Ninyo & Moore Geotechnical and Environmental Sciences Consultants.

Ninyo & Moore provides geotechnical engineering, engineering geology, geophysics, hydrogeology, soil and materials testing, and environmental services.
3202 East Harbour Drive Phoenix, AZ
Phone: 602.243.1600

Fort Peck Dam Spillway Assessment

Location:

Fort Peck, Montana

Scope of Work:

  • Evaluation of 36 Concrete Spillway Panels
  • Rebar Verification
  • Void Detection
  • Condition Assessment (delamination, honeycombing, etc.)
  • Impact Echo Survey
  • Ground Penetrating Rebar Survey

Project Challenge: Our client and the US Army Corps of Engineers needed to evaluate the presence of concrete defects and sub-slab voids developed during spillway operations during a large flood event along this reach of the Missouri River in 2011.

Innovative Solution: Ground Penetrating Radar (GPR) and Impact-Echo (IE) methods were applied at four specified areas located within the Fort Peck Dam Spillway concrete floor. We surveyed the presence of reinforcing steel rebar at 15 client specified concrete core designations, and surveyed the presence of relatively significant intra-slab and sub-slab voids over 36 concrete spillway floor slab panels. We conducted about 43 GPR survey profiles, and approximately 700 IE concrete velocity and depth tests on the specified spillway chute floor slabs. Results were based upon our data interpretations including GPR signal response, IE response, locations, and interpreted geometries, including the approximate presence of geophysical anomalies indicating possible presence of concrete voids, cracks, delaminations, and/or sub-slab voids at our surveyed locations.