The city of Dunwoody is considering raising storm water fees to pay for improvements to its aging pipes.

Dunwoody Public Works Director Michael Smith recommends the city spend $900,000 to $1 million each year for pipe replacement. That would increase the annual storm water fee for most homeowners to about $69 from about $48.

Smith told members of Dunwoody City Council at their Feb. 13 meeting that over the past two years, the Public Works Department has conducted a survey of the city’s storm water system. He said the department learned that 60 percent of the pipes in the city are more than 35 years old, which is past their typical service life. Roughly 70 percent of the city’s storm water system is corrugated metal pipes, he said.

“Metal pipe corrodes and doesn’t last as long as other materials like concrete,” Smith said.

Corroded pipes lead to leaks, which wash away dirt and cause sinkholes. “Sinkholes are common in a lot of the calls we get,” Smith said.

Smith said it would cost $87 million to completely replace the system. The city has an annual budget of $525,000 for pipe replacement, which Smith said is too low to keep up with necessary repairs.

“Right now it’s kind of like triage in an emergency room,” Smith said. “We have to look at what’s the most critical to get done.”