results of these analy- Table 5. Total suspended
RESULTS OF 1995 WORK
ses. For comparison, nor- solids analysis (1995).
During dredging operations in 1995, a total of
mal TSS at ERF is 10 to
TSS
137 sediment samples, 23 water samples, four
20 mg/L, and TSS dur-
Sample
(mg/L)
total suspended solids (TSS) samples, and one
ing flooding events is
spoils line solids content and grain size analysis
15 September 1995
215
1000 to 3000 mg/L* 16 September 1995
sample were taken and analyzed. Each of these
1595
(Bouwkamp 1995).
19 September 1995
611
data categories is discussed below, as well as an
From these data, it is 20 September 1995
850
analysis of the results, an estimate of material
clear that the super-
removed, and a cost estimate for removal.
natant exiting into Area C is not degrading the
water quality of the Flats. It should also be noted
Sample analysis for white phosphorus
that the area in which the Basin is draining is
The large number of sediment and water sam-
heavily vegetated, and thus the solids should
ples should give a reasonable indication of the
drop out more efficiently due to slower-moving
contamination of each material. Table 4 is a sum-
water. Most important, any trace WP in the
mary of the data in Appendix B on the sample
stream should quickly sorb to the organic matter
in the area.
Table 4. Results of dredge sample chemical analy-
ses (1995).
Grain size analyses
Table 6. Grain
No. of
Hits
Range
Average
Grain size analyses were size analysis:
(g/kg)
(g/kg)
samples P4 hits
(%)
done on two samples. The first Spoils sample.
Sediment
137
26
19
0.2266.00
6.16
was a spoils sample taken Diameter Percent
(spoils)
directly from the sampling port
(mm)
finer
Water
23
1
4
--
4
of the spoils line. The second
(supernatant)
0.0327
96.3
was taken from a TSS sample of 0.0208
Total
160
27
17
--
--
90.9
the basin outlet runoff. Results 0.0122
82.6
of the analysis of the spoils line 0.0087
71.8
analyses done for the dredging project in 1995. As
sample are shown in Table 6.
0.0061
60.9
can be seen from the table, about 19% of the sedi-
The spoils sample was taken 0.0029
44.3
ment samples were hits. This is consistent with
0.0013
30
from the spoils line on 27 July
the results of random sampling done by other re-
1995. The sample volume was
searchers at the Flats. The range of concentrations
500 mL, with a weight of solids of 18.2 g. The per-
for the analyzed sediment positive readings or
cent solids is 3.87%, and salinity was 1.1 ppt.
hits is low, indicative of nonparticle hits. This
Grain size from this sample is also graphed in
may be due to the sampling technique. The sam-
Figure 9.
ple port is located halfway to the top of the pipe
The one TSS sample that was examined for
and is perpendicular to the flow of the spoils,
grain size was checked only against the no. 200
thus larger grains and particles may not be drawn
sieve (0.075-mm particle diameter). Only 1% of
through the port. Grinding and mixing of the par-
the sample was retained. Other sieve sizes were
ticles over the 720-m length of the spoils line will
not checked due to the small volume of the sam-
also have an effect on particle size. The water hit
ple and the small particle sizes. We were most
may be attributable to sediments in the basin
concerned with particles greater than 0.1 mm
stirred up during lowering of the weir in the
diameter, as those are most lethal to some water-
retention basin (samples were collected from the
fowl at ERF.†
outfall pipe). It is a single hit that is not of great
magnitude and too small to be dangerous to
Estimated contaminant removal
waterfowl.
The volume of material removed from ERF is
difficult to estimate due to the disturbance of un-
Total suspended solids
exploded ordnance (UXOs) in the dredged area.
Due to the slow settling of the solids suspend-
ed in the water column, supernatant decanted
*
Conversation related to TSS measurements done on dredg-
over the weir and out to the settlement basin was
ing samples, S. Bigl, USA CRREL, 1995.
not of the quality originally anticipated. For this
reason, four samples were taken from the basin
dose size, based on unit weight, M.E. Walsh, USA CRREL,
outlet pipe for TSS analysis. Table 5 shows the
1994.
8
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