USACE Lower Cragston Dam Engineering Assessment

Princeton Hydro was contracted by the US Army Corps of Engineers (USACE), New York District to perform a Dam Engineering Assessment for the Lower Cragston Dam at West Point. The multidisciplinary approach to this engineering assessment consists of: Geotechnical and Geophysical Investigation & Reporting; Bathymetric and Topographic Survey; Hydrologic & Hydraulic Analysis; Structural Analysis; Seepage and Stability Analysis; and Dam Break Analysis.

In order to successfully and safely perform geotechnical soil borings and rock coring within the dam embankment, a Drilling Program Plan (DPP) was developed by Princeton Hydro. In order to develop a proper drilling scope and methodology, a thorough review of existing documentation was performed including historic engineering plans, dam inspection reports, and Emergency Action Plan. The DPP also required a comprehensive understanding of bedrock and surficial geologic formations in the area. A risk analysis was also performed and the DPP was ultimately approved by the USACE Dam Safety Officer and executed successfully in the field.

Laboratory soil testing was performed at Princeton Hydro’s AASHTO-accredited and USACE-validated soil laboratory. Ultimately, the geotechnical investigation and subsequent soil analysis was used to inform a slope stability and seepage analysis.

The geotechnical analyses, H&H study, structural inspection, bathymetry, and dam break analysis were used to provide USACE, and in turn, West Point, with recommendations for repair options, replacement options, and decommissioning options for the dam.