Canvas Townhomes are located in a valley bottom and the hillside above it. The benches where the townhomes are located were created with cut and fill construction with retaining walls maximizing the bench size. Canvas maintenance personnel observed significant distress in one section of the complex’s retaining walls which supports the cut over a parking area. The retaining wall is a mechanically stabilized system with a wire mesh facing which is backfilled with small sized rip rap rock. The distress was in the form of bulging in the walls to the point where sections of the facing protruded several inches beyond the underlying sections. At multiple locations the mesh facing was also failing.
Upon inspection by Triad, the owner closed off the area of the parking at Triad’s request and engaged Triad to survey the area and conduct a subsurface exploration. As part of our work we prepared an alternatives analysis with costs to aid the owner in selecting a proposed fix. The selected fix was the construction of a cantilever soldier beam and lagging wall in front of the existing wall with a height of 15 feet and a length of 170 feet. Based on observed conditions, the MSE wall above this height was not showing distress and by limiting the wall height to 15 feet the distress section of wall was able to be replaced with limited construction time and cost compared to other alternatives.
Triad proceed with developing drawings and specifications for design-build construction to accelerate the project and identified contractors for the wall construction. The design-build approach provided contractors with the ability to use the materials and systems that are most readily available to them minimizing construction time and costs. Triad aided our client with evaluation of the contractor bids, technical review of the design and construction inspection along with material testing.