Question: Can you help with a problem of water being discharged by the Board of Water Supply? Discharge occurs almost daily from the Waialua water tank. This has been occurring for years and at times is enough to fill a 16-inch pipe. I have been calling and writing the BWS for years and not been able to get any meaningful response. I was told for two years that they were not discharging any water. When they finally admitted that they are discharging water, I was told that they were flushing the filters and they have an easement to discharge water. This water is discharged directly onto the ground, where it erodes its way down to Helemano Stream, depositing mud into the stream. If it is necessary to discharge this much water, there should be a drainage system to control the erosion.
After a year of hauling and shoveling gravel, I have managed to reduce the amount of mud going into the stream, but it is an ongoing battle.
Answer: The BWS will investigate your concern about the water entering Helemano Stream and any possible erosion caused by the discharge of wash water from its facility at Waialua Wells, said spokeswoman Tracy Burgo.
We also contacted the state Department of Health about your concerns.
The DOH’s Clean Water Branch had issued a permit to the BWS allowing the discharge of water, said spokeswoman Janice Okubo.
The facility is authorized to discharge water once a month, so the Clean Water Branch “will investigate if the discharge is occurring more often and determine if there are permit violations,” Okubo said.
Meanwhile, Burgo explained that the water is coming from the BWS’ granular activated carbon (GAC) treatment facility at Waialua Wells, located on Kamehameha Highway about three miles before the Haleiwa/Waialua Weed Circle Interchange.
The treatment facility removes agricultural chemical contaminants from the well water, making it safe to drink, Burgo said.
She explained that the treatment facility consists of six large steel vessels called contactors, each containing 30,000 pounds of GAC and connected to a series of pipes. Of the six contactors, three operate at all times. Well water is pumped into the contactors to filter the water, which then is delivered to the BWS’ water system through the pipes.
“During this process, GAC is acting like a sponge to absorb contaminants from the water,” Burgo said. Periodically, the GAC has to be replaced because it can’t absorb any more contaminants.
It is this replacement process that generates the wash water. Burgo said the wash water also is treated and filtered to remove any contaminants and carbon particles before being discharged.
HOW MUCH WATER IS DISCHARGED?
Burgo said it’s difficult to determine how much water is being discharged.
“The water for this washing process is pumped from the well and not the on-site reservoir,” she said. “After the GAC is replaced, the new carbon will last up to a year before the process needs to be repeated again.”
The Waialua facility is one of 12 the BWS operates islandwide. The number of contactors at each facility ranges from four to 16, each undergoing periodic GAC replacement and generating wash water. Each is allowed to discharge that water under permits approved either by the state or the city Department of Environmental Services.
“These permits limit the discharge rate to 1,000 gallons per minute and require removal of any free alkali and other materials before discharging to drain,” Burgo said.
The carbon replacement/washing process takes place once a year for each contactor, lasting five to seven days each time. The permit allows a maximum water discharge of 1,000 gallons a minute, but this is not a continuous process, Burgo said.
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