Multiple design phases of the project have focused on different engineering components, including a 0.5-mile long segment of new pipeline and lift station and two aerial pipeline crossings over the Eagle River.  The project area is located in a narrow mountain valley characterized by significant large-scale landslide features which extend upslope to the west of the project corridor between 1,000 and 8,000 feet above the highway.  The narrow project corridor, proximity of the river, and extensive landslide history are challenging factors that the design team has had to address in our explorations and design due to the considerable constructability impacts.   

Shannon & Wilson’s scope of services included multiple phases of field explorations over two drilling seasons consisting of geologic mapping, geotechnical borings, and a groundwater monitoring well.  We also performed laboratory testing on soil and rock samples collected during the field exploration program for both index and engineering properties.  Our initial investigation focused on the pipeline and lift station, and included an alternatives analysis related to a deep gravity sewer option that could eliminate the lift station; that option was ultimately discarded.  An additional investigation focused on two pipeline aerial crossings, and involved geotechnical analysis and design related to deep foundations.