GMU is the Geotechnical Engineer for the Emerald Bay Entrance Widening Project, located in the Laguna Beach area of Orange County.  In order to widen the entrance area, a new slope must be constructed descending from the entrance road to the park area below.  The park area is underlain by alluvium that was found to be soft and susceptible to seismic deformation.  To reduce seismic slope safety factors and deformation to an acceptable level, ground improvement was needed for the project.  Improvements in the form of installation of displacement grout columns into the soft alluvium below the toe of the planned slope was designed.

These displacement grout columns are currently being installed by D.J. Scheffler, Inc.  As shown in the photo, the column is drilled with a piling drill rig that uses a displacement tool to laterally displace the soil into adjacent ground.  This drilling method creates relatively low noise and minimal spoil soils.

The image above shows the displacement tool beginning a new column.  The tool used for this project is 18 inches in diameter.  Standard tool sizes range from 14 inches to 24 inches in diameter.  The piling drill rig is equipped with electronic monitoring systems to track values including torque, depth, time duration, concrete pump pressure and pumping speed.

As the drill stem is extracted, a small door opens at the base of the displacement tool, and concrete is pumped into the column.  Once the displacement column is completed, a strand of #10 rebar is installed in the center of the column using a crane to center the strand.

The finished product (above) may not look exciting, but the effect the grout column improvements have on the soil, and the planned roadway project is significant.  For more information on how GMU can use solutions like displacement grout columns on various projects, check out our web page here.

Happy Friday! To celebrate the end of the work week, we are sharing some photos from a project we are working on in San Diego County.  This project includes installation of a 48-inch bypass pipeline connecting two existing pipelines that service the San Vicente Dam system.  This new pipeline requires construction of a new tunnel through bedrock of the Santiago Peak Volcanics formation.  This tunnel as constructed has an 8.5 foot wide floor with 8.5 feet of vertical height.  A portion of this tunnel is under construction using blasting techniques provided by Drill Tech Drilling and Shoring, who retained GMU to provide blasting consultation.

The photo below shows the contractor preparing the face for blasting:

Approximately 280 feet of tunnel will be blasted using about 50 6-foot rounds.   The following photo shows the tunnel after a blast:

Blasting started in early April and is expected to be complete around the end of May.  For more information on our blasting consultation services, click here.

GMU is currently performing a pavement evaluation of MacArthur Boulevard in Newport Beach. Overseen by our new Director of Pavement Engineering, Roger Schlierkamp, the project is approximately 2 miles long. This evaluation consists of a visual survey, pavement deflection testing, coring, and laboratory testing. Various strategies for pavement rehabilitation are being analyzed by GMU in order to develop a cost-effective repair strategy.

Check out the construction of a 288-foot long arch culvert which will serve as a pedestrian under-crossing in Rancho Mission Viejo. The floor of the culvert was just poured. GMU is providing the geotechnical design and construction services, in addition to special inspection for the reinforced concrete. Stay tuned for updates as the work progresses