Modesto threads the needle with hundreds of feet of sewer pipe laid

Workers spent about a couple of hours Friday threading 675 feet of plastic sewer pipe through a hole underneath the Tuolumne River in south Modesto, part of a roughly $3.2 million upgrade to the city’s sewer system.

This is the first time a city project has used what is called horizontal directional drilling. The drill bore two holes 40 feet below the river – each big enough for an 18-inch-diameter sewer line. Workers drilled the first hole and installed the first sewer line late last year. They installed the second line Friday.

The project has created a bit of a buzz. Engineers from the city as well as other local governments and the Modesto Engineering Club have dropped by to watch at various times, said Pete Kambel, an associate engineer with the city.

“There is almost a mystery factor, a wow factor,” said Modesto Engineering Club president Evangelina Paoluccio in a Thursday interview. “It’s really nice to see a project like that.”

The two sewer lines travel underneath the river between the site of the former Modesto Tallow Plant and the Dryden Park Golf Course. Workers at the golf course Friday sent a smaller pipe through the hole. Workers at the site of the former tallow plant attached the pipe to the sewer line. The pipe then was slowly pulled back, bringing the sewer line with it.

The two sewer lines replace an 18-inch-diameter, concrete-lined sewer line installed in 1970.

Workers used old-school technology when they installed that line. They temporarily dammed the river and dug a trench for the sewer line. That process would raise all sorts of environmental red flags today.

Kambel said workers have a few more months of work on the project before it’s finished. Mozingo Construction of Oakdale is the general contractor. The project’s cost includes construction, engineering and land acquisition. Kambel said the project is being paid for by the city’s wastewater customers.

This story was originally published January 16, 2015 at 4:38 PM with the headline "Modesto threads the needle with hundreds of feet of sewer pipe laid."