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R9 Laboratory SOP 150
SOIL AND SEDIMENT HOMOGENIZATION
Summary
This SOP describes the homogenization procedures performed at the EPA Region 9 Lab for soil and sediment samples prior to analysis for metals, semi-volatile organics, or other parameters which are not unduly impacted by exposure to air or agitation of the sample. This excludes sample aliquots which will be analyzed for volatiles. RCRA waste samples are not included in these procedures, nor are solid matrices such as concrete, rocks or pebbles, or other samples which do not conform to the general description of a soil or sediment.
As soon as practical after receipt, soil and sediment samples are inspected for compliance with the general description of a soil (as would be understood by a layman and not a geologist). Rocks or pebbles, sticks, leaves or other material not considered to be part of the sample are removed and the remaining material thoroughly homogenized. When possible this mixing will be accomplished in the original sample container. When the soil volume prevents adequate mixing, the sample will be quantitatively transferred to a larger container for mixing. In the event that several sample containers are to be treated as one sample they will be emptied into a tray, mixed thoroughly, and then transferred to a suitably sized glass container. The determination of percent moisture and soil pH (if required) will be completed immediately after homogenization.