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:
ay be used in empirical design methods of rock excavation. 4.5.2 Sampling Coarse-Grained Soils For coarse-grained soils, samples should be taken at depth intervals no greater than 1.5 meters (5 feet). Beyond a depth of 15 meters (50 feet) below foundation level, the depth interval for sampling may be increased to 3 meters (10 feet). Requirements for undisturbed sampling of coarse-grained soils will depend on actual site conditions and planned laboratory testing. Experimentation with different sampling techniques may be necessary to determine the method that is best suited to local soil conditions. Coarse-grained soils containing gravels and boulders are among the most difficult materials to sample. Obtaining good-quality samples often requires the use of trenches, pits, or other accessible excavations into the zones of interest. Standard penetration test results from these materials may be misleading and must be interpreted very carefully. When sampling of coarse soils is difficult, information that may be lost when the soil is later classified in the laboratory should be recorded in the field. This information should include observed estimates of the percentage of cobbles, boulders, and coarse material and the hardness, shape, surface coating, and degree of weathering of coarse materials. DG-1392, Page 17 4.5.3 Sampling Moderately Compressible or Normally Consolidated Clay or Clayey Soils The properties of a fine-grained soil are related to the in situ structure of the soil, and undisturbed samples should be obtained. Regulatory Position 4.5.4 of this guide discusses procedures for obtaining undisturbed samples. For compressible or normally consolidated clays, undisturbed samples should be continuous throughout the compressible strata in one or more principal borings. These samples should be obtained by means of suitable fixed-piston, thin-wall tube samplers (see Appendix F to EM 1110-1-1804 for detailed procedures) or by methods that yield samples of equivalent