Heavy rain causes sewer line overflow into French Broad

ASHEVILLE - Heavy rains in April caused a sewer line running through the Biltmore Estate to overflow into the French Broad River.

The public line, which overflowed at a manhole on the estate near 45 Fish Pond Road, expelled 25,130 gallons of rainwater and untreated sewage into the river starting at noon April 24. The overflow happened over 18 hours, according to a public announcement mandated by a state law due to the size of the spill.

Because of the heavy precipitation, most of the discharge was rainwater and didn't add measurably to the bacteria count in the French Broad, which was at flood stage following days of heavy rain, said Buncombe County Metropolitan Sewerage District officials.

"It would (have) very little impact to the river, because rainwater is what was in the sewer line to make it overflow," said Ken Stines, MSD system services maintenance director.

Stines said their gauges measured more than 4 inches of rain in two days.

Hartwell Carson, the French Broad "Riverkeeper" with the environmental nonprofit MountainTrue, said the assessment that most of the overflow was rainwater was likely true.

"I think that's a fair point, and one that often gets lost when people hear '25,000-gallon sewage overflow,'" Carson said.

But he added: "There's almost certainly sewage in there. And it's never a good thing."

Carson said MSD was one of the better sewage utilities that he knew of and was good at fixing problem pipes, often preventing overflows.

River bacteria counts do go up after heavy rain, but that is caused by disturbances of bacteria in sediment at the bottom of the river.

The 36-inch diameter line built in the 1960s by MSD runs along the east bank of the French Broad, paralleling the river and helping bring sewage to the treatment plant in Woodfin. One reason overflows can happen in that area is the older pipe is fed by a larger and newer 42-inch line upstream that also runs along the French Broad and brings sewage from the south, including from many unincorporated parts of the county.

The 36-inch line also receives sewage from an 18-inch line running from the east, bringing wastewater from South Asheville.

Rainwater can get in through old joints in the lines and manholes that haven't been updated with a special seal, said Stines.

In 2014, MSD used a $500,000 internal grouting technique that reduced some leaks but wasn't successful in sealing off enough of the line, the maintenance director said.

MSD workers are now in the process of lining the 21,000-foot pipe. They are in finishing the first year of the three-year process that should cost nearly $5 million.

The pipe is scheduled to be replaced by a larger line sometime over the next decade, Stines said. The replacement is estimated at $16.1 million. MSD is a public body funded by its sewerage customers throughout the county.