About this Project

Tobyhanna Dam No. 2 is located in Tobyhanna State Park and is owned by the Pennsylvania Department of Conservation and Natural Resources (DCNR). It is an earthfill embankment structure that is 18 feet high and 860 feet long, including the 62-foot spillway. This project aims to design the most cost-effective protection system to armor the dam breast and spillway during flooding conditions.

AEG prepared a Site Reconnaissance Report to summarize the results of a background information review and a site reconnaissance for the existing earthfill embankment and areas around the dam.

A geotechnical investigation was performed to determine the engineering properties of the existing embankment of the dam and to provide the subsurface data and parameters for the seepage and slope stability analyses to ensure the dam’s safety against overtopping during Probable Maximum Flood (PMF). AEG performed soils and geological reconnaissance, developed the subsurface exploration program (including coordinating the geotechnical-related field activities and providing full-time inspection during the drilling of the borings), performed in-house laboratory tests on selected soil and rock samples, evaluated the subsurface data, and performed geotechnical analyses such as embankment slope stability and seepage analysis.

AEG then prepared a Final Geotechnical Engineering Report (FGER) to provide the subsurface investigations, laboratory testing, and geotechnical analysis results. The report also included recommendations for the protection system for the dam breast (embankment downstream face) and spillway channel walls.

AEG also completed a Wetland Identification and Delineation for the dam and prepared a report presenting the wetland investigation results. The investigation involved a review of background information sources and mapping and a site investigation.