Enclosure (1) TO COMDTINST 16478.12
specific pattern of contamination relating to a particular battery". (Hoff
and Beckvar 1993 p1). Determination of an appropriate number of samples and
their spatial distribution was difficult to achieve since the pattern of
contamination was unknown, therefore several assumptions had to be made.
First, the logical area which could be defined as "immediately around the
ATON site" had to be established. A 20-meter area around the based on the
AtoN was selected based the findings of battery reconnaissance operations
conducted in the Chesapeake Bay. Later, results of a demonstration battery
removal program in Tampa Bay supported the selection of a 20-meter field. In
Tampa Bay, 62.5 percent of all batteries found were within a 5-meter radius of
the base of the AtoN; 95 percent were found within 20 meters of its base
(Borener 1994).
The number of samples taken at sites (10 per AtoN) reflects a sampling density
of 126 square meters per sample. Table 2-1 compares the AtoN sampling program
with other sediment sampling programs to show the level to consistency in the
sampling density. Where applicable, the data were divided into (1) "Inner
Zone" areas where the potential for elevated concentration of contaminants was
the greatest and (2) the total area studied. For example, in the AtoN battery
studies, the near-field areas were considered most likely to be affected by
mercury (i.e., Inner Zone). A brief description of each project is included
in Appendix B.
Since the sampling was not intended to be source-point-specific, a stratified
random sampling approach was chosen. This approach reflected NOAA's concerns:
"we recommend against focusing sampling effort near visible batteries: the
batteries may have moved over time, and may not represent all areas of
contaminated sediment; inputs from buried batteries will be unaccounted for;
sampling effort will focus on a few areas and may not represent the area of
concern; and lastly, a battery-focused sample design will likely require
greater sampling effort and provide less useul information for risk
determination than a randomized approach. " (Hoff and Beckvar 1993). Sample
stratification was implemented to reflect the observed distribution of
batteries around the base of the AtoN (Ch2M Hill 1993) (Borener 1994).
2-9
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