Second sinkhole opens in Pacifica

A second sinkhole has opened in Pacifica, more than two weeks after a first sinkhole appeared on the same street and less than two weeks after El Nino storms caused nearby cliffs to erode, resulting in evacuations and prompting city officials to declare a state of emergency.

The sinkhole opened along the Beach Boulevard Promenade near Paloma Avenue, city officials said Thursday.

City Manager Lorie Tinfow said in a statement:

“Another section of the promenade has been undermined along Beach Boulevard. … The new surface opening measures 25 feet long by 3 feet wide by 4 feet deep.”

Tinfow added:

“The good news is that the sea wall below the surface opening appears to remain intact.”

The first sinkhole appeared on Beach Boulevard at Santa Maria Avenue, on Jan. 17. That sinkhole remains open and city officials are preparing to ask City Council for authority to repair it under emergency conditions, Tinfow said in an email.

El Nino storms have been blamed for damaging much of the Pacifica Pier, the Milagra Watershed Outfall and the sea wall along Beach Boulevard.

On Jan. 25, the City Council confirmed a state of local emergency due to damage sustained by the city infrastructure.

That same day, the city declared an apartment building at 310 Esplanade Ave. uninhabitable because of eroding cliffs along Esplanade Avenue. Just days earlier, two other buildings at 320 and 330 Esplanade Ave. had already been declared uninhabitable because of the eroding cliffs.

All three buildings have been evacuated and city officials said the buildings at 320 and 330 Esplanade Avenue will need to be demolished.

The sea wall along Beach Boulevard, north of the Pacifica Pier was constructed in 1984, using system of 5 foot by 7-inch thick concrete tiles that interlock, similar to puzzle pieces. The tiles tie back to the land’s edge through a system of metal straps with a relatively shallow footing, according to city officials.

The sea wall south of the Pacifica Pier was constructed in 1987, using a different engineering design than the wall north of the pier.

For the newer wall, concrete slabs, which measure about 15 feet long by 8 feet wide by 8 inches thick, were installed on deeper concrete footings, making the section of wall stronger and more resistant to wave action or other elements of deterioration, city officials said.