Agnew Lake Uranium Mine
Assistance was provided to Agnew Lake Mines in the receipt of approval to allow the Atomic Energy Control Board (AECB) decommissioning license to lapse. SENES completed a pathways analysis for the site and coordinated and submitted the final monitoring summary report for the five year transition monitoring phase. SENES also provided testimony before a hearing with the AECB in support of Agnew Lakes application which was approved. Ownership of the property now resides with the Province of Ontario. (Kerr Addison Mines Limited)

Atlas Tailings Pile Reclamation
SENES undertook a comparative screening level risk assessment of the proposed on-site reclamation plan and an alternative off-site reclamation option for this 10.5 million ton uranium tailings pile situated near Moab, Utah. The project included review of planned activities and assessments of associated radiological and non-radiological risks to the environment, public, and reclamation workers along with a comparison to the "no action" base case. In NRC's EIS assessment, staff concurred with the results of the SENES risk analysis. In addition to the risk analysis, SENES performed a review of the NRC regulatory and decision making framework, a review of Title I and Title II reclamation precedents and costs, carried out probabilistic cost estimate sensitivity analyses, and assisted Atlas and national counsel in development and presentation of public information and in producing comprehensive responses to NRC's DEIS and DTER. (Atlas)

Beaverlodge Uranium Mine
An engineering feasibility study was undertaken by SENES to assess the engineering requirements and the environmental and cost implications of several potential reclamation concepts for the ultimate close-out of the Beaverlodge uranium mine/mill facility in northern Saskatchewan. Reclamation concepts were developed for each component of the mine/mill facility including the tailings areas, tailings spills, waste rock piles, mine water sludges, mines, mill and ancillary facilities. Detailed pathways analyses were subsequently undertaken for selected reclamation options. Site-specific radiation measures, an evaluation of eating habits specific to the area, and a literature search of critical pathways parameters (e.g. water to fish transfer factors) were used to estimate the potential radiation exposures resulting from several reclamation options. A water quality model was developed mainly to simulate uranium and radium-226 levels over an extended timeframe for input to the pathways analysis.

The mine was successfully decommissioned and reclaimed. The Province of Saskatchewan and Eldorado Resources (now Cameco) have jointly participated in monitoring the transition years. The facility has largely performed as expected and negotiations are ongoing for transfer of the property back to the Crown. (Eldorado Resources Limited)

Chemical Reaction Modelling in Reactive Tailings
The primary objective of this work was to provide a model for predicting the long-term potential of acid generation in sulphidic tailings and for evaluating the effects on acid generation of alternative closeout concepts. The initial version of the model framework, known as the Reactive Acid Tailings Assessment Program (RATAP), was developed over the course of several projects under contract to the Canada Centre for Mineral and Energy Technology. The initial version of the model was designed to predict, on a long-term basis, the rate and the extent of acid generation and concomitant major geochemical events brought about by the chemical and microbial oxidation of pyrite in uranium tailings. This model was subsequently adapted to base metal tailings (RATAP.BMT) by including other sulphide ores such as arsenopyrite, galena, pyrrhotite and sphalerite. It consists of eight modules: initial inventory, soil temperature, oxidation kinetics, oxygen transport, sulphide oxidation, solute transport, aqueous speciation, and trace metal chemistry. The program can be run in a probabilistic or a deterministic manner. The original version of the model (RATAP) has been calibrated and validated extensively on pyritic uranium tailings. Partial validation of the modified computer model (RATAP. BMT) has been performed using field study data on the high sulphide tailings at Waite-Amulet in northeastern Quebec, some relevant data from pyritic uranium tailings investigations in the Elliot Lake area of northern Ontario, and laboratory observations. (Energy, Mines and Resources Canada; now Natural Resources Canada)

Collins Bay Uranium Mine
To assess the impact of a waste rock pile and open pit, laboratory scale leaching studies were designed and evaluated to determine the acid generation potential and the leachability of metals and radionuclides from the mine wastes. The project involved the development of a water quality model to assess reclamation strategies for the B Zone open pit and waste rock pile developed adjacent to Collins Bay on Wollaston Lake. The model simulated metal and radionuclide leaching from waste rock, mineralized waste and exposed ore and evaluated the potential benefits of reclamation alternatives. Pathways analyses to estimate the radiation exposure of local residents in the Wollaston Lake area of northern Saskatchewan were also prepared. (Cameco Corporation)

Denison Uranium Mine
SENES was a member of a team which developed and finalized the closure plan for the Denison mine/mill facilities and waste management area at Elliot Lake in northern Ontario. SENES' role is to complete all environmental components of the study, address acid generation controls and determine long-term environmental impacts, including modelling of the long-term dose to local inhabitants. The project also entailed the assessment of environmental and human health risks of accidental events and failures. (Denison Mines Limited)

Germany Uranium Mines
The re-unification of east and west Germany has provided an unparalleled challenge related to the publicly acceptable and cost effective environmental decommissioning of the former East German uranium mining and processing industry.

Since 1991 SENES has been advising the West German Federal and State Ministry's of the Environment on the complex environmental and scientific needs associated with decommissioning and rehabilitating lands and surrounding areas affected by the former East German uranium industry.

The decommissioning challenges related to this program are equal to or greater than any such task previously faced by the western mining industry. Key issues that need to be addressed include, among many:

• rehabilitation of more than 500 million m3 of waste rock;
• restoration of background natural waters which have been altered by more than 40 years of mining;
• cleanup and release of more than 8,800 acres of surface lands;
• stabilization and decommissioning of large scale settling basins containing chemical and radioactive contaminants.

In addition to the scientific and engineering needs, all of the above works must be addressed in a cost effective and timely manner within the complex infrastructure resulting from reunification of the two Germany's. Additionally, the work is complicated through the close proximity of large populations that will be affected by all actions.

Based on our recognized leadership in the area of radiological and environmental sciences, and a proven record of practical and effective application of these sciences and management practices, SENES Consultants Limited has played a key role in the assessment of the above issues and the development of strategies addressing the need for a long term integrated decommissioning plan that will meet with government and public acceptance. (Germany Environment Ministry)

Lacnor, Nordic, Pronto and Spanish American Uranium Mines
SENES completed an overview of closure options and costs for five inactive sites currently under long term care and maintenance in the Elliot Lake area of northern Ontario. The principal concerns at these properties pertained to long-term acid production from the sulphidic tailings and the ongoing operation of effluent treatment plants. (Rio Algom Limited)

Quirke and Panel Uranium Mines
SENES has participated in several investigations over the years aimed at the development of decommissioning plans for the Quirke and Panel uranium mines, mills, and associated waste management areas located in the Elliot Lake region of northern Ontario. This work has progressed through a review of options, preparation of an environmental and radiological pathways analysis, presentation of the decommissioning proposals to the Atomic Energy Control Board (AECB) and preparation of six environmental screening reports for submission to the AECB in accordance with the EARP process. All decommissioning activities and their attendant environmental impacts were identified; specific ameliorative and mitigative actions were recommended as required.

The decommissioning plan proposed for the Quirke tailings area involved the construction of an elaborate dam and dyke system to facilitate the flooding of the tailings management area, the institution of an interim mine dewatering program, and the implementation of radiological protection and decontamination methodologies. At Panel, the closure plan recommended for the tailings area entailed raising the perimeter dams to flood the tailings and thus control acid production and long-term contaminant migration of the receiving environment. (Rio Algom Limited)

Rabbit Lake Uranium Mine, Saskatchewan
SENES recently conducted a field program at the Rabbit Lake minesite followed by a laboratory program in order to characterize waste rock and mineralized waste, and to monitor the leachability of these materials. The program involved rock sampling, which included documentation of sample characteristics, field paste pH and conductivity measurements, and seepage water sampling. The laboratory program involved geochemical analyses and static tests (acid base accounting) followed by dynamic testwork (humidity cells and saturated columns) as well as leach tests and buffering tests. The interpretation of the results included evaluation of acid generation and leaching potential. The information from this assessment was subsequently used in geochemical modeling of the waste rock piles and in an environmental pathways analysis. (Cameco Corporation)

Stanleigh Uranium Mine
SENES prepared a conceptual closure plan in 1990 for the Stanleigh mine and mill facilities and waste management area. The closure plan was required as a condition of the Atomic Energy Control Board regulatory guide. The plan is presently under revision and being updated to reflect current developments from Rio Algom's Quirke and Panel closure plan studies. (Rio Algom Limited)

Stanrock Waste Management Area
The tailings in the Stanrock Waste Management Area (WMA) at Elliot Lake, Ontario, pose the usual acid mine drainage (AMD) problems associated with sulphidic mine wastes. Treatment of runoff and seepage from the WMA has been practised for two decades for neutralization of acidity, precipitation of heavy metals and removal of radionuclides. Faced with the prospect of continuing to treat the AMD for tens of years into the future, an investigation was undertaken to assess the costs and benefits of moving the tailings to a new facility or constructing new impermeable structures around the existing WMA, versus leaving the tailings in place and continuing to treat the AMD and handle the chemical sludge produced during treatment. The long-term acid generation potential of the tailings was modelled to assess how long into the future acid will continue to be produced from oxidation of the iron sulphide minerals. The investigation showed that the costs associated with all potentially viable options were high, although the benefits varied widely. (Denison Mines Limited)

Uranium Tailings Assessment Program Development
SENES developed, under contracts to the National Uranium Tailings Program administered by CANMET, Energy Mines and Resources Canada, a probabilistic computer model for predicting the long-term effects of sulphidic uranium mill tailings close-out options. The project involved: evaluation of three potential computer codes for carrying out a probabilistic assessment; delineation of the principal characteristics of a typical reference tailings site; selection of key pathways of radionuclide exposure of reference receptors; development of source term, environmental compartment, transfer, and dose models; assessment of the probability distributions and main attributes of the input parameters; evaluation of sensitivity and uncertainty analysis techniques for application to the output results; and execution of preliminary probabilistic assessments for selected tailings close-out options. The principal focus of the project was on the development of a flexible but user-friendly probabilistic assessment code. In addition to the concepts outlined above, the Uranium Tailings Assessment Program (UTAP) handles time dependency, spatial dependency, variable site characteristics, and numerous radioactive and non-radioactive contaminants. (Energy Mines and Resources Canada)