In late August 2010, GZA responded within one day to the site to make an initial assessment and recommendations for emergency response to a roadway embankment that had experienced a rotational slope movement during construction activities. GZA supported the Maine DOT team in assessing stabilization activities to protect an adjacent house threatened by the movement and to recover a 65-ton crane, power pack and vibratory pile hammer buried in the failed slope.
GZA developed a subsurface exploration program, monitored explorations, and developed a laboratory testing program to assess the shear strength and stress history relationship for the marine clay located in the heart of the failed slope. GZA utilized the analysis package Slope-W to back-calculate the initial failure, then assessed several alternatives for stabilizing the slope.
Recommendations were made for stabilization by relocating the road and residence, cutting the slope height, reducing the slope angle, and taking advantage of the stabilizing effects of the material deposited at the toe of the slope. Laboratory testing and a report of the assessment were completed in fall 2010, and the GZA / Maine DOT team was able to open the road in December 2010. GZA completed the work within budget and met very aggressive schedule to help get the roadway open as quickly as possible, yet provide a stable, environmentally appropriate long term solution.