- Presence of deep deposits of compressible and liquefiable soils
- Deep Soil Mix ground improvement program
- Innovative use of ground improvement for a safety-related nuclear power plant structure
- 2012 ACEC Engineering Excellence Award winner
Challenge
GZA has provided geotechnical and civil engineering services on 14 Independent Spent Fuel Storage Facilities (ISFSIs) at nuclear power plants throughout the U.S. in since 2002 to address the safe storage of spent fuel at the plant sites since a permanent disposal repository by the federal government is not available. During 2008 and 2009, GZA was retained by Enercon Services, Inc. to provide geotechnical engineering for the design and construction of the Brunswick Nuclear Plant ISFSI. The ISFSI is used for dry on-site storage of spent fuel in Horizontal Storage Modules (HSMs) and consists of reinforced concrete pads (supporting the HSMs), a Heavy Haul Path (to transport the fuel to the ISFSI site) and ancillary operations and security structures.
Solution
As the design Geotechnical Engineer-of-Record, GZA’s responsibilities included evaluation of the dynamic site response during the design earthquake; foundation design for ancillary structures; haul path pavement design; design of the ground improvement; development of ground improvement specifications and details; and evaluation of ground improvement construction QA data. Ground improvement using Deep Soil Mixing (DSM) was recommended to address these issues. DSM involves mixing of cementitious materials with the existing soils using large diameter augers in order to increase the shear strength and stiffness of the soils.
Benefit
Several different DSM column grids were evaluated to select the optimal ground improvement. This project represented an innovative, safe and effective use of ground improvement for an ISFSI foundation design at a nuclear power plant site. The project received an ACEC 2012 Engineering Excellence Award.