CH 7 Ground conditions 310513

Chapter 7

Ground conditions

7

Kingsmere Phase 2 Countryside Properties (Bicester) Ltd Chapter 7: Ground conditions

Terence O'Rourke Ltd 180601U/ May 2013

7 Ground conditions

Introduction

7.1 This chapter of the Environmental Statement (ES) assesses the potential effect of the proposed development on the ground conditions and potential contamination at the Application Site. In particular, it identifies the current ground conditions at the Application Site, including potential contamination risks and considers the likely significance of potential effects of the proposed development on these conditions. It also considers the potential effects on ground conditions, geological resources, human health and controlled water receptors during the construction and post-construction phases of the proposed development. Where appropriate, measures to prevent, minimise or control those effects are presented together with an assessment of residual effects following the adoption of those measures.

7.2 This chapter, together with its associated figures and appendices, is not intended to be read as a standalone assessment and reference should be made to the rest of this ES.

7.3 This chapter was produced by WSP Environment and Energy Limited (WSP).

7.4 Table 7.1 lists the references and data sources used within this chapter.

Table 7.1: References and data sources

7.1 Part IIA of the Environmental Protection Act 1990,

7.2 Section 57 of the Environment Act 1995

7.3 Contaminated Land Statutory Guidance, Department for Environment, Food and Rural Affairs (DEFRA), April 2012

7.4 National Planning Policy Framework 2012

7.5 Non-Statutory Local Plan, Cherwell District Council, 2011

7.6 Contaminated Land Regulations (CLR 11) Model Procedures for the Management of Land Contamination, Environment Agency (EA) and DEFRA, 2004

7.7 Contaminated Land Risk Assessment – A Guide to Good Practice, CIRIA (C552), 2001

7.8 Contaminated Land Exposure Assessment (CLEA), EA, 2003

7.9 European Parliament and the Council framework for Community action in the field of water policy Directive 2000/60/EC October 2000

7.10 Environmental Quality Standards Directive 2008/105/EC

7.11 UK Drinking Water Quality Standards 2000 (Amended 2004)

7.12 Envirocheck Report (ref. 41494200_1_1),Landmark Information Group,September 2012

7.13 Kingsmere Bicester, Phase 2 Combined Phase I & Phase II Geo-Environmental Assessment Report, Report reference 00028453/001, WSP, December 2012

Legislation and policy

Legislative framework

7.5 Legislation and guidance on the assessment of contaminated Sites is provided under Part IIA of the Environmental Protection Act (EPA) 1990 (Ref. 7.1), as introduced by Section 57 of the Environment Act 1995



(Ref. 7.2). Further guidance on implementation of Part IIA requirements is provided by the Department for the Environment, Food and Rural Affairs (DEFRA), Contaminated Land Statutory Guidance (DEFRA, 2012) (Ref. 7.3).

7.6 The presence of contaminated materials on a site is generally only of concern if an actual or potentially unacceptable risk exists. Within the context of current UK Legislation (Ref. 7.1), the interpretation of a “significant risk” is termed to be one where:

“Significant harm is being caused or there is a significant possibility of such harm being caused, (where harm is defined as harm to health of living organisms or other interference with the ecological systems of which they form a part and, in the case of man, includes harm to his property); and/or, significant pollution of controlled waters is being caused.”

7.7 Criteria for assessing the significance of the effects and residual effects that may arise from land contamination have been produced with reference to technical guidelines from DEFRA, the Environment Agency (EA), the Scottish Environmental Protection Agency (SEPA) and the Scotland and Northern Ireland Forum for Environmental Research (SNIFFER).

7.8 The contaminated land regime set out in the EPA 1990 and its accompanying regulations deal with the existing condition of land. However, the remediation of contamination from historic land uses is managed through the planning regime. The local planning authority (LPA) may require remediation works to be undertaken as part of the development of a site. These works usually encompass site investigation, consultation and remediation works/risk management.

National Planning Policy Framework

7.9 The National Planning Policy Framework (NPPF) (Ref. 7.4) is informed by the contaminated land regime set out in the EPA 1990 (as amended) and its accompanying Regulations which deal with the existing condition of land. The NPPF states the following in relation to ground conditions and contamination:

“The planning system should contribute to and enhance the natural and local environment by: protecting and enhancing valued landscapes, geological conservation interests and soil, preventing both new and existing development from contributing to or being put at unacceptable risk from, or being adversely affected by unacceptable levels of soil, air, water or noise pollution or land instability; and remediating and mitigating despoiled, degraded, derelict, contaminated and unstable land, where appropriate”.

“As a minimum, after remediation, land should not be capable of being determined as contaminated land under Part IIA of the Environmental Protection Act 1990”



Local planning policy

Non-Statutory Cherwell Local Plan 2011

7.10 Cherwell District Council (CDC) is currently in the process of preparing its Local Development Framework (LDF). Once adopted, the LDF will act as planning policy for the district for the period up to 2026. However, in the interim, CDC has issued a Non Statutory Local Plan 2011 (Ref. 7.5) for the purposes of development control.

7.11 EN17 Contaminated Land states:

“Development on land which is known or suspected to be contaminated will only be permitted if: (I) adequate measures can be taken to remove any threat of contamination to future occupiers of the Site and (II) the development is not likely to result in contamination of surface or underground water resources”

Guidance

7.12 Legislation and guidance on the assessment of contamination acknowledges the need for a tiered, risk based approach, underpinned by a Conceptual Site Model. This is recommended in DEFRA/the Environment Agency’s CLR 11 (Ref. 7.6) and in the Construction Industry Research and Information Association (CIRIA) publication 552 ‘Contaminated Land Risk Assessment – A Guide to Good Practice’ (Ref. 7.7) as:

• Development of the specific Conceptual Site Model (Stage 1) • Assessment of Site investigation results against Soil Guideline Values

(SGVs) or Generic Assessment Criteria (GAC) (Stage 2) where available and appropriate as derived by Generic Quantitative Risk Assessment (GQRA)

• Assessment of Site investigation results against Site Specific Assessment Criteria (SSAC) (Stage 3) as derived by Detailed Quantitative Risk Assessment (DQRA)

• SGVs are derived and published by an authoritative body. GAC can be derived by third parties by following the technical UK CLEA guidance and methodology. They take into account generic assumptions about the characteristics of contaminants, pathways and receptors and are designed to be protective in a range of defined conditions. SSAC are derived at a further tier of assessment and use Site specific ground condition, pathway and receptor information to reflect the proposed development in more detail and in many cases reduce the overall conservatism of the assessment

7.13 Contaminated land assessments are based upon the Contaminated Land Exposure Assessment (CLEA) model released by DEFRA (Ref. 7.8). This assesses risk to human health and has a series of SGV for individual contaminants. For contaminants where no SGV has been issued by DEFRA reference is made to the GAC.

7.14 Controlled water quality assessments are based on the Water Framework Directive (WFD) (Ref. 7.9) and there are a number of guideline quality indicators in current use. For surface water,



concentration limits called Environmental Quality Standards (EQS) have been assigned to dangerous substances to control occurrence and avoid harmful effects. The EQS have been taken from the Environmental Quality Standards Directive, 2008/105/EC (Ref. 7.10). For groundwater, guideline values have been designed as standards for the supply of drinking water, as part of the UK Water Supply (Water Quality) Regulations 2000 (and amendments) and Private Water Supplies Regulations (2009) (Ref. 7.11).

Methodology

Scope of the assessment

7.15 As detailed in the environmental impact assessment (EIA) scoping report (included in technical appendix A), the following key issues require consideration in the ES:

• Potential for health effects due to contact with contaminants during construction

• Mobilisation of contaminants into the water environment during construction

• Potential for health effects due to contact with contaminants post-construction (users of gardens and open spaces)

• Potential implications on the presence of invasive plant species

Extent of the study area

7.16 The study area for the desk-based research extended to 500m from the Application Site’s boundary, except for water abstractions where the radius extended to 1km.

Method of baseline data collection

7.17 In order to assess issues identified above, a desk study has been undertaken of the Application Site and surrounding area. The desk study includes:

• An assessment of the current and historical land uses on and surrounding the Application Site from historical and current Ordnance Survey maps and aerial photography;

• An assessment of the sensitivity of the Application Site location as determined by factors such as hydrogeology, proximity of watercourses, neighbouring land use, ecologically sensitive uses, geology etc. from sources such as current Ordnance Survey maps, CDC, the EA, British Geological Survey boreholes and maps and Landmark Information Group Limited.

7.18 The Contaminated Land Officer at CDC and the EA were contacted in regard to providing details of the following pertinent information:

• Whether there are any environmental issues associated with the Application Site, specifically anything that could have led to potential contamination of soil or groundwater either beneath the Application Site or in the surrounding area;

• Whether there have been any soil or groundwater remedial works carried out at the Application Site or within the surrounding area.



7.19 The planning department of CDC was contacted with regard to providing information relating to any planning applications related to the Application Site that may contain environmentally pertinent information in the application or responses.

7.20 Landmark Information Group Limited (Ref 7.12) as commissioned to provide information and details of:

• History of pollution incidents within 500m of the Application Site boundary

• Licensed surface water and groundwater abstractions within 1km of the Application Site

7.21 Analysis of the significance of potential environmental risks identified in the context of the proposed Application Site uses the source-pathway-receptor pollutant linkages approach.

7.22 A walkover survey was undertaken by a Senior Environmental Consultant from WSP as part of the intrusive investigation undertaken in October 2012 (report reference 00028453/001) (Ref 7.13) and information obtained from the walkover and intrusive investigation has been considered within this assessment.

7.23 The ground investigation comprised eight rotary boreholes to 8.00m bgl each with dedicated groundwater and ground gas monitoring wells, excavation of 23 trial pits to a maximum depth of 3.6m bgl and indicative in-situ soakaway tests performed within four trial pits. Suitable soil and groundwater samples were taken by WSP and analysed for a range of determinands by the Environment Agency’s Monitoring Certification Scheme (MCERTS) and the United Kingdom Accreditation Service (UKAS) accredited laboratory of Alcontrol in Hawarden.

7.24 The results of the ground investigation were assessed with respect to a residential with gardens land-use scenario to establish whether the Application Site was deemed suitable for use in its current state or whether mitigation measures would be required to address potential constraints.

Significance criteria

7.25 As discussed above, the presence of contaminating substances on a Site is generally only of concern when “significant harm is being caused or there is a significant possibility of such harm being caused…” (Ref. 7.1)

7.26 The potential for harm to occur requires three conditions to be satisfied:

• The presence of substances (potential contaminants / pollutants) that may cause harm (the source of pollution)

• The presence of a receptor which may be harmed, (e.g. the water environment or humans, buildings, fauna and flora) (the receptor)

• The existence of a linkage between the source and the receptor (the pathway)

7.27 Current UK guidance advocates the use of a conceptual risk assessment model when assessing the potential for harm to occur. The three conditions detailed above comprise the basis of this approach,



such that without each of the three elements (source, pathway and receptor) there can be no contamination risk. Therefore, the presence of measurable concentrations of contaminants within the ground and subsurface environment does not automatically imply that a contamination problem exists, since the contamination must be defined in terms of pollutant linkages and unacceptable risk of harm. The conceptual model is illustrated in Figure 7.1.

Figure 7.1: Conceptual model

SOURCE

e.g. s ur face fue lsp i llage PATHWAY

e.g. in fi ltr ation

RECEPTOR

e.g. groundwater

7.28 There are no known published standard criteria for assessing the significance of the potential effects that may arise from land contamination. However, where appropriate, the significance of the effect (where a contamination risk has been identified) has been determined from criteria developed from best practice techniques and professional judgement, utilising published guidance and legislation, e.g. EA R&D publication CLR11 (2004) ‘Model Procedures for the Management of Land Contamination’ (Ref 7.6), in order to determine soil and contamination related issues that have the potential to cause harm. Measures of the magnitude or scale of effect and the importance or sensitivity of the resource affected has also been used.

7.29 Valuation of the receptor

7.30 The criteria set out in table 7.2 have been used for the valuation of receptors.

Table 7.2: Criteria for assessing valuation of receptors

Value Criteria Example Receptors

High Generally, but not exclusively, Sites of international and national importance and resource/features which are unique and if lost cannot be replaced or relocated. Receptors of greatest sensitivity.

Human Health, including, construction and maintenance workers, future Site users/occupants and third party neighbours.

Medium Features of important consideration at a regional or district scale.

Mineral Resources

Low Features important at a local scale. Soils

Impact Magnitude (the extent of change i.e. deviation from the baseline)

7.31 Contamination has been assessed by the identified presence of specific potential sources of contamination, pathways and sensitive receptors. The categories in table 7.3 are used in assessing the impact magnitude.



Table 7.3: Criteria for assessing impact magnitude

Magnitude Criteria

Very substantial / substantial

Significant, long term deterioration/improvement in local conditions or circumstances, i.e.: Construction phase release of contaminants which causes a significant impact on identified receptors; Elimination and/or mitigation of existing large scale effects upon identified receptors during the operational phase.

Moderate Readily apparent change in conditions or circumstances, including long term effects, i.e. Minor release of contaminants during the construction phase; Elimination and/or mitigation of limited existing effects upon identified receptors during the operational phase.

Slight Perceptible change in conditions or circumstances, generally in the short term, i.e. Limited, temporary contaminant release associated with construction phase; Temporary creation/elimination of pollution pathways during the construction phase.

Negligible where no discernible effect is expected as a result of the proposed development on the identified sensitive receptors

Limitations and assumptions

7.32 For the purposes of the assessment of effects during construction, the effects detailed are based on the most significant effects that the contaminants identified during site investigations are likely to have on the receptors identified and represent a conservative approach using a worst case scenario.

Baseline conditions

Site history

7.33 A study of historic Ordnance Survey (OS) maps obtained from Landmark Information Group (Ref. 7.12) has been undertaken to identify any potentially contaminative former land uses on, or within influencing distance of the Application Site. A summary of pertinent features on the Application Site and within 500 m of the Application Site are provided in tables 7.4 and 7.5 respectively.



Table 7.4: Summary of on-site land uses

Land Use On-site Dates

Agricultural fields including a number of footpaths traversing the land. Particular areas of interest include: • An Old Windmill is indicated in the north western

region of the Application Site, • An old quarry in the north-eastern part of the

Application Site. • A wind pump shown in the south-eastern portion of

the Application Site close to Whitelands Farm buildings.

• A quarry is present right on the north-western boundary of the Application Site which may encroach slightly onto the Application Site itself.

Pre 1881-present Pre 1881-pre 1899 Pre 1881-pre 1922 Pre 1967-pre 1984 Pre 1899-pre 1967

Table 7.5: Summary of surrounding land uses

Land Use Surrounding Application Site

Distance / Direction Dates

Whitelands Farm 40 m south east Pre 1875-present

Whitelands Cottages (now demolished) and a ‘Pump’

200m east Pre 1881-recent

Quarry 20 m north west Pre 1899-pre 1967

Housing estate 50m north 200m north east

Pre 1984-present Pre 1967-present

Regulatory databases

7.34 Table 7.6 provides an overview of the environmental data, from several regulatory sources that is detailed within the Envirocheck Report (Ref 7.12). A full copy of the Envirocheck Report is provided for reference in Technical Appendix D – Ground conditions.

Table 7.6: Summary of regulatory data

Information On-Site Within 500m of the Application Site

Sources of Information

Discharge consents

None found 2 – Only one consent remains active. It relates to sewage discharges by Thames Water Utilities Ltd to Gagle Brook approximately 340 m south west of the Application Site

Envirocheck

Local authority pollution prevention an controls

None found None found Envirocheck

Historic landfill Sites

None found*

None found Envirocheck

Licensed waste management facilities


Recorded landfill Sites


Pollution incidents to controlled waters

None found 8 – The closest incident to the Application Site was approximately 220 m south

Envirocheck



Table 7.6: Summary of regulatory data

Information On-Site Within 500m of the Application Site

Sources of Information

west. In each case the receiving water is not indicated but the severity is noted to be Category 3 minor incident.

Trade directory information

None found 3 – Two of these relate to domestic cleaning services and the third relates to electronic component manufacture and distribution.

Envirocheck

Sensitive land uses

The Application Site is indicated to be within a Nitrate Vulnerable Zone

Nitrate Vulnerable Zone Envirocheck

BGS recorded mineral Sites

None found 1 – Located approximately 35 m north west of the Application Site is a historic limestone quarry which has now ceased operation.

Envirocheck

*It is not known if the former quarries within the north east and north west of the Application Site have been in-filled.

Regulatory search enquiries

7.35 The Contaminated Land Officer at CDC was contacted for environmentally pertinent information. The response indicates that the north western corner of the Application Site has been considered within the scope of the contaminated land strategy.

Radon and ground gas

7.36 The ground conditions are not considered by the Health Protection Agency to present a radon risk as less than 1% of homes are above the radon actions levels and no radon protection measures are necessary in the construction of new dwellings.

7.37 Ground gas monitoring has been completed in all monitoring standpipes since the completion of the intrusive investigation. A brief summary of the monitoring is provided below:

• Methane was recorded between 0% and 0.1% v.v • Carbon dioxide concentrations were recorded between <0.1% and

1.7% v.v • Oxygen concentrations ranged between 18.2% and 20.8% v.v • Ground gas flow was recorded between <0.1 litres per hour (l/hr) and

0.1 l/hr

7.38 The exploratory hole plan is presented as figure 7.2.



Geology and hydrogeology

7.39 In accordance with the British Geological Survey (BGS) 1:50,000 Map Sheet 219 Buckingham (Solid and Drift) published in 2002, the Application Site is indicated to be underlain by the geological sequence set out in table 7.7.

Table 7.7: Summary of published geology

Geological Unit Description Aquifer Status*

Cornbrash Formation Rubbly grey to brown limestone Secondary (A†)

Forest Marble Formation Grey mudstone with beds of limestone Secondary (A†)

Notes: * - Taken from the Environment Agency Website † - Secondary (A) is defined by the Environment Agency as permeable layers capable of supporting water supplies at a local rather than strategic scale, and in some cases forming an important source of base flow to rivers. These are generally aquifers formerly classified as minor aquifers.

7.40 The above geological sequence has been confirmed by the intrusive investigation at the Application Site undertaken by WSP. A summary of the ground conditions encountered at the Application Site is provided in table 7.8.

Table 7.8: Encountered ground conditions

Strata Depth range to top of stratum (m bgl)

Depth to base of stratum (m bgl)

Brief Description

Topsoil Ground level 0.2 to 0.6 Topsoil was typically dark brown slightly sandy slightly gravelly silty clay with frequent rootlets. The gravel fraction typically comprised fine to medium subangular limestone.

Cornbrash Formation

0.2 to 0.8 1.0 to 3.0 Orange brown clayey to very clayey sandy fine to coarse subangular limestone gravel. Locally the Cornbrash Formation was recorded as a stiff to very stiff orange brown, slightly sandy, gravelly to very gravelly clay. The gravel fraction typically comprised fine to medium subangular limestone and lithorelics.

Forest Marble Formation

1.0 to 3.0 > 8.1* Alternating horizons of clay/mudstone and limestone. The clay horizons were generally recorded as a very stiff to hard, dark bluish grey, silty clay. In places the mudstone had not weathered back to clay and so was recorded as an extremely weak mudstone. The limestone horizons were generally recorded as a medium strong to strong, light grey fine grained limestone.

* Base not proven

7.41 With reference to the published geological information and confirmed by the intrusive investigation, superficial deposits were absent and the Application Site is underlain by strata of the Cornbrash Formation.



Overlying Kellaways Clay Member stratum may be encountered in the far southern region of the Application Site.

7.42 A record of an exploratory hole progressed at Whitelands Farm to the south east of the Application Site has been obtained from the British Geological Survey. The borehole record indicates that topsoil may be present to a depth of 0.3m with alternating horizons of limestone and clay proven to a depth of approximately 42m. The record also indicated that groundwater was encountered at approximately 7.6m below ground level.

7.43 Minor groundwater seepages were noted during the intrusive investigation in several exploratory holes at depths of between 0.6m bgl and 1.9m bgl.

7.44 Groundwater at the Application Site was encountered at elevations of between 68.8m Above Ordnance Datum (AOD) and 77.2m AOD during drilling within the Forest Marble Formation. In several instances within the central region of the Application Site, within BH704, BH705 and BH706, groundwater was observed to be under artesian pressure and rose to a maximum height of 1.7m agl (above ground level).

7.45 Subsequent monitoring within the standpipes installed within several exploratory holes recorded groundwater between 0.5m and 3.0m bgl. Groundwater elevation is indicated to be between 80.70m AOD in the north of the Application Site and 72.70m AOD in the south western region. From the monitoring undertaken it appears that groundwater follows the topography and flows to the south east.

7.46 The EA website indicates that the aquifer within the Cornbrash Formation (known as the Bicester-Otmoor Cornbrash Formation aquifer) is part of the Thames River Basin District. Current quantitative quality is good and the current chemical quality is poor. This status is expected to remain during the next cycle in 2015.

Ground hazards

7.47 With reference to the British Geological Survey ground hazard database, the Application Site is located within an area where the potential risks set out in table 7.9 may be present.

Table 7.9: Summary of published ground hazards

Ground Stability Hazard Hazard Potential

Collapsible ground stability hazard No hazard to very low

Compressible ground stability hazard No hazard to moderate

Ground dissolution stability hazard No hazard to very low

Landslide ground stability hazard Very low

Running sand ground stability hazard No hazard to low

Shrinking or swelling clay stability hazard

No hazard to moderate



Groundwater abstractions

7.48 There is a record of a groundwater abstraction within the south-eastern portion of the Application Site for general farming and domestic use. This abstraction appears to be located in the position of the wind pump adjacent to Whitelands Farm noted within the historic maps.

7.49 There are no other groundwater abstractions within 1km of the Application Site’s boundary. The pump at Whitelands Cottages shown on the historic maps is not recorded as a licenced abstraction point.

Hydrology

Surface water features

7.50 Surface water features located on or within 500m of the Application Site are listed in table 7.10.

Table 7.10: Summary of published ground hazards

Surface Water Feature Distance (m) Direction Water Quality

Land drain Adjacent North east N/A

Land drain 200 South west N/A

Gagle Brook 250 South west Not classified

7.51 The Application Site is not within an area at risk of flooding from rivers or seas as defined by the EA. The results of the flood risk assessment (FRA) are reported within Chapter 12: the water environment.

Surface water abstractions

7.52 There are no surface water abstractions recorded on or within 1km of the Application Site.

Preliminary conceptual site model

7.53 Based on an assessment of the above data a preliminary conceptual site model (CSM) has been developed and is shown in Table 7.11. The CSM is applicable for both during and post-construction.

Table 7.11: Preliminary Conceptual Site Model

Potential Contaminant Sources

Associated Contaminants Potential Migration Pathways

Sensitive Receptors

On-Site

Human health inhalation of ground gases Ingestion of soil and dust Direct contact with soil

Future Site users Construction and maintenance staff

Made Ground, potential areas of burning and agricultural use

Metals (such as naturally occurring arsenic) Asbestos from former farm buildings Polycyclic aromatic hydrocarbons (PAHs) from potential areas of fallow land burning; Ground gas Herbicides and pesticides

Controlled waters Leaching into groundwater and lateral migration

Groundwater: secondary (A) aquifer Gagle Brook

Off -Site

In-filled quarry and Metals and Inorganics (such as Migration of Adjacent Site users



Table 7.11: Preliminary Conceptual Site Model

Potential Contaminant Sources

Associated Contaminants Potential Migration Pathways

Sensitive Receptors

Made Ground

pH and sulphate) and asbestos Total petroleum hydrocarbons (TPH) Polycyclic aromatic hydrocarbons (PAHs) Semi volatile organic compounds (SVOCs) and ground gas.

groundwater or gas onto Site

Construction and maintenance staff Groundwater and Secondary (A) Aquifer

7.54 A total of 18 samples, comprising six of topsoil and 12 of the Cornbrash Formation, were analysed for a range of metal, inorganic and organic determinands during the investigation.

Assessment of the analytical results – human health

Metals and inorganics

7.55 With the exception of one sample from the southern region of the Application Site (TP713 at 0.5m depth), none of the samples tested recorded determinands concentrations above the relevant GAC/SGV.

7.56 TP713 recorded an elevated arsenic concentration of 45.6 mg/kg which exceeds the published SGV of 32 mg/kg. However, elevated concentrations of arsenic have not been recorded elsewhere across the Application Site, such that it is considered that the exceedance is an isolated incident and based on knowledge of the area, it is assumed to be naturally occurring.

7.57 No asbestos was detected in the seven samples screened.

Organics

7.58 Concentrations of organic determinands including total petroleum hydrocarbons (TPH), Criteria Working Group (CWG), polycyclic aromatic hydrocarbons (PAH), semi-volatile organic compounds (SVOC) and volatile organic compounds (VOCs) were not detected above the relevant GAC.

Herbicides and pesticides

7.59 All levels of herbicides and pesticides, including persistent organic pollutants (POPs) were below their respective laboratory limits of detection.

Assessment of the analytical results – controlled waters

7.60 Groundwater samples were collected and submitted for analytical laboratory testing. The results indicate that the majority of determinands are below the GAC for groundwater/drinking water. Heavy-end petroleum hydrocarbons were recorded in groundwater samples obtained from the north western part of the Application Site but on the basis of a detailed quantitative risk assessment (DQRA) completed for



the adjacent development (Phase 1 development area), the risk to controlled waters is considered to be low.

Assessment of ground gas

7.61 Ground gas monitoring has been undertaken within the monitoring standpipes and indicates that the ground gas regime (potential to generate carbon dioxide, methane, oxygen, carbon monoxide and hydrogen sulphide) at the Application Site can be characterised as Very Low Risk (characteristic Situation 1) in accordance with CIRIA 665. Based on the results of the assessment no special gas protection measures are required.

Future baseline

7.62 If the proposed development were not to proceed, it is anticipated that any identified contamination would remain in-situ. As no significant current sources of contamination have been identified on or off-Site, it is not anticipated that ground conditions would worsen.

Assessment of effects, mitigation and residual effects

7.63 It is considered that the effects, mitigation measures and residual effects identified in the following section are common for the entire Application Site and therefore applicable across all development scenarios as referred to in Chapter 2, unless otherwise stated.

Effects during construction

Effect of exposure to contamination on construction staff

7.64 Construction workers may be exposed to contaminants that are present in any soil, particularly within the quarried areas or shallow groundwater during earthworks exercises or general excavations.

7.65 The length of time of direct exposure will be limited to the duration of site works in which construction workers are directly involved. However, any health effects from potential contamination could have a medium to long term effect.

7.66 The sensitivity of construction and maintenance workers is high and the magnitude of change, prior to mitigation, small. Therefore, there is likely to be a direct, permanent moderate adverse effect, which would be significant on construction and maintenance workers prior to the implementation of mitigation measures.

Effect on third party occupants and properties

7.67 Works that involve the excavation of soil may potentially release contaminants to the atmosphere, e.g. contaminated dust, asbestos fibres, or will encourage migration of contaminants through groundwater by creating new preferential pathways.

7.68 Third party occupants may be affected by contact with contamination, such as direct contact with soil and groundwater, and inhalation of air-



borne contamination. Any health effects from the possible contaminants could have a medium to long term effect.

7.69 The sensitivity of third party occupants and properties is high and the magnitude of change, prior to mitigation, is small. Therefore, there is likely to be a moderate direct, permanent adverse effect on third party occupants and properties.

Effect on groundwater in the secondary (A) aquifers

7.70 During construction, excavations and other ground works may create preferential pathways for surface water and the potential migration of any contamination from soil or other areas into the underlying Cornbrash Formation.

7.71 Leaks or spills of fuels and lubricants used during the construction process may infiltrate into the ground and migrate into the underlying aquifer. However, the magnitude of any such incidents is likely to be isolated and small.

7.72 The sensitivity of secondary (A) aquifers is medium and the magnitude of change, prior to mitigation, is small. Therefore, there is likely to be a direct, temporary, slight adverse effect on secondary (A) aquifers which is not significant in an EIA context.

Effect on land drains and Gagle Brook

7.73 Any contaminated sediment may enter the surrounding land drains as silt laden surface water run-off and migrate to the Gagle Brook. The brook may also create a pathway transporting contamination downstream.

7.74 Any ecosystems in the land drains and Gagle Brook may be negatively affected by contamination arising from construction practices.

7.75 The sensitivity of the land drains and Gagle Brook is low and the magnitude of change, prior to mitigation, is medium. Therefore, there is likely to be a direct, permanent, long-term slight to moderate adverse effect which is significant prior to the implementation of mitigation measures.

Post-construction effects

Effect of contamination on future site occupants and properties

7.76 Motor vehicle fuel and oil entering the drainage system after spills and leaks could discharge into the groundwater and surface water. Contaminants could then potentially be absorbed by vegetation growing on Application Site that may then be consumed by Application Site occupants. Contaminants in the groundwater could also potentially affect foundations on Application Site which can be aggressively attacked by chlorinated hydrocarbon and sulphur contamination that could occur as a result of these spills. Based on previous experience spills are likely to be small and localised in extent and unlikely to significantly impact sensitive receptors.



7.77 With regard to the locally elevated concentrations of arsenic detected, if the area is to be within residential garden areas, it is recommended that a capping layer of clean topsoil is placed to provide an effective barrier between end users and the shallow soils. The elevated concentrations of arsenic are below the GAC for commercial or public open space so further assessment is recommended once the master plan is finalised.

7.78 Areas of gardens and soft landscaping at the Application Site will be constructed using material which has been validated to ensure it is suitable for use.

7.79 The sensitivity of future Application Site occupants is high and the magnitude of change, prior to mitigation, is negligible. Therefore, there is likely to be a negligible effect on future Application Site occupants and properties, which is not significant in EIA terms.

Effect on maintenance staff

7.80 If electrical sub-stations or flammable gas stores make up part of the proposed new development as they do at Kingsmere Phase 1, maintenance staff may be exposed to a build-up of volatile vapours if the stores are improperly ventilated.

7.81 The sensitivity of maintenance staff is high and the magnitude of change, prior to mitigation, is small. Therefore, there is likely to be a moderate adverse effect on construction workers, which will be significant in the EIA context prior to the implementation of mitigation measures.


7.82 Motor vehicle fuel and oil entering the drainage system after spills could discharge into the groundwater. However, any spills are likely to be small and isolated.

7.83 The sensitivity of groundwater in the secondary (A) aquifers is medium and the magnitude of change, prior to mitigation, is small. Therefore, there is likely to be a direct, short-term slight adverse effect on groundwater in the secondary (A) aquifers, which is not considered to be significant in EIA terms.

7.84 Interceptors will be considered for all areas where vehicles will be permitted, to intercept contaminants that could be sourced from vehicle fuel and oils spills, prior to drainage discharge. The use of interceptors will ensure no change to groundwater in the secondary (A) aquifers.

Effect on third party properties and occupants

7.85 Motor vehicle fuel and oil entering the drainage system after spills could discharge into the groundwater and surface water, and potentially migrate to third party properties. Any spills are likely to be small and localised in extent and based on previous experience unlikely to significantly impact sensitive receptors.

7.86 The sensitivity of third party properties and occupants is high and the magnitude of change, prior to mitigation, is small. Therefore, there is



likely to be a direct, temporary, moderate adverse effect on third party occupants and properties, which is significant in EIA terms, prior to the implementation of mitigation measures.

7.87 Interceptor drains may be considered in areas of future vehicle usage to further ensure that any spills do not enter service trenches directly or through groundwater migration.

7.88 The sensitivity of potable water supply is high and the magnitude of change, prior to mitigation, is negligible. Therefore, no effect on potable water supply is expected.

Effect on potable water supply

7.89 The potable water supply on-site may be affected by future vehicle fuel and oil spills entering the service trenches. However, any spills are likely to be small and localised in extent and based on previous experience unlikely to significantly impact sensitive receptors, and the service trenches will be sealed.

Mitigation

Construction

Effect of exposure to contamination on construction staff

7.90 Construction workers will be required to wear personal protective equipment (PPE) such as gloves and dust and ventilation masks to prevent dermal contact and inhalation or ingestion of contaminants. Appropriate Site hygiene and welfare facilities will be provided as per relevant regulations.

7.91 Where necessary, water/dust suppressant will be sprayed onto material being worked to damp down any potentially contaminated dust and prevent it from becoming airborne.

7.92 Care will have to be taken when working around or in excavations, with workers having appropriate training such as confined space training as appropriate.

7.93 A Construction Environmental Management Plan (CEMP) will be implemented that takes into account relevant good site practice with respect to the handling of potentially contaminated material, which will be enforced and monitored throughout the construction phase.

7.94 Good training and supervision of construction and maintenance workers should mitigate any remaining risks – ensuring that they are working in the safest possible manner and correctly following the health and safety measures put into place. It should also give them the confidence to stop work if they feel unsafe.

Effect on third party occupants and properties

7.95 Although the effect on third party occupants is not considered to be significant in EIA terms, standard best practice construction methods will



be employed, as discussed below, which will further reduce the effect to negligible.

7.96 Where necessary, material being worked may be damped down to reduce the potential of any contaminated dust from becoming airborne. Temporary surface water drainage and vehicle wheel washes further reduce the risk of dust generation.

7.97 The CEMP will be implemented, taking into account relevant good Site practice as mentioned previously. The CEMP will be enforced and monitored throughout the construction phase.


7.98 Significant sources of contamination have not been identified on-site and any existing surface water currently infiltrates into the ground. Should any potential areas of contamination be encountered these would be delineated, excavated and appropriately removed from Site to prevent any potential future risks to controlled waters.

7.99 Fuels and lubricants will be stored in appropriate containers in specified areas on-Site with all refuelling occurring within these areas. Spill kits will be kept on-Site at all times in order to react quickly to any spills or leaks.

7.100 In addition all works on-site will be undertaken in accordance with EA Pollution Prevention Guidance (PPG).

Effect on land drains and Gagle Brook

7.101 Appropriate measures for the management of surface water run-off will be implemented taking into account relevant good site practice with respect to provided surface water drainage, runoff collection and prevention of silt entering the surrounding watercourses. It will be enforced and monitored throughout the construction phase and will be detailed within the CEMP.

Post-construction

7.102 The build-up of volatiles, gases and fumes can be prevented by ensuring proper ventilation standards are adhered to for the relevant areas during construction, ensuring equipment is properly maintained, and that staff wear PPE such as face masks if deemed necessary.

7.103 Interceptors will be proposed for all areas where vehicles will be permitted, to intercept contaminants prior to drainage discharge.

Residual effects

7.104 The sensitivity of construction and maintenance workers is high and the magnitude of change, following mitigation, is negligible. Therefore, there is likely to be a negligible effect that is not significant on construction and maintenance workers, following the implementation of mitigation measures.

7.105 The sensitivity of the secondary aquifers is medium and the magnitude of change, following mitigation, is negligible. Therefore, there is likely to be



a negligible effect on groundwater in the secondary (A) aquifers following the implementation of mitigation measures.

7.106 The sensitivity of the land drains and Gagle Brook is low and the magnitude of change, following mitigation, is negligible. Therefore, no significant residual effect is predicted.

7.107 The sensitivity of maintenance staff is high and the magnitude of change, following mitigation, is negligible. Therefore, there is likely to be a direct, temporary, short-term negligible effect on construction workers (not significant) following the implementation of mitigation measures.

7.108 The sensitivity of third party occupants and properties is high and the magnitude of change, following mitigation, is negligible. Therefore, following the implementation of mitigation measures, no effect on third party occupants and properties is anticipated.

Monitoring and follow up

7.109 It is not anticipated that any follow-up or monitoring of the ground conditions will be required post-construction provided the recommended remediation and mitigation measures are implemented for the proposed development.

Cumulative effects

7.110 Individual effects from the soil and groundwater of the Application Site are discussed in detail in this chapter. However, the potential cumulative effects of several surrounding developments also require consideration as summarised below:

• South West Bicester Phase 1 – 1,585 dwellings • South West Bicester Phase 1 – density increase by 100 dwellings • South West Bicester Reserved School Site – 46 dwellings • NW Bicester Eco Development Phase 1: 394 dwellings, a primary

school, a nursery school, an eco pub, 770m2 of local retail units, 2,900m2 of B1 (business) floorspace, a community centre and public open space

• Land off Middleton Stoney Road and Howes Lane: 70,767m2 of B1 / B2 / B3 floor space

• Gavray Drive: up to 500 dwellings, a primary school and public open space

• Bicester town centre: demolition and comprehensive redevelopment to provide a supermarket, a multiplex cinema, a library, 25 retail units, restaurants and cafes, and 19 residential units

• Talisman Road – new generator • Bicester Business Park: 60,000m2 of B1 floorspace and a hotel • Tesco and Bicester Village: a 5,181m2 extension and replacement of

the existing Tesco store on a new site • Graven Hill: 1,900 dwellings, a primary school, a community hall,

public open space, five local shops, a 1,858 m2 grocery store, a hotel / pub / restaurant, 2,160m2 of B1a (office) floorspace, 2,400m2 of B1b (research and development) floorspace, 20,520m2 of B1c and B2 (light and general industry) floorsapce and up to 66,980m2 of B8 (storage and distribution) floor space



7.111 With the exception of the adjacent Kingsmere Phase 1 proposals, no cumulative effects from a soils, groundwater and contamination perspective are predicted.

7.112 It may be assumed that contaminants with the potential to be present in the soil on the Application Site under discussion in this Chapter could be found throughout the overall development area, including Kingsmere Phase 1 development. Therefore, the effects of migration and the precautions and mitigations detailed as necessary in this chapter will be required throughout the overall development area.

7.113 If construction works are carried out at the same time across the overall development area, the potential effects of contamination migration to human health receptors such as third party occupants and properties will be multiplied. However, the mitigation works outlined in this Chapter are considered sufficient to mitigate potential effects from both development on the Application Site and the wider development area and no additional mitigation measures are require above those detailed in this Chapter.

7.114 The removal or remediation of any contaminated material during the construction of all phases of the wider development will have an overall positive cumulative effect on environmental receptors.

7.115 It is not considered that there will be any cumulative effects during the operational phase as, assuming the advised mitigation measures are put into place, no residual effects are expected.

Summary

7.116 An assessment has been undertaken of the likely significant effects of the proposed development on soils, geology and contaminated land at the Application Site, and the potential effects of contamination on the development and other identified receptors.

7.117 Legislation and guidance on the assessment of contaminated Sites are provided under Part IIA of the Environmental Protection Act 1990 and the Environment Act 1995. The potential for harm to occur requires three conditions to be satisfied:

• The presence of substances (potential contaminants/pollutants) that may cause harm (source of pollution)

• The presence of a receptor which may be harmed, (e.g. the water environment or humans, buildings, fauna and flora) (the receptor)

• The existence of a linkage between the source and the receptor (the pathway)

7.118 The proposed mitigation measures aim to remove either the source of contamination or the pathway, thus removing the potential for harm.

7.119 The assessment includes an overview of the findings of a geo-environmental desk study assessment included as Technical Appendix D: Ground conditions.

7.120 Proposed mitigation measures that will be included in the design and CEMP include:



• Appropriate use of PPE and provision of welfare facilities during construction and maintenance

• Education of construction workers of the potential contamination that could be present on Site and appropriate handling techniques

• A reactive Site watching brief to allow rapid identification and risk assessment of any uncovered contamination

• Damping down of dust • Design for drainage around excavations • Implementation of the guidance detailed in the UK Water Industry

Research (UKWIR): Guidance for the Selection of Water Supply Pipes to be used in Brownfield Sites (UKWIR 2010) during the redevelopment of the Application Site to ensure pipe materials will not allow ingress of potential contaminants

7.121 Residual effects post-construction have all been assessed as negligible based upon the Application Site being remediated and constructed to a suitable environmental standard and adequate information being gathered in order to appropriately design foundations, floor slabs and ground gas protection measures.

Kingsmere Phase 2 Environmental Statement Terence O’Rourke

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Figure 7.2 Exploratory hole location not to scale

Site Boundary

Borehole location

Trial Pit location

Window sample location

Additional soakaway tests performed

© Reproduced from the Ordnance Survey map with the permission of the Controller of Her Majesty’s Stationery Office. Licence No. 100048755. Crown Copyright reserved.

Copyright WSP, 2013

Documents

CH 7 Ground conditions 310513