species. The specific objective in 5 years is to
Identify potential remedial technologies.
reduce the mallard mortality rate by 50%
Assemble technologies into alternatives.
compared to the value in 1996. The objective
Technologies were identified that may be
in 20 years is to reduce that mortality rate to
no more than 1% above the reference value.
effective in reducing the impacts of the WP expo-
sure at ERF. This may occur by reducing the con-
Reduce hot zones. This RAO supplements the
centration of WP in the sediment or by reducing
RAO for duck mortality. The number of
the exposure of the receptors to WP. Fifteen
hectares characterized as "hot" will be used
potential technologies represented the range that
to measure achievement of this objective. In
was considered to be potentially feasible after
general, a hot zone will be determined by a
combination of duck mortality, WP concen-
many previous years of study and testing at ERF.
trations or quantity, duck usage, and crater
On the basis of information available from the
density. The specific objective is to reduce
treatability studies and vendors, the technologies
hot zones by 50% in 5 years and by 99% in 20
were screened on the criteria of effectiveness,
years compared to the number of hectares in
implementability, and cost. This screening result-
ed in 10 technologies being screened out and the
Reduce WP exposure pathways. This RAO will
following six retained:
be used as the basis for measuring the suc-
cess of remedial actions. It is technology-
Detailed monitoring of natural processes.
specific and designed to provide near-term
feedback on the success of a specific reme-
Pond draining by breaching.
dial action performed at a specific area. The
Pond draining by pumping.
specific objective is no bioavailable WP for
ducks and swans.
The technologies that passed through screen-
ing were assembled into five alternatives, which
Develop pond grouping
were assembled to meet several objectives. First,
The 22 hot ponds identified in the RI have been
the no action alternative was included as
divided into six groups. This was done to aid in
required by the NCP. Second, technologies were
the evaluation of alternatives for the FS and to
combined into action alternatives in such a way
allow for the selection of different remedies at dif-
that the alternatives would be complete; that is,
ferent pond groups based on the different charac-
each alternative would address the range of
teristics of each group. These pond groups are as
exposure pathways identified for WP.
The five assembled alternatives are as follows:
Northern A (seven ponds).
Alternative 1, no action. No remedial action
Pond 290 (one pond).
or monitoring is performed.
Pond 183 (one pond).
Alternative 2, detailed monitoring. No reme-
Pond 146 (one pond).
dial action is performed, but detailed moni-
Northern C and C/D Ponds (eight ponds).
toring is conducted to observe whether
Ponds 109, 285, 293, and 297 (four ponds).
natural processes that assist RAO success
The first five groups were made based on nearby
are occurring at the flats. Hazing is per-
types of vegetation, topography, knowledge of
formed as a temporary interim measure.
Alternative 3, pumping and AquaBlokTM.
Pumps are used to drain the pond groups so
similar physical characteristics and are expected to
that the drying sediment can allow the exist-
a respond similarly to remedial actions. These five
ing WP to sublimeoxidize and therefore
pond groups are separately evaluated in this FS.
decrease concentrations. After 5 years of
The sixth group of ponds either have had treat-
pond draining, AquaBlokTM is then spread
ment or will have treatment in 1997. Hence, these
over any remaining contaminated areas.
ponds will not be evaluated in this FS. They are in-
Detailed monitoring is included in this
cluded in the overall monitoring program for ERF.
alternative. Hazing is also conducted as a
temporary interim measure.
Development of remedial alternatives
Alternative 4, breaching, pumping, and
There were three steps in the development of
AquaBlokTM. Ditches are first created to drain
remedial alternatives for this FS:
the ponds via existing gullies or Eagle River.