Press Release  MassDEP Penalizes Aquarion Water Company for Violating Drinking Water Regulations at its Oxford Public Water System

BOSTON — The Massachusetts Department of Environmental Protection (MassDEP) has assessed a $13,500 penalty to the Aquarion Water Company of Massachusetts for violating drinking water regulations during the operation of its community public water system in the Town of Oxford. Aquarion owns the Oxford public water system and operates and maintains four wells and three water treatment plants in town and distributes drinking water to 6,130 customers.

Potassium hydroxide is added to the drinking water at the Oxford water treatment plants to increase the water's pH for corrosion control purposes. The pH of undiluted potassium hydroxide ranges from 10 to 13; solutions with pH values at or above 11 can cause skin and eye irritations and possible exacerbation of skin disorders.

On June 21, 2021, the company notified MassDEP that a customer on Depot Road reported "slippery" water while showering, resulting in a skin rash. The company immediately investigated and found the pH at the customer's home and in other parts of the system to be 10, but as high as 11 at one location in the distribution system. The company immediately took corrective measures by issuing a reverse-911 call to affected customers and flushing the distribution lines to reduce the elevated pH in the drinking water. Normal pH levels of the drinking water in the Oxford system range from 7 to 7.5.

The elevated pH in the distribution system was determined to be caused by an overfeed of potassium hydroxide at the North Main Street water treatment plant. The overfeed was due to a malfunction of a valve that allowed approximately eight gallons of undiluted potassium hydroxide to flow into a pipe at the water treatment plant. The pH probe at the water treatment plant failed to detect the elevated pH from the chemical slug in the pipe, activate the alarm system and shut down pumps to prevent unsafe drinking water from being delivered to the customers. The valve and pH probe at the North Main Street treatment plant were subsequently replaced.

Under a consent order signed with MassDEP, the company must pay the penalty and hire a third-party company to conduct a comprehensive evaluation of all existing critical chemical feed systems at Aquarion's water treatment plants in Oxford and the Town of Millbury and provide a report identifying any corrective measures needed with a schedule for completion subject to MassDEP's review and approval. In addition, they must hire a third-party company to review and update Aquarion's Standard Operating Procedures (SOP) for its existing critical chemical feed systems to ensure its pH analyzers are properly managed and calibrated to measure a minimum pH of 10, and maintain a log documenting all testing of alarms and equipment maintenance. The revisions to the SOP and schedule for implementation are subject to MassDEP's review and approval. 

"Proper operations and maintenance of components to critical chemical feed systems such as a pH analyzer at water treatment facilities are essential to ensure the delivery of safe drinking water to its users," said Mary Jude Pigsley, director of MassDEP's Central Regional Office in Worcester. "It is important to test the components routinely and document those test results to ensure the safety system works as intended."

MassDEP's mission is to protect and enhance the Commonwealth's natural resources – air, water and land – to provide for the health, safety and welfare of all people, and a clean and safe environment for future generations. In carrying out this mission, MassDEP commits to address and advance environmental justice and equity for all people of the Commonwealth, provide meaningful, inclusive opportunities for people to participate in agency decisions that affect their lives and ensure a diverse workforce that reflects the communities served by the agency.

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