Former Galmoy Mines Tailings Restoration Project

Former Galmoy Mines tailings restoration Cora Devoy1, Linda Wrong1, Kevin Collins2

1Environmental Manager, Lundin Mining Corporation, [email protected] 1Director of Sustainability and Regulatory A airs, Lundin Mining Corporation, [email protected] 2Bird Watch Ireland - Tipperary Branch, [email protected]

Abstract Galmoy Mines completed the restoration of a tailings management facility (TMF), in- corporating an engineered wetland, returning the site to a land use compatible with the surrounding countryside, while e ciently treating surface water runo and creating an enhanced environment for local and migratory bird species. Increased breeding density of Curlews (IUCN Red List), in addition to nesting Little Ringed Plover and a Glossy Ibis were observed, demonstrating biodiversity support. e wetland system improved post-closure water quality. Ammonia in the revegetated caps of the TMF has stabilised and reductions in the sulphate were noted as the TMF remediation matures. Keywords: Mine Closure, Wetland, Biodiversity, Little Ringed Plover, Ammonia, Sul- phate

Introduction of the progressive rehabilitation of Phase 1 Galmoy Mines zinc-lead deposit, located in (9.36 Ha) and Phase 2 (14.02 Ha) of the TMF south-central Ireland, discovered in 1986 was completed during mine operation. TMF (Doyle 2016), was owned and operated by drainage design allowed for the safe discharge the Lundin Mining Corporation since 2005. of water during the operational and post-clo- Most of the underground mine workings sure stage. e three main sources of water were between 100 m and 160 m below sur- identi ed were seepage water from the inter- face, hosted in extensively dolomitized and nal drainage within the cells (potentially con- brecciated basal Waulsortian (Lower Carbon- taminated), tailings surface water discharged iferous) “Reef” mudbank limestones Produc- from the TMF (potentially contaminated), tion of concentrates at Galmoy commenced and clean surface water reporting to the pe- in early 1997, with mine production carried rimeter drains (Golder 2011). out by room-and-pillar and bench-and- ll e mine operated under an Integrated methods as reported by Lowther et al. (2003). Pollution Control Licence, Planning Permis- During the operational phase, the excess sions, and State Mining Licences [Environ- non-acid generating tailings from process- mental Protection Agency (EPA) 2002; Local ing ore were disposed of in the TMF, with Authorities (Kilkenny County Council) 1994; drainage reclaim water pumped to the mine Department of Communications, Climate site, treated and discharged to the licensed Change, & Environment (DCCAE) SML 1, discharge point (River Goul). e surface 6, 8-10 (1994–2005)]. All licenses and per- area of the TMF measures 33.64 Ha and is missions referred to the rehabilitation of the an engineered double HDPE lined ring dam TMF as an integral part of the Mine Closure built from local glacial materials with chim- Plan (MCP). In the MCP 1992, the preferred ney and nger drains of sand (Derham 1999). option for rehabilitation was the develop- While the original concept of three adjoining ment of a “general amenity/wildlife sanctu- cells remained constant; the numbering, size, ary”, with interim and nal drainage schemes and sequence of construction changed due incorporated into the post-closure periods to revisions of the life of mine and discovery using a combination of wet/dry landscapes of new orebodies, a ecting the underlying on the surface of the TMF. At that time, the principles behind the original design. Most long-term maintenance requirements were

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envisaged to be minimal and a “walk-away” mum concentrations are below the upper end-point would not pose a threat to the threshold of the concentration ranges that environment. However, modern legislation, could be considered excessive in leaf tissue. regulators, and Galmoy Mines recognised Perkins et al. (2015) suggest low translocation the retention of water below the crest of the factors, noted at Galmoy TMF, indicate the dam wall did not o er a “walk-away” solu- positive potential future use of remediated tion. e Second Interim Mine Closure Plan TMFs for uses including pastoral agriculture, (2005) envisaged a wetland located externally even where the soil layer is very thin. to the southwest of the TMF, however at the Successful sheep grazing trials in 2008 announcement of unplanned early closure in and subsequent cattle trials in 2011 and 2012 2009 Phase 3 of the TMF remained partially were conducted on Phase 1 to con rm the ag- un lled and the closure design of the TMF ronomic value of the rehabilitated cap. Analy- required modi cation. sis was conducted on the grass; the animals’ liver, kidney and muscle tissues; and blood Methods samples at the end of each trial. e practical TMF rehabilitation at Galmoy Mines began experience and analytical information from in 2001 with a pilot-scale tailings dam con- the grazing trials demonstrated the ability structed to mimic the conditions in the TMF of the grassed cap to support livestock that, at closure. Pilot trial cells were established at slaughter, complied with all the relevant in compliance with planning permission re- regulatory requirements for animals to safely quirements. e trial cells were subdivided, enter the food chain. and a variety of grass species and depth of A variety of organic materials and gla- substrate were investigated with a mixture cial till substrates were approved for use by of topsoil and compost assessed. Nine cul- the EPA throughout progressive remediation tivars were selected on the basis of a litera- of Phase 1 and 2 (Figure 1), including black ture search and the experience gained at Tara spent grains, limed sewage sludge, kieselguhr Mines, Navan Ireland (Brady 1993). Vegeta- (a form of diatomaceous earth used in various tion trials demonstrated that the grasses se- manufacturing and laboratory processes), ef- lected for the large-scale TMF remediation uent screenings, sludge from BulmersTM ci- (Festuca rubra cv. Merlin, Agrostis castellana der production, topsoil from the borrow area, cv. Heriot and Agrostis capillaris cv. Hyland) and composted products. e aim was to pro- were based on genetic or physiological toler- vide a sustainable growing medium to sup- ance to metals, low uptake of lead and zinc port a natural and vibrant vegetation cover, to allow for the possibility of grazing animals, however, the organic material cover on Phase and good surface coverage and sustainability 1 and 2 generated e uent with high levels of vegetation density. of BOD, COD, ammonia, nitrate, phospho- Based on these trials, capping and reveg- rus and potassium, during the early stages of etation of TMF Phase 1 began in 2001, with remediation which would likely require pas- subsequent monitoring of the performance of sive treatment presenting a challenge to long- the cover through the collection and analy- term discharge compliance, due to elevated sis of soil and vegetation samples. Calcula- ammonia concentrations in particular, in the tion of a bioconcentration factor by Perkins interstitial layer of the vegetation cap. et al. (2015) suggests no accumulation of the A wetland trial was designed by Vesi En- As, Cd, and Pb studied in the roots of grass vironmental Ltd., in 2009 whereby two cells growing on the Galmoy TMF. e data would were constructed adjacent to the TMF. Both suggest that grass species growing on the Gal- cells were planted with four types of wetland moy TMF are relatively successful in exclud- species (Glyceria maxima (main species), ing metals, taken up by the roots, from trans- Carex riparia, Cladium mariscus and Alisma ferring to the remainder of the plant. Recent plantago-aquatica) and irrigated using water studies by Perkins et al. (2015) have shown from the TMF spillway and surface runo , to that the maximum As, Cd, and Pb in herbage assess the impact on the wetland plants of the on Phase 1 and the trial cells are within the parameters of interest. normal ranges for plants and that all maxi-

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Figure 1 Final layout and design of TMF, wetland, and attenuation to licensed discharge (oriented North)

e remediation of partially lled Phase considered doming their tailings facility to 3 (8.29 Ha) presented an additional challenge eliminate the long-term risks associated with in the closure process. Approval was received containment and spillage of surplus water. from the authorities to redesign TMF Phase Following the passive treatment of Phase 1 3 and develop an integrated constructed wet- and 2 surface waters in the ICW, P4 discharge land (ICW) on the surface area of the partially directed towards the attenuation pond lo- lled Phase 3 (Figure 1). e innovative loca- cated northwest of Phase 2 is polished, prior tion of the ICW within Phase 3, was designed to discharge through the post-closure outfall to reduce the footprint of the tailings runo to Glasha stream(Figure1). e surface area area and remediate Phase 3 simultaneously. of the attenuation pond is approximately 2.4 e deposited tails in Phase 3 required resur- Ha, with a capacity of 50,000m3 and varies facing before the ICW could be constructed in depth due to the undulating nature of the on the capped surface. Designed by Golder limestone bedrock. Construction of the ICW Associates (2011), Phase 3 was capped with commenced within the boundary of Phase glacial till and HDPE liner derived from the 3 of the TMF in 2013, providing an HDPE reduction in the height of the dam wall of the lined area in which to locate the ICW. e partially lled Phase 3. Based on the trial data wetlands were divided into four sequential in 2009, Vesi Environmental Ltd., developed ponds, Pond 1 to Pond 4, with Pond 1 sub- the ICW to treat surface runo water report- divided into Pond 1A and 1B and were com- ing from remediated Phase 1 (P1) and Phase missioned in October 2014 (Figure2). 2 (P2). Domed capping pro les for Phases 1 and Results 2 allowed surface water to migrate to the pe- Table 1 outlines the results achieved during rimeter interceptor drainage system, thereby the wetland trial (2009) indicating large re- directing the surface runo and interstitial ductions in the concentrations of the chemi- drainage through redesigned spillway sys- cal species monitored. Based on the trial re- tems to the newly established ICW. Golder sults, the ICW design was nalised by Vesi. (2011) notes that very few mine operations Construction of the full-scale wetland was

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Figure 2 Aerial view of Galmoy Mines constructed wetland (September 2016)

Table 1. Trial wetland results in 2009 (Carty 2017)

Table 2. Wetland e ciency results in 2015 - 2017 discharge vs % removal (Carty 2017)

completed in 2014, with the wetland com- of the discharged water was monitored. Dis- missioned sequentially as each pond in the charge from the nal pond to the attenuation ICW was lled. Discharge through the spill- pond commenced in January 2015. Discharge way system from Phase 2 was commissioned ow from the Pond 4 to the attenuation pond in October 2014, with ow commissioned is managed using a low- ow sensor pump. through the spillway at Phase 1 in November Based on the tailings hydrochemistry, 2014. As each stage progressed, the quality wetland pilot trials (2009), and the proposed

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Total Ammonia Concentration at Galmoy TMF and ICW with rainfall 30 250

25 200

150 mg/L)

( 15 3 NH

100

50 5

0 0 Jan-15 May-15 Oct-15 Mar-16 Aug-16 Jan-17 Jun-17

Rainfall P1 P2 P4

Figure 3 Total Ammonia concentration discharged from TMF Phase 1 (P1) and Phase 2 (P2) and ICW discharge point (P4) vs rainfall 2015 to 2017

discharge water quality limits, a number of onstrate the e ectiveness of the ICW to treat parameters were selected to monitor the re- ammonia. e variable nature of the data is moval e ciency compared to the ELV since most likely due to the impact of rainwater the commissioning of the wetland in October on water quality discharge at the P1 and P2. 2014 (Table 2). e gaps in the data provided are explained Historical data shows that ammonia by no discharge from either the spillways (P1 concentrations tended to be elevated above and P2) or the outfall of the ICW (P4). In ad- normal background levels at the spillways, dition, low concentrations of nitrate in the with a maximum value of 3074mg/L noted runo water of TMF Phase 1 and 2 indicate in 2009 to 48.81mg/L in 2014, attributed to reducing conditions in the organic material. the high ammonium content in the various Elevated concentrations of ammonium and organic materials used to improve the grow- metals appear to be correlated to lower ows. ing medium on the capping layer, particularly Figure 4 illustrates that the sulphate on Phase 1. Figure 3 supports this with TMF concentrations are elevated during various Phase 1 discharge (P1) reporting consistently periods, caused by oxidation of sulphite. El- higher ammonia concentrations than water evated concentrations of sulphate appear emanating from TMF Phase 2 discharge (P2). to be correlated to lower ows from the P1 Figure 3 illustrates the decreasing trends in and P2. Variations in sulphate concentration ammonia concentration at P1 and P2 in re- in the runo water quality appear to re ect cent years (2015-2017) with the trendlines rainfall patterns, based on the available data. demonstrating the maturity of the remediated e trendline at P4 demonstrates that the cap on Phase 1 and 2. Concentrations of am- sulphate concentration has stabilised. e re- monia in the discharge water quality from the duction in sulphate concentrations between ICW are denoted by ICW outfall (P4) dem- 2015 and 2017 in the ICW system are most

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Sulphate Concentration at Galmoy TMF and ICW with rainfall 2500 250

2000 200

1500 150 Rainfall (mm) Rainfall Sulphate (mg/L) Sulphate 1000 100

500 50

0 0 Jan-15 May-15 Oct-15 Mar-16 Aug-16 Jan-17 Jun-17

Rainfall P1 P2 P4

Figure 4 Sulphate concentration discharged from TMF Phase 1 (P1) and Phase 2 (P2) and ICW discharge point (P4) vs rainfall 2015 to 2017

likely attributable to rainfall. Further polish- control site”, “with the TMF study site attract- ing of the discharge water occurs in the at- ing predators such as Merlin and Hen Harrier tenuation pond (approximately 50,000m3) lo- and the establishment of a Black-headed Gull cated on the northwest corner of Phase 2. As colony (IUCN Red List, Least Concern, 2017) with Figure 3, the gaps in the data provided in on the wetland ponds. Figure 4 are due to no discharge from either of the spillways or the outfall of the ICW. Conclusions Of note and in parallel to the remediation e successful restoration of the former mine works, since 2008 Galmoy Mines commis- site, consistent with surrounding land use, sioned biodiversity and bird surveys. Stud- and the development of a fully functional ies focussed on the TMF and a reference site ICW system within the TMF, was the rst located to the northwest of the TMF. Dur- project to complete mine closure activities ing the course of the surveys, Kevin Col- under the EU Mining Waste Directive since lins2 noted dramatic increases in breeding its introduction in 2006. Golder (2011) noted density of Lapwings, Swallows, Sandmarks that the revegetation trial work, in addition and identi ed a wide variety of resident and to the environmental and restoration work is migratory species including the con rmed considered to be following and, in part, ex- presence of the Curlew (IUCN Red List, Near ceeding current best practice for closure in reatened, 2017). Collins also observed a the metal mining industry. e construction nesting Little Ringed Plover at the wetland of the ICW on the partially lled Phase 3 pro- (2015) and a Glossy Ibis (2016), rare species vides a sustainable passive wetland within the in Ireland. Collins (2016) reported “32 spe- former TMF footprint, regulating water ow cies of birds were recorded on the tailing dam and improving water quality in compliance subsite and only 17 species recorded on the with regulatory requirements. In addition,

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the area provides a natural habitat for wildlife References and migratory birds, contributing to a bal- Brady E (1993) Revegetation and environmental anced and functional ecosystem. e remedi- management of lead-zinc mine tailings. M.Phil. ated TMF and ICW act as host to both local, thesis Univ of Liverpool (unpublished) rare and migratory birds as noted by Collins Carty A, Harrington C (2017) Integrated con- (2015) and Collins (2016), structed wetlands (ICW) for mine drainage To utilise the natural processes involving Galmoy Mine case study, Soc Wetland Scientist wetland vegetation, soils, and their associ- (European Chapter) Annual meeting Faro, Por- ated microbial assemblages to assist in treat- tugal 4-6th May ing wastewater (USEPA 2000), the Galmoy Collins K (2016) Wintering bird survey at the ICW was designed to take advantage of many Galmoy Mine rehabilitated tailings dam facility of the same processes that occur in natural (unpublished) wetlands but do so within a more controlled environment. Due to the high organic na- Collins K (2015) Bird Survey at Galmoy Tailings ture of the cover materials on Phase 1 and 2, Dam 2015, Interim Report August 2015 (un- control systems incorporated into the ICW published) ensured the optimum removal of ammonia Doyle E (2016) Ireland’s rehabilitation policy and sulphate from discharge water which had eliminating risk and providing bene ts. Inter- presented challenges at the announcement of national Conference Sustainability of Mineral early closure. Analysis of metals, suspended Resources and the Environment, Conference solids and arsenic from the surface water Proceedings. Ministry of Environment of the were monitored but are not discussed in de- Slovak Republic, Bratislava Page 51-52 ISBN: tail in this paper. 978-80-88833-69-7 It is important to note that the results at Derham J, Dhonau NB, Wright GR (1999) Mine the ICW discharge point (P4) show a 99% closure planning in Ireland: Water aspects. In: reduction in ammonia (2015-2017) and an Fernández Rubio R Mine, Water & Environ- 82%, 84% and 74% respectively, in sulphate ment I. –; International Mine Water Association over the same period. e data serves to dem- Sevilla p. 143-148 onstrate that the ICW is functional, however Environmental Protection Agency (2000) Guiding P4 is not the licensed discharge point. Ad- Principles for Constructed Treatment Wetlands: ditional polishing is achieved downstream Providing for Water Quality and Wildlife Habi- of the ICW at the attenuation pond prior to tat, USEPA 843-B-00-003 discharge to the environment at the licensed EUROPEAN COMMISSION (BREF) Reference discharge point (Glasha stream). Document on Best Available Techniques for Based on the criteria for success detailed Management of Tailings and Waste-Rock in in BREF-MTWR (EC 2009), the attainment Mining Activities January 2009 of a self-sustaining ecosystem at Galmoy was Golder Associates (2011) Tailings management contingent upon the development of a physi- facility at Galmoy Mines, rehabilitation and clo- cally, chemically and biologically stable system sure plan submitted to the EPA (unpublished) founded upon habitat, species and community BirdLife International (2017) e IUCN Red diversity, as well as the restoration of the mine. List of reatened Species, Larus ridibun- Acknowledgments dus, (amended version of 2016 assess- ment) e.T22694420A111823721. http:// e authors thank the Irish Authorities dx.doi.org/10.2305/IUCN.UK.2017-1.RLTS. (DCENR, EPA, KCC, LCC), Vesi Environ- T22694420A111823721.en mental (Wetland Design), Golder Associates BirdLife International (2017) e IUCN Red (TMF engineering), TMB Construction, Ab- List of reatened Species 2017, Numenius erystwyth University, and support from Tara arquata.: e.T22693190A117917038. http:// Mines and Lisheen Mines, in addition to all dx.doi.org/10.2305/IUCN.UK.2017-3.RLTS. the Galmoy sta who worked on the progres- T22693190A117917038.en sive remediation.

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Lowther JM, Balding A, McEvoy FM, Dunphy S, mine wastes, Biology and Environment: Proc R MacEoin P, Bowden AA, McDermott P (2003) Irish Acad 99B(1):11–17 e Galmoy Zn-Pb orebodies: structure and Perkins WT, Bird G, Jacobs SR, Devoy C (2015) metal distribution - clues to the genesis of the Field-scale study of the in uence of di er- deposits. In: Kelly JG, Andrew CJ, Ashton JU, ing remediation strategies on trace metal geo- Boland MB, Earls G, Fusciardi L. Stanley, G chemistry in metal mine tailings from the Irish (2003) Europe’s Major Base Metal Deposits. Midlands. Environ Sci Pollut Res, doi:10.1007/ Irish Assoc Econ Geol, Dublin 437-454 s11356-015-5725-7 O’Sullivan AD, McCabe OM, Murray DA, Otte ML (1999) Wetlands for rehabilitation of metal

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