Database of detailed costs of dam removals

Dam removal is an important management tool for addressing aging infrastructure, public and structural safety, restoration of river connectivity for migratory organisms and recreation, and habitat quality. However, planning for dam removals is constrained by the difficulty of cost estimation. To our knowledge, published data on dam removal plans, total costs, and the cost drivers does not currently exist. The lack of information limits the ability of practitioners to consider dam removal as an alternative to addressing infrastructure issues. To address this deficiency and to identify which factors drive the costs of dam removals, we compiled a detailed cost database as a collection of 15 case studies with detailed removal costs and features of the dams. Detailed costs were extracted from bid abstracts and/or schedule of values, and dam features (e.g. stored sediment volume, composition, and contamination, dam removal strategy, streamlining of permitting, mitigation measures) were based on interviews with project managers. The data set illustrates how and why dam size (e.g., height) only roughly predicts cost of removal. The data indicate that sediment volume and management strategy better predicted removal cost than dam height. Other cost drivers appear to be restoration activities (e.g. revegetation, fish passage, stabilization), construction approaches (e.g. dewatering, construction of channel features) and mitigation measures (e.g. water supply, pumping plants). Finally, unique features of individual projects contributed to higher costs, including litigation, stakeholder engagement, or mitigation projects. The databases will be publicly available and are being used in the development of order-of-magnitude cost estimation tools.