A year after the city pumped 48 million gallons of raw sewage into the Ala Wai Canal when a major sewer line ruptured in Waikiki, officials are scrambling to prevent similar disasters in the future.

Hundreds of millions of dollars are in the pipeline for repairs across O'ahu, and residents are facing the steepest sewer fee increases in decades to pay for the work.

Meanwhile, environmental groups that have repeatedly sued the city over its sewage problems are asking a federal court to require the city to do more.

And the Environmental Protection Agency may soon levy a hefty fine for the Waikiki spill — the worst sewage mess in state history.

The city diverted sewage into the Ala Wai for six days after the 42-inch pipe ruptured, prompting health warnings that closed world-famous beaches in Waikiki, the state's premier tourist destination.

Crews finished installing a temporary bypass line along the Ala Wai late last year, which can carry any overflow sewage to a treatment plant. A permanent line is scheduled to be completed this fall. The expected cost for the two lines combined is $50 million.

The city also is replacing the pressurized pipe that ruptured, known as the "Beach Walk Force Main."

Meanwhile, $350 million worth of additional sewer work is planned for the coming year, including a $66 million expansion of the city's main sewage-treatment plant on Sand Island.

The city already has completed about $350 million in expansion work at the plant over the past decade.

PREVENTION PRIORITY

The EPA said that although it likely will fine the city for last year's spill, the agency's main priority is to prevent future problems.

"We want to ensure that all necessary steps are taken to repair and maintain Honolulu's sewers so there's not a repeat of the Beach Walk spill," said EPA spokesman Dean Higuchi. "That spill illustrated the consequences of not maintaining Honolulu's sewer infrastructure."

Mayor Mufi Hannemann has proposed a series of sewer fee increases that could raise the average monthly charge to more than $90 by 2011. The current average charge is less than $45. The increases are awaiting a series of City Council votes, and key members have indicated that approval is likely.

"The mayor has placed a high priority on sewer repair and replacement generally and Beach Walk in particular," said administration spokesman Bill Brennan.

The fee hikes "are some of the steps that need to be implemented by the city," said the EPA's Higuchi. "Over the long term, we believe it's necessary for the city to demonstrate its implementation of sewer system improvements. We understand it's going to be a challenge for the city for the next 10 to 20 years because there's a lot of work that needs to be done."

FEDERAL SUIT FILED

Three environmental groups that sued the city in 2004 after a series of earlier sewage spills are now asking a federal court to order that the city assess its sewer system, prioritize projects based on the risks they pose and create a comprehensive plan to manage sewer breaks.

The Sierra Club, Hawai'i's Thousand Friends and Our Children's Earth Foundation charged that the city has violated federal wastewater standards for years by failing to fix and maintain sewer lines and facilities in a timely manner.

The groups are asking the court to reconsider an earlier ruling that rejected their request for an immediate judgment on parts of the suit.

Negotiations with the city to settle the suit have reached an impasse, partly because of disagreements over how many times the city violated the federal Clean Water Act, court records show. The plaintiffs contend there have been more than 14,000 violations.

The city argued in court papers that the ruling should not be reconsidered because the groups have not presented new arguments.

Since 1995, the city has been under a federal consent decree that requires comprehensive sewage system improvements as a result of an earlier suit.

Two years before the Waikiki spill, a report commissioned by the city warned that the pipe was among seven considered to be in "very critical" condition, and recommended that a backup line be installed. The same pipe had suffered smaller ruptures in 1993 and 2004.

The city prepared a plan for the work and set aside $30 million, but repairs were not made before the pipe ruptured last year and forced the closure of several South Shore beaches to swimmers, surfers and canoe paddlers.

Reach Johnny Brannon at jbrannon@honoluluadvertiser.com.