outside heat source was removed. To test this
D. Cate, Ed.). CRREL Contract Report to U.S.
hypothesis, unsaturated sediments were equili-
Army, Alaska, Directorate of Public Works, FY95
brated at 13C (typical average temperature for
Final Report, p. 249266.
This task was to study the enhancement of
ERF sediments during the first part of June), and
reduction of WP particles in intermittent ponded
then a hot air gun was used to heat the sediments
briefly to 40C. Then, the sediments were cooled
areas by sediment warming. The most important
to 13C and WP particles were recovered. This
condition for loss of WP particles from ERF sedi-
ments is desaturation of the sediments, which
treatment failed to rapidly remove WP from the
occurs in summers with long periods between
sediments. The average WP mass remaining in
flooding tides. A secondary factor is sediment
the heated sediments was not significantly differ-
temperature. Since the vapor pressure of WP in-
ent from the control, indicating that a longer peri-
creases exponentially with temperature and oxi-
od of heating would be necessary to accelerate
dation is more likely at higher temperatures, loss
WP loss. However, the energy requirements for
of WP particles can be significantly accelerated by
prolonged heating in situ would be prohibitive.
warming unsaturated sediments.
Given that intrinsic remediation is occurring in
A field study was performed to test the effec-
some parts of ERF in areas that naturally desatu-
tiveness of passive solar warming techniques on
rate, ways to enhance natural drying should be
increasing sediment temperature and promoting
employed where possible before active methods
the loss of planted WP particles. One technique
of raising sediment temperatures. A third task
tested was the application of black sand to change
was to study the reduction in size of WP particles
the surface albedo. Also tested were two types of
following pond drainage. This was conducted in
synthetic row covers (a spun-bonded polyester
conjunction with the pond drainage treatability
and a porous polypropylene) commonly used in
study by C.M. Collins. Along a transect through
agriculture. The row covers transmit short-wave
the intermittently and permanently flooded areas
(3002500 nm) solar radiation and trap long-
of the Bread Truck Pond, WP particles were plant-
wave radiation (4000 nm) from the sediment sur-
ed in May at a depth of 5 cm, and the sediment
face, producing a greenhouse effect. Sediment
moisture and temperature were monitored at 5-
temperatures were monitored at a depth of 5 cm,
and 10-cm depths at sites. Because of procure-
and all three treatments slightly increased the
ment delays, the pond was not drained and sedi-
sediment temperatures relative to the controls.
ments remained saturated throughout the sum-
Because of monthly flooding tides during the
mer.
summer of 1995 and frequent rainfall during July,
A fourth task was to study the reduction in size
August, and September, sediments were saturat-
of WP particles in dredge spoils. This was con-
ed except for a few days prior to the June flooding
ducted in conjunction with the dredging treat-
tides. None of the treatments appeared to signifi-
ability study by M.R. Walsh. To determine if the
cantly inhibit evaporation during this brief peri-
moisture levels and temperatures of the spoils
od of favorable drying conditions. The amount of
reach those conducive for decontamination, mon-
time when sediments were unsaturated was so
itoring sites were set up at four locations within
short that most WP particles remained essentially
the basin, and when dredging was completed for
unchanged, except for a few particles under one
the season in September, WP particles of known
of the row covers and one particle in the control
mass were placed at known locations. The resi-
plot. These results show that row covers are a tool
due from these particles will be recovered next
that may be used to raise sediment temperatures,
spring.
but attention must be focused first on enhancing
desaturation of the sediments using methods
Walsh, M.E., C.M. Collins, and R.N. Bailey
such as temporary pond drainage.
(1996) Intrinsic remediation of WP particles in
A laboratory experiment was also performed
intermittent ponded areas of ERF. In Interagency
using a more aggressive method to heat sedi-
expanded site investigation: Evaluation of white phos-
ments with planted WP particles. The purpose of
phorus contamination and potential treatability at
the experiment was to test the hypothesis that
Eagle River Flats, Alaska (C.H. Racine and D. Cate,
heating the sediments would increase the vapor
Ed.). CRREL Contract Report to U.S. Army,
pressure of the WP sufficiently to initiate oxida-
Alaska, Directorate of Public Works, FY95 Final
tion, which in turn would generate heat to sustain
Report, p. 231248.
continued sublimation and oxidation after the
69
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