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Bucket Loading Characteristics
The water-to-solids volume (loading) ratios of the buckets were calculated to be, respectively,
3.75 for the CableArm, 3.97 for the Enclosed bucket, and 3.76 for the Conventional
bucket.
Near Field
Based on turbidity measurements, the Conventional bucket produced the highest amount of
sediment resuspension spread throughout the water column. Use of the CableArm bucket
appeared to reduce sediment resuspension in the water column as the observed depth-averaged
turbidity was 46 percent less than observed for the Conventional bucket; insufficient TSS data were
collected during the CableArm bucket operation to completely confirm this reduction, although
the few data collected show an even higher reduction. The Enclosed bucket had the lowest
overall turbidity and substantially less in the middle of the water column. Observed
depth-averaged turbidity for the Enclosed bucket was 79 percent less than observed for the
Conventional
bucket. This compared well with observed TSS which showed depth-averaged TSS
concentrations for the Enclosed bucket 76 percent less than for the Conventional bucket.
Far Field
The BBADCP provided good qualitative data to indicate relative amounts of sediment
resuspension in the plume and delineate its boundaries. BBADCP data results correspond to
results from those data collected in the near field. BBADCP coverage provided insight on
where to sample with more the quantitative sampling equipment of the BOSS. Regrettably, an
error in the BOSS data acquisition software resulted in profile measurements achieving a
maximum depth of only 69 percent of that intended (and displayed in real-time aboard the survey
vessel). Consequently, no data were acquired in the lower 30-40 percent of the water column during
either the vertical profiling or horizontal towing on any of the three days of monitoring
operations. This error limited coverage of BOSS-collected data, but these data are still being
analyzed with regard to calculation of mass (i.e., the load of suspended solids per unit of
receiving volume during dredging operations). The results of this analysis will be published in
a report currently in preparation.
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