The U.S. Environmental Protection Agency (www.epa.gov) issued a final decisions to not renew the City and County of Honolulu’s variances exempting the Sand Island and Honouliuli Wastewater Treatment plants from full secondary treatment requirements. EPA has concluded that the discharges from the two plants do not meet the Clean Water Act’s conditions for renewed variances from requirements, which apply to most of the nation’s municipal sewage treatment plants. Specifically, the discharges from the two plants do not meet all applicable water quality standards. Neither of the plants’ discharges protect recreational use or marine life in the vicinity of the ocean outfalls, according to the EPA. As a result, the two plants do not qualify for renewed variances.
The city’s Sand Island plant, located in Honolulu, and the Honouliuli plant, located in Ewa, were both operating under variances from secondary treatment. With the final decision to not renew the variances, both plants will be required to upgrade to full secondary treatment.
In reaching these final decisions, the EPA considered nearly 600 comments received in writing and presented verbally at two public hearings. Written responses to all comments received have been posted on EPA’s website. In response to these comments, EPA made modifications to tentative Decision Documents released in 2007, but these changes did not alter the overall conclusions that the two plants do not qualify for renewed variances.
Primary treatment generally involves screening out large floating objects, such as rags and sticks, removing grit, such as cinders, sand and small stones, and allowing wastewater to settle, followed by the removal of collected solids. When secondary treatment is used, primary-treated wastewater flows into another facility where a large portion of the organic matter in the wastewater is removed by making use of the bacteria in the sewage. There are a variety of different biological treatment techniques that allow the bacteria to consume most of the waste’s organic matter.
The federal Clean Water Act generally requires municipal wastewater treatment plants to use both primary and secondary treatment. Amendments to the Act in 1977 allow for variances from secondary treatment for marine discharges, provided the plant meets water quality standards and other specific criteria as part of section 301(h) of the act. These variances are sometimes referred to as 301(h) waivers. Many coastal cities that once sought variances from secondary treatment, especially in areas where there is heavy recreational beach use, have chosen to upgrade their treatment plants to meet Clean Water Act requirements without variances.
For the written response to comments and the final decisions in this case, visit www.epa.gov/region09/water/npdes/pubnotices.html.