Aging Pipes Made Sewage Spill Worse

Deteriorating sewer pipes, a large blockage and a shortage of repair parts caused leaks that spilled about 800,000 gallons of raw effluent into Arroyo Conejo Creek in Thousand Oaks over the weekend, city officials said Monday.

A 12-mile stretch of the creek from Thousand Oaks to its terminus at Point Mugu has been posted as unsafe for swimming by Ventura County health officials. The ban is expected to last about five days until the bacterial concentration is diluted by creek waters, said Elizabeth Huff, a county environmental health specialist.

City officials said the spill, which occurred in municipally owned open space, did not pose a public health risk. The nearest housing is about a quarter of a mile away.

About four dozen fish have died so far as a result of the spill. Damage to wildlife is not expected to be significant because the discharge occurred downstream of deep pools where green perch, arroyo chubs and catfish breed, said Greg Smith, the city’s environmental planner.

Leak Started Saturday

The sewage--in volume the equivalent of about 160,000 toilet flushes--began leaking Saturday afternoon from the first of two breaks in an aging eight-inch steel pipeline in the northwest corner of the city, said Kurt O. Reithmayr, principal engineer with the city Utilities Department.

Problems began when an obstruction in a 30-inch pipe nearby built up pressure and cracked the smaller line, Reithmayr said. The cracked pipeline is 25 years old and was scheduled for replacement this year, he said.

The leak was spotted Saturday afternoon by a security guard patrolling the adjacent MGM Ranch property, Reithmayr said.

To reduce the pressure, city crews opened the smaller line Saturday but couldn’t recap it because they did not have a large enough plug and could not get one from nearby agencies, Reithmayr said. As a result, thousands of gallons of additional sewage leaked from the line before it was sealed Sunday, he said.

“It’s like you have a hose and you’re trying to make the darn thing stop gushing, but you can’t,” Reithmayr said.

2nd Leak

A second leak sprang open in the line Sunday a short distance from the first. Both breaks were clamped and sewage stopped leaking into the creek Sunday. City crews also opened a bypass pipeline to reduce the pressure, Reithmayr said.

Workers were still working Monday evening to remove the blockage in the larger line, which Reithmayr said could be rocks, wood or even a bicycle.

The larger line flows west through Wildwood Canyon to Hill Canyon Wastewater Treatment Plant north of Newbury Park. The smaller line flows north from the Ventura Freeway through Arroyo Conejo Canyon to the plant.

The state Regional Water Quality Control Board will investigate the spill and could levy fines if it finds the city was negligent, said David Gildersleebe, a supervising engineer for the agency.

The city discharges about 10.5 million gallons of treated waste water daily into Arroyo Conejo Creek. In 1978 and in 1981, flooding from winter storms resulted in minor spills of untreated sewage into the creek, city official said.