Tacoma residents near Pacific Avenue and South 26th Street will wait until spring 2029 for flood relief. Engineers discovered a century-old pipe buried so deep they cannot fully trace its path.

The Tacoma City Council approved a $1.53 million increase to the design contract for the Puyallup Avenue Sewer Utility Replacement Project, as first reported by The News Tribune. The added cost will fund lidar scanning and drone mapping inside a 5-foot-wide stormwater pipe built in 1923 that sits 30 to 50 feet underground, follows old filled-in ravines and crosses beneath private properties.

The increase brings total design spending to $8.63 million for a project now estimated at $90 million overall.

The problem: rocks, concrete chunks and calcium deposits clogging the pipe's joints blocked video inspection and survey equipment. City engineers wrote in a Sept. 10 memo to the council that the pipe holds a large volume of heavy debris requiring extensive manual cleaning before crews can map its exact path. Without that mapping, engineers cannot place the deep entry shafts needed for construction.

The project will replace or rehabilitate roughly 5,000 feet of stormwater and wastewater pipe ranging from 3.5 to 6 feet in diameter. The intersection, a few blocks west of the Tacoma Dome and just west of I-705, sits beneath a train overpass.

The area has flooded repeatedly. Water swamped the intersection in 2019 and again in 2021, when a photo showed people standing on car roofs in at least six inches of water.

The flooding traces back decades. Project manager Jordan Ennis told The News Tribune the intersection was originally built at the bottom of a gulch that filled in alongside development starting in the 1930s.

A Sounder commuter rail extension completed in 2012 lowered a section of road by more than 15 feet, creating a low point where water collects during heavy storms.

The city and Sound Transit agreed the overpass had been a "contributor" to the flooding. In late July, the council unanimously approved a deal, as The News Tribune reported, for Sound Transit to pay the city more than $10 million to take over drainage management for the 1.4-mile Sounder track section. That money will help fund the sewer replacement project, according to Ennis.

Ennis said the $90 million estimate could shift further. "It was understood that scope and costs would be refined as design progresses and decisions are made throughout the project phases," Ennis told The News Tribune.

The project is at 30 percent design completion. IMCO General Construction Inc., based in Ferndale, was awarded the Stage 1 design-build contract in March 2025. Stage 2, covering final design and construction, is expected to begin in early 2027.

The original Sound Transit deal listed a December 2027 completion target. A city spokesperson told The News Tribune on Friday, Oct. 2, that the current estimate is spring 2029.

Separately, the council in August reviewed a proposed condemnation to acquire an 870-square-foot easement at 102–106 Puyallup Ave. and 101 E. 25th St. for the project, according to the Tacoma Weekly. The city failed to reserve an easement when an alley at the property was vacated in 1992, and negotiations with the property owner stalled over fair-market-value compensation.

When the full overhaul is finished, the rebuilt pipes will add drainage capacity to the system, according to Ennis.