Recommendations - trchl04-30057

For this particular demonstration and location, a flexible-discharge dustpan

dredge proved most efficient at the HOP working on the RDB side of the channel

(inside of the bend) where shoaling tends to be greater and the dredge can operate

almost continuously while allowing passage of most deep-draft vessels. Working

the RDB side also removes the dredge from the potential hazard of a passing

vessel losing power and drifting toward the LDB side (and dredge) by current

flow into Pass A Loutre.

With use of just one hard point/discharge pipeline, the dredging of numerous

spot shoals separated by relatively long distances (distances that would require

the discharge line to be relocated numerous times) would be more efficiently

accomplished using hopper dredges (the use of multiple hard points/discharge

lines was not investigated during the demonstration). The safety aspects and

operational characteristics determined by this demonstration will provide infor-

mation necessary to determine if a flexible-discharge dustpan dredge will be

feasible for use in other specific reaches of the Mississippi River and in other

navigation types of dredging projects (with free-flowing, relatively noncohesive

material) such as construction and maintenance of sediment traps.

Relevant operational characteristics of the Beachbuilder determined from the

demonstration project were compared to corresponding criteria in the 1998 publi-

cation "Assessment of Coastwide Louisiana Maintenance Dredging Capabilities

under the Federal Standard." The demonstration provided experience in the use

of a flexible-discharge dustpan dredge. Although the utility of this type of dredge

in pumping 15,000 ft was not directly proven, the dredge could have achieved

this pumping distance as per the conclusions previously presented. Mobility-

related operational characteristics from this demonstration will provide informa-

tion necessary to evaluate dredge mobility in working between specific dredging

assignments and in sailing between specific dredging regions. The Beachbuilder

demonstrated the capability to conduct shore placement of dredged material in a

relatively long pumping distance mode. The minimum-acceptable dredging rate

of 24,000 cu yd/day in the assessment criteria was achieved by the Beachbuilder

(27,768 cu yd/day) given the demonstration conditions previously discussed.

These demonstration results identified a flexible-discharge dustpan dredge's

capability for safely yielding to vessel passage, but, due to the fact that the entire

project was conducted at the HOP, the dredge's capability in challenging sea

conditions was not demonstrated.

Recommendations

Areas were identified where changes could improve the efficiency of the

flexible-discharge dustpan dredge operation. These recommendations include

both operational as well as equipment-related aspects for future flexible-

discharge dustpan operations at the HOP or in other regions and applications.

The use of a contract Mississippi River Bar Pilot onboard the dredge helped

ensure the government of achieving its mission to maintain safe navigation. The

pilot assisted in vessel traffic coordination and allowed the leverman to concen-

trate more fully on maximizing dredge production (with no in-hull propulsion,

Chapter 7

Conclusions and Recommendations