SOIL SAMPLING AND ANALYSIS FOR VOLATILE ORGANIC-COMPOUNDS

Concerns over data quality have raised many questions related to sampl ing soils for volatile organic compounds (VOCs). This paper was prepar ed in response to some of these questions and concerns expressed by Re medial Project Managers (RPMs) and On-Scene Coordinators (OSCs). The f ollowing questions are frequently asked: 1. Is there a specific device suggested for sampling soils for VOCs? 2. Are there significant losse s of VOCs when transferring a soil sample from a sampling device (e.g. split spoon) into the sample container? 3. What is the best method fo r getting the sample from the split spoon (or other device) into the s ample container? 4. Are there smaller devices such as subcore samplers available for collecting aliquots from the larger core and efficientl y transferring the sample into the sample container? 5. Are certain co ntainers better than others for shipping and storing soil samples for VOC analysis? 6. Are there any reliable preservation procedures for re ducing VOC losses from soil samples and for extending holding times? G uidance is provided for selecting the most effective sampling device f or collecting samples from soil matrices. The techniques for sample co llection, sample handling, containerizing, shipment, and storage descr ibed in this paper reduce VOC losses and generally provide more repres entative samples for volatile organic analyses (VOA) than techniques i n current use. For a discussion on the proper use of sampling equipmen t the reader should refer to other sources (Acker, 1974; U.S. EPA, 198 3; U.S. EPA, 1986a). Soil, as referred to in this report, encompasses the mass (surface and subsurface) of unconsolidated mantle of weathere d rock and loose material lying above solid rock. Further, a distincti on must be made as to what fraction of the unconsolidated material in soil and what fraction is not. The soil component here is defined as a ll mineral and naturally occurring organic material that is 2 mm or le ss in size. This is the size normally used to differentiate between so ils (consisting of sands, silts, and clays) and gravels. Although nume rous sampling situations may be encountered, this paper focuses on thr ee broad categories of sites that might be sampled for VOCs: 1. Open t est pit or trench. 2. Surface soils (< 5 ft in depth). 3. Subsurface s oils (> 5 ft in depth).