Enclosure (1) TO COMDTINST 16478.12
Results-Demonstration Battery Removals
Several important findings were derived from the demonstration battery removal
program conducted in Tampa Bay, Tennessee, and Puget Sound. First, the number
of batteries likely to be found at aquatic locations is about one-half the
maximum number used during the 20 years of primary battery service at AtoNs.
Few seconday batteries (two of thirteen- hundred) were found in these
locations. Most (62%) batteries were within 5 meters of the base of the AtoN,
and almost all (95%) batteries ever found at any AtoN were within 20 meters of
its base. About one-half of the batteries found in salt water environments
are broken and decaying. Conversely, batteries found in fresh water, or where
sediments are soft and muddy (for instance in Puget Sound), were generally
found intact.
Sediments under battery piles were sampled after the batteries were removed.
The measured mercury levels in these sediments were usually at or below the
background levels, and were within the safe range established by NOAA (ER-M of
0.71 mg/kg). In two locations in Tampa Bay, where a large number of broken
batteries were removed, sediment levels exceeded 5 mg/kg (total mercury). It
is believed that these sediments contained some residue from the outside of
the batteries that accumulated during removal, rather than mercury released
directly from the batteries.
These levels indicate that care must be taken when batteries are removed to
collect attached sediments and biota so that the contaminants will not be
returned to the environment.
CONCLUSIONS
Mercury in spent AtoN batteries is primarily in elemental form. Although a
small portion of the mercury originally in spent batteries (not submerged in
an aquatic environment) was in ionic form; it was released to the environment
and dissolved immediately at the time the battery was discarded. Thus, the
contents of the batteries themselves is relatively harmless.
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