WAIKIKI — A feverish effort to repair a broken main that has spewed more than 10 million gallons of raw sewage into Ala Wai Canal may pay off today.

Yesterday, crews patched the cracked 42-inch force main on Kai'olu Street by filling cracks with lead wool, wrapping the main with a resin fiberglass material and covering it with a reinforced concrete jacket, said city spokesman Bill Brennan. The three truckloads of concrete used as a cover will take 24 hours to cure.

"The feeling from those guys who work this stuff is that this will work," Brennan said. "At midday (today) we hope to turn the pump stations back on."

The state Department of Health is investigating if the break could have been prevented, said department spokesman Kurt Tsue. Fines are possible and the city may be asked to conduct a full environmental impact study, Tsue said.

Since the main broke Friday, raw sewage has traveled down the Ala Wai Canal, into the Ala Wai boat harbor and out to sea. Traces of it showed up at surf spots outside the harbor channel and some people feared kona winds might carry the waste to Waikiki Beach.

Waikiki lifeguards said they've had thousands of inquiries about the safety of the water since Friday.

Bryan Cheplic, spokesman for the lifeguards, said people were advised not to go into the water but lifeguards couldn't keep them out. "Thank goodness the weather is really bad so you don't have a lot of people on the beach," he said.

George Carayannis, who lives on a boat in the harbor, called the city's decision to dump untreated sewage into the canal unacceptable because of the health hazards.

"The tourists are not even aware," he said, adding that he's seen tourists, surfers and fishermen in the water since the break. The bacteria that is carried in sewage is not visible, Carayannis said. "The real danger is the material that cannot be seen."

DOH spokesman Tsue said sewage could drift to Waikiki and tests are being conducted daily between Diamond Head and Kewalo. A kona wind and high tide could also bring sewage back to Ala Moana Beach Park, which for the most part is safe, he said. However, warning signs to stay out of the water have been posted at Magic Island.

"Right now, the tides are taking it out," Tsue said. "Should the wind change, it could come right back into shore."

Tests show that the worst pollution is at the surf spots Ala Moana Bowls, Rock Pile and In Betweens, which are diamond-head of Magic Island.

Tsue said the city had no alternative to dumping sewage into the canal because the broken pipe is a force main, which is under constant heavy pressure.

The city tried to truck material away but once the main was shut, sewage would overflow into buildings, he said.

"In just a matter of minutes it could back up a whole hotel sewage system," he said. "The threat to the public and humans would be far worse than putting it into the canal."

Tim Ryan, who lives at the harbor, said the break is a travesty that could have been prevented with proper maintenance. The boating community is disgusted, he said.

"I hope the EPA comes in here and fines the city and county $1 million for every day this goes on," Ryan said. "Wait until people start getting sick in Waikiki. Wait until the wire service starts picking this up."

Boaters said the water smells but some areas are worse than others. The water was a dark green shade and was littered with what appeared to be cut pieces of dried grass yesterday. The green water was a good sign to Richard Olmsted, an architect who turned his boat into an office. For days the water was brown, Olmsted said.

"It doesn't look terribly polluted right now, but I wouldn't go swimming in there," he said.

Warning signs didn't keep surfer Joelle Tafoya out of the water. Saturday, the water was "gross" with material floating in the surf, so she didn't stay out long, said Tafoya, a University of Hawai'i student on spring break. She said she was used to poor water quality.

"I'm a lifeguard at Lake Michigan in Chicago so we have our share of bacteria in the water," she said.

The brown flow into the canal may stop today.

The breaks in the line on Kai'olu Street appear to have been caused by the heavy flow of rainwater into the sewage system and the settling problems of the old sewer line, officials said.

Repairs were difficult because rain kept filling the area around the pipe and because of the need to work around underground utilities.

The sewer line was built in 1964 to carry raw sewage from the Beachwalk Wastewater Pumping Station toward the Sand Island Wastewater Treatment Plant. The line carries most of the sewage generated in Waikiki, Manoa and Mo'ili'ili — about 15 million gallons each day, city officials said.

Reach Eloise Aguiar at eaguiar@honoluluadvertiser.com.