for the overall remediation of contaminated
37 m. The structure sustained only minor damage
ponded areas was to address small, one-hectare
due to shell fragmentation during the tests (Walsh
sites each year, reducing the impact of any one
and L'Heureux 1995). In the test where damage
dredging season and allowing previously dredged
occurred, the round was placed on a wooden crate
sites to begin recuperating during operations in
approximately 0.6 m above water level, with the
the out years. Finally, we had to plan for the worst:
back of the round pointed directly at the cab. This
a detonation of a large caliber UXO by the dredge.
was considered a worst-case scenario by Captain
Specifications were written such that a loss of a
Paul Arcangeli of the 176th EOD Detachment at
fixed volume of hydraulic fluid would trigger an
Fort Richardson, who supervised testing.
automatic shutdown of the system. In addition,
Minimum distance to the dredge during active
the fluid used is biodegradable and nontoxic, so
operations is 40 m. Therefore, to allow the opera-
spills should not adversely affect the environment.
tor to observe the dredging operation, a remote
The dredge power supply, a diesel generator set,
high-resolution wireless CCD video system is to
is located on shore to minimize problems caused
be incorporated. Transmitted along with the video
by petroleum, oil, and lubricant (POL) spills.
signal are the output of vital operating sensors,
such as the various process pressures. This will
allow the dredge operator to conduct operations
Ordnance
The presence of UXOs is the other major de-
as if he were onboard the vessel.
sign consideration. Using a defect rate of 5%, an
Separate from the dredge, a Health and Safety
estimated 10,000 unexploded rounds may be
Plan (HASP) was required by the Fort Richardson
present in the Flats in various degrees of decay
Safety Office due to the hazards involved in the
and sensitivity. There is no safe way of getting even
dredging operation. This document includes sev-
a rough estimate on distribution and densities of
eral pages of material specific to the dredging op-
these UXOs. Therefore, the dredge was specified
eration. Before the commencement of active dredg-
to minimize the structural and financial impact of
ing activities, the HASP was approved by a repre-
the detonation of a round during operations. The
sentative of DPW and the chief of the Fort
dredge was specified as modular in design to fa-
Richardson Safety Office.
cilitate repair and replacement of damaged or de-
stroyed components. High value assemblies, such
Transportability
as the pump and power system, are required to
Transport of the dredge is a critical design fac-
be far away from the dredgehead to reduce dam-
tor. To avoid adverse environmental impact result-
age due to detonation. Spare parts and a complete
ing from channeling the Flats in the process of
spare unit were specified to reduce downtime in
moving the dredge between contaminated areas,
case of a catastrophic explosion.
the unit needs to be air transportable. The options
As mentioned previously, the power system
for transport by helicopter are the UH-1 (Huey),
was designed to minimize the effects of a UXO
the UH-60 Blackhawk, and the CH-47 Chinook.
detonation while dredging. The hydraulic system
Load capacity and operating cost per hour increase
uses a nontoxic, biodegradable fluid (Mobil EAL
with each model, while availability decreases. The
224H). System fluid loss will be limited due to a
load capacity of the Huey, at 680 kg, is too low for
pump shutdown circuit that senses the hydraulic
practical consideration. The Blackhawk had a ca-
reservoir level. To eliminate the possibility of con-
pacity of 3600 kg (upgraded to 4100 kg) and the
taminating the Flats with diesel fuel, the power
Chinook has a capacity of 5400 kg. Therefore, the
source for the dredge is located on shore and
specifications were written such that the dredge
power is supplied via electric cable.
should not weigh over 3600 kg unless a waiver is
granted by the Program Manager. In that case,
maximum weight is to be 5400 kg. Other features
Safety
The issue of ordnance brought up another im-
were specified to assist in movement and handling
portant design consideration: safety. The system
of the dredge.
was specified to be remotely controlled from an
Due to procurement difficulties, purchasing the
armored control cab. This cab, composed prima-
dredge equipment was not possible in the time
rily of 13-mm-thick welded steel and 31-mm-thick
frame available, so a lease contract for the equip-
ballistic polycarbonate (Lexan) windows, was
ment was pursued. The contracting office of the
blast tested in two separate tests using 105-mm
U.S. Army, Alaska (USARAK) was tasked with the
high-explosive (HE) rounds at a distance of about
responsibilities of writing, bidding and awarding
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