ural attenuation of the contaminant. The Flats are
ated sediments are then allowed to partially dry,
part of the Ft. Richardson Superfund site, and this
after which sublimation of the contaminant
work was performed in accordance with the U.S.
occurs when the proper sediment dryness and
Government Comprehensive Environmental Response,
temperature are reached. The spoils, sediment,
Compensation, and Liability Act. The primary spon-
and areas dredged are all sampled for analysis to
sor is the U.S. Army Environmental Center, Aber-
assess effectiveness of the remediation strategy.
deen Proving Ground, Maryland. Support was
An ongoing study of the attenuation process in
provided by the U.S. Army Corps of Engineers,
the containment area is being conducted to deter-
Alaska District, and U.S. Army Alaska (DPW-EV).
mine if this treatment strategy is valid.
Three years of operation, including one by a
contractor, indicate that dredging can be an effec-
Walsh, M.R., C.M. Collins, and M.E. Walsh
(1997) Remediation of white phosphorus contam-
tive means to address permanently ponded con-
ination in wetlands using small scale dredging. In
taminated sites. Cost effectiveness in this applica-
Proceedings, SETAC 18th Annual Meeting, 1620
tion using the pilot system developed may be
November, San Francisco, California, p. 124.
problematic.
Deposition of white phosphorus (WP) in the
saturated soils of the Eagle River Flats Firing
Walsh, M.R., M.E. Walsh, and C.M. Collins
(1998) In-situ remediation of white phosphorus
Range on Ft. Richardson, Alaska, has resulted in
in wetlands. In Proceedings, American Society of
dabbling waterfowl die-offs. Deaths through
Civil Engineer--Wetlands Engineering & River Res-
uptake of the contaminant continue, even though
firing of WP rounds was discontinued in 1990.
toration Conference 1998, 2227 March, Denver, Col-
orado, p. 116.
The persistence of WP in the cool, saturated sedi-
White phosphorus has been found to be the
ments of permanently ponded areas on the range
causal agent for massive waterfowl die-offs at the
indicates that, unless addressed in means other
Eagle River Flats impact range on Ft. Richardson,
than natural attenuation, the die-offs will con-
Alaska. Research indicates that in-situ remedia-
tinue for many years. Several remediation strate-
tion of white phosphorus is possible if the sedi-
gies have been demonstrated at this unique site,
ments in which the contaminant persists can be
one of which is small-scale dredging with a
remotely piloted system.
desaturated and the temperature rises to where
A specialized remote control augerhead dredge
sublimation can occur. Several remediation meth-
system was fabricated for the remediation project
ods have been studied at the Flats, the most
using standard equipment. An exclusion device
promising of which is the pumped removal of
was adapted to the augerhead to prevent inges-
ponded water using an automatic remote pump-
tion of unexploded ordnance. Dredge spoils are
ing system developed byCRREL. This paper will
pumped to a containment area where supernatant
describe the system, its deployment, and the
is decanted from the sediments. The contamin-
results of the first year's study.
CONTRACT REPORTS
Bouwkamp, C.A. (1994) Contaminant inventory.
for temperature, dissolved oxygen, pH, oxygen-
In Interagency expanded site investigation: Evalua-
reduction potential, conductivity, and salinity.
tion of white phosphorus contamination and potential
WP was the only contaminant compound found
treatability at Eagle River Flats, Alaska (C.H. Racine
in ERF.
and D. Cate, Ed.). CRREL Contract Report to U.S.
Army Garrison, Alaska, Directorate of Public
Bouwkamp, C.A. (1994) Food chain invertebrates
Works, FY93 Final Report, p. 87110.
and fish: Sediment bioassay. In Interagency
Sediment and water samples were collected
expanded site investigation: Evaluation of white phos-
from 18 sites in ponds and distributaries. Water
phorus contamination and potential treatability at
samples were obtained from two locations in
Eagle River Flats, Alaska (C.H. Racine and D. Cate,
Eagle River. These samples were analyzed for WP,
Ed.). CRREL Contract Report to U.S. Army Garri-
explosives, nutrients, target analytes, and target
son, Alaska, Directorate of Public Works, FY93
compounds. In addition, the water was field tested
Final Report, p. 241257.
35
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