SOIL SAMPLE SCREENING BY IMP DATE DRAFTED: 19 May 1978 DOE/ERSP PROCEDURENO.21 APPROVED: I. 2 June 1978 by Paul B. Dunaway (ERSP Manager) Introduction There were several considerations that brought about the need for sereening* soil samples. Some of these were: A. Many subsurface soil samples are required to define the extent of contamination beneath the surfacein specific areas of concern. Large portions of these samples have low activity (84 out of 113 Yuma subsurface samples showedless than detectable activities by lab analysis). Laboratory results are currently the pacing item for DOE activities. Processing large quantities of soil samples containing negligible radioactivity is not the best utilization of lab time for current DOE activities. E. IL Sample screening also allows near to real-time decisionmaking capability in determining the need for additonal samples to adequately define areas of contamination. Screening Location There are some advantages of screening the soil samples at or near the sampling locations rather than at the lab on Enewetak. Screening can be done by IMP equipment in the field or on Ursula. A screening site with low backgroundis preferred. ITk. Procedures A. Soil samples sealed in petri dishes with black plastic tape should be prepared (and labeled properly) at, or near, the field location. Corresponding sample cans should be saved until after screening. Each sample container and corresponding data sheet should include island, stake number, depth, date and other useful information (e.g., special "site" designation such as Yuma, Hustead, Plowing Experimental Area 1, ete.). Petri dishes should be counted (gamma scanned) in numerical order and in order of depth of sample. Counting time should be 5 minutes (300 seconds). The net count from 241Am and 137Cs from all samples should be recorded on the provided data sheet (see specimen attachment). Print results from ealculator for all samples. This short form printout will be the only future reference for any sample with less than 20 net counts.** *As used throughout, screening does not mean passing the sample through any type of particle size separator. Instead, screening means performing a preliminary gamma sean to determine a relative level of radioactivity. ** net count of 20 corresponds to about 1-1/2 to 2 pCi/g 241m. A-21-1