Planning Level Cost-Benefit Analysis for Physical Separation at Confined Disposal Facilities

ERDC TN-DOER-C27

July 2002

Planning Level Cost-Benefit

Analysis for Physical Separation

at Confined Disposal Facilities

PURPOSE: This technical note is the fourth in a series providing guidance on evaluating the

potential for recovery of dredged material from confined disposal facilities (CDFs) for beneficial

use (BU). Olin-Estes and Palermo (2000a, 2000b) and Olin-Estes (2000) discuss physical separa-

tion concepts as they apply to dredged material recovery, mathematical relationships for estimating

recoverable material, and methods for developing sampling plans for CDFs to support these

evaluations. This technical note describes a conceptual approach to estimating the comparative cost

benefit for separation as a volume reduction method, based on recoverable volume, processing cost,

and disposal facility life and replacement cost.

BACKGROUND: The technical feasibility of separation as a management approach is dependent

upon several factors, including the ability to identify and separate distinct fractions within the

material that meet BU criteria. The economic feasibility of separation is dependent on the

complexity of the separation treatment train, disposal and BU alternatives and costs, site-specific

logistical considerations, and project scale.

The principal motivation for BU recovery of dredged material is the growing shortage of storage

capacity in CDFs, coupled with the high cost to replace this capacity. The fundamental purpose of

these technical notes is to assist in determining when material recovery is technically and economi-

cally feasible. Olin-Estes and Palermo (2000a, 2000b) and Olin-Estes (2000) provide strategies for

obtaining and interpreting physical and chemical information necessary for this evaluation at the

least possible cost. This technical note develops an approach for screening-level economic analysis

of separation alternatives, together with methods for quantifying potential volume reduction for

different processes, which can be used in planning-level decision making and in support of a detailed

cost-benefit analysis. It presents the basic economic principles and approach utilized, followed by

simple separation concepts and volume reduction calculations. Examples are developed for

one-time and long-term dredging projects to illustrate the relative importance of the different

variables involved.

INTRODUCTION: Although physical separation has been successfully demonstrated technically,

the economic viability of full-scale implementation is difficult to determine based on overall project

volumes and unit costs reported in the literature. Part of the difficulty can be attributed to the fact

that costs associated with small volume demonstrations are typically high on a per-unit basis. In

part, this is because mobilization and demobilization costs are relatively insensitive to the volume

being processed: a larger project will distribute these costs over a larger volume, resulting in lower

unit costs. For the most part, representative full-scale costs are difficult to extract from the literature

or from other projects because they are heavily influenced by site-specific factors such as local labor

cost, equipment availability, site accessibility, distance to water, terrain, weather and climate,

material characteristics, disposal requirements and costs, and differences in what is included in