Honouliuli Wasterwater Plant plans its system upgrade, secondary treatment won’t come till 2024

HONOLULU—The Honouliuli Wastewater Treatment Plant is taking further steps to update its major conveyance system after years of pressure from groups that focus on Clean Water Act compliance.

Back in 2007, the Environmental Protection Agency (EPA) found that standards at Honouliuli allow for unacceptable levels of bacteria, chlordane, diedrin, whole effluent toxicity, chlorophyll, and ammonia in Hawaii’s waters. The EPA referred to a 2003 survey that found Oahu residents take part in recreational ocean activities beyond the two-mile mark from shore, within areas affected by the treatment plant’s dumping zone. The EPA also warned about the risks of consuming fish near the treated water’s outfall.

After years of legal stalling by the Mufi Hannemann administration—the former mayor once called the EPA’s findings “unfounded”—a legal settlement was reached between the City and County of Honolulu, the federal and State government, and three environmental groups in August, just weeks before Hannemann resigned in his unsuccessful bid for governor.

The City’s Department of Environmental Services is now looking to draft an environmental impact statement (EIS) for the public.

The centerpiece of the settlement is a comprehensive compliance schedule for the City to upgrade its wastewater collection system by June 2020.

Under the settlement, the Honouliuli plant must be upgraded to do secondary treatment by 2024, as Honolulu is the largest U.S. city that does not provide secondary sewage treatment before sending it into the ocean.

Since the end of 2009, the City had contracted engineering and architecture firm AECOM Pacific, Inc. to provide engineering planning for a study of the sanitary sewer system operated by the Honouliuli plant. With the end of the Environmental Assessment comment period, the City is now working to have its EIS and wastewater facilities plan by September 2011.

The Honouliuli/Waipahu/Pearl City Wasterwater Facililties Plan, which is an update to the West Mamala Bay Facilities Plan from 2001, will incorporate “emerging technology” for the construction of gravity sewer tunnel systems for conveyance and storage of wastewater flows.

There are different options for consideration in the planning process such as additional gravity sewers that will act as relief sewers, increased and additional pump station force mains, pump station capacity expansions and modifications, and peak flow storage tanks at pump stations.

According to AECOM, they plan on minimizing sanitary sewer overflows with new engineering concepts that will comply with the Department of Health and the EPA. The overall design also takes into account future needs for wastewater management, the firm said.

Along with the Honouliuli site, the Sand Island wastewater plant will need to be upgraded by 2035, but that could be extended to 2038 based on a showing of economic hardship.

City officials have said these upgrades could cost more than $1.2 billion.

For more information, visit www.honouliuliinfo.com.