South Coast Water District board members plan to vote later this month on a proposal to realign a portion of a 2-mile tunnel that houses a sewage pipeline in South Laguna.
The district's tunnel stabilization and sewer pipeline project covers an area from Three Arch Bay north to Aliso Creek Beach and handles 1-million gallons of sewage per day.
The district wants to realign two portions of the tunnel: a 725-foot span under the bluffs at Three Arch Bay and a 150-foot section under the bluffs north of Thousand Steps Beach.
The 725-foot realignment is going before the board of directors March 28 as an addendum to the environmental impact report. The public meeting begins at 6 p.m. in Dana Point Council Chambers, 33282 Golden Lantern.
The 6-foot-tall tunnel, made of earth and rock and shored up in a few areas with timber beams, houses a 24-inch-wide sewer line that carries wastewater from South Laguna and north Dana Point to the coastal treatment plant in Aliso Canyon.
FOR THE RECORD:
An earlier version of this story incorrectly reported the tunnel was made of reinforced plastic.
District officials consider the 59-year-old tunnel unsafe, deteriorated, under-sized and say it could break, releasing sewage onto the beach, according to a project description on the district's website.
"We can't let [the pipeline] break on the beach," said Joe McDivitt, the district's director of operations who has been with the organization since 2003.
In 2007, the district stabilized and enlarged a 400-foot segment of the tunnel as part of an emergency repair project at Thousand Steps Beach, which took eight months and cost $6.18 million.
Engineers determined that a portion of the tunnel will need to be realigned away from the coastal bluffs and placed under South La Senda Drive in Three Arch Bay, according to a district staff report.
The tunnel's diameter would increase to 9 foot 9 in this area compared with the remainder, which McDivitt said would measure 8 1/2 feet.
The district needs additional 5-foot easements to the existing underground easements.
As of Monday, the district had acquired 161 of 189 easements from property owners above the bluff, Linda Homscheid, the district's communication officer, wrote in an email.
The district held a community meeting about the tunnel realignment at the Three Arch Bay clubhouse Feb. 19, with about 20 residents of the gated community in attendance, Homscheid said.
McDivitt explained the proposed realignment at Three Arch Bay during a walk-through with the Coastline Pilot.
"A bulkhead closes off the south section [500 feet]," he said. "The tunnel in that area is not steady. They backfilled it with sand to protect the pipe."
The tunnel was originally hand-dug and blasted from the cliffs in 1954. At the time there were few homes on the south Laguna bluffs. As more homes and residents arrived, the original 21-inch sewer line inside the tunnel was replaced with the current 24-inch line.
On average, the tunnel is 6-feet wide and tall, but much smaller in many places, according to the project description.