Fecal matter, sewage spills threaten water quality

by Sam Wilson
Wednesday, August 21, 2013

Staff photo by Allison Potter 

The N.C. Division of Marine Fisheries has lifted the swimming advisory that it placed on Banks Channel last week following heavy rainfall. 

After heavy rains produced runoff that forced the N.C. Division of Marine Fisheries to issue swimming advisories last week, Banks Channel is once again safe for swimming.

A division alert stated that four soundside advisories and one soundside alert were issued on Aug. 13 due to elevated levels of enterococci, a type of bacteria associated with the presence of fecal matter. Initial water quality testing showed enterococci levels up to five times the state and federal limits. By the following day bacteria levels had returned to normal.

J.D. Potts of the DMF’s Recreational Water Quality Program said in an Aug. 19 interview the heavy rainfall experienced in the 24 hours prior to testing likely contributed to the exceedance. The source of the bacteria, however, is more difficult to pinpoint.

“It could be a number of things,” he said. “It could be from human or animal; it could be from pet waste or birds.”

Listed as a Tier 1 site because of its high recreational usage, Banks Channel is tested weekly for elevated counts of the bacteria. While enterococci, which is found in the digestive tracts of warm-blooded animals, is not harmful to humans, water quality officials use the organism’s levels as an indicator of the overall sanitation level of the water, reported by the division’s recreational water quality website.

Potts explained that the water quality advisories for high usage areas are based on two separate standards.

“There are two criteria we use: the single sample and the running geometric mean, which is basically a monthly average,” he said. “For a single sample it’s 104. In Banks Channel we take triplicate samples, and if two of the three exceed 104 then it’s an automatic swimming advisory.”

Despite the precautions, however, Potts added that the division could potentially miss a period of elevated bacteria levels.

“If we have storm events in between sampling events, it could go unnoticed,” he said.

CFPUA addressing July sewer spill in Hewletts Creek

During their monthly meeting, the Cape Fear Public Utility Authority board members were briefed on the largest spill seen at the historically problematic Hewletts Creek pump station since November 2006.

On Monday, July 29, lightning caused the utility’s alert system to lose power at 29 of its pumping stations, including station 34, located near the intersection of Pine Grove and Greenville Loop roads. A nearby transformer then blew out, resulting in a power surge that shut off power to the station. A review by authority officials found that the surge tripped one of the breakers that would have been responsible for transferring power from a backup generator to the station.

CFPUA spokesman Mike McGill confirmed in a July 30 interview that heavy rainfall had played a part in diluting the estimated 441,881 gallons of sewage that leaked into Hewletts Creek. Water quality testing indicated that the elevated bacteria levels following the massive sewage spill had returned to normal by the next morning.

Jim Craig, the utility services superintendent who presented to the authority’s board on Aug. 14, explained the pump station power surge occurring immediately after the alert system outage was exceptionally unlikely. He added that a backup pumping system at the station had been reconfigured as a “third redundancy” — an extra safeguard should those events line up again.

However, Craig emphasized that the multilevel nature of the failure was a “freak of nature” and that there was no guarantee that a similar spill wouldn’t occur were those events to align again.

Included in Craig’s presentation were plans to hire an outside consultant to review the plant’s emergency operations and identify potential solutions to the system’s susceptibility.

email sam@luminanews.com

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