Marquette Lake Dam at Ft. Indiantown Gap

National Guard Bureau | Lebanon County, PA

AEG served as the Prime Consultant for the Preliminary Design of the Marquette Lake Dam Rehabilitation project located in Lebanon County for the Department of Military & Veterans Affairs. This high-hazard dam is part of a facility leased to the Federal Government, National Guard Bureau. The dam is approximately 1,180 feet long and 27 feet high.

The goal of this project was to design the most cost-effective renovations to the dam, spillway, and downstream channel including a protection system to armor the dam breast and spillway during an overtopping situation. The design was completed to meet the requirements of Pennsylvania PADEP’s Chapter 105 Dam safety regulations and withstand the Probable Maximum Flood (PMF).

AEG's services included geotechnical and geophysical investigations, H&H analyses, environmental studies, and surveys. AEG also provided cost estimates for several design and construction options that varied from different rehabilitation measures to a full dam replacement.

AEG performed a geotechnical investigation to determine the engineering properties of the existing embankment of the dam and to provide subsurface data and parameters for the seepage and slope stability analyses to ensure the safety of the dam against overtopping during PMF. AEG produced a Preliminary Geotechnical Engineering Report (PGER) to provide the results of the subsurface investigations and geotechnical analyses.

The geophysical investigations were completed to further define the materials used in the dam and their variability, saturation, and potential for water seepage. AEG employed two geophysical methods- Electrical Resistivity Imaging (ERI) and Spontaneous Potential (SP). The findings of the investigations and AEG’s recommendations were summarized in the Geophysics Report.

AEG’s environmental and water resources tasks involved thorough coordination with the PADEP, environmental and dam permitting, E&SC plan preparation, post-construction stormwater management plans, river mechanics, floodplain assessments, H&H analyses, and others.

AEG continues to provide annual inspections of the dam.