Table 5. Results of discrete sampling at Site 883 and Miller's
Hole, Area C.
a. Distribution of WP concentration ranges for 41 samples at Site 883.
Percentage of Samples
Conc.
(g/g)
19 Aug 1992
19 Aug 1994
17 Sep 1995
3 Sep 1997
<0.001
37%
59%
68%
98%
0.001 to 0.099
41%
29%
29%
2%
0.1 to 9.9
12%
10%
2%
0%
>10
10%
2%
0%
0%
b. Concentrations found at Miller's Hole, a crater
produced by the detonation of a WP UXO.
WP Concentration (g/g)
Days since
Sampled
explosion
Center
Rim
20 May 92
0
2,394
979
21 Aug 92*
93
184
0.00427
27 Aug 93†
464
81.5
0.00177
30 Aug 94
832
9.5
not detected
17 Sep 95†
1215
166
0.0006
3 Sep 97
1932
1.6
not detected
25 Aug 98
2288
0.037
not detected
*Crater under water when sampled.
† Crater under water all summer.
tion in the surface sediments at this intermittently
there. Finally, two composites were formed from
dry site (Site 883) is obvious when the data are pre-
subsamples taken along the east side of the pond
sented as a percentile plot (Fig. 16). The y axis is
where previous sampling showed some contamina-
presented as the log of concentration (g/kg) to
tion. Again, confirming previous discrete sampling,
show the wide range in concentrations detected.
we found low concentrations of white phosphorus
Zero on this log scale is equivalent to 1 g/kg or
in just a few samples (three out of 44 composite
0.001 g/g. This plot shows the yearly decline in the
samples).
percentage of samples that had concentrations
greater than 0.001 g/g, and a general decline in the
Discrete sampling in Area C
maximum concentrations detected.
Discrete samples were collected from previously
In the three samples that had detectable white
identified hot spots. Site 883 was first sampled in
phosphorus in 1997, the concentrations are too low
May 1992 and had a white phosphorus concentra-
tion of over 200 g/g. White phosphorus concen-
to contain white phosphorus particles that could
pose a threat to waterfowl. The surface sediments
trations in samples taken at 1-m intervals radiating
at this site can be considered remediated and
out from this site on 19 August 1992 showed
future resampling of the surface sediments is
extreme spatial variability. Most of the 41 samples
unnecessary. In 1998 we collected subsurface sam-
had measurable concentrations of white phos-
ples down to 30 cm at Site 883 and a second set 2 m
phorus (only 37% of the samples were less than
0.001 g/g [Table 5]). Since August of 1992, sedi-
east. The subsurface samples showed little con-
tamination (one positive at 10-cm depth). Because
ments in this part of Area C were desaturated dur-
firing of white phosphorus munitions was sus-
ing the summers of 1993, 1994, and for prolonged
pended in 1990, at least eight years have passed
periods in 1997 and 1998. When sampled in Sep-
since this intermittently flooded location was con-
tember of 1997 in the same pattern as was done in
taminated. It is now remediated.
1992, 1994 and 1995, 98% of the samples were less
then 0.001 g/g. Only three samples contained
The location of the DWRC pen 5 is within the
permanent pond of Area C and the sediments have
detectable white phosphorus. These samples were
located 2 m east (0.0006 g/g), 3 m east (0.068 g/
been covered by water since the cessation of firing
g), and 1 m southeast (0.0007 g/g) from the center
of WP munitions. We intensively sampled this
location in 1996 by taking discrete samples at the
point at Site 883.
nodes of a 1.82-m square grid four columns wide
The decrease in white phosphorus contamina-
20
Previous Page
