Development of a Closure Strategy for an Abandoned Mine Site Producing Acid Mine Drainage (AMD)
THE CHALLENGE: A very large unlined tailings impoundment was producing significant AMD impacting surface and groundwater.
THE APPROACH: A review of existing data was conducted, data gaps identified, and field work was conducted to fill the gaps. A preliminary Conceptual Site Model was developed based on the data and used for development of the final closure strategy.
THE RESULT: Using the Conceptual Site Model, we assisted the client to understand the alternative water management options allowing reduction of costs and minimal impacts from AMD.
Due Diligence - Risk Evaluation of Storage/Handling/Management of Fuel(s) and other Dangerous Goods at Mines Sites Worldwide; inclusive of physical facility competency and waste management procedures.
THE CHALLENGE: Major exposure to pollution events existed at numerous operating mine sites associated with transport (truck, pipelines, rail, shipping), storage (tank facilities – aboveground; underground storage tanks; temporary systems), handling (transfer processes), management (procedures, competency testing, training) of large quantity of liquid fuels associated with the operation of the mine or product processing areas. This project was highlighted as the result of a major fuel loss incident (> 2 million litres diesel product)) into the subsurface.
THE APPROACH: We developed a comprehensive interactive risk evaluation program over an extensive period in consultation with senior management. This program worked through the numerous and variable scenarios associated with the mine sites and operations owned and managed. Staged interaction and working to populate the data required for this risk program was conducted in close consultation with the senior management at the mine sites specifically.
THE RESULT: Thirty-eight (38) mine sites Worldwide were evaluated; for each mine sites an extensive list of action items were developed to define priority stages and focus for minimisation of risks of pollution and impacts to the eco-system management associated with fuel(s) used at these locations. Future capital and expense budgets to limit these pollution risks were defined relative to this program.
Preliminary Site Investigation
THE CHALLENGE: To conduct a Preliminary Site Investigation at a mine operation in accordance with DEC guidelines (Contaminated Sites Management Series) to identify potential sources of soil and groundwater contamination, if any, probable contaminants, probable locations of contamination and if required to make recommendations for further investigation and/or any remediation work that may be required.
THE APPROACH: Together, in accordance with DEC guidelines undertook: Detailed site history investigation including desk top review and interviews; Review of previous environmental investigations; and Detailed site reconnaissance.
THE RESULT: Review of available information and a site reconnaissance identified a number of potential sources of contamination arising from the site’s land use as an operational gold mine and processing facility. We have developed a risk ranking system for all facilities investigated.
Opti-Leach Program
THE CHALLENGE: The existing dormant leaching facility at the mine needed to be re-started.
THE APPROACH: We applied their opt-leach program in which we optimize heap leach operation for a fixed price. Our activities included evaluation, design, and implementation of an improved operational program.
THE RESULT: The dormant facility produces 10 tons Cu/day, up from an initial 4.4 tons cu/day, extraction rate represents 3% per month of the recoverable copper, and net revenues to the client are nearly $0.9 million per month from a facility once believed non-leachable.
Environmental Due Diligence associated with the purchase of an operating Coal Mine
THE CHALLENGE: To qualify and quantify in a limited period of time the environmental exposures associated with the purchase of a specific operating Coal Mine.
THE APPROACH: We conducted a desk top study of all available environmental information associated with the historic operations of the coal mine. A two day site reconnaissance was conducted of the operations to develop an understanding of present operating procedures and programs and to determine the reliability of the desktop information reviewed.
THE RESULT: The works and report were delivered in a two week period that provided the client a reasonable comprehensive evaluation of the sites past and present environmental risk exposures should the property be purchased. The company decided to not purchase the coal mine asset.
Decommissioning Program
THE CHALLENGE: Iron ore deposits were exhausted and the area required interventions for its stabilisation under the geotechnical, hydraulic, biological and social-economic optics, with the aim for sustainable development of land occupation.
THE APPROACH: We evaluated aquatic ecosystem and site specific water quality, studied surface water and sediments, and conducted studies of resident trout and mountain white fish and semi-aquatic mammals, including mink, otter, and raccoon.
THE RESULT: From conducting a very complex and thorough analysis, we were able to gain a favorable settlement for our client.
Cleanup of Sodium Xanthate Material at Mine site
THE CHALLENGE: Sodium Xanthate is a material used in separation process of metals, as a product it degrades to become a gaseous product that is dangerous for humans to inhale. Numerous spillage had occurred at a former operating mine facility, which required cleanup. A health and safety issue had occurred previously at this location.
THE APPROACH: Sodium Xanthate is not listed in regards to appropriate levels of exposure and associated clean up criteria. We evaluated and defined a risk level appropriate to clean up of the contamination issues. Approvals and education of the regulator was conducted relative to the risk aspects associated with this clean up.
THE RESULT: We conducted the clean up and obtained closure on the site.
Application of In-situ Technology
THE CHALLENGE: Groundwater concerns at an inactive Uranium Mine needed to be examined.
THE APPROACH: We designed a bench-scale uranium treatablity tests.
THE RESULT: The test results allowed us to replace the existing ineffective pump and treat system with an in-situ remediation system. The in-situ remediation system significantly reduced the amount of equipment required, operation and maintenance costs, and production of hazardous waste.
Permitting a Coal Mine
THE CHALLENGE: We conducted an environmental baseline monitoring program for a new underground coal mine.
THE APPROACH: We prepared a permit application in accordance with the state and federal guidance to describe operations and present mitigation measures for minimising potential environmental impacts of the mine operations and disturbance.
THE RESULT: We assembled a complete and technically adequate permit document that was accepted by the agencies with minor revisions. We also completed extensive groundwater modeling and developed appropriate mitigation to reduce impacts on water resources. This approach rapidly moved the project forward to issuance of the permit.
Environmental evaluation of 7 mine sites – 5 operating; in preparation for sale.
THE CHALLENGE: Mine sites under consideration produced or had produced silver, gold, lead and other base metals. Numerous processes were used on these sites for separation, smelting and other processing purposes. Waste, leachate ponds, tailings dams and processing areas at the sites had, had numerous spillages (ie. Mercury, etc), leakages and buried materials (such as drums of cyanide). The long history of these sites and variable unknowns added to the challenge of environmental evaluation.
THE APPROACH: We developed a comprehensive program for the evaluation of areas of impact; and conducted a program of assessment that was extensive. A full understanding (qualification/quantification) of the impacts were provided in a number of reports.
THE RESULT: Reports were provided to the client to utilise in the sale program on the mine sites. We assisted on the cleanup and specific issues and worked with the client to ensure a competent interaction with the regulator for closure of issues.
Environmental Management System Audits
THE CHALLENGE: We were contracted by our client to conduct Environmental Performance and EMS Auditing of Gold, Copper and Bulk Commodities Mining Operations at their 5 operations, combination of underground and open pit mining.
THE APPROACH: The audit program included a systematic approach in: Identifying current and potential environmental issues and liabilities; Assessing each site’s conformance with the Company’s EMS; Evaluating legal compliance with environmental legislation and site-specific legal requirements, such as ministerial conditions and licence conditions; Recommendation of corrective measures for non-compliances and non-conformances; and Provision of an action plan for each site.
THE RESULT: Through the conduct of these audits, the Client was able to improve their environmental performance through the adoption and implementation of several best practice environmental initiatives.
Baseline Environmental Audit in Transport of Mineral Concentrate
THE CHALLENGE: Copper Concentrate is a product that is commonly produced by copper mines after crushing and concentrating mine ore. The Concentrate is hazardous to human health and pose a long term effect to environment in an event of an uncontrolled escape or spillage. A baseline investigation for the transport corridor was required to determine the benchmark for any future potential escape of product along the route.
THE APPROACH: We developed a risk based sampling strategy and a program along the 200km transport corridor in consultation with the best practice, West Australian Contaminated Land Assessment Guidelines and in consultation with Department of Environment and Conservation.
THE RESULT: Soil samples were obtained along the transport route at regular intervals to set up a baseline data set of the background levels of potential contamination.
Diversion of a Major Drainage, Copper Mine
THE CHALLENGE: Permanent diversion of a major drainage (US waterway) around the open pit is needed to access valuable copper ore while replacing riparian habitat.
THE APPROACH: A lined channel with 18,000 cfs carrying capacity was designed with innovative grade control structures to facilitate vegetation.
THE RESULT: Construction of the channel began in Spring 2009. The channel includes cut-off walls on both ends and a textured High Density Polyethylene (HDPE) geomembrane liner to minimize infiltration and assure pit slope stability. Articulated Concrete Block (ACB) armors the side-slopes of the channel. Five feet of natural alluvium is placed over the liner between the grade control structures to make up the streambed and facilitate growth of riparian habitat.
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