will continue to threaten wildlife would make the
ducted at ERF in the summers of 1997 and 1998.
remedial process more efficient and less contro-
Pond pumping is a way to temporarily drain the
versial.
ponds, allowing the sediments to desaturate and
the P4 to sublime. Pond pumping does not per-
manently alter the environment the way ditching
Collins, C.M., M.E. Walsh, and M.R. Walsh
(1997) Pond draining and sediment drying as a
and dredging do. Six automatic remote pumping
remediation of white phosphorus contaminated
systems have been designed for Eagle River Flats:
sediments in wetland, Ft. Richardson, Alaska. In
one 1000-gallon-per-minute (gpm) system (pow-
Proceedings, SETAC 18th Annual Meeting, 1620
ered by a 50-kW diesel generator), four 2000-gpm
November, San Francisco, California, p. 124.
systems (80 kW), and one 3000-gpm system (125
Deposition of white phosphorus in the saturat-
kW). The pumping systems consist of two units: a
ed wetland sediments and shallow ponds of the
15-cm (6-in.) open-impeller centrifugal pump on
Eagle River Flats Firing Range on Ft. Richardson,
floats and a generator set (genset) with fuel tanks,
Alaska, has resulted in the deaths of large num-
also on floats. A series of float switches automati-
bers of dabbling waterfowl. Shallow pond areas
cally turns the pump system on and off as water
within Eagle River Flats where waterfowl feed
levels change. Units are sized to allow air trans-
are ideal locations for preserving white phospho-
port into remote ponds using UH60 Blackhawk
rous and are the sites of greatest mortality. If these
helicopters. In 1997, one pumping system was
operated at ERF, and in 1998 all six systems were
contaminated sediments are exposed to the atmo-
deployed.
sphere and allowed to dry, the solid white phos-
The automatic pump system was highly suc-
phorus particles will sublime and the vapor will
cessful in keeping the treated ponds drained for
oxidize. Draining of ponds to expose the contam-
much of the summer. This resulted in extensive
inated sediments is being undertaken in two
drying of the exposed pond bottom sediments.
treatability studies. The first involves permanent
draining through ditching. Because unexploded
Following treatment in 1997, P4 concentrations
ordnance is distributed throughout the area, mili-
decreased by over 88% in the pond treated. Labo-
tary explosives were used during the early spring
ratory manufactured P4 particles were planted in
to excavate an 80-m and a 130-m-long ditch
the sediment during the 1997 and 1998 treatment
between two contaminated ponds and nearby
seasons. The planted particles decreased in mass
drainage gullies. The contaminated sediments
by 50% in 1997, and 60% in 1998 at ponds where
were then allowed to dry. Soil moisture and tem-
pumping was being done. Mallards were selected
perature conditions were monitored to ascertain
as the indicator species to measure the effects of
if conditions were conducive to the sublimation
any treatability studies or remediation actions on
of white phosphorous particles. A second, less
ERF. Overall mallard mortality, calculated from
destructive treatability study uses a large dewater-
telemetry and census data, decreased from 983
ing pump to pump the water out of a contaminat-
ducks in 1996 to 360 ducks in 1997, then increased
ed pond. Water is kept out of the pond through-
to 532 ducks in 1998. The increase of mallard mor-
talities on ERF from 1997 to 1998 can be attributed
out the warmest part of the summer by repeated
to remediation efforts that caused more ducks to
pumping to allow contaminated pond bottom
move from areas being treated to other contami-
sediments to dry out. Soil moisture and tempera-
nated areas not yet treated.
ture conditions were also monitored to determine
sublimation rates of white phosphorous particles.
For both treatability studies, the sediments were
Cummings, J.L., L. Clark, P.A. Pochop, and J.E.
Davis (1994) Eagle River Flats: A potential repel-
sampled at the end of the season and analyzed for
lent for reducing waterfowl ingestion of white
white phosphorous to assess effectiveness of the
phosphorus. In Proceedings, SETAC 15th Annual
remediation strategies.
Meeting, 30 October3 November, Denver, Colorado,
p. 3.
Collins, C.M., M.R. Walsh, M.E. Walsh, J.T.
The U.S. Army has used the Eagle River Flats
Walls, and M.E. Wong (in press) Remediation of
(ERF) on Fort Richardson (Alaska) as an artillery
a white phosphorus contaminated salt marsh:
impact area since 1945. The 1000-ha salt marsh is
Eagle River Flats, Alaska. In Proceedings, 1999
a spring and fall staging area for migrating water-
International In Situ and On-Site Bioremediation
fowl. In August 1981, hunters discovered a large
Symposium, 1922 April, San Diego, California.
number of duck carcasses in the ERF. Since that
Pond pumping treatability studies were con-
23
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