Document: NRC Regulatory Guide
Document ID: a094549d-8685-4dad-b90f-c28c7d279a53
Document Type: regulatory_guide
Title: Geologic and Geotechnical Site Characterization Investigations for Nuclear Power Plants + HISTORY – HISTORY 08/2021 – DG-1392 , Proposed Revision 3 07/2014 – Periodic Review of Revision 2 – Reviewed with no issues identified 02/2001 – DG-1101 , Proposed Revision 2 (Rev. 3)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2119/ML21194A176.pdf
Revision Date: 2023-05
Chapter: 
Section ID: RG-1.132
CFR Part: 
CFR Title: 

Content:
rom one boring to another. The number and distribution of borings needed for such nonuniform conditions are determined by the degree of resolution needed to define geotechnical properties required for engineering design. In locations with sedimentary rock formations, it will be helpful to understand the environment of deposition for the various geologic units at the site in order to understand lateral and vertical variations within the units. The goal of the investigations is to define the thicknesses of the different subsurface materials, DG-1392, Page 15 degree of lateral and vertical variability of the materials, and the range of geologic characteristics and geotechnical properties of the materials that underlie all major structures. If there is evidence suggesting the presence of local adverse anomalies or discontinuities in the subsurface (e.g., cavities, sinkholes, fissures, faults, brecciated zones, lenses, or pockets of unsuitable material), then supplementary borings at a spacing small enough to detect and delineate these features are needed. At locations with limestone, dolostone, and anhydrite, the size, frequency, and depth of voids or caverns should be considered because different mechanisms or dissolution processes may exist. It is important that the supplementary borings penetrate all potentially detrimental zones or extend to depths below which presence of these zones would not influence stability of the structures. Geophysical investigations should be used together with the borings to better characterize subsurface conditions at the site. 4.4.2 Drilling Procedures Drilling methods and procedures should be compatible with sampling requirements and the methods of sample recovery. Many of the methods are discussed in detail in U.S. Army Corps of Engineers Engineer Manual (EM) 1110-1-1804, “Geotechnical Investigations,” issued 2001 (Ref. 19). The top of the borehole should be protected by a suitable surface casing where needed. Below ground surface,