SUMMARY AND DISCUSSION

ERDC TN-DOER-I4

August 2000

Table 1

need title

Description

SI Measured

Thompson Daily Report

Percent Difference

Effective Time1

81.0 hours

81.35 hours

0.43

Distance advance on 10/1/1999

285.59 m (937 ft)

286.51 m (940 ft)

0.32

Cu m (cu yd)/hr

831.83 cu m

831.82 cu m (1088 cu yd)

7.3

(1008 cu yd)2

Over entire reporting interval.

Using an in situ density of 1.9 cu cm over entire reporting interval.

SUMMARY AND DISCUSSION: Good daily documentation of a dredging project is essential.

The SI can help document the position and production state of the dredge. However, some aspects

of the project, such as pipeline length and terminal elevation are best entered manually. The SI

facilitates daily reporting by producing daily reports based on recorded data and allowing the

electronic filing of existing standard dredging forms (such as Engineering Form 4267). Each Ship

Server serves as an Internet gateway, which allows the transfer of these reports to the shore-based

SI via standard internet protocols.

Using the actual performance data provided by the Thompson's DSS, the SI can produce some of

the numbers as shown in Table 1, commonly used by dredging inspectors and managers. Although

dredge surveys provide the final evaluation of dredge production, the SI can provide production

estimates between surveys to help identify potential problems earlier. Also, the detailed production

data from the HPDSI can help to assure that the contractor is operating the dredge in the manner

consistent with District wishes. For example, it may be desirable to maximize the solids concen-

tration of the dredge discharge to reduce the amount of effluent from a confined disposal facility.

The positioning data provide insight to dredging contract administrators and estimators. These data

help confirm estimates of dredge swing rate and width. Although it is usually not in the interest of

the contractor to perform any dredging work outside of the dredge prism, and contractors now have

the tools to accurately position themselves, it is still necessary to assure that the contractor is working

only in designated areas. Overdredging is undesirable especially for jobs where the cost to dispose

of the material is high. The HPDSI provides tools to allow inspectors to review the dredge data

back in the office or on the dredge independent of the DSS software (if the DSS software supports

this playback capability if it can be used as well). Additionally, the detailed SI data can be used to

directly compute the swing and cycle efficiency, which are useful to dredge estimators to compute

the theoretical production capability of the dredge.

The SI provides a means to manage historical data as well. The SI database can contain the daily

reports, raw and computed data, and project and contract tracking information. The SI database

forms the backbone of the Ship Server and shore-based systems. Future technical notes will cover

these capabilities and more advanced and in-depth dredge data analysis, including additional

examples from the HPDSI on the Thompson.