Report examines the potential of ecological engineering to reduce contamination at the Faro site

Kalin, Margarete A.

van Everdingen, R.O.

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ECOLOGICAL ENGINEERING AND BIOLOGICAL POLISHING FOR DRAINAGE FROM THE FAR0 WASTE ROCK DUMPS (WETLANDS) prepared by: Margarete Kalin R.O. van Everdingen August 31, 1990 LISTOFFIGURES ._.............................................. ii LISTOFTABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LISTOFMAPS ................................................... LISTOFPLATES ................................................. SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ” 1.0 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . .._.................... . 1 2.0 BACKGROUND DATA EVALUATION ............................ 4 2.1 Waste Rock and Existing Tailings ............................ . 5 3.0 SITE ASSESSMENT FOR BIOLOGICAL POLISHING ............... 3.1 Winter Seep Characteristics ................................ 3.2 Locations for Biological Polishing ............................ 29 29 31 4.0 ALKALINE BIOLOGICAL POLISHING WITH CHARA ................ 4.1 Objective of Growth Tests .................................. 4.2 Materials and Methods .................................... 4.3 Chara Toxicity Tests ...................................... 4.4 Other Biological Polishing Agents ............................ 33 33 34 37 41 5.0 ECOLOGICAL ENGINEERING FOR THE CLOSURE OF MINING WASTES FOR FAR0 TAILINGS AND WASTE ROCK ........................ 6.0 MINING VANGORDA-GRUM AND DECOMMISSIONING ............ LIST OF REFERENCES ............................................ . 41 57 59 . . . . i l l . iv . . iv LIST OF FIGURES Figure 1: Figure 2: Figure 3: Figure 4: Figure 5: Figure 6: Figure 7: Figure 8: Figure 9: Figure 10: Figure 11: Manganese/Sodium concentrations in Faro X22 .......... Manganese/Sodium concentrations in Faro X23 .......... Sulphate concentrations in Faro X23 .................. Sulphate concentrations in Faro X22 .................. Sulphate concentrations and loading&low rate for Faro X11 . Sulphate concentrations and loading/flow rate for Faro Xl2 . Field water temperatures for X11 and Xl2 ............. Manganese and Iron concentrations for X11 ............ Manganese and Iron concentrations for Xl2 ............ Thermistor readings from boreholes in tailings area ....... Thermistor readings at long intervals .................. . . . . . . . . 18 . . 18 . . 20 . . 20 . . 24 . 24 25 . 28 . . 28 . . 53 . . 54 Figure 12: Thermistor readings at 4 week intervals . . . . . . . . . . . . . . . . . . . . . . . . . 55 - 111 - LIST OF TABLES Table la: Table lb: Table 2a: Table 2b: Table 3a: Table 3b: Table 4: Table 5: Table 6: Table 7: Table 8: Table 9: Table 10: Waste Rock Data ................................ Waste Rock Data ................................ Tailings Analyses ................................ Tailings Analyses ................................ Licence Groundwater Sample Sites ................... Additional Groundwater Sample Sites ................. Dissolved and Suspended Elements in X23 ............. Water Characteristics of the North Fork of Rose Creek .... Concentrations of Elements in Faro Waste Water ........ Elemental Composition of Biomass from X11 ........... Elemental Concentrations in X11 and Xl2 Water ........ Analysis of Water Collected During Winter from Grum Adit Climate Data for Faro Airport and Faro Mine site ....... . . . . . 6 . . . 7 . . . 10 . . 11 12 & 13 14 & 15 . . . 22 . . . . 30 . . . . 40 . . . . 42 . . . . 43 . . . . 45 51& 52 - iv - LIST OF MAPS Map 1: Water sampling stations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Plate 1: Plate 2: LIST OF PLATES Chara growth experiments at Boojum Research Ltd. . . . . . . . . . . . . 37 Green algae and cyanobacterial mats at Faro . . . . . . . . . . . . . 37 - ” - SUMMARY The objective of this investigation was to ascertain whether a natural means of reducing or removing contaminants could be identified for the mining wastes of the Faro operation. Such measures are collectively referred to as Ecological Engineering and Biological Polishing. Water monitoring data were evaluated and a field trip was carried out in March 1990 to obtain an understanding of the physical conditions of the site. The water characteristics suggest that the most effective means of controlling contaminant release from the tailings and the waste rock would be by enhancement of permafrost and a general encouragement of low temperatures. The manner in which colder temperatures could be encouraged warrants investigation. It is likely that natural contaminant removal processes are occurring in the form of precipitation, biological adsorption, or a combination of microbial H2S production and precipitation. Ecological Engineering and Biological Polishing techniques could enhance the already present contaminant removal processes. Laboratory tests at Boojum Research Ltd. indicate that the macrophytic alga CJzaru vulguris can adsorb significant concentrations of zinc. This, coupled with the fact that other algae and cyanobacteria present at Faro can also concentrate heavy metals such as zinc, provide enough information to suggest that Ecological Engineering and Biological Polishing will significantly reduce contaminant loadings in Faro waste water if properly applied to this site. - 1 - 1.0 INTRODUCTION Waste materials (waste rock and tailings) associated with the former Cyprus Anvil operations at Faro, Yukon Territory, were first produced between 1969 and 1982. Except for some stripping of waste, the operation was dormant until 1986 when milling resumed at a rate of 13,500 tons per day. The Zone II pit has already been mined out and backfilled with waste rock. By 1991, the Faro pit (Zone I/III pit) will be exhausted. The tailings produced since 1986 have been deposited in impoundments below the earlier tailings in Rose Creek valley. Environmental concerns have been associated with this mining operation prior to 1986. These concerns range from high copper and cyanide concentrations, to depression of dissolved oxygen, and finally, elevated zinc concentrations in the water (EPS Reports 81 to 85). Some of the concerns associated with milling practices have already been addressed, but metal leaching due to weathering of waste rock presents a complex long-term problem. At present, treatment of all effluents takes place in the mill and in the tailings pond where, through addition of lime and provision of sufficient retention time, contaminants are removed prior to effluent discharge. Environmental concern has been raised with respect to the post- mining operation phase. Conventional technology, including the installation of water treatment plants and till and water covers over tailings to reduce infiltration of oxygen, are very expensive and the environmental benefits are not readily apparent or quantifiable. - 2 - In the continued search for an environmentally acceptable long-term solution, Boojum Research Limited was retained to examine the existing information from the Cyprus Anvil/Fare site and to identify those potential avenues within the Ecological Engineering approach which may be used to increase the effectiveness of conventional technology. Ecological Engineering methods are based on an understanding of the natural processes which lead to contaminant generation and those which assist in repairing or counteracting environmental degradation. In order to utilize the natural repair mechanisms, a determination of the long-term effluent characteristics is essential, namely their improvement, deterioration or reaching steady state. With this information at hand, measures can be taken towards an environmentally sound closure approach. The long-term performance of acceptable measures for closure can only be determined if the controlling factors of contaminant generation are understood. Furthermore, those factors which assist in the natural removal of contaminants from the water column have to be identified. If the rate of contaminant generation is controlled by infiltration of oxygen and water, then the effectiveness of a cover can be determined through quantification of the reduction of oxygen and water infiltration. If, on the other hand, contaminant generation is controlled by temperature, measures which would enhance low temperature regimes for the waste material would provide an effective long-term management strategy. -3- The objective of Phase 1 of this project is to identify options for the closure plan which are based on an understanding of the natural processes of contaminant generation and removal which may exist in the drainage basin. These natural processes are collectively referred to as “Ecological Engineering and Biological Polishing”. Through a review of monitoring data from the relevant areas (the waste rock dumps and the tailings), and a site visit to become familiar with conditions of the site, some of these processes can be identified. Furthermore, through toxicity tests with the algal family Characeae, (a known biological polishing agent for alkaline waste water), the applications of the Chum process can be evaluated. In Section 2, the background data are reviewed in order to identify the relevant factors which control contaminant release. The impressions obtained during a field trip carried out in March 1990, and their relevance to biological systems for the site, are presented in Section 3. Section 4 gives the results of the Chnru toxicity tests and an assessment of other potential biological polishing mechanisms. Section 5 outlines those components of Ecological Engineering which could be usefully developed for the Faro site. - 4 - 2.0 BACKGROUND DATA EVALUATION Relevant information was extracted from reports and data listings made available by Curragh Resources Inc. These are summarized below. Data are presented, along with comments and recommendations regarding future measurements, sample analyses and data interpretation which would be required to better understand the key factors driving contaminant mobilization and its removal. List of Reports and Data Sources 1. 2. 3. 4. Kerr-AEX Grum Joint Venture, 1975. Biophysical and Socio-Economic Program. Monenco. Environmental Quality of Rose Creek as Affected by Cyprus Anvil Mining Corp. Ltd. EPS Regional Program Report. 79-25. Compliance Evaluation of Cyprus Anvil Mine, FARO, Yukon. EPS Regional Program Report. 81-15. Examination of the Impact of the Discharges from Cyprus Anvil Mine on the Aquatic Environmental Quality of Rose Creek, Yukon. EPS Regional Program Report. 81-25. -5- 5. Oxidation of Yukon Mine Tailings. EPS Regional Program Report. 84-15. 6. Tailings Abandonment Development Program (TADP) Annual Report. S.R.K. July 1989. 7. Faro Pits and Rock Waste Dumps, 1987 and 1988 Seep Surveys. Report No. 60612. 8. Faro Mine Abandonment Plan, Curragh Resources Inc., April 1988. Prepared by R. McLenehan and J. Bowers. 2.1 Waste Rock and Existing Tailings Available sulphur analyses of various waste-rock types from the Faro mine are listed in Table la, together with acid-generation potential (AGP), acid-neutralization potential (ANP) and net AGP values (in kg CaCO, per tonne of waste). Table lb lists estimated total quantities of waste-rock, and estimated total net acid-generation potential (12.6 million tonnes), based on mean net AGP equal to 550 kg/tonne. These estimates indicate the dimensions of the problem, if all pyritic material were converted to sulphuric acid. Although this acid generation potential exists, its environmental impact is dependant on the rate at which the net acid generation proceeds. Available information indicates that weathering would proceed slowly. - 6 Table la: Waste Rock Data A ANALYSES WASTE-ROCK TYPE 1975 gdmplcs (mrrcctcd fram Table 78) Sandy pyrite Biotite schist Quamlmusmvire a&t MuKwitc schiit chlc-ailicatc 2EO 6 5270 1645.4 24.5 1621 ID0 9.2 0.09 2s 13.6 -11 ID4 6.4 3.60 1124 33.6 79 1CD 7.9 0.09 28 18.1 -1s 3D 9.4 0.46 14.4 65.8 -51 2E 59 30.90 9626 2.8 %3 1DO 7.5 1.14 35.6 10.4 25.2 1D4 7.2 4.09 127.8 18.3 110 3D 8.9 0.42 13.2 2l21 -2cm 3DBX 8.5 0.79 24.7 17.9 6.8 PH NET 90s AGP. AN.P. A&P. kgltonne kgltonnc kgltonne ROCK DRAIN and CAUSEWAY samples (mans from Table 16) Biorirc/andaltitc acbist ID0 a3 0.288 9.0 59.9 -50.9 Calcsilicatc b&s 3DBX 9.1 0.20 6.1 79.40 -73.3 From: Fara Mine Abandonmat Plan, CRI, Apcii 1988. AGP and ANP in kg C&O3 squivalcnt per tonne matcriaL -7- Table lb: Waste Rock Data B. QUANTITIES ACID- ULTIMATE CALC-SIL. BlOTlTE MUSCOV. DIORITE GENERATING QUANTITY GNEISS SCHIST SCHIST WASTE ROCK __- -___-._- la millions of EUbiC meters FAR0 MAIN DUMPS UPPERNORTHWESTDUMPS FASTSIDE DUMPS VANGORDA HAUL ROAD PIT DUMPS s.5.w. 18.48 16.24 IO.64 5.04 5.60 5.00 1.75 1.50 1.00 0.X 0.25 23.0-3 8.05 6.94 4.6n 2% 1.1s 5.00 204 1.X 1.04 0.50 0.00 3.00 0.60 0.54 0.36 0.18 1.32 TOTALS 92200 I” miliom (11 tonnt8, arsuming bulking = 30?& FAR0 MAIN DUMPS 116.31 UPPER NORTHWEST DUMPS IO.38 EAST SIDE DUMPS 47.77 VANGORDA HAUL ROAD 10.38 PIT DUMPS 6.23 38.38 33.73 D-10 10.47 lS.SI 3.63 3.12 208 1.04 0.69 16.72 14.33 9.55 4.78 3.18 4.15 3.12 208 1.04 0.00 1.2s 1.12 0.75 0.37 3.66 TOTALS 191.07 a.13 55.42 36% 17.70 23.04 HE04 lW7VOO TONNES 30.88 26.68 17.60 8.52 8.32 - 8 . This rate will differ for the tailings where the AGP is estimated based on data presented in Tables 2a and 2b. Available sulphur analyses for the tailings are listed together with AGP, ANP and net AGP values (in kg H,SO, per tonne). The net AGP values range from a minimum of 259 kg/tonne to a maximum of 1516 kg/tonne, with a mean of 849 kg/tonne. Using this mean value and a total quantity of about 40 million tonnes of tailings, the total net AGP for the present tailings deposit would be about 32 million tonnes. Rates of contaminant generation can be derived if data exists which facilitates such calculations. The availability of data from which a time series can be derived and a complete accounting of those possible oxidation products is essential. Chemical analyses of water collected in the period 1986 - 1989 from various groundwater sampling sites are listed in Tables 3a and 3b. The groundwater sampling sites for the requirements of the water license are presented in Table 3a. The monitoring data differentiate between unaffected ground water (X16A,B - X17A,B) and water which is affected by the tailings deposit. The differences in concentrations in Mn, Fe, Na and sulphate make these elements worthy parameters for data interpretation. In Table 3b, additional ground water sampling sites are summarized. Those show the same pattern as the X sampling series where the presence of tailings is indicated by the elements Mn, Fe, Na and sulphate. One series of samples (ID 4S, ID 4D and the series 81-04D to K12) shows erratic zinc concentration fluctuations along with a wide range of pH values. 

Ecological engineering and biological polishing for drainage from the Faro waste rock dumps

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Ecological engineering and biological polishing for drainage from the Faro waste rock dumps

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