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5.0 WATER 5.1 Introduction

This section describes the baseline water environment and also discusses the constraints and opportunities posed by the water environment of Bay.

The proposed S2S route essentially runs along the coastline of from Sutton to Sandycove. Dublin Bay is a unique water environment, with its miles of sandy beaches and swimming areas in the heart of the city. Dublin Bay is the city’s finest amenity and Dublin also is the location of the largest shipping port in Ireland. Over a million Dubliners enjoy Dublin Bay. They look out on it, walk along the promenades and shores, play on the beaches, swim, sail, fish and windsurf.

The bathing water quality of Dublin Bay has greatly improved over the last few years as a result of the construction of an advanced wastewater treatment plant in Ringsend in 1999. Prior to this, wastewater from Dublin was pumped to the Ringsend Treatment Works where it received primary treatment only before being discharged into the bay and wastewater from the north of the city was discharged, untreated, into the sea at Howth.

The EPA produces an annual report which presents key findings and results for 2003 on the quality of Ireland's bathing waters. The EPA Bathing Water Report for 2003 7 shows that the water quality at Dollymount Strand and Merrion Strand improved between 2002 and 2003 and was fully compliant with the mandatory and guide values of the EU bathing water quality requirements. In addition, early in 2004, Seapoint beach was designated as a Blue Flag Beach, which requires a high standard of water quality to be maintained.

The legislation governing the water quality of Dublin Bay is discussed in the following section.

5.1.1 Legislation Governing Water Quality

EU Water Quality Directives and Associated Regulations There is a large body of legislation governing the water quality of Dublin Bay There are several primary EU Directives, which are particularly relevant to the quality of water for various uses which have been adopted by the European Union. National Regulations have been made in connection with these Directives. The requirements of these Directives are summarized in the following paragraphs.

Bathing Water Directive (76/160/EEC) The Bathing Water Directive has been given effect in Irish law by the European Communities (Quality of Bathing Water) (Revocation) Regulations, 1992. It is the primary legislation governing the quality of bathing waters. The purpose of the Directive is to ensure that the quality of bathing water is maintained and, where necessary, improved so that it complies with specified standards designed to protect public health and the environment. The National Limit Values set by the regulations and the European Mandatory and Guide Values are summarized in Appendix A – 5.1.

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Surface Water Directive (75/440/EEC) The Surface Water Directive covers the quality of surface water which is used a source of human consumption after the appropriate treatment processes. It has been given effect by the European Communities (Quality of Surface Water Intended for the Abstraction of Drinking Water) Regulations, 1989. The Regulations categorize surface waters from which water for public supply will be taken as A1, A2 or A3, depending on the (increasing) degree of treatment which will be applied and they set out quality standards.

Dangerous Substances Directive (76/464/EEC) The Dangerous Substances Directive on pollution caused by certain dangerous substances discharged into the aquatic environment of the Community was one of the first water related Directives to be adopted. It has objective of regulating potential aquatic pollution by thousands of chemicals. The Directive covers discharges to inland surface waters, territorial waters, inland coastal waters.

Freshwater Fish Directive (78/659/EEC) The Freshwater Fish Directive was introduced in 1978. It was incorporated into Irish law in 1988 when the Minister for the Environment signed the European Communities (Quality of Salmonid Waters) Regulations, 1988 (Statutory Instrument S.I No. 293 of 1988). This directive is very important because its sets quality standards for fresh water. Fresh water fish can only live in high quality, clean fresh water. If the water quality standards for fish (particularly salmonid fish) are met then the water will be of sufficiently high quality for a variety of beneficial uses as already outlined, for example serving as a source of drinking water and the support of wildlife.

Shellfish (79/923/EEC) The Directive concerns the quality of shellfish waters and applies to coastal and brackish waters designated as needing protection or improvement in order to support shellfish.

Groundwater (80/68/EEC) The Groundwater Directive aims generally at protecting groundwater by preventing the discharge into groundwater of certain substances (specified in List 1 in the Annex to the Directive) and by limiting the discharge of certain other substances (specified in List 2 of that Annex).

Drinking Water Directive (80/778/EEC) (98/83/EC) The basic standards governing the quality of drinking water intended for human consumption are set out in EU Directive 98/83/EC. These Regulations came into force in January 2004 (when they revoked and replaced EC (Quality of Water intended for Human Consumption) Regulations, 1988 as amended.

All water for human consumption, whether in its original state or after treatment, regardless of origin is covered by Directive 98/83/EC The Regulations specify standards in respect of 48 parametric values which are grouped into three categories, i.e. microbiological, chemical and indicator parameters. More stringent standards will be introduced for Lead, Ammonium and Fluoride.

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Urban Waste Water Treatment (91/271/EEC) The Urban Wastewater Treatment Directive addresses nutrient-based, bacterial and viral pollution caused by urban wastewater. The Directive requires that urban centres (cities, towns and settlements) meet minimum wastewater collection and treatment standards within deadlines fixed by the Directive. These deadlines are fixed according to the sensitivity of the affected waters and to the size of the urban population concerned.

The Irish Government aim to meet the EU Urban Waste Water Treatment Directive in relation to provision of secondary treatment in urban areas by the end of 2005. This aspect has been the main focus of investment under the Wastewater Services Investment Program (WSIP) over the past number of years. At the start of the current National Development Plan period in 2000, compliance with the Directive stood at 25%. Following the completion of the Ringsend wastewater treatment plan for the Dublin region earlier this year, this has now risen to 69% and is expected to increase further to 87% by the end of the year. It is expected that Ireland will have achieved full compliance by the end of 2005.

Nitrates (91/676/EEC) The Nitrates Directive has the objective of reducing water pollution caused or induced by nitrates from agricultural sources and preventing further such pollution. It is intended both to safeguard groundwater and to prevent wider ecological damage in the form of eutrophication of freshwater and marine waters generally.

With the exception of the Dangerous Substances and Groundwater Directives, all of the above directives are based on the “Environmental Quality Objective” (EQO) approach, in which standards are laid down for various types of water in which contaminants may be found, and the concentrations of which are limited.

Water Framework Directive Most of these individual Directives give way to the Water Framework Directive (200/60/EC), which addresses inland surface waters, estuarine, and coastal waters and groundwater. The Water Framework Directive was adopted into Irish Law in December 2003 and provides a comprehensive framework for water quality management across the EU. It requires that we take a holistic view of water and how it sustains life. The fundamental objective of the Water Framework Directive aims at maintaining ‘high status’ of waters where it exists, preventing the deterioration in the existing status of waters and achieving at least “good status” in relation to all waters by 2015. 

5.2 Methodology

The Geological Survey of Ireland (GSI) well card and groundwater records for the area were inspected, with reference to hydrology and hydrogeology 3.

Site visits were carried out in June - August 2004, by AWN Consulting Ltd in order to assess the water environment along the route of the S2S.

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5.3 Baseline Environment

5.3.1 Surface Water Quality and Environment The route follows the coastline of Dublin Bay from Sutton to Sandycove.

During the site visits, carried out by AWN Consulting, it was determined that there were a number of watercourses that the proposed S2S route will cross for which there is currently insufficient existing baseline water quality data available. It was also felt that insufficient data was available on the quality of coastal waters at certain points. Water samples were collected and analysed on site and in a laboratory for a range of physiochemical parameters to determine the baseline water quality at these locations. Water samples were collected from Sandymount Strand, Elm Park Stream, Booterstown outfall and Seapoint along South Dublin Bay and from the and Sutton Creek along North Dublin Bay. The results for the on site and laboratory analysis can be seen in Table 5.1. Table 5.2 shows the AWN sampling locations.

Figures 5.1 – 5.5 illustrates AWN’s sampling locations and the hydrological environment along the S2S route.

Sample No. Parameter Units123 4 5 6 Temperature Deg. C 22.2 21 22 21.2 21.1 20.8 pH pH units 8.23 7.87 8.17 8.1 8.61 8.24 Oxygen saturation % 100 110 120 105 125 97 Dissolved Oxygen mg/l 8.5 9.6 10.3 9.3 11.02 8.4 Conductivity mS/cm 51.2 2.76 52.1 53 46.5 47.9 BOD mg/l 2 <2 <2 <2 3 3 Suspended Solids mg/l 208 34 50 184 28 286 Total Oxidised Nitrogen mg/l 0.5 0.7 <0.3 <0.3 <0.3 <0.3 Sulphate mg/l 2638 101 2652 2723 2327 2499 Orthophosphate mg/l 0.26 0.1 0.12 0.07 0.29 0.48

Table 5.1 AWN water monitoring results – August 2004

Sample No. Location 1 Sandymount Strand (sea) 2 Elm Park Stream 3 Booterstown Outfall 4 Seapoint (sea) 5 Naniken River 6 Sutton Creek

Table 5.2 AWN sampling locations – August 2004

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Figure 5.1 Surface Water Monitoring Location S01

Figure 5.2 Surface Water Monitoring Locations S02 and S03

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Figure 5.3 Surface Water Monitoring Location S04

Figure 5.4 Surface Water Monitoring Location S05

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Figure 5.5 Surface Water Monitoring Location S06

The water monitoring results for the sea, rivers and streams along the proposed S2S route are compared with the National Limit Values set by the Bathing Water Regulations and the European Mandatory and Guide Values set by the Bathing Water Directive (Appendix A – 5.1) (where limit values have been set) to assess the baseline water quality. Where, limit values have not been set by the Bathing Water Directive and National Limits for certain parameters, the results will be compared with the EU and Irish Surface Water Limits which classifies water bodies as A1, A2 and A3 8 waters (Appendix A - 5.2).

The Environmental Protection Agency (EPA) use Q Values to express the biological water quality, based on changes in the macro invertebrate communities of riffle areas brought about by organic pollution. Q1 indicates a seriously polluted water body; Q5 indicates unpolluted water of high quality. Table 5.3 explains the terminology used for the Q Values. The key to the Q- ratings in included in Appendix A – 5.4. The existing water quality data available from the EPA expresses the biological water quality as Q Values.

Quality Quality Pollution Status Condition Ratings Class Q5, Q4-5, Q4 Class A Unpolluted Satisfactory Q3-4 Class B Slightly Polluted Unsatisfactory Q3, Q2-3 Class C Moderately Polluted Unsatisfactory Q2, Q1-2, Q1 Class D Seriously Polluted Unsatisfactory

Table 5.3 EPA Biological Q Ratings

Existing water quality monitoring data was obtained from the Central Laboratory at and the EPA Water Quality database 2.The

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water quality of the coastal waters and watercourses that will be crossed by the proposed route will be discussed for each watercourse and coastal water monitoring location along the route from the northern boundary of the route, at Sutton to Sandycove.

Sutton to North Causeway Sutton Creek is an intertidal lagoon, which spans the coastline from Sutton, the northern boundary of the S2S route, to the North Bull Island causeway. At low tide the lagoon is drained to expose extensive mud and sand flats. There is a permanent channel flowing through the lagoon, this is the River , which flows in a north easterly direction into the lagoon. The Blackbanks and Kilbarrack Stream also feed the lagoon. The and a surface water outfall enter Sutton Creek at the Bull Island causeway through 2 no. adjacent concrete culverts. The Blackbanks Stream enters Sutton Creek through a concrete culvert adjacent to the junction of the Howth Road and James Larkin Road. There is an existing promenade, which varies in width from 3 to 6m that runs along the seawall from Sutton to the Bull Island Causeway. It is proposed to extend this promenade with a pier or cantilever structure. The extension of the promenade will necessitate crossing Sutton Creek and the Blackbanks and Kilbarrack stream outfalls. There is existing water quality data available for the Santry River and the Blackbanks and Kilbarrack Streams from Dublin City Council. In addition, a water sample was collected from Sutton Creek in order to assess the baseline quality of the lagoon. The existing water quality data for the Santry River, was recorded during the period 1998 – 2000 and is reported in the Water Quality in Ireland publication by the EPA, 2002 10. This data provides a comprehensive picture of the existing river quality. Table 5.4 below shows the Q values for the Santry River (Table 5.3 above explains the terminology used in Table 5.4).

Sampling Stations Biological Quality Ratings (Q Values)

No. Location 1988 1989 1990 1991 1994 1996 1998

0300 Clonshaugh Rd Br 1112/01/021-2 1100 Bettyglen 1 1 1 2-3 1-2 2-3/0 2/0

Table 5.4 EPA Biological Quality (Q) ratings for the Santry River

The closest sample location to S2S where a Q value has been recorded on the Santry River is at Bettyglen, just upstream from where the Santry River discharges into Sutton Creek. The Q rating for the Santry River shows the river water quality to be very poor, with Q values of 1 – 2, indicating serious pollution.

The chemical analysis carried out by Dublin Corporation during the same period shows the water quality of the river to be poor-medium. Whilst oxygen saturation is moderate, there are high levels of nutrients and BOD in the water. The physiochemical data is presented in Table 5.5 below. Table 5.6 details the locations of the monitoring stations.

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The current E.U and Irish legislation limits for surface water bodies are shown in Appendix A - 5.1. The Santry River falls into the A3 category under the Surface Water Regulations.

Station pH Conductivity Temperature No. μS cm-1 oC No. Min Med Max No. Min Med Max No. Min Med Max 0300 20 7.7 8.0 8.4 20 422 749 873 19 5.0 10.5 18.0 0500 12 7.8 8.1 8.2 12 418 794 889 11 4.6 9.1 15.2 0700 28 7.8 8.2 9.0 28 215 734 864 27 4.8 10.9 17.4 0880 18 7.7 8.5 9.2 18 173 737 1111 18 6.8 13.8 17.9 1100 28 7.3 8.2 8.8 28 233 713 861 28 7.0 12.4 18.0

Station Dissolved Oxygen Dissolved Oxygen B.O.D -1 -1 No. % Saturation mg O21 mg O21 No. Min Med Max No. Min Med Max No. Min Med Max 0300 12 73 96 123 12 7.4 10.8 14.2 - --- 0500 10 78 96 118 10 7.8 11.1 14.9 - --- 0700 10 84 105 139 10 10.0 12.2 15.0 6 3.0 4.5 8.0 0880 ------5 3.0 5.0 7.0 1100 5 71 94 97 5 7.4 10.6 11.0 5 2.0 4.0 5.0

Station Total Ammonia Un-Ionised Ammonia -1 -1 No. mg N 1 mg NH3 1 No. Min Med Max No. Min Med Max 0300 11 0.05 0.08 0.61 8 0.001 0.002 0.017 0500 6 0.05 0.10 0.30 5 0.001 0.003 0.007 0700 17 0.03 0.08 0.33 16 0.002 0.005 0.008 0880 9 0.02 0.09 0.25 9 0.002 0.007 0.023 1100 17 0.02 0.08 0.70 15 <0.001 0.003 0.019

 Station Oxidised Nitrogen Ortho-Phosphate -1 -1  No. mg N 1 mg P 1  No. Min Med Max No. Min Med Max  0300 10 1.2 2.4 4.2 16 0.03 0.05 0.13  0500 6 1.0 2.0 4.1 7 0.05 0.06 0.10  0700 16 0.6 2.0 4.3 18 0.05 0.13 0.26  0880 12 0.8 2.7 4.3 13 0.06 0.14 0.29  1100 18 0.8 2.4 4.3 24 0.05 0.13 0.29   A bold-faced value indicates that the value is either greater than an upper threshold level or less than a lower threshold value for individual parameters. These threshold values are given in Appendix A – 5.3. These are not legal limits but are intended to highlight stations where there may be water quality problems.

Table 5.5 Dublin Corporation Chemical Analyses of the Santry River 1998 - 2000

Sampling Stations Location No.

0300 Clonshaugh Rd Br 0500 Br on Drive 0700 Br on Tonlegee Rd 0880 0.2 km u/s Howth Rd Br 1100 Bettyglen

Table 5.6 Dublin City Council Water Quality Monitoring Location for the Santry River

Dublin City Council monitors the Blackbanks Stream (Table 5.7) and the Kilbarrack Stream (Table 5.8) as part of the Dublin Bay Project. Monitoring

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data for June and July 2004 shows the water quality of the stream to be poor with high numbers of Total Coliforms and Escherichia coli (E.Coli).The Blackbanks and Kilbarrack Streams exceed the mandatory limit set by the EU Bathing Water Directive for Total Coliforms (Appendix A – 5.1).

Sample Units June 2004 July 2004 pH pH units 8 7.85 Cond 20 μS/cm 1245.5 619

BOD_ATU mgO2/l - -

COD mgO2/l 27 112 Nitrate as N mgN/l - - Nitrite as N mgN/l - - Ammonia as N mgN/l - - Rct_PhosP mgP/l - - Total Oxidised Nitrogen mgN/l - - Suspended Solids mg/l - 28 Total Coliforms MPN/100ml 27720 - E. Coli MPN/100ml 4215 1850

Table 5.7 Dublin City Council Water Quality Monitoring Data for the Blackbanks Stream – Averages for June and July 2004

Parameter Units June 2004 July 2004 pH pH units 7.9 7.91 Cond 20 μS/cm 1305 1014.83

BOD_ATU mgO2/l - 3.5

COD mgO2/l 39 133.14 Nitrate as N mg N/l - 1.75 Nitrite as N mg N/l - 0.10 Ammonia as N mg N/l - 0.45 Rct_PhosP mg P/l - 0.14 Total Oxidised Nitrogen mg N/l - 1.85 Suspended Solids mg/l 13 13 Total Coliforms MPN/100ml 86025 53745 E. Coli MPN/100ml 18695 2974

Table 5.8 Dublin City Council Water Quality Monitoring Data for the Kilbarrack Stream – Averages for June and July 2004

The water sample collected from Sutton Creek during high tide shows that the pH and dissolved oxygen meet the Bathing Water Directive mandatory limits and the Bathing Water Regulations National Limit Values (Appendix A – 5.1). The water sampling location is shown in Figure 5.5. Conductivity and sulphate are high (above Surface Water Regulatory Limits) but this is to be expected in seawater. The Bathing Water Regulations and Directives do not set limit values for conductivity and sulphate concentrations for bathing waters.

With regard to the current E.U and Irish legislation limits for surface water bodies (Appendix A - 5.1), Sutton Creek exceeds the surface water limits under the Surface Water Regulations for orthophosphate and suspended

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solids but has a high dissolved oxygen content and a low BOD value. The water quality of Sutton Creek is moderate to poor, which is consistent with the water quality of the Santry River and the Blackbanks and Kilbarrack Streams, which feed the creek.

North Bull Island Causeway to Irishtown South of the Bull Island causeway, an intertidal lagoon is fed by the Naniken River, which forms a permanent channel through the lagoon. The Naniken River flows in a southwest direction under the Bull Bridge, which joins Bull Island and the mainland. The proposed route will cross the Naniken River by a pier structure. During the site visit, a water sample was collected from the Naniken River (Table 5.1). The sampling location is shown in Figure 5.8. The results of the on-site and laboratory analysis show the water quality of the Naniken River to moderate to good quality. The suspended solids, BOD, dissolved oxygen and pH levels are within the surface water limits (Appendix A – 5.2). However, the orthophosphate concentration was below the surface water limit values.

Monthly water quality monitoring was also carried out on the Naniken River (at St. Anne’s Park, along the Clontarf Road) by Dublin City Council for the period 2000 to 2004 as part of the Dublin Bay Project. Table 5.9 summarises the average values for each year. Monitoring data for 2000 - 2004 shows the water quality of the Naniken River to be of moderate quality and it appears to have improved over the last few years. The pH and oxygen saturation meet the Bathing Water Regulations National Limit Values (Appendix A – 5.1). The Naniken River falls into A3 category under the Surface Water Regulations (Appendix A – 5.2)

Parameter Units 2000 2001 2002 2003 2004 Temperature °C 11.30 11.48 12.53 11.08 10.90 pH pH units 7.95 8.11 7.94 8.02 8.02 Cond 25°C μS/cm 658.50 551.08 486.75 529.79 585.00 Cond 20°C μS/cm - - - - 435.33 Total Nitrogen mg N/l - 3.12 3.62 3.54 3.18 Total Phosphorus mg P/l 0.14 0.23 0.25 0.10 0.17

BOD_ATU mgO2/l - 7.33 2.00 5.20 6.00

COD mgO2/l 12.00 21.14 23.75 17.17 12.25 Nitrate as N mg N/l 4.34 2.92 2.57 2.78 2.68 Nitrite as N mg N/l 0.05 0.05 0.05 0.04 0.04 Ammonia as N mg N/l 0.06 0.20 0.34 0.33 0.09 Rct_PhosP mg P/l 0.09 0.18 0.19 0.09 0.14 Total Oxidised Nitrogen mg N/l 4.29 3.00 2.62 2.82 2.72 Oxygen Saturation %Sat 93.40 94.95 91.08 93.50 96.24 Dissolved Oxygen mg/l - 9.75 9.47 10.32 10.70

Suspended Solids mg/l 10.00 39.00 49.25 16.50 10.00

Table 5.9 Dublin City Council Water Quality Data for the Naniken River for the period 2000 – 2004 (Average values were calculated from monthly water quality monitoring data).

The Tolka River flows into the Tolka Estuary at the John Mc Cormick Bridge in . It is proposed that the S2S will cross the John Mc Cormick Bridge

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over the Tolka River. The Tolka Estuary is an intertidal area with extensive areas of sandy flats. It is a wetland of international importance and is part of the Sandymount Strand/Tolka Estuary Special Protection Area (SPA).

The EPA has been carrying out biological monitoring on the for the last 30 years, and also physiochemical monitoring for the past number of years. The most recent biological monitoring data available is for the period 1988 – 1998 (Table 5.10). The biological quality rating (Q value) of the Tolka River at the closest monitoring location to the S2S route (Drumcondra Road Bridge) was 2-3 in 1998, which indicates the river is moderately to seriously pollutedinthisarea.

Sampling Station No. Location Biological Quality Rating (Q) 1988 1989 1990 1991 1994 1996 1998 0800 Br 2 2-3 - 2-3 3 2-3 3 0900 Br u/s 23-33- - 1000 Abbotstown Br 2-3 3 - 2-3 - 3 2-3 1050 Cardiff's Br 33-33- - 1100 Violet Hill Drive 1-2 1-2 1 1/0 2-3/0 3 2-3 1200 Drumcondra Rd Br 21/01-222-3- -

Table 5.10 EPA Biological Quality (Q) ratings for the Tolka River

Monthly water quality monitoring carried out on the Tolka River by Dublin City Council from 1999 to 2004 at Drumcondra Road Bridge also shows that the quality of the river is poor. Table 5.11 presents the average values for each year for the period 1999 to 2004. Total Coliforms are outside the EU Bathing Water Mandatory and the National Bathing Water Limit Values (”10,000 for 95% samples), (Appendix A – 5.1). Under the Surface Water Regulations the data presented in Table 5.11 below shows the Tolka River falls into the A3 category (Appendix A – 5.2).

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Parameter Units 1999 2000 2001 2002 2003 2004 Temperature °C 12.30 12.94 11.19 11.69 11.20 7.37 pH pH units 8.29 8.26 8.22 8.21 8.24 8.20 Conductivity μS/cm 696.13 945.90 750.17 714.31 712.60 761.33

BOD mgO2/l 2.50 - - - - -

BOD_ATU mgO2/l - 3.75 4.17 2.57 2.25 3.00 COD 22.75 18.40 20.83 19.08 16.85 16.67 Nitrate as N mg N/l 2.49 2.23 2.36 2.38 2.50 3.67 Nitrite as N mg N/l 0.05 0.06 0.07 0.06 0.06 0.05 Ammonia as N mg N/l 0.20 0.26 0.53 0.11 0.29 0.32 Rct_PhosP mg P/l 0.14 0.13 0.11 0.11 0.07 0.10 Total Oxidised Nitrogen mg N/l 2.54 2.42 2.42 2.44 2.57 3.72 Oxygen Saturation % Sat - 93.75 95.76 101.22 102.53 100.77 Dissolved Oxygen mg/l - - 9.97 10.79 11.39 12.14 Suspended Solids Mg/l 30.00 20.50 39.86 43.92 28.31 36.67 Total Coliforms MPN/100ml - - - - 17961.75 - Pr.F.Coli MPN/100ml 2808.75 4960.00 5733.33 2071.43 - - E. Coli MPN/100ml - - - - 1594.20 10462.00

Table 5.11 Dublin City Council Water Quality Data for the Tolka River (at Drumcondra Road Bridge for the period 1999 – 2004 (Average values were calculated from monthly water quality monitoring data).

The rises between the mountains of Kippure and Tonduff in County Wicklow and flows for a distance of around 120 km before reaching the sea in Dublin Bay. The water quality of the River Liffey is monitored continuously by the Dublin City Council. The most recent water quality data available the for River Liffey is for 1999 – 2004. The closest monitoring location on the River Liffey to the S2S route is the Islandbridge Weir. The water monitoring data presented in Table 5.12 below for the Islandbridge Weir, indicates that the quality of water of the River Liffey is moderate to poor at this location.

The Total Coliforms exceed the mandatory EU bathing water limits and the National Bathing Water Limit Values in 2003 and 2004 (Appendix A – 5.1). However, based on the data presented in Table 5.12 below, the Tolka River falls into the A3 category under the Surface Water Regulations (Appendix A – 5.2).

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Parameters Units 1999 2000 2001 2002 2003 2004 Temp oC 10.28 13.15 12.14 13.36 10.11 5.80 pH pH units 8.17 8.16 8.32 8.28 8.19 8.10 Cond μS/cm 550.78 548.36 514.55 517.12 494.24 482.00

BOD mgO2/l 2.50 - - - - -

BOD_ATU mgO2/l 3.00 2.67 3.09 3.25 2.00 -

COD mgO2/l 15.14 16.09 16.00 16.29 14.21 16.33 Nitrate as N mg N/l 2.28 1.82 1.96 1.85 2.21 2.89 Nitrite as N mg N/l 0.05 0.03 0.04 0.04 0.03 0.02 Ammonia as N mg N/l 0.10 0.05 0.06 0.06 0.11 0.09 Rct_PhosP 0.16 0.15 0.08 0.05 0.04 0.05 Total Oxidised Nitrogen mg N/l 2.32 1.94 2.00 1.89 2.24 2.04 Oxygen Saturation %Sat - 93.83 104.11 107.43 108.04 106.52 Dissolved Oxygen mg/l - - 11.58 18.66 12.09 14.11 Suspended Solids mg/l 10.89 10.55 11.90 11.76 10.71 11.46 Total Coliforms MPN/100ml - - - - 14560.33 14560.33 Pr.F Coli MPN/100ml 3767.50 3657.50 2150.00 2951.43 - 2550.71 E. coli MPN/100ml 1068.00 1068.00

Table 5.12 Dublin City Council Water Quality Data for the River Liffey at the Islandbridge Weir for the period 1999 – 2004 (Average values were calculated from monthly water quality monitoring data).

Irishtown to Booterstown Sandymount Strand is part of the Sandymount Strand/Tolka Estuary SPA. A water sample was collected from the sea at Sandymount Strand during the site visit at high tide. The analysis of this sample is presented in Table 5.1. The oxygen saturation level meets the Guide Values of the EU Bathing Water Directive and the National Limit Value for Bathing Water. pH is within the range of the mandatory and National Limit Values for bathing water (Appendix A–5.1).

Under the Surface Water Regulations, suspended solids and ortho-phosphate measured in the sample collected from the sea at Sandymount are above the limits values. The BOD concentration was below the limit value. The conductivity and sulphate concentrations were extremely high. However, this is to be expected due to the high salt content of coastal waters.

The EPA Bathing Water Report for 2003 7 showed that Sandymount failed to meet the National Standard Limit for bathing water quality for faecal streptococci during 2003. Faecal Coliforms originate in human and animal waste. Their presence is evidence that faecal contamination has occurred and a definite indication of the risk that pathogens may have been present in the sea at Sandymount 8.

Elm Park Stream, which flows through the Elm Park golf course, enters the sea at Merrion Strand, south of Merrion Gates. The Elm Park Stream outflow becomes silted up on occasion and has to be cleared by the Council. A

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sample was taken from this outflow during the site visit and the results are presented in Table 5.1. The oxygen saturation levels were within the Bathing Water Directive Guide Value range and the National Limit Value range. The pH measured was within the Mandatory EU and National Limit Values for bathing waters. BOD was below the limit of detection, oxygen saturation was high and suspended solids and sulphate levels were below the limit values. However, the ortho Phosphate measured was above the limits specified by the Surface Water Regulations. Based on the water sample collected, the water quality of Elm Park Stream appears to moderate-good. The EPA Bathing Water Report for 2003 7 shows that the water quality at Merrion Strand improved between 2002 and 2003 and was fully compliant with the mandatory and guide values of the EU bathing water quality requirements during this period.

St. Helens/Trimonstown Stream enters the bay at the northwestern end of Booterstown Marsh. This stream does not feed the marsh, but there is an over flow structure for times of high rainfall into the marsh. This culverted stream is a high concrete structure at the western side of the marsh. There was no existing baseline data available for this stream.

Booterstown Marsh Booterstown Marsh occurs to the landward side of Booterstown DART station. It is the only brackish marsh between Greystones and Dublin. The marsh was formed when the Dublin to Kingstown Railway cut across a small inlet between Blackrock and Merion in 1834. The marsh is under the influence of the sea. The sluice gates were opened in 1998, to allow sea water ingress and Dun Laoghaire Rathdown County Council removed flap valves from the marsh outflow in 2001, to allow much more tidal flow in the marsh. This has reduced algal formation and improved the water quality and may be reversing anoxic conditions in the sediments. However, there is freshwater coming in via the Nutley Stream.

The Nutley Stream feeds Booterstown Marsh and flows beneath the culverted St. Helens Stream and along the seaward side of the marsh. The outflow enters the bay southeast of Booterstown Station. This outflow becomes silted up approximately once a year and has to be cleared by the Council.

A water sample was collected at the outflow of the marsh during the site visit. The results of the on-site and laboratory analysis are shown in Table 5.1. The water quality of the marsh is moderate. The suspended solids, oxygen saturation, BOD and pH were within the limits of the Surface Water Regulations for A1 waters. The conductivity and sulphate concentrations were extremely high. However, this is to be expected due to the influence of the sea on the marsh.

Booterstown to Sandycove The Priory Stream enters Dublin Bay halfway along Blackrock Park. The stream used to enter the bay at the northwestern edge of Blackrock Park but it was redirected to this outfall. There was no baseline data available for this stream.

Carrysfort Stream enters the bay just northeast of Idrone Terrace. The stream is at a much lower level than the buildings near by. This stream is currently

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being hydrologically modeled by Dun Laoghaire Rathdown County Council as there has been flooding and backing up of the drainage upstream.

A water sample was collected from the sea south of Maretimo adjacent to Seapoint Terrace and Ardenza Terrace. The results of the analysis are shown in Table 5.1. The water quality of the sea at this location is moderate to good. The oxygen saturation levels measured were high and within the recommended range of the Guide and National limit values for bathing waters. As discussed in Section 5.1, Seapoint beach has recently been awarded the Blue Flag Award. Blue Flags are awarded on the basis of compliance with EU bathing water quality standards.

Monkstown Stream is culverted beneath the railways tracks, just south of the slipway at the start of the West Pier, Dun Laoghaire. There was no existing water quality available for this stream. However, the outfall of this stream is not located in close proximity to the proposed route of S2S.

Overall, it can be concluded that the water quality of the Bay appears to have improved, in recent years. This is as a result of the construction of the wastewater treatment plant in Ringsend. However, some the rivers and streams entering the bay are moderate to poor in quality such as the Santry River and the Blackbanks and Kilbarrack streams.

5.3.2 Drainage

Surface Water Drainage Surface water drainage emissions along the route that S2S is proposed to follow are restricted to run-off from hard standing areas, (car parks with an impermeable surface) after a rainfall event.

There are a number of surface water outfalls on the seaward side of the seawall along the proposed route which discharge to Dublin Bay. These outfalls drain surface water drains and gulleys in the vicinity of the route. The surface water outfalls along the S2S route are described in the following paragraphs.

A surface outfall enters Sutton Creek adjacent to the Blackbanks Stream outfall. A surface water drain which discharges to the creek is located along the seaward side of the sea wall across from Fox’s Lane on James Larkin Road. A large surface water outfall enters the creek through a concrete culvert adjacent to the Santry River outfall (at the Bull Island causeway).

There are also an additional 10 no. surface water outfalls, which enter the southern lagoon at the seawall between the Bull Island causeway and Bull Bridge. Along the section of the route between Bull Bridge and the Alfie Byrne Road, there are approximately 16 no. surface water outfalls, which enter the North Dublin Bay. There are 2 no. surface water outfalls that enter the Tolka Estuary along the proposed route. There are 2 no. surface water sewers that may also be crossed by the route on the section between the Alfie Byrne Road and East Wall Road.

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There is a surface water sewer, which runs along the edge of East Wall Road. There are also surface water pipes, which run down Church Road to Malachie Place. There are surface water sewers, which run down East Road. A surface water sewer runs for approximately 50m along North Wall Quay and joins the combined sewer system at the south end of New Wapping Road. There is a surface water sewage pipe approximately 25m long that runs across the East Link Toll Bridge roundabout on East Wall Road. There is a surface water sewer that runs from Church Avenue to the junction of Pembroke Road and the South Link Road. There is also a surface water pipe running from Sean Moore Park to Sandymount Strand. There is a surface water pipe flowing southeast from Sean Moore Park to the Sandymount Strand across from Marine Drive. There are 6 no. surface water outflows along the section of the strand across from Ailesbury Mews on the Strand Road. There is a surface water drain outfall just southeast of the Martello Tower, whichwillhavetobecrossedbytheroute. A surface water drain crosses the tracks from Dunleary Road just south of the West Pier. A surface water drain is culverted beneath the tracks just west of the harbour wall (across from Clarence St). This crosses back to the landward side of the tracks beneath the bridge/tunnel. The surface water drain will cross the S2S route at these two points, where the route passes under the tunnel alongside the train tracks. Any sections of the surface water drainage system underlying the proposed route that may be a constraint will be discussed in Section 5.4.

Foul Drainage There are trunk sewer and combined sewer pipes underlying sections of the proposed route.

A submarine pipeline, runs under the entrance to the existing cycle/pedestrian promenade where the Dublin Road meets the coastline (across from St. Fintans School). There are foul sewer pipes that underlie the Dublin Road from Sutton Cross to St. Fintan’s High School. There are 2 no. sewage pumping stations along the northern section of the route, one located adjacent to the junction of the Dublin Road and Baldoyle Road and the second one is at the Kilbarrack Road junction. Trunk sewers run along the promenade from Blackbanks to Sutton. A trunk sewer also runs across James Larkin Road from Fox’s Lane and across the existing promenade to the sea. There is a wastewater services hut along the proposed route, across from Dollymount House. There is a foul sewer pipe running along the Clontarf Road from approximately the halfway point between Dollymount Avenue and The Oaks. It runs along the seaward side of the road in the southwest direction to the wooden bridge. A foul sewer pipe runs along the wooden bridge from Bull Island and joins up to the foul sewer line that runs along the Clontarf Road. A combined sewer runs along the west side of Church Road until Seaview Avenue and then crosses to the east side of the road. Combined sewer pipes

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also run along the west side of Church Road from St. Mary’s Road North to Strangford Road. 3 no. combined sewer pipes run along Blythe Avenue and cross Church Road and Malachie Place. A combined sewer runs along East Wall Road from the junction with Church Road and also runs along East Road to the junction with Church Road. A combined sewer from the south end of New Wapping Road, runs up New Wapping Road, across Sheriff Street Upper and travels up East Road to Irvine Terrace. There is a sewage pumping station on East Road. A combined sewage pipe runs beneath the East Link Toll Bridge from East Wall Road and along York Road. There are 2 no. combined sewer pipes on York Road and a combined sewage pipe, which runs along Pembroke Cottages. There are also 2 no. combined sewage pipes at Cambridge Road, a trunk sewage pipe at the entrance to Ringsend Park and adjacent to the exit of Ringsend Park. There is a combined sewage pipe underlying Pembroke Street to the junction of Pembroke Street and the South Link Road. There is a trunk sewage pipe which Pembroke Street at the South Link Road junction. There are 2 no. combined sewage pipes on York Road and a combined sewage pipe runs along Thorncastle Road. At the junction of Thorncastle Street and Bridge Street, there are 2 no. pipes, a trunk sewer pipe and a combined sewer pipe, which run along Bridge Street to the junction with Caroline Row. Combined sewage pipes run along Irishtown Road. At the junction of Irishtown Road and Bath Street, there is a combined sewage pipe. There is combined sewage pipe, which runs along Bath Street to junction with South Link Road. Trunk sewer pipes run along the promenade at Sandymount from Booterstown to the navigation post at the northern end of the promenade where the trunk sewer pipe flows in a northeast direction to the Ringsend wastewater treatment plant. There is also foul sewer along Idrone Terrace, taking foul drainage in a southeast direction along the coastline on the landward side of the railway tracks. The foul sewer is piped over the Carrysfort Stream, as the stream channel is very deep at this point. From the sea wall along the front of Brighton Vale, there is a buried foul sewer running on the seaward side of the wall as far as house No. 3, before turning inland. One of the main Foul Drains for the area crosses beneath the railway tracks at approximately the start of Block 20 – 23 of the apartments at Salthill. It travels northeast towards the West Pier Pumping Station. Another foul sewer runs from east to west alongside the pathway between the back of the pumping station and the tracks. This is another main Foul Drain, which crosses to the seaward side of the tracks behind the Nautical College and runs east to west before being directed towards the West Pier pumping station. From Sandycove, a Foul Sewer runs east from Sandycove along Sandycove Avenue, close to the sea wall just beside the start of the park. This sewer runs behind the old clubhouse (landward side) before running along the coast. There is a concrete ledge along the front of the sea wall at the park, which is the culverted sewer. The sea has damaged it over the years. At the western side of the Sandymount Park this sewer meets a very large main foul drain

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and this again is part of the culvert all the way to the start of the grassy area along Scotsmans Bay.

Water Supply There are water supply pipes underlying various sections of the proposed route, along roads and footpaths.

5.3.3 Groundwater

Groundwater can be defined as water that is stored in, or moves through, pores and cracks in sub-soils. Aquifers are rocks or deposits that contain sufficient void spaces and which are permeable enough, to allow water to flow through them in significant quantities. The potential of rock to store and transport water is governed by permeability of which there are two types, intergranular and fissure permeability 3.

Intergranular permeability is found in sediments, sands, gravels and clays and fissure permeability is found in bedrock, where water moves through (and is stored in) cracks, fissures, planes and solution openings. The major aquifer underlying the route is a quaternary aquifer and therefore the primary characteristic of this aquifer is defined by intergranular permeability as opposed to fissure permeability, which would apply in the case of bedrock aquifer.

There are two dominant bedrock types underlying the proposed S2S route, limestone and granite. The changes in bedrock geology are fault controlled. A large fault, the Rathcoole Fault forms the southern margin of the Dublin Basin, where there is an unconformity between the granite and the limestone.

The section of the route from Sutton Cross to where the route meets the coast is comprised of muddy limestones, known as the Tober Coleen Formation, a mixture of calcareous shale and limestone conglomerate. The bedrock underlying the route from Sutton to Blackrock is Calp Limestone that consists of dark grey, fine-grained, graded limestone with interbedded black, poorly fossilised shales. A small wedge of bedrock, part of the Ballysteen Formation, separates the Calp Limestone and the Rathcoole Fault. The Ballysteen Formation is comprised of clean calcarenitic limestones. The Leinster Granite batholith underlies the route from Blackrock to Sandycove.

A report carried out on the hydrogeology and geology of Dublin shows the Calp limestone in the Dublin Basin has good permeability, suitable for domestic supplies, as permeability is higher near the surface 9. Therefore the limestone bedrock beneath the route is regarded as a minor aquifer. However, due to the proximity to the coast, water supplies would not be abstracted from this area, due to high saline content.

Granites in general have a low permeability. They are unimportant as aquifers although they are capable of yielding domestic supplies. However, higher permeability’s are present and larger quantities of water can be obtained along fault zones, pegmatite veins and in deeper weathered areas 9.

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The main feature which protects groundwater from contamination, and hence the most important feature in protection of groundwater, is the subsoil (which can consist solely of, or mixtures of, peat, sand, gravel, glacial till, clays or silts).

The subsoil underlying the South Dublin area is uniform in composition and consists of tills and gravels. The till may contain shells dredged from the . The substrate of the northern section of the Bay is predominantly sand overlying gravels and clay. The sand and gravel aquifers in the Dublin Bay area are classed as minor aquifers. In general the groundwater directly beneath the proposed route of the S2S will be located within the fill material overlying the bedrock, due to the proximity of the sea, the permeability of the overlying deposits and the significant depth to bedrock along most of the route. Also along most of the route, the groundwater will be hydraulically linked to the sea and affected by tidal movement.

Well card data from the GSI shows that there are only 9 no. wells in the vicinity of the proposed S2S route, but only a few show yield information (Table 5.12). The depth to bedrock is 10 m below ground level in the vicinity of Balgriffin and ranges from 6 – 40m below ground level along the southern section of the route. The majority of the wells in the area extend into the bedrock and therefore most groundwater abstracted in the area is from the bedrock.

Well Reference GSI Name Grid Reference Townland Yield Yield Class Easting Northing m3/d W1 3223SWW001 32173 24123 BALGRIFFIN 196 Good W2 3221NWW001 32120 22690 FOXROCK 54.5 Moderate W3 3221NWW002 32080 22120 BALLYBETAGH 5.4 Poor W4 3221NWW003 32340 22320 LOUGHLINSTOWN 220 Good W5 3221NWW004 32430 22030 SHANKILL 10.5 Poor

Table 5.12 GSI Well Card Data - Yields in the Dublin Bay Area

From the GSI well card data presented in Table 5.12, it can be seen that abstractions of up to 196 m3/day are obtained from the bedrock aquifer. Yield class ranges from poor to good.

The GSI, EPA and the Department of Environment and Local Government (DoELG) have developed a programme of Groundwater Protection Schemes, with the aim of maintaining the quantity and quality of groundwater in Ireland, and in some cases improving groundwater quality, by applying a risk assessment approach to groundwater protection and sustainable development.

The Groundwater Protection Scheme divides a chosen area into a number of Groundwater Protection Zones, according to the degree of protection required for the aquifer. These zones are based on both aquifer vulnerability and the degree of importance the aquifer holds; regional, local or not important.

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The Groundwater Protection Scheme for Dublin is currently being completed. This protection scheme will outline the degree of vulnerability of the aquifers in the county, and guidelines as to how to protect these aquifers.

The section of the route from Sutton to Blackrock is located on an aquifer that is generally moderately productive in local zones and from Blackrock to Sandycove the route overlies a bedrock aquifer, which is generally unproductive except in local zones 6. However, water supplies would not be abstracted from the aquifers along the coast, due to high saline content.

As the proposed S2S route is so close to Dublin Bay, the groundwater underlying the route is affected directly by the coastal water, in terms of water levels (tidal effects) and water quality (high salinity). The difference in the groundwater level between low tide and high tide in Dublin Bay can be as much as 0.4m in some areas.

There is a significant portion of the proposed route through Clontarf, Irishtown and Sandymount that will cross land that has been reclaimed from the Bay over the last two centuries. Traditionally the material used for reclamation in Dublin included construction and demolition waste, waste topsoil and municipal and industrial wastes. There were also a number of landfill sites in these areas. There are no records available as to the exact types and qualities of materials that were landfilled. It is unlikely that significant quantities of industrial wastes could have been dumped in these, as during much of the operating lifetime of the landfills, the Irish economy was not industrialised to any great degree. However, the groundwater in these areas may be contaminated and landfill materials may impede the ingress of water in that area.

In Dublin Bay, the groundwater gradient is generally towards the sea. Any leachate from the landfill areas above the high tide level would flow into the sea where dilution with the sea water may decrease the leachate concentrations to acceptable limits. Groundwater resources and watercourses should not be significantly affected by the leachate 9.

5.3.4 Sea Level Rise The Intergovernmental Panel on Climate Change (IPCC) indicates that the temperature of the Earth could be up to 5.8oC warmer by the year 2100 if no preventative measures are taken 5. The resulting thermal expansion of the oceans supplemented by more rapid melting of glaciers and ice caps is expected to increase average sea level. In Ireland, the sea level is expected to rise by 17-31cm in relative sea level around the coast by 2030 5. The impact of sea-level change will be seen in a number of ways. Firstly, low- lying lands will be subject to gradual inundation of estuaries, bays or behind natural coastal barriers. Secondly, the frequency of major storms, and storm surges arising from climate change, which combined with high tides and wind direction can cause considerable damage will increase. Even with a slight rise in sea level, flooding and storms that currently occur every 100 years might by the year 2030, be expected to occur every 5 years, apart from the increased storminess, and severity of storms, expected due to climate change 5. The east coast of Ireland experiences lower wave energy levels than the west coast but has more potential for shoreline erosion due to the “softer” nature of

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the coast 5. Coastal groundwater tables will rise as sea level rises, making drainage more inefficient. Low-lying areas around the coastline of Dublin Bay could be endangered by increased erosion or flooding.

5.3.5 Coastal Erosion There is firm evidence that rising sea-levels and increasing storm frequency and wave energy can increase the rate of erosion and the incidence of storm and flood-related events such as land-ward incursion, wave damage and flooding.

5.3.6 Wave Direction Dublin Bay is a horseshoe bay and so accommodates all wind directions; however the prevailing wind is from the south and west. At Sutton, the north end of the S2S route, the tide can be strong when it is going out and at high tide the sand spit can create hollow waves at the north end of Dollymount beach on an ebbing tide. The waves along Dollymount beach, west of the route, are not powerful but can reach several metres in height on certain days. The prevailing wind direction on the north side of Dublin Bay is southwesterly. Along the coastline at Salthill (behind Dun Laoghaire Harbour), wave action tends to be slight, however significant wave action has been noted further to the north of Salthill, towards Maretimo. Wave overtopping of the sea wall has also been noted at Blackrock Station during easterly gales. Waves are also known to propagate along the sea wall at Sandymount and in a south easterly storm event can run parallel to the coast and overtop the sea wall along Beach Road.

It is likely that the S2S route would have to be closed during periods of significant wave action which could lead to overtopping. These conditions, which would typically be during an easterly or south easterly gale, tend to occur a number of times each year. The Hydrological Model prepared as part of the Dublin Bay Flood Study by Dublin City Council can be used to predict wave height, using such input parameters as wind speed, direction, atmospheric pressure, rainfall and position within the tidal cycle, and it is envisaged that this model could be used to provide an "early warning system” for Dublin, in terms of flood risk, and also a warning of times when the S2S should be closed to the public, if a significant risk of wave overtopping occurs.

5.4 Constraints

This section outlines any possible constraints the proposed route may have during the construction and operational phase as a result of the hydrology of the areas along the proposed route.

5.4.1 Construction

The proposed S2S development will primarily consist of the extension of the sea wall, construction of a cantilever or pier structure along sections of the route and expansion of existing cycle/pedestrian tracks.

The extension of the sea wall and construction of a cantilever or pier structure will necessitate crossing a number of streams and rivers along the coastline many of which are considered significant in terms of amenity and fish life.

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Most of the streams along the route convey significant volumes of urban drainage to the Bay and are running near to capacity in many cases during heavy rainfall events. Any bridge structures used to cross these channels will be required to be designed such that the channel dimensions are in no way altered and this may be an opportunity to provide a wider mouth to each channel, to enable channel widening works at a later date, if the Local Authority intends to widen any channel as part of flood relief measures.

The close proximity of the sea, and the rivers and streams which S2S will cross means that the minimization of the risk of water pollution during construction will be a central theme of the construction methodology for the route. An Environmental Management Plan (See Appendix B) will be prepared for the construction and operational phases of the development to ensure all construction related impacts are controlled and mitigated. A detailed discussion of mitigation measures is provided in the following section. As discussed in the Soils and Geology section (Section 4), there is a significant portion of the proposed route that will cross land that has been reclaimed from the Bay over the last two centuries. The material used for reclamation in Dublin included construction and demolition waste, waste topsoil and municipal and industrial wastes. Any material excavated from this area may be contaminated and will need to be stored in suitable metal storage containers, pending suitable disposal.

There are a number of surface water drain outfalls that discharge to Dublin Bay,whichwillhavetobecrossedbytheroute.Restrictionoftheflowof these outfalls could lead to drainage problems in the area. Care will have to be taken during the construction phase so as not to restrict the outfalls. Foul and surface water drainage pipes will be crossed along sections to route and this may act as a constraint, in that access may be required along certain sections of the pipes, for maintenance purposes and therefore the design of the S2S will have to ensure that this access is maintained. The location of the drainage assets should be noted if excavation work is to take place along this section to ensure that pipes are not restricted or damaged. The Local Authority should be consulted as to what access the Local Authority will require for ongoing maintenance or emergency works. There are 2 no. sewage pumping stations, one located adjacent to the junction of the Dublin Road and Baldoyle Road and the second one at the Kilbarrack Road junction. The pumping stations will need to be incorporated into the design of the route. There is also a wastewater services hut located on the promenade on the Clontarf Road, which will also have to be incorporated into the route. From Sandycove, a Foul Sewer runs east along Sandycove Avenue, close to the sea wall just beside the start of the park. This sewer runs behind the old clubhouse (landward side) before running along the coast. There is a concrete ledge along the front of the sea wall at the park, which is the culverted sewer, which has been damaged over the years by the sea. The Local Authority has advised that this culverted drain would not support a pathway and they should be consulted before any construction of the route is carried along this section of the route.

Water supply pipes will be crossed along various sections of the S2S route. The location of the water supply pipes should be noted if excavation work is to

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take place along these sections to ensure that pipes are not restricted or damaged.

Anglers collect bait from the strand along the proposed route between Sutton and Clontarf and Sandymount and Sandycove. It will be necessary to ensure that there are sufficient access points to the strand during the construction phase of the route.

Sea Level Rise Sea level rise should be taken into account when designing the height of the route above sea level. As discussed in section 5.3, the predicted rise in Ireland is in the range 17-31cm by the year 2030 5. The Dublin Flood Study, which is currently being completed by Dublin City Council, reviews the impacts of sea level rise on Dublin Bay. In particular the design of the stretches of route between Wooden Bridge and Alfie Byrne Road and at Sandymount have been developed in anticipation of the recommendations of the Flood Study Report. The study should be consulted with regard to sea level rise data for the bay when further developing the design of the route.

5.4.2 Operation

The proposed S2S route will involve the construction of an additional impermeable area, over and above the existing impermeable area over which the proposed route will be constructed (a significant area on which the proposed route will be situated is covered by existing hard standing surfaces in the form of promenades, roads and parks). There will be an increase in the surface water run off from the additional hard standing area constructed.

Access to the drainage assets along the proposed route will be necessary during the operation of the route for maintenance of the foul, surface water and mains drainage system by the local authority. The Council will have to be consulted regarding the access required to drainage underlying the route.

Anglers collect bait from the strand along the proposed route between Sutton and Clontarf and between Sandymount and Sandycove. It will be necessary to ensure that there are sufficient access points to the strands during the operational phase of the route.

5.5 Mitigation Measures  In order to minimise the potential impacts from the development, the following mitigation measures will be implemented. These measures will ensure that contamination of groundwater and surface water does not occur during construction and operation of the S2S cycle/pedestrian track.

The Department of the Marine and Natural Resources published guidelines in 1997 designed to ensure the impact of construction work on the water environment is minimised10. The UK Department of the Environment has also published guidance as to the approach to minimize impacts of construction and operation of developments on the water environment11. These guidelines have informed and aided the selection of the mitigation measures outlined in the following paragraphs.

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An Environmental Management Plan (EMP) will be implemented as part of the design, planning, construction and operational stages of S2S. In terms of water quality, the EMP will ensure that any water quality issues are dealt with at an early stage of the development, and the avoidance or mitigation of any water quality impacts and can be integrated into the overall design of S2S (See Appendix B of this report).

5.5.1 Construction To minimize any impact on the sea and freshwater from material spillages, all oils, solvents and paints used during construction will be stored within temporary bunded areas. Oil and fuel storage tanks will be stored in designated areas, and these areas will be bunded to a volume of 110% of the capacity of the largest tank/container within the bunded area(s) (plus an allowance of 30 mm for rainwater ingress). Filling and draw off points will be located entirely within the bunded area(s). Drainage from the bunded area(s) will be diverted for collection and safe disposal.

Where possible refuelling of construction vehicles and the addition of hydraulic oils or lubricants to vehicles, will take place in a designated areas, away from the sea or freshwater. In the event of a machine requiring refuelling outside of this area, fuel will be transported in a mobile double skinned tank. An adequate supply of spill kits and hydrocarbon adsorbent packs will be stored in this area. All relevant personnel will be fully trained in the use of this equipment. These measures will ensure that accidental inputs to and subsequent contamination of ground water and surface water do no occur during normal and or emergency conditions.

Any potentially hazardous waste will be stored within suitable metal storage containers, away from watercourses and surface water drains prior to removal by an approved waste management contractor for off-site treatment/recycling/disposal. Any other building waste will be disposed of to on-site skips for removal by a duly approved waste management contractor.

The location of the surface water, foul water and mains water drainage assets will be noted if excavations are to take place to ensure that drains are not damaged or blocked and to ensure that there is access to the drainage assets for maintenance works.

The predicted sea level rise will be taken into account when designing the height of the route above sea level.

Access points to the strand during the construction phase of the S2S route will be provided to allow anglers to collect bait from the strand.

5.5.2 Operation

Access to the drainage assets along the proposed route will be provided for maintenance of the foul, surface water and mains drainage system by the council. The local authority will be consulted to determine the access requirements in each section.

Access points to the strand from the operational S2S route will be provided to allow anglers to collect bait from the strand.

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5.6 Possible Impacts

5.6.1 Construction

The impacts associated with the construction phase of the proposed S2S cycle/pedestrian route are predicted to be short term and of a neutral nature.

The close proximity of the S2S route to the sea, and the rivers and streams means that there is a risk of water pollution during the construction phase of the development. The minimization of the risk should be incorporated in the construction methodology for the route. As discussed in the previous section, an Environmental Management Plan (See Appendix B of this Report) will be prepared for the construction and operational phases of the development to ensure all construction related impacts are controlled and mitigated. A detailed discussion of mitigation measures is provided in the previous section.

As the majority of the proposed route is situated where a hard standing surface exists, sections of this impermeable surface may need to removed during the construction phase. Some subsoil will also be removed during the construction works but these works will not involve excavation of bedrock. These areas will be resurfaced with impermeable surfaces. There will be a net increase in impermeable surface area due to the extension of the sea wall and the expansion of existing cycle/pedestrian tracks and thus a marginal although not significant increase in surface water runoff from these areas.

There are a number of watercourses, which enter Dublin Bay along the proposed route. The proposed route will cross these; however, there will be no uncontrolled discharge to any watercourse during construction. The potential impact of water emissions from the construction phase of the S2S route on Dublin Bay will therefore be imperceptible.

Any potentially contaminated materials excavated during the construction may cause pollution watercourses and surface water if mitigation measures are not implemented.

Fuels, oils and lubricants will have to be stored on site, as the machinery will be in place for relatively long periods of time during the construction phase of the project. There is a possible negative impact on the water environment if mitigation measures are not properly implemented during construction on the foreshore.

With the correct storage and refuelling practices employed on site, the risk of pollution to the ground is removed. The presence of spill kits on the site will ensure that in the unlikely event that any accidental leaks or spillages of fuels or oils are not retained in bunded areas these spills or leaks will be cleaned up immediately. The impact of the construction works on the groundwater environment is therefore predicted to be neutral and short term.

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5.6.2 Operation

The impacts associated with the operational phase of the proposed S2S route development can be characterised as neutral.

There will be no significant increase in the surface water runoff as a result of the proposed S2S cycle/pedestrian route development. The overall impact on the surface water environment of surface water discharges from the cycle/pedestrian track can therefore be classed as neutral.

5.7 Recommendations and Further Studies

It is recommended that an Environmental Management Plan (EMP) be developed for the construction and operational phases of the development. The construction methodology for the S2S route must be developed with the protection of water quality as a guiding principle. A suitably qualified water quality consultant should form part of the team, which develops the construction methodology for the project.

It is also recommended that signage that will be provided along the route to display information on the water amenity of Dublin Bay.

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