as the tides in September did not allow sufficient
ing was widespread. However, it was quickly ad-
testing of the concept. The discharge rate for the
dressed after refueling, and the wetting was not
system was 13% below the theoretical rate, due pri-
thorough. Ponds in Area A, once drained, did not
marily to the length of the discharge line. Results
reflood until the resumption of high flooding tides
from the installation of the tide gate indicated that
on 6 September. Longest continuous nonflooding
marginal flooding tides may be prevented from in-
periods for the various ponds are listed in Table 3.
filtrating into the treatment areas, but further
Table 3 does not tell the complete story. As
study was required.
shown in Figure 11, operation and maintenance
problems with some of the equipment prevented
Full-scale deployment--1998
the full utilization of the nonflooding period. For
Results for the pond pumping remediation
Pond 146, a potential "dry" period of 70 days has
effort can be measured two ways. The first is relat-
been reduced to three partially dry periods of
ed to the pump performance: How dry we are able
approximately two weeks each. Although prob-
to keep the areas and how quickly they are drained
lems occurred with the other systems, none were
after flooding? The second is related to contami-
as widespread as with this system (system 3). Fig-
nant attenuation: How much is the natural attenu-
ure 11 also shows the relationship between Area
ation enhanced, as measured by planted particles,
C/D and Area A. Although a constant stream of
composite sampling, and discrete sampling?
Through the use of the tide gates, flooding of Area
Table 3. Maximum nonflooding peri-
C was almost completely prevented throughout
ods (1998).
the core season (15 May to 15 September). After the
Days not
final flooding tide of the spring on 28 May, the area
Pond
Start
Flood
flooded
was allowed to drain for a day and the pump sys-
tems started. The area was drawn down by 1 June.
Area C
146
1 June*
10 August
70*
The pumping system in Pond 155 was started on
155
2 June
10 August
70
1 June and drawdown occurred within one day.
183
1 June
10 August
71
Pond 146 was never completely drawn down due
Area A
to a lack of a sump for pump unit 3 and the
256 26 June
5 September
72
recharge from a beaver channel nearby. Only one
258
5 September
flooding tide affected the area adversely, occurring
290 29 May
5 September
100
on 10 August. Because the contractor had allowed
* Only areas outside of the previously dredged
the genset in Pond 183 to run out of fuel, the flood-
channel (199496) were not flooded.
5.0
Start Pump
Flood Tide
4.9
Pond 40
4.8
Pond 146
4.7
4.6
4.5
4.4
Shut Down:
O & M Problems
4.3
Shut Down:
Faulty Starter:
Fuel Spill
Maintenance Shutdown
Genset Down
4.2
Figure 11. Water level relationships between Area C and Area C/D.
15
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