Final Site Information Package for National Remedy Review Board ...
Final Site Information Package for National Remedy Review Board ...
Final Site Information Package for National Remedy Review Board ...
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SITE INFORMATION PACKAGE FOR NATIONAL REMEDY REVIEW BOARD<br />
PART B, SECTION 9: COMPARATIVE ANALYSIS OF ALTERNATIVES<br />
estimated effectiveness at completion of remedial actions is also slightly higher <strong>for</strong><br />
Alternative 4+ than <strong>for</strong> Alternative 3+. The differences in ranking among the OU 2<br />
alternatives under this criterion do not outweigh the differences between Alternatives 3+<br />
and 4+. The ranking of the OU 2 alternatives under this criterion, from highest to lowest, is<br />
as follows: e, d, c, a, and b. This ranking is based on the relative differences in post-remedial<br />
dissolved zinc loads in the SFCDR, immediately following the implementation of remedial<br />
actions.<br />
9.1.4 Reduction of Toxicity, Mobility, or Volume through Treatment<br />
All the remedial alternatives are considered to satisfy the statutory preference <strong>for</strong> treatment,<br />
and the treated water flow rates are relatively similar <strong>for</strong> all the alternatives. OU 2<br />
Alternatives (a) and (b) do not include treatment and, there<strong>for</strong>e, rank lower under this<br />
criterion. Alternative 4+ ranks higher than Alternative 3+ because, although the estimated<br />
flow rate <strong>for</strong> treatment at the CTP is very similar, a significantly higher number of adit<br />
discharges would be treated under Alternative 4+. The statutory preference <strong>for</strong> treatment is<br />
satisfied through reduction of total volume of contaminated media—in this case, surface<br />
water. The water treatment technologies to be employed would separate the metals from the<br />
water. These metals would then require disposal in repositories. For each of the remedial<br />
alternatives except <strong>for</strong> No Action, Tables B9-1a and B-91b present an estimate of the total<br />
dissolved zinc load removed from the water through treatment (and there<strong>for</strong>e a reduction in<br />
the zinc loading to the surface water). The estimates in Table B9-1a range from 700 pounds<br />
per day (lb/day) <strong>for</strong> Alternative 3+(a) to 1,880 lb/day <strong>for</strong> Alternative 3+(d); the estimates in<br />
Table B9-1b range from 600 lb/day <strong>for</strong> Alternative 4+(a) to 1,760 lb/day <strong>for</strong><br />
Alternative 4+(d).<br />
9.1.5 Short-Term Effectiveness<br />
All of the alternatives based on Alternative 3+ rank higher under the criterion of short-term<br />
effectiveness than those based on Alternative 4+ because Alternative 4+ would pose much<br />
greater short-term negative impacts during construction than Alternative 3+, regardless of<br />
which OU 2 alternative it is coupled with. This is primarily due to the extensive nature of<br />
the remedial actions that would be conducted under Alternative 4+, which would require a<br />
much longer time period to complete (decades longer); the similar water quality expected to<br />
be achieved after the implementation of remedial actions; and the similar time frame needed<br />
<strong>for</strong> natural source depletion to further improve water quality and achieve ARARs. The<br />
ranking of the OU 2 alternatives from highest to lowest short-term effectiveness is as<br />
follows: d, c, b, a, and e. This ranking is based on a balance of implementation time,<br />
effectiveness, and short-term risks.<br />
9.1.6 Implementability<br />
All of the alternatives based on Alternative 3+ rank higher under the criterion of<br />
implementability than those based on Alternative 4+, because Alternative 4+ would have<br />
substantially increased technical and administrative feasibility considerations compared to<br />
Alternative 3+. Alternative 4+ has generally the same types of implementability<br />
considerations as Alternative 3+, but with much larger quantities and larger repository<br />
requirements. The ranking of the OU 2 alternatives from most to least desirable on the basis<br />
of implementability is as follows: c, d, b, a, and e.<br />
B9-4