Chantal Wreaks Havoc on Sewer Lines

The Bolin Creek wastewater spill occurred between MLK and Bolinwood Drive along the Bolin Creek Greenway.

Tropical Storm Chantal hit Chapel Hill on Sunday night, June 6, with record rainfall. The OWASA sewer system was one of the storm’s victims along with numerous neighborhoods and businesses throughout both Chapel Hill and Carrboro. For OWASA, the impact was threefold.*

There was an overflow at the wastewater treatment plant resulting in 2.7 million gallons of incompletely treated wastewater entering Morgan Creek. On Monday morning a sewer line overflow was reported in the Kings Mill neighborhood where 819,000 gallons of untreated sewage entered Morgan Creek before it reached the wastewater treatment plant.

The third sewer overflow occurred on Bolin Creek along Bolinwood Drive on the Bolin Creek Greenway. This was the smallest overflow, just 157,500 gallons of sewage, but it is the most visible due to its presence on the popular Bolin Creek Greenway.

Two miles of paved greenway lies between Umstead Park and the Community Center, all of which runs parallel to Bolin Creek and one of OWASA’s sewer lines. Whenever Bolin Creek floods, which is not infrequently, the greenway floods. But this time, the water moved faster and rose higher than past floods.

The manholes, the areas where maintenance staff can open the sewer line for inspections and repairs, were overtopped and many of the covers were swept away with the flood waters. Stormwater overtopping the manholes isn’t unusual for those manholes that are flush with the ground. But along this section of the greenway, the manholes are elevated by about 4 feet. Under normal times, they provide space for public art along with their functional purpose. But under Chantal, even they were overtopped. Many are laying on their sides away from their original locations.

Raised manhole covers were swept off their base by the force of the floodwaters along stormwater, rocks and other materials to enter the sewer lines.

That damage allowed stormwater to enter the sewer system and oddly enough, rocks, rocks of all sizes, fell in and must be cleared out before the sewer line can be repaired.

That’s what is happening at the bridge over MLK Blvd today. OWASA’s subcontractor, Moffat Pipe (a woman-owned construction company!), is cleaning out the rocks so that the temporary sewer line (the black pipe in this photo) can be removed, the permanent line re-engaged, and the greenway re-stablized and cleaned up.

Temporary sewer lines runs atop the greenway until the rocks and other debris can be cleaned out of the permanent lines.

*Reported sizes of the wastewater spills were taken from a Chapelboro report.