Galway County Council Comhairle Chontae na Gaillimhe

Transcription

1 Galway County Council Comhairle Chontae na Gaillimhe Annual Environmental Report (AER) 2011 Galway County Council Aras an Chontae Prospect Hill Galway Tuam Waste Water Discharge Licence Granted on the 21 st December 2010 (EPA Ref: D )

2 Annual Environmental Report (AER) 2011 Agglomeration Name: Tuam Licence Register Number: D Licensee: Galway County Council Document Title: Annual Environmental Report (AER) 2011 Date Revision Prepared By Checked By Approved By March 2012 Rev 1 Peter Mitchell Martin Lavelle Jim Cullen Tuam WWTP Water Services Director Plant Manager Senior Engineer Services of To be submitted to the EPA by 28 th February 2012

3 Table of Contents 1. Introduction 2. Summary of Monitoring Reports 2.1. Summary report on monthly influent monitoring 2.2. Discharges from the agglomeration 2.3. Ambient monitoring summary 2.4. Data collection and reporting requirements under the Urban Waste Water Treatment Directive 2.5. Pollutant Release and Transfer Register (PRTR) report for previous year 2.6. Pollutant Release and Transfer Register proposal for current year 3. Complaints and Incident Reports 3.1. Complaints summary 3.2. Reported incidents summary 4. Infrastructural Assessments and Programme of Improvements 4.1. Treatment Capacity 4.2. Storm water overflow identification and inspection report 4.3.Report on progress made and proposals being developed to meet the improvement programme requirements. 5. Environmental Liability and Financial Provisions 5.1. Annual statement on prevention of environmental damage 6. Licence Specific Reports 6.1. Development/Infrastructural works summary (completed in previous year or prepared for current year) Environmental Liabilities Risk Assessment (ELRA) 6.3. Organic Screening of the primary discharge SW1 Appendix I Reported Incidents & Complaints Appendix II AER/PRTR Hard copy report 2011 Appendix III Environmental Liabilities Risk Assessment (ELRA) Report Appendix IV Organic Screening of the Primary discharge SW1

4 1. Introduction A Waste Water Discharge Licence for the Tuam Agglomeration was granted on the 21st December 2010 under the Waste Water Discharge (Authorisation) Regulations This Annual Environmental Report (AER) which shall be to the satisfaction of the Agency shall include as a minimum the information specified in Schedule D: Annual Environmental Report (see table below) of this licence and shall be prepared in accordance with any relevant guidelines issued by the Agency. SCHEDULE D: Annual Environmental Report Source: Waste Water Discharge Licence No: D Annual Environmental Report Content Note1 Discharges from the agglomeration. Summary report on monthly influent monitoring Data collection and reporting requirements under the Urban Waste Water Treatment Directive. Complaints summary. Pollutant Release and Transfer Register - report for previous year. Pollutant Release and Transfer Register - proposal for current year. Ambient monitoring summary. Storm water overflow identification and inspection report. Reported incidents summary. Report on progress made and proposals being developed to meet the improvement programme requirements. Note 2 Development/Infrastructural works summary (completed in previous year or prepared for current year). Any other items specified by the Agency Note 1: Content may be revised subject to the agreement of the Agency Note 2: This summary report shall provide detail on all measures proposed and undertaken under the Water Services Investment Programme for the agglomeration, including progress reports on infrastructural works and a statement of compliance with timeframes set out in this licence. 1

5 2. Summary of Monitoring Reports 2.1 Summary report on monthly influent monitoring A tabular presentation of Tuam waste water treatment plant s influent monitoring results for ph, BOD, COD, Total Suspended Solids, Ammonia, Total Nitrogen, Total Phosphorus and orthophosphate is included below. The average monthly flow from January 1 st to December 31 st 2011 inclusive was 4415m3/d with an average BOD loading of 1241kg. This represents a PE of 20,677 for that period. Tuam Waste Water Treatment Works Influent Date cbod COD S S ph Orthophosphate Total Phosphorus Total Nitrogen (mg/l) (mg/l) (mg/l) (mg/l PO4.P) (mg/l P) (mg/l N) 13/01/ /02/ /03/ /04/ /05/ /06/2011 < /07/ /08/ /09/ /10/ /11/ /12/ Discharges from the agglomeration All parameters required to be tested under Schedule B of the Licence were carried out from 1 st January No odour or colour issues were recorded under visual inspection monitoring on the primary discharge SW1. Date Flow Temp ph Conductivity cbod COD S S Total N Ammonia Total P Orthop Units m3/d deg. Cel µs/cm mg/l mg/l mg/l mg/l Nmg/l NH3.N mg/l P mg/l PO4.P ELV 25 C /01/ /02/ /03/ /04/ /05/ Udr Rge /06/ /07/ /08/ /09/ /10/ <2 < /11/ < /12/ <2 35 <

6 2.3. Ambient monitoring summary Tabular representations of the ambient monitoring results (as per Schedule B.3 of the license) are included below: Upstream sample report of Tuam Wastewater Treatment Works asw1u Grid Ref: (141286E, N) Date ph cbod COD D O Total N NH3.N Total P Ortho P Units mg/l mg/l mg/l mg/l N mg/l mg/l P mg/l PO4.P 10/02/ Udr Rge /03/ Udr Rge /04/ ND 18/05/ /06/ <1 15 Udr Rge /07/ /08/ < /09/ < <.01 20/10/ < /11/ < Downstream sample report of Tuam Wastewater Treatment Works asw1d Grid Ref: (141147E, N) Date ph cbod COD D O Total N NH3.N Total P Ortho P Units mg/l mg/l mg/l mg/l N mg/l mg/l P mg/l PO4.P 10/02/ Udr Rge /03/ Udr Rge /04/ ND 18/05/ /06/ <0 8 Udr Rge /07/ /08/ < <0.05 < /09/ < < /10/ < /11/ < < /12/ <

7 2.4. Data collection and reporting requirements under the Urban Waste Water Treatment Directive. This information was submitted online to the EPA via website on the 24 th of February 2012 by Galway County Council Environment Section under the 2011 EPA Urban Wastewater Returns. 2.5 Pollutant Release and Transfer Register (PRTR) report for previous year. The PRTR for 2011 is included in Appendix II. 2.6 Pollutant Release and Transfer Register proposal for current year. See Appendix II 3. Complaint and Incident Reports 3.1 Complaints summary A complaints register is maintained at Tuam WWTP and one letter of complaint was received by Galway County Council on date 05 th December 2011from Coffey Construction Ltd. which is detailed in Tuam WWTP Complaints Register Template below. The detail of the complaint and response is detailed in Appendix II. Date & Time Name of Nature of Response to Closed (Y/N) Complainant Complaint Complainant 05/12/2011 Coffey Odour nuisance A letter of N Construction Ltd. at Pumping response dated Station 14/12/ Reported incidents summary Eight reportable incidents were recorded and documented between 13th of January and 27th of August 2011 but were not notified to the EPA via . This has been brought to the attention of the EPA since. Seven incidents were reported to the EPA via between the dates of 26 th of August and 18 th of November One incident for December was recorded and reported in January 2012 via the Eden website. A copy of all reported incidents throughout 2011 is included in Appendix I 4

8 4. Infrastructural Assessments and Programme of Improvements 4.1 Treatment Capacity The Tuam WWTP plant caters for a design population equivalent of 24,834 and is currently operating at a capacity of 20,677 as calculated from 2011 influent monitoring Storm water overflow identification and inspection report The operation of the Storm water overflow (SWO) identified as SW1a, SW2 and SW3(emergency overflow) in the licence application was assessed under the criteria set out in Section 4 of the Urban Waste Water Treatment Directive (91/271/EEC) Procedures and Criteria in relation to Storm Water Overflows, and the following is noted: In assessing the operation of an existing SWO, one must determine if it: 1 Causes significant visual or aesthetic impact and public complaints: The Storm water overflows SW1a and SW2do not cause any visual or aesthetic impact or public complaint as the SW1a passes through a 10mm mesh screen and then a secondary 6mm screen. While SW2 passes through the 10mm screen at the Weir Road Pumping Station and there is also a coarse grid screen at the overflow point of Cell 2 of the new storm tank at the Pumping Station. 2 Causes deterioration in water quality in the receiving water: The new storm tank at the Main Pumping station, Weir Road (for SW2) which has been recently commissioned (December 2011) and can now attenuate storm water of approximately 1200m3, which is in addition to the existing 162m3 storm wet well capacity. It is anticipated that the pumping station should not experience more than one spill in a year. Any possible spills have passed through inlet screen which is a 10mm bar raked screen and will pass through a coarse screen also on exiting the Storm Water Cells. Storm Water Overflow SW1a at the WWTP has the capacity to retain 1300m3 of storm water and the system is managed under automatic mode so that when flows subside below 2DWF the storm return pumps drain down the tank to avoid spills or overflows which combine with the final effluent stream. The storm water first passes through a step screen of 6mm mesh size prior to entering the Storm tank. Under prolonged storm conditions and storm overflow occurs there is a high dilution level. The automatic sampler on the primary discharge channel can sample to pick 5

9 up any overflows which will determine any deterioration in final effluent quality following analysis. 3 Operates in dry weather: The Storm water overflows do not operate in dry weather conditions Report on progress made and proposals being developed to meet the improvement programme requirements. Schedule C of the licence states that the following improvements are proposed at the Weir RD pumping station and WWTP. C.1 Improvement Programme for Primary Discharge Specified Improvement Completion Date Upgrade to WWTP aeration system to meet design treatment capacity 31 st December 2012 Any other works notified in writing by the Agency As agreed C.2 Improvement Programme for Storm Water Overflows Specified Improvements Discharge Point Code Completion Date A new Storm water Holding Tank of 1,200m3 capacity, reinforced concrete storm water retention tank was constructed adjacent to the existing main foul pumping station on the Weir Rd. Works included inlet and outlet pipe work, valves, fittings and dealing with existing incoming flows to the pumping station. 6

10 The sewer network integrity The pipeline network included a collection of trunk sewers and surface water pipes, a rising main between the pumping station and the waste water treatment works and an outfall pipeline from the treatment works to the river Clare. Also an outfall pipeline was laid from the pumping station to the River Nanny. The project involved the placing of 7,500m³ of concrete and the laying of 8100m of pipes in varying size from 100mm-900mm diameter. Storm overflow chambers were constructed on existing combined sewers with separate foul and surface water pipes downstream of the chambers. Over 6,500m of pipes ranging in size from 225mm-900mm diameter were laid outside the treatment works. Asbestos cement, concrete and ductile iron pipes were used for gravity flow pipes. Ductile iron and upvc was used for pressure pipes. Depths of pipelines varied from 1.0m to 4.9metres. All pressure pipelines were subjected to a water test and gravity sewers to an air test. On completion of testing a final inspection of gravity sewers was carried out by using CCTV. 116No. manholes were constructed on main sewers ranging in size from 1,200mm to 1,800mm diameter. Ground conditions along pipeline routes varied from peat to silty sandy gravel to rock. A photographic precondition survey was carried out of all pipeline routes prior to commencing work. Pipe laying was carried out by traditional open cut methods. Due to poor ground conditions 2,200 meters of pipeline had to be constructed on piles. Ductile iron pipes were used in piled areas. Pairs of piles were driven and a steel cross head welded to the piles. 7

11 New Tuam Main drainage work contract A CCTV survey was implemented in around This survey identified areas of concern in the network and was one of the bases for the recommendations made in the current contract. The CCTV Survey findings are available at Galway County Council offices for reference. The list below is the new mains storm and foul sewers constructed under the new main Tuam drainage contract. Main Storm and Foul Sewers: 4,872m of 160mm nominal outside diameter structured walled pipe. 5,660m of 250mm nominal outside diameter structured walled pipe. 5,542m of 400mm nominal outside diameter structured walled pipe. 2,460m of 500mm nominal outside diameter structured walled pipe. 1,894m of 630mm nominal outside diameter structured walled pipe. 137m of 600mm Concrete Piping 1,186m of 675mm diameter concrete pipe Associated gully connections Transfer of foul connections to new foul sewers where laid Associated Manholes A relining contract is currently being implemented where certain sewers that were identified in the original CCTV are being either fully relined or partially relined to reinstate the integrity of the pipe and thus the overall collection network. All new storm and foul lines constructed as part of the contract will be CCTV d following completion. Programme of Infrastructural Improvements Existing treatment and capacity of treatment plant: The Tuam WWTP plant caters for a design population equivalent of 24,834 and is currently operating at a capacity of 20,677. Flow is by gravity into the Weir Road Pumping Station and the waste water first goes through a coarse screen. Flows in excess of 6DWF (Dry Weather Flow) are pumped to the new Storm cells prior to any eventual emission to the river Nanny following persistent storm conditions. The main treatment plant fully treats flows of up to 3DWF, while flows in excess of this overflow to a storm water holding tank which has a capacity of 1,300m3, after passing through the secondary fine screen. This storm water is then pumped back to the head of the works when 8

12 the flow to the treatment plant falls below 2DWF. The final stage of preliminary treatment is where Grit is removed using a paddle type Jeta Grit Trap. The grit is lifted to a classifier using an air lift pump; this grit is then washed and discharged to a skip to be disposed of at a landfill site. In the next stage of the treatment, the wastewater flows through two primary sedimentation tanks from a splitter chamber. Their purpose is to reduce the velocity of the incoming effluent, allowing solids to settle at the bottom of the tank. The suspended solids settle by type II sedimentation, i.e. they flocculate during sedimentation and fall to the bottom of the tank producing a primary sludge which is periodically pumped to the sludge stabilization tank for thickening and further treatment. The wastewater overflowing the weirs of the primary tanks now enters the process of secondary treatment and flows into four aeration tanks through another splitting chamber. The function of the aeration tank is to encourage micro-organisms capable of aerobically stabilising the organic content of the waste and to prevent it from settling. Oxygen is introduced into the waste by four 22kW variable speed aerators in each tank. These aerators violently agitate the waste therefore increasing the Dissolved Oxygen (DO) levels and in turn reducing the BOD content. Too much or too little oxygen is undesirable for different reasons. Too much adds cost to the process as more power is being consumed, it also can cause floc shearing while too little can decrease the metabolism of the micro-organisms and therefore reducing the efficiency of the process. The wastewater now flows into two secondary sedimentation tanks. The secondary sedimentation tanks work on the same basis as the primary tanks. However, the design overflow rate is less because of the greater retention time in the secondary tank. Their objective is to remove suspended solids and return a certain percentage of the settled sludge to the aeration tank. Any scum layer that develops on the surface of the tank is scrapped off using a surface skimmer to a scum box. The sludge is returned to the head of the aeration tanks by two variable speed pumps each with a capacity to pump up to 250m 3 /hour. Sludge is also wasted up to the Activated Sludge thickener periodically to ensure that the aeration stage is operating under optimum conditions. The final treatment the wastewater has to undergo before it can be discharged to the River Clare is tertiary treatment. Tuam treatment plant have very stringent measures as 9

13 to the quality of the water it can discharge to the river, because it is a noted salmon, sea and brown trout river with spawning grounds upstream. The sand filter is a shallow bed cellular downward flow filter, made up of 51 units and designed for a loading rate of 4.3 m 3 /m 2 /hr when all compartments are in operation. Backwashing of each unit occurs at least once every 24 hours. They are backwashed with a backwash pump attached to a variable speed moving bridge with a backwash collection hood. The backwash which includes flocs and dirt is then pumped back up to the head of the works for full treatment. Both primary and secondary sludge are collected, thickened and mixed prior to eventual dewatering in the sludge dewatering room by one of two Solids Technology Series 2 Belt Presses. The resulting sludge cake is further stabilized by lime conditioning which raises the temperature and ph of the sludge thereby achieving an acceptable pathogen kill making the resulting sludge suitable for land spreading. Designations of the receiving water body: The primary discharge (SW1) combined with any SW1a discharges from Tuam WWTP discharge into the River Clare via 400 meters outfall pipe, while the Storm Water Overflow at the Pumping Station (SW2) discharges to the River Nanny which is a tributary of the River Clare. There are no designated sensitive waters located in the vicinity of the waste water works and primary discharge. The Water Framework Directive status of each receiving water is as follows: River Clare: WE Corrib Clare Glenafosha and River Nanny: WE Corrib Nanny. The Water Region is the Western Corrib HA30. A Q rating of Q3-4 was assigned to the Clare and Nanny Rivers. The current status of the river Clare water body is Good. The current objective for this water body is to maintain and protect good status. The status of the river Nanny water body is moderate and the timeline to restore to good status is by The River Clare flows into Lough Corrib which is a water abstraction point. The outfall pipe discharges into the River Clare which is within the Lough Corrib csac. The nearest drinking water abstraction point downstream of the WWTP discharge is at the Terryland drinking water plant in Galway City, which draws water from the River Corrib. The drinking water plant is approximately 48 km downstream of the primary discharge point. The Terryland plant operates a conventional co-agulation/filtration treatment system with UV disinfection. Overall, it is not considered to be at risk from discharges from the Tuam WWTP. 10

14 Industrial licensed discharges to Tuam Waste Water Treatment Works: The table below lists the industrial facilities licensed to discharge to the Tuam sewer and any standards and volumetric limitations applied to each as per their license: Facility Name: Facility Address: License Number: Volumetric Limitations: Standards applied: Connaught Electronics Ltd. IDA Industrial Estate, Dunmore Road, Tuam, Co. Galway Tuam Co-operative Mart Ltd. Tuam, Co. Galway Transitions Optical Inc IDA Industrial Estate The Demense Dunmore Road, Tuam, Co. Galway S70/01 S/019/78 S01/98 S/78/04 Daily flow of trade effluent shall not exceed 10m3 and the flow rate shall not exceed 3m3/hour Zinc 1mg/l Lead 0.5mg/l Sulphates 500mg/l Suspended solids 25mg/l BOD 200mg/l COD 450mg/l T Phosphorus 10mg/l T Nitrogen 12mg/l Ammonia 10mg/l Oils Fats & Greases 100mg/l Monthly records of daily volumes of effluent discharged must be submitted COD 600mg/l BOD 350mg/l, BOD loading shall not exceed 15kg/day Suspended solids 100mg/l Ortho Phos 8mg/l T Phosphorus 16mg/l T Nitrogen 15mg/l Oils fats & greases 50mg/l ph Temperature Max. 20deg The discharge of trade effluent shall not exceed 300m3/day or 30m3/hour COD 3500mg/l BOD 1000mg/l Suspended solids 200mg/l ph Temperature 30 deg Oils & Grease 50mg/l OCS One Complete Solutions Ltd. Unit 20, Kilmore, Galway Road, Tuam, Co. Galway Monthly records of daily volumes of effluent discharged must be submitted ph 6-9 Temperature Max.40 deg BOD 300mg/l Suspended solids 250mg/l Detergents 10mg/l 11

15 5. Environmental Liability and Financial Provisions 5.1 Annual Statement on prevention of environmental damage Statement Galway County Council is aware of the environmental risks imposed by the discharges (SW1, SW1a and SW2) from the Tuam agglomeration to sensitive environmental areas such as SACs, SPAs, NHAs, and any other environmental sensitive designated sites and downstream water abstraction points. All relevant sensitive areas associated with the Tuam agglomeration are outlined and considered as part of the license application. Mitigation Measures Galway County Council has a monitoring regime in place, which is aligned with the conditions of the license granted for the discharge(s). The monitoring programme will identify any problems which may occur with the discharge(s) and if required appropriate action will be taken. Galway County Council will make every effort to implement any improvement works required by the license subject to the availability of funding secured. Management of Financial Risk Currently Galway County council does not have an insurance policy to cover for environmental liability as a result of an incident at a waste water treatment works. An Environmental Liability Risk Assessment (ELRA) has been prepared for the waste water treatment works. The ELRA will be forwarded to Galway County Council s insurer Irish Public Bodies Mutual Insurances Ltd (IPB) for review and we anticipate to obtain a quotation for the appropriate liability cover 12

16 6. Licence Specific Reports 6.1 Development/Infrastructural works summary (completed in previous year or proposed for current year). Provision of increased aeration capacity by replacing the existing surface aerators with a fine bubble diffuser aeration system (required to be in place by 31/12/12) Ensure that adequate hydraulic and aeration capacity is available to meet Total Ammonia limits as set out in the Surface Water Regulations (S.I. No. 272 of 2009). Provision of a landfill leachate buffer/holding tank in order to be able to demonstrate compliance with the waste water licence condition that landfill leachate volume intake is to be limited to 4% of the influent hourly volume; and in order to prevent shock loading the plant from landfill leachate. Galway County Council have engaged consultants to prepare a short scoping report setting out design proposals for the aforementioned condition as per Schedule C.1 Specified Improvement Programme, with a cost estimate and options for completing the work within the timescale as set out in the licence. 6.2 Environmental Liabilities Risk Assessment (ELRA) An Environmental Liabilities Risk Assessment (ELRA) has been prepared for the Tuam Waste Water treatment Plant. Refer to Appendix III for the full ELRA Report. 6.3 Organic screening of the Primary discharge SW1 A representative sample of effluent from the primary discharge point (SW1) was screened for the presence of organic compounds and metals. The laboratory contracted to carry out the work was Complete Laboratory Solutions Ltd. Refer to Appendix IV for the full analysis Report. 13

17 14

18 Appendix I Report Incidents & Complaints

19 Ref. Number Date of Notification 1. 13/01/ /02/ /05/ /06/ /07/ /08/ /09/2011 WWTP Name Tuam WWTP Tuam WWTP Tuam WWTP Tuam WWTP Tuam WWTP Tuam WWTP Tuam WWTP Notification type Discharge Licence ELV Exceedance Discharge Licence ELV Exceedance Discharge Licence ELV Exceedance Discharge Licence ELV Exceedance Discharge Licence ELV Exceedance Discharge Licence ELV Exceedance Discharge Licence ELV Exceedance Notification in relation to Total Nitrogen and Ammonia for SW1 Ammonia for SW1 Orthophosphate for SW1 Total Phosphorus and Orthophosphate for SW1 cbod and Ammonia for SW1 Ammonia for SW1 Total Nitrogen and Orthophosphate for SW1 Total Nitrogen, Agencies notified None None None None None EPA via using Notification of incident form EPA via using Notification of incident form Closed (Y/N) Y Y Y Y Y Y Y 8. 18/11/2011 Tuam WWTP Discharge Licence ELV Exceedance Ammonia, Orthophosphate and Total Phosphorus for EPA via using Notification of incident form Y SW /12/2011 Tuam WWTP Discharge Licence ELV Exceedance Orthophosphate for SW1 EPA via Y

20

21

22

23 Appendix II AER/PRTR Hard copy report 2011

24

25

26

27

28

29 Appendix III Environmental Liabilities Risk Assessment (ELRA) Report

30 GALWAY COUNTY COUNCIL Environmental Liability Risk Assessment & Statement of Measures for Tuam WWTP2011 Urban Waste Water Discharge Licence Register Number: D Version Status Compiled by: Date Rev.1 Final Peter Mitchell June 2011

31 Table of Contents 1 INTRODUCTION BACKGROUND ENVIRONMENTAL SENSITIVITY SENSITIVITY OF RECEIVING GROUNDWATER PROTECTI PROTECTED ECOLOGICAL SITES AND SPECIES(SHORTEST DISTANCE FROM ANY DISCHARGE) HUMAN HEALTH RISK ASSESSMENT RISK PREVENTION/ MITIGATION STATEMENT OF MEASURES FINANCIAL PROVISIONS ESTIMATION OF REMEDIATION COSTS DETAILS OF FINANCIAL PROVISION/ INSURANCE... 16

32 1 Introduction This Environmental Liability Risk Assessment relates to the agglomeration of Tuam. This report has been prepared in compliance with Condition of Licence No. D which requires: The licensee shall arrange for the completion, by an independent and appropriately qualified consultant, of a comprehensive and fully costed Environmental Liabilities Risk Assessment (ELRA) to address the liabilities from present or planned discharges. A report on this assessment shall be submitted to the Agency for agreement as part of the second AER (required under condition 6.10). The ELRA shall be reviewed as necessary to reflect any significant change to the volume or character of effluent discharged, and in any case every three years following initial agreement (the results of the review shall be notified as part of the AER). This report was prepared in accordance with the Environmental Protection Agency Guidance on Environmental Liability Risk Assessment, Residual Management Plans and Financial Provision, and the Environmental Protection Agency Guidance on the Preparation & Submission of the Environmental Liability Risk Assessment (ELRA) for the Annual Environmental Report (AER) for Waste Water Discharge Licences. 1.1 Background Tuam Waste Water Treatment Works was commissioned in June of The scheme involved the construction of 6,500 metres of collector sewers, a pumping station and 834 metre rising main and a wastewater treatment works with a design capacity of 24,834 population equivalent. Tuam town is located 32km north of Galway City on the N17 National Primary Route and along the banks of the River Nanny ( Western River Basin District), which is a tributary of the River Clare. It was estimated in 2009 that the population of the agglomeration is approximately 9,000 persons. The Waste Water Treatment Plant (WWTP) is located in Killaloonty on the outskirts of Tuam Town. The WWTP is a conventional activated sludge plant with phosphorus removal and tertiary sand filtration. The WWTP was designed to serve a population equivalent (p.e) of 24,834 (determined in 1988), with dry weather flow loadings of 5063 m3/day volume, 1490 kg BOD/day and 2118 kg suspended solids/day. These are total figures representing domestic, commercial, institutional and industrial effluent sources. The agglomeration is served by a network of foul, storm and combined sewers and a number of pumping stations but is mostly a combined sewerage system. The pumping stations pump effluent into the collection system which then falls by gravity to the main pumping station on the Weir Road in Tuam Town. The Weir Road pumping station includes two foul pumps, which operate on a duty/standby basis. Screened effluent of up to 6 times Dry Weather Flow (DWF) is pumped from the Weir Road pumping station to the WWTP with up to 3DWF receiving full treatment at the WWTP.

33 At the WWTP, flow from the pumping station in excess of 3DWF is diverted to a storm water tank with a capacity of 1300m3. The collected storm water is pumped to the front of the WWTP when flows fall below 2DWF. Phosphorus removal is achieved by dosing with ferric sulphate (chemical precipitation) directly downstream of the aeration tanks. Sludge treatment consists of primary sludge stabilization, thickening, dewatering and lime stabilization. The WWTP accepts leachate from the Greenstar landfill facility at Kilconnell Co. Galway. Sludge s from Galway County Council s waste water treatment facilities are also accepted, ones which do not have their own dewatering facilities. Also septic tank waste is imported from the unsewered Tuam Town environs. Leachate and sludges are accepted for treatment at the WWTP. They are discharged at by tanker to the main pumping station. The irregular nature of this importation can lead to the introduction of shock high BOD and ammonia loads to the WWTP which periodically exerts additional pressure on the treatment capacity of the WWTP. There are no IPPC or EPA licensed waste facilities in the agglomeration or in the vicinity of the agglomeration. 2 Environmental Sensitivity The main considerations in relation to the receiving waters for the discharge have been identified and given a designated score, which are set out in Table 1. Each environmental attribute is described in detail below, which is the basis of the designated score for each attribute in Table 1. The sensitivity of the receiving environment in the vicinity of the facility was assessed, with 2.1 Sensitivity of Receiving Waters The primary discharge (SW1) from Tuam WWTP discharges directly to the River Clare, while the Storm Water Overflow at the Pumping Station (SW2) discharges to the River Nanny which is a tributary of the River Clare. There are no designated sensitive waters located in the vicinity of the waste water works and primary discharge. The Water Framework Directive status of each receiving water is as follows: River Clare: WE Corrib Clare Glenafosha 2 and River Nanny: WE Corrib Nanny. The Water Region is the Western Corrib HA30. A Q rating of Q3-4 was assigned to the Clare and Nanny Rivers, which is of moderate status.

34 2.2 Groundwater Protection The WWTP and Pumping station is underlain by a Regionally Important Aquifer- Karstified (Conduit) with a vulnerability rating of medium at the WWTP and medium to low at the Pumping Station site. The land type of the waste water works area is Amin PDPT peaty gleys, acidic, while the groundwater surrounding lands are B min PDPT peaty gleys, basic parent materials. 2.3 Protected Ecological Sites and Species (Shortest distance from any discharge) The WWTP discharges directly into the River Clare which flows into Lough Corrib which is a water abstraction point. The Primary discharge point is located 400m approx. from the River Clare within the Lough Corrib csac. The RiverClare contain populations of Annex II species of otter, crayfish and lamprey at points on the river both above and below the primary discharge point. The River Clare is not designated as a SPA but populations of Kingfisher and swan (Annex I species) are found on the river. 2.4 Human Health Lough Corrib is a water abstraction point. The Primary discharge point is located 400m approx. from the River Clare. The nearest drinking water abstraction point downstream of the WWTP discharge is at the Terryland drinking water plant in Galway City, which draws water from the River Corrib. The drinking water plant is approximately 48 km downstream of the primary discharge point. The Terryland plant operates a conventional coagulation/filtration treatment system with UV disinfection. Overall, it is not considered to be at risk from discharges from the Tuam WWTP.

35 Table 1 Environmental Sensitivity Assessment Environmental Attribute Attribute Score Designated Score Comment Sensitivity of Receiving Water Class A (Q5,Q4-5,Q4) 3 Class B (Q3-Q4) 2 2 Q3-4 moderate status Class C (Q3,Q2-3) 1 Class D (Q2,Q1-2,Q1) 0 Designated Coastal and Estuarine waters 2 Groundwater Protection Regionally Important Aquifer Locally Important Aquifer 1 Poor Aquifer 0 Vulnerability rating - 3 Extreme Vulnerability rating - High Regionally important aquifer Karstified (conduit) Vulnerability rating Vulnerability rating: Moderate medium-low Vulnerability rating Low 0 Protected ecological Sites and Species (shortest distance from any discharge) Discharge within or 2 directly bordering a designated site <1km 1 >1km 0 0 River Clare Human Health Discharge within or directly bordering a designated shellfish area 0-5km 1 >5km 0 0 Designated Bathing water Within 0-5km 1 >5km 0 0 Drinking Water source Within 0-10km 1 >10km 0 0 Drinking water : Lough Corrib >10km Environmental Sensitivity Score 5

36 3 Risk Assessment Table 2: Risk assessment Table 2 A site visit was undertaken on date 16 th of May. This included a walkover of the WTTP site and visitation of the main pump0 stations accompanied by Galway County Council Staff and the Employers Representative. The risk identification process involved: The identification of potential environment receptors at the site The identification of WTTP processes that posed potential hazards to the environmental receptors The identification of risks associated with the processes The potential environmental receptors and site sensitivity were discussed in Section 2. The Risk Assessment form (Table 2) identifies all risks which are associated with the process. Risk rankings were applied to each risk for severity and occurrence in accordance with the risk classification tables (Table 5 and 6). The overall risk score was calculated for each risk i.e. the risk score is a product of the risk severity and risk occurrence rating.

37 Table 2: Risk Assessment Form Risk ID Process* Potential Hazards Environmental Effect Severity Rating Basis of Severity Occurrence Rating Basis of Occurrence Risk Score New storm tank, 1 Pumping station Dual foul pump trip Excess foul flow to storm, facility and eventually to river 3 Remediation of river Nanny 1 more capacity, Also alarmed to alert caretaker 3 Nanny when foul pump tripped 2 Pumping station Strom pumps trip Unable to pump storm to Storm tank and river, back up of flow and blockages 2 Untreated w.w discharge to groundwater and storm water 3 Alarm to alert caretaker of pump trip 6 Contamination 3 Collection system Blockage Ground water pollution, subsequent impact on environment 3 could be ongoing for a long period of time if leak not detected, groundwater monitoring and pumping maybe 2 Upgrade of collection network and storm overflows currently being carried out 6 required 4 Storm water treatment Uncontrolled and prolonged discharge from storm overflow Discharge of untreated waters to receiving waters 3 Remediation of river and protected habitats 2 New storm water tank for increased storm attenuation 6 5 Inlet works at main Screen blockage and overflow Ground water pollution, subsequent impact on environment 3 Untreated and unscreened raw sewage discharge for a period of time to ground water 3 Alarm to alert caretaker when screen trips 9 Imported Spill on site, septic tank groundwater Spill would be Traffic volume 6 waste Spill on site pollution and 2 intercepted to site 3 low, trained 6 reception subsequent impacts drainage operatives. on water courses 7 Strom tank at main plant Excess discharged to R. Clare Receiving water pollution 3 Remediation of river and protected habitats 2 Control philosophy in place to control and maintain low 6

38 level in storm tank and minimize overflow Failure of 8 Biological treatment Failure of aeration tank biological process, receiving waters depleted of DO, nutrient enrichment, 4 Remediation of river and protected habitats 2 D.O monitoring, Alarm to alert caretakers of aerator trip 8 potential fish kill Receiving waters MLSS 9 Biological treatment Washout of MLSS depleted of D.O, nutrient enrichment, 4 Remediation of rivers and protected habitats 2 monitoring. Trained operatives onsite, monitoring 8 potential fish kills of process 10 Chemical dosingferric dosing Spill or leach onsite Spill on site, groundwater contamination, subsequent impact on watercourses 3 Spill would be intercepted to site drainage, high toxicity 2 Bunded area, fill tank using spring loaded valve 6 11 Clarifiers Failure of critical equipment leading solids to carryover in effluent Suspended solids concentrated in final effluent 2 Impact on receiving waters would be short 3 MLSS monitoring, failure of clarifier unlikely to be sudden/without deterioration of effluent 6 12 Tertiary filter Blockage, backwash failure Spill on site, groundwater contamination, subsequent impact on watercourses 2 Secondary treated effluent, impact on watercourses would be low 3 Standby backwash pump in place 6 13 Chemical dosingpoly Spill or leak onsite Spill on site, groundwater contamination, subsequent impact 2 Spill would be intercepted 3 Bunded areas, trained operatives onsite, quantities would be 6 on watercourses relatively low Spill on site, 14 Importing of leachate Spill/overflow groundwater contamination, subsequent impact 2 Spill would be intercepted by site drainage 3 Traffic volumes low, trained operatives 6 on watercourses

39 15 Laboratory Chemical spill Lab drains to supernatant tank and pumped back to head of plant 2 Spill would be intercepted 3 Quantities of chemicals usually low, training 6 Remediation of 16 WWTP Power failure, generator failure Foul pumping down at the pumping station 4 soils, waters, groundwater s, rivers and protected 2 Standby generator at both sites 8 habitats 17 WWTP Flooding Receiving waters depleted of D.O, nutrient enrichment, potential fish kills 5 Remediation of soils, waters, groundwater s, rivers and protected habitats 1 No historic flooding reported in Tuam WTTP history 5 18 WTTP Tank failure Ground water pollution, subsequent impact on watercourses 4 Contamination could be on going for a long period of time of leak not detected 2 Work carried out by Civil contractor on commissioning of plant 8 19 WTTP Pipe failure Ground water pollution, subsequent impact on watercourses 3 Contamination could be on going for a long period of time of leak not detected 2 Work carried out by Civil contractor on commissioning of plant 6

40 4 Risk Prevention/Mitigation This risk matrix indicates that there are no risks in the red zone requiring priority attention. All risks are located in the green zone indicating a need for continuing awareness and monitoring on a regular basis. However, assessment of the green zone risks during the process has indicated that many of these risks can be reduced through the implementation of mitigation measures. These measures should be adopted where considered cost-effective to further reduce the risks. As these risks may have the potential to increase to yellow or red zone risks, risk management measures should be put in place to manage them at their current levels, or preferably to reduce them further. Risk Matrix: Occurrence V. High 5 High 4 Medium 3 Low 2 V.Low 1 Trivial Minor Moderate Major Massive Severity These are considered to be high-level risks requiring priority attention. These risks have the potential to be catastrophic and as such should be addressed quickly. These are medium-level risks requiring action, but are not as critical as a red coded risk. Green (light and dark green) These are lowest-level risks and indicate a need for continuing awareness and monitoring on a regular basis. Whilst they are currently low or minor risks, some have the potential to increase to medium or even high-level risks and must therefore be regularly monitored and if cost effective mitigation can be carried out to reduce the risk even further this should be pursued.

41 5 Statement of Measures The measures to be undertaken by Galway County Council are outlined in Table 4. Measures are in place within Tuam WTTP are adequate to maintain the discharge at a quality that complies with the license conditions and does not significantly impact on the conservation objectives of the River Clare.

42 Table 4: Statement of Measures: Owner/ Risk Risk Date for Mitigation measure to be taken Outcome Action Contact I.D Score completion person Continue regular maintenance and Reduce risk of Continue regular maintenance and Ongoing Galway 1 3 inspection, Ensure generator are maintained and serviced emergency overflow inspection, Ensure generator are maintained and serviced County Council 2 6 Continue regular maintenance and Reduce risk of Ongoing Galway Strom water overflows, monitoring inspection, put in place documented uncontrolled County assessment report inspection program overflows Council Continue regular maintenance and Reduced risk of Continue regular maintenance and Ongoing Galway 3 6 inspection, put in place documented inspection program blockage and overspill inspection, put in place documented inspection program County Council 4 6 Reduced risk of Put in place documented procedures uncontrolled for inspection overflows Continue regular maintenance, Reduced risk of inspection and service of inlet 5 9 blockage and screen, prompt response to call out unscreened flow alarm Continue regular maintenance and inspection. Put in place emergency 6 6 Reduced risk of procedures for spillages. Put in spill place standard operating procedures for handling of sludge Continue regular maintenance and 7 6 Reduce emission inspection, optimize storm water from storm tank return facility Continue regular maintenance and 8 8 Risk of aeration inspection. Put in place documented failure and inspection program, prompt biological process response to call out alarm Continue regular maintenance and Reduced risk of 9 8 inspection. Put in place documented failure of inspection program, monitoring of biological Activated sludge designed criteria treatment Continue regular maintenance and 10 6 inspection. Put in place emergency Reduced risk of procedures for spillages. Put in spill place standard operating procedures for handling of sludge Continue regular maintenance and 11 6 inspection. Put in place documented Clarifier operation inspection program, regular check secure on sludge blankets Ongoing Galway Storm water overflows, monitoring County assessment report Council Ongoing Continue regular maintenance and Galway inspection. Put in place documented County inspection program Council Continue regular maintenance and Ongoing inspection. Put in place emergency Galway procedures for spillages. Put in County place standard operating procedures Council for handling waste Continue regular maintenance and Ongoing Galway inspection. Put in place documented County inspection program Council Ongoing Galway Continue regular maintenance and County inspection Council Ongoing Continue regular maintenance and Galway inspection. Put in place documented County inspection program Council Continue regular maintenance and Ongoing inspection. Put in place emergency Galway procedures for spillages. Put in County place standard operating procedures Council for handling chemicals Ongoing Continue regular maintenance and Galway inspection. Put in place documented County inspection program Council 12 6 Continue regular maintenance and Tertiary filter Continue regular maintenance and Ongoing Galway

43 inspection. Put in place documented operation secure inspection. Put in place documented County inspection program, Renew filter inspection program Council and as required 13 6 Continue regular maintenance and inspection of Poly IBC bund. Put in place emergency procedures for spillages. Put in place standard operating procedures for handling of chemicals Reduced risk of spill Continue regular maintenance and inspection. Put in place emergency procedures for spillages. Put in place standard operating procedures for handling of chemicals Ongoing Galway County Council Continue regular maintenance and Continue regular maintenance and Ongoing 14 6 inspection. Put in place emergency processes for spillage. Put in place standard operating procedures for Reduced risk of spill inspection. Put in place emergency procedures for spillages. Put in place standard operating procedures Galway County Galway importation of leachate for handling leachate Continue regular maintenance and Continue regular maintenance and 15 6 inspection. Put in place emergency procedures for spillages. Put in place standard operating procedures Reduced risk of spill inspection. Put in place emergency procedures for spillages. Put in place standard operating procedures Ongoing Galway County Council for handling of Chemicals for handling of chemicals

44 6 Financial Provisions. 6.1 Estimation of Remediation Costs The Unknown environmental liabilities are associated with environmental risks and may or may not occur. The best case scenario is that none of the environmental risks occur and hence at the end of the assessment period of 30 years, the additional costs incurred by the County Council are zero. be incurred. Alternatively, should a significant number of risks materialize, significant additional costs could The unknown environmental liabilities are estimated through the use of a financial model. Each risk has two characteristics that are derived from the Risk Classification Tables (tables 5 and 6) that are used in the financial model: The range in cost implications (EA-B) if the risks occurs (Table 5) The range in probability (X-Y%) of the risk occurring (Table 6) Table 5: Risk Classification Table Severity Rating Severity Category Description Cost of Remediation ( 000 s) 1 Trivial No damage or negligible change to the environment Minor Minor impact/localized or nuisance Moderate Moderate damage to environment Major Severe damage to local environment Massive Massive damage to a large area, irreversible in a medium term

45 Table 6: Risk Classification Table Occurrence Rating Occurrence Category Description Likelihood of Occurrence (%) 1 Very Low Very low chance (5%) of hazard occurring in 30 pr period 0-5% 2 Low Low chance (5-10%) of hazard occurring in 30 yr period 5-10% 3 Medium Medium chance (10-20%) of hazard occurring in 30 yr period 10-20% 4 High High chance (20-50%) of hazard occurring in 30 yr period 20-50% 5 Very High Greater than 50% chance of hazard occurring in 30 yr period >50% In order to identify an indicative level of environmental liability associated with the environmental risks for the purposes of the ELRA, a cost model has been used to generate the expected cumulative cost of the risks as outlined in Section 4 of this report. The modeling has been undertaken using the median probability and severity of occurrence of each risk (Table 7).

46 Table 7: Financial Scenario Based on median probability and severity Risk Severity Cost Range Occurrence Likelihood of Median Median Most Likely ID Rating ( 000 s) rating occurrence (%) Probability Severity Cost Scenario Details of Financial Provision/Insurance Galway County Council is currently reviewing their environmental liability pollution insurance cover in the Tuam agglomeration in light of this report.