Repairs to Broken Outfall Line May Be Finished on Saturday : Sewage: Completion of work will mean an end to contamination of beaches near sewage treatment plant.

The city’s broken sewage outfall pipeline, which continues spewing up to 180 million gallons a day of partially treated waste, may be repaired by early Saturday despite the recent series of rainstorms, officials said Thursday.

Dave Schlesinger, director of the city’s Clean Water Program, said that unless a new storm arrives to delay repairs, 20 new 20-foot sections will have replaced the sections that came apart for reasons that are still being investigated.

The rupture of more than 500 feet of pipe was first detected Feb. 2.

Schlesinger said a special 44-foot-long “closure” piece will also be installed, as well as tons of ballast rock that boosted the cost of repairs from the $10 million originally predicted to $16 million.

City officials continue to maintain that heavy wave action during a storm is the most likely cause of the pipeline break that triggered one of the worst sewage spills in the nation’s history.

A Menlo Park firm, Failure Analysis Associates, which probed the explosion of the space shuttle Challenger and the collapse of the Hyatt Regency hotel walkway in Kansas City, is investigating the rupture. The firm’s report is due by mid-May.

Other possible causes for the break are human failure at the sewage-treatment plant creating a “water hammer” that filled the pipe with a massive air bubble, or a ship gouging and then breaking the pipe with its anchor. The outfall was installed in 1963 and had never ruptured before.

Officials had said as recently as last week that fixing the pipeline by April 4 would be difficult because of intermittent heavy rains since the rupture. But for the past several days, the 100-by-300-foot repair barge has remained at sea with crews working 24 hours a day for two weeks.

“Fortunately, when it rains on land, it isn’t always quite so bad at sea,” Schlesinger said. “What we worry about are ocean swells, but recently, sea conditions were such that we could work around them. We’ve had very successful days recently, and the operation has gone quite smoothly.”

The original cost for repairs was $10 million, then upped to $10.8 million and finally $16 million. Schlesinger said he and other officials decided to place almost $6 million worth of ballast rock as additional support for the nine-foot-diameter pipe.

Come Saturday morning, he said the outfall will resume its “normal” operation--discharging the effluent 2.2 miles offshore at a depth of 220 feet.

Since early February, the entire flow of the metropolitan region’s effluent--the system serves 1.7 million people--has been deposited 3,150 feet from the cliffs of Point Loma, at a depth of 35 feet.

The break, combined with heavy rains and an overflow of raw sewage from the Tijuana River, has kept bacterial counts from the international border to Ocean Beach at consistently high levels for weeks.

County health authorities said readings remain high from the tip of Point Loma to the E.W. Blom Wastewater Treatment Plant, to which the pipe is connected, to the Navy property several miles north. Weeks of health advisories have warned against swimming or eating fish harvested in the area.

The pipeline was again a subject of discussion by the San Diego City Council, which spent four days promising to review the sewage situation but not getting around to it until late Thursday afternoon.

The council discussed City Manager Jack McGrory’s recommendations for raising sewer rates to pay for repairs and improving the sewer system, but put off any action until April 21. The council did resolve to seek state and federal funding to pay for $2.5 billion in construction to meet federal clean water guidelines.

“We’re in a recession right now and dipping dangerously close to a depression,” Mayor Maureen O’Connor said, adding that state and federal support was virtually the only way the city could hope to comply with the guidelines.

O’Connor said the council couldn’t act Thursday on McGrory’s rate proposal, because “you’d have nine different opinions.”

Councilman Tom Behr introduced his own proposal, which largely rejected McGrory’s plan to double sewer rates by the year 2003, and which depends on seeking a waiver in federal court to keep the city’s level of treatment at its Point Loma facility at advanced primary.

A law suit pending in federal court requires the city to upgrade to secondary treatment at Point Loma. The suit is based on the federal Clean Water Act, which mandates that every city in the country adopt secondary treatment of sewage.

Behr argued that the city’s advanced primary method--which removes 75% to 80% of the suspended solids in the effluent, rather than the 90% that secondary treatment removes--represents “no significant harm” to the marine environment. He said maintaining advanced primary could save area ratepayers “in excess of $1 billion.”

Verna Quinn, who represents the Sierra Club--which is a party in the suit along with the U.S. Environmental Protection Agency--spoke against Behr’s plan and for McGrory’s, saying reclaimed water and secondary treatment were environmental necessities mandated by law.

“We think reclamation is a high, high priority,” Quinn said.

The city manager’s plan calls for 15% sewer rate increases beginning July 1 and taking place each year through fiscal year 1997, followed by an 8% increase in 1998 and 1.5% increases each year through fiscal year 2003.

Such increases would elevate sewer rates from $22.13 a month in fiscal year 1993 to $45.06 a month by 2003. McGrory proposed a series of alternatives that would lower the increases but which depend on lucrative state and federal support and assistance from other cities in the county.