On the morning of Monday, Aug. 24, Tualatin Public Works staff were alerted to an overflowing manhole on 72nd Avenue in Tigard. After arriving on the scene, Tualatin Public Works staff found that the city’s transmission line was rapidly leaking water through a 2-inch hole.
“There was a 2-inch hole blown in the top of the line,” Tualatin Public Works Director Rachel Sykes told Tualatin Life about the line. “It was getting worse by the minute…we figured we needed some pretty quick mobilization.”
Tualatin, which gets its water from the City of Portland, transports that water through 60 miles of transmission pipe, which runs below the city of Tigard and was constructed in the late 1970s.
Sykes explained that the leak couldn’t be plugged until all water was out of the pipe and said city staff sprang into action to begin draining the 3,000-foot-long line. The process of shutting off the line and draining it took about 12 hours.
“That made the timeline of the repair long,” Sykes said. “As we were waiting for the line to drain, we had water in our reservoirs that were able to sustain the city’s water use, but we didn’t have much.”
The city had to divert residents from the transmission line, which was shut off, and start substituting water from the city’s reservoirs, which were lower than normal due to seasonal water scarcity.
Tualatin has at most around 16 million gallons of drinking water on standby in its reservoirs, according to Sykes. While the reservoirs’ capacity is 16 million gallons, the amount of water it’s holding is always lowest in the summertime, and Sykes said that the city could have had “a day plus of water” left.
“The summertime is much more of a concern,” Sykes said. “Our average daily demand is about 4.5 million gallons of water a day, so that’s what we use on an average day…But in the summertime, pretty consistently, our usage doubles.”
Tualatin sent out its first round of water conservation notices on Monday, Aug. 24 at 2 p.m., warning residents and businesses that all of their nonessential water use should be paused until the leak was repaired.
Neighboring agencies and municipalities were quick to assist in whatever ways they could, with staff from Tigard’s Water Division as well as members from the Tualatin Valley Water District traveling out to strengthen response. Rivergrove Water District and the City of Sherwood also supplied the city with water while repairs were in progress.
“We reached out and said, ‘Hey, we’re experiencing this leak and need to make this repair. Could we take some water from you guys to help bolster our supply? Because we don’t know how long this repair is gonna take and we really don’t want to run out of water.’” Sykes said.
The city was able to stop the leak, which originated from a ruptured air relief valve, with a steel cap, and, according to Sykes, the pipe was sealed and functional again by around 7:00 p.m. on Tuesday, Aug. 25.
Sykes explained that, in her five years with the city, she had never seen a similar leak in the city’s transmission line and explained that this leak could raise concerns about the integrity of smaller parts of the transmission line, like air relief valves.
“It was definitely an all hands on deck situation; it’s the most critical water line in our city, it feeds our city the water that we rely on,” Sykes said. “I definitely think that a bit more assessment on some of these smaller little components on the entirety of the transmission line, that could be our Achilles’ heel, is definitely something that we maybe want to start looking into a little bit closer.”
By Wednesday, Aug. 26, the leak had been sealed, and water was being restored to the city reservoirs. Sykes said that the city would continue its call for residents to conserve nonessential water use until Aug. 27.
