Department of Communications, Energy & Natural Resources

Environmental Monitoring Services at the Former Mining Areas of Silvermines (Co. Tipperary) and Avoca (Co. Wicklow)

Avoca Monitoring Report - Round 2 (2015) Final

Environmental Monitoring of Former Mining Area of Avoca • Monitoring Report Avoca Mining Area – Aug 2015

Document Control Sheet

Client Department of Communications, Energy and Natural Resources Project Environmental Monitoring of Former Mining Areas of

Silvermines and Avoca Project No 95735 Report Monitoring Report for the Former Mining Area of Avoca

– August 2015 Document Reference: 95735/40/DG/23

Version Author Checked Reviewed Date 1 P Barrett R O’Carroll R L Olsen December 2015

Distribution Copy No.

Environmental Monitoring of Former Mining Area of Avoca • Monitoring Report Avoca Mining Area – Aug 2015

Table of Contents

Section 1 Introduction .............................................................................................................. 1 1.1 Objectives and Scope ............................................................................................................................... 1 1.2 Background of Avoca Mining Area .......................................................................................................... 1 1.3 Catchment Description ............................................................................................................................ 1 1.4 Geology and Hydrogeology ..................................................................................................................... 2

1.4.1 Geology......................................................................................................................................... 2 1.4.2 Hydrogeology ............................................................................................................................... 2

1.5 Description of Adit Discharges ................................................................................................................. 3 Section 2 Methodology ............................................................................................................. 5 2.1 Field Sampling Methods .......................................................................................................................... 5

2.1.1 Groundwater Sampling ................................................................................................................ 5 2.1.2 Surface Water Sampling ............................................................................................................... 6 2.1.3 Field QA/QC Samples .................................................................................................................... 8

2.2 Sample Handling ...................................................................................................................................... 9 2.3 Laboratory Sample Analysis ................................................................................................................... 10 Section 3 Data Quality and Usability Evaluation ........................................................................11 3.1 Introduction ........................................................................................................................................... 11

3.1.1 Accuracy ..................................................................................................................................... 11 3.1.2 Precision ..................................................................................................................................... 11 3.1.3 Blanks ......................................................................................................................................... 12 3.1.4 Field QA/QC Samples .................................................................................................................. 12

3.2 Results of Field QA/QC Samples ............................................................................................................ 13 3.2.1 Duplicates ................................................................................................................................... 13 3.2.2 Decontamination Blanks ............................................................................................................ 14 3.2.3 Standard Reference Materials .................................................................................................... 15

3.3 Laboratory QA/QC Samples ................................................................................................................... 16 3.3.1 ALcontrol .................................................................................................................................... 16

3.4 Summary of Data Checks ....................................................................................................................... 17 3.4.1 Field physico-chemical Versus Laboratory Data ......................................................................... 17 3.4.2 Internal Consistency Analysis ..................................................................................................... 19 3.4.3 Comparison of Total and Dissolved Metals ................................................................................ 22

Section 4 Results and Evaluations .............................................................................................23 4.1 Statistical Summary of Analytical Results .............................................................................................. 23

4.1.1 Groundwater Sample Results ..................................................................................................... 23 4.1.2 Surface Water Sample Results ................................................................................................... 24

4.2 Assessment Criteria ............................................................................................................................... 26 4.2.1 Groundwater and Surface Water Assessment Criteria .............................................................. 26

4.3 Comparison to Assessment Criteria....................................................................................................... 29 4.3.1 Groundwater Assessment .......................................................................................................... 29 4.3.2 Surface Water Assessment ......................................................................................................... 30

Section 5 Flows, Loads and Trend Analysis ................................................................................34 5.1 Surface Water Flows .............................................................................................................................. 34 5.2 Loading Analysis .................................................................................................................................... 36

5.2.1 Loading Analysis Methodology ................................................................................................... 36 5.2.2 Loading Results and Discussion .................................................................................................. 36

Section 6 Groundwater Levels and Groundwater-Surface Water Interaction .............................45

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Environmental Monitoring of Former Mining Area of Avoca • Monitoring Report Avoca Mining Area – Aug 2015 6.1 Groundwater Levels .............................................................................................................................. 45 6.2 Surface Water Levels ............................................................................................................................. 47 6.3 Groundwater-Surface Water Interaction .............................................................................................. 47 6.4 Summary of Diffuse Loading ................................................................................................................. 52

6.4.1 Point Source and Diffuse Loading .............................................................................................. 52 6.4.2 Groundwater Gradients ............................................................................................................. 52 6.4.3 Surface Water Flow Data at the EPA Gauging Stations .............................................................. 53 6.4.4 Diffuse Loading Conclusion ........................................................................................................ 53

Section 7 Summary and Recommendations.............................................................................. 54 7.1 Summary of Findings ............................................................................................................................. 54 7.2 Recommendations for the Monitoring Programme .............................................................................. 55 Section 8 References ............................................................................................................... 56

Appendices Appendix A Figures

Appendix B Analytical Data Tables and Assessment Criteria

List of Tables Table 1 Location of Avoca Groundwater Monitoring Points .............................................................................. 5 Table 2 Location of Surfac