Report Backs New Mobil L.A. Pipeline : Environment: But major traffic problems are predicted during building of oil company’s Kern County-to-Torrance delivery system.

A proposed Mobil Oil underground pipeline that would traverse Los Angeles County from Santa Clarita to Torrance could cause large oil spills, but would pose far less risk than allowing the oil company to continue using the aged leaky line it would replace, according to an environmental analysis released this week.

The draft environmental report, compiled by a private consultant, acknowledges that the project’s 18-month construction phase will create unavoidable environmental disruptions, including noise and traffic tie-ups at major intersections in the Santa Clarita and San Fernando valleys, the Westside and the South Bay.

However, the report says that the larger capacity of the new pipeline would not result in an expansion of the company’s Torrance refinery, which has been the subject of environmental and health concerns because of air pollution emissions.

The proposed line would run 92 miles from Kern County’s oil fields to Mobil’s Torrance refinery, mostly following the route of a pipeline that has been plagued by six leaks in the last five years, including two breaks three weeks apart in 1988 in Encino and Sherman Oaks.

The pipeline began operating in 1916, but various sections have been replaced over the years. Segments of the pipeline now range from 2 to 55 years old.

Mobil decided to replace the pipeline after state fire safety officials voiced concern about corrosion in the line, which carries 63,500 barrels of heated crude oil a day at pressures up to 1,300 pounds per square inch.

In a possible setback to Mobil, the environmental report discloses that the U.S. Forest Service will not approve the project unless a 20-mile section is rerouted through the Angeles National Forest to avoid Pyramid Lake, a reservoir and recreational area. The Forest Service also wants Mobil to remove the portion of the existing pipeline that traverses the forest. The company had intended to rinse the pipeline with water and leave it in place.

Neither Forest Service nor Mobil officials could be reached for comment. But a spokesman for Dames & Moore, the consultants chosen by federal officials and the Los Angeles Department of Transportation to prepare the report, said rerouting the pipeline through the forest would increase the cost of the $88-million project by at least $1 million.

Mobil spent about $350,000 for the report after neighborhood groups and public officials last fall successfully urged Los Angeles to back off from an earlier recommendation to exempt the company’s plans from an environmental review.

The public has 60 days to comment on the study, and public hearings will be held in October before the final report is submitted to the Forest Service and the Los Angeles Board of Transportation Commissioners. According to the report, Mobil plans to begin construction next March if the project is approved.

Unlike the existing pipeline, which varies from 10 to 16 inches in diameter, the new line would be a standard 16 inches in diameter, enabling it to carry 91,000 barrels a day.

Despite the increased capacity, the report says, Mobil would continue to process about 120,000 barrels a day at its Torrance refinery--10,000 barrels below the level it is designed and authorized to process each day.

The report says that Mobil would not step up its operations once the new pipeline is operating but would cut down on the amount of oil it receives from other means. That includes oil from a 24-inch pipeline from its Southwestern Terminal in Los Angeles Harbor, the report said.

In an analysis of alternatives, the report argues that risk of oil spills would be greater if Mobil continues to use its existing pipeline than if it builds a new one.

According to the report, there is a 99.8% chance the existing pipeline will rupture in the next five years and cause a spill, compared to a 10.5% chance over a five-year period with the new pipeline.

The report acknowledges that the increased capacity of the new pipeline could mean larger spills, but recommends that several additional shut-off valves be installed to limit spills to no more than the amounts that would leak if the old pipeline ruptured.

The report concedes that, during the 18-month construction of the project, there would be bumper-to-bumper traffic or gridlock at some major intersections along the route for up to three weeks, along with noise and reduced access to cross streets.

To reduce the disruption, roadwork would not be performed during rush hours, and in some commercial zones all work would be done at night.

Mobil also is considering tunneling under some intersections to reduce the need for lane closures, according to the report, and would provide temporary parking lots and shuttle services in Santa Clarita, Hawthorne and Lawndale for residents whose access to their neighborhoods would be restricted during construction.

The pipeline would run beneath major streets like Woodley Avenue and Sepulveda Boulevard to its terminus at Prairie Avenue in the South Bay.