Independent Team to Probe Sewage Spill : Pollution: The state this week ordered San Diego to hire firm to determine cause of rupture.

The state’s Regional Water Quality Control Board has ordered the city of San Diego to hire an independent inspection team to investigate the cause of the massive sewage spill that occurred off Point Loma nearly two weeks ago, the city manager disclosed Friday.

The order came Tuesday, but City Manager Jack McGrory first mentioned the request at a news conference Friday in the midst of allegations that human error might have contributed to the spill, which is leaking 180 millions of gallons of partially treated sewage per day into the ocean.

“We do intend to hire an independent investigative firm to take a look at the whole situation,” McGrory said. “They will take a look at the whole situation, reconstruct it to the best of their ability, and have an independent analysis of what caused the break.”

The examination will include allegations raised Friday in The Times by five employees of the city’s Point Loma waste water treatment plant. The employees said an in-house operating error caused the plant and a huge outfall pipe to shake violently Jan. 31, two days before the break was discovered.

Specifically, one worker said a diversion gate and throttle valve were opened simultaneously in error, causing a large burst of air, called a “water hammer,” to surge through the plant and the pipe with tremendous strength.

A former official of the state water board told The Times that he had warned the city for years about the possibility of such an occurrence but that his pleadings were ignored.

During Friday’s news conference, McGrory and other city officials reiterated their position that nothing unusual happened except that workers diverted effluent from its normal path through a throttle valve because they needed to make a minor repair.

While the city could not categorically dismiss the possible presence of a “water hammer,” officials are holding firm to the theory that natural forces, such as the loosening of the ocean floor below the pipe, are to blame.

“At this point in time, you cannot rule out any of the causes that have been mentioned,” McGrory said. “We’ve heard discussions of boats, anchors, water hammers and waves as the cause. But our experts still believe the most likely theory is the theory of waves, excessive turbulence in the ocean and degree of waves hitting the outfall.”

Until the 22 sections of damaged pipes are pulled from the ocean in several weeks, he said, the city will not know for sure what caused the damage.

As part of its “cleanup and abatement” order issued Tuesday, the water quality board has ordered the city to hire an independent inspection consultant agreed upon by the state and the federal Environmental Protection Agency.

“Our argument is that they avoid any perception of conflict of interest of any kind,” said Michael McCann, assistant executive officer with the board, about the order to hire an independent consultant. “Someone new should step in and give it a fresh look.”

The investigation, whose results are due May 4, will include an examination of the damaged outfall, an inspection of the damaged pipe sections and a host of data obtained from the ocean.

If the city is found at fault, “the range of possibilities include being levied with penalties” or facing a connection ban, which would prohibit any new hookups to the sewage system that serves 1.7 million people, he said.

McCann said the city has been fined before because of discharges and shutdowns at Pump Station 64. But the Point Loma plant has never been cause for reprimand, he said.

McCann said his agency, which is controlled by the EPA, is a co-plaintiff with the EPA in its lawsuit against the city over the secondary-treatment issue. San Diego’s system of sewage treatment remains advanced primary, which removes less waste than the secondary method.

The EPA has issued a separate order requiring the city to develop a plan to further treat the sewage that is contaminating the ocean from the tip of Point Loma to Ocean Beach.

The city has had a La Jolla engineering firm under contract since 1989 to inspect sections of the 11,000-foot-long pipe. At various times, they have found evidence of corrosion at the top of the pipe, caused by the presence of air, but not enough to cause the break, company engineers said.

The spill was first detected by the U.S. Coast Guard on the night of Feb. 2, when it was first thought to be spewing no more than 2 million gallons a day from the break, which is 3,150 feet from the shores of Point Loma and in water 35 feet deep.

City officials soon conceded, however, that the pipe was losing its entire flow of effluent, as much as 180 million gallons a day.

Normally, the pipe, each section 25 feet long and weighing 30 tons, discharges the effluent--from which 75% to 80% of the solids have been removed--2.2 miles offshore at a depth of 220 feet.

The spill has created dangerously high counts of fecal coliform bacteria in areas ranging from the international border to the San Diego River in the neighborhood of Ocean Beach. Counts north of the river have been well below normal.

McGrory said Friday that the city had been notified by the Navy that, for the first time since the crisis began, high counts were recorded in San Diego Bay, although he attributed the readings to storm runoff, not the spill.

Bacterial counts worsened because flood waters forced the overflow of 12 million gallons of raw sewage a day from the Tijuana River. That spill has created more than 100 million gallons of contaminated runoff a day.

City officials said high counts were recorded Friday at the spill site itself, about a mile north of the Cabrillo National Monument. Readings there were 80 times the legal limit. Such counts have forced the indefinite closure of the Point Loma tide pools, which are routinely toured by schoolchildren.

The legal limit for bacterial counts is 1,000 coliform per 100 milliliters of water. Other high readings Friday were recorded at Imperial Beach (12,000), Silver Strand (10,000), Hotel del Coronado (5,800), Point Loma Navy property (28,000) and Ladera Street in Ocean Beach (4,000).