Appendix D: Short-Term Fate (STFATE) of Dredged Material Model

Appendix D

Short-Term Fate (STFATE) of

Dredged Material Model

Introduction

This appendix presents a summary description of the STFATE (Short-Term

FATE of dredged material disposal in open water) model, a module of the

Automated Dredging and Disposal Alternatives Management System

(ADDAMS) (Schroeder and Palermo 1990). ADDAMS is an interactive

computer-based design and analysis system in the field of dredged-material

management. The general goal of the ADDAMS is to provide state-of-the-art

computer-based tools that will increase the accuracy, reliability, and cost

effectiveness of dredged-material management activities in a timely manner.

The description of STFATE given in this appendix is a summary of the detailed

information available in the users guide for the model provided in the inland

testing manual for dredged material disposal (U.S. Environmental Protection

Agency/U.S. Army Corps of Engineers (EPA/USACE), in preparation).

Theoretical Basis

The STFATE module is based on the earlier DIFID (DIsposal From an

Instantaneous Discharge) model originally prepared by Koh and Chang (1973).

STFATE has been refined several times to expand its predictive capability over a

wider range of project conditions. The model is used for discrete discharges

from barges and hoppers. The behavior of the material during disposal is

assumed to be separated into three phases: convective descent, during which the

disposal cloud falls under the influence of gravity and its initial momentum

imparted by gravity; dynamic collapse, occurring when the descending cloud

either impacts the bottom or arrives at a level of neutral buoyancy where descent

is retarded and horizontal spreading dominates; and passive transport-dispersion,

commencing when the material transport and spreading are determined more by

ambient currents and turbulence than by the dynamics of the disposal operation.

Figure D1 illustrates these phases. Details on the theoretical basis of the model

are found in EPA/USACE (1991), EPA/USACE (in preparation), Johnson

(1990), Koh and Chang (1973), and Brandsma and Divoky (1976).

Appendix D Short-Term Fate of Dredged Material Model