Government Pipelines and Storage System (GPSS) Portfolio – Backford South

LAND QUALITY ASSESSMENT REPORT

 Phase One and Two: Desk Study and Site Investigation

 DIO Project Number: 13199

 Prepared by SKM Enviros for the Ministry of Defence, Defence Infrastructure Organisation, under commission FTS3/ELMG/100

 FINAL

 June 2013

DEFENCE INFRASTRUCTURE ORGANISATION GPSS Portfolio – Backford South LAND QUALITY ASSESSMENT REPORT

 Phase One and Two: Desk Study and Site Investigation

 DIO Project Number: 13199

Task Officer Prepared by SKM Enviros for the Defence Infrastructure Organisation Ministry of Defence, Defence Kingston Road Infrastructure Organisation, under Sutton Coldfield commission FTS3/ELMG/100 West Midlands B75 7RL Tel: 0121 311 3618

MAIN CONTRIBUTORS ANDREW SURDEVAN

Report Issued by: Report Reviewed by: ALAN WHITE CHRIS STEWART

Accepted by Task Officer on behalf of Accepted by Sponsor: Defence Infrastructure Organisation:

SKM Enviros, Enviros House, Shrewsbury Business Park, Shrewsbury SY2 6LG Tel: +44 (0)1743 284800 Fax: +44 (0)1743 245558

The SKM logo trade mark is a registered trade mark of Sinclair Knight Merz Pty Ltd. GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

Contents

Land Quality Statement 1 Introduction 1 Site Description and History 1 Site Sensitivity 1 Potential Sources of Contamination 1 Preliminary Risk Assessment 1 Site Investigation Strategy 2 Investigation Works Undertaken 2 Ground Conditions Identified 2 Summary of Site Investigation Results 2 Updated Risk Assessment 3 Risk Descriptions 3 1. Introduction 4 1.1. Objectives 4 1.2. Methodology 4 1.3. Framework for Contaminated Land Assessment 5 1.4. Structure of this Report 6 2. Site Description 7 2.1. Site Location 7 2.2. Site Layout 7 2.3. Site Operations and Site Use 7 2.4. Surrounding Area 9 2.5. Public Register Information 9 3. Site History 11 3.1. Historical OS Maps 11 3.2. MOD and Other Sources 11 4. Site Sensitivity 13 4.1. Geology 13 4.2. Hydrogeology 13 4.3. Hydrology 13 4.4. Ecology 14 4.5. Site Sensitivity 14

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE i GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

5. Initial Conceptual Site Model and Environmental Risk Assessment 15 5.1. Conceptual Model Outline 15 5.2. Potential Contaminant Sources 15 5.3. Identified Pathways 16 5.4. Identified Receptors 17 5.5. Preliminary Risk Assessment 17 5.6. Summary of Environmental Risks 27 6. Site Investigation Strategy 28 6.1. Scope of Works 28 6.2. Intrusive Works 28 6.3. Analytical Strategy 29 7. Site Investigation Methodology 30 7.1. Supervision 30 7.2. Summary of Works Undertaken 30 8. Summary of Ground Conditions 33 8.1. Ground Conditions 33 8.2. Natural Ground 33 8.3. Visual and Olfactory Contamination in Soils 33 8.4. Groundwater Levels 33 8.5. Visual and Olfactory Evidence of Contamination in Groundwater 34 8.6. Gas Concentrations 34 9. Methodology for Interpretation of Chemical Analysis Data 35 9.1. Generic Assessment Criteria 35 9.2. Hazards to Human Health – Soil Contamination 35 9.3. Potential Contamination of Controlled Waters 36 10. Review of Laboratory Analysis 37 10.1. Chemical Soil Analysis 37 10.2. Summary of Analytical Data 40 11. Updated Environmental Risk Assessment 41 11.1. Updated Risk Assessment Summary 48 12. Overall Land Quality and Suitability for Use 49 13. References 50

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE ii GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

FIGURES Figure 1: Site Location Plan Figure 2: Site Layout, Potential Contaminant Sources and Exploratory Hole Locations Figure 3: Conceptual Site Model Figure 4: Groundwater Contour Plan APPENDICES Appendix A Site Photographs Appendix B Public Register Information Appendix C Historical Maps Appendix D Risk Assessment Methodology Appendix E Exploratory Hole Logs Appendix F Derivation of SKM Enviros Generic Assessment Criteria (GAC) Appendix G Soil Chemistry Data Appendix H Certificate of Analysis – Soil Appendix I TPH Calculation Sheets Appendix J Water Chemistry Data Appendix K Certificate of Analysis - Waters

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE iii GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

Land Quality Statement

Introduction

In August 2012, SKM Enviros (SKM) was commissioned by the Defence Infrastructure Organisation (DIO) to undertake a combined Phase One and Two Land Quality Assessment (LQA) at the Government Pipelines and Storage System (GPSS) ‘Backford South’ facility at Backford, Cheshire.

The objectives of this LQA, are to evaluate potential risks to human health and controlled waters which will allow identification of potential environmental risks for the MOD and support the disposal process for the site. The assessment has been completed on the understanding that the site is to be divested for continued or future commercial / industrial use (as a fuel management facility).

Site Description and History

The 7 hectare site is generally flat with seven 5500m3 fuel storage tanks buried within grass mounds across the western half of the site. The site is currently mothballed, but operated as a fuel pumping station and storage depot between circa 1939 and the early 1990s. Infrastructure remains in situ and includes the large semi buried fuel storage tanks, workshops, a pump house, manifold area, electricity sub-station and interceptor. The land is currently leased for grazing sheep and cattle.

Site Sensitivity

The site is assessed as having a Moderately High sensitivity with regard to groundwater as it is underlain by bedrock classified as a Principal Aquifer. This aquifer is however likely to be afforded protection from surface water contamination by low permeability drift deposits. Surface water sensitivity is also classified as Moderately High as an unnamed stream flows along the western boundary of the site via which contamination could be distributed to the wider catchment. The site’s ecological sensitivity is classified as Low.

Potential Sources of Contamination

A number of potential sources of contamination have been identified at the site, all associated with its former use a fuel pumping station / storage facility. These include fuel storage tanks and the associated underground and above ground pipeline infrastructure and pump house, smaller above ground fuel storage tanks, transformer oils, an in-filled pond, an historical burning area (for combustion of hedgerow and grass cuttings), and a ‘lead pit’, historically used for disposing of dredging from the cleaning of the fuel tanks. The potential contaminants of concern include petroleum hydrocarbons, polycyclic aromatic hydrocarbons and tetra-ethyl lead.

Preliminary Risk Assessment

Initially, a number of potentially significant risks from potential sources of contamination were identified based on the use of the site, history and sensitivity. The risks ranged from moderate to negligible depending on the potential source pathway receptor linkage. A targeted intrusive investigation was undertaken in order to refine the preliminary risk assessment.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 1 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

Site Investigation Strategy

The objective of the intrusive investigation was to target areas identified as presenting the greatest risks to land quality, controlled waters and site users identified by the preliminary qualitative risk assessment. In the first instance, it was considered appropriate to investigate all sources of contamination where a moderate risk was assessed. In addition it was also considered appropriate, and cost effective, to investigate other sources at the same time given their similar nature. This will add additional confidence to the site investigation results and help deliver the objectives of the LQA. The works were planned to provide sufficient detail to allow identification of any major contamination concerns on site and the formulation of an outline remedial options assessment, if required, or more detailed investigation where necessary.

Investigation Works Undertaken

An intrusive investigation was undertaken in November 2012. Two ‘rotary open hole’ boreholes were advanced to 11m below ground level and were installed with groundwater monitoring wells, to supplement information obtainable from a number of existing boreholes remaining from a previous investigation. Five window sample holes were also advanced to depths of up to 5m, targeting specific potential sources of contamination. The window sample hole positioned at the location of the in-filled pond was installed with a gas monitoring well. Soil arisings from all positions were logged and samples obtained for chemical analysis of key contaminants. One round of groundwater and surface water monitoring was undertaken in January 2013 and ground gases at the in-filled pond were also measured.

Ground Conditions Identified

Made Ground was encountered in all borehole and window sample locations. Generally, Made Ground consisted of soft to firm clay with low but varying proportions of sand and gravel, to depths of between 1 and 1.2m below ground level. Deeper Made Ground was observed at the in-filled pond (to 3m below ground level) and at the historical lead pit (to 3.1m below ground level), where a fuel odour was present between 1 and 2.9m.

Natural strata of firm to stiff slightly gravelly clay were observed in each of the borehole locations. This is consistent with the review of geological maps in advance of intrusive works, which indicated that the site is underlain by Devensian Till (Diamicton).

Groundwater was discontinuous across the site within the Till. Where water levels allowed it was possible to determine that groundwater flow direction was toward the south west.

Summary of Site Investigation Results

The results of chemical analysis of soil samples do not indicate widespread contamination and contaminant concentrations are generally below generic assessment criteria (GAC) for commercial / industrial sites. The only exception to this was an exceedence of the GAC for lead at a location beneath an overhead fuel storage tank (1100 mg/kg against a GAC of 750 mg/kg). Groundwater and surface water samples did not contain any organic contamination above analytical detection limits and toxic metal concentrations were consistently below environmental quality standards. No ground gases (methane, carbon dioxide or hydrogen sulphide) were detected at the location of the former pond.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 2 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

Updated Risk Assessment

An updated qualitative risk assessment was undertaken at the site based on the findings of both the desk study and the intrusive investigation. On this basis, the updated risk assessment did not identify any risks greater than Negligible, with the exception of the risk to below ground workers from lead which is assessed as Moderate / Low, although this could be easily reduced to Negligible by use of appropriate PPE and risk assessment

It should be noted that the assessment is only based on a relatively small number of sampling locations and one round of gas monitoring, as such there is the possibility that localised areas of contamination remain unidentified or that gas concentrations fluctuate at the site. However, there is a good level of confidence from the information gathered that there is not significant and widespread contamination across the site.

Risk Descriptions

The following table provides definitions for the risk categories used in both the preliminary and updated risk assessments.

Term Description Severe harm to a receptor may already be occurring OR a high likelihood that severe harm will Very High arise to a receptor, unless immediate remedial action works/mitigation measures are Risk undertaken. Harm is likely to arise to a receptor, and is likely to be severe, unless appropriate remedial High Risk actions/mitigation measures are undertaken. Remedial works may be required in the short term, but likely to be required over the long term. Moderate Possible that harm could arise to a receptor but low likelihood that such harm would be severe. Risk Harm is likely to be medium. Some remedial works may be required in the long term. Possible that harm could arise to a receptor, but where a combination of likelihood and Moderate/ consequence results in a risk that is above low, but is not of sufficient concern to be classified Low Risk as medium. It can be driven by cases where there is an acute risk which carries a severe consequence, but where the exposure is unlikely. Low Risk Possible that harm could arise to a receptor. Such harm would at worse normally be mild. Negligible Low likelihood that harm could arise to a receptor. Such harm unlikely to be any worse than Risk mild.

Overall Land Quality and Suitability for Use

Overall, based on the findings of the desk study, intrusive investigation and risk assessments summarised above it is considered unlikely that there will be any land quality issues of concern constraining the use or redevelopment of the site for similar commercial / industrial use.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 3 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

1. Introduction

In August 2012, SKM Enviros (SKM) was commissioned by the Defence Infrastructure Organisation (DIO) to undertake a Phase One Land Quality Assessment (LQA) at the Government Pipelines and Storage System (GPSS) facility at Backford, Cheshire. There are two facilities at Backford, known as ‘North’ and ‘South’ and this report is concerned solely with the southern site, hereafter referred to as GPSS Backford South. This commission was carried out in accordance with the terms and conditions of FATS3, the Framework Agreement for Technical Support under Tasking Order FTS3/ELMG/100.

1.1. Objectives

The objectives of this LQA are to evaluate potential risks to human health and controlled waters which will allow identification of potential environmental risks for the MOD and support the disposal process for the site. The assessment has been completed on the understanding that the site is to be divested for continued or future commercial / industrial use (as a fuel management facility).

This LQA Report sets out the factual information and other evidence gathered through a desk based assessment relating to the environmental condition of the site. The report establishes the overall site condition by identifying potential sources of contamination and receptors which may be sensitive to such contamination and by providing an appraisal of environmental risks. These risks are then further assessed by analysing soil, groundwater and surface water chemical data, obtained through an intrusive ground investigation and monitoring programme.

1.2. Methodology

The assessment involved a review of available background information about the site and its neighbours from both public and Ministry of Defence (MOD) sources, together with a site reconnaissance undertaken on the 20th September 2012.

Information concerning current and past site use has been obtained by interviewing staff on site, from a review of historical site records and historical Ordnance Survey (OS) maps.

Information on the site sensitivity was obtained from geological and hydrogeological maps, together with information held by the Environment Agency and other regulatory authorities. These bodies were not contacted directly but the information was provided by a commercial search company, Landmark Information Group’s Envirocheck® report.

A previous environmental assessment report dated November 2007 (Ref. 1) has also been reviewed and the information used to supplement this LQA.

Data obtained from the public register relating to the site and its neighbours included information on the following:

 Licensed and unlicensed waste disposal facilities (present and past);

 Environmental Permits (formerly Integrated Pollution Prevention and Control Permits) under the Environmental Protection Act 1990;

 Local Authority Environmental Permits (formerly Pollution Control Authorisations) under the Environmental Protection Act 1990;

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 4 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

 Consents or enforcements under the Planning (Hazardous Substances) Act 1990;

 Authorisations under the Radioactive Substances Act 1993;

 Information regarding contaminative uses from the planning register;

 Consents to discharge to controlled waters;

 Consents to discharge trade effluent to the foul sewer;

 Licensed groundwater and surface water abstractions;

 Details of pollution incidents; and

 Breaches or prosecutions under environmental legislation.

Based on the information described above a qualitative risk assessment has been undertaken addressing the significance of any potential contamination identified in relation to current or future use of the site. The risk assessment was used to inform an intrusive investigation targeting those risks assessed as unacceptable or requiring further information to confirm the level of risk. The following works were undertaken on site between 20th and 21st December 2012:

 Drilling of two boreholes using a rotary drilling rig and five window sample boreholes using a Terrier rig to facilitate visual and olfactory observations of sub-surface conditions and collection of soil samples;

 Completion of the two rotary boreholes as groundwater monitoring points to facilitate the collection of groundwater data and samples. One of the window sample holes was also installed with a ground gas monitoring well;

 One round of groundwater sampling and gas monitoring from the newly installed monitoring wells and wells that remain on site from an earlier site investigation; and

 Sampling of the surface watercourse which bounds the west of the site, from positions immediately upstream and downstream of the site.

Based on the works described above and on the data following laboratory analysis of soil and groundwater samples a Tier 1 generic risk assessment and update of the conceptual site model has been undertaken to assess the significance of any potential contamination identified in relation to the current or future commercial / industrial use of the site (as a fuel management facility).

1.3. Framework for Contaminated Land Assessment

Contaminated land risk assessment is based on development of a conceptual model for the site. This model is a representation of the relationship between contaminant sources, pathways and receptors developed on the basis of hazard identification. Risk assessment is the process of collating known information on a hazard or set of hazards in order to estimate actual or potential risks to receptors. The guiding principle behind this approach is an attempt to establish connecting links between a hazardous source, via an exposure pathway to a potential receptor, referred to as a ‘pollutant linkage’. If there is no pollutant linkage, then there is no risk. Therefore, only where a viable pollutant linkage is established does this assessment go on to consider the level of risk.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 5 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

This approach is in accordance with the Department for the Environment Food and Rural Affairs (DEFRA) Statutory Guidance on Contaminated Land (Ref. 2) and the DEFRA / Environment Agency (EA) Model Procedures (CLR11, Ref. 3). The risk assessment undertaken in this document comprises a ‘preliminary risk assessment’ in the terminology used in CLR11.

1.4. Structure of this Report

This report is structured as follows:

 Chapter 2: Provides a description of the site layout and an outline of the activities undertaken and current potential sources of contamination;

 Chapter 3: Outlines site history including a review of historical maps, and a review of previous land quality assessments;

 Chapter 4: Provides the environmental site setting and sensitivity in relation to its geology, hydrogeology, hydrology and ecology;

 Chapter 5: Outlines the initial conceptual site model and qualitative risk assessment and provides justification for the areas prioritised for this phase of intrusive assessment;

 Chapter 6: Provides an outline of the site investigation strategy;

 Chapter 7: Details the site investigation methodology;

 Chapter 8: Summarises the observed ground conditions;

 Chapter 9: Summarises the methodology for interpreting the chemical analysis results;

 Chapter 10: Details the assessment of the chemical analysis results;

 Chapter 11: Reviews the conceptual site model and presents an updated qualitative risk assessment;

 Chapter 12: Presents a summary of the overall land quality and suitability of the site for its current and future use; and

 Chapter 13: Details the references.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 6 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

2. Site Description

2.1. Site Location

GPSS Backford South is centred on National Grid Reference (NGR) 340740, 371520, west of the village of Backford, approximately 6 km north of Chester town centre. The location of the site is shown on Figure 1.

2.2. Site Layout

The site occupies an area of 7 hectares (Ha). The site is generally flat with the western half of the site sloping gently down to the south. Seven large mounds cover much of this area (beneath which are fuel storage tanks) and a grassed earth bund is present along parts of the western and southern boundaries. The site is now used for grazing livestock, however it was previously a pumping station and fuel storage facility and the old infrastructure is still present. In the south west corner a pumping house is buried beneath another earth mound and an associated switch room, manifold pit and (empty) diesel tank are also present. The site’s interceptor is also in this south western corner. An electrical substation is present further west on the southern boundary and directly north of this is a small complex of workshops and an office. A steel gantry is situated across the access road to the office buildings, on top of which a tank, thought to have once contained fuel, is present.

A plan of the current site layout is shown in Figure 2. A selection of site photographs is provided in Appendix A.

2.3. Site Operations and Site Use

Historically the site was a pumping station and oil / fuel storage facility, receiving and distributing fuel on the UK OPA fuel pipeline within the Stanlow, Backford North, Worthing and Backford South network. Fuel (primarily A1 Jet Fuel but also diesel, petrol and oil) was stored in seven part-buried tanks which were protected by earth and grass caps. The site is currently maintained by Costain, who visit the site for approximately 4 hours every two weeks.

2.3.1. Petroleum, Oil and Lubricant (POL) Storage

The seven main fuel storage tanks on site have all been emptied, cleaned and filled with water (date unknown). Previously they were used to store aviation fuel, diesel, petrol and oil (at various times). The volume of the tanks is 5500m3 each and they are thought to be of single skin steel construction with concrete covers. They are not internally bunded (although there is one main site bund to the south / west of the site). No incidents have been recorded in relation to leaks from the tanks.

There is an empty above ground diesel storage tank in the south west corner of the site, of approximately 4.5m3 capacity. The tank is unbunded and is thought to be of single skin steel construction. No evidence of spills or leaks was noted to the ground in the vicinity of the tank. A second above ground storage tank is situated on the gantry over the site’s access road, however, its historical use and contents are unknown. A road filling valve is situated at close to ground level and minor staining to hardstanding was noted.

Within the workshop closest to the site entrance approximately forty 5L glass bottles of aviation fuel are present. Some of these are broken and there is staining to the concrete floor. In addition, approximately 50 tubes of lubricating grease are stored in the engineering workshop, however access to this building was not possible during the site walkover.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 7 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

2.3.2. Hazardous and Waste Material Storage

Historically, lead residue from within the tanks was periodically removed, and deposited within a ‘lead pit’, positioned adjacent to the fuel storage tank in the north west of the site, as shown on Figure 2. At the time of the site walkover the pit was identifiable as a grassed mound less than 0.5m high, surrounded by a post and wire fence in poor repair.

A number of fuel / oil drums containing unknown liquids are stored within the northern workshop. Also in this workshop are two 20kg drums of Shell Herder (a compound used for containing oil spills).

A full oil drum is stored in the electrical substation on the southern boundary.

No wastes are currently generated on site.

2.3.3. Asbestos

It is beyond the scope of this LQA to assess or provide an inventory of asbestos containing materials (ACMs) in the fabric of any current or former structures on the site. Nevertheless, the Costain site representative had knowledge of the presence of asbestos as follows:

 Crysotile gaskets in the (sealed) engineering workshop;

 Crysotile tiles in the office floor;

 Within the switch room and possibly in the substation;

 Concrete asbestos from downspouts on the fire pump house and office building, removed, bagged and stored in the engineering workshop; and

 Corrugated roofing sheets in the fire pump house and manifold pit.

An asbestos register is held centrally.

2.3.4. Storage / Use of Explosives and Munitions

Explosive Ordnance is not used or stored at the site and the Costain representative had no knowledge of the site ever having been used for such purposes.

2.3.5. Burning Grounds and Incinerators

The helicopter landing pad in the centre of the site was previously used to burn hedgerow cuttings and other woody waste generated as a result of site maintenance. This practise was stopped two years ago and the resulting ash has been trodden into the surrounding soil by livestock.

2.3.6. Radiological Materials

No radiological materials are used or stored at the site and the Costain site representative was unaware of any historical usage in this respect.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 8 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

2.3.7. Vehicle Washing

No vehicle wash down areas were identified during the site walkover.

2.3.8. Transformers

The transformer building on the southern boundary was inspected during the site walkover and no oil staining to the concrete floor was observed. The date of transformer installation is unknown but given the age of the site, it is possible that the substation apparatus may have contained polychlorinated biphenyls (PCBs). It was not known by the site representative whether the apparatus still contained PCBs and if so in what concentration.

An underground cable connects this transformer to the switch room in the south west corner. The switch room was sealed shut during the site visit and therefore not inspected. Again there is a potential for PCBs to be present.

2.3.9. Site Drainage

Surface and (presumably) shallow groundwater drains from the tank areas in a south / south westerly direction into a drainage pond, situated at the base of the site bund (see Figure 2). From the pond, the water discharges via a sluice valve into a culvert beneath the bund and into an oil – water interceptor on the southern boundary. The interceptor in turn discharges off-site to the south. The interceptor is checked and cleaned periodically and in the eight years experience of the Costain site representative no oils have been detected.

2.3.9.1. Discharge Consents

No discharge consents are in force for the site.

2.3.10. Other Information from the Site Visit

Six boreholes are present in the south west of the site. The condition or depth of the wells were not established however the head works appeared to be in good condition.

2.4. Surrounding Area

The land surrounding the site is used for agriculture (grazing and arable). The southern boundary of the Backford North site is situated within 25m of the north eastern corner of the site under study, the two installations being separated by Chorlton Lane. The fuel storage tanks of Backford North are approximately 125m north east of the site.

2.5. Public Register Information

The Envirocheck report, which contains public register information supplied by the Environment Agency and other statutory authorities, was purchased in August 2012. Key information relating to the site is identified and summarised below with a copy of the full report included in Appendix B.

2.5.1. Industrial Data Entries

The closest contemporary trade directory entry is for an agricultural engineering company, approximately 200m north. There are no other entries within 500m of the site.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 9 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

2.5.2. Fuel Station Entries

There are no fuel station entries identified within 1 km of the site.

2.5.3. Radon

The site is not in a Radon Affected Area (which is defined as an area where less than 1% of homes are above the action level for radon).

2.5.4. Environment Agency Recorded Pollution Incidents

There are three pollution incidents recorded by Envirocheck within 500m of the site. The closest is a Category 2 Significant incident that occurred in 1995 approximately 230m from site, involving the run-off of cattle slurry into an undisclosed water body. The other two records were minor incidents over 400m from site.

2.5.5. Contaminated Land Entries

There are no areas within 1 km of the site that have been determined as Contaminated Land under Section 78R of the Environmental Protection Act 1990.

2.5.6. Other Information

A Hazardous Substance Consent is in force for the Backford North site, 25m to the north east, registered to the Oil Pipelines Agency for a ‘combination of dangerous substances’. The Backford North site is also registered as a COMAH (Control of Major Accident Hazards) site.

No records of other activities that may affect the site were identified within 500m.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 10 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

3. Site History

The site history has been determined from a review of Ordnance Survey (OS) historical maps contained within the Envirocheck® report, and from information provided by site personnel during the site visit. The information below describes the significant historical activities on the site and surrounding area. The historical maps are presented in Appendix C.

3.1. Historical OS Maps

It should be noted that sites with a military or defence connection were often not included on OS maps during the war years and subsequent cold war, for reasons of national security.

3.1.1. On Site

The earliest map dated 1875 shows the site to be farmland, with a pond east of centre. No changes are notable on subsequent maps until 1960, by which time the site has been developed as a fuel storage depot, with the buildings and tank mounds present today being shown. 1993 mapping shows that the site bund to the south and west and a helipad have been constructed. The on-site pond has also been in-filled. No further changes are shown on subsequent mapping up to the present day.

3.1.2. Off Site

The 1875 map shows a number of ponds situated within 10 and 80m of the site (various directions). Chorlton Hall and associated buildings is situated 60m north and Collinge Farm is situated 150m south west. Very little change takes place in the surrounding area to the present day, other than that by 1960 mounds housing tanks are shown on the Backford North site, the closest of which is 120m north west.

3.2. MOD and Other Sources

The GPSS was established to provide a secure oil distribution network for the United Kingdom at the beginning of World War Two in 1939. Over a period of years the pipeline route has been extended and amended, certain sections renewed and re-laid or diverted until it now covers approximately 2,500km of pipe and associated storage depots, pumping stations and other sites (Ref. 4).

In March 2012, Costain was awarded the asset support contract for the operation and maintenance of the GPSS on behalf of the OPA.

In November 2007 an Environmental Site Assessment report was issued by Environ UK Ltd to the Oil and Pipelines Agency, which covered the Backford North and Backford South sites (Ref. 1). The report makes the following observations in respect of Backford South:

 The site was constructed in 1939-40 and is not shown until 1960 mapping due the militarily sensitive nature of the site.

 Backford South was operational until the early 1990s. As part of the decommissioning process the tanks – which are reported to be 5500m3 capacity, of steel construction encased in concrete – were ‘water-bottomed’ and all pipes were also filled with water.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 11 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

 A number of boreholes and window sample holes were drilled as part of the assessment. Hydrocarbon contamination was observed at a number of locations (soil and groundwater) however contamination was not generally significant or widespread. No fuel hydrocarbons were detected in groundwater within the underlying sandstone aquifer, with the exception that MTBE concentrations at two locations were moderately high in relation to odour and taste thresholds (MTBE being an additive within leaded petrol). Two gas monitoring rounds were undertaken from each of the boreholes and Environ concluded that the site was not affected by significant levels of land gas, although slightly elevated concentrations of methane (3.1% by volume) were recorded on one occasion at one location. Carbon dioxide levels were generally below 1.5%, although maximum concentrations of 7.8% and 4.5% were observed at one location. Gas flows were generally low (maximum of 0.7 l/hr) or negative.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 12 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

4. Site Sensitivity

4.1. Geology

4.1.1. Made Ground

The geological map for the area does not identify any Made Ground either on site, or in the vicinity of the site.

4.1.2. Drift

The geological map for the area indicates that superficial deposits comprising Devensian Till (Diamicton) underlie the entire site. A borehole drilled in 1934 located approximately 300m north of the site records the Till to be approximately 5m thick (Ref. 5)

4.1.3. Solid

The geological map for the area indicates that all areas of the site are underlain by the Chester Pebble Beds, which is a gravelly sandstone formation.

4.2. Hydrogeology

The Environment Agency (EA) website (Ref. 6) records the superficial deposits (Diamicton) as Unproductive Strata (deposits with low permeability which have negligible significance for water supply or river base flow).

The sandstone bedrock is recorded as a Principal Aquifer, comprising strata that have high intergranular and/or fracture permeability, providing a high level of water storage. The sandstone may support water supply and / or river base flow on a strategic scale (Ref. 6).

The EA website (Ref. 6) does not list the site area as being a designated groundwater source protection zone.

The Envirocheck report identifies one current licenced groundwater abstraction within 1km of the site, at Chorlton Lodge Farm 350m north. The abstraction is for general agricultural purposes. The closest abstraction for potable use is at a domestic property, 1.25km north east.

4.3. Hydrology

The nearest surface water feature is a drain adjacent to the western boundary. The drain flows southwards towards the Shropshire Union Canal which is situated 470m south of the site. Backford Brook, which also flows southwards into the Canal is situated 820m west.

There are a number of small ponds located within 125m south and west of the site, the closest of which lies 10m south.

Historically the Environment Agency General Quality Assessment (GQA) Scheme assessed surface waters in England and Wales according to their chemical and biological quality. Envirocheck record that the nearest monitoring point was on the Shropshire Union Canal, 470m south of the site and the most recent grade classified in 2000 was C (Fairly Good). Under the Agency’s current River Basin Management Plan, the Canal is also the closest monitoring point to the site and it is currently assessed as having a ‘moderate’ ecological status.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 13 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

The closest surface water abstraction licence is for a point on the canal approximately 700m east of the site. The licence is under the name of British Waterways and relates to industrial usage at the Backford North fuel facility.

There is one current discharge consent in operation within 500m of the site, which relates to the discharge of treated sewage from Chorlton Lodge Farm into the Shropshire Union Canal.

4.4. Ecology

The site lies within an area of adopted greenbelt, but otherwise there are no ecologically sensitive designations attributed to the site or its immediate surroundings.

4.5. Site Sensitivity

Groundwater sensitivity: Moderately High The site is assessed as having a Moderately High sensitivity with regard to groundwater. Whilst the solid geology is classified as a Principal Aquifer, this is likely to be afforded protection from surface contamination by low permeability superficial deposits. The site does not lie within a groundwater Source Protection Zone and the closest licenced potable abstraction is over 1km from the site.

Surface Water Sensitivity: Moderately High The site is assessed as having a Moderately High sensitivity with regard to surface water. An unnamed stream is situated adjacent to the Western boundary, via which contamination from the site could be distributed to the wider catchment and in particular to the Shropshire Union Canal, 470m south. There are also a number of small ponds within close proximity to the site.

Ecological Sensitivity: Low Ecological sensitivity has been assessed as Low as the site does not lie within an area designated as ecologically vulnerable.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 14 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

5. Initial Conceptual Site Model and Environmental Risk Assessment

This chapter presents the initial conceptual site model (CSM) developed for the site and identifies the presence of any potentially unacceptable risks. The conceptual model is a representation of the relationship between contaminant sources, pathways and receptors developed on the basis of hazard identification. Unique identification numbers or letters are allocated to each source, pathway and receptor, these are then carried forward to the CSM (as shown on Figure 3) and the risk assessment.

5.1. Conceptual Model Outline

The following provides a brief summary of the key features of the site (as detailed in full in Chapters 2 to 4) of relevance to the risk assessment. This conceptual model is shown schematically in Figure 3 along with the contaminant sources detailed below.

Although currently leased for grazing, the site was formerly used as a fuel pumping station and fuel storage depot. The infrastructure for this previous use is still in place and includes part-buried fuel storage tanks, a pump house / manifold area, an electricity substation as well as workshops and office / ancillary buildings. An historical ‘lead pit’ (used for disposing of residues cleaned out of the fuel storage tanks) is present in the north west of the site. It is thought that the site was last used as a pumping station / storage depot in the early 1990s and Costain staff report that the fuel storage tanks were emptied, cleaned and filled with water at the time of decommissioning.

The site is underlain by superficial deposits of Till (Diamicton) and the underlying bedrock is sandstone of the Cheshire Pebble Beds Formation. These strata are classified as Unproductive Strata and a Principal Aquifer respectively. The site does not lie within a groundwater protection zone, although a licence to abstract groundwater for agricultural purposes is in operation 350m to the north.

Although the site is generally level, beyond the southern boundary the topography slopes gently down to the south / south east. An earth bund on the western and southern boundaries causes water from the western areas of the site (storage tank area) to collect on the northern side of this bund, indicating that surface water and shallow groundwater flow in a south / south easterly direction. Ponded water is discharged via a sluice valve to an oil-water interceptor on the southern side of the bund, from where water leaves the site to the south joining the nearest surface water which is an unnamed drain that runs adjacent to the site’s western boundary.

The future end use for which the assessment has been undertaken is continued commercial / industrial use.

5.2. Potential Contaminant Sources

A number of potential sources of contamination have been identified at the site, generally deriving from the site’s historical use a fuel storage facility and pumping station.

5.2.1. On Site

The potential on site sources of contamination include:

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 15 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

Potential Source (associated Associated feature contaminants given in brackets) assessment) Potential Source Potential Source Number (numbers on Figures 2 and 3) Location Area (shown carried through to risk

Decommissioned semi S1 buried fuel storage tanks 7 No 5500m3 part-buried tanks. Ref. 1 (hydrocarbons) Decommissioned pump Pump house (sealed, not inspected) Ref. 2.1 house and associated S2 Manifold pit Ref. 2.2 pipe network (hydrocarbons) High pressure below ground pipeline Ref. 2.3 Decommissioned above Empty diesel tank close to pump room Ref. 3.1 S3 ground fuel / oil storage Empty (presumed) tank above gantry, whose historical contents Ref. 3.2 tanks (hydrocarbons) are unknown, assumed to be fuel Electrical equipment Electrical substation on southern boundary Ref. 4.1 S4 (PCBs) Switch room associated with pump house Ref. 4.2 Historical burning area Soils surrounding the Helipad where ash from vegetation burning S5 Ref. 5 (hydrocarbons, PAH) has been trodden in by cattle In-filled pond (ground Historical pond, east of centre. Materials used to infill the pond S6 Ref. 6 gases) unknown. Lead pit (hydrocarbons, In-filled pit, now covered by grass and other vegetation, adjacent S7 Ref. 7 tetra-ethyl-lead) to fuel storage tank in north west of site.

5.2.2. Off Site

The only potential sources of contamination identified off-site are the fuel storage tanks to the north west (Backford North fuel storage facility). The closest part-underground storage tank is situated 120m north west and, given the distance from site and the fact that the area between is underlain by low permeability drift deposits, the likelihood of any leaks from Backford North impacting the site is considered to be low. Therefore, this potential source is not carried forward to the risk assessment stage below, but should be noted in the event that hydrocarbon contamination is identified in groundwater on the north western boundary of the site. 5.3. Identified Pathways

Potential environmental fate and exposure pathways specific to the site are:

 Direct contact, ingestion or inhalation (pathway P1);

 Leaching of contamination from soils via rainwater infiltration (pathway P2);

 Vertical and lateral migration in groundwater (pathway P3);

 Surface runoff into adjacent surface water via site drainage system or direct run-off (pathway P4);

 Direct contact (buildings and services) (pathway P5); and

 Vapour migration and accumulation of vapours (pathway P6).

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 16 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

5.4. Identified Receptors

Potential receptors specific to the site are:

Human health Current and future site users under commercial industrial use (receptor A).

Human health Personnel involved in below ground or maintenance works (receptor B).

Groundwater Chester Pebble Beds, Principal Aquifer (receptor C).

Surface water Drain adjacent to site, with potential to distribute contaminants to the wider catchment (receptor D).

Buildings and Services As a result of chemical attack or vapour ignition / explosion (receptor E).

5.5. Preliminary Risk Assessment

A preliminary risk assessment has been undertaken for these potential source-pathway-receptor linkages to identify potentially unacceptable risks on a qualitative basis. This approach is based on DEFRA (Ref. 7) and Construction Industry Research and Information Association (CIRIA) guidance (Ref. 8) on risk assessment and Model Procedures, whilst reference has also been given to the DIO LQA Management Guide (Ref. 9). Risk is therefore based on a consideration of both:

 the likelihood of an event (probability – takes into account both the presence of the hazard and receptor and the integrity of the pathway); and

 the severity of the potential consequence (takes into account both the potential severity of the hazard and the sensitivity of the receptor).

Further information on the risk assessment methodology used is given in Appendix D. The method of dealing with identified risks and the level of significance of those risks will be a function of site use. Potentially unacceptable risks identified for current and continued commercial / industrial use of the site are considered in Table 5.1 and summarised in Table 5.2.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 17 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

Table 5.1: Potential environmental risks for current / future commercial / industrial use and during below ground maintenance works Potential Associated Potential Potential Potential Likelihood of Risk / Pathways to Hazard Source Pollutant Receptors Occurrence Significance Receptors [severity] S1 Hydrocarbons Humans Health Hazard The tanks were emptied Decommissioned (aviation fuel) and decommissioned in semi buried fuel the 1990s. No evidence storage tanks of contamination was observable on the ground surface A. Current / P1. Direct Medium Unlikely Low future use contact, Disturbance of the ground ingestion, is unlikely during current inhalation operations. B. Below ground P1 – Direct Mild Low Likelihood Low maintenance contact, Disturbance of the ground (Could be workers ingestion, is likely, but any exposure reduced to inhalation during ground works will Negligible by be very short term (acute utilising rather than chronic). appropriate PPE / risk assessment) Controlled Waters Environmental Tanks currently impact decommissioned and water filled. No records of any previous pollution incidents. Site is underlain by low permeability drift which will minimise sub-surface migration of contaminants. However, historical tank integrity unknown and large volumes were stored. C. Groundwater P2 and P3. Impact on Low likelihood Moderate Principal Aquifer Leaching of groundwater Aquifer is likely to be contamination quality afforded protection by low from soils by Severe permeability drift rainwater [severe deposits. infiltration and classification migration primarily due to through the potentially groundwater large volumes of contaminant] D. Surface water P3. Vertical and Impact on Low likelihood Moderate Drain on western lateral migration surface water Lateral migration of boundary in groundwater Severe contaminants unlikely due to low permeability drift deposits. No evidence of contamination on ground surface. P4. Surface Impact on Unlikely Low water runoff surface water No evidence of Medium contamination on ground surface and site drainage passes through an interceptor. The tanks are semi buried

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 18 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

Potential Associated Potential Potential Potential Likelihood of Risk / Pathways to Hazard Source Pollutant Receptors Occurrence Significance Receptors [severity] S1 Hydrocarbons E. Buildings and P5. Direct Damage to Unlikely Negligible Decommissioned (aviation fuel) services contact buildings and Site mothballed in 1990s. semi buried fuel continued services Buildings and services storage tanks Mild have been present many continued years and no impacts to date. P6. Vapour Damage to Low Likelihood Moderate accumulation services and No evidence or records of structures spills or leaks and Severe buildings and services have been present many years with no recorded impacts to date. Presence of potentially significant volumes of contamination within subsurface is possible given the size of the infrastructure and the integrity of redundant underground tanks not established. S2. Hydrocarbons Humans Health Hazard The site was Decommissioned (aviation fuel) decommissioned in the pump house and 1990s. No evidence or associated pipe records of leaks or spills. network A. Current / P1. Direct Medium Unlikely Low future use contact, Disturbance of the ground ingestion, is unlikely during current inhalation operations. B. Below ground P1 – Direct Mild Low Likelihood Low maintenance contact, Disturbance of the ground (Could be workers ingestion, is likely, but any exposure reduced to inhalation during ground works will Negligible by be very short term (acute utilising rather than chronic). appropriate PPE / risk assessment) Controlled Waters Environmental No records of any impact previous pollution incidents. Site is underlain by low permeability drift which will minimise sub-surface migration of contaminants. However, historical tank integrity unknown and large volumes were transferred.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 19 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

Potential Associated Potential Potential Potential Likelihood of Risk / Pathways to Hazard Source Pollutant Receptors Occurrence Significance Receptors [severity] S2. Hydrocarbons C. Groundwater P2 and P3. Impact on Low likelihood Moderate / Decommissioned (aviation fuel) Principal Aquifer Leaching of groundwater If historical contamination Low pump house and continued contamination quality has occurred, aquifer is associated pipe from soils by Medium likely to be afforded network rainwater protection by low continued infiltration and permeability drift migration deposits. through groundwater D. Surface water P3. Vertical and Impact on Low likelihood Moderate / Drain on western lateral migration surface water Lateral migration of Low boundary in groundwater Medium contaminants unlikely due to low permeability drift deposits. No evidence of contamination on ground surface. P4. Surface Impact on Low likelihood Moderate / water runoff surface water No contamination Low Medium observed on site surface but potential exists for historical contamination to be mobilised from surface soils during heavy rain. E. Buildings and P5. Direct Damage to Unlikely Negligible services contact buildings and Site mothballed in 1990s. services Buildings and services Mild have been present many years and no impacts to date. P6. Vapour Damage to Unlikely. Moderate / accumulation services and No evidence or records of Low structures spills or leaks and Severe buildings and services have been present many years with no recorded impacts to date.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 20 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

Potential Associated Potential Potential Potential Likelihood of Risk / Pathways to Hazard Source Pollutant Receptors Occurrence Significance Receptors [severity] S3. Hydrocarbons Humans Health Hazard Diesel tank is empty and Decommissioned no staining or spills were above ground noted to ground surface. fuel / oil storage Historically however spills tanks may have permeated the surrounding soils. Minor staining noted to hardstanding close to gantry tank. A. Current / P1. Direct Medium Unlikely Low future use contact, Disturbance of the ground ingestion, is unlikely during current inhalation operations. B. Below ground P1 – Direct Mild Low Likelihood Low maintenance contact, Disturbance of the ground (Could be workers ingestion, is likely, but any exposure reduced to inhalation during ground works will Negligible by be very short term (acute utilising rather than chronic). appropriate PPE / risk assessment) Controlled Waters Environmental Diesel tank is empty and impact no staining or spills were noted to ground surface. Historically however spills may have permeated the surrounding soils. Minor staining noted to hardstanding close to gantry tank. C. Groundwater P2 and P3. Impact on Low likelihood Moderate / Principal Aquifer Leaching of groundwater If historical contamination Low contamination quality has occurred, aquifer is from soils by Medium likely to be afforded rainwater protection by low infiltration and permeability drift migration deposits. through groundwater

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 21 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

Potential Associated Potential Potential Potential Likelihood of Risk / Pathways to Hazard Source Pollutant Receptors Occurrence Significance Receptors [severity] S3. Hydrocarbons D. Surface water P2 and P3. Impact on Low likelihood Moderate / Decommissioned continued Drain on western Leaching of groundwater Lateral migration of Low above ground boundary contamination quality contaminants unlikely due fuel / oil storage from soils by Medium to low permeability drift tanks continued rainwater deposits. infiltration and migration through groundwater P4. Surface Impact on Unlikely Low water runoff surface water Surface run-off from the Medium diesel tank would be prevented from reaching the stream by the site bund. The gantry tank is too far away from the stream for surface run-off to be a viable pathway. E. Buildings and P5. Direct Damage to Unlikely Negligible services contact buildings and Historical spills or leaks services from these vessels are Mild unlikely to be of significant magnitude to present a risk to buildings / services. P6. Vapour Damage to Unlikely Moderate / accumulation services and Buildings and services Low structures have been present many Severe years with no recorded impacts to date. Presence of significant volumes of contamination within subsurface from this source is not likely given the size of the above ground infrastructure.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 22 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

Potential Associated Potential Potential Potential Likelihood of Risk / Pathways to Hazard Source Pollutant Receptors Occurrence Significance Receptors [severity] S4. Electrical PCBs Humans Health Hazard It is possible that the Equipment substation apparatus may have contained PCBs. However, it was not known whether the apparatus still contained PCBs and if so at what concentration. However, the transformers are of a small size, therefore only small volumes of oil may have leaked. Any impacted ground likely to be very localised. A. Current / P1. Direct Medium Unlikely Low future use contact, Disturbance of the ground ingestion, in the vicinity of the inhalation transformer is unlikely during normal operations. B. Below ground P1 - Direct Medium Low Likelihood Moderate / maintenance contact, Disturbance of the ground Low workers ingestion, is likely, but any exposure (Could be inhalation during groundworks will reduced by be very short term (acute utilising rather than chronic). appropriate PPE / risk assessment) Controlled Waters Environmental It is possible that the impact substation apparatus may have contained PCBs. However, it was not known whether the apparatus still contained PCBs and if so at what concentration. However, the transformers are of a small size, therefore only small volumes of oil may have leaked. Any impacted ground likely to be very localised. C. Groundwater P2 and P3. Impact on Unlikely Low Leaching of groundwater Principal Aquifer PCBs are highly immobile contamination quality in the environment and from soils by Medium unlikely to migrate far rainwater from the source of infiltration and deposition. The aquifer is migration likely to be afforded through protection by low groundwater permeability drift deposits.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 23 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

Potential Associated Potential Potential Potential Likelihood of Risk / Pathways to Hazard Source Pollutant Receptors Occurrence Significance Receptors [severity] S4. Electrical PCBs D. Surface water P2 and P3. Impact on Unlikely. Low Equipment continued Drain on western Leaching of surface water Any leaks are likely to be continued boundary contamination Medium contained by from soils by hardstanding. If oil does rainwater reach sub-surface, low infiltration and permeability drift and low migration solubility of PCBs will limit through migration. groundwater P4. Surface Impact on Unlikely Low water runoff surface water PCBs are highly immobile quality in the environment and Medium unlikely to migrate far from the source of deposition. It is considered very unlikely that appreciable quantities of PCBs (if present) would reach the surface water by overland flow or runoff. S5. Historical Hydrocarbons, Humans Health Hazard Historical burning and burning area PAH incorporation into surrounding soils by cattle means that contaminants may be present within soils. A. Current / P1. Direct Medium Unlikely Low future use contact, Disturbance of the ground ingestion, in the vicinity of the inhalation transformer is unlikely during normal operations. B. Below ground P1 - Direct Medium Low Likelihood Moderate / maintenance contact, Disturbance of the ground Low workers ingestion, is likely, but any exposure (Could be inhalation during groundworks will reduced by be very short term (acute utilising rather than chronic). appropriate PPE / risk assessment) Controlled Waters Environmental Historical burning and impact incorporation into surrounding soils by cattle means that contaminants may be present within soils, although their extent will be limited. C. Groundwater P2 and P3. Impact on Unlikely. Low Principal Aquifer Leaching of groundwater Aquifer will be afforded contamination Medium protection by low from soils by permeability drift. rainwater infiltration and migration through groundwater

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 24 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

Potential Associated Potential Potential Potential Likelihood of Risk / Pathways to Hazard Source Pollutant Receptors Occurrence Significance Receptors [severity] S5. Historical Hydrocarbons, D. Surface water P2 and P3. Impact on Unlikely. Low burning area PAH Drain on western Leaching of surface water Low permeability drift will continued continued boundary contamination Medium limit likelihood of from soils by migration. rainwater infiltration and migration through groundwater P4. Direct run- Impact on Low likelihood. Moderate / off surface water Distance to water course Low Medium makes significant pollution unlikely, however it is possible hydrocarbons sorbed to soil particles may be washed into drain or pond to north of site bund. S6. In-filled pond Ground gases Humans Health Hazard Pond in-filled sometime (methane, between 1979 and 1993. carbon There are no buildings at dioxide) this location and low permeability drift likely to limit gas migration, if present. Area is limited in extent. A. Current / P1. Inhalation Severe Unlikely Moderate / future use The site is not currently Low staffed full time. Gas unlikely to migrate to buildings as above, with preferential pathway being to atmosphere B. Below ground P1. Inhalation Severe Low likelihood Moderate maintenance There is an increased (Could be workers likelihood of exposure in reduced to any below ground Negligible by excavations in the area. utilising Gas unlikely to migrate appropriate due to geology with PPE / risk preferential pathway assessment) being to atmosphere . E. Buildings and P6. vapour Damage to Unlikely. Moderate / services accumulation services No reported issued of gas Low Severe accumulation and no previous damage to buildings. Any gas present likely to escape to atmosphere.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 25 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

Potential Associated Potential Potential Potential Likelihood of Risk / Pathways to Hazard Source Pollutant Receptors Occurrence Significance Receptors [severity] S7. Historical Hydrocarbons, Humans Health Hazard Impact on soils from Lead Pit tetra-ethyl- waste deposition likely to lead (tank be relatively localised so residues) exposure will only occur if intrusive works are needed in this area A. Current / P1. Direct Medium Unlikely Low future use contact, Disturbance of the ground ingestion, in the vicinity of the burial inhalation pit is unlikely during normal operations. B. Below ground P1 - Direct Medium Low Likelihood Moderate / maintenance contact, Disturbance of the ground Low workers ingestion, is likely, but any exposure (Could be inhalation during groundworks will reduced by be very short term (acute utilising rather than chronic). appropriate PPE / risk assessment) Controlled Waters Environmental Low permeability soils are impact likely to limit migration of contaminants, protecting surface waters and the underlying aquifer. C. Groundwater P2 and P3. Impact on Low Likelihood. Moderate / Principal Aquifer Leaching of groundwater Aquifer will be afforded Low contamination Medium protection by low from soils by permeability drift. rainwater infiltration and migration through groundwater D. Surface water P3. Migration Impact on Unlikely. Low Drain on western through surface water Low permeability drift will boundary groundwater Medium limit likelihood of base flow migration. E. Buildings and P5. Direct Damage to Unlikely Low services contact or services There are no buildings in P6.vapour Medium the vicinity of the lead pit accumulation and vapour migration will be restricted by geological conditions..

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 26 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

5.6. Summary of Environmental Risks

Table 5.2 below summarises the risks from the identified sources.

Table 5.2: Summary of Risks Potential Contaminant Source

Usage Scenario / Receptor gases) (PCBs) network ethyl-lead) storage tanks (hydrocarbons) (hydrocarbons) associated pipe pump house and Decommissioned Decommissioned (hydrocarbons) Historical Lead Pit Electrical equipment (hydrocarbons, PAH) (hydrocarbons, tetra- In-filled pond (ground above ground fuel / oil Historical burning area uried fuel storage tanks Decommissioned semi b CSM CSM CSM CSM CSM CSM CSM Source S1 Source S2 Source S3 Source S4 Source S5 Source S6 Source S7 Human health: Current and Moderate / Low Low Low Low Low Low future commercial / industrial use Low Human health: During below Moderate / Moderate / Moderate / Low Low Low Moderate ground maintenance works* Low Low Low Groundwater Moderate / Moderate / Moderate / Moderate Low Low - Low Low Low Surface water (via baseflow) Moderate / Moderate / Moderate Low Low - Low Low Low Surface water (via runoff) Moderate / Moderate / Low Low Low - - Low Low Buildings and services (direct Negligible Negligible Negligible - - - Low contact) Buildings and services (vapour Moderate / Moderate / Moderate / Moderate - - Low accumulation) Low Low Low *Risk can be reduced by utilising appropriate risk assessment and personal protective equipment (PPE)

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 27 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

6. Site Investigation Strategy

6.1. Scope of Works

The objective of the intrusive investigation was to target areas identified as presenting the greatest risks to land quality, controlled waters and site users identified by the preliminary qualitative risk assessment. In the first instance, it was been considered appropriate to investigate all sources of contamination where a moderate risk was assessed. In addition it was also considered appropriate, and cost effective, to investigate other sources at the same time given their similar nature. This will add additional confidence to the site investigation results and help deliver the objectives of the LQA. These areas are summarised in Table 6.1.

Table 6.1: Selected Investigation Targets Highest Risks Contaminants Source Ref. Description Identified* of Concern

S1. Moderate risks to Decommissione groundwater, 3 Hydrocarbons, d semi buried 1 surface water and Seven part-buried tanks, volume >5000m including poly- fuel storage buildings and aromatic tanks services hydrocarbons S2 2.1 Moderate / Low risk Pump house from aviation Decommissione to controlled waters fuel and other d pump house 2.2 Manifold pit fuels / oils and associated and to buildings pipe network 2.3 and services High pressure below ground pipeline

S3 3.1 Moderate / Low risk Empty diesel tank close to pump room Decommissione 3.2 to controlled waters d above ground Empty (presumed) tank above gantry, whose historical fuel / oil storage and to buildings contents are unknown, assumed to be fuel tanks and services

S5 Historical 5 Moderate / Low risk Soils surrounding the Helipad where ash from vegetation burning area to surface water burning has been trodden in by cattle 6 Moderate risk to current site users Historical pond, east of centre. Materials used to infill S6 In-filled pond Ground gases and to buildings the pond unknown and services 7 Moderate / Low S7. Historical Hydrocarbons, risks to Historical pit used to dispose of tank residues lead pit tetra-ethyl-lead. groundwater. *Table notes: Risks to below ground and maintenance workers not shown as these are easily mitigated by the use of PPE.

6.2. Intrusive Works

An intrusive investigation has been designed to effectively target the highest identified risk sources listed in Table 6.1. At this stage the intention is that the planned works would provide sufficient detail to allow identification of any major contamination concerns on site and the formulation of an outline remedial options assessment, if required, or more detailed investigation where necessary.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 28 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

6.3. Analytical Strategy

The development of the initial CSM included consideration of the potential contamination present on site at each identified source. The chosen analysis suite takes into account the findings of the desk study described in Chapters 2 to 4. Samples will be selected for analysis on the basis of historical information about site activities, and olfactory and visual evidence from the arisings observed. The suites for soil and water are described in Tables 6.2 and 6.3 respectively.

Table 6.2: Selection of Laboratory Analytical Suites for Soils Suite Reasoning behind Sampling Regime

 Total Petroleum  All soil samples were analysed for TPH CWG (including BTEX and Hydrocarbons (TPH) MTBE) to provide a detailed breakdown of contaminant profile. and further indicator  Further indicator analysis was undertaken for general contaminants- suite for general Arsenic, cadmium, chromium, lead, mercury, selenium, copper, contaminants. nickel, zinc, boron, cyanide, phenols, PAH (EPA 16).

 Additional analysis  Tetraethyl lead concentrations were determined for one sample taken for limited sampling. from the historical lead pit.

Table 6.3: Selection of Laboratory Analytical Suites for Groundwater and Surface Water Suite Reasoning behind sampling regime

 Arsenic, boron, cadmium, chromium, lead, mercury, A general suite of analysis was selected selenium, copper, nickel, zinc, boron, PAH (EPA 16) to adequately cover the potential soil and TPH CWG including BTEX and MTBE. contaminants described in Table 6.2.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 29 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

7. Site Investigation Methodology

7.1. Supervision

SKM Enviros provided supervision throughout the works undertaken on the 20th and 21st December 2012.. This involved the selection of borehole positions, instruction and co-ordination of drilling subcontractors, logging of investigation arisings, appropriate field testing / monitoring and collection of soil and water samples.

7.2. Summary of Works Undertaken

7.2.1. Selection of Intrusive Locations and Service Clearance

Approximate locations for the majority of exploratory excavations were predetermined based on the findings of the desk study, identification of potential sources of contamination and preliminary qualitative risk assessment. An exploratory plan was sent to Costain for consideration prior to the commencement of intrusive works.

No service plans were provided by Costain. Before commencement of drilling each location was scanned with a cable avoidance tool (CAT). As an additional precaution a hand-dug trial pit was then excavated to a maximum depth of 1.2m below ground level (bgl).

7.2.2. Borehole Drilling

Two ‘rotary open hole’ boreholes were advanced to 11m below ground level using a Pioneer drilling rig, which consists of a hydraulically driven rotary head running on a mast with feed generated by a hydraulic cylinder/chain system. Rotary drilling was completed using water as a flushing medium.

Five window sample boreholes were advanced using a Terrier drilling rig, whereby stainless steel sampling tubes are driven into the ground by percussive means. Plastic sleeves within the sampling tubes allow soil ‘cores’ to be removed in metre intervals allowing the arisings to be logged and sampled. Drilling generally proceeded to between 4 and 5 metres below ground level.

The rotary and window sample borehole locations are shown on Figure 2, along with the positions of six existing boreholes from the 2007 Environ UK investigation.

7.2.3. Soil Sampling

Soil arisings from all excavations were examined for visual and olfactory evidence of contamination and logged in accordance with BS:5930 and EN ISO 14688. Soil logs are provided in Appendix E.

Soil samples were collected at regular intervals, on changes in strata and from any areas where visual or olfactory contamination was observed. Soil samples were obtained from the arisings using a stainless steel trowel. All sampling equipment was cleaned between samples to minimise the potential for cross-contamination. Visible dirt was removed from the stainless steel trowel after the collection of each sample and if further cleaning was necessary the trowel was also washed with detergent (Decon 90).

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 30 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

Soil samples were collected, placed in sealed sample containers (appropriate to the type of analysis to be undertaken and compliant with the laboratory’s UKAS and MCERTS methodologies) and labelled with site specific sample identification. All samples were packed into cold cool boxes with frozen ice packs with chain of custody documentation. Samples were transported to i2 Analytical UK Ltd, a UKAS accredited laboratory. Soil samples were tested to MCERTS standards where appropriate.

7.2.4. Borehole Installation

In order to assess groundwater conditions at a site, monitoring standpipes were installed in both of the rotary boreholes. Each borehole was constructed with a 50mm diameter slotted well screen from 1.2m below ground level to the base at 11m below ground level (response zone), with the screen being surrounded with a gravel filter pack. The wells were completed with 50mm plain well casing, sealed with bentonite clay. The remainder of the annulus was backfilled and completed with raised sealed covers, secured in concrete. The plain well casing and bentonite seal prevents surface water run-off or near surface water, contamination or air from the atmosphere from directly entering the response zone of the standpipe. The standpipes were constructed of HDPE (high density polyethylene) and finished with gas taps to facilitate future monitoring if required.

Additionally, one window sample location (WS102) was installed with a 50mm diameter gas monitoring well. This was constructed in the same way as the rotary borehole wells, with the response zone being positioned between 1 and 3.8m below ground level.

Table 7.1 summarises the installation details of each borehole.

Table 7.1: Borehole Installations Surface Installation Completion Drilled Location Depth Plain Pipe Slotted Pipe Gravel Gas (mbgl) Cover Top Base Top Base Top Base Tap (mbgl) (mbgl) (mbgl) (mbgl) (mbgl) (mbgl) BH101 11.00 0.00 1.20 1.20 11.00 1.20 11.00  Raised BH102 11.00 0.00 1.20 1.20 11.00 1.20 11.00  Raised WS102 3.80 0.00 1.00 1.00 3.80 1.00 3.80  Raised

7.2.5. Groundwater Sampling

Groundwater sampling was undertaken on 3 January 2013. An oil / water interface meter was used to establish groundwater levels in all boreholes (including BHA-F) and to assess the presence of non-aqueous phase liquids. Prior to sampling, wells were purged to ensure representative groundwater samples were obtained. The aim was to purge three well volumes however well recharge rates were slow and this was not possible in practice. Instead, wells were emptied at least once and allowed to partially recharge prior to samples being taken. Samples were taken from all wells which contained water (with the exception of WS102, which was installed to monitor ground gas).

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 31 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

7.2.6. Surface Water Sampling

Water samples were taken from the stream that flows southwards, immediately adjacent to the site’s western boundary. The samples were taken immediately upstream and downstream of the site, as shown on Figure 2.

7.2.7. Ground Gas Monitoring

Ground gas flow rates and concentrations (methane, carbon dioxide, oxygen, hydrogen sulphide) were measured at WS102 on 3rd January 2013. Peak and steady state values were recorded, as were atmospheric pressure and groundwater depth.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 32 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

8. Summary of Ground Conditions

8.1. Ground Conditions

This chapter summarises the ground conditions encountered during the intrusive investigation. Soil logs are provided in Appendix E and the generalised sequence of deposits beneath site is summarised in the following sections.

8.1.1. Made Ground

Made Ground was encountered in all borehole and window sample locations. Generally, Made Ground consisted of soft to firm clay with low but varying proportions of sand and gravel, to depths of between 1 and 1.2m below ground level. There were however two exceptions to this. Firstly, at the location of the in-filled pond (WS102), Made Ground comprised a slightly gravelly clay to 0.5m, beneath which was a clayey gravelly sand to 2.8m. A soft, black fibrous organic clay with a ‘sweet’ decomposition odour was then present between 2.8 and 3.0m below ground level. Secondly, at the location of the historical lead pit (WS105), re-worked clay was present to 1.8m below ground level, which was stained black with a strong fuel odour between 1m and 1.8m. A black, brown and grey sand was then present, again with a fuel odour, to 2.9m below ground level and below this was a 0.2m thick odourless black ‘sludge-like’ silt.

8.2. Natural Ground

Natural strata of firm to stiff slightly gravelly clay were observed in each of the borehole locations, to the base of the exploratory hole. This is consistent with the review of geological maps in advance of intrusive works, which indicated that the site is underlain by Devensian Till (Diamicton).

8.3. Visual and Olfactory Contamination in Soils

As detailed above, the only visual / olfactory evidence of contamination was observed at WS105, where Made Ground was stained black and had a fuel odour to a depth of 2.9m below ground level.

8.4. Groundwater Levels

Drilling arisings from the window sample boreholes were generally dry, with occasional damp or wet strata as noted in the soil logs in Appendix E. It was not possible to observe any water strikes during the rotary drilling as water flush was used as a lubricant.

Groundwater level monitoring was undertaken at all installed monitoring wells following a period of settlement. Free product (non aqueous phase liquid was not present at any location). The results are summarised in Table 8.2.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 33 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

Table 8.2: Groundwater Levels

Depth to Base Groundwater level Well ID (m bgl) mbgl maOD BH101 9.57 5.18 29.68 BH102 9.34 Dry - WS102 3.77 0.05 32.28 BHA 4.83 1.26 30.42 BHB 11.35 Dry - BHC 2.41 0.31 29.35 BHD 4.80 0.33 33.20 BHE 4.09 0.09 31.77 BHF 19.99 Dry -

Using the above data it is not possible to accurately define groundwater flow patterns across the whole site, in part because of uncertainty as to which strata were targeted by boreholes A-F and also because, unexpectedly, BH102 was dry to the drilled depth of 9.5m below ground level, thereby removing the possibility of triangulating groundwater contour lines to this part of the site. It is likely that groundwater within the Till is discontinuous within locally higher permeability layers.

Given the proximity between BHA, BHC, BHD and BHE and the similarity of groundwater levels within each of these standpipes, a groundwater contour plan has been produced by triangulating between these points only. The results are presented in Figure 4, and we have inferred that groundwater flow direction is towards the south west / south, in accordance with the local topography.

8.5. Visual and Olfactory Evidence of Contamination in Groundwater

During groundwater sampling, no visual or olfactory evidence of contamination was noted. Purge water was generally light grey in colour.

8.6. Gas Concentrations

No gas flow was present at WS102 (the borehole was water logged, with water levels above the top of the response zone) and similarly no methane or carbon dioxide were recorded. Gas monitoring was also undertaken at each of the newly installed boreholes (BH101 and BH102) prior to water monitoring and identical results were obtained.

Additionally, when the cover of BHB was removed for water monitoring, the internal head works were observed to be encased in compacted soft clay. When this was removed a hissing noise was noted. As the gas tap was opened a loud rushing of air / gas was heard. The gas monitor was used to establish that a constant negative flow of 8.8 l/hr was being drawn into the well. No gases were detected.

These results provide a snapshot view of ground gas conditions that are not indicative of a problem on site. However, it should be noted that in order for a full gas risk assessment to be carried out it would be standard practice to undertake multiple monitoring visits under varying atmospheric conditions.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 34 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

9. Methodology for Interpretation of Chemical Analysis Data

9.1. Generic Assessment Criteria

In order to put the analytical results into context, the data for the site have in the first instance been screened against generic assessment criteria (GAC) derived from a number of sources. This is known as a Tier 1 assessment. Depending on the results of Tier 1 analysis further tiers of assessment may be deemed necessary. The following information details the selection of generic criteria for the Tier 1 assessment.

9.2. Hazards to Human Health – Soil Contamination

Human health risk assessment has been undertaken in accordance with the approach currently advocated by the Environment Agency (EA) and DEFRA in England and Wales, using the CLEA (Contaminated Land Exposure Assessment) model (Ref. 3). The model evaluates the risks to human health from contaminants via different pathways for a range of land use scenarios based on a detailed review of published research. To date, the Environment Agency has published Soil Guideline Values for five metals / metalloids (arsenic, cadmium, selenium, nickel and mercury) and six organic compounds (benzene, xylene, toluene, ethylbenzene, phenol and for dioxins, furans and dioxin-like PCBs).

For common substances where there is no SGV, SKM Enviros has calculated screening thresholds (GACs) for the standard CLEA land uses using the current CLEA methodology and model (version 1.06). The derivation of SKM Enviros GAC, including that for petroleum hydrocarbons, is fully detailed within Appendix F. All GACs are appropriate for industrial / commercial land uses.

9.2.1. Averaging Areas and Data Handling

Consideration has been given to the most appropriate method of grouping soils data. This can include separating the data spatially or by the different strata underlying the site. The required approach may differ for different contaminants as some may be associated with particular current or historical activities carried out in a particular location while others may be associated with materials (such as made ground) brought on to the site.

At the GPSS Backford South site intrusive locations were selected to target individual potential contaminant sources. Therefore, it is not considered appropriate to group the data spatially or by strata to undertake statistical analysis. Guideline screening values are therefore compared to discrete samples for Tier 1 assessment.

9.2.2. Physio-chemical Soil Properties – Soil Organic Matter

Certain soil properties will greatly affect the mobility, migration and availability of contaminants. It is important to assess these properties prior to Tier 1 screening in order that the results can be interpreted in the correct context. Of particular relevance to potential hydrocarbon contamination is the soil organic matter (SOM). This particularly affects the exposure pathways involving absorption and inhalation of hydrocarbon vapours and the leachability of these substances.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 35 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

A total of 10 Made Ground samples were assessed for total organic carbon, which is assumed to represent 58% of the total amount of organic matter present (in line with Environment Agency guidance, (Ref. 10). The average SOM value is 2.19%. GACs based on 1% organic matter have been used for the assessment; as organic content increases, the mobility of organic contaminants decreases therefore 1% is considered conservative for a Tier 1 assessment.

9.3. Potential Contamination of Controlled Waters

The consideration of water pollution has been made in the specific context of the site and the risk it presents to controlled waters.

9.3.1. Environmental Quality Standards (EQS)

EQS are concentrations below which it is generally accepted that a contaminant will have no effect on the aquatic environment. This assessment uses EQS appropriate for the protection of aquatic life, as provided in the Environment Agency’s Chemical Standards Database (Ref. 11). Where more than one EQS are available (for example when different values are calculated to be protective of differing species), the most conservative value is used. It should be noted that if an EQS is exceeded, this does not necessarily mean that there is a significant impact on aquatic organisms or plants. Further studies would be required to confirm the extent of any impact.

Some EQS values are dependent on the hardness of the receiving water(s). For the purposes of this investigation, the receiving water is assumed to be the stream adjacent to the western boundary and hardness values have been obtained from locations immediately upstream and downstream of the site. The average value from these two locations, as measured as CaCO3, is 204.5 mg/l.

9.3.2. Criteria for Hydrocarbons

EQS (and drinking water standards) for petroleum hydrocarbons refer to visual and olfactory evidence or are based on a determination of the ‘effect’ on the receiving ecosystem. Therefore, there is no absolute value available for comparison of laboratory data.

A Tier 1 screening value of 0.5 mg/l is proposed (for kerosene/diesel/fuel oil), based on the following:

 An Intervention Value of 0.6 mg/l for mineral oil in groundwater cited in the Dutch government guidelines (Ref. 12);

 Remediation criteria for benzene of 0.3 mg/l and for ethyl benzene of 0.7 mg/l for freshwater aquatic life cited in Canadian Environmental Quality Criteria (Ref. 13); and,

 A 48 hour “no-observed effect loading rate” to the water flea (Daphnia magna) due to kerosene contaminated water of between 0.3 and 0.9 mg/l (depending upon the type of hydrocarbon measured – Ref. 14).

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 36 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

10. Review of Laboratory Analysis

10.1. Chemical Soil Analysis

A total of ten Made Ground soil samples were submitted for analysis of a range of metals, hydrocarbons (including BTEX and MTBE), and polycyclic aromatic hydrocarbons (see Table 10.1). The borehole locations are shown in Figure 2. Chemical results are presented in Appendix G in tabular form. The full analytical certificates are presented in Appendix H.

The preliminary risk screening exercise, comparing data against GACs, is considered to be a Tier 1 assessment and gives an indication of Contaminants of Concern. As it is proposed that the site is to be sold for continued commercial / industrial use (as a fuel management facility) the Tier 1 risk screening will use this end use as a basis for the assessment.

Table 10.1: Sample Selection & Analysis Analysis

Location Sample Source Target ID Depth (m) Material Lead PAH, MTBE BTEX, Screen Metals, cyanide phenols Asbestos Tetraethyl TPH CWG,

General Made Ground / site BH101 0.5 MG    coverage General Made Ground / site BH102 0.4 MG    coverage Above ground fuel storage WS101 0.2 MG    tank In-filled pond / in-fill material: WS102 0.4 NG     Near surface material In-filled pond / in-fill material: WS102 2.9 MG fibrous organic material with    ‘sweet decomposition’ odour Fuel spill in adjacent workshop WS103 0.2 MG    – near-surface level Fuel spill in adjacent workshop WS103 0.5 MG    – foundation level Burning area – near-surface WS104 0.2 MG    Made Ground WS105 0.5 MG Lead pit – infill material     WS105 1.5 MG Lead pit – fuel-impacted soils    

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 37 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

10.1.1. Analysis of Inorganic Contaminants

Results of the initial screening of inorganic contaminants are illustrated in Table 10.2.

Table 10.2: Inorganic Parameters in Soils (mg/kg) GAC – Above Potential Analyses Location of Commercial / GAC Min Max Contaminant (No.) Exceedence(s). industrial (No.) Arsenic 10 640 - 4.1 12 Water soluble boron 10 192,495 - 0.3 2.3 Cadmium 10 230 - 0.4 3.5 Total chromium 10 30,356 - 17 38 Copper 10 71,742 - 10 45 Lead 10 750 1 20 1,100 WS101, 0.2m Mercury 10 368 - <0.3 <0.3 Nickel 10 1,800 - 13 53 Selenium 10 13,000 - <1 <1 Zinc 10 665,453 - 44 1,500

As shown, the GAC for lead was exceeded at WS101 in near surface soils. This suggests that fuel containing a lead additive may have been stored in the gantry-mounted storage tank or, possibly, that lead is present due to an historical fuel leak or spill from a vehicle. There were, however, no visual or olfactory indications that the soils in this area were impacted by fuels.

In addition to the above each sample was tested for cyanide and concentrations were consistently below analytical detection limits. Two samples (WS102.0.4m and WS105, 0.5m) were screened for asbestos, which was found to be absent.

10.1.2. Analysis of Organic Soil Contamination

As shown in Appendix G, concentrations of phenols, BTEX and MTBE were below analytical detection limits in all samples. Similarly, PAH were below detection limits in all samples except WS102 at 2.9m, which contained very low concentrations of six PAH. Included within this group are three PAH which are classed as carcinogens – chrysene, benzo(b)fluoranthene and benzo(a)pyrene. However, none of these compounds were present in concentrations greater than their respective GAC, as shown in Table 10.3.

Table 10.3 Carcinogenic PAH Concentrations in WS102, 2.9m GAC – Concentration Contaminant Commercial / mg/kg industrial mg/kg Chrysene 0.16 137 Benzo(b)fluoranthene 0.22 141 Benzo(a)pyrene 0.13 14

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 38 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

TPH were detected in three sample locations. Some individual hydrocarbon components can pose a risk to human health, due to their carcinogenic nature. There is also an additional non-cancer risk to human health posed by hydrocarbon mixtures as a whole. In order to assess these two aspects of the toxicology of hydrocarbons, individual fractions of TPH have been assessed and the TPH mixture assessed separately. The assessment approach is explained fully in Appendix F. TPH calculation sheets are provided in Appendix I and a summary of the results is provided in Table 10.4.

Table 10.4 Total Petroleum Hydrocarbons (mg/kg) Fraction- WS101 WS102 WS105 TPH Fraction Specific GAC 0.2m 2.9m 1.5m Aliphatic >5–6 5,661 < 0.1 < 0.1 < 0.1 Aliphatic >6-8 12,038 < 0.1 < 0.1 < 0.1 Aliphatic >8–10 2,679 < 0.1 < 0.1 < 0.1 Aliphatic >10-12 80,262 < 1.0 < 1.0 150 Aliphatic >12-16 49,075 22 < 2.0 1400 Aliphatic >16-21 3,813,654 180 34 2,000 Aliphatic >21-35 3,813,654 100 280 660 Aromatic >6–7 3,417 < 0.1 < 0.1 < 0.1 Aromatic >7–8 3,190 < 0.1 < 0.1 < 0.1 Aromatic >8–10 4,054 < 0.1 < 0.1 < 0.1 Aromatic >10–12 17,921 < 1.0 < 1.0 48 Aromatic >12–16 48,156 3 < 2.0 680 Aromatic >16-21 57,205 44 < 10 1000 Aromatic >21–35 57,205 62 48 380 Total Petroleum Hydrocarbons 414 379 6319 Mixture-Specific GAC 155,849 271,326 87,557

As shown, the concentrations of individual TPH fractions are very low (where detected) in comparison to fraction specific GAC. Similarly, when the mixture specific blend of hydrocarbons in each sample are assessed collectively, TPH concentrations are much lower than the mixture- specific assessment criteria.

It should be noted that sample a sample from WS105 (1.5m) was also assessed for tetra-methyl and tetra-ethyl lead, which was not present at concentrations greater than the analytical detection limit of 0.01 mg/kg.

10.1.3. Groundwater and Surface Water Chemical Analysis

The locations of groundwater monitoring wells are illustrated in Figure 2. Groundwater analytical results are presented in full in Appendix J and in the certificate of analysis is provided in Appendix K. One round of groundwater analysis was undertaken on 3 January 2012 and all boreholes that contained sufficient volumes of groundwater were sampled.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 39 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

EQS, where available, were used to assess the significance of the concentrations of contaminants in groundwater from boreholes BH101, BHA, BHC, BHD, and BHE (as outlined in Section 9.2.2.). Surface water samples from the stream on the western boundary were also assessed.

Concentrations of PAH, BTEX, MTBE and TPH were below analytical detection limits in all samples. Concentrations of toxic metals, where detected, were consistently below relevant quality standards, as shown in Table 10.5 below. Additionally, no significant variation in toxic metal concentrations were observed between upstream and downstream locations, with concentrations of some metals being greater upstream, and some being greater downstream.

Table 10.5: Toxic metal concentrations in Groundwater and Surface Water Contaminant Units No. of analyses EQS2 Max. Conc Arsenic µg/l 7 50 13 Boron µg/l 7 2000 70 Cadmium µg/l 7 5 <0.1 Chromium µg/l 7 50 2.1 Copper3 µg/l 7 10 9.3 Lead µg/l 7 20 6.3 Mercury µg/l 7 1 <0.5 Nickel3 µg/l 7 200 7.9 Selenium4 µg/l 7 - <4 Zinc2 µg/l 7 300 55 Notes: 1. Samples were taken from the following locations, as shown on Figure 2: BH101, BHA, BHC, BHD, BHE, Upstream, Downstream 2. Freshwater EQS values have been used as defined by the Water Framework Directive for the protection of aquatic life. 3. EQS is conservative value applicable to the protection of sensitive freshwater species (e.g. salmonid fish). 4. No relevant EQS available

10.2. Summary of Analytical Data

Ten samples of Made Ground were assessed for a range of organic and inorganic potential contaminants of concern. Contaminant concentrations were below relevant screening values across the site, except at WS101, which was drilled to target an above ground storage tank, (assumed to have once contained fuel). At this location, lead concentrations in near surface soils were 1100 mg/kg, against a generic assessment criteria value of 750 mg/kg.

Samples of groundwater were obtained from boreholes positioned in proximity to the fuel storage tanks, the manifold area / pump house and across the wider site area. Samples were also obtained from the stream that runs adjacent to the western boundary, from upstream and downstream locations. No organic groundwater or surface water contamination was detected. Although inorganic contaminants were detected they were consistently below relevant quality standards in both groundwater and surface water samples.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 40 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

11. Updated Environmental Risk Assessment

Observations of ground conditions made during the site investigation have not altered the potential source – pathway – receptor linkages described by the conceptual site model in Section 5. In light of observations of contamination and chemical data obtained for soil, groundwater and surface water samples, the risks associated with the potential contamination sources have been re- assessed. The re-assessment is consistent with the methodology outlined in Section 5 and an updated risk assessment table is presented below, where risks have been updated based on the site investigation data, the previous assessment is presented in brackets.

Table 11.1: Updated potential environmental risks for current / future commercial industrial use and during maintenance or below ground works Potential Potential Potential Potential Associated Likelihood of Risk / Pathways to Source Pollutant Receptors Hazard [severity] Occurrence Significance Receptors S1 Hydrocarbons Humans Health Hazard All soil samples Decommissioned (aviation fuel) analysed for organic semi buried fuel contaminants were storage tanks below the appropriate GACs for commercial / industrial end use. A. Current / P1. Direct Minor Unlikely Negligible future use contact, (initial severity No elevated (preliminary ingestion, Medium which concentrations of assessment inhalation assumed hydrocarbons Low) contaminant detected in shallow concentrations of soils significance) B. Below ground P1 – Direct Minor Unlikely Negligible maintenance contact, (initial severity Mild No elevated (preliminary workers ingestion, which assumed concentrations of assessment inhalation contaminant hydrocarbons Low) concentrations of detected in shallow significance) soils Controlled Waters Environmental All potential impact hydrocarbon contaminants in water samples analysed were below the appropriate WQS. C. Groundwater P2 and P3. Impact on Unlikely Negligible Principal Aquifer Leaching of groundwater quality No elevated (preliminary contamination concentrations of Minor assessment from soils by hydrocarbons Moderate) rainwater (initial severity detected in infiltration and Severe which groundwater migration assumed underlying the site. through contaminant groundwater concentrations of significance)

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 41 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

Potential Potential Potential Potential Associated Likelihood of Risk / Pathways to Source Pollutant Receptors Hazard [severity] Occurrence Significance Receptors S1 Hydrocarbons D. Surface water P3. Vertical and Impact on surface Unlikely Negligible Decommissioned (aviation fuel) Drain on western lateral migration water No elevated (preliminary semi buried fuel in groundwater concentrations of continued boundary Minor assessment storage tanks hydrocarbons (initial severity Moderate) detected in continued Severe which groundwater assumed underlying the site or contaminant surface waters. concentrations of significance) P4. Surface Impact on surface Unlikely Negligible water runoff No elevated water (preliminary Minor concentrations of assessment hydrocarbons (initial severity Low) detected in surface Medium which waters. assumed contaminant concentrations of significance) E. Buildings and P5. Direct Damage to Unlikely Negligible services contact No elevated buildings and (preliminary contaminant services assessment Minor concentrations Negligible) identified in the soil (initial severity Mild samples tested which assumed contaminant concentrations of significance) P6. Vapour Damage to Low Likelihood Negligible accumulation No elevated services and (preliminary structures contaminant assessment concentrations Minor Moderate) identified in the soil (initial severity samples tested, Severe which although odours were assumed noted locally. contaminant concentrations of significance) S2. Hydrocarbons Humans Health Hazard All soil samples Decommissioned (aviation fuel) analysed for organic pump house and contaminants were associated pipe below the appropriate network GACs for commercial / industrial end use A. Current / P1. Direct Minor Unlikely Negligible future use contact, (initial severity No elevated (preliminary ingestion, Medium which concentrations of assessment inhalation assumed hydrocarbons Low) contaminant detected in shallow concentrations of soils significance) B. Below ground P1 – Direct Minor Unlikely Negligible maintenance contact, (initial severity Mild No elevated (preliminary workers ingestion, which assumed concentrations of assessment inhalation contaminant hydrocarbons Low) concentrations of detected in shallow significance) soils

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 42 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

Potential Potential Potential Potential Associated Likelihood of Risk / Pathways to Source Pollutant Receptors Hazard [severity] Occurrence Significance Receptors S2. Hydrocarbons Controlled Waters Environmental All potential Decommissioned (aviation fuel) impact hydrocarbon pump house and continued contaminants in water associated pipe samples analysed network were below the continued appropriate WQS. C. Groundwater P2 and P3. Impact on Unlikely Negligible Principal Aquifer Leaching of No elevated groundwater quality (preliminary contamination concentrations of Minor assessment from soils by hydrocarbons (initial severity Moderate / rainwater detected in Medium which Low) infiltration and groundwater assumed migration underlying the site. contaminant through concentrations of groundwater significance) D. Surface water P3. Vertical and Impact on surface Unlikely Negligible Drain on western lateral migration water No elevated (preliminary in groundwater concentrations of boundary Minor assessment hydrocarbons (initial severity Moderate / detected in Medium which Low) groundwater assumed underlying the site or contaminant surface waters. concentrations of significance) P4. Surface Impact on surface Unlikely Negligible water runoff No elevated water (preliminary concentrations of Minor assessment hydrocarbons (initial severity Moderate / detected in surface Medium which Low) waters. assumed contaminant concentrations of significance) E. Buildings and P5. Direct Damage to Unlikely Negligible services contact buildings and No elevated (preliminary contaminant services assessment concentrations Minor Negligible) identified in the soil (initial severity Mild samples tested which assumed contaminant concentrations of significance) P6. Vapour Damage to Low Likelihood Negligible accumulation No elevated services and (preliminary structures contaminant assessment concentrations Minor Moderate) identified in the soil (initial severity samples tested, Severe which although odours were assumed noted locally. contaminant concentrations of significance)

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 43 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

Potential Potential Potential Potential Associated Likelihood of Risk / Pathways to Source Pollutant Receptors Hazard [severity] Occurrence Significance Receptors S3. Hydrocarbons Humans Health Hazard All soil samples Decommissioned analysed for organic above ground contaminants were fuel / oil storage below the appropriate tanks GACs for commercial / industrial end use. However, lead contamination has been confirmed at WS101 beneath the loading gantry (assessed separately see final row) A. Current / P1. Direct Minor Unlikely Negligible future use contact, (initial severity No elevated (preliminary ingestion, Medium which concentrations of assessment inhalation assumed hydrocarbons Low) contaminant detected in shallow concentrations of soils significance) B. Below ground P1 – Direct Minor Unlikely Negligible maintenance contact, (initial severity Mild No elevated (preliminary workers ingestion, which assumed concentrations of assessment inhalation contaminant hydrocarbons Low) concentrations of detected in shallow significance) soils Controlled Waters Environmental All analysis results for impact water samples were below the appropriate WQS. C. Groundwater P2 and P3. Impact on Unlikely Negligible Principal Aquifer Leaching of groundwater quality No elevated (preliminary contamination contaminant Minor assessment from soils by concentrations (initial severity Moderate / rainwater detected in Medium which Low) infiltration and groundwater assumed migration underlying the site. contaminant through concentrations of groundwater significance)

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 44 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

Potential Potential Potential Potential Associated Likelihood of Risk / Pathways to Source Pollutant Receptors Hazard [severity] Occurrence Significance Receptors S3. Hydrocarbons D. Surface water P2 and P3. Impact on Unlikely Negligible Decommissioned continued Drain on western Leaching of groundwater quality No elevated (preliminary contamination contaminant above ground boundary Minor assessment from soils by concentrations fuel / oil storage (initial severity Moderate / rainwater detected in tanks continued Medium which Low) infiltration and groundwater assumed migration underlying the site or contaminant through adjacent surface concentrations of groundwater water. significance) P4. Surface Impact on surface Unlikely Negligible water runoff No elevated water (preliminary Minor contaminant assessment concentrations (initial severity Low) detected in surface Medium which water. assumed contaminant concentrations of significance) E. Buildings and P5. Direct Damage to Unlikely Negligible services contact No elevated buildings and (preliminary contaminant services assessment Minor concentrations Negligible) identified in the soil (initial severity Mild samples tested which assumed contaminant concentrations of significance) P6. Vapour Damage to Low Likelihood Negligible accumulation No elevated services and (preliminary structures contaminant assessment concentrations Minor Moderate) identified in the soil (initial severity samples tested, Severe which although odours were assumed noted locally. contaminant concentrations of significance) S5. Historical Hydrocarbons, Humans Health Hazard All analysis results for burning area PAH soil samples were below the appropriate GACs for commercial / industrial end use A. Current / P1. Direct Minor Unlikely Negligible future use contact, (initial severity No elevated (preliminary ingestion, Medium which concentrations of assessment inhalation assumed contaminants detected Low) contaminant in shallow soils concentrations of significance) B. Below ground P1 - Direct Minor Unlikely Negligible maintenance contact, (initial severity No elevated (preliminary workers ingestion, Medium which concentrations of assessment inhalation assumed contaminants detected Moderate / contaminant in shallow soils Low) concentrations of significance)

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 45 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

Potential Potential Potential Potential Associated Likelihood of Risk / Pathways to Source Pollutant Receptors Hazard [severity] Occurrence Significance Receptors S5. Historical Hydrocarbons, Controlled Waters Environmental All analysis results for burning area PAH continued impact water samples were continued below the appropriate WQS. C. Groundwater P2 and P3. Impact on Unlikely Negligible Principal Aquifer Leaching of No elevated groundwater (preliminary contamination Minor contaminant assessment from soils by concentrations (initial severity Low) rainwater detected in Medium which infiltration and groundwater assumed migration underlying the site. contaminant through concentrations of groundwater significance) D. Surface water P2 and P3. Impact on surface Unlikely Negligible Leaching of No elevated Drain on western water (preliminary contamination contaminant boundary Minor assessment from soils by concentrations (initial severity Low) rainwater detected in Medium which infiltration and groundwater assumed migration underlying the site or contaminant through adjacent surface concentrations of groundwater water. significance) P4. Direct run- Impact on surface Unlikely Negligible off No elevated water (preliminary Minor contaminant assessment concentrations (initial severity Moderate / detected in surface Medium which Low) water. assumed contaminant concentrations of significance) S6. In-filled pond Ground gases Humans Health Hazard No elevated gas (methane, detected on carbon dioxide) monitoring visit A. Current / P1. Inhalation Minor Unlikely Negligible future use (initial severity Elevated gas (preliminary Severe which concentrations not assessment assumed detected Moderate / contaminant Low) concentrations of significance) B. Below ground P1. Inhalation Minor Unlikely Negligible maintenance (initial severity Elevated gas (preliminary workers Severe which concentrations not assessment assumed detected Moderate) contaminant concentrations of significance)

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 46 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

Potential Potential Potential Potential Associated Likelihood of Risk / Pathways to Source Pollutant Receptors Hazard [severity] Occurrence Significance Receptors S6. In-filled pond Ground gases E. Buildings and P6. vapour Damage to Unlikely Negligible continued (methane, services accumulation services Elevated gas (preliminary carbon dioxide) Minor concentrations not assessment continued (initial severity detected Moderate / Severe which Low) assumed contaminant concentrations of significance) S7. Historical Hydrocarbons, Humans Health Hazard All analysis results for Lead Pit tetra-ethyl-lead soil samples were (tank residues) below the appropriate GACs for commercial / industrial end use A. Current / P1. Direct Minor Unlikely Negligible future use contact, (initial severity No elevated (preliminary ingestion, Medium which concentrations of assessment inhalation assumed contaminants detected Low) contaminant in shallow soils concentrations of significance) B. Below ground P1 - Direct Minor Unlikely Negligible maintenance contact, (initial severity No elevated (preliminary workers ingestion, Medium which concentrations of assessment inhalation assumed contaminants detected Moderate / contaminant in shallow soils Low) concentrations of significance) Controlled Waters Environmental All analysis results for impact water samples were below the appropriate WQS. C. Groundwater P2 and P3. Impact on Unlikely Negligible Principal Aquifer Leaching of groundwater No elevated (preliminary contamination contaminant Minor assessment from soils by concentrations (initial severity Moderate / rainwater detected in Medium which Low) infiltration and groundwater assumed migration underlying the site. contaminant through concentrations of groundwater significance) D. Surface water P3. Migration Impact on surface Unlikely Negligible through No elevated Drain on western water (preliminary boundary groundwater Minor contaminant assessment base flow concentrations (initial severity Low) detected in Medium which groundwater assumed underlying the site or contaminant adjacent surface concentrations of water. significance)

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 47 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

Potential Potential Potential Potential Associated Likelihood of Risk / Pathways to Source Pollutant Receptors Hazard [severity] Occurrence Significance Receptors S7. Historical Hydrocarbons, E. Buildings and P5. Direct Damage to Unlikely Negligible Lead Pit tetra-ethyl-lead services contact or services No elevated (preliminary P6.vapour contaminant continued (tank residues) Minor assessment accumulation concentrations continued (initial severity Low) identified in the soil Medium which samples tested. assumed contaminant concentrations of significance) Elevated lead lead B. Below Ground P1 - Direct Medium Low likelihood Moderate / concentration at and Maintenance contact, (not included in lead contamination Low WS101 beneath workers ingestion, preliminary risk has been confirmed at (Could be the loading inhalation assessment as no WS101 beneath the reduced to gantry known source) loading gantry above Negligible by the assessment utilising criteria. Disturbance appropriate of the ground is likely, PPE / risk but any exposure assessment) during groundworks will be very short term (acute rather than chronic). Contamination is thought to be very localised as no other elevated concentrations were encountered

11.1. Updated Risk Assessment Summary

The updated risk assessment has taken into consideration the reasoning behind the preliminary risk assessment and the findings of the site investigation in order reassess the risks for the site based on continued or future commercial industrial use (as a fuel management facility). On this basis, the updated risk assessment did not identify any risks greater than Negligible, with the exception of the risk to below ground workers from lead which is assessed as Moderate / Low, although this could be easily reduced to negligible by use of appropriate PPE and risk assessment.

It should be noted that the assessment is only based on a relatively small number of sampling locations and one round of gas monitoring, as such there is the possibility that localised areas of contamination remain unidentified or that gas concentrations fluctuate at the site. However, there is a good level of confidence from the information gathered that there is not significant and widespread contamination across the site.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 48 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

12. Overall Land Quality and Suitability for Use

GPSS Backford South is a mothballed fuel pumping station and storage facility which was operational between circa 1939 and the early 1990s. Storage and handling of hydrocarbons was the primary function of the site with large quantities being stored and passing through the site.

Groundwater, surface water and ecological sensitivities for the site are assessed as Moderately High, Moderately High and Low respectively.

Initially a number of potentially significant risks from potential sources of contamination were identified based on the site use, history and sensitivity. Potential sources of contamination were associated with its historical use as a fuel storage facility. These include large capacity part-buried fuel storage tanks, oil pipeline and pumping station infrastructure, above ground (small capacity) fuel storage tanks, transformers associated with an electrical sub-station and a switch room, an historical burning area, an in-filled pond and an historical lead pit.

A targeted intrusive investigation was undertaken in order to refine the preliminary risk assessment. With the exception of one anomalous lead concentration in one soil sample the site investigation did not identify any contaminant concentrations in soils or water that were greater than appropriate generic assessment criteria for commercial / industrial use. Specifically no hydrocarbon contaminants were identified above GAC threshold values. On this basis the updated risk assessment assessed all risks to be Negligible with the exception of the risk to below ground workers from lead which is assessed as Moderate / Low, although this could be easily reduced to Negligible by use of appropriate PPE and risk assessment.

On the basis of the intrusive investigations the preliminary risk assessment was updated and all risks were assessed as Negligible.

Overall the site is considered to be suitable for continued or future commercial / industrial use (as a fuel management facility).

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 49 GPSS Portfolio – Backford South Phase One and Two Land Quality Assessment – Final

13. References

1) Environ UK Ltd, 2007. Environmental Site Assessment. Backford Petroleum Storage Depot, Caughall Lane, Backford, Chester, Cheshire. Ref. R67C12251, Issue 2.

2) Department for Environment, Food and Rural Affairs, Environmental Protection Act 1990; Part 2A Contaminated Land Statutory Guidance. April 2012.

3) Department for Environment, Food and Rural Affairs / Environment Agency, 2004. Model Procedures for the Management of Land Contamination, CLR11.

4) Ministry of Defence, Legislation to enable sale of the Government Pipeline and Storage System [information document], Reference DMC 00478 12/13. 04/11

5) British Geological Survey online maps, www.bgs.ac.uk. (Accessed December 2012)

6) Environment Agency, 2012. What’s In Your Backyard?”. Available from http://www.environment-agency.gov.uk/, (accessed November 2012).

7) Department for Environment Food & Rural Affairs, Environment Agency and Institute of Environmental Health, 2000. Guidelines for Environmental Risk Assessment and Management. HMSO.

8) Construction Industry Research and Information Association (CIRIA), 2011. Contaminated Land Risk Assessment. A Guide to Good Practice. CIRIA C552.

9) Defence Estates, 2007. Contaminated Land Management: Land Quality Assessment (LQA) Management Guide, PG 01/07.

10) Environment Agency, 2006. Evaluation of Models for Predicting Plant Uptake of Chemicals in Soil. Science Report SC050021/SR.

11) Environment Agency, 2011. Chemical Standards. Available from http://evidence.environment- agency.gov.uk/ChemicalStandards/home.aspx. (Accessed January 2013).

12) Ministry of Housing, Spatial Planning and Environment, 1994. Intervention values and target values – soil quality standards

13) Canadian Council of Ministers of the Environment, 1991. Interim Canadian Environmental Quality Criteria for Contaminated Sites, Ref CCME EPC-CS34.

14) Environment Agency, 1999. Review of Crude Oil Derived Petroleum Products in the Aquatic Environment. Draft R&D Technical Report P75/i688.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx PAGE 50 GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

FIGURES

Figure 1: Site Location Plan Figure 2: Site Layout, Potential Contaminant Sources and Exploratory Hole Locations Figure 3: Conceptual Site Model Figure 4: Groundwater Contour Plan

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

APPENDICES

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx

GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

Appendix A Site Photographs

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx

GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

Photograph 1: General view of site, showing two of the part-buried fuel tanks

Photograph 2: Broken fuel bottles in northern workshop, with staining to floor

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx

GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

Photograph 3: 4.5m3 Diesel tank (redundant) in south west of site

Photograph 4: Perimeter drainage channel and bund in south west corner, with pooled water

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx

GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

Photograph 5: Manifold area (with bund to left and buried pump house beneath mound to the right. Interceptor visible beyond the manifold area

Photograph 6: View across site showing mounds of part-buried fuel storage tanks SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx

GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

Photograph 7: Electricity sub-station on southern boundary. Perimeter drainage channel / bund also visible

Photograph 8: Fuel tank on overhead gantry

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx

GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

Photograph 9: Staining to hardstanding below gantry fuel tank

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx

GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

Appendix B Public Register Information

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx

GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

Appendix C Historical Maps

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx

GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

Appendix D Risk Assessment Methodology

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx

GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

Preliminary Risk Assessment Methodology

Risk assessment is the process of collating known information on a hazard or set of hazards in order to estimate actual or potential risks to receptors. The receptor may be human health, a water resource, a sensitive local ecosystem or even future construction materials. Receptors can be connected with the hazard under consideration via one or several exposure pathways (e.g. the pathway of direct contact). Risks are generally managed by isolating or removing the hazard, isolating the receptor, or by intercepting the exposure pathway. Without the three essential components of a source (hazard), pathway and receptor, there can be no risk. Thus, the mere presence of a hazard at a site does not mean that there will necessarily be attendant risks. The following risk assessment thus focuses on those parts of the site where hazards or potential hazards have been identified and is not general to the whole site.

Hazards

Potential sources of contamination are identified for the site, based on a review of the current and previous site uses. Not only the nature but also the likely extent of any contamination is considered, e.g. whether such contamination is likely to be localised or widespread.

Receptors

The varying effects of a hazard on individual receptors depends largely on the sensitivity of the target. Receptors include any people, animal or plant population, or natural or economic resources within the range of the source which are connected to the source by the transport pathway. Receptors can, in addition, extend to remediation processes and future construction materials that may be adversely affected by on-site contamination. In general, however, receptors can be divided into a number of groups depending on the final use of the site.

Pathways

The mere presence of contamination does not infer a risk. The exposure pathway determines the dose delivered to the receptor and the effective dose determines the extent of the adverse effect on the receptor. The pathway which transports the contaminants to the receptor or target generally involves conveyance via soil, water or air.

Exposure Assessment

By considering the source, pathway and receptor, an assessment is made for each contaminant on a receptor by receptor basis with reference to the significance and degree of the risk. In assessing this information, a measure is made of whether the source contamination can reach a receptor, determining whether it is of a major or minor significance. The exposure risks are assessed against the present site conditions.

A preliminary risk assessment has been undertaken for these potential source-pathway-receptor linkages to identify potentially unacceptable risks on a qualitative basis. This approach is based on DEFRA and CIRIA guidance on risk assessment and Model Procedures. Risk is based on a consideration of both:

The likelihood of an event (probability); [takes into account both the presence of the hazard and receptor and the integrity of the pathway].

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx

GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

The severity of the potential consequence [takes into account both the potential severity of the hazard and the sensitivity of the receptor].

In order to then determine the risk to the identified receptor, both the likelihood and severity of the potential hazard is input into a risk assessment matrix as follows:

Consequence Severe Medium Mild Minor/Negligible High Very high risk High risk Moderate risk Moderate/Low (Likelihood) Probability Likelihood risk Likely High risk Moderate risk Moderate/Low risk Low risk Low Moderate risk Moderate/Low risk Low risk Negligible risk Likelihood Unlikely Moderate/Low risk Low risk Negligible risk Negligible risk

Under such a classification system the following categorisation of risk has been developed and the terminology adopted as follows:

Term Description Very high risk Severe harm to a receptor may already be occurring OR a high likelihood that severe harm will arise to a receptor, unless immediate remedial action works / mitigation measures are undertaken. High risk Harm is likely to arise to a receptor, and is likely to be severe, unless appropriate remedial actions / mitigation measures are undertaken. Remedial works may be required in the short term, but likely to be required over the long term. Moderate risk Possible that harm could arise to a receptor but low likelihood that such a harm would be severe. Harm is likely to be medium. Some remedial works may be required in the long term. Moderate / low Possible that harm could arise to a receptor, but where a combination of likelihood and risk consequence results in a risk that is above low, but is not of sufficient concern to be classified as medium. It can be driven by cases where there is an acute risk which carries a severe consequence, but where the exposure is unlikely. Low risk Possible that harm could arise to a receptor. Such harm would at worse normally be mild. Negligible risk Low likelihood that harm could arise to a receptor. Such harm unlikely to be any worse than mild.

The colour coding for each risk category is used in the risk assessment summary table.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx

GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

Classification of Consequences

Classification Definition

Severe  Acute risks to human health

 Short-term risk of pollution of sensitive water resource (e.g. major spillage into controlled waters)

 Impact on controlled waters e.g. large scale pollution or very high levels of contamination

 Catastrophic damage to buildings or property 9e.g. explosion causing building collapse)

 Ecological system effects – irreversible adverse changes to a protected location. Immediate risks.

Medium  Chronic risks to human health

 Pollution of sensitive water resources (e.g. leaching of contaminants into controlled waters)

 Ecological system effects – substantial adverse changes to a protected location.

 Significant damage to buildings, structures and services (e.g. damage rendering a building unsafe to occupy, such as foundation damage)

Mild  Non-permanent health effects to human health

 Pollution of non-sensitive water resources (e.g. pollution of non-classified groundwater)

 Damage to buildings, structures and services (e.g. damage rendering a building unsafe to occupy, such as foundation damage)

 Substantial damage to non-sensitive environments (unprotected ecosystems e.g. crops)

Minor/Negligible  Non-permanent health effects to human health (easily prevented by appropriate use of PPE

 Minor pollution to non-sensitive water resources

 Minor damage to non-sensitive environments (unprotected ecosystems e.g. crops)

 Easily repairable effects of damage to buildings, structures, services or the environment (e.g. discoloration of concrete, loss of plants in a landscaping scene).

Classification Definition

High Likelihood An event is very likely to occur in the short term, and is almost inevitable over the long term OR there is evidence at the receptor of harm or pollution

Likely It is probably that an event will occur. It is not inevitable, but possible in the short term and likely over the long term

Low Likelihood Circumstances are possible under which an event could occur. It is by no means certain that even over a longer period such an event would take place, and less likely in the short term

Unlikely It is improbable that an event would occur even in the very long term

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx

GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

Appendix E Exploratory Hole Logs

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx

GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

Appendix F Derivation of SKM Enviros Generic Assessment Criteria (GAC)

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx

GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

Screening Values for Chronic Risks to Human Health from Contaminants in Shallow Soil

Introduction

The standard methodology for assessment of chronic risks to human health from was originally produced in 2002 and titled the “Contaminated Land Exposure Assessment” (CLEA) methodology. This comprised a number of documents providing information on how to assess the exposure to soil contaminants from typical behaviour as well as providing UK data such as standard body weights, soil ingestion, and vegetable consumption rates.

Information on toxicology was also provided for a number of substances and soil guideline values (SGVs) were produced by using the toxicological data as well as data collated on chemical and physical properties of these substances.

Revisions to the CLEA Model

Between August 2008 and January 2009 the Environment Agency reviewed and made a large number of changes to the CLEA methodology and exposure data. As part of this the Environment Agency:

 Withdrew all the SGV reports;

 Issued draft and final new versions of the CLEA methodology (SR3), formerly called CLR10, and the CLEA model;

 Issued draft and final versions of the methodology used to calculate the toxicity data entered into the model (SR2), formerly called CLR9; and

 Stated that the current TOX reports will be replaced by new ones by March 2009 (old reports to be withdrawn as each new one is issued).

Since then the Environment Agency has begun publishing revised SGV and TOX reports on a rolling programme. In October 2009 this comprised eleven revised SGV and TOX reports substances including five for metals and metalloids (arsenic, cadmium, selenium, nickel and mercury) and six for organics (benzene, xylene, toluene, ethylbenzene, phenol and for dioxins, furans and dioxin-like PCBs).

The revised CLEA SGV sets out exposure data for three standard scenarios:

 Residential areas where vegetables are grown and consumed;

 Allotments;

 Commercial and industrial areas.

In addition the CLEA SGV calculated their SGV assuming a sandy loam soil with 6% Soil Organic Matter. For each of the substances the Environment Agency have made a number of substance specific decisions in their assessment.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx

GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

SKM Enviros Generic Assessment Criteria Approach for contaminants where SGVs have been published

SKM Enviros has adopted the SGVs where they have been published and as each SGV is produced by the Environment Agency they will replace the current interim GAC values. However the standard scenarios did not include residential areas where no plants are grown. This is a common land use and one often used in screening for public open spaces. In addition they are not conservative for soil where the organic matter is less than 6% (where volatilisation and uptake by plants may be higher). Therefore, SKM Enviros has developed a set of internal generic assessment criteria (GACs) for all contaminants where the EA issued an SGV report or toxicological data to allow initial assessment of data for standard scenarios and to cover a wider range of scenarios including residential areas where no plants are grown.

Approach for contaminants where no SGV has been published

The current range of published SGVs is limited. In order to expand the range of GACs, SKM Enviros have reviewed toxicological and physicochemical data from a number of sources. This has included:

 Information in the TOX report which have not been revised;

 Information from a report by LQM/CIEH (Ref 9) revised in 2009 to assess contaminant not due to be assessed by the Environment Agency

 Information from the CLAIRE/CIEH initiative to (Reference 16);

 Information on physical and chemical properties of various organics provided in and Environment Agency report SR7.

The CLEA model outputs do not include the data justification, if this is required SKM Enviros are happy to provide the CLEA model, which includes the chemical database and justifications, on CD for review.

Approach for lead

For lead, the Environment Agency originally used a different approach to that set out in the CLEA model. The model used for lead was based on empirical curves associated with blood lead levels. The Environment Agency in their FAQs has indicated they may revert to using the CLEA model but have not indicated how the toxicological data will be assessment. In the interim SKM Enviros have continued to use the CLEA SGV for lead published pre 2008.

Sources used for physic-chemical parameters

Where available, physico-chemical parameters for metals have been taken from former SGV reports, and parameters for organic chemicals have been taken from Environment Agency Report SR7. For all other contaminants a literature search for suitable data has been undertaken in line with the approach set out in line with the approach set out in SR2. References for all input parameters are in the CLEA model but do not appear on the CLEA output sheets. We are happy to provide an electronic copy of the CLEA model with this data is required.

For the hydrocarbons, the threshold risk has been considered using the approach devised by the TPH criteria working group (TPH CWG) (Ref 12) where the total petroleum hydrocarbons are divided into fractions based on their mobility and toxicity. As part of the work in deriving appropriate fractions, characteristic physicochemical data has been derived for these fractions and this has been used to calculate GACs.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx

GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

Henry’s Law Constants are generally measured or reported at 25oC whereas the soil temperature is generally assumed to be 10oC in the UK. As the temperature falls, the Henry’s Law Constant falls. The changes can be estimated using the Clausius-Clapeyron equation which is described by the USEPA (Ref 12) and referenced by SR7. In order to implement these changes knowledge of the boiling point, critical temperature, and enthalpy of vaporisation is required.

When sufficient information is available, adjustments have been made to Henry’s Law Constant in line with SR7. For contaminants in the report these calculations are already provided in the associated database. For TPH fractions the data have been derived from the TPH CWG tables, and the enthalpy of vaporisation calculated according to the method described by the USEPA (Reference 13). For all other substances no adjustment has been made and the Henry’s Law Constant is slightly conservative.

Sources used for toxicological input data

The majority of contaminants being assessed are those for which toxicological data has been published by the Environment Agency. To expand the list of contaminants we have also use:

 Information in the former TOX reports which have not been revised;

 Information from a report by LQM/CIEH (Ref 9) revised in 2009 to assess contaminant not due to be assessed by the Environment Agency.

For the assessment of hydrocarbons a two stage approach is employed. The non-threshold risk is assessed by an assessment of known carcinogenic indicators. These include benzene, and seven PAHs with non-threshold effects (benzo(a)pyrene, chrysene, benz[a]athracene, benzo[b]fluoranthere, benzo[k]fluoranthere, dibenz[ah]anthracene, indeno[1,2,3 c,d]pyrene) identified by the Environment Agency (Ref 3). The relative carcinogenicity of the PAHs has been based on that of benzo(a)pyrene.

The threshold risk is then assessed in accordance with the TPH criteria working group fractions and methodology which is described below in Section 6. The threshold risk from benzene has been assessed by assessing benzene concentrations against a value derived using the toxic risk from toluene, and the non-threshold risk from benzene has been assessed in line with the TOX and SGV reports.

The sources for each of the substances assessed (except hydrocarbons) are included in Annex 1.

Assessment Approach for Hydrocarbons

Thresholds for individual hydrocarbon fractions in the TPH CWG analysis have been calculated using the CLEA model with toxicological and physicochemical data for the individual fractions derived from the TPH Criteria Working Group Documents (Ref 12).

Comparing individual fractions against these thresholds may not be sufficiently conservative. This is because a number of the hydrocarbons have similar toxic effects on the liver. The approach in SR2 is that additivity should be considered for contaminants where substances may act on the same target organ system. The critical effect for the aliphatic fractions is hepatoxicity (toxicity to the liver). Thresholds for the majority aromatic fractions are not based on this effect, however other studies (such as those detailed in the TOX report for naphthalene) indicate that aromatic fractions may also affect the liver. Therefore, combined (or “additive”) exposure close to the threshold for two separate fractions could lead to a total unacceptable exposure from hydrocarbons.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx

GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

Therefore, the petroleum fractions are assumed to be additive and a spreadsheet has been set up to carry out a simple additivity calculation i.e. does not allow for synergistic or antagonistic effects. To assess this we have used the approach set out in the Environment Agency guidance “The UK Approach for Evaluating the Human Health Risks from Petroleum Hydrocarbons in Soils” to examine the effect of additivity. This involves calculating the hazard Index using the equation set out below) for each sample and determining if this is greater of less than 1.

Actual _ concentration _ in _ soil Hazard _ Index   Eachhydrcarbon Screening _ value _ in _ soil Fraction As the concept of the Hazard Index can be quite difficult to communicate, SKM Enviros has also gone a stage further - by dividing the total concentration in the sample by the Hazard Index we have converted this back into a mixture specific threshold for each sample in mg/kg or g/kg as appropriate. By employing this approach we have addressed the additive risk from Total Petroleum Hydrocarbons.

For hydrocarbons a sub-soil to indoor air correction factor of 10 has been applied to account for over-estimation of hydrocarbon vapour transport into buildings using the Johnson & Ettinger model, this is in line with the approach adopted in the SGV reports for BTEX compounds. It is noted in the SGV report for toluene that:

“The reasons for the difference between empirical and theoretical calculations is the subject of continued debate (CIRIA, in press), reported factors include sampling technique, biodegradation in the vapour phase, and natural ground heterogeneity. As soil vapour is transported upwards towards the building, biodegradation of petroleum hydrocarbons commonly occurs which can significantly affect the amount of vapour that will enter the building. Among other factors, this is dependent on the oxygen availability in the unsaturated zone)”.

This adjustment approach is also used in the LQM/CIEH report (Reference 9).

Where EPH analysis with risk banding has been undertaken the sum of the aliphatic and aromatic hydrocarbons in each fraction is reported. In this instance we have assumed the worst case, which is that all of the hydrocarbons in each band are the more toxic aromatic fraction, and thus produce conservative mixture specific thresholds.

In all assessments the additivity calculation assumes that non-detects are actual concentrations. Where no data is available for a band then zero is entered.

Background Exposure for Hydrocarbons

In accordance with the SR2 when considering threshold substances it is important to consider the background exposure to these substances and reduce the TDI accordingly to give a tolerable daily soil intake (TDSI). SR2 states that where there is no background data the exposure should be consider as zero.

For hydrocarbons the situation is complicated. CIEH/LQM have assumed the intake of TPH in food and air is very high. Thus in accordance with the SR2 guidance on where the background is known to be a high proportion of the TDI (50% or greater), TDSI has been reduced to 50% of the TDI. We believe the approach taken by LQM and CIEH is overly conservative.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx

GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

The composition of the mixture is paramount. There is data from the Food Standards Agency looking at addition of C10-C40 food grade mineral oils to food. The amount of these substances present in food is very high and daily intakes of up to 14.28mg/day and 61.25mg/day have been noted in the UK and US, respectively. It is however noted that the Acceptable Daily Intakes for these food grade hydrocarbon mixtures are much higher than the tolerable daily intakes produced by the TPH criteria Working Group who were considering fuels. It is thus not appropriate to cite a mean daily intake based on food grade hydrocarbons as background exposure to fuel based hydrocarbons.

We note that recent reviews of hydrocarbon exposure in Canada quote:

“Excluding PAH, no reports of generalized background contamination of air, water, food or soil (unrelated to contaminated sites) were located for component PHC [petroleum hydrocarbons] in fractions 2, 3 and 4 (i.e., C>10). This likely stems from their generally low or negligible solubility and volatility. PAH are evaluated separately from PHC for purposes of risk assessment of contaminated sites and, therefore, they are not considered within the various PHC fractions being evaluated here.

Due to the lack of evidence for, and low probability of, ubiquitous environmental contamination with PHC in fractions 2, 3 and 4, the estimated daily intakes (EDI) of PHC in fractions 2, 3 and 4 from background sources are considered to be zero. PHC in fraction 1 (C6 to C10) are relatively volatile and soluble.

As a result, aliphatic and aromatic compounds in this carbon range have been reported in drinking water, outdoor air, ambient air and some foods.“ (Reference 14).

For PAHs the first edition of the Air Quality Guidelines for Europe (Reference 15) considered the total concentration of 22 PAHs in a busy street as having a total concentration of 90.26ng/m3 in an urban street equating to 1.6g/day of these PAHs. This is much lower than the value of 420g/day representing 10% of the TDI inhalation used. Even scaling this up to represent the 500 PAH detected in air in first edition of the Air Quality Guidelines for Europe (and assuming that there other PAHS are in a similar proportion which is unlikely), the total exposure will be very low compared to the TDI.

It is therefore considered that the assumptions used by LQM/CIEH that at least 50% of the TDI derives from diet is overly conservative.

We have adopted the same approach as described for Canada and have adopted the Estimated Daily Intakes via all pathways estimated by CCME for specific fractions (with the exception of benzene and toluene where the UK data has been used). We would anticipate that the concentrations of hydrocarbons in air will decrease with decreasing volatility. For inhalation exposure we have used the total daily intake produced by Mole Valley and cited by LQM/CIEH (Reference 9).

The MDIs adopted by SKM Enviros are tabulated below. We have also included for comparison the MDI representing 10% of the TDI (and hence making 10% difference to the tolerable exposure by oral or inhalation routes). This is useful in that it demonstrates the high background exposure required to make a 10% difference to the tolerable daily intakes from soil due to hydrocarbons.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx

GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

Ingestion Inhalation dose Inhalation Oral Dose exposure representing exposure representing Reference for Reference for Fraction adopted by 10% of TDI adopted by 10% of TDI adopted value inhalation dose SKM inhalation SKM oral (μg/day) (μg/day) (μg/day)1 (μg/day) Aliphatic C5-6 17500 3180 CCME 184000 380 Mole Valley cited by January 2008 LQM/CIEH Aliphatic C6-8 35000 1630 CCME 36800 144 Mole Valley cited by January 2008 LQM/CIEH Aliphatic C8-10 700 721 CCME 2030 104 Mole Valley cited by January 2008 LQM/CIEH Aliphatic C10- 700 0 CCME 2030 55.4 Mole Valley cited by 12 January 2008 LQM/CIEH Aliphatic C12- 700 0 CCME 2030 12.2 Mole Valley cited by 16 January 2008 LQM/CIEH Aliphatic C16- 14000 0 CCME N/A NR Mole Valley cited by 21 January 2008 LQM/CIEH Aliphatic C21- 14000 0 CCME N/A NR Mole Valley cited by 35 January 2008 LQM/CIEH Aromatic C6-7 N/A 10 Environment Agency, N/A 3 Environment Agency, (benzene) Contaminants in soil: Contaminants in soil: updated collation of updated collation of toxicological data and toxicological data and intake values for intake values for humans -Benzene, humans -Benzene, Science report: Science report: SC050021/SR SC050021/SR TOX11, TOX11, March March 2009 Aromatic C7-8 N/A 10 Environment Agency, N/A 520 Environment Agency, (toluene) Contaminants in soil: Contaminants in soil: updated collation of updated collation of toxicological data and toxicological data and intake values for intake values for humans -Toluene, humans -Toluene, Science report: Science report: SC050021/SR SC050021/SR TOX14, TOX14, March March 2009 Aromatic C8-10 280 657 CCME 420 353 Mole Valley cited by January 2008 LQM/CIEH Aromatic C10- 280 0 CCME 420 304 Mole Valley cited by 12 January 2008 LQM/CIEH Aromatic C12- 280 0 CCME 420 0.96 Mole Valley cited by 16 January 2008 LQM/CIEH Aromatic C16- 210 0 CCME N/A 0.89 Mole Valley cited by 21 January 2008 LQM/CIEH Aromatic C21- 210 0 CCME N/A 0.19 Mole Valley cited by 35 January 2008 LQM/CIEH

CCME 2008 ‐Canada‐Wide Standard for Petroleum Hydrocarbons (PHC) in Soil: Scientific Rationale Supporting Technical Document, January 2008 Notes: 1 = provided for comparative purposes only

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx

GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

Review of CLEA Methodology

In adopting the CLEA model it is important to consider the standard use and confirm the assumption made. These assumptions are considered below.

Exposure Parameters

All exposure parameters applied to the GACs are the default values set out in SR3, which are for the standard CLEA critical receptors as follows:

 0-6 year old female child living at home (residential land uses);

 0-6 year old female child visiting allotments with parent (allotments land use);

 16-65 year old female adult (commercial and industrial use).

In addition for cadmium consideration has been given to lifetime exposure for the residential and allotment setting in line with the revised SGV report on cadmium.

Exposure Pathways

The following table shows the pathways that have been considered under each of the scenarios considered.

Direct Ingestion of Inhalation Inhalation ingestion home grown of vapour Inhalation Inhalation of vapour Dermal Pathway of soil and vegetables intruding of dust of dust in outdoor uptake indoor and attached into indoors outdoors areas dust soils buildings Residential       with vegetable  consumption Residential without       x vegetable consumption Residential without vegetable      x x consumption or indoor air inhalation Allotments     x x 

Commercial/       x industrial

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx

GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

Soil Parameters

The GACs have been based on a sandy loam soil which is the default soil type for use when calculating SGVs as described in SR3. This is the most conservative soil type commonly encountered in UK soils. If site soils are sands or gravels with no fines content then further assessment should be undertaken for volatile compounds.

For volatile contaminants the soil air permeability is highest for sand. For non-volatile contaminants or pathways where inhalation of vapour is not considered the soil type has very little effect on the exposure.

The fraction of organic content has a significant effect on the partitioning of organic contaminants. Thus less contaminant is in the vapour form or available for plant uptake in soil with higher organic content. The GACs have thus been calculated for a series of soil organic contents; 1%, 2.5% and 6%. The 6% value is the default soil organic matter content to be used in calculation of SGVs (Ref 10), the 1% and 2.5% values are taken from the former SGV reports for organic contaminants as being representative of concentrations typically encountered in UK soils. Therefore, the choice of GAC to use depends on the organic carbon content of the soil on the site. The only pathways that are significantly affected by soil organic matter content are vapour inhalation and plant uptake by organic compounds and methylmercury.

Pathways Considered for the GACs

Direct soil ingestion and ingestion of indoor dust

The ingestion rate, exposure frequency and all other parameters relating to soil ingestion have been set to the default parameters in the CLEA model.

Vegetable Consumption

All vegetable consumption rates, exposure frequencies and durations are set to the default values in the CLEA model. The allotments calculation assumes a moderate rather than high-end consumer.

For heavy metals, SKM Enviros has applied the soil to plant uptake factors published in the former SGV reports, where available and for other metals the values derived by Baes et al have been applied (Reference 11). The pH as entered into the CLEA model in Basic Settings has been set to pH 7 for all assessments. However, where there are literature data for plant uptake factors at different pH levels, these factors have been applied to the model and the contaminant labelled accordingly e.g. Cadmium pH 6-8. For mercury, where plant uptake is affected by soil organic matter content, plant uptake factors for each default organic content have been applied.

For all other contaminants the default vegetable uptake models in CLEA have been used to predict plant uptake.

Inhalation of indoor vapours and dust

All assumptions for the indoor vapour inhalation model are the same as the default parameters set out in SR3. The building types applied are ‘small house’ and ‘pre-1970s office’.

The indoor dust inhalation pathway assumes that 50% of indoor dust is derived from soil (the soil to dust transport factor). We understand that contaminant-specific transport factors are to be published by the Environment Agency, however until these are released the baseline assumption from SR3 of 50% has been applied. SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx

GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

Saturation

The CLEA model includes a default calculation to check whether the calculated safe levels of organic contaminants exceed the concentration at which either the water solubility limit or maximum vapour concentration has been exceeded. This is indicated by a traffic light system of amber, red, and green. Where theoretical saturation limits are exceeded further assessment may show that a higher soil concentration is safe for future users, but this has not been undertaken for GACs. Where an SGV has been published that is based upon the predicted saturation limit SKM Enviros have adopted the saturation limit approach and adjusted the corresponding GACs at lower organic contents or non-standard land uses.

For the remaining substances (particularly the hydrocarbons in a commercial/industrial end use) no adjustment has been made to reduce the threshold to saturation. This is in part as saturation of hydrocarbon mixture is complex and should be assessed on a mixture specific basis. Furthermore, where saturation occurs it implies that the vapour pathway lead to exceedance of the acceptable dose principally via inhalation and thus by not allowing for saturation the oral and dermal exposure pathways are considered but in a conservative fashion. Where site observations report that free- phase organics are present, as opposed to modelling predicting that it may be present, then more detailed consideration of risks is undertaken.

Dermal uptake

All parameters for dermal uptake have been set to the default parameters in the CLEA model. Dermal uptake factors applied are the default values from SR3. For metals where no literature value is available, dermal uptake factors have been set to zero as advised in SR3. For contaminants such as phenol, which can have a corrosive effect upon dermal contact, consideration has also been given to acute dermal effects.

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx

GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

References

1) DEFRA and Environment Agency (2009) The Contaminated Land Exposure Assessment (CLEA) Model: Technical Basis and Algorithms, Report CLR10. Withdrawn August 2008. 2) DEFRA and Environment Agency (2002c) Toxicological Reports for Individual Soil Contaminants, Report CLR9 TOX reports. 3) Environment Agency. The UK Approach for Evaluating Human Health Risks from Hydrocarbons in Soils. P5-080/TR3. February 2005. 4) Environment Agency. Updated Technical Background to the CLEA Model. SC050021/SR3. January 2009. 5) Environment Agency. Human Health Toxicological Assessment of Contaminants in Soil. SC050021/SR2. January 2009. 6) Environment Agency. Compilation of Data for Priority Organic Pollutants for Derivation of Soil Guideline Values. SC050021/SR7. November 2008. 7) DEFRA and Environment Agency (2002e) Soil Guideline Values Report for Individual Soil Contaminants, Report CLR10 SGV1-10. Withdrawn August 2008. 8) Environment Agency Website. CLEA FAQs. http://www.environment- agency.gov.uk/research/planning/33718.aspx Accessed 29th January 2009. 9) Nathaniel C.P., McCaffrey C., Ashmore M.H., Cheng Y.Y., Gillett A., Ogden r. & Scott D. The LQM/CIEH Generic Assessment Criteria for Human Health Risk Assessment (2nd Edition). 2009 10) Environment Agency. Changes we have made to the CLEA framework documents. January 2009. 11) Oak Ridge National Laboratory. A Review and Analysis of parameters for Assessing Transport of Environmentally Released Radionuclides through Agriculture. ORNL-5786. 12) Total Petroleum Hydrocarbon Criteria Working Group Series, Volumes 1-5 1997 to 1999. http://www.aehs.com/publications/catalog/contents/tph.htm 13) USEPA. FACTSHEET: Correcting the Henry’s Law constant for Soil Temperature. June 2001. 14) CCME. CCME 2009 Supporting Technical Document January 2008. 15) WHO document Air Quality Guidelines for Europe Edition 1 2000 http://www.euro.who.int/document/aiq/5_9pah.pdf. 16) CLAIRE The Soil Generic Assessment Criteria for Human Health Risk Assessment, December 2009

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx

GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

MODEL OUTPUT SHEETS ARE AVAILABLE ON REQUEST

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx

GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

ANNEX 1

SOURCES OF TOXICOLOGICAL DATA

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx

GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

Oral Inhalation Reference Reference Determinand Type dose Source Type dose Source

g/kgbw/day g/kgbw/day Chlorinated Solvents Environment Agency Environment Agency Tetrachloroethene TDI 14 R&D Publication TOX TDI 71 R&D Publication TOX 23 April 2003 23 April 2003 Environment Agency Environment Agency Trichloroethene ID 5.2 R&D Publication TOX ID 5.2 R&D Publication TOX 24 October 2004 24 October 2004 Environment Agency Environment Agency Vinyl Chloride ID 0.014 R&D Publication TOX ID 0.3 R&D Publication TOX 18 April 2003 18 April 2003 Environment Agency Environment Agency 1,2 Dichloroethane ID 0.12 R&D Publication TOX ID 0.12 R&D Publication TOX 22 August 2004 22 August 2004 Environment Agency Environment Agency 1,1,1 Trichloroethane TDI 600 R&D Publication TOX TDI 600 R&D Publication TOX 25 April 2003 25 April 2003 Environment Agency Environment Agency 1,1,2,2 Tetrachloroethane TDI 5.8 R&D Publication TOX TDI 5.8 R&D Publication TOX 16 April 2003 16 April 2003 Environment Agency Environment Agency 1,1,1,2 Tetrachloroethane TDI 5.8 R&D Publication TOX TDI 5.8 R&D Publication TOX 16 April 2003 16 April 2003 Environment Agency Environment Agency Carbon Tetrachloride TDI 1.42 TDI 3.26 TOX 21 April 2005 TOX 21 April 2005 LQM/CIEH Generic LQM/CIEH Generic Assessment Criteria for Assessment Criteria for Trichloromethane TDI 13.7 Human Health Risk TDI 40 Human Health Risk Assessment 2nd Assessment 2nd Edition, 2009 Edition, 2009 Polycyclic Aromatic Hydrocarbons Environment Agency Environment Agency Benzo(a)pyrene ID 0.02 R&D Publication TOX 2 ID 0.00007 R&D Publication TOX 2 April 2002 April 2002 Based on ten times the Based on ten times the index dose for index dose for benzo(a)pyrene benzo(a)pyrene Benzo(b)fluoranthene ID 0.2 ID 0.0007 (Environment Agency (Environment Agency R&D Publication TOX 2 R&D Publication TOX 2 April 2002) April 2002) Based on ten times the Based on ten times the index dose for index dose for benzo(a)pyrene benzo(a)pyrene Benzo(k)fluoranthene ID 0.2 ID 0.0007 (Environment Agency (Environment Agency R&D Publication TOX 2 R&D Publication TOX 2 April 2002) April 2002)

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx

GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

Oral Inhalation Determinand Type Reference Source Type Reference Source dose dose Based on ten times the Based on ten times the index dose for index dose for benzo(a)pyrene benzo(a)pyrene Chrysene ID 0.2 ID 0.0007 (Environment Agency (Environment Agency R&D Publication TOX 2 R&D Publication TOX 2 April 2002) April 2002) Based on ten times the Based on ten times the index dose for index dose for benzo(a)pyrene benzo(a)pyrene Dibenz(ah)anthracene ID 0.02 ID 0.00007 (Environment Agency (Environment Agency R&D Publication TOX 2 R&D Publication TOX 2 April 2002) April 2002) Based on ten times the Based on ten times the index dose for index dose for benzo(a)pyrene benzo(a)pyrene Indeno(1,2,3,cd)pyrene ID 0.2 ID 0.0007 (Environment Agency (Environment Agency R&D Publication TOX 2 R&D Publication TOX 2 April 2002) April 2002) Environment Agency Environment Agency Naphthalene TDI 20 R&D Publication TOX TDI 0.86 R&D Publication TOX 20 December 2003 20 December 2003 Based on ten times the Based on ten times the index dose for index dose for benzo(a)pyrene benzo(a)pyrene Benzo(a)anthracene ID 0.2 ID 0.0007 (Environment Agency (Environment Agency R&D Publication TOX 2 R&D Publication TOX 2 April 2002) April 2002) Miscellaneous Organics LQM/CIEH Generic LQM/CIEH Generic Assessment Criteria for Assessment Criteria for Carbon disulphide TDI 100 Human Health Risk TDI 28.6 Human Health Risk Assessment 2nd Assessment 2nd Edition, 2009 Edition, 2009 LQM/CIEH Generic LQM/CIEH Generic Assessment Criteria for Assessment Criteria for Hexachloro-1,3-butadiene TDI 0.2 Human Health Risk TDI 0.2 Human Health Risk Assessment 2nd Assessment 2nd Edition, 2009 Edition, 2009 Metals and inorganics LQM/CIEH Generic LQM/CIEH Generic Assessment Criteria for Assessment Criteria for Beryllium TDI 2 Human Health Risk ID 0.0012 Human Health Risk Assessment 2nd Assessment 2nd Edition, 2009 Edition, 2009 LQM/CIEH Generic LQM/CIEH Generic Assessment Criteria for Assessment Criteria for Boron TDI 160 Human Health Risk TDI 2.9 Human Health Risk Assessment 2nd Assessment 2nd Edition, 2009 Edition, 2009

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx

GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

Oral Inhalation Determinand Type Reference Source Type Reference Source dose dose LQM/CIEH Generic LQM/CIEH Generic Assessment Criteria for Assessment Criteria for Human Health Risk Human Health Risk Assessment 2nd Chromium III TDI 150 TDI 0.1 Assessment 2nd Edition, 2009. Based Edition, 2009. Not on FSA NOAEL from commented on in 2003 not available for TOX4 the TOX4 report TOX4 inhalation dose for chromium based on Chromium VI derived LQM/CIEH Generic from the WHO 2000 Assessment Criteria for report. (Note this is the Human Health Risk same report used by Assessment 2nd LQM/CIEH although Chromium VI TDI 1 Edition, 2009. Based ID 0.001 LQM/CIEH used a on More recent data different basis for the from USEPA in 2008 dose derived and do not available for the not cite the TOX4 TOX 4 report report in this context although it is not yet withdrawn.) LQM/CIEH Generic LQM/CIEH Generic Assessment Criteria for Assessment Criteria for Copper TDI 160 Human Health Risk TDI 0.286 Human Health Risk Assessment 2nd Assessment 2nd Edition, 2009 Edition, 2009 LQM/CIEH Generic LQM/CIEH Generic Assessment Criteria for Assessment Criteria for Vanadium TDI 3 Human Health Risk TDI 0.0286 Human Health Risk Assessment 2nd Assessment 2nd Edition, 2009 Edition, 2009 LQM/CIEH Generic LQM/CIEH Generic Assessment Criteria for Assessment Criteria for Zinc TDI 600 Human Health Risk TDI 600 Human Health Risk Assessment 2nd Assessment 2nd Edition, 2009 Edition, 2009

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx

GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

Appendix G Soil Chemistry Data

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx

GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

Appendix H Certificate of Analysis – Soil

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx

GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

Appendix I TPH Calculation Sheets

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx

GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

Appendix J Water Chemistry Data

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx

GPSS Portfolio – Backford South Phase One And Two Land Quality Assessment – Final

Appendix K Certificate of Analysis - Waters

SKM Enviros

I:\JLWM\Projects\JL30611\Deliverables\Reports\Individual Sites\Backford South\Final Report\Backford South Phase 1 & 2 LQA FINAL.docx