PACIFIC PALISADES—As part of the Tramonto Landslide Study, Caltrans crews have continued an ongoing geotechnical investigation to evaluate the unstable slope in the Castellammare Mesa neighborhood. The investigations will occur over six weeks, leading to localized street closures and traffic delays from now until the end of October.
Engineers of Caltrans will be executing an 11-hole geotechnical drilling operation along the PCH and surrounding streets; this fieldwork has been ongoing since August. The timeline of the operation runs from August 30 until October 31, which includes land closures and traffic delays. Crews will be operating from 7 a.m. to 6 p.m., Monday through Saturday.
Lane closures will occur on Tramonto Drive and Coperto Drive from September 13 through September 24. Lane closures due to drilling on Posetano Drive will occur from October 12 to October 15. From October 16 through October 23, drilling on Castellammare Drive will cause lane closures at the western boundary.
From October 24 to October 27, drilling on Revello Drive at the western boundary will cause lane closures at the street terminus. The final drilling phase will occur from October 28 to October 31 on Posetano Drive at the eastern boundary with localized lane closures.
City of Los Angeles transportation officials will implement single-lane closures and create 150-foot safety zones around active drilling operations. Work zones will temporarily block traffic, but residents will still be able to walk through, as field crews will pause machinery as needed.
The Castellammare Mesa area is home to at least two landslides, the Tramonto Slide and the smaller Castellemmare Slide, that have been active since 1932 and have moved slowly over the decades. The slide area is three acres, much larger than the portion visible from the highway.
The Tramonto Slide is a deep-seated rotational landslide. Rotational landslides occur along a curved or spoon-shaped surface. There is often a toe of displaced material. Rotational slides often occur because the internal strength of the material is overcome by its own weight. They are usually composed of relatively loose or unconsolidated material. Water has a significant influence.
By Ryley Metten