When heavy rains arrive in the city, public utilities workers often start trudging through backyards and city parks along Crabtree Creek looking for trouble.
They head to places where so much excess rainwater enters the wastewater sewer lines that it floods the pipes and causes water to spill out of manholes.
Once they reach the hot spots, the workers monitor how long the flow lasts and how much water has escaped, and they clean up the mess. But there’s nothing they can do to stop what’s known as a sanitary sewer overflow, a public health and water quality threat.
The city says a new major pipeline in the Crabtree Basin will help curb the problem.
At 54 inches in diameter, the 21,000-foot line will run along Crabtree Creek from just outside the Beltline near Glenwood Avenue to just east of Capital Boulevard a bit south of the Beltline.
Construction of the $30 million to $35 million pipeline is slated to kick off this spring and last until 2018, bringing with it rolling road and greenway closures.
It is one portion of a $75 million to $80 million project known as the Crabtree Basin Wastewater System Conveyance Improvements, a mouthful that the city of Raleigh has rebranded as the “Crabtree Pipeline” as part of a public information campaign.
The project has a dedicated website ( crabtreepipeline.com), phone number, email and Twitter hashtag. All residents within 1,500 feet of the project are expected to receive letters in the coming weeks with information about it.
“We’re trying to make it as easy as we can for citizens to get the information,” said Eileen Navarrete, a construction project administrator.
The city already has completed two parts of the project: repairs to the existing pipeline and 20,000 feet of new pipeline running from Capital Boulevard to the Beltline’s U.S. 64/264 bypass ramp.
City officials know the next phase will cause far more disruption and are trying to prepare for it.
“We’ve been very clear with people when talking about this project that it’s not going to be pleasant. We’re not trying to sugarcoat anything or make people think that there aren’t going to be any impacts from this project, because there will be,” Navarrete told the city council earlier this month.
The construction requires crews to dig as far as 20 to 30 feet underground. Much of the construction will take place on city property, but there will be construction in residential neighborhoods.
The project has two main components: Crews will dig open trenches to lay pipe, and they also will tunnel, mostly under major roads.
There are eight tunneling locations along the route, and that part of the project is expected to begin in the spring and last 20 months.
The trench construction will begin this fall and last 24 months. The project will move from east to west.
The exact dates for road and greenway closures won’t be set until the construction contracts are finalized, but one of the earliest and most significant closures will be on portions of Hodges Street between Capital Boulevard and Wake Forest Road.
The first closure will likely be this summer, for two months. A second will occur in early 2016 for six months.
During road closures, detours will be in place, and all businesses will remain open.
The Crabtree Creek drainage basin includes about 93,000 acres in Wake and Durham counties.
About 20 million gallons of waste flow through the basin to a wastewater treatment plant daily, almost half of the volume that arrives there on an average day.
Two 36-inch pipes run along either side of the creek and are the backbone of the wastewater collection system.
The pipes are designed to accommodate some excess rainwater, but when rainy conditions combine with peak wastewater flow times – a few hours after most people wake up or go to to bed – the system can become overwhelmed.
In addition to heading off overflows, the improvements are expected to accommodate future projected wastewater flows as Raleigh’s population grows.
“The long-term benefits for the city outweigh the temporary impacts,” Navarrete said. “We’re hopeful that people will understand it’s really, really necessary.”