Average production rates

of 5.51 hr on the first 2 days of the demonstration was (after accounting for the

over-reporting gross volumes reported in Form 4267) estimated to be

14,000 cu yd.

The nuclear density meter and flow meter were not calibrated for the site-

specific conditions at HOP. In order to adjust the (production meter) totalized

volume calculated with the time-series data, the (placement area survey volume

plus 20 percent fines) gross volume of 222,000 cu yd was reduced by

14,000 cu yd to approximately 208,000 cu yd and the 10-sec cubic-yards-per-

hour (production meter) readings adjusted accordingly so the totalized time-

series-calculated production volume equaled 208,000 cu yd as shown in Table 5.

The adjusted production values per advance are also listed in Table 5. The

production rate per advance was calculated by dividing the volume dredged per

advance by the total advance time. The highest production rate obtained during

the demonstration was 4,600 cu yd/hr while advancing 719 ft, and the average

production rate from all the advances in Table 5 was approximately

2,300 cu yd/hr.

During the demonstration, the ladder pump and only one of the two hull

pumps were used to pump slurry the required distances. Because the two hull

pumps were connected in series, the unpowered pump introduced significant

head losses into the hydraulic circuit, and the dredge's production numbers were

influenced by this operating condition.

Average production rates

The average production rate of the entire demonstration between the begin-

ning and end of dredging (192 hr) to move 222,000 cu yd was approximately

1,200 cu yd/hr or approximately 28,000 cu yd/day. The average production rate

per each reach (with delays incorporated) was calculated by totalizing the (time-

series-calculated) volumes and dividing by the total time spent at each reach. The

Beachbuilder spent a total of 17.75 hr (between start and stop of dredging) at

Reach 1 dredging approximately 16,500 cu/yd (14,000 cu yd estimated from

Form 4267 plus 2,500 cu yd calculated from time-series data) for an average pro-

duction rate of 931 cu yd/hr. A total of 128.5 hr was spent at Reach 2 dredging

approximately 206,000 cu yd for an average production rate of 1,600 cu yd/hr (or

approximately 38,400 cu yd/day). The average production rate per pumping hour

was approximately 2,300 cu yd/hr.

Factors affecting high and low range of average production rates

Estimates of high and low production rates that the Beachbuilder could

achieve while working in the two halves of the channel (LDB and RDB sides)

pumping the same distance as the demonstration (10,820 ft) are presented. These

estimates are based on the assumption that the dredge remains at one reach (does

not include relocating the hard point). The impact on pumping time by relocating

the hard point is further discussed in Chapter 6. As described above, the dredge

can work almost completely uninterrupted in the RDB side of the channel. On the

last day of the demonstration (13 June) Beachbuilder worked the RDB side to

Chapter 4

Dredging Operational Characteristics Analyses