GAI provided design and construction phase services for six active landslide sites across Wayne County, including environmentally sensitive sites along the Delaware River. These active landslides had caused pavement failure and threatened mobility in areas of the county with long detour times. Design solutions selected for these extremely steep slope areas included rock benching, soil nail and geonet structures, a post and lagging wall, and a micropile retaining structure. Project delivery took place using Design-Build methodology and successfully restored these sites to full operability.

The geotechnical investigation included test borings and installation and monitoring of inclinometers to obtain deep-seated slope movement data and determine the optimal solution to correct each slope stability issue. For most sites, the District required maintenance of one traffic lane during construction due to extremely long detour lengths. GAI’s geotechnical and structural designs included temporary provisions to maintain traffic and reduce required excavation. The projects also involved reconstruction of the adjacent roadway structure. In most cases, the lane adjacent to the failed edge was a full depth reconstruction, while the interior lane was milled and overlaid. New guide rail was also installed throughout.

GAI’s design services included right-of-way investigations, geotechnical investigations, utility investigations, preliminary plans, preliminary structure designs, and plans, specifications, and estimates (PS&E) packages. During the construction phase, GAI provided construction consultation, shop drawing reviews, final plans review, and structure design and plan reviews.