Books can be ordered at:
A.A. Balkema Publishers
P.O. Box 1675
3000 BR Rotterdam
Ther Netherlands
Telephone: +31 10 414 5822
Fax: +31 1- 413 5947
E-mail: orders@swets.nl
Website: www.balkema.nl

1 INTRODUCTION

Analysis of how environmental concerns affect mining reveals a number issues; some of these issues form pairs that are somewhat mutually exclusive whereas other issues span across the whole subject. Cost is an issue that drives all decisions concerning mining and the environment, whereas the question of whether to concentrate efforts on active or abandoned operations can be considered as a somewhat mutually exclusive choice. In any environmental project, there are political, social, scientific, and engineering issues that will have to be considered in the final action plan. Also, there is the question of whether environmental problems brought about by mining are regional, national, or international issues. Finally, the question of whether the major environmental problems concern the atmosphere, water, or the earth is an issue when limited funds are applied to a major problem.

Because we have been awarded funding by the U.S. Environmental Protection Agency (EPA) for a major research Center that concentrates on mining and the environment, i.e., the Rocky Mountain Regional Hazardous Substances Research Center (RMRHSRC), we have had to assess these issues and decide which ones will control the research and outreach activities of the Center. Certainly, our decisions on which areas of this topic of mining and the environment deserve our concentrated efforts can be modified or changed; however, at this time it is necessary to make decisions so that our projects have an appropriate focus. In the case of the outreach and community service efforts of the Center, all hazardous substances will be addressed. However, the EPA specifically requested that this Center, located in Region 8 of the 10 national EPA regions, concentrate on the environmental issues related to mining wastes. This paper presents these issues and gives our beginning opinions on how they impact on the goals and operation of this new Hazardous Substances Research Center.

2 THE ISSUES

Cost is a dominant issue particularly because of the physical size of some mining wastes. Because many of the sites that have been impacted by organic wastes are U. S. Department of Defense and Department of Energy sites, development of innovative and low cost methods of treatment at these sites has been supported by significant Federal funding initiatives. However, the Federal government is not involved in any of the priority pollutant sites found in Colorado, Utah, Montana, Wyoming, South Dakota, and North Dakota, the states that make up Region 8. So, state and local governments are going to be required to some extent to initiate treatment efforts, and these entities demand a lowcost solution. Also, the record so far shows that high costs paralyze most current attempts at remediation. Consequently, cost limits both the scientific questions that can be answered with respect to a given problem as well as the level of technology that can be implemented to solve the problem.

Although this is a regional center, treatment of environmental problems related to mining is obviously a global issue. Also, some academic, governmental, and private agencies beyond this region and nation have a great track record on working on the treatment of mining wastes. The MEND Program of Canada and the Acid Drainage Technology Institute of the University of West Virginia are two examples. Also, political restrictions, such as the good Samaritan problem within Colorado, sometimes create hurdles that must be overcome when attempting pilotscale and fullscale treatment projects within the region. Consequently, in preparing our proposal and now in carrying out the objectives of the Rocky Mountain Regional HSRC, our approach will be global. At least two of the four research projects have investigators outside of the region. The EPA dictates that outreach activities be coordinated across the EPA Regions. However, for the technology transfer and outreach of this Center to be successful, the Center also must work with other entities outside of Colorado and Region 8 that have already been concentrating on the treatment of mining wastes.
In the case of mining wastes, social and political issues will eventually drive most treatment efforts. However, this Center will concentrate on the scientific and engineering aspects of the problem. The objective will be to make the answers to all the scientific and engineering questions to be clear and complete enough that the social and political issues can be played out on a welldefined scientific and engineering field.

With respect to concentrating on active versus abandoned mining operations, the plan will be to start studies on abandoned operations and then to convince the mining industry that solutions developed through the research activities can be transferred to active operations. Since the Summitville disaster of December 1992, the permitting procedures for all states appear to be so extensive that all contingencies are taken into consideration. In particular, a complete closure plan has to be included in any new mining permit, and companies understand that their liability extends through the closure of the operation. Currently, opening and operating a mine depends on environmental regulations that are based on reasonably good science and engineering. Thus, the Center will begin operations concentrating on abandoned mining lands (AMLs). There also are some issues related to current operations that certainly deserve study, such as whether the models used to predict pit water chemistry are accurate, and how to bring a continuing operation that was started in the 1970's or 80's into compliance with the current regulations that relate to new operations. However, AMLs comprise the majority of the problems in Region 8 and appear to be a more fruitful area for the application of science and engineering for developing inexpensive and innovative treatment strategies. Also, bringing a current operation into compliance with more modern regulations means that treatment is done after contamination has occurred. Consequently, this can be considered to be similar to the treatment of an abandoned operation.

When considering whether the most important problem is contamination of the air, water, or earth, the water and the earth command the most attention. The question of what to do with abandoned tailings and waste rock piles represents the largest physical problem in any of the national priority pollutant sites that are in the EPA list. The problem of acid mine drainage (AMD) contaminates more miles of surface streams than any other type of contamination by hazardous substances. Consequently, these materials will command the research attention of the Rocky Mountain Regional HSRC.

3 RELATION OF THE ISSUES TO THE RESEARCH PLAN

In the initial year of the Center, four research projects were chosen for funding. How do these research projects relate to the examination of the issues presented above? All the projects concentrate on science and engineering rather than politics and sociology. Also, all of the projects are not tied to a particular mining site, so the results could be transferred to any specific project. In the respect that the transfer of the technology can be to any other site, the issue of focusing on abandoned sites is not obvious. However, all of the projects deal with questions that have to be answered at any abandoned site. An examination of how other issues are involved in each specific project follows.

The first research project deals with the availability and transformations of arsenic and selenium in natural environments where organic matter is an important component. At first glance, this project seems unrelated to mining problems. However, this is a key area where the science is lacking to make the proper decisions on how treatment should proceed. For the heavy metals such as Cu, Zn, Pb, and Cd, principles of geochemistry and microbiology can be applied to treatment situations with a good degree of certainty. For the most part, the metals remain in one positive oxidation state and the precipitation sequence for carbonates, hydroxides, and sulfides is well known. However, for As and Se there are multiple oxidation states. In some of these oxidation states, removal is quite difficult. Furthermore, both these elements can occur in volatile compounds and their fate and transport in a removal system confuses the issue. So, for these two contaminants, fundamental scientific questions about speciation, transformation, and fate in biogeochemical systems have to be answered. Currently, we are designing treatment systems for arsenic and selenium. However, if pressed, we cannot answer questions about the ultimate fate of arsenic and selenium in these systems.

There are thousands of tailings and waste rock piles throughout the Western United States that are the relics of earlier mining operations. The questions that even the casual observer asks are: How are all those piles going to be treated, does every one of those piles have to be treated, and are there really contaminants moving from those piles into the surface and ground water? At present, the answers to the questions of which piles are contributing the most to the contaminant load in a watershed and which contaminants are coming from which pile are not known. In addition, material may move from the pile only during severe storms, and the material that moves may not dissolve but rather travel to a stream as suspended solids. However, upon reaching and entering the stream, the continuous contact of the material with the water may result in dissolution and thereby contribute to the contaminant load in a watershed. The answers to these questions are also unknown. Project 2 on the fate and transport of metals and sediment in surface water addresses these questions. Ultimately, because the cost is so great, treatment of waste piles will only be accomplished when there is a sufficient scientific basis to justify the cost. That basis can only developed when good models for the fate and transport of contaminants in waste pile are developed.

Over the past decade, passive treatment is one method for the removal of contaminants from AMD that has been extensively investigated. Passive treatment meets the criteria of being an innovative and lowcost solution. Because they require no utilities and do not need constant attention, passive treatment systems are especially attractive for treating contaminants in mine drainage at abandoned sites. Because the objective in treatment is to fix the problems at the lowest possible cost, the criteria that are used in the design of these systems have never been thoroughly investigated. Because designs are made using incomplete criteria, failure sometimes occurs and the reasons for failure are not understood. However, enough is understood so that the weak points in the design are known. So, these areas need to be investigated so that passive treatment systems can be made more reliable and efficient. These systems rely on the activity of microbes to produce products such as sulfide and carbonate that form precipitates with the metal contaminants. A key question is just what can be added to the system to increase the activity of the microbes? Another key question is whether some of the contaminants are toxic to the microbes? Also, there is a nagging question of whether the organic material that is used in these systems causes the dissolution of the contaminants through complexation. In Project 3, these and other questions concerning passive bioreactor systems will be answered so that this promising method of water treatment can be made to be more reliable and efficient.

Finally, there are the skeptics on both sides of a mine treatment project. One side says, "How do you know that you really have to carry out this expensive remediation?" This side especially focuses on waste rock piles, and sometimes argues that removal means destruction of part of our mining heritage. On the other side says that, if you don't remove all the piles and clean all the sediment from the stream, then achieving a natural ecological condition is impossible. Obviously, both sides have to be convinced that a middle ground exists and that there is a good scientific basis for defining what is the middle course of action. Project 4 addresses these specific issues, and deals with the questions of deciding whether a contaminant in a stream is really toxic to the aquatic ecosystem and determining under what conditions that toxicity is more or less severe. If good information is available for answering these questions, then using this data along with the answers to the questions raised in Project 2 can be used to pinpoint what waste rock piles should be removed to provide the greatest benefit to watershed restoration.

4 SUMMARY

Hopefully, the above exposition helps to inform how Rocky Mountain Regional Hazardous Substances Research Center (RMRHSRC) will go about solving the problems associated with the remediation of mining waste sites. Also, the people associated with the Rocky Mountain Regional HSRC have a strong desire for people to understand the issues that were considered in formulating the initial action plan. To the extent that important issues have been overlooked, the intent of this paper is to solicit responses from the stakeholders so that such issues can be addressed and included with the Center activities in the future.