NEW HANOVER COUNTY — A 40-hour sewer spill caused by a ruptured, aging force main added an estimated 2.44 million gallons of untreated wastewater to local waterways this week.
The spill is the second largest in Cape Fear Public Utility Authority’s history, ranking only behind a September 2018 Hurricane Florence-related incident that dumped 5.25 million gallons of wastewater into the Cape Fear River.
In all, the spill lasted at least 40 hours after being discovered at 8:30 a.m. Tuesday and stopped with a temporary pipe at 12:55 a.m. on Thursday morning. The spill temporarily shut down one half-mile of traffic on One Tree Hill Way for two days.
Water quality test results provided by the Cape Fear Public Utility Authority (CFPUA) show levels of fecal coliform in nearby waterways spiked drastically after the spill was noticed.
The highest measurement of the bacteria, 648,800 organisms per 100 milliliters of water, was recorded midmorning Wednesday at the entry point of the spill in Smith Creek. This result was 37 times higher than a measurement taken at the same location Thursday afternoon after the spill stopped.
Test results show fecal coliform levels on the rise as of Thursday afternoon (the most recent results available) at two sites tested nearby at Burnt Mill Creek and near the 23rd Street Bridge.
View an interactive map of locations sampled with a basic breakdown of when measurements of fecal coliform peaked below. Note: Four locations were sampled at three different times. Data provided courtesy CFPUA.
Environmental Management staff members at the utility are continuing to monitor water quality in the area, according to a CFPUA release Friday afternoon.
Bypass now in place
Since first noticing the spill 8:30 a.m. Tuesday, Cape Fear Public Utility Authority (CFPUA) crews worked nonstop to curtail the wastewater overflow near Pump Station 10 on One Tree Hill Way.
Three vacuum trucks diverted 500,000 gallons of wastewater from the site before crews installed a temporary 500-foot bypass, stopping the spill just before 1 a.m. Thursday.
The rupture occurred spontaneously, caused by an aging ductile iron pipe that was already scheduled to be decommissioned in June 2020. Work on replacing Pump Station 10 was underway at the site, which is how construction crews first noticed the incident. This summer, the replaced Pump Station 10 is expected to open and the existing station, built in 1967, is set to be demolished.
CFPUA’s temporary bypass connects to a 30-inch force main that was recently constructed as part of the Pump Station 10 replacement project.
This week’s wastewater spill is the utility’s largest non-storm related overflow event, according to figures provided by CFPUA.
During Hurricane Florence, the utility released 5.25 million gallons of partially-treated wastewater at its Southside Wastewater Treatment Plant after two generator failures.
Hurricane-force winds prolonged the utility’s ability to intervene, with the spill lasting a total of nine hours and 20 minutes. “Partially” treated wastewater means some portion of the wastewater had already been treated in a condition to be released while some remained untreated.
Following this week’s event, the utility’s third-largest spill occurred in January 2012 at Barnards Creek at River Road, with 1.4 million gallons released; at 441,841 gallons, CFPUA’s fourth-largest spill occurred July 2013 at Pump Station 34 at Pine Grove Drive; in August 2012 CFPUA logged its fifth-largest spill, releasing 386,000 gallons near South College Road and Kerr Avenue.
For context, CFPUA spokesperson Vaughn Hagerty pointed out the utility had only spilled a total of 3,550 gallons with 1,200 gallons that reached surface waters among three spills in all of 2019. Last year, the utility responded to 35 spills, with nearly half being hurricane-related.
An estimated 72,000 gallons of wastewater spilled from the same location as this week’s event — Pump Station 10 at Smith Creek — due to a suspected power outage in June 2018, according to CFPUA’s 2018-2019 Wastewater System Performance Report.
Hagerty referenced a professional benchmark that measures spill events, stating this year’s performance metrics prior to the spill this week were well ahead of industry standards.
“The American Water Works Association sets an industry-wide benchmark for utilities of 2.7 [sanitary system overflow] events per 100 miles of sewer line in a 12-month period. CFPUA’s SSO target rate is 1.62, 40 percent lower than the AWWA benchmark,” Hagerty wrote in an email.
“At the start of December, the SSO rate for the CFPUA system was 0.32 events per 100 miles of sewer line for the previous 12 months.”
Send tips and comments to Johanna Ferebee Still at email@example.com