Table 6. Comparative sampling concentrations at DWRC pen 5
(1996 vs. 1998).
WP Concentration (g/g)
WP Concentration (g/g)
Row
Row
column
1996
1998
column
1996
1998
R1C1
0.049
not detected
R7C1
22.9
0.0048
R1C2
0.005
not detected
R7C2
0.039
not detected
R1C3
0.003
not detected
R7C3
0.058
0.0007
R1C4
0.018
not detected
R7C4
25.3
0.0034
R2C1
0.022
not detected
R8C1
8.52
0.21
R2C2
0.002
not detected
R8C2
6.01
not detected
R2C3
0.003
not detected
R8C3
0.015
not detected
R2C4
0.003
not detected
R8C4
0.760
0.0037
R3C1
0.008
not detected
R9C1
0.129
0.0033
R3C2
0.004
not detected
R9C2
0.061
0.0010
R3C3
0.008
not detected
R9C3
1.73
0.089
R3C4
0.016
not detected
R9C4
0.063
0.0010
R4C1
0.102
0.0006
R10C1
0.034
not detected
R4C2
4.30
0.0014
R10C2
0.112
0.0021
R4C3
0.032
not detected
R10C3
19.7
0.19
R4C4
0.012
not detected
R10C4
0.279
0.053
R5C1
0.135
not detected
R11C1
421
0.0029
R5C2
5.38
0.050
R11C2
3.63
0.0024
R5C3
0.551
0.0067
R11C3
1.28
0.84
R5C4
0.010
0.0007
R11C4
0.69
0.0074
R6C1
0.029
0.0055
R12C1
5.24
0.026
R6C2
0.009
0.0015
R12C2
0.616
0.0042
R6C3
0.076
0.0042
R12C3
0.320
0.015
R6C4
0.008
not detected
R12C4
0.337
0.0035
Notes: Grid size is 1.82-m square.
See also Figure 17.
to a larger diameter pipe if the higher flow rate is
can be addressed with the minimum of permanent
required. A 25-cm pipe will reduce the head loss-
disruption to the ecosystem. Biological impacts,
es by approximately two-thirds, thus compensat-
however, have not been monitored long enough to
ing for the increased line length. Additional tide
determine the total impact to the ecosystem due to
gates and further development of the currently
temporary pond draining. Treatment periods will
deployed tide gates will help maximize the effi-
differ based on several factors, including weather
ciency of the remediation strategy.
and tidal behavior. Over the course of a good sea-
The key element to success of this methodol-
son, when flooding tides are small or infrequent
ogy is keeping the equipment operating. This is
and climatic conditions are favorable, contami-
especially critical during periods of flooding
nant reduction can be quite significant. Treatment
tides and heavy rains. The six units deployed in
periods may be as short as three years or exceed
1998 were almost too many to handle at Eagle
five. Finally, it is crucial that equipment downtime
River Flats, due to the remote locations of most of
be minimized to ensure the maximum effect of this
the systems. The presence of unexploded ord-
treatment method on drying.
nance made access difficult and time consuming.
Use of a helicopter sped operations immensely,
RECOMMENDATIONS
but may not be feasible over the course of a full
season due to cost (
||content||
,800/hr).
The development of the semiautonomous pump-
The results of the two-year feasibility study
ing has been an evolutionary one since the first
indicate that pond pumping is an effective strat-
system was received in 1995. Field deployments in
egy for addressing the white phosphorus contam-
1997 and 1998 have led to many improvements in
ination problem in Eagle River Flats. Further
the systems, the methods of deployment, and the
operation of the equipment. However, there is al-
investigation into the effects on the ecosystem
needs to be carried out to determine the impact of
ways room for improvement.
this method. However, of the treatment methods
The lower discharge rate for the system 1
tested to date at ERF, including dredging, drain-
pump, 110 L/s vs. 126 L/s, can be offset by going
22
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