Tunnel realignment to go before water district board
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.
Support timbers are deteriorating and the earth and rock walls are crumbling. Beams protrude into the tunnel and there is also a 2-foot-wide pipeline running through the tunnel, making it difficult for maintenance workers to maneuver and perform repairs.
No workers have been injured, nor have there been any sewage spills inside the tunnel, according to the district’s website.
The current pipeline, which was installed in 1974, would be encased by a concrete floor throughout the tunnel’s length if the project is approved. A new, 24-inch pipeline would be installed on the concrete floor above the old line.
District crews must enlarge the tunnel to reach solid rock. The tunnel would be lined with concrete and structurally reinforced.
The first part of construction, scheduled for 2014, is creating a 320-foot-long shaft from a staging area on district property at Fourth Avenue and Coast Highway. The shaft, which would allow workers to funnel themselves and equipment, would go under Coast Highway and connect with the existing tunnel in the bluffs, Homscheid said.
The cost would be paid in part by rate increases. Homscheid said it is too early to say how much customers’ bills would increase. The organization is seeking grants to help fund the proposed project.
The district is in price negotiations with Kiewit Infrastructure West Co., the company it chose as the project’s contractor. For the past several years district officials have estimated $50 million to replace the pipeline and stabilize the tunnel, Homscheid wrote in an email. Kiewit submitted a target price of $78 million for five years.
Once the district and Kiewit agree on a price, the figure would go to the board for review and possible approval, Homscheid said.
The addendum to the final EIR is available for public review and comment starting Thursday at the district office at 31592 West St., Laguna Beach, from 7 a.m. to 6 p.m. Mondays through Thursdays. The document will also be available on the district’s website at https://www.scwd.org.
Staff will prepare an additional addendum to the EIR for the 150-foot section at Thousand Steps Beach once the exact location and design details are finalized. This area is being considered because of an extremely low cover (8 to 10 feet above existing tunnel) and possible caving in.
Twitter: @AldertonBryce