Hinesville City Council members were briefed Thursday by City Engineer Paul Simonton and Robbie Norby, project manager of underground utilities for public-works contractor CH2MHILL, about a sewage overflow that occurred Oct. 3
According to Simonton, around 9:30 a.m. Friday, Oct. 3, a collection-system operator discovered sewage overflowing from a manhole cover on the force main sewer line that runs from the Hinesville pump station to the Fort Stewart Water Treatment plant. Using a vac-truck, the underground-utilities team determined the source of the overflow was a leak in an air-relief valve on the 24-inch concrete force main.
“That line was installed in the mid-1980s, so it’s more than 30 years old,” Simonton said. “About 2 or 3 million gallons a day of wastewater is pumped from Hinesville to Fort Stewart. The main force (sewer line) is about 5 miles long … It’s a steel cylinder pipe coated with steel-reinforced concrete. There are no isolation valves or redundancies.”
He said one of the 12 air-release valves near the Hinesville pump station was found leaking. The leak was caused by corrosion from hydrogen sulfide, which damaged the air-release and ball valves.
Before Norby and his team could use the vac-truck to pump out the overflow, they first had to ventilate hydrogen gases from the manhole. Norby said they worked on and in the manhole from the time the overflow was discovered until 3:40 a.m. the next day. They missed breakfast and lunch, but had a pizza delivered to them that evening, he said.
“If you want to see guys working really hard, you should have seen these guys,” Guan Ellis, CH2MHILL director, said. “I’ve very proud of them.”
Council members and Mayor Jim Thomas questioned Simonton and Norby about what they found and what it would take to ensure such failures don’t happen again.
Simonton said their short-term plan includes inspecting the other 11 air-release valves in each manhole to determine the condition of the ball valves, and then replace the ones needing replacement. He said the pipe is susceptible to deterioration from sewage-generated gases, including hydrogen sulfide gas, which corrodes the valves. It’s also dangerous to work around, he said.
Another short-term solution he called a “patch” includes inserting valves in the line to allow for isolation of sections, or they could insert valves at each air-release valve.
Simonton said they repaired failed sections of the pipe on Fort Stewart on three previous occasions, and short-term patches do not address pipe integrity or catastrophic failure. A part of any long-term plan would include building redundancy in the system, he said.
Preliminary thoughts, Simonton said, include installing a new force main along Peacock Creek to Fort Stewart. Then, they could investigate the entire length of the old force-main line and use it as a backup if it’s structurally sound.
“We should have a complete evaluation and come back to you by the Nov. 20 council meeting,” he said. “We’ll make our recommendations to you at that time.”
Thomas asked that they include costs for supplementing the old line and costs for building a new one. Emphasizing that the force main is over 30 years old, he told the council members they needed to do something.
In other business, the council approved the revised/updated official zoning map, the final plat of Griffin Park, Phase VII-A, a Continuum of Care renewal application resolution to the U.S. Department of Housing and Urban Development and a memorandum of agreement between Hinesville and the Coastal Regional Commission for hosted geographic-information system services.
Councilors also heard an information item from City Attorney Lennie Darden about proposed ordinance changes to the code to clarify qualifications for the municipal-court judge and creation of an associate municipal-court judge and pro tempore-court judge appointments.
Chief Financial Officer Kim Ryon addressed the council about a special called meeting to adopt the city’s fiscal-year 2015 budget at 2 p.m. Wednesday, Oct. 22. She said the city has received the new tax digest, which does reflect higher tax revenues than expected. This revenue, plus other increases, should enable the council to adopt a balanced budget, she said.