LETTERKENNY AER 2013 Licence Register No. D0009-01 Table of Contents Contents 1.0 Executive Summary and Introduction to the 2013 AER 3 1.1 Summary Report on 2013 2.0 Monitoring Reports Summary 5 2.1 Summary Report on Monthly Influent Monitoring 5 2.2 Discharges from the Agglomeration 5 2.3 Ambient Monitoring Summary 6 2.4 Data collection and Reporting Requirements under the Waste Water Treatment Directive 7 2.5 Pollutant Release and Transfer Register (PRTR) Report for the Previous Year 7 3.0 Operational Reports Summary 7 3.1 Treatment Efficiency Report 7 3.2 Treatment Capacity Report 7 3.3 Extent of Agglomeration Summary Report 8 3.4 Complaints Summary 8 3.5 Reported Incidents Summary 8 3.6 Sludge/ Other Inputs to the WWTP 8 4.0 Infrastructural Assessments and Programme of Improvements 9 4.1 Storm Water Overflow Identification and Inspection Report 9 4.2 Report on Progress Made and Proposals being Developed to meet the Improvement Programme Requirements 10 5.0 License Specific Reports 11 5.1 Priority Substances Report 11 5.2 Drinking Water Abstraction Point Risk Assessment 11 5.3 Shellfish Impact Assessment Report 11 5.4 Toxicity/Leachate Management 11 5.5 Toxicity of Final Effluent Report 11 5.6 Pearl Mussel Measures Report 12 5.7 Habitats Impact Assessment Report 12 6.0 Certification and Sign Off 13 7.0 Appendices 15 Appendix 1 Schematics of Letterkenny Wastewater Treatment Plant & Sludge Treatment Centre 15 Appendix 2 Influent Monitoring Results 17 Appendix 3 Effluent Monitoring Analysis with Schedule A Emission Limit Values 18 Appendix 4 Ambient Monitoring Results 19 Appendix 5 PE Calculation/Analysis 20 Appendix 6 Efficiency Analysis 21 Appendix 7 Pollutant Release Transfer Register (PRTR) 22 Appendix 8 Unsewered Area Within Letterkenny Agglomeration 28 Appendix 9 Urban Waste Water Treatment Plant Returns 2013 29 2 1.0 Executive Summary and Introduction to the 2013 AER 1.1 Summary Report on 2013 Letterkenny Wastewater Treatment Plant and Sludge Treatment Centre were officially opened on the 8 th November 2013. Construction works commenced on the new treatment plant and sludge centre in May 2011 with Donegal County Council handing over the daily operation and maintenance of the old treatment plant to the contractor engaged to carry out the work, Severn Trent Water/Response Engineering in June 2011. While the Design & Build element of the contract was scheduled to be completed by March 2013, the new treatment works came into operation in October 2012 with the emission limit values for the various parameters set out in Schedule A of the Wastewater Discharge Licence being complied with fully since then. Under the Design, Build, Operate contract, Severn Trent Response will operate and maintain the wastewater and sludge treatment plants for a 20 year period. The agglomeration of Letterkenny comprises of a combined collection system, much of it in existence since the 1950s and 1960s. Many of the more recent areas of residential development are served by partially separated collection systems. Significant improvements were carried out on the sewer network during 2004 and 2005, including the installation of new trunk pipeline, the construction of a number of sewage pumping stations and the decommissioning of two major storm water overflows. Further upgrade works to improve the network and address the discharges to be discontinued listed in Schedule A.3 of the licence are at detailed design stage. Some outline data on the new Letterkenny Wastewater Treatment Plant and Sludge Treatment Centre is listed below while a schematic of the plant included in Appendix 1. Stormwater Site • Storm Overflow system allows max 300l/s flow for treatment ; • Excess storm flows to storm holding tank cap. 3,450 m3; • Stored wastewater is pumped back for full treatment later; • Allows discharge to River Swilly in exceptional circumstances if the tank is full and the storm continues. Wastewater Treatment Works • Stage 1 design capacity 40,000 population equivalent, 312 l/s: Provision to double the capacity in stage 2; • Treatment units include • Inlet works : screening, grit & grease removal; • Biological treatment: twin aeration chambers including P- removal; • Clarifiers: settlement & remove scum & sludge; • UV disinfection; • Odour treatment 3 Sludge Treatment Centre • Design capacity to treat 2,500 tonnes of dry solids annually. • Sludge is dried to 90% dry solid pellets and used as fertiliser on land • Facilities include • Reception of leachate, liquid & cake sludges; (leachate and waterworks sludges sent to WWTW for full treatment) • Wastewater liquid sludge is de-watered and mixed with cake; • (Anaerobic digestion & electricity generation); • Sludge drying • Odour treatment • Wastewater pumping station to serve south Letterkenny in the future when a wastewater collection network is developed. The Wastewater Discharge Licence for the agglomeration of Letterkenny was issued by the Environmental Protection Agency in March 2010 and this is the 4 th Annual Environmental Report. There were no exceedences of the Emission Limit Values (ELVs) for the following parameters listed in Schedule A of the discharge licence in 2013: • Temperature • pH • cBOD • COB • Suspended Solids, • Total Oxidised Nitrogen (as N) • Ammonia (as N) • Ortho-Phosphorus (as P) This represents a significant improvement in the quality of effluent entering the receiving waters since the granting of the wastewater discharge licence. In 2013, the treatment capacity of the plant was greater than the hydraulic and organic loading entering same. The average PE for the treatment plant in 2013 was 18,400. Results from the many analyses are attached in the Appendices at the end of this report with summary tables contained in the body of the document. The discontinuation of the discharges from the stormwater overflows listed in Schedule A3 of the licence is included in The Letterkenny Sewerage Improvement Scheme, Phase 3. It is expected that this project will go to tender in 2014, depending on the approval of Irish Water and the availability of funding. 4 2.0 Monitoring Reports Summary 2.1 Summary Report on Monthly Influent Monitoring Appendix 2 contains a table presenting results of monthly influent analysis as required in Condition 4.16 of the licence. These can be summarised as follows: - BOD COD SS (mg/l) Total P Total Hydraulic Organic (mg/l) (mg/l) (mg/l) N loading Loading (mg/l) (m 3/day) (PE/day) No. of 12 12 12 12 12 Samples Annual Max 191.6 546 249 5.61 48.1 27,673 37,174 Annual 110.9 345.25 173.92 3.27 23.97 10,004 15,975 Mean While the maximum daily hydraulic loading recorded was 27,673 m3/day on the 31 st January 2013 , this figure is still less than the hydraulic capacity of the treatment works which stands at 32,400 m3/day. This figure was exceptional and over twice the average for the year. It coincided with the highest recorded BOD for the year, which was more than twice the average. 2.2 Discharges from the Agglomeration Appendix 3 contains a table presenting results of monthly effluent analysis as required in the licence. These can be summarised as follows: - Temp. pH BOD COD SS Amon Total Total P (mg/l) (mg/l) (mg/l) (mg/l) N(mg/l) (mg/l) WWDL ELV 25 ◦C 6–9 25 125 35 5 15 1* (Schedule A) (max) ELV with 25 ◦C 6–9 50 250 70 5 15 1* Condition 2 (max) Interpretation Number of 12 12 12 12 12 12 12 12 Samples Number of 0 0 0 0 0 0 0 0 Samples above WWDL ELV Number above 0 0 0 0 0 0 0 0 ELV with Cond 2 Interpretaton Annual Mean ( n/a n/a n/a n/a n/a n/a n/a n/a Where Mean ELV applies) Overall Pass Pass Pass Pass Pass Pass Pass Pass Compliance (Pass/Fail) Emissions Limit Value of 1 applicable from 21 st December 2012, value of 2 applied prior to this date. 5 There were no exceedences of the emission limit values listed in Schedule A on the licence in 2013 which demonstrates that the plant was able to deal comfortably with the hydraulic and organic loading entering the treatment works in 2013. 2.3 Ambient Monitoring Summary In compliance with the requirements of Conditions 4.17 and 4.18 of the Waste Water Discharge Licence and in accordance with Schedule B4, a summary of the ambient monitoring results for 2013 is tabulated below. UPSTREAM DOWNSTREAM Range Average Range Average pH 6.84 – 8.32 7.87 6.72 – 8.32 7.77 DO 11.04 – 13.38 12.10 10.27 – 13.16 11.97 BOD 0.43 – 6.70 3.72 0.42 – 7.24 3.77 MRP (Ortho P) 0.015 – 0.048 0.027 <0.01 – 0.076 0.029 Total Nitrogen 0.5 – <10 3.007 0.50 – <10 3.12 Ammonia (as N) 0.042 – 0.186 0.092 <0.01 – 0.216 0.124 DIN 0.07 – 0.267 0.181 0.014 – 0.896 0.292 Chlorophyll 3.16 – 37.71 25.7 1.95 – 48.55 27.29 The location of the discharge point in conjunction with tidal constraints means that ambient monitoring can only take place at high tide. Accordingly, it is possible that the upstream and downstream results can vary depending on whether the tide is ebbing or flowing. Nevertheless, an examination of the results reveals that the discharge is not having a negative impact on the receiving water. Appendix 4 of this report presents the results of the ambient monitoring taken upstream and downstream of the discharge point in 2013. Details of the locations of the ambient monitoring points are listed below.