The Lewes wastewater treatment facility is back online and has resumed normal treatment of effluent, nine days after equipment failure forced the plant offline sending partially treated wastewater into the marsh near the Lewes-Rehoboth Canal.
Tidewater Utilities Inc. affiliate White Marsh Environmental Services, operator of the facility, informed the Department of Natural Resources and Environmental Control late Dec. 28 that contaminated filters caused the malfunction. Those filters have now been replaced. White Marsh had been bypassing the system and discharging disinfected effluent into the marsh adjacent to the wastewater facility. Lewes Board of Public Works President Pres Lee said the process removed some but not all nutrients and organics. The marsh acts as a natural filtration system, he said, removing most nutrients and organics before effluent reaches the Lewes-Rehoboth Canal.
During the bypass operation, DNREC staff directed sampling of partially treated effluent for bacteria levels and monitored the sampling for possible health risks. DNREC staff is currently gathering information to determine appropriate actions as a result of the incident.
The BPW, owner of the facility, was notified of a malfunction at the plant Dec. 19, which forced two of the plant’s four filter troughs out of service. The BPW was told the issue was minor and would be fixed within 12 hours. An accident involving an injury at the plant Dec. 21 alerted BPW officials to the fact that the problem had not yet been fixed, Lee said.
At some point between Dec. 21 and Dec. 23, he said, another part of the filtering process malfunctioned, allowing dirty water into the system. That problem took all four filter troughs out of service.
Lee said raw sewage did not enter the canal. Wastewater was diverted to holding tanks where it settled. It was then disinfected to meet required discharge standards.
New filters arrived from Canada Dec. 27 and were installed Dec. 28, allowing the plant to resume normal operations in one of four troughs, enough to provide service in the off-season, Lee said. White Marsh staff remains on site cleaning the filters for the other three troughs. Lee said a second trough should be up and running early this week. Work will continue to clean the remaining filters.
Residents are asked to continue water usage conservation, even though the fix has been made. Lee said water conservation is aimed at reducing the flow that has to be managed and discharged at the plant.
The BPW has also stopped receiving wastewater from Sussex County’s system. The BPW and county have an agreement that allows up to 300,000 gallons of wastewater to flow from the county to the BPW’s system.
When the system malfunctioned during an automated process and the bypass operation began, DNREC also ordered immediate closure of shellfish harvest areas in the lower Delaware Bay due to health concerns from partially treated effluent. The closure of shellfish harvest areas will continue for 21 days from the time the bypass situation ended and Lewes wastewater treatment plant’s effluent met required discharge standards. The closure ordered by DNREC is based on U.S. Food and Drug Administration guidelines under the National Shellfish Sanitation Program, and provides adequate public health protection for pathogens of concern, including viruses. The closure applies only to clams, oysters and mussels – crabs, conch and fish species are not affected.