Aging infrastructure, fluctuating temps taking toll on Dover’s water mains

DOVER — Water mains within the city of Dover seemed to be spewing water like geysers between Dec. 1 and Jan. 16.

Jason Lyon, assistant director of Public Works for the city of Dover, said there were 11 water main breaks that occurred within the city’s water system over that six-week span, which was atypical.

Mr. Lyon addressed the Utility Committee at the Council Committee of the Whole at City Hall last week to inform its members what Public Works believed has been taking place among Dover’s aging water main infrastructure recently.

“During a six-week stretch, we had 11 water main breaks in the city of Dover, and they came in all sizes, shapes and colors throughout the entire city,” Mr. Lyon said. “The goal is to (find out) how these water main breaks occur and what could have been the cause of these water main breaks, although it’s very difficult to pinpoint the exact reason.

“Water main breaks are kind of spread out over town. There’s not a significant area that’s seeing this more than others and it just goes to show you that the water main breaks in general are very unpredictable. They can happen anywhere to any sort of material.”

The first of the water main breaks occurred on Dec. 6, 2019, at 310 Walker Road.

“On December 5th there was a high-speed (police) chase with a vehicle down Walker Road and the driver tried to make a turn on Lakewood Place and took out a fire hydrant,” said Mr. Lyon. “On the face of that it looks fine because we had to replace a fire hydrant, but there are long-lasting effects from that because that fire hydrant is obviously connected to the water main system and when that stress of the fire hydrant is pushed over, it does stress to the pipe.

“When that stress hits the water main, it just makes everything loosen up. That was the reason for the first two water main breaks.”

Mr. Lyon attributed the next nine water main breaks to fluctuating temperatures and the age of Dover’s water mains and the materials they are made of.

Pipe dimensions, pressure capacity and stiffness are all affected by temperature changes. Pipes also expand with increasing temperatures and contract with decreasing temperatures, which weakens them. Freezing and thawing soils can cause shift and that’s why an increase in water main breaks usually occur at the beginning and end of the winter season.

Mr. Lyon noted that 47 percent of the city’s water mains are more than 50 years old.

The average age of the water mains that broke during the six-week span was 56 years old, including an 80-year-old water main that broke at 445 E. Loockerman St. on Dec. 22. They were all constructed of cast iron pipe, which is more susceptible to external pressures such as extreme temperature changes.

“We attribute these to temperature, age and the type of material that the water main is made of,” Mr. Lyon said. “The remaining nine (water main breaks) we believe are due to temperature fluctuation. We’ve had very up and down temperatures and, historically, once we get to a cold temperature, it stays that way and the soils don’t expand or contract. It just kind of stays in the same composition, and the pipes like that.

“But when it goes up and down and you get some cold snaps and a little bit warmer days, that’s when you have this kind of contraction that occurs.”

The water main breaks can occur at any time, as a 52-year-old one burst at 691 N. DuPont Highway on Christmas Day.

The recent spree of water main breaks could just be an anomaly, considering the national average is for 14 breaks for 100 miles of water main per year. The city of Dover’s average over the past decade has been 7.1 breaks for 100 miles of water main per year, however, that number is trending towards having 13 breaks this year.

Mr. Lyon said a typical in-house repair cost for a broken water main for the city of Dover is $3,500 (less street repair) and added that the city usually receives contractor assistance for main breaks in areas such as highways that require additional equipment (i.e. trench box, maintenance of traffic) and those cost around $12,000 (less street repair).

The city of Dover has replaced 0.39 miles of water mains per year over the past five years.

City Manager Donna Mitchell said those numbers will need to increase in the coming years.

“We do have a water/wastewater rate increase (coming up),” Mrs. Mitchell said. “I’m working on those numbers to bring back in the February (City Council meeting), so you will see what those look like, but we are projecting a rate increase to help us try to catch up on some of this. We haven’t had water/wastewater rate increases for about 10 years.”