Conclusions and Recommendations

Conclusions

and Recommendations

Conclusions

The flexible-discharge dustpan dredge demonstration project conducted in

the HOP area on the Mississippi River was successful. Because the Beachbuilder

demonstrated safe navigation and dredging operations, the objectives of the

project were met. USACE personnel, contractors, and bar pilots agreed that the

dredging operation was safe with respect to vessel traffic moving up and down

the river. The Beachbuilder dredged approximately 222,000 cu yd of sediment

and placed it in the designated marsh construction site. The majority of project

requirements were met, although the maximum pumping distance was 10,820 ft

with additional pipe available for the job; however, it was not required. Dredged

material was pumped the total distance using the ladder pump and only one of the

two deck pumps (5,400 hp out of a total available plant capacity of 9,000 hp).

Use of the second pump would have allowed the dredge to pump the required

distance of 15,000 ft. The flexible floating hose worked well with no leaks or

breaks.

Beachbuilder demonstrated the capability to cease dredging and move from

one side of the channel to the other in approximately 11 min when required. A

continuous dredging capability was demonstrated when the Beachbuilder was

operating in the RDB half of the channel. Single deep-draft vessel traffic could

safely pass in the LDB half of the channel when the Beachbuilder dropped its

cross-channel anchor wire and picked it back up after the vessel traffic cleared.

Forward movement into the cut was maintained by the push tug. Travel back into

the RDB side of the channel due to vessel traffic was conducted if dredging

operations were ongoing in the LDB half of the channel, two vessels passed each

other in the channel abreast of the dredging area, or if the river pilot in command

of the vessel requested additional clearance.

The average production rate for the entire 192-hr-long demonstration was

1,200 cu yd/hr or 27,800 cu yd/day to dredge 222,000 cu yd. The average

production rate of the dredge while advancing was 2,300 cu yd/hr, with a maxi-

mum rate achieved of 4,600 cu yd/hr. The dredge achieved an average speed of

74 ft/min to back down and reset for each cut, and had an average advance speed

of 2.1 ft/min.

Chapter 7

Conclusions and Recommendations