Patrick Byrne Office of Climate, Licensing & Resource Use Environmental Protection Agency Richview Clonskeagh Dublin 14. IW-ER-LT th June 2014

Transcription

1 Patrick Byrne Office of Climate, Licensing & Resource Use Environmental Protection Agency Richview Clonskeagh Dublin 4 IW-ER-LT th June 204 RE: Kilfenora Certificate of Authorisation Application A Dear Patrick Byrne In response to the Regulation 2(c)(ii) request for further information notice dated the 6th of March 204, please find attached the Hydrogeological Risk Assessment for the Kilfenora Agglomeration as requested. Best Regards, Gerry Galvin Chief Technical Advisor EPA Export :23:44:0

2 Tier 3 Hydrogeology Assessment Kilfenora WWTP Discharge, Co Clare Prepared for Irish Water Colvill House Talbot St, Dublin Prepared by Geosyntec Consultants, Ltd. Botanic Court, Botanic Rd, Glasnevin, Dublin 9. Project Number GCU th June 204 EPA Export :23:44:0

3 Project Title: Project No: Report Ref: Status: Client: Client Details: Tier 3 Hydrogeology Assessment, Kilfenora WWTP Discharge, Co Clare GCU09400 GCU09400/Draft Report Final (Privileged & Confidential) Irish Water Dr Brian Deegan, Colvill House Talbot St, Dublin. Issued By: Geosyntec Consultants Ltd Botanic Court, Botanic Rd., Glasnevin, Dublin 9. Document Production / Approval Record Name Signature Date Position Prepared by Trevor Montague Project Scientist Checked By Graham Webb Principal Engineer Approved by Jim Wragg Project Director & Principal Hydrogeologist Kilfenora Tier 3 Assessment Final.docx i EPA Export :23:44:0

4 LIMITATION Geosyntec Consultants Ltd (Geosyntec) has prepared this Report for the sole use of Irish Water in accordance with the Agreement under which our services were performed. No other warranty, express or implied, is made as to the professional advice included in this Report or any other services provided by us. This Report may not be relied upon by any other party without the prior and express written agreement of Geosyntec. Unless otherwise stated in this Report, the assessments made assume that the site and facilities will continue to be used for their current purpose without significant change. The conclusions and recommendations contained in this Report are based upon information provided by others and upon the assumption that all relevant information has been provided by those parties from whom it has been requested. Information obtained from third parties has not been independently verified by Geosyntec, unless otherwise stated in the Report. Where assessments of works or costs required to reduce or mitigate any environmental liability identified in this Report are made, such assessments are based upon the information available at the time and may be subject to further investigations or information which may become available. It is therefore possible that cost estimates, where provided, may vary outside stated ranges. Where assessments of works or costs necessary to achieve compliance have been made these are based upon measures which, in Geosyntec s experience could normally be negotiated with the relevant authorities under present legislation and enforcement practice, assuming a pro-active and reasonable approach by site management. COPYRIGHT This Report is the copyright of Geosyntec Consultants Ltd. Any unauthorised reproduction or usage by any person other than the addressee is strictly prohibited. Kilfenora Tier 3 Assessment Final.docx ii EPA Export :23:44:0

5 TABLE OF CONTENTS EXECUTIVE SUMMARY.... INTRODUCTION GENERAL INTRODUCTION OBJECTIVE AND BACKGROUND INFORMATION RECENT SITE ASSESSMENTS D. DREW (TCD) TRACER STUDY D. DREW (TCD) TRACER STUDY CLARE COUNTY COUNCIL MONITORING DATA ENVIRONMENTAL SITE SETTING GEOLOGY REGIONAL HYDROGEOLOGY LOCAL HYDROGEOLOGY GROUNDWATER QUALITY SURFACE WATER FEATURES CONCEPTUAL SITE MODEL (CSM) POTENTIAL SOURCE TERM PATHWAYS RECEPTORS SPR LINKAGES RISK SCREENING GROUNDWATER COMPLIANCE MONITORING.... CONCLUSIONS & RECOMMENDATIONS... 6 Kilfenora Tier 3 Assessment Final.docx iii EPA Export :23:44:0

6 LIST OF FIGURES Figure : Location of Kilfenora WWTP & Hydrogeological Features Figure 2: Schematic of Effluent Migration from Kilfenora WWTP Discharge Figure 3: Groundwater Bodies (GWBs) in Study Area Figure 4: Schematic Hydrogeological Cross Section Appendix A: References LIST OF APPENDICES Appendix B: Clare County Council Monitoring Water Quality Results Appendix C: Kilnaboy & Leamaneh Group Water Scheme Water Quality results Kilfenora Tier 3 Assessment Final.docx iv EPA Export :23:44:0

7 EXECUTIVE SUMMARY Geosyntec Consultants Ltd (Geosyntec) was commissioned by Irish Water to complete a Tier 3 risk assessment of a municipal Waste Water Treatment Plant (WWTP) effluent discharge to groundwater located in Kilfenora, Co Clare. The Kilfenora WWTP is understood to provide secondary treatment (activated sludge unit) for sewage form a population equivalent of 280. The discharge location is to a stream at the point where it enters the Ballybreen swallow hole, located in the townland of Ballybreen approximately 600m to the west of Kilfenora village. As such it is deemed to be a direct discharge to groundwater. Clare County Council originally applied for a discharge certificate in This process is now being managed by Irish Water. As part of the application the EPA requested that a Tier 3 risk assessment for the site was completed in accordance with the 20 EPA Guidance on the Authorisation of Discharges to Groundwater and the EPA (204) Guidance on the Authorisation of Direct Discharges to Groundwater. Geosyntec consider that the current discharge is a direct discharge to groundwater in accordance with the EPA guidance and the groundwater regulations underpinning this guidance. However, we understand that Irish Water have commissioned consulting engineers to design an upgrade to the WWTP at Kilfenora to include an appropriately engineered percolation system or other measures designed to reduce the pollutant loading from the discharge. This will have the effect of ending the direct discharge to groundwater and improve the final effluent quality. Geosyntec have therefore completed this assessment on the assumption that the WWTP is in the process of being upgraded. The regional geology is dominated by carboniferous limestone. This limestone is karstified meaning large open conduits exist in the limestone which can transport groundwater great distances over relatively short periods of time. This rapid migration of groundwater (and dissolved or suspended contaminants) is such that beyond dilution and dispersion, little or no contaminant attenuation occurs within the groundwater system between a pollutant source and a receptor. Tracer studies of the Ballybreen swallow hole in 200 and 202 confirmed that the water sinking at Ballybreen is primarily connected to a series of springs approximately 6.km to the south east of Ballybreen (Figure ). These springs form the head waters of the River Fergus. Under high flow conditions a component of the flow was also demonstrated to impact on the Cloongarve stream around.6km to the west. The 202 tracer study also demonstrated connection to a series of domestic water supply wells to the east of Kilfenora. The tracer studies suggest significant conduit flow from the swallow hole to the springs with a lateral diffuse connection to wells to the east (Figure 2). The main contaminants of potential concern (COPC) from the discharge at Ballybreen are considered to be microbial pathogens, nitrogen and phosphorous compounds. It is understood that all of the households using wells identified as being at risk of contamination by the Kilfenora WWTP discharge in the 202 tracer study were offered a mains water connection by Clare County Council. Whilst monitoring of these abstraction wells did provide evidence of impacts to groundwater quality, a Kilfenora Tier 3 Assessment Final.docx EPA Export :23:44:0

8 material impact on the water quality in the River Fergus was not evident at Poplar Bridge, i.e. this stretch has good water quality status with no exceedences of the environmental quality standards for surface water in 203. This is likely to be due to the significant degree of dilution afforded by other inputs to the river. A conceptual Site Model (CSM) was constructed for the site that presents the source, pathway and receptor information for the study area. This information is also presented schematically by Figures 2 and 4. A key element of any risk assessment is the identification and characterisation of the source-pathway receptor relationships that make up the CSM. The tracer studies have confirmed that there are direct connections from the discharge at the Ballybreen swallow hole to both the private water supplies wells in the study area and the River Fergus i.e. viable S-P-R linkages are present. Flow rates over the catchment area were reportedly 7-00m/hr giving an approximate travel time of 2-4 days from the input at Ballybreen to Elmvale Springs and around -3 days to the private supply wells. As such, there is currently a potentially significant risk to human health receptors from the discharge at Ballybreen in the event that abstracted water from impacted wells is ingested without adequate treatment. This issue and the requirement to prevent or limit direct discharges of potentially hazardous substances to groundwater (under the Groundwater Regulations) has resulted in the conclusion that improvements in the degree of treatment provided by the WWTP is required in order to mitigate this risk. This risk assessment has included the development of target quality criteria that if met by the improved effluent treatment at Kilfenora should prevent adverse impacts to the identified receptors. There are currently no requirements to complete groundwater compliance monitoring for the Kilfenora WWTP discharge. However A key aspect of authorisation of discharges to groundwater includes the need for compliance monitoring. The most suitable point for compliance point monitoring is the final effluent discharge point at Ballybreen. It is understood that Irish Water has engaged engineering consultants to complete a design upgrade for the WWTP at Kilfenora. This is understood to examine the possibility of tertiary treatment with either a percolation area or reed bed system to end the direct discharge to groundwater. An ultra violet treatment system will also need to be considered as part of this design to ensure final discharges do not include microbial pathogens. Geosyntec recommend water quality data at the discharge point to aid in the assessment of potential impacts from the discharge to the aquifer. Water quality at the spring discharge will be required to meet surface water environmental quality standards. It is recognised that due to the rural location other inputs into the system from diffuse sources such as agriculture and OSWWTs may be impacting groundwater quality. The Tier 3 risk assessment should be revisited upon completion of the engineering upgrades to the WWTP. Monitoring data form the discharge can be completed over this period which will allow for a more complete assessment to be made. Kilfenora Tier 3 Assessment Final.docx EPA Export :23:44:0

9 . INTRODUCTION.. GENERAL INTRODUCTION Geosyntec Consultants Ltd (Geosyntec) was commissioned by Irish Water to complete a Tier 3 risk assessment of a municipal Waste Water Treatment Plant (WWTP) effluent discharge to groundwater located in Kilfenora, Co. Clare. In 2009 Clare County Council applied for a certificate of authorisation from the Environmental Protection Agency (EPA) for the direct discharge of final effluent from the WWTP to groundwater via a local swallow hole. Since the application was submitted, Clare County Council has been in dialogue with the EPA in relation to the application. At the time of writing it is understood a certificate of authorisation for the discharge had not been issued by the EPA. In parallel with this dialogue with Clare County Council, the EPA was developing guidance on the authorisation of discharges to groundwater, which was published in 20. More recently (January 204) the EPA issued further draft guidance specifically in relation to direct discharges to groundwater 2. As outlined above, it is understood that the Kilfenora WWTP discharges direct to groundwater via a swallow hole. It is our interpretation that the current discharge does not in comply with the requirements specified in the above-mentioned EPA guidance and the groundwater regulations underpinning this guidance for the authorisation of direct discharges to groundwater. This is due to potentially deleterious nature of the discharged water. Specifically we do not believe that the current discharge falls within any of the permissible or exempted pollutant inputs defined by Regulations 8 & 4 of the Groundwater Regulations (S. I. No. 9 or 200). With this in mind, we understand that Irish Water has commissioned consulting engineers to provide a scheme to improve the level of treatment at the Kilfenora WWTP through the inclusion of an appropriately engineered percolation area. An ultra violet treatment system may also need to be considered as part of this assessment to avoid microbial pathogen contamination. The Tier 3 risk assessment presented herein has been completed on the assumption that the improved treatment measures will be put in place and as such, that the discharge will at that stage be a deemed an indirect discharge. Clare County Council recently transferred ownership of the Kilfenora WWTP to Irish Water as part of the migration of all local authority water infrastructure assets to the recently established semi-state body Irish Water. Hence this report has been prepared for Irish Water rather than for Clare County Council. EPA, 20; Guidance on the Authorisation of Discharges to Groundwater 2 EPA, 204; Guidance on the Authorisation of Direct Discharges to Groundwater Kilfenora Tier 3 Assessment Final.docx EPA Export :23:44:0

10 .2. OBJECTIVE AND BACKGROUND INFORMATION Kilfenora is a small village located close to the southern side of the Burren National Park, approximately 27 km north-west of Ennis, 8 km north-east of Ennistymon and 9 km south-east of Lisdoonvarna in County Clare. The existing Kilfenora WWTP, which was constructed in 974, is located to the west of the village. The WWTP currently includes an activated sludge unit with final effluent discharging directly to a swallow hole situated approximately 600m to the west of the village at Ballybreen. There are proposals to upgrade the WWTP; however up to the date of asset transfer to Irish Water from Clare County Council, the local authority had not received the necessary funding to enable this upgrade to proceed. Clare County Council is understood to have considered other treatment of the effluent including a percolation area, to end the direct discharge. The primary aims of the study are to satisfy a request from the Environmental Protection Agency (EPA) for a Tier 3 risk assessment for the above discharge, taking into account planned improvements to upgrade the WWTP. This request from the EPA is linked to correspondence relating to an application lodged with the EPA by Clare County Council in December 2009 for a Waste Water Discharge Certificate of Authorisation for Kilfenora WWTP (Application number A0079-0), as required by the Wastewater Discharge (Authorisation) Regulations, 2007 (S.I. No. 684 of 2007). The overarching goal of the Tier 3 risk assessment is to demonstrate the site s future compliance with the Groundwater Regulations (S I No. 9 of 200). The Groundwater Regulations aim to give effect to the measures needed to achieve the environmental objectives established for groundwater by the Water Framework Directive (WFD) and the Groundwater Directive (GWD). Quoting from Regulation 2 of the Groundwater Regulations, the objectives of the WFD include the following: prevent [in the case of hazardous substances] or limit [in the case of nonhazardous substances] the input of pollutants into groundwater and to prevent the deterioration of the status of all bodies of groundwater, protect, enhance and restore all bodies of groundwater and to ensure a balance between abstraction and recharge of groundwater, with the aim of achieving good groundwater status by not later than 22 December 20, the reversal of any significant and sustained upward trend in the concentration of any pollutant resulting from the impact of human activity in order to progressively reduce pollution of groundwater Kilfenora Tier 3 Assessment Final.docx EPA Export :23:44:0

11 The range of substances deemed hazardous and non-hazardous from a groundwater quality perspective are set out in the EPA (200) guidance Classification of Hazardous and Non Hazardous Substances in Groundwater. None of the listed hazardous materials are known to be present in the discharge at Ballybreen swallow hole. However, the non-hazardous materials listed in the EPA 200 guidance that are likely to be present in the discharge include ammonium, nitrate and phosphate. Whilst the EPA 200 guidance does not explicitly reference microbial pathogens (e.g. coliform bacteria, E. Coli, Enterococci, Cryptosporidium) These pollutants are covered by other statutory instruments such as the European Communities (Drinking Water) Regulations 2000 (S.I. No. 439 of 2000)..3. RECENT SITE ASSESSMENTS The most relevant documents that are available for the Tier 3 assessment are two tracer studies completed by Dr David Drew (Trinity College Dublin) on behalf of Clare County Council. These tracer studies are the only site specific work completed to date from which it is possible to gauge the current impact of the WWTP discharge. The scope and findings of these studies are summarised below..3.. D. Drew (TCD) Tracer Study 200 Clare County Council initially commissioned Dr Drew to undertake a tracer test study at the Ballybreen swallow hole (i.e. the discharge point of the Kilfenora WWTP) in June and July of 200. The main aim of the initial tracer study was to determine the location of the outlets from the swallow hole and comment on how this interacts with the local hydrology and hydrogeology of the area. A series a tracer tests were completed using fluorescent dyes during periods of high and low spring, stream and river flows. Thirteen monitoring points were sampled (8 springs and surface water locations). These are illustrated by Figure. The following conclusions were drawn in the report produced for this study: At low flow conditions, water from Ballybreen flows only to springs feeding the upper part of the River Fergus catchment to the east. Estimated groundwater velocities are in the order of approximately 60-2 m/hr At high flow conditions (following a period of prolonged heavy rainfall) water from Ballybreen flows to all of the springs in the middle River Fergus valley. Groundwater velocities for this condition were estimated to be in the order of m/hr. In addition, under high flow conditions, connection was identified from the Ballybreen Swallow Hole to the Cloongarve stream to the west. Groundwater velocities to that location were estimated to be in the order of 0 m/hr The highest tracer concentrations (indicating the strongest connectivity with Ballybreen swallow hole) were recorded at the Roughan then Poulnaboe and then Elmvale Springs to the east (See Figure ) No direct connection between Ballybreen and Drumcliff or Pouladower Kilfenora Tier 3 Assessment Final.docx EPA Export :23:44:0

12 Springs was noted during either tracer test D. Drew (TCD) Tracer Study 202 Clare County Council commissioned an additional tracer study of the swallow hole at Ballybreen in 202. The main aim of this study was to better characterise the underground flow path(s) between the Ballybreen swallow hole and its known reappearance in springs feeding the River Fergus upstream of Lough Inchiquinn to the east. A particular emphasis was placed on assessing if water from Ballybreen may be being intercepted by several private domestic water supply wells located between the swallow hole and the springs feeding the River Fergus. The main findings of the report were: Five domestic wells (see Figure ) and three springs were sampled during the tracer study Tracer was detected in four of the boreholes sampled during the study demonstrating a connection between the Ballybreen discharge and these wells. Only the samples collected from the Killinaboy GWS well (the most easterly well in the study) were found to contain no detectable tracer Tracer was also detected in two springs feeding the River Fergus, again demonstrating a connection between Ballybreen and these springs Groundwater flow rates estimated from this test were in the order of 7-00 m/hr. These values are understood to be similar rates measured on the Burren The main conclusions of the report are that whilst conduit flow predominates between Ballybreen and the spring outlets to the east there is also a component of lateral dispersion to the north and south which accounts for the detection of tracer in the domestic supply wells which are likely located at offset positions from the main flow conduit system. A schematic diagram of the groundwater flow described above in conduits and laterally through dispersion for both high and low water table conditions is illustrated in Figure Clare County Council Monitoring Data Clare County Council has provided the monitoring results for the Kilfenora WWTP for 203. The results are included as Appendix B. Influent and effluent water quality was monitored monthly for Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD) and Suspended Solids (SS) as per the Urban Waste Water Directive (UWWD) conditions placed on the WWTP. All effluent samples were below their respective emission limit values. BOD/COD/SS pollutant loading reductions were 96%, 88% and 86% respectively through the current treatment system. Flow rate data for the WWTP influent for the year 203 was also provided from Kilfenora Tier 3 Assessment Final.docx EPA Export :23:44:0

13 Clare County Council in this spread sheet. The average influent flow rate for the year 203 was 46 m 3 /day with a maximum of 304 m 3 /day. The data for the Poplar Bridge monitoring location was also included for the period Poplar Bridge is a monitoring location used by Clare County Council on the River Fergus downstream of where the Ballybreen discharge resurfaces in the head waters of the River Fergus (see Figure ). The surface water samples collected on a monthly basis at Poplar Bridge are analysed for ph, BOD, dissolved oxygen, ammoniacal nitrogen, nitrate, nitrite, total organic nitrogen, orthophosphate and total phosphorous. It is noted that these results represent surface water quality at a receptor i.e. the River Fergus. The water quality results are consistent over the period with little change in any of the parameters analysed with the exception of total phosphorous which has decreased from an average of 0.6mg/l in 2009 to 0.08 mg/l in 203. The European Communities Environmental Objectives (Surface Waters) Regulations (S.I. No 272 of 2009) provides surface water Environmental Quality Standards (EQS) that can be used to provide an indication of the surface water quality at the discharge point. Applying these standards to the Poplar Bridge monitoring data shows the levels of BOD, dissolved oxygen saturation and ammoniacal nitrogen at the monitoring point indicate a High status surface water body. There is no EQS available for orthophosphate or total phosphate (the EQS being for Molybdate Reactive Phosphorous (MRP)). 2. ENVIRONMENTAL SITE SETTING Kilfenora village is located close to the southern edge of the Burren National Park, approximately 27 km north-west of Ennis, 8 km north-east of Ennistymon and 9 km south-east of Lisdoonvarna. Kilfenora is a small village in a rural location. The WWTP is immediately surrounded by agricultural land with a school close by to the south. A private dwelling is constructed to the east of the WWTP in relatively close proximity to the site boundary. The existing Kilfenora WWTP was constructed in 974, and is located to the western outskirts of the village. The WWTP includes an activated sludge unit with final effluent discharging directly to a swallow hole situated approximately 600m to the west of the village at Ballybreen. The locations of the WWTP and the discharge point at Ballybreen swallow hole are illustrated by Figure. 2.. GEOLOGY The regional geology of the Kilfenora area is dominated by Dinantian Pure Bedded Limestone s to the east (Lissylisheen and Ballyelly members) and Namurian Shales (Clare shale formation) to the west. The discharge point of the WWTP at Ballybreen swallow hole lies close to the boundary between the Carboniferous Limestone and the Namurian Shales. Locally Ballybreen is surrounded on all sides by shale except Kilfenora Tier 3 Assessment Final.docx EPA Export :23:44:0

14 to the east. Drew (202) describes the local geology of the area as having a series of swallow holes along the eastern boundary between the shales and the limestone including the Ballybreen swallow hole. Karst features dominate the Burren and previous tracer studies by Drew (see Section.3 above) demonstrate that conduit flow is significant in the area as illustrated by the very rapid groundwater velocities measured through tracer testing. Local to the WWTP the thickness of subsoil is unknown but likely to be thin or absent based on the GSI designated aquifer vulnerability of extreme with rock at surface/karst features. Further the Teagasc subsoil database describes the subsoil in the area as Karst, indicating no subsoil in the area with Karst at the surface. No borehole or trial pit logs are available to confirm the geological sequence at the WWTP. As such there is likely to be limited potential to develop a percolation system at the site using the natural soil profile as part of the planned upgrades. It is understood the treated effluent discharge point at Kilfenora is currently directed to a stream that bypasses any subsoil and directly enters the Karst limestone bedrock via the Ballybreen swallow hole REGIONAL HYDROGEOLOGY As stated above in Section.3, tracer studies have shown that the water sinking at Ballybreen swallow hole is hydraulically connected to springs to the east which feed the head waters of the River Fergus. There is also a component of flow that feeds a spring or springs to the west during high water levels. The Geological Society of Ireland (GSI) classifies the aquifer in the study area as a regionally important aquifer Karstified (conduit). The Namurian Shale to the west is classified as a poor aquifer bedrock which is generally unproductive. The 202 tracer study identified wells in the catchment area between Ballybreen and the spring system to the east. All of these wells were shown to be in hydraulic connection with Ballybreen, albeit through a weaker connection than the main conduit connections with the spring system. The Groundwater Body (GWB) underlying the majority of the study area is identified by the EPA as Craggaunboy GWB. The approximate GWB boundaries in the study area are shown in Figure 3. Craggaunboy GWB is classified by the EPA as a poorly productive aquifer. However, the previous tracer studies have demonstrated that the limestone bedrock in the study catchment area exhibits karstic features which would suggest that a Karst Aquifer classification may be more accurate for this GWB. The classification for both the neighbouring Burren and Ennis GWBs is Karst with the latter containing the spring system to the east which has been demonstrated to be connected to the Ballybreen swallow hole and which in turn provide the head waters of the River Fergus. The Water Framework Directive (WFD) risk score for Craggaunboy GWB is possibly at risk of not achieving good status. The WFD risk score for Ennis GWB is at risk of not achieving good status. The WFD risk score for the Burren GWB is Kilfenora Tier 3 Assessment Final.docx EPA Export :23:44:0

15 strongly expected to achieve good status. There is no groundwater quality data available from the EPA monitoring programme for the study catchment area. The current EPA groundwater quality status ( data) for Burren and Craggaunboy GWBs is good, with the Ennis GWB status given as poor. There are no known source protection zones (either EPA or GSI) in the study area LOCAL HYDROGEOLOGY Little additional information beyond the results of the tracer studies is currently available to characterise the local hydrogeological conditions. Specifically, it has not been possible to obtain records for any boreholes drilled in the area, there is limited groundwater elevation data contained within the tracer study and no pump test results have been obtained. No other information in relation to the Ballybreen Swallow Hole characteristics locally is understood to be available. The tracer tests have demonstrated that the main flow zone under dry weather is to the east towards the River Fergus Spring system with a component of flow locally from Ballybreen to the west under high flow conditions. Currently available information on water quality in the catchment area is summarised below GROUNDWATER QUALITY Groundwater monitoring was completed in May 202 by Clare County Council as a follow up to the April 202 tracer study. Monitoring wells identified as having a connection with Ballybreen during the tracer study were sampled for pathogens. A summary of the results for these analyses is presented in the table below. The results below are all samples collected prior to any treatment. The results for the Roche well (not thought to have been included in the 202 tracer study) are included as provided by Clare County Council. The Roche well is understood to be located in the townland of Lisket, Kilfenora. Bacteriological Monitoring of Private Wells in May 202 Clare County Council Monitoring well I.D. Clostridium Perfringens (cfu/00ml) Coliform bacteria (mpn/00ml) E. Coli (mpn/00ml) O Dea (Ballygannor) NA 78 4 NA Keane (Lisket) NA < < NA Mellet (Ballybane) NA < < NA Roche (Lisket) NA >20 6 NA Leamaneh 3 prgws) NA Cryptosporidium (count/0l) 3 Leamaneh prgws was sampled on five occasions between 9 th April and 3 st May 202. Pathogenic bacteria were detected on each occasion when analysed. The table above presents the maximum detection over the monitoring period. The results are for groundwater prior to treatment. It is noted that all pathogenic bacteria were non-detect for Lemenagh after treatment over the monitoring period. Kilfenora Tier 3 Assessment Final.docx EPA Export :23:44:0

16 cfu: colony forming units mpn: most probable number NA: Not analysed prgws (Private Group Water Scheme) Upon completion of the May 202 monitoring programme Clare County Council put in place a programme of upgrades to the water distribution network. Leamaneh prgws was decommissioned and all other households in the monitoring programme were offered connection to a mains supply. A comparison has been undertaken of the bacteriological monitoring results with the tracer test data obtained in April 202. The tracer test identified the Keane well as having the strongest connection to Ballybreen swallow hole. However the Keane pathogen monitoring was non-detect for the specific microbial species tested for in the May 202 samples. This result is anomalous as the Roche well also thought to be located in the townland of Lisket was heavily impacted by microbial pathogens. Overall three of the five wells tested positive for microbial pathogens. However, the results must be treated with caution as it is not possible to rule out other sources of microbial contamination detected in these wells such as OSWWTS. Clare County Council has also completed routine monitoring of the Kilnaboy prgws and Leamaneh /Roughan prgws over the period The results are attached as Appendix C. The Leamaneh well is located approximately half way from Ballybreen to Elmvale Springs and the Kilnaboy well is located to the southeast of Roughan Springs close to the River Fergus. Both wells are downgradient of the Ballybreen discharge (see Figure ). Positive detections have been recorded for Coliform bacteria including E. Coli over the monitoring period at both wells. 2.. SURFACE WATER FEATURES The nature of the Karst geology in the study area means that surface water and groundwater are closely connected. As stated above a series of swallow holes in the west close to the limestone-shale boundary are connected via Karst conduits to springs feeding the headwaters of the River Fergus located from approximately -6 km to the southeast of Ballybreen. The tracer studies summarised above also demonstrate that a component of groundwater flow (especially under high flow conditions) travels to the west to feed the local surface water system at Cloongarve stream which is part of the River Dealagh catchment which ultimately discharges to Liscannor Bay. Clare County Council provided Geosyntec with surface water quality monitoring at Poplar Bridge on the River Fergus over the period (Appendix B). The Poplar Bridge monitoring location is down stream of the main spring discharges forming the River Fergus and up stream of Lough Inchiquin (Figure ). The results Kilfenora Tier 3 Assessment Final.docx EPA Export :23:44:0

17 are summarised in Section.3.2. Overall the surface water quality of the River Fergus in this location is classified by the EPA as good. Considering that the water quality measured at the Poplar bridge location represents inputs not only from the current discharges to the Ballybreen swallow hole but also OSWWTS and other diffuse sources such as agriculture the inputs at Ballybreen swallow hole do not appear to be materially impacting surface water quality in the River Fergus. 3. CONCEPTUAL SITE MODEL (CSM) Outlined below is a summary of the conceptual Site Model (CSM) which describes the potential source term, contaminant migration pathways and potentially exposed receptors associated with the proposed discharge to the Ballybreen swallow hole. A schematic cross section illustrating the CSM is presented as Figure POTENTIAL SOURCE TERM As outlined previously, the Kilfenora WWTP discharge point is the Ballybreen swallow hole. Clare County Council undertakes routine monitoring of the final effluent from Kilfenora WWTP prior to discharge (as discussed in Section.3 above). The results of the Kilfenora WWTP monitoring programme for 203 are included as Appendix B. Presently the discharge is monitored for BOD, COD and suspended solids as per the UWWT directive. Microbial pathogens are not analysed as part of the Kilfenora WWTP monitoring programme. The table below gives a summary of the final effluent quality at Ballybreen and the efficiencies achieved as part of the treatment process for 203. Summary of Final Effluent Quality from Kilfenora WWTP 203 Flow (m 3 /day) BOD (mg/l) COD (mg/l) Susp. Solids (mg/l) Average Maximum Emission Limit Value Actual Loading reduction percentage N/A N/A 96% 88% 86% Kilfenora Tier 3 Assessment Final.docx EPA Export :23:44:0

18 Summary of Final Effluent Quality from Kilfenora WWTP 203 Required loading reduction percentage 4 N/A 79-90% 7% 90% N/A: Not applicable The final effluent discharge point is to a stream immediately before this enters the Ballybreen swallow hole. The flow rates and water quality parameters of this stream (and therefore any potential dilution of the effluent) before it enters groundwater are unknown. At the time of preparing this draft report, Clare County Council has commenced in an intensive period of monitoring the final effluent discharge for Pathogens, as well as N and P species to better characterise the current final effluent discharge. As outlined previously, the main contaminants of potential concern (COPC) from the discharge at Ballybreen are considered to be microbial pathogens, nitrogen and phosphorous compounds. The EPA 20 Guidance on the authorisation of discharges to groundwater states the following in relation to microbial pathogens: Although the Groundwater Regulations focus on chemical substances, and do not explicitly reference microbial pathogens (e.g. coliform bacteria, E. Coli, enterococci, Cryptosporidium), these pollutants are nonetheless covered by other statutory instruments such as the European Communities (Drinking Water) Regulations, 2000 (S.I. 439 of 2000). The drinking water regulations state that drinking water should be free from microbial pathogens, therefore any detection of same in drinking water supply is a fail. Nitrogen and phosphorous species are the key compounds in eutrophication of surface waters (especially phosphates) and therefore are included as COPCs. As outlined previously, it is anticipated that an upgraded WWTP at Kilfenora would need to achieve relatively stringent discharge criteria. We have based the remainder of this risk assessment on the basis that the current direct discharge will need to achieve substantially more stringent quality than those that are likely to be being achieved at present. A set of criteria based on protecting receiving waters are set out in the following table. It is noted that an ultra violet treatment system will also need to be considered as part of this design to ensure final discharges do not include microbial pathogens. 4 The required loading reduction percentage as defined in the Urban Waste Water Treatment (UWWT) Directive (9/27/EEC) as provided by Clare Co Co Kilfenora Tier 3 Assessment Final.docx EPA Export :23:44:0

19 Potential Final Effluent Design Parameters for Kilfenora WWTP Parameter Emission Limit Value Source of Emission Limit value BOD (mg/l) 2 Current Criteria as per UWWTD COD (mg/l) 2 Current Criteria as per UWWTD Suspended Solids (mg/l) 3 Current Criteria as per UWWTD MRP (µg/lp) - No human health criteria for phosphorous compounds Nitrate (mg/l NO 3) Ammonium (µ/l N) Nitrite (µg/l NO 2) GTV protective of water intended for human consumption GTV protective of water intended for human consumption / Drinking Water Standards (SI 278 of 2007) GTV protective of water intended for human consumption E. Coli (counts/00ml) Enterococci (counts/00 ml) Clostridium Perfringens (counts/00 ml) MRP; Molybdate Reactive Phosphorous GTV: Groundwater Threshold Value 3.2. PATHWAYS < Drinking Water Standards (SI 278 of 2007) < Drinking Water Standards (SI 278 of 2007) < Drinking Water Standards (SI 278 of 2007) The key contaminant migration pathways for effluent discharged to the Ballybreen Swallow hole have been established in the tracer studies completed by D. Drew (TCD) in 200 and 202. The tracer tests established that groundwater flow in the area is dominated by Karst conduit flow predominantly in a northeast to southwest direction along a network of solution enhanced bedrock fractures. The tracer test estimated that groundwater flow in the region of 7-00 m/hr over the study area from Ballybreen to Elmvale Springs some 6.km to the south east (similar to groundwater velocity estimates over much of the Burren). Other features of the tracer test data was a component of flow from the Ballybreen swallow hole migrating west towards the Cloongarve stream to the west under high flow conditions (potentially resulting in the connection of a separate higher elevation and westerly orientated conduit system (see Figure 2). The detection of tracer in abstraction wells, in the 202 Tracer Study, located at varying distances to the north of a line between the swallow hole in the west and the main springs receiving water from Ballybreen to the east implies a component Kilfenora Tier 3 Assessment Final.docx EPA Export :23:44:0

20 of lateral flow in a more northerly (and potentially southerly) direction away from the swallow hole. This is a relatively unusual feature in Karst groundwater flow and may potentially result in relatively widespread impacts to groundwater quality in the aquifer when compared to impacts that are more focused along isolated conduits. Figure 2 gives a schematic representation of the flow components described above RECEPTORS The following receptors for discharges made to the Ballybreen Swallow Hole were positively identified in the 200 and 202 tracer studies (refer to Figure for locations): Lisket (Keane) well approximately 2.2km from Ballybreen Ballybane (Mellet) well approximately 3.2 km form Ballybreen Ballygannor (O Dea) well approximately 3km from Ballybreen Leamaneh well approximately 3.2 km from Ballybreen Elmvale Springs approximately.4km from Ballybreen Kilnaboy Springs approximately.9km from Ballybreen Springs feeding the Cloongarve stream 0.6Km to the west form Ballybreen under high flow conditions (See Figure 2). It is noted that all users of wells identified as being potentially impacted in the 202 tracer study were offered connection to mains supply and the Leamaneh GWS was decommissioned. It is recognised that there may be other unregistered wells in the area that use the Karst aquifer for drinking supply. The River Fergus which receives water from Elmvale Springs is also considered to be a receptor. An Appropriate Assessment (as per the EPA guidelines on Appropriate Assessment for WWTP) was completed for the River Fergus as part of the discharge certificate application made by Clare County Council for Kilfenora WWTP. The River Fergus is a designated surface water under the European Communities (Quality of Salmonid Waters) Regulations (S.I. 293 of 988). The assessment concluded that no impact linked to the discharge from the treatment plant is observed or considered likely on Salmonid species, taking account of the effluent quality and the high status of the receiving waters downstream of the discharge SPR LINKAGES RISK SCREENING The following Source-Pathway-Receptor linkages are noted for the effluent discharge at Ballybreen swallow hole: Human Health (Bedrock Aquifer) The final effluent from the Kilfenora WWTP discharges directly to the Karst aquifer Kilfenora Tier 3 Assessment Final.docx EPA Export :23:44:0

21 system via the Ballybreen swallow hole. There are wells in the study area that are using groundwater for drinking water supply. There is a potential for drinking water to be impacted by pathogenic bacteria from the currently discharged effluent. The 202 tracer study identified private wells in hydraulic continuity with the Ballybreen discharge. Subsequent sampling of these wells for microbial pathogens was positive in three of these wells (Section 2.4). Whilst the pathogenic bacteria may be sourced from other inputs such as private OSWWTs the positive detections of tracer suggest the potential for a contribution from Ballybreen. It is noted that all wells positively identified in the 202 tracer study have been offered a mains water supply but not all may have accepted. As such preliminary risk screening for this S- P-R linkage categorises the potential risk as to human health receptors as high where treatment of the abstracted water is ineffective. However upon completion of the upgrade works to the WWTP the pollutant linkage will be addressed at the source, reducing the potential risk significantly. Ecological Water Quality in the River Fergus The 202 tracer study identified a direct link between Ballybreen and the upper reaches of the River Fergus. Surface water quality data from Poplar Bridge (on the River Fergus indicates that discharges from the final effluent are not having an adverse impact on the water quality of the River Fergus (Section.3.2). Considering the fact that the discharges from other sources such as agricultural inputs and OSWWTS could be contributing to the detections at Poplar Bridge and that the results indicate a good water quality status the potential risk associated with this S- P-R linkage is low. It is understood that no monitoring of water quality is undertaken for the Cloongarve stream which periodically may receive water from the Ballybreen swallow hole under high flow conditions, as such it is not possible to evaluate the degree of impact, if any, resulting from this connection. 4. GROUNDWATER COMPLIANCE MONITORING There are currently no requirements to complete groundwater compliance monitoring for the Kilfenora WWTP discharge. It is noted that guidance for the authorisation of discharges to groundwater includes for setting compliance points for monitoring potential impacts to receptors. At the time of writing Clare County Council were engaged in an intensive monitoring programme for microbial pathogens, N& P species at the Kilfenora WWTP discharge point. As other inputs to the aquifer (such as diffuse agricultural inputs or OSWWTS) may result in false positive detections in the GWB the most sensible location for compliance monitoring is at the discharge point of the final effluent at Ballybreen. Routine monitoring of the surface water receptor is on-going by Clare County Council at Poplar Bridge. Water quality results at this receptor should comply with surface water Environmental Quality Standards (EQS). Kilfenora Tier 3 Assessment Final.docx EPA Export :23:44:0

22 . CONCLUSIONS & RECOMMENDATIONS The final effluent from the Kilfenora WWTP is currently discharging to a swallow hole in the townland of Ballybreen to the west of the village. Clare County Council applied to the EPA for a discharge certificate for this practice in As part of the application process the EPA requested a risk assessment to consider the likely impacts that this discharge was having on receiving groundwater and surface waters. The discharge criteria of the final effluent for BOD/COD and suspended solids are routinely passed. There is no requirement to complete any other water quality monitoring at present at the plant. However, we consider that the current discharge is non compliant with the requirements specified in the EPA guidance and the groundwater regulations underpinning this guidance. Specifically with regards to authorising a direct discharge to groundwater with regards to specific constituents of the discharge. As a result, we understand that Irish Water has engaged consulting engineers to design upgrades to the Kilfenora WWTP to include a percolation system. This means that the final effluent water quality will improve and the discharge itself will no longer be classified as a direct discharge to groundwater. An ultra violet treatment system will also need to be considered as part of this design to ensure final discharges do not include microbial pathogens. Tracer tests completed in 200 and 202 have identified a direct linkage between the swallow hole and springs to the southeast which feed the headwaters of the River Fergus. Further private wells in the catchment area were also shown to be hydraulically connected. These wells were subsequently sampled for microbial pathogens in 202 and found to be impacted. A mains water supply was offered to all affected wells by Clare County Council. The main flow zone was direct along conduits as is typical for Karst limestone systems, albeit with a component of dispersion to the north and south to potentially impact water quality in private wells. There is little groundwater quality data available for the study area. Surface water quality at the River Fergus has shown to have a good status. A conceptual site model was developed presenting all known source pathway receptor linkages. The CSM relies heavily on the pollutant linkages suggested by the tracer studies completed for the area. The main substances of potential concern in the current discharge are microbial pathogens and N and P species. Direct linkages between the swallow hole at Ballybreen and private wells in the study area represent the main risk driver for the study area. A pollutant linkage with the River Fergus is confirmed however surface water monitoring of the River Fergus shows that it is currently not impacted form the discharge at Ballybreen. It is recognised that upgrades to the WWTP at Kilfenora will significantly reduce the potential human health risks by breaking the pollutant linkage at the source. Kilfenora Tier 3 Assessment Final.docx EPA Export :23:44:0

23 Geosyntec recommend water quality data at the discharge point is collected to aid in the assessment of potential impacts from the discharge to the aquifer. The most appropriate location for monitoring microbial pathogen compliance is at the discharge point at Ballybreen. Water quality at the spring discharge will be required to meet surface water environmental quality standards. It is recognised that due to the rural location other inputs into the system from disuse sources such as agriculture and OSWWTs may be impacting groundwater quality. Respectfully submitted On behalf of Geosyntec Consultants Ltd oo00oo Trevor Montague Project Manager Jim Wragg Project Director Kilfenora Tier 3 Assessment Final.docx EPA Export :23:44:02

24 FIGURES EPA Export :23:44:02

25 Location of Kilfenora WWTP Cloongarve stream Ballygannor borehole Lisket borehole Ballybane borehole X Leamaneh GWS borehole Roughan/ Fergus spring River Fergus Poplar Bridge X Paulnaboe spring Elmvale spring Kilnaboy GWS borehole Co n se nt o f c Fo op r i yr ns ig pe ht ct ow ion ne pu r r rp eq os ui es re o d nl fo y. ra ny ot he ru se. Swallow Hole at Ballybreen (location of final effluent discharge) Ordnance Survey Ireland. All rights reserved. Licence number: EN Scale :2000 Location of Former Tracer Sampling Sites & Line of Cross-Section (X - X ) Kilfenora WWTP Tier 3 Risk Assessment Irish Water Figure Tracer sampling point selected and utilised by Mr D Drew in report for Clare County Council, 202, entitled Water Trace from Ballybreen Swallowhole. Dublin, Ireland July 204 EPA Export :23:44:02