Dam Safety Inspections & Program Planning

GZA has extensive experience in performing Phase I Level (as per U.S. Army Corps of Engineers) dam safety inspections and preliminary rehabilitation design evaluations for existing earth embankment, concrete, and stone masonry gravity structures commonly found in the United States. The scope of work involves a site reconnaissance focusing on current dam conditions relating to seepage, unusual movement, structural stability, extent/location of vegetation, and conditions/operation of hydraulic structures (i.e., spillway and outlet works). Initial inspections are supplemented with subsurface exploration programs completed by GZA's in-house drilling company. Soil, concrete, and rock samples are returned to GZA's laboratory where follow-up testing is conducted. Our geotechnical engineers and instrumentation specialists measure critical parameters such as water pressure and deformation on a real-time basis. GZA often uses geophysical techniques such as ground- penetrating radar to locate subsurface anomalies and buried structures. Divers who are registered professional engineers are often used to observe the underwater features.   Phase II Level safety inspections include engineering evaluations involving advanced assessment of seepage and stability, as well as liquefaction and seismic analysis. GZA's staff hydrologists and hydraulic engineers conduct test flood analysis to evaluate the spillway capacity and overtopping potential of the dam. GZA often provides program planning services for owners of multiple dams. We can help prioritize various dam safety actions with respect to safety benefit, risk reduction, cost, schedule, and in-house vs. contracted improvements. GZA has developed specialized computer models to index risks of failure modes associated with embankment dams in order to help prioritize safety improvements.