MGSD employees sickened by water; backflow guards installed
The Town of Minden and the Minden-Gardnerville Sanitation District are installing a backflow prevention system in the town’s water mains after fecal material contaminated water in a drinking fountain at the wastewater treatment plant and six MGSD employees became ill.
The contamination at MGSD occurred July 22-23. Officials believe the water become contaminated when a contractor working on a domestic service line to the wastewater treatment plan ruptured a line and inadequately repaired it. Employees who later drank from the water fountain at MGSD suffered severe bouts of diarrhea and vomiting.
“The contractor may have put the line back together and called it good,” said Rich Drew, Nevada public health engineer. “People using water inside the plant later on became violently ill from diarrhea and vomiting.”
Ray Wilson, Minden town board chairman, discussed the incident Wednesday at the town board meeting, citing his frustration at the town’s inability to order the water shut off to the wastewater treatment plant.
He said he was concerned that if there were low pressure, the bad water could flow back into the Minden pipes, contaminating the town’s supply with the E. coli bacteria that sickened the MGSD employees.
-Minden water OK. None of the contaminated water got into the Minden water supply.
Wilson said the state ordered the water supply left on to avoid burning out $360,000 worth of pumps in the treatment plant. Wilson said he was concerned that a thunderstorm or electrical outage could have lowered the pressure and caused the water to flow back into the Minden supply.
The contaminated water was isolated at the sanitation district and was treated with chlorination, said Minden public works director Greg Hill. Hill said samples of the contaminated water tested positive for E. coli bacteria and total coliform.
“As long as Minden maintained water pressure in the distribution system, there is no threat to the town,” Drew said. “If there were a fire nearby, or a line break, there could be a hazard. The town of Minden is correct to be concerned. This just kind of shows how the water system is pretty vulnerable.
“Everyone kind of assumes that water goes in one direction – out your tap. But if the water pressure drops because of a break in the line or firetrucks tying on a fire hydrant, those circumstances would pull water from the distribution system and cause water on the customer’s side to flow backwards into the distribution system.
“Water utilities don’t want that to happen,” Drew explained. “According to state law, once a water utility sells water to the customer and it goes through the meter on the customer’s property, the utility has lost control over the quality. Once they sell the water to you, they don’t want it back.”
Drew said the backflow prevention device keeps the water from going back into the system. The device required by the state depends on the degree of hazard caused by a potential backflow.
-High hazard. “Basically, any activity that involves sewage or a form of sewage is among the highest hazard,” Drew said.
“State law mandates a back flow prevention system, and Minden is way ahead of the rest of the state,” he said.
For sewage plants, the state requires an “air gap,” which Drew said is “a real simple, the cheapest and most effective” backflow prevention device.
“It involves separation of the water line on the utilities side which physically separates from water distribution on the customer side. It requires that the water actually falls through an open atmosphere into a tank. Then the customer has to repump it to supply pressure that’s needed inside the facility,” he explained.
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