Raw sewage spill largest in 20 years
By Robbie Dingeman
Advertiser Staff Writer
By Robbie Dingeman
The 48 million gallons of raw sewage pumped into the Ala Wai Canal this week marked the largest release of untreated wastewater into Honolulu waters in at least two decades.
And yesterday's extremely wet weather caused additional sewage spills in Waimanalo, Kailua, Kane'ohe and central Honolulu, city spokesman Mark Matsunaga said.
Despite the heavy rains, city officials said repairs to the ruptured Kai'olu Street sewer line in Waikiki held and no more raw sewage was pumped into the canal.
It was that rupture — beginning March 24 and ending six days later — that has contaminated coastline waters in and near Waikiki and prompted city and state officials to post 103 warning signs urging people to stay out of the water.
State Department of Health spokesman Kurt Tsue said that if no more sewage is dumped and the weather improves, the water quality will improve within days.
The areas most affected by high bacterial levels are near Magic Island Lagoon and the Duke Kahanamoku and Fort DeRussy beaches. The latest water quality levels show a continued decrease in bacteria levels.
Mayor Mufi Hannemann has said he was forced to allow the raw sewage to go into the Ala Wai after the sewer line ruptured because the only other option would have been wastewater backup into Waikiki homes and hotels and other businesses, which would pose a much worse public health threat.
Hannemann said his administration made the repair of the 42-inch pressurized sewer main a priority, and crews worked around the clock to fix it.
City engineers are now designing a replacement pipe. Officials also plan to rehabilitate the existing line so it could be used, if necessary, should another line break occur.
This week's spill in Waikiki falls far short of the largest wastewater releases since the city began keeping such records in November 1982. But it's the largest recorded spill of untreated sewage.
The unofficial record shows that the 10 heaviest wastewater releases — with the Honolulu record of 471 million gallons set in 1986 — involved partially treated sewage that was pumped from treatment plants, said engineer Jack Pobuk, of the city Department of Environmental Services.
As for yesterday's sewage problems, the city reported more than a dozen spills around the island.
The city notified the state Department of Health about the spills. Warning signs were posted and water samples were being collected. The public is advised to avoid the affected waters.
"The weather service says O'ahu received an abnormal amount of rain in a very short period of time," said Ken Shimizu, deputy director of the city Department of Environmental Services. "That came at the end of the wettest March in 55 years, and it simply overtaxed our wastewater system."
Here is a summary of yesterday's sewage spills:
Power was restored and standby generators were turned out within minutes, but restarting the pumps takes time. The sewer system, already filled with rainwater that infiltrated the sewer pipes, was overloaded and sewage spilled from multiple points, in some cases dislodging manhole covers, the city said.
He said runoff from the heavy rainfall at midday — 2.67 inches in Waimanalo between noon and 1 p.m. — flooded the entrance to the plant and caused an unknown amount of raw sewage to escape from the plant inlet.
Reach Robbie Dingeman at email@example.com.