Chemical corrodes city pipes

Published in the Argus Observer February 4, 2015.

Many area residents are familiar with the rotten egg smell that tends to waft from Ontario’s water and, though it may cause you to turn up your nose, the chemical responsible for the infamous odor has more on its agenda than simply an assault to the senses.

Hydrogen sulfide, or H2S, is highly acidic and has been wreaking havoc on Ontario’s sewer lines for many years, causing the concrete pipes and manholes to corrode.  As well as corrosion, the gas is toxic above the level of 500 parts per million, especially when it’s confined to small spaces. The chemical is produced by organisms that live in the sewer lines.

“When waste gets into the sewer and is carried along, various biological reactions occur and the dissolved oxygen in the water drops to nothing,” Elliot explained.

With no oxygen present, micro-organisms in the pipes survive through anaerobic metabolism of which hydrogen sulfide is a bi-product.

“It’s not an imminent public threat,” said the operations manager at the water treatment plant, Jerry Elliot, “it’s a bit of an annoyance and it does cost money.”

Elliot explained if the public is smelling it in their water at home, there’s a good chance the bacteria producing hydrogen sulfide is building up in the hot water heater.

“They like hot places,” Elliot said. “Those bacteria can get a stronghold and start to get going again [in the hot water heater].”

Elliot said the City has what they call a ‘sniffer’, which is a machine that they put into the water and wastewater systems before they physically enter. The sniffer will alert them to potentially hazardous levels of the gas. He also explained most people can detect the odor of hydrogen sulfide at 3 parts per million, which is way before levels become toxic.
While every city deals with hydrogen sulfide production within their systems, Ontario seems to have more than the typical city.

“This is not normal, it’s pretty excessive,” said city engineer, Betsy Roberts. “There are a lot of systems that don’t have the corrosion that we are seeing in our systems, the manholes, the concrete pipes.”

Elliot explained typically the most hydrogen sulfide is present in places where sewage is moving slowly, as is the case with pipes that are laid at a low grade, or at “stall-points” where it is stored before going through the City’s pump stations.

“It’s the nature of the sewer system,” Elliot said.

Ontario launched a project in December of last year to replace six concrete manholes on the dikes at the wastewater lagoons, which comes with an $11,600 price tag. The manholes, which had become dangerously corroded, are being replaced with new concrete manholes with a polyurethane lining that provide protection against corrosion.

The next repair project, which is the replacement of nearly 1,600 linear feet of existing sanitary sewer mainline and manholes, is scheduled to begin this coming spring . The city has contracted Anderson Perry & Associates, Inc., a civil engineering firm with offices in La Grande and Walla Walla, Washington, to design the project.

In addition to the sanitary sewer replacement project, Anderson Perry will be designing replacement or repairs for what CH2M Hill has dubbed ‘hot spots’ within the city.

“When [CH2M Hill] came in July were some hot spot areas requiring a lot of really intensive labor from the staff,” said Roberts. “We thought if we could get those tackled, and repaired or replaced, that would free up a lot of time.”

These ‘hot spots’ aren’t necessarily large areas. They are pieces of the city’s water and wastewater infrastructure that require constant attention from public works employees. Some of the issues include places that are easily plugged and “create potential overflow situations.”

With both pieces of the pending project lumped together, Roberts said the cost for completion would be around half a million dollars, but the ‘hot spots’ can be knocked off the list as budgeting allows.

“Having the design done so that some of our guys can come in and a do them later, would be fantastic,” Roberts explained. “I’d love to get the design done and we’re fine on budget for that.”

For the design piece of the project, the City is paying Anderson Perry $19,000, with an extra $2,000 set aside “only to be used if the city engineer requests their support in something.”

“I’m not sure why Anderson Perry did something and I can’t quite ferret it out than I can call them up and take a little bit of their time,” Roberts explained. “This is a standard practice.”

While they are taking steps to repair the damage inflicted by Hydrogen Sulfite, public works officials said they are also on the hunt for ways to lower the amount of it present in the system and prevent further damage.

“You can keep the water moving and we’re actually doing that with a project that Betsy is trying to kick out the door here in the next couple of months,” Elliot explained. “You can also change the cycle on your pumps, so it doesn’t hang around the pump bay longer than necessary.”


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