A dual force main sewer pipeline is needed that would extend from the Venice Pump Plant at 140 Hurricane St. on the Marina Peninsula in the City of Los Angeles to Playa del Rey, also in the city, and provide assistance to the existing pipeline that conveys sewage to the Hyperion Treatment Plant at the southern end of Playa del Rey, said City of Los Angeles Department of Public Works project manager Sean Zahedi in a presentation of the proposed project to the County of Los Angeles Marina del Rey Design Control Board at its Thursday, April 24th meeting in Marina del Rey.
The final stage for public review of the project has ended and the project is “calendared” to be heard by the Los Angeles County Public Works Committee, according to Jim Doty, an Environmental Management Division of Public Works supervisor.
The new pipeline, 52 inches wide and two miles long, would connect with a sewer line at Vista del Mar Lane and Waterview Street in Playa del Rey, near the Hyperion Treatment Plant. It would also allow inspection of the original pipeline.
Although it was not mentioned specifically at the meeting, the pipeline would be drilled under the county Marina del Rey main channel.
The most efficient and least environmentally invasive pathway of the new pipeline would travel underground beneath Via Marina and Marquesas Way in the county jurisdiction of Marina del Rey, said Zahedi.
The new sewage pipeline would be installed underground to assist an existing 48-inch wide pipeline that was installed in the late 1950s and has severe conveyance limitations, said Zahedi.
He told the audience that the original 48-inch pipeline was built of concrete and clay in the late 1950s and has never been inspected because it has been in use continuously and there is no other pipeline which can take over pumping while the original pipeline is shut down.
The new pipeline would be encased in a 72-inch steel pipe, and lining the original pipeline is also being considered.
The presentation was titled “Wastewater— we’re all in it together,” and the project is considered proactive and environmentally significant, since there have been no leaks or breaks in the aging pipeline, but time and wear are against that record being maintained, said Zahedi.
Doty said his division looks for opportunities for environmental betterment, and while they always restore disturbed areas, they will listen to suggestions for a different style of restoration.
Zahedi said the California Coastal Commission is concerned about a possible climatic event and wants a second location for a sewage pipe in case of sewage discharge.
During wet weather, both pipes would be utilized.
Four different scenarios, along with pros and cons, were considered — beach alignment, utilizing Pacific Avenue, using Via Marina/Marquesas Way, or doing nothing, according to Zahedi.
The Venice Beach alignment would include 8,500 linear feet of “microtunneling,” 1,800 feet of “cut-and-cover,” and cost $47 million, not including the cost of erosion protection and easement costs.
Cut-and-cover is a simple method of construction for shallow tunnels where a trench is excavated and roofed over.
Micro-tunneling is defined as “pipe jacking,” employing a remote-controlled tunneling machine. Pipe jacking is the principal of pushing a rigid pipe through the ground into a tunnel bore that has been pre-excavated.
Micro-boring uses tunnel-boring machines to automate a much deeper tunneling process than cut-and-cover, with sensors alerting the work crew if the machine strikes something underground that is not part of the material to be excavated, and it requires management.
The only positive aspect of a beach alignment option would be the minimal impact on traffic, parking and utilities, said Zahedi.
The negative aspects include disruption of the least tern bird colony, recreational impacts to beachgoers, longer construction duration, future beach erosion and operational concerns.
The Pacific Avenue alignment would include 8,200 linear feet of micro-tunneling, 1,800 linear feet of cut-and-cover, and cost $50 million.
Positive aspects of utilizing Pacific Avenue include that there would be no easement costs, as it is entirely within the City of Los Angeles right-of-way; it avoids the least tern colony; it is the shortest route in linear feet; and there are few utilities on Pacific Avenue.
Negative aspects are major transportation/parking impacts, difficulty in locating a working pit north of the channel and major opposition to the project, Zahedi said.
The Via Marina/Marquesas Way route would include 8,600 linear feet of micro-tunneling, 1,800 linear feet of cut-and-cover, and cost $54 million. It also involves passing through the unincorporated county Marina del Rey jurisdiction.
Positive aspects are that it would follow a wide roadway (four-plus lanes), have no parking impacts, involve fewer residential egress opportunities off Via Marina, have no impact on least terns, have sufficient location for a working pit north of the channel, and that opposition is likely to be less.
Identifying former oil wells is also a priority, but Via Marina has fewer old oil wells than the other areas considered, Zahedi said.
Zahedi said city staff is aware of the traffic impact, the cost and delay of obtaining Los Angeles County easements and the small area for the working pit at Grand Canal.
Susan Cloke, chair of the Design Control Board, expressed her gratitude to Zahedi for initiating the project, saying that the aging infrastructure is in serious need of repair.