Guide for a Risk-Based Approach to Environmental Windows for Dredging and Navigation Infrastructure

PIANC EnviCom Working Group 227 is developing a decision-making guide associated with the application of environmental windows for dredging and marine navigation infrastructure construction. Dredging and construction works are often restricted during certain periods to reduce potential impacts on environmental receptors. Times when the potential environmental impacts of the project are thought or perceived to be unacceptable—and, consequently, works are not allowed—are commonly defined as seasonal restrictions. Conversely, environmental windows are the periods when works are allowed. Limiting projects to fixed environmental windows complicates contracting schedules by constricting them, adds challenges with respect to the availability of construction equipment, and extends project timelines. These limitations can also impact the safety of works and inflate their cost. The objective of this guide is to provide a risk-based decision-making process that can be applied in cases where restrictions on dredging and navigation infrastructure work may be considered. Case studies are included.