area triggered an investigation of the causes of
Walsh, M.E., S. Taylor, B.D. Roebuck, and S.I.
mortality. With the discovery of white phosphorus
Nam (1995) Analytical methods for white phos-
from smoke rounds as the causal agent, a large,
phorus. In Proceedings, SETAC 16th Annual Meet-
unprecedented multifaceted remedial inves-
ing and Second SETAC World Congress, 69 Novem-
tigation was initiated. Studies at the Flats can be
ber, Vancouver, B.C, p. 337.
categorized as either ecological assessments or re-
There is no standard analytical method for
medial investigations. Ecological assessments
white phosphorus (P4) in environmental matrices.
considered the physical and biological dynamics
To determine white phosphorus in sediments,
of the Flats and the impact of these factors on the
water, and animal tissues, we are using an analyt-
presence of white phosphorus and vice versa.
ical method based on solvent extraction and gas
Remedial investigations centered around either
chromatography with a nitrogen-phosphorus
removal for treatment in a controlled environment
detector. For sediments and tissues, method detec-
tion limits (MDL) of less than 1 and 10 g/g, respec-
or in-situ remediation or burial. Dredging is
included in the first category. The objective of the
tively, were achieved by extraction with iso-
experimental dredging project at Eagle River Flats
octane. For water, pre-concentration of the sol-
is the removal of white-phosphorus-contaminated
vent extract is required to detect P4 at the water
sediments from the Flats for treatment. The pres-
quality criteria for protection of aquatic organisms
(0.01 g/L). Because of the high vapor pressure of
ence of UXOs and the quality of the environment
are complicating factors. Dredging is selectively
P4, a non-evaporative pre-concentration step is
applied to those limited areas where white phos-
used. P4 is extracted using diethyl ether (10:1
phorus is found, and conducted in such a manner
water:solvent). The ether phase is collected, then
as to minimize the environmental impact both
reduced in volume by shaking with reagent-
while dredging and in the event of the detonation
grade water to dissolve excess ether. A pre-con-
of a UXO. Specialized equipment obviously is
centration factor of 1000 is obtained without heat,
needed to carry out this task. A small augerhead
minimizing loss of P4, by volatilization. Using
dredge was modified for remote control opera-
this pre-concentration procedure, an MDL of less
than 0.01 g/L was achieved. To minimize use of
tion, using video feedback to the shore-based op-
erator. The operator is stationed on shore in a
solvents, solid phase microextraction (SPME) may
hardened shelter that was tested by detonating a
be used to screen samples for P4. Exposure of a 100
m polydimethylsiloxane phase to the headspace
105-mm HE round 35 m from the cab. Hydraulic
fluid is vegetable based and nontoxic to prevent
above sediment, water, or tissue samples for 5 min-
unacceptable pollution in case of spillage. Spoils
utes, followed by thermal desorption in the injec-
from the dredging operation are pumped to a spe-
tion port of the gas chromatograph, provides sensi-
cially designed retention basin located on the
tivity similar to that obtained by solvent extraction.
nearby explosive ordnance disposal pad. The
Since this method is based on equilibrium parti-
retention basin is used to decant supernatant from
tioning between the sample, headspace, and solid
the spoils for eventual remediation of the sedi-
phase, response is matrix specific. The analytical
ment. For effective remediation and to lower the
method for sediment and water will be proposed
risk of a UXO detonating in the pump or along the
for inclusion in the EPA Office of Solid Waste SW
spoils line, a method of excluding UXOs from the
846 Update III as Method 7580: White Phosphorus
spoils stream is needed. After experimenting with
by Solvent Extraction and Gas Chromatography.
several exclusion methods, we devised a cutter
and grate system for the augerhead that success-
Walsh, M.R. (1996) Dredging Eagle River Flats:
fully excluded UXOs while effectively processing
Remediation study in an active impact area. In
sediment and vegetation. This work was success-
Proceedings, 1996 UXO (Unexploded Ordnance)
ful enough that the remediation study for this su-
Forum, U.S. Department of Defense Explosives Safety
perfund site has been moved to a removal action.
Board, 2628 March, Williamsburg, Virginia, p. 266
The work is scheduled to be turned over to a pri-
274.
vate contractor for the 1996 deployment.
Remediation in closed impact areas is hazard-
ous because of the presence of unexploded ord-
Walsh, M.R. (1996) Dredging in an impact area on
nance (UXOs). The problems with remediation of
Eagle River Flats, Ft. Richardson, Alaska. In Pro-
active impact areas are compounded by the infu-
ceedings, AMREM '96 Conference, 2731 May, Albu-
sion of fresh UXOs. At Eagle River Flats, Alaska,
querque, New Mexico, p. 401.
massive waterfowl die-offs at the Army's impact
33
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