A geotechnical investigation was performed for the repair of a failed MSE retaining wall and cut slope that were constructed for the widening of Adelphi Road.  Both of the failures occurred during a period of heavy rain and snow-melt while the roadway was still being constructed.  A subsurface investigation was performed to evaluate the subsurface conditions to determine the cause of the failures and design for the repairs.  It was determined that the failures were caused by a combination of water-bearing sand layers weakening the slopes and accumulation of surface runoff into the wall backfill affecting the internal stability of the MSE wall.  The repairs for the project included regrading and re-design of the MSE wall and the construction of subsurface drains in the failed slope.

Lab Testing:

• Classification
• Shear Strength

• Improving surface and subsurface drainage.
• Minimizing the need to reconstruct existing MSE wall.