A malfunction at the Lewes wastewater treatment that started Dec. 18 is expected to be repaired by the weekend.

Partially-treated wastewater is flowing into the Lewes-Rehoboth Canal after a failure at the Lewes wastewater treatment plant, prompting an emergency closure of local shellfish harvesting.

The Department of Natural Resources and Environmental Control was notified of equipment malfunctions at the Tidewater Inc. facility on Wednesday, Dec. 18, and the Surface Water Discharges Section observed conditions at the facility on Friday, Dec. 20. A public statement wasn’t released until late Monday, Dec. 23.

“Initially, it was believed that the repairs would take a relatively short time to complete. The severity of the situation was not understood by the facility operator until later, when the facility was unable to implement corrective measures,” said DNREC representative Michael Globetti.

Globetti said the facility held the effluent flow as long as possible, utilizing all available storage capacity, and only started discharging the partially-treated wastewater once capacity was succeeded. Since it is a municipal wastewater treatment plant that continuously accepts flow from multiple sources, including individual residences, the facility cannot simply stop accepting or diverting it.

According to a statement issued by DNREC, “Due to the nature of the affected equipment, the malfunction could not be expeditiously resolved, which required the Lewes [plant] to begin bypassing stages of its treatment, and began discharging partially-treated wastewater effluent from the facility the evening of Thursday, Dec. 19.”

The malfunction occurred when the wastewater treatment system's membranes, which are similar to filters, were contaminated during an automated backwashing process. According to multiple wastewater treatment system distributors, the backwashing process is typically used to clean the systems.

Until the system can be repaired, wastewater is being screened to remove visible solids and hydrogen peroxide is being utilized to reduce bacteria. Tidewater expects the new membranes to arrive at the plant by Dec. 27 for immediate installation.

The department is asking Lewes residents to reduce water usage, if possible. Water conservation measures such as avoiding multiple partial loads of laundry or dish washing, reducing shower time and minimizing unnecessary flushing of toilets are encouraged.

Residents are also advised to refrain from recreating in the Lewes-Rehoboth Canal, from one mile southeast of the Lewes plant north. Previous studies by DNREC found that the “net flow” of treated wastewater from Lewes enters the Delaware Bay, but not Delaware’s inland bays.