“The incident occurred around midnight on Tuesday, Sept. 14,” said Ferrysburg City Manager Craig Bessinger, chairman of the authority board. “Plant staff responded to the incident immediately upon their arrival and are looking at what needs to be done to prevent such an incident in the future.”
The incident caused about 830,000 gallons of sanitary sewage to be released from the treatment plant in Grand Haven, according to the authority. That led the county to issue a temporary health advisory for a portion of the Grand River until conditions improved.
“Plant Superintendent Dave Krohn is reviewing what would be necessary to prevent a repeat incident,” Bessinger said, noting that any fines as a result of the leak have yet to be determined or discussed.
The release occurred when the plant’s ultraviolet system, the last step of the treatment process, lost power, Krohn noted.
According to Krohn, there are two UV units to the treatment system — bank A and bank B. Each bank contains 72 UV bulbs that disinfect the effluent before it is discharged to the river. One bank is online and the other serves a backup.
“When we responded to the alarm, we found three fuses that were blown (and) replaced them, but the system would not start,” Krohn explained. “An electrician was called in and determined the main power supply unit on bank B failed. The reason it failed is unknown.”
Krohn said the failure may have been caused by a power surge or the power supply unit wore out.
The resulting loss of power on bank B caused another alarm preventing sewer plant employees from starting bank A.
“The manufacturer (Trojan UV in Canada) was called and directed us to a bypass switch on bank A, which allowed us to start bank A,” Krohn said. “The electrician obtained and installed a smaller power supply unit for bank B, which would work temporally, if needed, as a backup unit to bank A.”
A new power supply unit was shipped from Trojan UV and has been installed for bank B.
“We have had numerous phone conversations with Trojan the past week reviewing the settings and programming of the UV system,” Krohn added.
In February, a no-body contact advisory was also issued following a leak caused by a 2-inch hole in a main sewer pipe in the river. During that leak, officials estimated that slightly less than 2 million gallons of sewage was released.