48 Million Gallons of Sewage: A 'Drop in the Bucket' for Ala Wai Canal

posted in: November 2006 | 0

The sewage spill that sullied the already muddy waters of the Ala Wai canal from March 24 to 29 was not just large, it struck fear among locals and tourists alike. And the fears only heightened when Oliver Johnson, a Honolulu mortgage loan officer, died from a flesh-eating bacterial infection he contracted after falling into the Ala Wai harbor days after the spill.

“Unfortunately, Oliver Johnson passed away…That really broke the city’s back. Up until that point it was a business issue because we were pretty confident the public health aspect was being handled well by the Department of Health and our monitoring,” said Ross Tanimoto at a recent seminar at the University of Hawai`i at Manoa on the Ala Wai Spill. Tanimoto works for the City and County of Honolulu’s Environmental Services Department, which is charged with mitigating spills after they occur

According to the city’s water quality sampling, which tested for enterococci and clostridium bacteria, and its flow studies, bacteria levels never remained high for very long, and the water flowing out of the Ala Wai was flushed straight out to sea, and not along Waikiki beaches.

Despite the fact that the bacteria that killed Johnson, Vibrio vulnificus, is not a sewage-related pathogen, Tanimoto said, “When Oliver passed away, it really put a different turn on everything and it got the whole public afraid. There were cries that the mayor should go swimming and of course, he declined. So it became a huge PR thing.”

At the September 7 WRRC lecture, held in a UH Marine Science lecture hall, UH marine biologist Richard Brock stressed the need to put the Ala Wai spill – at least the bacteria levels involved – in context. Responding to a question by Brock about enterococci and clostridium bacteria levels near Date Street, which is mauka of the spill site, Tanimoto noted that the city found that levels there were high during the March event.

“Majority of the time, the station there had higher counts than the spill site,” Tanimoto said.

This, Brock said, brought up a good point.

“See, I’m not in favor of sewage spills. But it needs to be put into the proper context. And the comment I would make is, if you were to look at the entire watershed that drains to the Ala Wai, and look at when this happened relative to rainfall over the week previous to the spill, assume that you’ve got pretty saturated soil, … you’re going to probably find that that 48 million gallons is a drop in the bucket relative to what’s going through that system [drainage into the Ala Wai canal] at the time that this happened,” he said.

Tanimoto noted that the city’s Manoa Stream gauge indicated about half a billion gallons of water had passed through and that the Manoa discharge is about 30 percent of the overall tributary discharge into the Ala Wai canal.

“That’s why we estimate about a billion gallons discharged from March 24 to March 31. A lot of flow compared to our 48 milion [between March 24 and March 29].

Brock added that the flow in the Ala Wai came from a variety of sources.

“A lot of other sources. But, we can’t say that to the press. That’s not digestible,” Tanimoto said.

Tanimoto also said that of the 48 million gallons that the city pumped into the Ala Wai canal, the city estimates that roughly 20 million gallons of that was rain water.

“During rain events like this, 40 percent is due to I/I, infiltration and intrusion [of storm water]… 40 to 45 percent,” he said.

— Teresa Dawson

Volume 17, Number 5 November 2006

Leave a Reply