Corrosion in city sewer main could have costly fix

Corrosion issues in a sewer force main that services the west side of Newton is forcing the city to address the issue. Newton Public Works Director Jody Rhone recently addressed city council about the problem with the southwest pump station force main and presented possible solutions to stop the leaks.

The largest area of concern comes in the first 3,200 feet of the force main. That area is located south of Noble Auto Group and continues east near West 24th Avenue. The 16-inch iron force main was constructed in 1985 and is used to facilitate water runoff and sewage through the line when gravity flow is not sufficient.

“In 2014, we had a leak in this line. We weren’t sure what was going on with it, if it was an anomaly or if there was a bad section of pipe,” Rhone said. “We thought maybe it was a defective pipe or maybe it had been hit with a rock or something with the installation, we weren’t sure what was going on, but it seemed like a fairly isolated incident.”

Rhone said the city looked at the pipe surrounding the area and it all appeared to be in very good shape. Despite that, during the next few months another leak popped up at an additional location.

“We did some spot repairs with materials that are made to take care of a isolated spot, but we continually had more leaks,” Rhone said.

After eight more leaks were detected in the pipe, Rhone said it was time to look a little further into what was happening with the force main. An investigation into the area showed there appeared to be corrosion from the exterior of the pipe to the interior.

“We have had the soil analyzed and there are corrosive soils in this location, especially in the ground in the first 3,200 feet because of the terrain,” Rhone said. “We know what was old coal mines at one time.”

The land this pipe was laid in has had major grading work completed since 1985, causing the line to sit 20 feet deep in some places. Typically, a pipe of this standard is expected to be in use for 90 to 100 years. With only 30 years having gone by since it was put into service, Rhone said he wasn’t expecting to deal with any issues.

Rhone did investigate the possibility of faulty installation or an issue with the pipe itself. The same pipe was used into additional locations across Newton, the Southeast Force Main near the speedway and the Lambs Grove Force Main.

No other leaks have been detected in any other areas or even in the second half of the southwest force main, Rhone said.

“From what we have seen and we have exposed large sections of this, it does not appear to be faulty installation,” Rhone said. “We are finding perfectly good sections of pipe where you can still see the chalk writing of section numbers on it.”

In the short term, the city has been replacing small sections of the pipe that have had leaks with C900 PVC pipe, the new industry standard.

“When you replace a 20 foot section, how much does that typically cost?” councilman Craig Trotter asked.

Rhone said the pipe is $70 per foot with additional excavation costs, as well. So far, a few hundred feet have been completed in area but the Rhone said the entire 3,200 foot section needs addressed.

“We’ve hired Fox Engineering to do a design and figure out how we are going to deal with this problem,” Rhone said. “We have looked at several different options as far as slip lining segments of this, replacing segments, completely rerouting the whole main to get it out of the corrosive areas.”

The engineering firm presented three options ranging from $600,000 to $1.6 million for a completely new force main and alignment for the entire 7,100 feet of line. Rhone said he is pursuing the option of replacing the first 3,200 feet were the leaks have been taking place.

“We are going to have to pursue some kind of corrective action, whatever it may be,” Rhone said.

The issue will need to be considered by city council at a future meeting for potential action.

Contact Jamee A. Pierson at 641-792-3121 ext. 6534 or jpierson@newtondailynews.com