Heavy rainfall this week has resulted in significantly elevated bacterial levels in the treated sewage discharged from Kailua’s regional wastewater treatment facility, raising health concerns for beachgoers in the area.


Officials are currently investigating the factors contributing to this sewage issue, particularly as O?ahu braces for more heavy rainfall. The Kailua Wastewater Treatment Plant, situated on the island’s wettest side, has faced ongoing state and federal scrutiny due to previous occurrences of high bacterial contamination during storm events. The facility has been mandated to upgrade outdated equipment to enhance reliability and improve its ability to eliminate harmful bacteria effectively.


Despite these upgrades, City Environmental Services Deputy Director Michael O’Keefe emphasized that the plant remains susceptible to challenges related to sewage treatment during intense storms. This vulnerability persists even after the construction of a large gravity sewer tunnel connecting Kailua to K?ne?ohe, designed to manage the extensive rainwater that inundates the Windward side sewer system.


Storms can disrupt the sewage treatment process in various ways, including displacing the biological agents essential for purifying the sewage, according to O’Keefe. In some instances, it may not be immediately clear whether the rainfall impacted the plant’s operations or if other factors contributed to the issue. “These treatment plants are very complex, and many things could potentially go wrong,” O’Keefe remarked, as his team awaited confirmation of test results showing increased enterococci levels, which can be hazardous to human health, as noted by the National Institutes of Health.


As a precaution, warning signs were posted to advise swimmers against entering the water near the location where treated sewage is discharged into Kailua Bay. O’Keefe indicated that a thorough investigation would be conducted to ascertain the reasons for the abnormal bacterial levels exceeding state and federal safety standards, with results expected within approximately five days.


Earlier in 2023, the state Department of Health imposed a fine of over $400,000 on the City and County of Honolulu due to excessive bacteria in treated sewage over 13 days in late April and May. Some of those instances recorded bacterial levels six times higher than the permissible state limits, violating the city’s permit issued by the Hawai?i Department of Health. The city previously noted that these violations coincided with periods of substantial rainfall.


The U.S. Environmental Protection Agency has issued two consent decrees in recent years mandating the city to enhance operations at the Kailua facility and invest millions in necessary upgrades. Although work is ongoing, none of the projects have been completed thus far. Under an order issued by the EPA in September 2023, the city is required to refurbish one of the two bio-towers at the plant, which has suffered from corrosion and frequent breakdowns. These bio-towers are critical for exposing sewage to biological agents that eliminate bacteria through a trickling process that relies on a mechanical arm for proper distribution.


On at least one occasion, a malfunction of this arm led to spikes in bacteria levels. While it is currently functioning, state and federal authorities demand that the city upgrade this and other aging equipment in the tower. The estimated cost for the bio-tower rehabilitation project is around $42 million, with an expected completion deadline within four years, according to Environmental Services Department spokesman Markus Owens.


In a separate initiative, the city is reintroducing an ultraviolet light disinfection process at the Kailua plant to more effectively eradicate residual bacteria. This UV system had been in place until 2009, when excessive water flows damaged its components. The projected cost for this UV system is $11 million, despite a 2017 EPA estimate suggesting it should only be around $500,000. Officials have reassured that the new system will be safeguarded against flooding, aiming for completion by the year’s end.


Samples collected on Monday from inside the plant before the treated sewage discharge indicated concerning enterococci levels going beyond the state’s safety limits. The sewage is released about 5,000 feet offshore in Kailua Bay near the M?kapu Peninsula. Although the city’s press release did not provide specific details on how much the samples exceeded the permissible limits, it did report that the levels measured the previous day were considered safe and that ongoing testing would continue in the following days.


As O?ahu anticipates even more heavy rainfall starting Wednesday night, the Department of Environmental Services remains focused on investigating this incident, acknowledging that the plant has experienced significantly high flows due to recent rainstorms.