S10 Hydrology & Drainage FINAL - Planning Service · • Water Supply (Water Quality) Regulations ... Assessment Methodology 10.29 This hydrology assessment has been undertaken using

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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.

10.2 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.

10.3 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.

10.4 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.

10.5 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.

10.7 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.

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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.

10.9 Chapter 4 (Project Description) provides a full description of the ‘project’.

Scope of Assessment

10.10 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

10.11 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

10.12 The hydrological and water quality study area includes the airport and the wider area of

associated surface water catchments.

10.13 The study area is as shown on Figure 10.1. Potential effects were considered:

• Within the site

• Within the context of any potential downstream of wider catchment effects

Legislation and Policy Framework

10.14 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.

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Legislative Policy

10.15 Key legislative drivers relating to the water environment which have been considered

within this assessment are listed below:

10.16 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)

10.17 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 1966

10.18 UK Legislation

• UK TAG on the WFD (UK Environmental Standards & Conditions) 2008

Planning Policy

10.19 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.

10.20 The objectives of PPS15 are addressed through four policies, namely:

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• 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.

10.21 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.

10.22 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.

10.23 There are no reservoirs known to be located in the hydrologic catchments upstream of

the ‘project’.

Industry Guidelines

10.24 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”

10.25 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)

10.26 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:

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• 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

10.27 Consultation to form opinion and requirements with regards to surface water and water

quality was sought from the organisations listed in Table 10.1. Consultation responses

are included in Appendix 10.1

10.28 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 2012.

• 33 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

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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 10.1 - Effect Magnitude Criteria: Summary of Consultation

Assessment Methodology

10.29 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.

10.30 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

10.31 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

10.32 The magnitude is influenced by the timing, scale, size and duration of the potential

hazardous effect, as defined in the following table.

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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 10.2 - Effect Magnitude Criteria

Sensitivity/Importance

10.33 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).

10.34 The sensitivity criteria used for this site are presented in Table 10.3.

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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

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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 10.3 - Sensitivity Criteria

Significance of Effect

10.35 The combination of magnitude and sensitivity are combined to produce a significance

matrix as per Table 110.4.

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Magnitude of

Potential Impact

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 110.4 - Significance Matrix

10.36 The assessment of effects considered likely to arise due to the ‘project’ is based on

significance prior to mitigation.

10.37 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

10.38 The following are identified as limitations of the assessment.

10.39 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.

10.40 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

10.41 The following information has been gathered through desk study and field analysis.

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Surface Water Abstractions

10.42 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.

10.43 A review of NIEA Water Management Unit (NIEA WMU) data indicates that there are no

current/ historic abstractions likely to be impacted.

Groundwater

10.44 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

10.45 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.

10.46 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

10.47 A site walkover survey was completed on 25th July 2013. The site survey incorporated the

majority of the site, including airside which was restricted in places (due to airside control

restrictions).

10.48 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.

10.49 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.

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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.

10.51 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 1,250m3. 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.

10.52 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) 1.3 16.0 14.7

1 in 30 year (1hr) 2.3 34.7 32.4

1 in 100 year (1hr) 2.7 47.4 44.7

Table 110.5 - Comparison of Surface Water Runoff Rates

Flooding

Initial Assessment

10.53 Anecdotal evidence obtained does not suggest any history of flooding at the site.

Fluvial Flooding

10.54 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 2008. The Strategic Flood Map (NI): Flood Map Historic Flood Extents

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indicates that no areas in the vicinity of the site have been affected by historic flood

events.

10.55 No significant natural fluvial floodplain or flood storage areas have been identified on the

site.

Coastal Flooding

10.56 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.

10.57 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 10.1.

Surface Water (Pluvial) Flooding

10.58 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 10.1.

Sewerage / Infrastructure Failure Flooding

10.59 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.

10.60 The site is served by a conventional drainage system which is maintained on a cyclic

basis by the site owners.

10.61 Flooding of the site due to sewerage / infrastructure failure is considered unlikely.

Flood Defences

10.62 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

10.63 Rainfall data for the catchment extracted from Centre for Ecology and Hydrology (CEH)

Flood Estimation Handbook at location centroid IJ 38250 77000 for the site is as follows:

• Annual Average Rainfall (1941 – 1970): 955 mm

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• Annual Average Rainfall (1961 – 1990): 913 mm

10.64 Based on the Meteorological Office banding of annual average rainfall amounts, the

above statistics indicate that rainfall at the site is within the 6th 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

10.65 NIEA provides information on the quality of watercourses across Northern Ireland.

Watercourse reaches are given an overall classification for both chemical and biological

quality.

10.66 No specific water quality data is available for the Tillysburn Stream, Kinnegar Water,

Conns Water or the Sydenham Stream, within the WFD classification system.

10.67 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.

10.68 There are no WFD or FFD monitoring locations in the vicinity of the site.

Independent Water Quality Monitoring

10.69 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.

10.70 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 25th July 2013. It is noted that sampling

was undertaken after a prolonged dry period.

10.71 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}

10.72 Independent sampling was undertaken at five locations shown on Figure 10.3.

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.

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10.73 There were no other notable anomalies or indicators of pollution within the results

obtained. Full results are included in Appendix 10.4.

Surface Water Abstractions and Discharges

Abstractions

10.74 Information has been received from (NIEA WMU) and the DWI regarding all known non-

potable abstractions and discharges within a 10 km radius of the site.

10.75 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.

10.76 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

10.77 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.

10.78 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.

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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.

10.79 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.

10.80 All abstractions and discharges are detailed in Appendix 10.2 and shown on Figure 10.4

– Abstractions & Discharges.

Designations

10.81 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).

10.82 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.

10.83 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.

10.84 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.

10.85 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 Directive1.

10.86 Areas of the Outer Lough are designated under the Nitrates and Bathing Waters

Directives.

10.87 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.

10.88 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 2010

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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.

10.90 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

10.91 Full details of designated nature conservation sites are set out in the Chapter 9 of the ES.

Baseline Summary and Sensitivities

10.92 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

Hydrological

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.

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


Belfast Harbour Estate SLNCI


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.

153

Type Receptor Sensitivity Rationale

The Project (Flood Risk)

Additional car park areas, additional aircraft waiting area

High

Proposed car park will have low sensitive to material damage due to flooding.

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 Q200 coastal flood level identified for Belfast Lough.

Table 110.6 - Receptor Sensitivity

Potential Effects – Preamble

10.93 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.

10.94 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.

10.95 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

10.96 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.

10.97 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

10.98 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.

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• 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

10.99 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

Additional impermeable surfaces may cause increased rate and volume of surface water runoff.

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.

Silt / suspended solid pollution of surface waters

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.

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.

155

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 110.7 - Potential effects – Construction & Operation

Magnitude and Significance of Potential Effects

10.100 Magnitudes of identified effects, and associated unmitigated significance of those

effects, are determined in accordance with the rationale previously described.

10.101 Potential effects and their significance (without mitigation) are presented in the following

table.

156

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 non-fundamental temporary or permanent consequential change in the waterbody. Non-prevention 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 Adverse Effect

Major

Potential for loss of floodplain storage volume

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

Neutral

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

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

Kinnegar Water

Tillysburn 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 non-fundamental temporary or permanent consequential

Major

157

Receptor Receptor

Sensitivity Potential Effect

Magnitude of Effect (without mitigation)

Unmitigated Significance


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 non-fundamental temporary or permanent consequential change in the waterbodies.



Loss of coastal floodplain would not in a permanent change in flood level characteristics at or in proximity of the site


Neutral


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


Development of the site will lead to an increase in surface water runoff from the site, contributing to Tillysburn Stream / Kinnegar Water.

Any increase would may have the potential to cause a change to flood level characteristics at and downstream of the site.

Intermediate Adverse Effect

Slight

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

Table 110.8 - Magnitude and Significance of Effects to Receptors

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Design Evolution and Mitigation Measures

Mitigation Preamble

10.102 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.

10.103 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.

10.104 Mitigation of water quality-related aspects primarily consists of measures to be taken

during the construction of the project.

Mitigation through Design & Design Evolution

10.105 Flooding has been assessed at preliminary design stage.

10.106 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.

10.107 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.

10.108 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

10.109 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.

10.110 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

10.111 During any phases the site manager would ensure that mitigation measures as

identified within this assessment were fully implemented, and that activities were carried

159

out in such a manner as to prevent or reduce effects. The following construction phase-

specific measures would be implemented.

Pollution Prevention Guidance

10.112 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.

10.113 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;

10.114 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.

160

10.115 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

10.116 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

10.117 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 Q100 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.

161

• Where water is designed to pond or flow overland on the site it would be in

accordance with the guidance in CIRIA C635 – Designing for Exceedance, to

ensure that surface ponding / flow does not cause risk to life or property, i.e.

ponding is maintained at road kerb height (100mm) or lower, with low overland

flow velocities.

10.118 Recommendations have been made for flood related emergency response / evacuation

action plans to be incorporated into the Health and Safety Information File for the site and

incorporated into site management procedures.

Monitoring during construction

10.119 It is recommended that monitoring during any construction be undertaken to

demonstrate that the drainage mitigation proposed for construction phase is sufficiently

robust to remove silts and contamination from runoff thus ensuring that there is no impact

to the downstream sensitive receptors.

10.120 The surface water monitoring regime would consist of physico-chemical techniques

which would be used to identify water quality within the site. The water quality sampling

regime should be carried out during the site’s construction and operation.

Monitoring during operation

10.121 Discharges from the airport are subject to consent. To comply with discharge licence

there is a requirement on the operator to undertake water quality analysis on a fortnightly

/ monthly basis (frequency is dependent upon individual consent). Existing licences may

need to be adapted or new licence sought to reflect project proposals prior to

implementation.

10.122 On-going maintenance would be required for the life of the project in order to ensure

that surface water management installed remain effective, and risk of flooding from piped

drainage within the site due to blockage of channels or culverts is negated. As such a

typical maintenance regime would require the following:

• Cyclical maintenance of permanent drainage features installed during the

construction phase, including unblocking of drains and pipelines, removal of silt build-

up from settlement features, clearing of pipe outlet, and checking of any ancillary

structures.

• Cyclical checks of drainage outlets to watercourses to minimise risk of blockage.

10.123 Ensure best practice is adhered to on site and to help avoid pollution release to

watercourses by incorporating NIEA Pollution Prevention Guidance notes into

management policy.

Mitigating Measures – Summary

10.124 Mitigation proposed is summarised in the context of its effect on hydrological and water

quality impacts as follows:

162

• Ensure that any additional car park areas would be located above the Q200 flood

level (with allowance for freeboard) and that there would be means of safe / dry

access and egress from these areas.

• Identification of emergency procedures in the event of a flood at the site.

• Implementation of surface water management to ensure rate and volume of runoff

from any area to be developed would be no greater than or less than the current site,

and provides treatment of runoff.

• Ensure specific construction measures are incorporated during any construction

works, including (but not limited) to:

o Construction in the vicinity of Watercourses

o Spoil Management

o Dealing with contamination present with spoil and excavation arising.

o Dewatering.

• Ongoing monitoring shall be undertaken throughout the operational life of the

development in accordance with the relevant discharge consent licences.

• Ongoing monitoring and maintenance of the site drainage arrangements.

Residual Effects

10.125 The following table details the predicted mitigated impact magnitude, and associated

significance as a function of the matrix stated in Table 10.4, of all receptors previously

identified as having an unmitigated significance greater than neutral.

Receptor Receptor

Sensitivity Potential Effect Magnitude of Mitigated Effect

Mitigated Significance


High Pollution due release of silt / suspended solids, oils, fuels and chemicals.

Any construction phase to implement surface water control measures to prevent pollution of watercourses by contaminated runoff containing silts, oil, or chemicals.

Design of surface water management during operational phase to be designed to meet requirements of licensed discharge consent.

Surface water management to incorporate continuous sampling regime to identify and contain potential spill / contaminated runoff from proposed aircraft waiting area.

Negligible Effect / Beneficial Effect

Neutral


Any development to be limited to those areas unaffected by fluvial floodplains.

No Effect

Neutral

163

Receptor Receptor




Any development to be limited to those areas unaffected by fluvial floodplains. No fluvial floodplains have been identified within the site boundary.


Neutral


Any additional surface runoff generated by site development will be subject to consent, with attenuation measures implemented as necessary.

Negligible Effect

Neutral

Kinnegar Water

Tillysburn SLNCI



Medium Pollution due release of silt / suspended solids, oils, fuels and chemicals.

Any construction phase to implement surface water control measures to prevent pollution of watercourses by contaminated runoff containing silts, oil, or chemicals.

Design of surface water management during operational phase to be designed to meet requirements of licensed discharge consent.

Surface water management to incorporate continuous sampling regime to identify and contain potential spill / contaminated runoff from proposed aircraft waiting area.


Neutral



No Effect

Neutral




Neutral


Any additional surface runoff generated by site development will be subject to consent, with attenuation measures implemented as necessary.

Neutral

164

Receptor Receptor



Negligible Effect

Proposed changes to the site

High Flooding Parts of areas identified for potential re-development have been assessed as being lower than the Q200 coastal flood level. These areas are not considered to be directly linked to the coastal floodplain via surface flow routes.

Conveyance of floodwaters via the existing drainage systems will be limited due to presence of non-return valves on the outlets.

A 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.

Neutral

Table 10.9 - Magnitude and Significance of Effects to Receptors

Cumulative Effects

10.126 The hydrological setting of the site comprises the catchments of the watercourses

affecting the site, Kinnegar Water and Conns Water, and their respective tributaries.

There are no committed developments identified by the Schedule of Committed

Developments provided (Appendix 2.1: Applications within 5km of GB BCA) that lie within

the upstream catchments, yet to be commenced and likely to affect the GB BCA site.

10.127 Lands downstream and to the north of the site (i.e. the sea), can and will have no

cumulative effect on or with the GB BCA site.

10.128 The Connswater Community Greenway is a major project being carried out by Belfast

City Council, Rivers Agency and the Connswater Community Greenway group. The

works include the improvement and restoration of five kilometres of watercourse including

reaches of the Connswater, Loop and Knock Rivers; located between Victoria Park and

Cregagh Glen. The scheme will provide improvements to water quality within the

respective watercourses and would therefore be considered as having a beneficial water

quality impact on the respective receiving catchments.

10.129 Therefore, cumulative effects are not a consideration.

165

Statement of Significance

10.130 This assessment demonstrates the potential impacts of the ‘project’ upon the local

hydrological setting including local floodplains. It summarises the relevant legislation and

guidance and provides appropriate baseline information, enabling the potential effects to

be identified.

10.131 Aspects of the design, construction and operation of the ‘project’ that may potentially

impact on the receiving surface water environment have been identified and the

pathways for impacts assessed. It has been determined that without mitigation the

‘project’ has the potential to cause adverse impacts of major significance.

10.132 Mitigation provided includes (but is not limited to):

• Avoidance based on baseline constraints mapping;

• Design of site elements to minimise impact on the surface water environment and

floodplain;

• Implementation of a surface water drainage plan;

• Construction phase pollution prevention procedures.

10.133 Mitigation provided 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 to deal with construction

runoff in addition to construction phase pollution prevention procedures;

• Implementation of an emergency response / evacuation plan in the event of a

coastal flood event.

10.134 Monitoring / validation of the mitigation methods will be provided through

physicochemical water quality monitoring, which will validate the performance of the

pollution prevention measures.

10.135 Implementation of the mitigation proposed eliminates or reduces the potential

significance to all receptors to neutral; therefore the ‘project’ is considered acceptable in

terms of its impact on the receiving hydrological environment.

References

10.136 The following information resources have been used to inform this assessment;

• The Strategic Flood Map (Northern Ireland) - Rivers & Sea; Department of Agriculture and

Rural Development Rivers Agency (2008); http://212.147.136.137/floodmaps/main.aspx

• Flood Estimation Handbook & Associated Software Version 3; Centre for Hydrology and

Ecology (CEH)-Wallingford (2009)

• Chronology of British Hydrological Events; Frank M Law, Andrew R Black, Robert M J

Scarrott, John B Miller and Adrian C Bayliss (2010);

http://www.dundee.ac.uk/geography/cbhe/

• HiFlows-UK; Environment Agency (2010); http://www.environment-

agency.gov.uk/hiflows/91727.aspx

166

• Flood Estimation for Small Catchments - Institute of Hydrology. Report No IH124,

Wallingford (1994).

• Flood Studies Report - NERC, HMSO (1974)

• Estimation of Flood Peaks in Northern Ireland Rivers from Catchment Characteristics -

Rivers Agency Design Note; DARD Rivers Agency (Unknown)

• River Basin Plan Interactive Map; Northern Ireland Environment Agency (2010)

http://maps.ehsni.gov.uk/wmuviewer/

• North Eastern River Basin District Management Plan Summary; Northern Ireland

Environment Agency (2009)

• GQA Chemical Classification System - Northern Ireland Environment Agency (2009)

http://www.ni-environment.gov.uk/water/quality/rivers/river_results/gqachemexpln.htm

• GQA Biological Classification System - Northern Ireland Environment Agency (2009)

http://www.ni-environment.gov.uk/water-home/quality/rivers/river_results/gqabiolexpln.htm

• River Monitoring Results - Northern Ireland Environment Agency (2009) http://www.ni-

environment.gov.uk/water-home/quality/rivers/river_results.htm

• Drainage (Northern Ireland) Order – OPSI (1973).

• CIRIA Culvert Design Guide Report No. C168; Construction Industry Research and

Information Association, London (1997)

• CIRIA Culvert Design and Operation Guide Report No. C689; Construction Industry

Research and Information Association, London (2010)

• CIRIA Sustainable Drainage Systems – Hydraulic, Structural and Water Quality Advice

Report No. C609; Wilson, S., Bray, R and Cooper, P. (2004).

• CIRIA Control of Water Pollution from Linear Construction Projects, Report No C648,

Construction Industry Research and Information Association, London (2006).

• CIRIA. Control of Water Pollution from Linear Construction Projects. Site guide. Report No

C649, Construction Industry Research and Information Association, London (2006).

• CIRIA The SUDS manual, Report No C697, Construction Industry Research and

Information Association, London (2007).

• Highways Agency. Design Manual for Roads and Bridges (DMRB) Volume 4, Section 2:

Drainage. HMSO, London (2006).

• UK Mapped Climate Averages

http://www.metoffice.gov.uk/climate/uk/averages/ukmapavge.html

• Conns Water Greenway http://www.communitygreenway.co.uk/project/about-connswater-

community-greenway

Documents

S10 Hydrology & Drainage FINAL - Planning Service · • Water Supply (Water Quality) Regulations ... Assessment Methodology 10.29 This hydrology assessment has been undertaken using