Journal of Energy Engineering

The reclamation and stabilization of uranium‐mill‐tailings sites requires engineering designs to protect against the disruption of tailings and the potential release of radioactive materials. The reclamation design is to be effective for 200‐1,000 years. This paper presents recently developed or refined techniques and methodologies used to evaluate uranium‐tailings‐reclamation plans designed to provide long‐term stability against failure modes. Specific cap‐design aspects presented include design flood selection, influence of fluvial geomorphology on site stabilization, stable slope prediction, slope stabilization using riprap, and riprap selection relative to rock quality and durability. Design relationships are presented for estimating flow through riprap, sizing riprap, and estimating riprap flow resistance for overtopping conditions. Guidelines for riprap‐layer thickness and gradation are presented. A riprap‐rating procedure for estimating rock quality and durability is also presented.

This paper outlines key items for reclamation of uranium tailings impoundments, using the reclamation of Exxon Coal and Minerals Company's (ECMC'S) Ray Point (or Felder) uranium mill site and tailings impoundment as a case history. ECMC's Ray Point is the first Title II site for which a final reclamation plan has been approved and constructed. Initial reclamation work of the Ray Point Site consists of mill decommissioning, mill site cleanup, and initial tailings impoundment cover placement. The licensing process in Texas consists of submitting the reclamation plan documents to Texas Department of Health (TDH), with subsequent discussion of the plans and submittal of additional data, analyses, and clarification. Following approval of the Ray Point reclamation plan, final reclamation work is carried out, and consists of random fill placement, compacted soil cover construction, topsoiling, and revegetation. The Ray Point site is currently monitored for specific performance criteria. After these performance criteria have been achieved, ownership of the property will be transferred to the state.

Two real‐life examples are presented to show how multicriterion decision‐making (MCDM) techniques can help hydropower engineers mitigate the environmental and social effects of hydropower development and operation. A brief introduction and overview of MCDM is presented, consisting of an 11‐step process that starts with problem definition and ends with implementation. A typology of MCDM is provided, dividing the techniques into three groups: outranking, distance‐based, and value‐ or utility‐based types. The operation of the Upper Isar River project in Bavaria is analyzed by means of a value technique and an outranking technique called multicriterion Q‐analysis. Fourteen criteria are considered in that study, including power production, habitat quality for four groups of species, aesthetics, several recreation indices, minimum flows, and phosphorus loadings. The case study of the Erlauf River Division in Austria is evaluated using a distance‐based technique, called composite programming, combined with Monte Carlo simulation. An outcome of that study is that the facility's owners have increased the minimum instream flow in order to protect ecological values.