One Of Nantucket's Primary Water Pumps "Fried" After Reported Ground Fault

One of the Wannacomet Water Company's primary water well pumps was "fried" last month and must be replaced following an alleged ground fault.

Town Water Department director Mark Willett broke the news to the Nantucket Water Commission last Thursday, disclosing that the replacement pump will likely cost his department between $150,000 and $200,000 to install.

"This is not a cheap thing," Willett told the Commission.

With the pump at Well 14 now broken and another offline due to PFAS contamination, the Wannacomet Water Company has been supplying the municipal water system with just two pumps. But the situation did not escalate to a crisis, Willett said, due to the fact that it occurred during the offseason, and because he had been working with the island's irrigation companies to shut down private irrigation systems earlier than normal.

"The island experienced all kinds of ground faults and all kinds of electrical problems and well 14 was cooked - the pump in the well is junk," Willett told the Commission last week. "Luckily - so luckily for us - the irrigation guys started turning stuff off when they started."

Willet said a ground fault - when electricity takes an unplanned path to ground and the electrical current drastically increases - occurred on September 21st. National Grid representatives, however, said they found no indication of a power outage or voltage surge in the area servicing the ground pump that day.

During last Thursday's Water Commission meeting, Willett said the electrical issues and ground faults on that day even prompted the Nantucket Sewer Department to go onto its generator system, using more than 600 gallons of diesel fuel over the weekend.

"There was a ground fault," Willett said. "Something happened - either a massive surge or a massive drop in the power supply. Luckily, everything worked inside the motor control, and everything was protected. The drive is okay, which you would have added another $80 or $90 grand if the drive was gone, and that's not including the labor and the technician to come over and install. But something happened with the power supply, a surge or a drop, and it cooked everything down the well."

Though only eight years old and less than halfway through its expected lifespan, the pump would have cost more to repair than to simply replace, Willett said. A contractor sourced a new pump that has been delivered to the island and is scheduled to be installed on Wednesday, Oct. 22.

Two of Nantucket's public water wells at Wyer's Valley (Wells 15 and 16) pump groundwater from a shallow aquifer at about 75 feet, while the remaining three wells (Wells 12, 13, 14) pump groundwater from a deeper aquifer at about 150 feet beneath a semi-confining layer of soil that separates the two.

Wells 15 has been shut down since late 2022 due to PFAS contamination believed to be coming from an underground plume of the forever chemicals concentrated in the Toms Way area across Old South Road from the Wannacomet Water Company property. While Well 16 has not yet had a hit for PFAS, the Water Department has kept it shut off and used only as a backup because it has not been needed to meet demand, and out of concern about pulling the plume closer.

With Well 14 shut down due to the pump being compromised by the ground fault, the  Wannacomet Water Company has been able to sustain the Nantucket's demand and keep the island's water tanks at appropriate levels with just Wells 12 and 13 in operation.

Willett and the Nantucket Water Department are in the process of commissioning a new public water well at North Pasture, which would tap the deeper level of the aquifer. He anticipates it could be online within a year, depending upon the speed of the state Department of Environmental Protection's permitting process.