Map scenarios M-2A and M-2B represent different spatial structures with both small and large scale distributional heterogeneities. These examples are based on a more extensive analysis of ISM conducted for USACE and discussed in a separate report (Hathaway and Pulsipher 2010). The data are based on results of site investigations involving measurements of concentrations of RDX and HMX in (discrete) bulk surface soil samples. The two histograms in Figure A-3 show each of these sites in 2-D histograms with a square-root-transformed count axis to improve the visualization of the tail values. With a standard count axis shown, these distributions would look even more extreme. Their respective means are marked with a dotted green vertical line.

Figure A-3. Spatial distributions and histograms of concentrations for two simulated sites.6

6The plots on the left represent a distribution of HMX (mg/kg) and the plots on the right site represent a distribution of RDX (mg/kg) from which increments will be collected. Obstructions such as large rocks and paved roads are excluded to simplify the automation of ISM sampling as well as to simplify the calculation of the population parameter (i.e., “true mean”) from which performance metrics are determined.