Performance Goals and Objectives

ERDC TN-DOER-T7

October 2004

into account the risk tolerance of all parties in order to achieve project goals and minimize costs

as well as establishing the basis for contract payment.

Performance Goals and Objectives. Processing goals and objectives must be clearly

articulated and the manner in which performance will be evaluated explicitly specified. A

careful cost/benefit analysis will help to identify the chief operating objectives. For example, in

cases where volume and weight of material must be minimized in order to reduce transportation

and offsite disposal costs, the performance specification might be based on a minimum cake

density and maximum water content that would be acceptable. However, a processing cost

incurred to achieve a tight specification may offset the potential savings in transportation and

disposal costs. A slightly less efficient and less expensive treatment train might yield the lowest

overall project costs.

Risk Tolerance. Performance specifications written with a tight material specification

increase the risk to the contractor, who must base his ability to process a heterogeneous material

to specifications on limited bench and pilot testing. Higher risk generally results in higher

contract bids. Conversely, a contract specifying only the processing method, which might be

considered desirable based on results of preliminary bench scale testing, would be easier for the

contractor to estimate, but may not sufficiently motivate the contractor to operate in a manner

that optimizes material properties or results in the least cost for the sponsor.

Processing interruptions in the dewatering circuit may impact the dredging operation. Because

both dredging and dewatering are relatively specialized functions, however, contracts may be let

to separate companies who may then find themselves in an adversarial position. The dewatering

plant must have adequate capacity to minimize disruptions to the dredging. Similarly, the dredge

must be operated in a manner that provides the greatest possible uniformity in the influent to the

dewatering circuit. Highly variable slurry solids or flow rates may result in processing upsets

and down time on both ends. Instrumentation linking the dredging plant and the dewatering

circuit can minimize problems and reduce overall costs due to greater operating efficiency. This

approach has been demonstrated in the field and is described in the Clinton, Iowa, fact sheet in

Appendix A.

Material Properties. Performance specifications based upon material properties must

consider the possibility of material variability on both sides of the treatment train and specify

remedies and responsibilities arising from that. Off-spec materials may result from processing

operations that are not sufficiently robust or from poor process design. However, off-spec

materials may also result from unanticipated variability in the feed. If the material obtained for

bench-scale testing and process design is not representative of the full range of materials to be

processed, substantial additional costs may be incurred in order to make necessary modifications

to the process.

Plant design is based on the measurable properties of representative samples, taking into account

an appropriate level of variability and uncertainty. This could be taken to constitute a feed

"spec." The processing modifications required to handle feed outside these parameters should be

anticipated, however, and costed along with the mainstream processing activities. For example,

if sand content was less than 2 percent in the pre-design sampling, and no sand removal