Document: NRC Regulatory Guide
Document ID: 688895c2-d1d9-44f3-9c79-3cf0daa88510
Document Type: regulatory_guide
Title: 
Source: NRC Regulatory Guide Division 4
Source URL: https://www.nrc.gov/docs/ML0037/ML003739541.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-4.5
CFR Part: 
CFR Title: 

Content:
trowel or a thin, flat piece of metal approximately 15 cm wide above the open.sdded front end of the tray. With the metal or trowel In place, the soil outside the tray is scraped off down to the depth of the tray. The separated soil is removed and bagged, and the process is repeated until blocks of soil have been removed to the desired depth. A sample consists of soil taken from a minimum depth of 5 cm. A minimum of five samples should be taken along a straight line transect, each from a separate trench, and composited for analysis. Since it may be desirable to resample the site at a later time, the coordinate distances of the transect should be measured to fixed landmarks to identify the relative position of the transect. The trench method is often used for taking depth profile samples to obtain information on the distribution of a contaminant with depth. C. Factors in Soil Sampling If care is taken, either method works well in fine-textured soils; however, "stony" soils present difficulties. In stony soils, larger scoops are recommended. Larger scoops and hence larger soil volume will minify perturbations caused by stones, which interfere with the progress of the edges of the scoop as it is passes through the soil. A representative depth. however, is more important than a representative width. Areas to be sampled should be undisturbed and should be well removed from dusty roads and from sites that show evidence of previous construction. A distance of no less than 120 m (400 ft) from the outer edge of construction is recommended. When it is desirable to sample soil for the measurement of environmental redistribution of radioactive materials by physical, chemical, and biological factors, a random sampling scheme is preferable to a biased selection of sampling sites. A practical method of selecting sampling sites is by locating them randomly by direction from grid points or other fixed points on an area. Soils should be neither muddy nor dry at the time of sampling: