A year after construction began on the North Creek Interceptor sewer system, the county Wastewater Treatment Division is planning on allocating nearly $23 million to finish upgrading the nearly 50-year-old infrastructure.

Stretching from around 208 Street Southeast in Snohomish County down to 228 Street in Bothell, the sewer system is projected to serve 105,000 people by 2060, according to the Wastewater Treatment Division.

Constructed in 1970, the current pipe system has been prone to overflowing during storms, causing some manholes to overflow, spilling diluted sewage and rainwater onto surface streets.

The larger new pipes, constructed with reinforced fiberglass resin, both expand capacity and replace older cracked pipes, said Wastewater Treatment Division spokesperson Annie Kolb-Nelson.

“The new lines will serve the area for the next four or five decades,” she said. “(There’s) really no new technology, just bigger pipes and just more capacity, and newer pipes so that they’re going to operate more reliably in the future.”

The entire North Creek Interceptor project will cost around $52 million, replace around 10,000 feet of piping and should be finished by this fall, Kolb-Nelson said.

Various techniques will be used as construction ramps, including underground tunneling and above ground trench digging, which Kolb-Nelson said could disrupt traffic in part of the city.

“There’s been construction in neighborhoods, and some of that has impacted people with some traffic detours,” she said.

Updates on road closures are available at kingcounty.gov/NCI.