CHALLENGING HILLSIDE CONSTRUCTION PROJECTS

 

      

Uphill construction project in Hollywood Hills.  Small, steep hillside with limited construction access.  Foundation contractor, Richard Moe with Hillside Foundation, was able to deal very effectively with the site difficulties through project construction planning and coordination with the various subcontractors.  Soldier piles were utilized for temporary support of vertical excavations within the granite bedrock.  Retaining walls required waterproofing and subdrain installation while working on a steep, limited access hillside.   

  

This custom hillside residence was constructed at the top of Sunset Plaza Drive in the Hollywood Hills.  Construction difficulties included trimming of over-steepened cut slopes around the perimeter of the site and stabilization of a landslide within the fractured granite bedrock.  Normally, granite bedrock is considered an overall stable earth material and very few large scale failures are known to exist.  The landslide developed due to presence of numerous intersecting fracture and joint planes which created a pocket of instability.  The landslide was identified during preliminary site evaluations.  During site grading, trimming of the landslide was attempted, however a large portion of the slope eventually failed during grading.  To correct this condition, a pile-supported retaining wall was constructed at the base of the failure and backfilled at a 2:1 gradient.  Failure debris was removed from the slope.  Rock anchors were utilized to stabilize unsupported joint and fracture planes.  A gunite blanket was provided over the steep sections of exposed bedrock in the upper failure area to help protect the slope from further erosion.  Soldier piles were installed at the top of the slope to protect the residence under construction.

    

Parmelee Geology was hired to evaluate foundation distress which was occurring to a 1920's hillside residence in the Silverlake area of Los Angeles.  Test pit excavations determined that the residence was supported on a shallow, unreinforced concrete foundation supported within creep-prone uncertified fill.  Recommendations were provided for support of the front portion of the residence with a system of friction piles and grade beams.  The images show the initial phases of foundation repairs, beginning with removal of the front portion of the residence foundation system, temporary shoring of the residence and excavation of the new friction piles.

              Parmelee Geology was hired to evaluate this beachfront property on La Costa Beach in Malibu.  The residence was constructed in 1963 and is supported on a system of driven wood piles.  The front three wood piles were replaced with steel-reinforced concrete piles after storm damage in the late 1980's.  The last image shows shoreline erosion which results from daily high tides.  Structures constructed along active shorelines can experience damage due to wave impact, beach erosion and scour.  Properties along La Costa Beach typically have not been provided with bulkheads which can provide substantial protection when constructed properly.