The city has started work on an emergency bypass sewage line that would travel through a tunnel under the Ala Wai Canal, then into a pipe lying on the bottom of the canal.

Mayor Mufi Hannemann said he is pushing to build the bypass as quickly as possible — targeting completion for the end of this calendar year — to prevent another spill like the record one that began March 24. "We want to make sure it never happens again," he said.

When the 42-inch sewer main ruptured in Waikiki, the city pumped 48 million gallons of raw sewage into the Ala Wai Canal rather than allow it to back up into nearby homes and businesses. The spill fouled some of the state's most famous beaches, kept swimmers and paddlers out of the water and made national news.

Preparations for the bypass are under way, with large sections of pipe delivered along the Ala Wai and orange paint pointing out the path of construction while the city awaits state help before the project gets into full swing.

The first phase of construction will run a temporary sewer line from the mauka bank of the Ala Wai Canal to join it to another sewer line near the diamondhead entrance to Ala Moana Park. That section of pipe will run along the canal bottom, said City Environmental Services Director Eric Takamura.

He said people in Waikiki will see seven pumps lined up along the Ala Wai to divert sewage flows from the existing pump station to the new bypass pipe during construction of the bypass. While that will resemble the pumps that sent raw sewage into the canal, they will be working to keep sewage out of the canal, Takamura said.

Then the second phase will begin, using a microtunneling process to carve out a tunnel that will run for about 1,000 feet under the canal from the Beach Walk pumping station, along Kai'olu Street — site of the break — to the mauka side of the canal.

The $20 million bypass line will be used as a backup in the event of another major sewer line break in Waikiki. It can also be used during the construction of the permanent fix — a new sewer line that will cost an estimated $30 million. The temporary pipe will remain in place for at least five years until the old line is rehabilitated to serve as the backup.

Once the work begins, some disruptions are inevitable.

Traffic will be affected intermittently on Kai'olu Street and at the entrance to Ala Moana Park.

Near the neighborhood park along the mauka side of the canal, crews already tore out a park bench. A nearby bike path is being detoured, and a portion of a softball field will be closed for a construction staging area.

Leslie Nakagawa, who tends one of the community garden plots near where the construction will occur, said she hadn't heard specifically that the construction would uproot some of the existing plots.

Nakagawa grows tomatoes, bok choy, basil and even grapes alongside the Ala Wai. She pointed to a notice on the garden bulletin board that warned only of the project's "impact" without saying five plots will be moved.

"That's going to make the people on that side upset," she said.

Hannemann thanked Waikiki residents and visitors in advance for coping with the construction through the busy resort community.

City officials have hired a consultant to run a project hot line, establish a Web site and do community outreach during the project.

Waikiki Neighborhood Board member Mike Peters said he thinks most people in the community believe the project is needed. "It has to be done," he said.

Peters, a hotel employee and substitute teacher, said the community will accept months and years of sewer construction as long as it doesn't become delayed and troubled, when "the mood may change."

The city is still awaiting word from the Environmental Protection Agency on what actions federal officials may take against the city over the record-breaking dumping of raw sewage.

Rick Egged of the Waikiki Improvement Association said news of the spill "had a negative impact," but visitors seem to be surging back without a lingering setback.

Egged sees more community awareness of the need for this sewer project, even among those who helped stop similar plans in years past. "I don't think you'll hear much opposition," he said.

Hannemann said yesterday that he asked Gov. Linda Lingle to clear the way for expedited state approvals for some key permits. "This is an utmost priority of my administration," the mayor said.

He said Lingle responded to the request with pertinent follow-up questions that the city is answering in seeking approvals from three state departments to start the work soon.

Sierra Club Hawai'i Chapter executive director Jeff Mikulina supports the city's recent efforts to move quickly on starting both the temporary and permanent fixes. The environmental group was among several citizen groups that sued the city to improve the sewer system.

"We offered the city to send a letter to the governor in support of their request to waive environmental impact requirements," Mikulina said. "The environmental impact of doing nothing could be much worse than what they're planning."

Mikulina said the Sierra Club also offered to help work with community groups to assuage concerns. And he said the city is working on fixing the problem and upgrading the sewage system.

He did note that the City Council this week approved the latest payments to a Mainland law firm hired by the city to fight the Sierra Club's earlier lawsuit citing environmental concerns, bringing total legal payments to the private firm to $2.5 million.

"It's surprising that they would have such a high-priced defense against the citizens' groups," he said.

Reach Robbie Dingeman at rdingeman@honoluluadvertiser.com.