Garrapata State Park, Carmel-By-The-Sea

Project: Landslide Repair, Sculpted Shotcrete Wall With Tieback Anchors

Client: California American Water

Location: Garrapata, CA

Design Engineer: Soil Engineering Construction, Inc.

Structural Engineer: Tuan & Robinson Structural Engineers

Contractor: Soil Engineering Construction, Inc.

Geotechnical Consultant: AECOM, Haro Kasunich & Associates, Inc., and Soil Engineering Construction, Inc.

Project Description:

A slope failure occurred directly downslope of two critical infrastructure water tanks providing service for the Carmel-by-the-Sea area. Given how close the slope failure was to the water tanks, they were in a threatened position for becoming undermined. Subsequently to geotechnical work performed by AECOM and Soil Engineering Construction, it was determined that the methodology to stabilize the water tanks would be to install a laterally anchored shotcrete retaining wall.

The job site posed many challenges. The only access to the site is via a winding, single lane, dirt access road. This posed restrictions on which type of equipment SEC could use. As well, the site is home to a variety of protected plant and animal species, and so SEC staff had to be biologically trained to avoid these species and our crews took extreme care to protect wildlife.

SEC crews installed drilled piers and a grade beam to provide shoring for the tanks while construction was underway. The slope was scaled of loose landslide debris, after which SEC installed lateral tieback anchors into the hillside. Given the access constraints, our crew drilled these tiebacks from a crane mounted man-basket. After tiebacks were installed, SEC crews tied rebar and installed a structural shotcrete mat. This was then covered with a stained and sculpted shotcrete face, so as to make the retaining wall resemble natural rock formations.