Crowley Environmental and Technical Services LLC

Forensic evaluation of sites or areas of sites can be useful to differentiate wastes or to assign a particular waste to a specific site activity.  There are many tools available for forensic evaluation from simple physical or chemical tests to sophisticated materials testing techniques such as x-ray diffraction and electron microscopy.  My unique background in microscopy, coupled with my knowledge of analytical methodologies, and my familiarity with industrial processes allows me to assemble a customized analytical package to identify the unique characteristics of wastes.  

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One successful example of my forensic experience was with a radioactive material that was unexpectedly encountered on a site.  The material in question was known to have been used as fill in the area prior to the knowledge or understanding of radioisotopes.  The radioisotopes occurred in the feedstock for the industrial process and were slightly concentrated in the process waste due to the extraction of the target minerals.  It was critical to both the management of the material and to assigning costs to the generator that the material be correctly identified.  The waste was known to contain uranium and its decay products, specific unique minerals, phosphorus, and iron, which was added to the process to facilitate extraction of the target minerals.  In order to positively identify the material as the waste in question, an analytical program was tailored to exploit the unique characteristics of the waste.  First, radiological analyses were performed using gamma spectroscopy.  Metals analyses were also performed using standard USEPA analytical techniques; however, the extraction technique was altered to ensure extraction and subsequent quantitation of all metals present, rather than just those extractible by standard techniques.  X-ray diffraction was incorporated because it is the definitive method for crystal and mineral identification.  Finally, scanning electron microscopy was used to view the crystal structure and to chemically identify specific structures in the matrix.  The results showed uranium and its decay products in secular equilibrium, indicating that the waste contained naturally occurring radioactive material rather than radioactive elements that had been altered by selective radioisotope extraction or nuclear reactions, either of which would have made it licensable under the NRC.  The metals analyses showed high concentrations of both iron and phosphorus, which were expected in the waste.  X-ray diffraction revealed the presence of two minerals that are known to be in the waste as well as amorphous material characteristic of melting and quickly cooling rock.  Finally, the scanning electron microscopy revealed that the chemical makeup of the amorphous minerals was consistent with the waste in question.  Taken together, the analyses definitively identified the waste as being from the suspected process, and allowed proper disposal and assignment of the costs to the actual generator.  

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Another option supporting a forensic analysis is using an on-site microscope to identify materials contained in the soil matrix.  This method was used to determine of the source of high lead concentrations in soils remaining where a building had been demolished.  The photo micrographs below show materials identified in soil samples examined on-site.  Photograph 1 is of coal, Photograph 2 is coal ash, Photograph 3 is paint chips found in the soil matrix, Photograph 4 is a metal chip (curl in center), and Photograph 5 is metal chips removed from the soil matrix for laboratory analysis.  The discovery of the metal chips and their subsequent analysis proved to be the source of lead, which was associated with a former machining operation in the building.