In the past two years, there have been 136 sanitary sewer overflows in Eastern North Carolina.

HAVELOCK -- When the forecast calls for heavy rain, Jim Wynn walks around his Oakwood Drive house and pulls the chains up on commodes so nobody accidentally flushes them.

The action is necessary because Wynn installed a valve that shuts his house off from sewage service during heavy rain in an effort to keep dirty water from backing up into his house every time Mother Nature drops an inch or so of rain on Havelock.

"We've actually got to where we assume that when it's raining we can't use the water," Wynn said. "It does wonders for the resale of the house, too."

Between Jan. 1, 2016, and Dec. 31, 2017, Havelock reported at least eight spills from an Oakwood Drive manhole in front of Wynn's home. Those sanitary sewer overflows are among the 136 reported across swaths of coastal North Carolina during that period, according to N.C. Department of Environmental Quality records, events that researchers and environmentalists say could bring humans into contact with risky waters.

Cape Fear Public Utility Authority, in Wilmington, had the most spills in the region with 27, according to DEQ records. Brunswick County Collection System had the second-most, with 22 spills in 2016 and 2017.

"Lots of sewers are gravity fed, so many of them follow streams and creeks, so they're in flood-prone areas, and when you have heavy rain events, they become inundated with storm water," said Matthew Starr, Sound Rivers' Upper Neuse riverkeeper.

Impacts of spills

When the manhole in front of Wynn's home overflows, the untreated wastewater flows into a small creek by his home that leads to Caps Branch and then into Slocum Creek.

"In the wintertime, it's annoying; it's nasty," Wynn said. "In the summertime, it stinks. It flows over into the creek and the creek runs alongside the side of the property; it smells bad and it goes downstream."

Odor is not the only problem caused by overflows. Rachel Noble, a UNC Institute of Marine Sciences professor, has researched how spills impact water quality, particularly in the Hampton Roads area after Superstorm Sandy.

When a spill occurs, the measure for whether the water is safe to come into contact with again will typically involve E. coli or other fecal indicator bacteria.

"We use the bacteria as a proxy," Noble said, "but the bacteria don't tell us the whole story we want to know because the viruses that come into that water body persist a lot longer than the bacteria do."

Generally, Noble said, bacteria can linger in water for days to a low number of weeks, while viruses can last for weeks, depending on the strand. After Sandy, for instance, Noble was still seeing a signal for viruses 45 days after the event.

"They're going to persist longer in the cold winter months than they would in the summer months," Noble said. "In the summer, it's warmer, there's more sun to degrade them, there's more sun around to eat them."

In murky rivers like the Cape Fear, Noble said, viruses can attach to particles or algae that are then filtered through shellfish, where they can become lodged and later eaten.

Preventing spills

Both utilities and their customers bear responsibility for preventing spills, Starr said. While utilities need to keep pipes and other infrastructure updated, Starr said, customers should avoid flushing wipes or pouring grease down the drain.

Infrastructure failures such as pipe or pump station failure resulted in 39 spills over the two-year period, while grease caused 16 and other debris in lines led to 14 additional spills.

The largest spill in the region was caused by Hurricane Matthew's rains, with Kinston reporting a 44.9 million-gallon spill on Oct. 8, 2016. In total, the other 137 spills in the region during 2016 and 2017 discharged 1.16 million gallons.

Joel Ducoste, an engineering professor at N.C. State University, uses computational fluid dynamics to model water and wastewater treatment processes. Typically, he said, utilities struggle with keeping excess oils, fats and greases out of pipes, often from restaurants.

When the oils do enter the sewer system, Ducoste said, they break into fatty acids and glycerol, merging with calcium that is either in wastewater or leaching out of the infrastructure to create a soap-like substance that can build up over time.

These build ups need to be periodically cleaned up by utilities, Ducoste said, but also addressed by educating restaurants to be careful about dumping the substances into wastewater systems and using grease interceptors to catch what does end up there.

"There's miles and miles of sewer pipe that between small cities and large cities they have to go through and try to provide maintenance and identify where these blockages might form," Ducoste said.

Situations such as the one in Havelock, where there are repeated spills in the same place, are familiar to many utilities, Ducoste said. Kinston Collection System, for instance, reported three spills at Springhill and South Herritage streets between April and May of 2017.

Ducoste said, "They probably can tell you where their hot spots are, their locations where there is a higher accumulation. ... Sometimes it happens deep enough within the collection system that it's hard to determine where the source is."

In a statement Friday, Mark Sayger, Havelock's public services director, said the city has assessed much of its collection system using a cleaning and video inspection procedure. The city also replaced a manhole near Oakwood Drive that had settled and was leaking, he said.

"Sewer lines near the Waste Water Treatment Plant were also evaluated and cleaned," Sayger wrote. "The City of Havelock is continuing these actions to mitigate inflow and infiltration issues in the collection system."

Sayger also said Havelock is replacing a leaking line that it believes may represent a "significant" source of inflow.

Reporter Adam Wagner can be reached at 910-343-2389 or Adam.Wagner@GateHouseMedia.com.