Sewer project in the pipeline

South Coast Water District will be digging up some pricey dirt if proposed repairs to a tunnel and replacement of a sewer pipeline are approved.

The 55-year-old tunnel runs for about two miles from South La Senda Drive in Three Arch Bay north to Aliso Beach. The project and its effect on the environment are outlined in a recirculated draft environmental impact report available to residents for review at the district office and on its website. Written comments may be submitted through 6 p.m. Oct. 11. Oral and written comments were also solicited at a Sept. 9 public hearing.

“At one point they were going to gain access to the tunnel through [Three Arch] properties and the community was quite upset, but they are not going to do that,” said former Mayor Kathleen Blackburn, a long-time homeowner in the gated community. “It is a big project and it was going to be disruptive to a good number of rate payers and that was a big consideration.”

Project plans call for the enlargement and stabilization of the tunnel in a horseshoe shape so pipeline failures can be averted and the access made safer for district personnel who maintain and inspect the facility.

The tunnel measures about 6 feet wide and 6 feet high. It burrows through sections of the San Onofre Formation brecia, sandstone and siltstone. Most of it is located within beach cliffs, and it runs generally parallel to the cliff.

Loose rock and rotten timber supports that could harm workers or the sewer line will be removed and a new pipeline installed with the older line remaining in place. The existing grades will be maintained so lift stations will not be needed and there will be no operational changes in terms of function or capacity because of the project, according to Joe McDivitt, district director of operations.

The project will be scheduled to prevent any interruption of service.

About 1 million gallons of sewage from some 14,000 homes and businesses served by South Coast flow daily through the 24-inch pipeline, which will be left in place when the proposed new pipeline is installed.

The tunnel is presently unlined and unsupported in several sections, although some sections have been repaired since the tunnel was constructed in 1954. A 750-foot-long section was enlarged and fortified with shotcrete — sprayed-on concrete — or backfilled with sand in 2007. Those emergency repairs will be integrated with the proposed rehabilitation.

It is anticipated that about 29,000-plus cubic yards of material — approximately 4,150 round-trip dump loads — will be removed from the tunnel. Some will be loaded onto a boat, weather and surf conditions to determine the schedule.

Rock and clean fill will go to the district’s property in Dana Point. The majority will immediately be transported to waste material-permitted landfills, eliminating double handling and reducing costs, according to the draft report.

Additional truck trips will be needed to deliver construction materials, bringing the total to an estimated 6,020 round trips.

Construction is expected to take five years.

“We hope to begin construction in September of 2011,” district public information officer Linda Homsheid said.

Part of the year will be spent obtaining a coastal development permit for the tunnel work in Three Arch Bay directly from the California Coastal Commission and a permit for the rest of the work from the city of Laguna Beach, which Homsheid said will be subject to an appeal to the commission.

The district will also be talking to owners of property above the tunnel, seeking an extra five feet of easement, Homsheid said.

Staging and work areas to access the tunnel will be necessary at the district’s Aliso Creek service yard on Country Club Road, Aliso Beach, the beach end Camel Point Drive, Thousand Steps Beach and on South Coast Highway for a new access shaft.

Locations under consideration for the shaft include a vacant lot at Fifth Avenue, a district-owned lot at Fourth Avenue and the Groves Family property at 32201 Coast Hwy.

The shaft, which will provide equipment and materials access to the tunnel, will be 20 feet in diameter, sunk 90 to 100 feet deep and 230 to 359 feet long, depending on location.

A draft EIR for the project was originally circulated in 2009. The draft now in circulation includes revisions to the project, an expanded geotechnical assessment, the addition of historical resources in response to the comments submitted on the 2009 draft and information analyzed in the interim, McDivitt said.

“The district will consider potential impacts and public input on environmental issues when making a decision to proceed with the proposed plan or an alternative,” McDivitt said.

Based on the comments submitted after the initial study and public scoping meeting, the district identified eight areas for full impact analysis: aesthetics, air quality, noise, transportation/traffic, recreation and biological, paleontological , geology/soils and geotechnical resources.

Historical resources were also analyzed because of possible impacts on one of the tunnel access locations in the plan.

The initial study determined that potential adverse effects would be less than significant to agricultural resources, hazards and hazardous materials, hydrology and water quality, land use and planning, mineral resources, population and housing, public services, utility and service systems.

Environmental impact reports, as their name make clear, are intended to inform decision makers, and the general public and responsible or interested agencies, of a project’s potential impacts on the environment, enabling them to make more knowledgeable evaluations. Proposed methods to reduce or eliminate adverse effects can be examined and alternate projects, including no project, considered.

The city, which has its own sewer department, was among the agencies whose comments were sought.

“Council members are very, very supportive of the project,” City Manager Ken Frank said. “It is absolutely essential.”

For more information, visit scwd.org, e-mail tunneleir@scwd.org or contact McDivitt by phone at (949) 499-4555 or by mail at South Coast Water District, 31592 West St., Laguna Beach, CA 92651.