Incorporating Color Change Propensity into Dredged Material Management to Increase Beneficial Use Opportunities

Abstract

Dredged materials provide a number of beneficial use opportunities, including beach nourishment, habitat creation and restoration, and other activities. In situ sediment color is important for determining aesthetic and habitat suitability, for beach nourishment, and for other projects. However, dredged materials must meet locally established color compatibility requirements (for example, material cannot be too dark). Often, potential sediment sources are close to meeting specified color thresholds, and previous observations suggest that sediments lighten over time. In response to these observations, this study quantified sediment color change potential in a dredged m aterial management context. Results indicate that dredged material sediment color responded to changes in secondary color components, sediment mixing, and photolytic bleaching improving the sediment color for beneficial use application. Findings allowed for development of a conceptual color change capacity framework and supported development of tools for resource managers to incorporate color change dynamic into planning and operations activities.The following report provides a framework for determining the color change capacity of dredged materials using (1) a comprehensive laboratory approach and (2) a semiquantitative index based on source material and placement location conditions. These tools allow practitioners to incorporate dredged-material color change into resource management decisions, thus increasing beneficial use opportunities.