the asbestos concrete pipe, according to Public Works Director Steve King.

“The sulfuric acid that ate out the top of the pipe, we need to figure out to what extent that has impacted [the pipe],” King said during Monday’s city council meeting. “We’re going to focus in areas where impact is significant. Water Street, Sims Way, downtown, those are the places where it’s really challenging to dig a 12-foot hole in the street.”

Considering the potential damage to other pipes in the area, the city will inspect specific sections of city sewage pipes. 

The purpose of the probe is to inspect other pipe of a similar age and type for signs of deterioration.

What the city finds from the video inspection will determine the next steps. If pipe rehabilitation is necessary, the city will work with RH2 Engineering to decide what form of rehabilitation is needed.

“They will look at the camera video footage and help us select the right solution for rehabilitating the pipes,” King said.

One of the primary ways to fix deteriorated pipe is called cured-in-place pipe lining. The method involves inserting a flexible liner inside the pipe, inflating it to fill the deteriorated pipe, then exposing the liner to heat to dry and harden. The technique essentially forms a smooth surface inside the pipe to restore the aging infrastructure to near-new condition without full replacement.

RH2 Engineering has assisted nearby areas such as Poulsbo and other parts of Kitsap County with similar tasks.

Councilmember Owen Rowe inquired about the testing used to demonstrate that Port Townsend’s drinking water is not being affected by its own asbestos piping. King clarified that the city’s contaminate level is well below any harmful levels.

“We did a little research … Our level of asbestos in the water, the contaminate level that requires action is 7 million fibers per liter, and our level of fibers per liter is around 0.1, so we’re way under,” King said.