10 Hydrology & Drainage

Transcription

1 10 Hydrology & Drainage Executive Summary 10.1 This chapter reports on an assessment of the project (see Chapter 4) at George Best Belfast City Airport (GB BCA), which includes additional car parking and aircraft parking; on the receiving water environment, including surface water quality, site runoff characteristics and potential flood risk. It summarises the relevant legislation and guidance and provides appropriate baseline information, enabling the potential effects to be identified Aspects of the design, construction and operation of the site that may potentially impact on the receiving water environment have been identified and the pathways for adverse effects assessed. It has been determined that without mitigation the potential development has the potential to cause adverse changes of major significance Mitigation proposed includes (but is not limited to): Optimisation of design of site elements to minimise impact on the water environment; Implementation of a surface water management plan comprising the use of SuDS (drainage) and silt management; Construction phase pollution prevention procedures; and Recommendation for the implementation of an emergency response / evacuation plan in the event of a coastal flood event Monitoring and validation of the mitigation methods would be provided through physicochemical water quality monitoring, which would validate the performance of the pollution prevention measures Implementation of the mitigation proposed would result in no significant residual effects to the receiving hydrological environment as a result of the project development, therefore the modification is considered acceptable in terms of its impact on the receiving hydrological environment. Introduction 10.6 This assessment determines the potential effects of the project (see chapter 4) at GB BCA, Sydenham Bypass, Belfast, upon the receiving hydrological environment, and related impacts upon the development caused by the site hydrology and receiving water environment. Consideration has also been given as to how the site drainage may be affected The changes proposed are broadly classified into two main categories, namely, change in use of the existing site and physical changes to the existing site. 136

2 10.8 The assessment techniques used are aimed at identifying hydrological constraints on the layout of the potential physical changes, including areas which should be avoided and areas in which mitigation measures would be required Chapter 4 (Project Description) provides a full description of the project. Scope of Assessment This chapter reports on an assessment of the effects of the project on hydrology and surface water quality. The assessment covers the construction, operation and maintenance of the physical changes. The chapter identifies and assess the potential effects on the following: Existing hydrological conditions, including: o Flooding and impediments to flows o Runoff rates and volumes Terrestrial and aquatic surface water dependant areas of environmental / scientific interest Water quality of surface waters including abstractions Water quality of surface water discharges from the site In order to quantifiably assess the preceding, this chapter: Outlines relevant policy relating to the water environment Summarises consultation responses in relation to this assessment Provides baseline information and identifies sensitive receptors Identifies potential effects, including potential cumulative effects Assesses the significance of any adverse impacts and resulting effects based on the magnitude of the impact and the sensitivity of the receptors Discusses management of design evolution, and detailed mitigation measures Provides a residual impact assessment Discusses cumulative impacts of the project in conjunction with proposed and existing developments in the vicinity Study Area The hydrological and water quality study area includes the airport and the wider area of associated surface water catchments The study area is as shown on Figure Potential effects were considered: Within the site Within the context of any potential downstream of wider catchment effects Legislation and Policy Framework Environmental planning policy and industry best-practice guidance relevant to an assessment of site hydrology and the water environment are summarised in the following sections. 137

3 Legislative Policy Key legislative drivers relating to the water environment which have been considered within this assessment are listed below: EU Legislation Water Framework Directive (2000/60/EC) Freshwater Fish Directive (2006/44/EC, replacing 78/659/EEC) Groundwater Daughter Directive (2006/118/EC) Environmental Liability Directive (2004/35/EC) NI Legislation Water Framework Directive (Priority Substances and Classification) Regulations (NI) 2011 Control of Pollution (Oil Storage) (Northern Ireland) Regulations 2010 The Environmental Liability (Prevention & Remediation) Regulations (Northern Ireland) 2009 Groundwater Regulations (Northern Ireland) 2009 The Private Water Supplies Regulations (Northern Ireland) 2009 Water Supply (Water Quality) Regulations (Northern Ireland) 2007 Water Environment (Water Framework Directive) Regulations (Northern Ireland) 2003 Drainage (Environmental Impact Assessment) Regulations (Northern Ireland) 2006 The Drainage (Amendment) (Northern Ireland) Order 2005 The Water Environment (Water Framework Directive) Regulations (Northern Ireland) 2003 The Environment (Northern Ireland) Order 2002 Water (Northern Ireland) Order 1999 Groundwater Regulations (Northern Ireland) 1998 The Surface Waters (Dangerous Substances) (Classifications) Regulations (Northern Ireland) 1998 The Nature Conservation and Amenity Lands (Northern Ireland) Order 1985 Drainage (Northern Ireland) Order 1973 Water Act (Northern Ireland) 1972 Fisheries (Northern Ireland) Act UK Legislation UK TAG on the WFD (UK Environmental Standards & Conditions) 2008 Planning Policy Although the potential physical aspects of the project are permitted development Planning Policy Statement 15: Flood Risk (June 2006) provides the context for the undertaking of this assessment and therefore is relevant The objectives of PPS15 are addressed through four policies, namely: 138

4 FLD1: Development will not be permitted within flood plains unless it is of overriding regional importance or falls within a set criteria to be considered exceptional to the Policy; FLD2: Development will not be permitted that would impede the operational effectiveness of flood defences or impede access for maintenance; FLD3: Development will not be permitted where it is known to be at risk of flooding from sources other than river / coastal floodplains, or where the development will cause increased flood risk elsewhere; FLD4: Development including requiring extensive culverting or canalisation of a watercourse will only be permitted in exceptional circumstances Consideration has been given to the Revised Planning Policy Statement 15 (dpps15) Planning and Flood Risk (issued as draft for consultation October 2013). Whilst the draft policy is not current at the time of writing, it has been established that there are no fundamental changes which would affect the outcome of this assessment Revised Draft Planning Policy Statement 15 in addition to the above stated FLDs 1-4; FLD5: New development will only be permitted within the potential flood inundation area of a controlled reservoir as shown on the Strategic Flood Map unless the stated exceptions are adhered to There are no reservoirs known to be located in the hydrologic catchments upstream of the project. Industry Guidelines The following guidelines have been used in the preparation of this assessment and associated assessments: CIRIA Research Project 624 Development and Flood Risk: Guidance for the Construction Industry CIRIA Research Project 635 Designing for exceedance in Urban Drainage good practice Other relevant guidance includes: Culvert design and operation guide (C689) (CIRIA, 2010) DEFRA Good Practice Guide for Handling Soils (MAFF 2000) Control of water pollution from construction sites. Guidance for consultants and contractors (C532) (CIRIA, 2001) Environmental good practice onsite (C650) (CIRIA, 2005) Environment Agency Policy Regarding Culverts: Technical Guidance on Culverting Proposals (EA, 1999) The Pollution Prevention Guidelines (PPGs), published by the Northern Ireland Environment Agency (in conjunction with the Environment Agency for England and Wales, and the Scottish Environment Protection Agency) include the documents referred to below, which are the principal documents used for guidance on preventing contamination of surface and ground water from construction activities. Those relevant to this assessment include: 139

5 PPG1: General guide to the prevention of pollution PPG2: Above ground oil storage tanks PPG3: Use and design of oil separators in surface water drainage systems PPG4: Treatment and disposal of sewage where no foul sewer is available PPG5: Works and maintenance in or near water PPG6: Working at construction and demolition sites PPG8: Safe storage and disposal of used oils PPG21: Pollution incident response planning PPG26: Storage and handling of drums & intermediate bulk containers Consultation Consultation to form opinion and requirements with regards to surface water and water quality was sought from the organisations listed in Table Consultation responses are included in Appendix A summary of the specific requests made by the various consultees is included in the following table. Site specific input provided is included in the following baseline site assessment. Consultees Comments DARD Rivers Agency Rivers Agency have indicated through correspondence that; The Q200 coastal flood level for the site is 3.17mAOD. This figure does not take account of climate change or wave action. NIEA Water Management Unit Provided information on; WFD & FFD classifications of nearby water quality monitoring stations and watercourses. WFD monitored water bodies and their 2012 classifications within 10 km of the site. Chemical sample results for nearby groundwater monitoring stations for sampling between December 2001 November Historical abstractions within 10 km of the site. 48 Current abstractions within 10 km of the site. Industrial Consents to Discharge within 10 km NIW Operational Assets within 10 km 140

6 Consultees Comments NIEA Drinking Water Inspectorate DWI only holds information on private water supplies (PWS) registered with the Inspectorate under The Private Water Supplies Regulations (Northern Ireland) 2009 and do not hold information on private water supplies which supply single dwellings. DWI provided details of; 14 PWS; all within 10 km of the site. 12 Dairy Farms using a PWS; all within 10 km of the site. Table Effect Magnitude Criteria: Summary of Consultation Assessment Methodology This hydrology assessment has been undertaken using a qualitative assessment based on experienced professional judgement and assessment of compliance with statutory and industry guidance, including site visits for verification The desktop study involved collation and assessment of the relevant information from the following sources: Ordnance Survey raster and vector mapping in addition to aerial photography to assess land usage on the site and its environs and to identify water features and watercourse catchments Review of the NIEA river quality data and natural heritage data Review of Northern Ireland Strategic Flood Map - Rivers & Sea Review of NIEA DWI data Review of NIEA Water Management Unit Data Review of CEH Flood Estimation Handbook (Version 3) for details of river catchment data Review of available site topographic survey and LiDAR information. Site walkover observations Assessment of Effects Determination of Magnitude and Significance Criteria This assessment determines impact of the project on the baseline (current) scenario. The significance of identified potential impacts is defined by the combination of the magnitude of potential impact (Table 10.2) and the sensitivity of the receptor (Table 10.3). Magnitude of Effect The magnitude is influenced by the timing, scale, size and duration of the potential hazardous effect, as defined in the following table. 141

7 Magnitude of Potential Impacts Definition Major Adverse Fundamental adverse change to hydrological conditions (including deterioration in water quality) or flood characteristics resulting in temporary or permanent consequential changes. Intermediate Adverse Detectable adverse change to hydrological conditions or flood characteristics resulting in non-fundamental temporary or permanent consequential changes. Some deterioration in water quality likely to temporarily affect most sensitive receptor. Minor Adverse Detectable but minor adverse change to hydrological conditions or flood characteristics. Drinking water or environmental water quality standards are not exceeded and level of change is unlikely to affect the most sensitive receptor. Negligible Unquantifiable or unqualifiable change in hydrological conditions, floodplains, or water quality. Temporary insignificant change in hydrological and water quality conditions not exceeding those expected due to naturally occurring fluctuations. Beneficial Beneficial change in hydrological, water quality, or flood characteristics. Table Effect Magnitude Criteria Sensitivity/Importance The sensitivity of the receiving environment has been categorised on a scale of Low to High in accordance with the criteria provided in the following table. Sensitivity criteria are based on: the vulnerability of a receptor to a particular pressure (degree of environmental response to any particular impact); and the value of the receptor (e.g. an area of international importance should be considered more sensitive to impact than an area of little or no conservation value) The sensitivity criteria used for this site are presented in Table

8 Sensitivity of Environment Definition High Watercourse with pristine or near pristine water quality. Environmental equilibrium highly prone to natural fluctuations and cannot absorb further change without fundamentally altering its present character. Receptor is of high environmental importance, i.e. nationally designated sites such as Areas of Special Scientific Interest (ASSIs), or non-designated sites meeting ASSI selection criteria, National Nature Reserves (NNRs), Marine Nature Reserves, Nature Conservation Review Grade 1 sites (Ratcliffe 1977); internationally designated or proposed sites, such as RAMSAR Sites, Special Protection Areas, Biosphere Reserves, Special Areas of Conservation, or otherwise meeting criteria for international designation. NIEA General Quality Assessment rating A (Very Good). Designated for freshwater ecological interest e.g. salmonid fishery and/or salmonid spawning grounds present or freshwater pearl mussel. Hydrologically highly-sensitive feature (other than watercourse) that currently supports particular species protected by national / international designation or legislation. Surface water subject to abstraction for public drinking water supply, private water abstractions for populations exceeding 25 people, or large scale industrial/agricultural abstractions. Watercourse with significant active floodplain area. Water widely used for recreational activities directly related to water quality i.e. swimming, salmon fishery etc. Medium Watercourse whose environmental equilibrium copes well with all natural fluctuations but cannot absorb some changes greater than this without alteration of its present character. Receptor is of medium environmental importance or of regional value. NIEA General Quality Assessment (GQA) rating B (Good) or C (Fair). May be subject to improvement plans by NIEA as part of Water Framework Directive requirements. Designated cyprinid fishery, possible salmonid species present and catchment locally important for fisheries. Hydrologically highly-sensitive feature (other than watercourse) that has the potential to support particular species protected by national / international designation or legislation. Surface water subject to abstractions for private water supplies for 143

9 Sensitivity of Environment Definition populations less than 25 people. Some active floodplain area. Non-statutory designated areas, such as Sites of Local Nature Conservation Importance (SLNCIs). Low Watercourse whose environment equilibrium is stable and is considered resilient to changes greater than natural fluctuations without detriment to its natural hydrological morphology and water quality characteristics. Receptor is of low environmental importance, i.e. NIEA GQA Grade D or below and fish sporadically present or restricted. Not subject to improvement plans by NIEA as part of Water Framework Directive requirements. Heavily engineered or artificially modified; may dry up during dry spells (no base flow). No drinking water supplies or small scale industrial/agricultural abstractions. Not used for recreation or used as flood storage area. Table Sensitivity Criteria Significance of Effect The combination of magnitude and sensitivity are combined to produce a significance matrix as per Table

10 Magnitude Potential Impact of Sensitivity Low Medium High Major Moderate Major Major Intermediate Slight Moderate Moderate Minor Slight Slight Slight/Moderate Negligible Neutral Neutral Neutral Beneficial Neutral Neutral Neutral Table Significance Matrix The assessment of effects considered likely to arise due to the project is based on significance prior to mitigation All levels of significance in excess of neutral require further consideration and may require proposals for mitigation or management to reduce the level of significance of effect. Limitations of the assessment The following are identified as limitations of the assessment Digital terrain model data (LiDAR) indicates that site levels vary between 2.8mAOD and 4mAOD (approximately). LiDAR information does not have the same level of accuracy as a site specific survey. The level of accuracy of the LiDAR data has been assessed through comparison with site specific topographical survey. The extents of the survey information provided is restricted to manhole cover levels located in the old terminal and surrounds, the main terminal building and surrounds and the short stay car park This assessment relies in part on information gathered as part of previous studies. Where information has not been sourced directly this will be cleared stated within this assessment. Baseline Conditions The following information has been gathered through desk study and field analysis. 145

11 Surface Water Abstractions A review of NIEA DWI data indicates that all private water abstractions and dairy farms using private water supplies are located greater than one kilometre away from GB BCA and are therefore not hydrologically linked to the site A review of NIEA Water Management Unit (NIEA WMU) data indicates that there are no current/ historic abstractions likely to be impacted. Groundwater Two groundwater bodies have the potential to be impacted; Ards Peninsula and Belfast groundwater bodies are located east and southeast of GB BCA respectively. Groundwater within these bodies is located within a sandstone aquifer overlain with low permeability soils. Desk and Field Study Topography GB BCA is located on the A2 Sydenham Bypass, Belfast, Co. Antrim. The site is reasonably flat with localised falls towards the drainage inlets and collection points serving the site The site is bounded by the Sydenham By-pass along the south eastern boundary and Airport Road West / Heron Industrial Estate along north western boundary. The Conns Water forms a channel to the immediate southwest of the site and the Tillysburn Stream flows into the Kinnegar Water to the east and to the northeast. Land Cover and Existing Drainage Characteristics A site walkover survey was completed on 25 th July The site survey incorporated the majority of the site, including airside which was restricted in places (due to airside control restrictions) Landside, the site is predominately hardsurfaced; comprising terminal building, offices, car park areas, access roads and storage areas. There are a few small areas within the site which are landscaped or grassed and for the purposes of this assessment are considered as permeable surfacing. Airside, the site is significantly permeable surfacing (grassed areas) predominately located around the runway, with hardsurfaced areas comprising runways, taxi strips, aprons, storage areas and buildings The site is currently served by a conventional drainage system, with surface runoff collected in gullies and channels. Flow is conveyed in pipes to arrangements of sampling chambers and oil interceptors prior to being conveyed to the respective final point of discharge. There are five points of discharge from the site for surface runoff to the receiving watercourses. 146

12 10.50 Surface runoff flows are generally conveyed to the Tillysburn Stream / Kinnegar Water or the Conns Water / Mallusk Channel. Where sampling indicates an exceedance in discharge consent (Water Order 1999), surface runoff flows are diverted to the foul system as discussed below Contingency is in place for the containment of pollutants within surface runoff as follows; Apron and runway. All surface runoff flows pass via an oil interceptor, to a chamber which contains automated sampling equipment. Where conductivity of flow exceeds threshold levels (indicating presence of pollutant or contamination within the flow), penstocks within the diversion chamber diverts all flow to a containment lagoon, which has a volume of approximately 1,250m 3. Flows from the lagoon are pumped to a secondary diversion chamber (MH12), which allows for diversion of flow to either the NI Water foul sewer (which conveys flow to Kinnegar WWTW) or the local storm drain (via the oil interceptor located in the car park). Car park, terminal building roof area and access roads. All surface runoff flows are collected in a separate storm systems and pass via oil interceptors to the respective point of outflow. Foul flows generated by the site discharge to a NI Water combined trunk sewer via gravity The extent of area which has the potential to be modified from permeable area to impermeable area has been measured as 0.52ha. Table 10.5 provides an indication of the increase of surface runoff rates from potential changes. Return Period Runoff from areas identified as permeable (lps) Runoff from redevelopment to impermeable (lps) Increase in runoff (lps) 1 in 2 year (1hr) in 30 year (1hr) in 100 year (1hr) Flooding Initial Assessment Table Comparison of Surface Water Runoff Rates Anecdotal evidence obtained does not suggest any history of flooding at the site. Fluvial Flooding The site was reviewed with reference to the Strategic Flood Map (NI), developed by Rivers Agency in co-operation with the Department of the Environment and published November The Strategic Flood Map (NI): Flood Map Historic Flood Extents 147

13 indicates that no areas in the vicinity of the site have been affected by historic flood events No significant natural fluvial floodplain or flood storage areas have been identified on the site. Coastal Flooding The Strategic Flood Map (NI): Flood Map Rivers (Predicted 2030) indicates that the site is situated adjacent to the coastal floodplain of Belfast Lough and that the site may be affected Rivers Agency predicted coastal flood data for Belfast Lough indicates a Q200 (0.5% Annual Equivalent Probability) flood level of 3.17m AOD. This flood level is in excess of the lowest site level of 2.8m AOD. The low lying areas within the GB BCA site boundary are not identified as being directly connected by surface flow routes to the coastal floodplain. The effect of wave action is considered unlikely to affect the site given the degree of shelter provided by the sites location in conjunction with the Belfast Lough coastline. Preliminary flood extents mapping produced in the course of this assessment is included in Figure Surface Water (Pluvial) Flooding The Strategic Flood Map (NI): Flood Surface Water indicates that the site is potentially at risk of surface water flooding. Surface water flood extents coincide with existing level hard standing areas where ponding is likely. Drainage design would be designed to cater for surface water flooding. Preliminary flood extents mapping produced in the course of this assessment is included in Figure Sewerage / Infrastructure Failure Flooding No indication of urban drainage / sewer incapacity at the site or surrounding area was found in an initial evidence search. However, significant storm and foul sewerage infrastructure serving a portion of East Belfast does exist in the vicinity of the site in the form of a rising main The site is served by a conventional drainage system which is maintained on a cyclic basis by the site owners Flooding of the site due to sewerage / infrastructure failure is considered unlikely. Flood Defences There are no Rivers Agency designated flood defences within the boundary of the site or adjacent to the site. Therefore, assessment of flood risk in this regard is not applicable. Meteorological Data Summary Rainfall data for the catchment extracted from Centre for Ecology and Hydrology (CEH) Flood Estimation Handbook at location centroid IJ for the site is as follows: Annual Average Rainfall ( ): 955 mm 148

14 Annual Average Rainfall ( ): 913 mm Based on the Meteorological Office banding of annual average rainfall amounts, the above statistics indicate that rainfall at the site is within the 6 th highest band of rainfall (of 9 bands) and that the climate in the vicinity of the site is close to the UK average. Surface Water Quality NIEA provides information on the quality of watercourses across Northern Ireland. Watercourse reaches are given an overall classification for both chemical and biological quality No specific water quality data is available for the Tillysburn Stream, Kinnegar Water, Conns Water or the Sydenham Stream, within the WFD classification system The site is located within a coastal inter basin (UKGBNI8NE023) and is therefore not monitored under the WFD directive. Nearby WFD monitored watercourses which can be impacted by the inter basin include the Conns Water River, Belfast Harbour and Belfast Lough. The Lagan Local Management Area Action Plan (2011) and Belfast Lough LMA Action Plan (2012) will apply to these downstream areas There are no WFD or FFD monitoring locations in the vicinity of the site. Independent Water Quality Monitoring In addition to a review of water quality data held by statutory agencies, independent water quality sampling is undertaken on an ongoing basis as part of compliance with the licence to discharge from various parts of the site The suite of parameters identified as required for analysis by the discharge licence is defined as Ammoniacal Nitrogen as N (mg/l), ph, Suspended Solids (mg/l) and visible signs of Oil or Grease. To supplement the regular discharge compliance monitoring and provide further data upon which to base this assessment a more extensive suite of physico-chemical monitoring was undertaken on 25 th July It is noted that sampling was undertaken after a prolonged dry period Water quality test results are measured for compliance against the key parameter limits outlined in: The Water Framework Directive (Priority Substance and Classification) Regulations (Northern Ireland 2011 [WFD] UK Technical Advisory Group on the Water Framework Directive (UK Environmental Standards & Conditions) 2008 {UK TAG} Independent sampling was undertaken at five locations shown on Figure Commentary on results obtained is as follows: All sample parameters were within legislative parameters, which the exception of turbidity which indicated slight exceedances. No traces of TPH or PAH were recorded and heavy metal were within guidance limits. 149

15 10.73 There were no other notable anomalies or indicators of pollution within the results obtained. Full results are included in Appendix Surface Water Abstractions and Discharges Abstractions Information has been received from (NIEA WMU) and the DWI regarding all known nonpotable abstractions and discharges within a 10 km radius of the site NIEA WMU i) NIEA WMU data indicated one current surface water abstraction point along the site boundary (Bombardier Aerospace) the company abstracts from a surface water source on the western site boundary; this point is upstream of the Belfast City Airport Watercourse. ii) Only one historical abstraction was noted within 2 km of the site; it is located upstream of the site and is therefore unlikely to be impacted by any potential works. WMU also stated that accuracy and currency of any historical information held within the dataset cannot be stated with any confidence as historical abstraction data was provided from a number of historical data sets. iii) All other WMU current and historical abstractions from surface water or groundwater are greater than 2 km away from the site and therefore unlikely to be impacted Drinking Water Inspectorate (DWI) i) DWI only holds information on private water supplies registered with DWI under The Private Water Supplies Regulations (Northern Ireland) 2009 and does not hold information on private water supplies which supply single dwellings. ii) A review of the DWI data provided has indicated that there are no Private Water Supplies (PWS) or Dairy Farms abstracting from a PWS registered with the DWI within 1 km of the site. Discharges Information has been received from the NIEA WMU regarding all known NIEA Operational Assets and Industrial Discharge Consents within a 10 km radius of the site Four Industrial Consents and two NIW Operational Assets are located within or adjacent to the site boundary: i) Armstrong Meats discharging unspecified private sewage to a waterway. ii) Northstone Quarry discharging site drainage to a waterway. iii) Coastal Clear Water Ltd discharging unspecified private sewage to a waterway. 150

16 iv) Morrow Group discharging site drainage to a waterway. v) (Holywood Road CSO and Inverary Road CSO operational assets are located along the western site boundary An industrial consent exists for discharge of stormwater drainage from the GB BCA site at several locations; this should be maintained in accordance with relevant guidance as required All abstractions and discharges are detailed in Appendix 10.2 and shown on Figure 10.4 Abstractions & Discharges. Designations GB BCA is not situated within a Natura 2000 site, however, it is situated adjacent to Belfast Lough Special Protection Area (SPA), Area of Special Scientific Interest (ASSI) & Ramsar Site (approximately 390m), and in proximity to Outer Belfast Lough SPA/ASSI (approximately 510m) Belfast Lough falls within the North Eastern River Basin Management Plan for WFD purposes, and a duty exists upon the Department of the Environment to restore the status of the Lough to good status and/or ecological potential Inner Belfast Lough ASSI encompasses the southern part of Belfast Lough and is classified as an ASSI primarily due to its fauna. It includes areas of intertidal foreshore which form important feeding / roosting sites for wildfowl. Outer Belfast Lough ASSI is primarily important for the geological features of the area. Wildfowl are also supported and Outer and Inner Belfast Lough ASSIs are closely linked Belfast Lough ASSIs are designated for their geological features and fauna, and as such are not receptors subject to the effect of freshwater quality or rates / volumes of runoff. As such, no further consideration is required at these sites in relation to surface water hydrology The Inner Lough has been declared as a Eutrophic Sensitive Area, and has been designated as a shellfish water for the purposes of the EC Shellfish Waters Directive Areas of the Outer Lough are designated under the Nitrates and Bathing Waters Directives The appraisal classifies any likely significant impacts upon Belfast Lough as significant due to the range of statutory protections and designations which apply to the Lough It is noted that a number of other water bodies (namely, Belfast Harbour, Connswater Estuary & Lagan Estuary) are hydrologically connected to Belfast Lough and have also been designated under WFD and associated Directives. 1 EC Shellfish Waters Directive (2006/113/EEC) and The Surface Waters (Shellfish) Directions

17 10.89 Flow is discharged from site (from the area of the staff car park) to the Conns Water at the point of discharge to Belfast Lough (Conns Water Channel). For the purposes of this assessment, the Conn Water Channel will be considered to be part of Belfast Lough The following Sites of Local Nature Conservation Importance (SLNCIs) are located within 2km of the proposal site. Tillysburn SLNCI Belfast Harbour Estate (North Down) SLNCI Belfast Harbour Estate SLNCI Full details of designated nature conservation sites are set out in the Chapter 9 of the ES. Baseline Summary and Sensitivities The previous baseline assessment indicates a number of receptors that have the potential to demonstrate sensitivity to the project at GB BCA. These are: Type Receptor Sensitivity Rationale Belfast Lough (including Inner and Outer Lough, Belfast Harbour and Lagan Estuary) High Presence of ASSI, SPA & Ramsar No significant fisheries, significant active floodplain area, or abstractions. Hydrological Tillysburn Stream, Kinnegar Water, Conns Water, Sydenham Stream Medium No significant fisheries, significant active floodplain area, or abstractions. No recreational use. Tillysburn Stream has hydrological connectivity with Tillysburn SLNCI. Tillysburn SLNCI Medium Site is a non-statutory designated area. Belfast Harbour Estate (North Down) SLNCI Medium Site is a non-statutory designated area. Belfast Harbour Estate SLNCI Medium Site is a non-statutory designated area. Groundwater abstractions No groundwater abstractions downstream of the proposed works. Site predominately hardsurfaced with bound material (tarmac and concrete), in all areas where polluted runoff or spillages are likely to occur. All runoff from these areas conveyed by a sealed conventional drainage system. 152

18 Type Receptor Sensitivity Rationale Proposed car park will have low sensitive to material damage due to flooding. The Project (Flood Risk) Additional car park areas, additional aircraft waiting area High Risk to life caused by flooding to car park. Fluvial floodplains have not been identified as encroaching the GB BCA site boundary. Areas have been identified within the GB BCA site boundary, which are lower than the estimated Q 200 coastal flood level identified for Belfast Lough. Table Receptor Sensitivity Potential Effects Preamble This section describes the potential effects of the project based upon assessment of the changes described in the parameters plans which may occur during any construction and use of the airport relative to the identified receptors During any construction phases a number of activities may be undertaken on site, some of which would have the potential to modify hydrological regimes and affect the water quality in the receiving environment. Should any of the hardstanding areas referred to be delivered at any point, the site would have potential to be affected by the amended hydrological regime, including flooding During the ongoing operation of the site and in the event that any of the hardstanding areas referred to be are delivered there is potential for contamination of receiving watercourses due to spillage occurring at the site (if no mitigation measures are put in place). Modifying Influences Proposals have been developed for the provision of additional parking spaces should it be required. The existing taxi waiting area adjacent to the new staff car park may also be reconfigured increasing existing capacity Extended and reconfigured aircraft parking areas may be required involving the part demolition of the old terminal building and the resurfacing of the existing aircraft parking area. Full details are set out in Chapter 4 of the environmental statement. Potential Effects The potential effects on the surface water environment are summarised as follows: Potential for contamination of receiving waterbodies from construction runoff (from silt and potential contaminates present with excavated arising). Potential for increased flood flows entering the Tillysburn Stream due to alteration of drainage characteristics on the site. 153

19 Potential for hazards to the built environment and inhabitants due to proximity to flooding. Potential for increase in hydrocarbons (all trafficked areas) to be entrained within runoff. Potential increase of risk to water environment due to impact of or use of the following; o Fuel spillages o De-Icing Chemicals (Aircraft) o De-icing Chemicals (Apron/Taxiway Areas) o Fire Fighting Chemicals Mitigation and Enhancement The following Table 10.7 summarises the potential effects along with the anticipated causes and potential consequence, prior to any mitigation. Effect Caused By Consequence Changes in runoff and flow patterns Silt / suspended solid pollution of surface waters Additional impermeable surfaces may cause increased rate and volume of surface water runoff. Temporary activities required to construct infrastructure would require excavations, ground disturbance, stripping of soil, and temporary spoil deposition. Exposed soils have potential to release fine sediments in surface water runoff or where excavations come in contact with surface watercourses. Temporary surface water or shallow groundwater gathering in significant excavations has potential to be significantly polluted due to contact with excavated surfaces and aggregates. Discharging of untreated water by pump or gravity would cause release of potentially heavily polluted effluent to watercourses. Cause temporary or permanent increases in surface water runoff rates and volumes, leading to increased flood risk and increased effects of erosion and scour in down gradient watercourses. Cause temporary or permanent restrictions in watercourse channels, affecting upstream water levels and increasing flood risk. Cause reduced potential for groundwater recharge through reduction of permeable areas on the site. Sediments and debris entering watercourses have the potential to adversely modify stream morphologies, smother habitats, harm aquatic flora and fauna; and increase risk of blockage to culverts and drainage channels. 154

20 Effect Caused By Consequence Chemical pollution of surface waters Temporary presence of chemicals, fuels, and oils associated with construction activities on the site have potential to enter the surface water environment through accidental spillages, improper transport and refuelling, or inappropriate storage and disposal procedures, by gradual leakage or single failure of storage tanks or refuelling mechanisms. Presence of contamination within the areas proposed for the car park may be exposed during the construction process. Temporary presence of raw cementitious materials associated with construction activities on the site have potential to enter the surface water environment, affecting alkalinity levels with associated effects on fish and aquatic ecology. Permanent presence of oils, fuels and hydrocarbon associated with presence of vehicles within the car park for the life of the development has potential to enter the surface water environment. Application of De-Icing Chemicals (used on Aircraft, Apron/Taxiway Areas) for the life of the development has potential to enter the surface water environment. Discharge of Fire Fighting Chemicals (Aircraft) used during fire fighting training exercises has potential to enter the surface water environment. Oils, fuels and chemicals entering watercourses have the potential to adversely affect water quality, with associated effects to fish and aquatic ecology. Table Potential effects Construction & Operation Magnitude and Significance of Potential Effects Magnitudes of identified effects, and associated unmitigated significance of those effects, are determined in accordance with the rationale previously described Potential effects and their significance (without mitigation) are presented in the following table. 155

21 Receptor Receptor Sensitivity Potential Effect Magnitude of Effect (without mitigation) Unmitigated Significance High Pollution due release of silt / suspended solids, oils, fuels and chemicals. Nature and extent of construction activities anticipated on the site, without mitigation, has potential to cause a detectable change to water quality causing a nonfundamental temporary or permanent consequential change in the waterbody. Nonprevention of spillages during the operation of the site has potential to cause a detectable change to water quality causing a non-fundamental temporary or permanent consequential change in the water body. Major Major Adverse Effect Belfast Lough (including Inner and Outer Lough, Belfast Harbour and Lagan Estuary) Potential for loss of floodplain storage volume Potential for restriction of flood flows Loss of coastal floodplain would not result in a permanent change in flood level characteristics at or in proximity of the site Negligible Adverse Effect A restriction to flows, due to widespread or localised infilling of the coastal floodplain, or construction of a new structure within the coastal floodplain, would lead to a permanent change in coastal floodplain characteristics. Coastal flood levels would not be affected. Neutral Neutral Negligible Adverse Effect Potential for increased flood flows Development of the site will lead to a minor increase in surface water runoff from the site, contributing Belfast Lough. Due to the size and nature of the receiving waterbody, the increase would not have the potential to cause a permanent change to flood level characteristics downstream of the site. Neutral Negligible Adverse Effect Kinnegar Water Tillysburn SLNCI Belfast Harbour Estate (North Down) SLNCI Medium Pollution due to release of silt / suspended solids, oils, fuels and chemicals. Nature and extent of construction activities anticipated on the site, without mitigation, has potential to cause a detectable change to water quality causing a nonfundamental temporary or permanent consequential Major 156

22 Receptor Receptor Sensitivity Potential Effect Magnitude of Effect (without mitigation) Unmitigated Significance Belfast Harbour Estate SLNCI change in the Tillysburn Stream, Kinnegar Water and the Conns Water. Non-prevention of spillages during the operation of the site has potential to cause a detectable change to water quality causing a nonfundamental temporary or permanent consequential change in the waterbodies. Major Adverse Effect Potential for loss of floodplain storage volume Loss of coastal floodplain would not in a permanent change in flood level characteristics at or in proximity of the site Neutral Negligible Adverse Effect Potential for restriction of flood flows A restriction to flows, due to widespread or localised infilling of the coastal floodplain, or construction of a new structure within the coastal floodplain, would lead to a permanent change in coastal floodplain characteristics. Coastal flood levels would not be affected. Neutral Negligible Adverse Effect Potential for increased flood flows Development of the site will lead to an increase in surface water runoff from the site, contributing to Tillysburn Stream / Kinnegar Water. Slight Any increase would may have the potential to cause a change to flood level characteristics at and downstream of the site. Intermediate Adverse Effect Proposed infrastructure incl. car parking and aircraft waiting areas High Flooding Potential for flooding of car park and access roads if sited within coastal flood plains which could cause damage to property and risk to life. Major Adverse Effect Major Table Magnitude and Significance of Effects to Receptors 157

23 Design Evolution and Mitigation Measures Mitigation Preamble The primary adverse effects to the water environment and the development arise from: Pollution of watercourses Increased flooding due to increased rates of runoff and; Flooding of the development Mitigation of flood risk-related aspects primarily consists of design measures, with effort made to avoid the flood hazard, and avoid causing increased flood risk Mitigation of water quality-related aspects primarily consists of measures to be taken during the construction of the project. Mitigation through Design & Design Evolution Flooding has been assessed at preliminary design stage Due to the nature of the flood hazard, the primary means of reducing significant impact has been the identification of design levels and a means of safe access / egress routes to and from the locations of the site where changes are proposed Recommendations have been made for flood related emergency response / evacuation plans to be incorporated into the Health and Safety Information File for the site and incorporated into site management procedures Design of mitigation has been developed in accordance with best practice, using legislation and guidance as outlined previously in this assessment. Of particular importance are the implications of the Water Framework Directive; i.e. mitigation for all watercourses aim to preserve / improve existing water quality ratings as a minimum. Land Use Development within any area of floodplain has the potential to occupy volume previously available to flooding. In addition, development within the floodplain has potential to cause re-routing of natural out of bank flood flows Built development is therefore to be restricted to those areas lying outside of the Q100 fluvial floodplain. No raising of ground levels (by infilling or otherwise) is to be permitted in the area denoted as the Q100 fluvial floodplain, however, infilling may be permitted within the Q200 coastal floodplain upon agreement of the findings of the site specific Flood Risk Assessment with DoE Planning / Rivers Agency. Mitigation during Construction During any phases the site manager would ensure that mitigation measures as identified within this assessment were fully implemented, and that activities were carried 158

24 out in such a manner as to prevent or reduce effects. The following construction phasespecific measures would be implemented. Pollution Prevention Guidance To ensure best practice on site and to help avoid pollution release to watercourses and groundwater, the following NIEA Pollution Prevention Guidance (PPGs) would be adhered to: PPG1: General guide to the prevention of water pollution; PPG2: Above ground storage tanks; PPG3: Use and design of oil separators in surface water drainage systems; PPG4: Treatment and disposal of sewage where no foul sewer is available; PPG5: Works in, near or liable to affect watercourses; PPG6: Working at construction and demolition sites; PPG7: Refuelling facilities; PPG8: Safe storage and disposal of used oils; PPG13: Vehicle washing and cleaning; PPG18: Managing fire water and major spillages; and PPG21: Pollution Incident Response Planning Key requirements for control of chemical pollution risk are identified in the above guidance, and would include: Storage all equipment, materials and chemicals would be stored away from any watercourse or area denoted as a floodplain. Chemical, fuel and oil stores would be sited on impervious bases in accordance with PPG2 and within a secured bund of 110% of the storage capacity, within the lay down area. Vehicles and refuelling standing machinery would have drip trays placed underneath to prevent oil and fuel leaks causing pollution. Where practicable, refuelling of vehicles and machinery would be carried out on an impermeable surface in designated areas, well away from any watercourse, or drainage ditches, and would adhere to best practice as detailed in PPG7. Maintenance maintenance to construction plant would not be permitted on site, unless vehicles have broken down necessitating maintenance at the point of breakdown. All necessary pollution prevention measures would be put in place prior to commencement of maintenance in this instance. Excavations and Spoil Management; Soil and subsoil excavation and movement would be undertaken in accordance with best practice guidelines such as Good Practice Guide for Handling Soils (MAFF, 2000). Where practicable the upper vegetated layer would be stored separately in order to maintain vitality and used to re-cover excavations on completion of the construction phase. 159

25 Areas of stockpiled spoil: would not be permitted within previously denoted watercourse buffer zones; would be remediated such that there would be no contaminated runoff generated; would not be stored in areas designated as floodplain. Maintenance of Pollution Prevention Measures Any pollution prevention measures installed would be subject to a regular maintenance regime for the life of the construction phase in order to maintain functionality of all features. This would include unblocking of drains, maintenance of hardstanding surfaces, replacement of silt settlement features and removal of silt build-up from settlement features. Mitigation during Operation Drainage design would ensure that any areas for development could be drained without increased risk to the receiving aquatic environment. This would include the following (to be confirmed as part of any detailed design); All surface runoff flows from proposed car parking areas to be passed through full retention oil separator(s). All surface runoff flows from proposed aircraft waiting areas to pass via an oil interceptor, to a chamber which contains automated sampling equipment. Where conductivity of flow exceeds threshold levels (indicating presence of pollutant or contamination within the flow), penstocks within the diversion chamber diverts all flow to a containment lagoon, (volume to be confirmed as part of detailed design). Flows from the lagoon would be discharged to either the NI Water foul sewer (which conveys flow to Kinnegar WWTW) or the local storm drain (via the oil interceptor located in the car park), depending upon the level of treatment received. Pollution containment measures to fully consider the potential impact of larger aircraft using the site as part of any detailed design, i.e. larger fuel requirements may require larger containment requirements. Surface water drainage design would be as per the requirements of Sewers for Adoption Northern Ireland (WRc, 2009). For the purposes of this assessment it is assumed that all site drainage will drain to the Tillysburn Stream / Conns Water, subject to consent. The increased runoff rate and volume from the site will, if un-attenuated, result in a negligible increase in the Q 100 flow of the respective watercourses at the site. Drainage would be designed to have a free discharge at min. Q30 flood level, or where a risk of surcharge from downstream sewerage is anticipated, site drainage outfalls would be fitted with a non-return valve upstream of connection to the main sewer network. Access for maintenance of drainage including discharge locations would be detailed in as-built / health and safety information provided to the relevant adopting authority. 160