Figure 8. Relative disposal volumes as a function of time for bulk and separated, hydraulically placed material, and separated, mechanically dewatered material

ERDC TN-DOER-C27

July 2002

(1 + w f )[(1 - xm )MS

]

+ MFi ρti

(10)

(1 + wi )(MSi + M Fi )ρt f

where

wi and wf = water content, as a decimal

MSi = mass sand, in situ or initial

M Fi = mass fines, in situ or initial

ρti = total or wet density, in situ or initial

ρt f = total or wet density, final

An estimate of the disposal volume following processing can therefore be obtained based on the

hydrographic survey and projected dredging depths VTi , and the bulking factor derived by

measuring the initial and final water content, sand and fine mass, and wet density of representative

samples, thus:

VTf = b VTi

(11)

The net volume recovery is then

∆V = VTi - VTf

(12)

Conceptually, it is valuable to con-

sider potential volume reduction in

the context of the processes being

utilized. Depending upon the proc-

ess under consideration, this may be

a time-dependent value. For exam-

ple, hydraulically dredged and

placed materials require additional

disposal volume to provide ade-

quate freeboard and settling depth

for effective solids capture. The in-

itial disposal capacity required for

hydraulic placement will therefore

be much larger than for mechani-

cally dredged, or mechanically de- Figure 8. Relative disposal volumes as a function of time for bulk

watered, materials. Figure 8 illus-

and separated, hydraulically placed material, and

trates the time-dependent nature of

separated, mechanically dewatered material

volume recovery, which determines