SPECIALTY CIVIL CONSTRUCTION

PROJECT HIGHLIGHT

EASTMAN LAKE LANDSLIDE & PAVING
EASTMAN LAKE, CA

  • Installation of approximately 800 20 ft and 24 ft long post-tensioned SuperRockBolts™
  • Road protection with trench plates and k-rail
  • Repaved the road and sealed slurry before reopening

North Star, the prime 8(a) contractor, selected two primary subcontractors, Great Lakes E&I and Landslide Solutions, Inc. (LSI), to assist with stabilizing a failing rock slope near Eastman Lake. Both subcontractors were selected based on extensive experience and excellent reputations.

 

The U.S. Army Corps of Engineers made a rock cut during the road construction for the Eastman Lake park headquarters access road in the early 1970s. Although the road cut is nearly continuous in this area, episodic rock failures had occurred since its construction. The rock cut slope consisted of 980 lf of near vertical weathered schist and sandstone, from which some wedges had fallen and blocked the roadway below. The rock cut was broken into lower and upper vertical sections. The lower section consisted of the bottom of the entire 980 lf face. The upper section consisted of an upper 280 lf crown in the cliff face. A bench containing a v-ditch separated the upper and lower sections. The average height of the sections was 35 ft. The total estimated surface area of both sections was 51,000 sf.

 

The North Star team conducted mechanical scaling, requiring an equipment combination consisting of a long reach excavator and a traditional excavator with a scaling blanket attachment. Following the mechanical scaling process North Star hand scaled the slope to insure removal of any loose rock material. Approximately 800 20 ft and 24 ft long post-tensioned SuperRockBolts™ were then installed across the rock face and were used to anchor high strength steel rock fall mesh. The road below was protected against damage by placing trench plates and k-rail to catch potential rock fall debris. In addition the road was repaved and slurry sealed before reopening to the public for the July 4th weekend.