Ground Contamination Risk Assessment Report€¦ · Ground Contamination Risk Assessment Report for Balfour Beatty NOVEMBER 2009 Project No.: 5311 Ramboll UK Ltd. The Capital Building,

ST. AMBROSE

Ground Contamination Risk Assessment

Report

for

Balfour Beatty

NOVEMBER 2009

Project No.: 5311

Ramboll UK Ltd.The Capital Building,

12/13 St. Andrew Square,Edinburgh. EH2 2AF

tel 0131 550 4070fax 0131 550 4093

[email protected]

Ground Contamination Risk

Assessment Report

ST. AMBROSE

Balfour Beatty

Revision History

Rev Date Purpose/Status Document Ref. Comments

1A 26th November 09 Final 5311.E.GQRA.1A For Issue

Author: Checked by: Approved by:

Environmental Engineer Senior Environmental Consultant Director

St. Ambrose Ground Contamination Risk Assessment Report

5311.E.GQRA.1A Executive Summary

EXECUTIVE SUMMARY SCOPE

Purpose of the report

Ramboll UK Ltd (RUK) was instructed by Balfour Beatty to design a supplementary site investigation and provide an interpretative ground contamination assessment at the proposed St. Ambrose School site in Coatbridge.

The proposed development will comprise the construction of St. Ambrose High School including a two-storey school building with associated school pitches, car parking, play areas and soft landscaping.

SITE INFORMATION

Grid Reference 271546, 665970 Site Area (approx.) 13.5ha

Current Site Description

Currently the site is occupied by numerous sports pitches to the south of Townhead Road and is in use by the general public as a recreational area. An area of car parking and an access road is present in the northeast of the site.

History

Until the 1980s, the site was used as rough pasture in a mining area with a railway crossing the north of the site and the eastern site boundary and coal pits to the northeast and southeast of the site. During the 1980s, the railway in the north was dismantled and a mineral railway was constructed across the southern area of the site.

The site was then used as a landfill from 1945-1972. By the 1990s the site was in use as playing fields following reprofiled and has remained so up to the present day. No further details are available regarding the capping of the landfill and development of the playing fields.

SITE INVESTIGATION

Previous SI A preliminary and main intrusive investigation were undertaken on site by URS in 2006 and 2008 respectively.

Activities

The supplementary site investigation works designed by Ramboll to address data gaps comprised 11No. mechanically-excavated trial pits to a maximum depth of 4.10mbgl, 11No. hand-excavated pits to a maximum depth of 1.20mbgl and soil sampling for chemical analysis.

Laboratory Analysis

37No. soil samples (including one duplicate) and 8No. leachate samples were analysed for a typical chemical suite including: pH, selected metals and inorganics, extractable petroleum hydrocarbons (EPH), polycyclic aromatic hydrocarbons (PAHs), phenols and an asbestos screen. Specific samples were also scheduled for foc, speciated hydrocarbons, volatile organic compounds and semi-volatile organic compounds.

GROUND CONDITIONS

Geology

Made Ground was encountered across the site comprising topsoil, reworked topsoil material and probable landfill material. The Made Ground ranges in thickness between 0.30m and 6.00m. The greatest depths of Made Ground were typically reported in the northern area of the site.

Superficial deposits of peat and glacial deposits of clay, sand and silt were encountered underlying Made Ground strata.

The solid geology of the Middle Coal Measures, described as interbedded sandstone, mudstone and coal was encountered at depths of between 6.50-23.20mbgl and was recovered as highly weathered sandstone.

Hydrology & Hydrogeology

Groundwater was typically recorded at the superficial to solid interface at depths ranging from 12.80 to 23.20mbgl. It is understood that this is the underlying aquifer. Perched shallow groundwater was also reported across the site within the Made Ground and superficial deposits, although typically, perched groundwater was reported above the peat at depths ranging from 1.90 to 4.70mbgl.

There are various drains labelled on the site plan located southwest of the site with Drumpellier Country Park, the nearest being approximately 10m from the southwest site boundary. On investigation, these are surface ditches, typically dry, which are likely to fill with water during heavy rain. The nearest surface water receptor is therefore Monkland Canal, which runs east to west and lies approximately 350m south of the site and Lochend Loch and Woodend Loch lie approximately 450m west and 650m northwest of the site boundary respectively.



GROUND CONTAMINATION

Human Health

The risks to Human Health via direct contact with lead and nickel in localised areas across the site are considered to be LOW / MODERATE as these materials are at depths proposed to be excavated as part of the cut and fill works.

Localised elevated concentrations of PAHs are located in areas of proposed fill where there will be at least 600mm of fill and existing material located above the source strata. Therefore, these localised impacts are unlikely to present a significant risk via direct contact pathways. Risks to Human Health from these impacts are therefore considered to be LOW.

Risks to human health caused by elevated benzo(a)pyrene in probable landfill and topsoil material across the site and elevated benzo(a)anthracene in topsoil are considered likely to be significant in areas of soft landscaping where there may be an active direct contact pathway. Therefore, the risk to human health from benzo(a)pyrene and benzo(a)anthracene in soft landscaped areas is classified as MODERATE.

Controlled Waters

Risks to the Secondary Aquifer underlying the site are classified as LOW / MODERATE due to the impacts of manganese, ammonia and PAH reported within the shallow groundwater. Risks to the underlying aquifer from the localised hydrocarbons and marginal impacts of copper and zinc within the shallow groundwater are classified as LOW. Due to the significant depths of impermeable deposits including peat and clay overlying the aquifer in the majority of locations across the site it is considered unlikely that significant vertical migration of contaminants will occur.

In areas of the proposed soakaways the risks to the underlying aquifer are considered to be LOW / MODERATE.

The development proposals include increasing the area of hardstanding across the site thus reducing leaching potential and likely pathways through the landfill material. Based on the significant distance to the nearest surface water receptor (Monkland Canal; Lochend and Woodend Lochs all >350m from the site) and the proposed development minimising pollutant linkages, the risks to the surface water receptors are considered to be LOW.

Ground Gas

Ground gas monitoring visits were undertaken by URS in 2006 and 2008/9. The concentrations reported would classify the proposed development as Characteristic Situation 4 and appropriate ground gas protections measures will be required in the proposed development in accordance with CIRIA 665 (2007) and BS8485 (2008).

RECOMMENDATIONS

Further Assessment

• A Human Health Detailed Quantitative Risk Assessment (DQRA) is recommended in order to further assess the potential risks caused by site-wide impacts of benzo(a)anthracene in topsoil and benzo(a)pyrene in topsoil and landfill material.

Remedial Measures Required

• Ground gas protection measures will be required in the proposed development in accordance with Characteristic Situation 4 (CIRIA C665). A design for these protection measures has been proposed.

• Hotspots of lead and nickel have been identified in areas proposed to be excavated as part of the cut and fill works. During enabling works it is recommended that this material is stockpiled separately and subjected to validation testing to establish whether the material is suitable for use.

Additional Considerations

It is recommended that a suitably qualified Environmental Consultant is on site during the enabling works to ensure that should any areas of apparent contamination be exposed; the material is excavated, stockpiled separately onsite and subjected to validation testing in order to ensure the material is suitable for use. Allowances are also recommended to be made for the removal, treatment and disposal of shallow groundwater should dewatering be required during excavation.

An Environmental Specification Report is recommended to ensure the Contractor is undertaking all enabling works in accordance with the recommendations made in this report. A Validation Report will also be required to demonstrate that the enabling works have been carried out according to the Environmental Specification.

Laying underground services in potentially contaminated Made Ground materials has the potential to establish preferential flow pathways and therefore materials should be used appropriate to the level of contamination identified on site, particularly with regard to underground mains water supply. Consultation with Scottish Water is advised.

The site has been historically redeveloped and used as a landfill, and although not encountered during the site investigations, localised deposits of asbestos-containing materials have the potential to be present in Made Ground across the site. Appropriate health and safety precautions (i.e., provision of appropriate PPE to site development workers, etc.) should be adopted during enabling works.


5311.E.GQRA.1A Contents

CONTENTS

EXECUTIVE SUMMARY 1

CONTENTS 1

1 INTRODUCTION 3

1.1 BRIEF 3 1.2 BACKGROUND 3 1.3 OBJECTIVES 3 1.4 CONSTRAINTS AND LIMITATIONS 4

2 SITE SETTING 5

2.1 SITE DESCRIPTION 5 2.2 SITE HISTORY 5 2.3 GEOLOGY 5 2.4 HYDROGEOLOGY & HYDROLOGY 6 2.5 FLOOD RISK 6 2.6 GROUND GAS 6 2.7 PREVIOUS GROUND INVESTIGATIONS 7 2.8 PRELIMINARY CONCEPTUAL MODEL 7

3 SITE INVESTIGATION 10

3.1 DESIGN 10 3.2 SITE INVESTIGATION ACTIVITIES 10 3.3 LIMITATIONS 10 3.4 LABORATORY CHEMICAL ANALYSIS 11

4 GROUND CONDITIONS 13

4.1 GENERAL STRATIGRAPHY 13 4.2 VISUAL AND OLFACTORY OBSERVATIONS OF POTENTIAL CONTAMINATION 14 4.3 GROUNDWATER OCCURRENCE 15

5 GROUND CONTAMINATION ASSESSMENT 16

5.1 HUMAN HEALTH ASSESSMENT 16 5.2 CONTROLLED WATERS ASSESSMENT 20 5.3 GROUND GAS RISK ASSESSMENT 28

6 GROUND CONTAMINATION 31

6.1 CONCEPTUAL SITE MODEL 31 6.2 QUALITATIVE RISK ASSESSMENT 33 6.3 DEVELOPMENT CONSIDERATIONS 36

7 RISK MANAGEMENT STRATEGY 38

7.1 SIGNIFICANT POLLUTANT LINKAGES 38 7.2 RECOMMENDATIONS 38 7.3 ADDITIONAL CONSIDERATIONS FOR DEVELOPMENT 39

8 REFERENCES 41



APPENDICES

APPENDIX A DRAWINGS AND FIGURES

DRAWING 5311/E/001 EXPLORATORY HOLE LOCATION PLAN

DRAWING 5311/E/002 PROPOSED DEVELOPMENT PLAN (SITE LAYOUT)

DRAWING 5311/E/003 CURRENT SITE LAYOUT PLAN (EXISTING SITE LEVELS)

DRAWING 5311/E/004 CONCEPTUAL SITE MODEL (CROSS SECTION)

FIGURE 2.1 SITE LOCATION PLAN

FIGURE 2.2 PHOTOGRAPHS OF DRAINS ADJACENT TO SITE

APPENDIX B CORRESPONDENCE WITH NORTH LANARKSHIRE COUNCIL / WSP

APPENDIX C GROUND CONTAMINATION ASSESSMENT; CONTEXT AND METHODOLOGIES

APPENDIX D EXPLORATORY HOLE LOGS FROM SUPPLEMENTARY SITE INVESTIGATION (RUK)

APPENDIX E CHEMICAL LABORATORY RESULTS FROM SUPPLEMENTARY SITE INVESTIGATION (RUK)

APPENDIX F EXPLORATORY HOLE LOGS AND CHEMICAL ANALYSIS FROM PREVIOUS INVESTIGATION (URS, 2006)

APPENDIX G EXPLORATORY HOLE LOGS AND CHEMICAL ANALYSIS FROM PREVIOUS INVESTIGATION (URS, 2008)

APPENDIX H CHEMICAL SCREENING TABLES

APPENDIX I CORRESPONDENCE TO COUNCIL FROM URS REGARDING GROUND GAS (MAY 2009)

APPENDIX J GROUND GAS MONITORING RESULTS (URS 2006; 2008/9)

APPENDIX K GROUND GAS PROTECTION SYSTEM PROPOSAL (LANDLINE)


5311.E.GQRA.1A Page 3

1 INTRODUCTION

1.1 Brief


This report provides a factual summary of the supplementary investigation and an assessment of ground contamination risks based on all available data.

The proposed development will comprise the construction of St. Ambrose High School including a two-storey school building with associated school pitches, car parking, play areas and soft landscaping. The current proposed development plan is provided as Drawing 5311/E/002, Appendix A.

1.2 Background

Ramboll UK understand 1No. desk study (Phase I) and 2No. intrusive site investigations (Phase II) have been undertaken within the site boundary since 2005; available reports and investigations for the site are outlined below:

- St. Ambrose High Desk Study (URS, 2005);

- Preliminary Ground Investigation Report, St. Ambrose High School, Coatbridge (URS, 2006);

- Proposed St. Ambrose High School, Ground Investigation Report (URS, 2008); and

- Proposed St. Ambrose High School, Additional Gas Monitoring (URS, 2009)

A review of these reports was undertaken by WSP (2009) on behalf of North Lanarkshire Council’s Environmental Department and is detailed in the letters outlined below and provided in Appendix B:

- Report Review – Proposed St. Ambrose High School, WSP 17th November 2008;

- Proposed St. Ambrose, Townhead Report Review Summary and Recommendations, Environmental Services 18th November 2008 (incl. URS response to comments); and

- Report Review Follow Up – St. Ambrose High School, WSP 31st August 2009.

The additional investigation works undertaken by Ramboll and detailed in this report are to supplement the existing site data and provide additional information across the site. This data will inform a full, robust environmental risk assessment for the proposed St. Ambrose School and address the concerns raised by WSP (2009).

1.3 Objectives

The objectives of the supplementary site investigation works and report were to further establish the environmental ground conditions in the area of the proposed soakaways, undertake additional shallow soil analysis to address data gaps within the URS report in order to fully address the risks to Human Health and provide a Ground Contamination Risk Assessment for the proposed development using all available data and address the concerns raised by WSP (2009).

In order to achieve these objectives the following scope of works were undertaken:



• Site investigation comprising:

- 5No. machine-excavated trial pits to a maximum depth of 3.30mbgl (below ground level) in the areas of the proposed soakaways;

- 6No. machine-excavated trial pits to a maximum depth of 4.10mbgl across the site;

- 11No. hand excavated pits to a maximum depth of 1.20mbgl across the site;

- Soil sampling for chemical laboratory analysis; and

• Factual and interpretative reporting comprising:

- Generic quantitative risk assessment using both new and existing data to characterise contamination risks associated with the proposed development;

- Qualitative risk assessment to identify potentially significant ground contamination risks associated with the proposed development and also with regard to the construction phase of the works; and

- Development of a risk management strategy outlining significant ground contamination risks and recommendations for their mitigation.

All ground contamination assessment work has been completed in accordance with the current UK legislative framework, further details of which are provided in Appendix C.

1.4 Constraints and Limitations

This report has been prepared for the exclusive use of the Balfour Beatty for the purpose of assisting site evaluation in the context of the proposed redevelopment at the time of writing. This report should not be used in whole or in part by any third parties without the express permission of Ramboll UK Ltd. in writing.

Ramboll has endeavoured to assess all information provided to them during this appraisal. This report summarises information provided from a number of external sources and cannot offer any guarantees or warranties for the completeness or accuracy of information relied upon.



2 SITE SETTING

The site of the proposed St. Ambrose High School is located in Coatbridge, Lanarkshire. A site location plan is presented as Figure 2.1 in Appendix A.

2.1 Site Description

The site is located off Townhead Road and is bordered by Townhead Road to the north, a community centre, pavilion and residential properties to the east, Drumpellier Park to the south and a Golf Course to the west.

The site is located at the approximate National Grid Reference (NGR) 271546, 665970 and occupies an area of approximately 13.5Ha. Currently the site is occupied by numerous sports pitches and is in use by the general public as a recreational area. An area of car parking and an access road is present in the northeast of the site. A current site layout plan indicating current topographic levels is included in Appendix A as Drawing 5311/E/003.

2.2 Site History

This summary of the site history has been compiled using the available Ground Investigation Reports (URS, 2006; 2008). According to this information, the site remained in use as rough pasture in a mining area with a railway crossing the north of the site and the eastern site boundary and coal pits to the northeast and southeast of the site until the 1890s when the railway in the north was dismantled and a mineral railway was constructed across the southern area of the site.

By 1912 a reservoir was present to the southeast of the site boundary and 2No. tanks were located northeast of the site. Residential developments were constructed to the north of the site by the 1930s and the railway was dismantled.

The site was then used as a landfill from 1945-1972. Information obtained from North Lanarkshire Council indicate that Townhead Landfill received an estimated half million tonnes of domestic refuge from Coatbridge and 77,000 gallons of wet sewage and unspecified residue from Gartsherrie Steel Works were disposed of annually for an unknown period of time. By the 1990s the site was in use as playing fields following remodelling and has remained so up to the present day. No further details are available regarding the capping of the landfill and development of the playing fields.

2.3 Geology

Based on the information obtained from previous site investigations (URS, 2006; 2008); the geology underlying the site is understood to comprise Made Ground including topsoil overlying probable landfill material up to a maximum depth of 8.45mbgl. No significant capping layer is present above the probable landfill material. Underlying the Made Ground are superficial deposits of peat, glaciolacustrine clay, silt and sand and glacial till to a maximum depth of 23.2mbgl. These superficial deposits overlie the solid geology of the Middle Coal Measures, reported at depths between 7.40mbgl and 23.20mbgl and comprise sandstone and mudstone with occasional bands of coal.

The site is underlain by several coal seams, some of which have been historically mined by shallow workings. In addition, mine shafts have been identified in and



around the site. The potential geotechnical risks from mining instabilities are not discussed further in this report.

2.4 Hydrogeology & Hydrology

The previous investigations (URS, 2006; 2008) indicate that the solid geology underlying the site is classified as moderately permeable according to the Scottish Environmental Protection Agency (SEPA). This is comparable to the Environment Agency (EA) classification of a Secondary Aquifer. The site is not within a source protection zone.

During the URS investigations in 2006 and 2008, groundwater was typically recorded at the superficial to solid interface at depths ranging from 12.80 to 23.20mbgl. It is understood that this is the underlying aquifer. Perched shallow groundwater was also reported across the site within the Made Ground and superficial deposits, although typically, perched groundwater was reported above the peat at depths ranging from 1.90 to 4.70mbgl.

There are various drains labelled on the site plan located southwest of the site with Drumpellier Country Park, the nearest being approximately 10m from the southwest site boundary. On investigation, these are surface ditches, typically dry, which are likely to fill with water during heavy rain. A photograph is included in Appendix A as Figure 2.2. The nearest surface water receptor is therefore Monkland Canal, which runs east to west and lies approximately 350m south of the site and Lochend Loch and Woodend Loch lie approximately 450m west and 650m northwest of the site boundary respectively.

2.5 Flood Risk

The Scottish Environmental Protection Agency’s indicative floodplain map shows that the site does not lie within an area of potential risk from river or sea flooding. The nearest area in the vicinity of the site at risk of flooding lies approximately 150m northeast of the site boundary.

2.6 Ground Gas

There is a potential for the build up of potentially hazardous ground gas across the site. The site has previously been used as a landfill and there is a layer of peat across the majority of the site; both of which have the potential to generate potentially hazardous ground gases. In addition, the site is in an area associated with mining and therefore there is a potential for potentially hazardous mine gases to be generated. The source of the very high methane concentrations is the natural peat deposits underlying the site

Due to the potential risks from ground gas in the context of the proposed development, 4No. ground gas monitoring visits were undertaken as part of the initial investigation (URS, 2006) between August and October 2006. Maximum concentrations of 12.6% carbon dioxide, 4.0% methane and a maximum flow rate of 2.5l/hr was recorded during these monitoring visits.

An additional 4No. rounds of monitoring were undertaken following the URS investigation (2008) during August 2008 and maximum concentrations of 30.2% carbon dioxide, 68.7% methane and a negligible flow rate were recorded during these monitoring visits. It is considered unlikely that no flow rate would occur across



the site during all 4No. monitoring rounds therefore the negligible flow rates reported during these visits are considered to be invalid.

An additional 12No. rounds of monitoring were carried out between November 2008 and April 2009. Maximum concentrations of 32.2% carbon dioxide, 75.4% methane and a maximum flow rate of 10.9l/hr were recorded during these monitoring visits.

Based on current guidance, these results would classify the site as Characteristic Situation 4. However, URS argued that the high flow rate reported (10.9l/hr) was a spurious result as it only occurred once, from one borehole and therefore the next highest flow rate reported (1.8l/hr) should be used when classifying the gas regime on the site. Using this flow rate, the site would be classified as Characteristic Situation 3.

This classification was not deemed appropriate by the Environmental Services Department at North Lanarkshire Council as they considered the 10.9l/hr flow rate reported was a valid result and therefore should be incorporated into the ground gas assessment. Therefore the gas regime on site is considered to be representative of Characteristic Situation 4 and appropriate protection measures should be incorporated into the proposed development.

2.7 Previous Ground Investigations

Site investigations were undertaken on site by URS in 2006 and 2008 and interpretation of geoenvironmental ground conditions was provided by URS in 2008. Data from these investigations has been incorporated into this report to inform a full, robust assessment of the potential risks to Human Health and Controlled Waters that may exist on site based on the proposed development.

The preliminary investigation in 2006 comprised:

• 10No. machine-excavated trial pits to depths of 2.30-4.90mbgl; • 7No. cable percussive boreholes to depths of 5.00-11.50mbgl; • 4No. rotary boreholes to depths of 26.70-39.00mbgl; • 4No. rounds of ground gas monitoring; • Geotechnical and environmental sampling and analysis; and • Factual Reporting.

The main investigation in 2008 comprised:

• 17No. cable percussive boreholes to depths of 7.05-15.50mbgl; • 10No. rotary boreholes to depths of 39.40-47.30mbgl; • 105No. machine-excavated trial pits to depths of 2.00-4.30mbgl; • Geotechnical and environmental sampling and analysis; • 1No. round of groundwater monitoring and sampling; • 4No. rounds of ground gas monitoring; and • Factual and Interpretative Reporting

A plan illustrating all the exploratory hole locations is included in Appendix A as Drawing 5311/E/001.

2.8 Preliminary Conceptual Model

Risk from contamination is assessed by consideration of possible linkages between contaminant sources and potential receptors which could be harmed or polluted. The key aspect of the UK contaminated land framework is the development of a



conceptual model which illustrates the spatial interaction between the potential sources and receptors on site. Sources, receptors and pathways are defined as:

• A source, i.e., a substance that is capable of causing pollution or harm; • A pathway, i.e. a route by which the contaminant can reach the receptor; and • A receptor (or target), i.e. something which could be adversely affected by

the contaminant.

Further details of the current UK contaminated land framework for contamination assessment are provided in Appendix C.

2.8.1 Sources

A review of historical and current land use on site and in the surrounding area has been undertaken. Potential contamination sources and actual sources of contamination (as identified in the previous site investigations) are summarised below:

Table 2-1: Potential/actual sources of contamination

Source Potential/actual

contaminant and/or hazard

Description/properties

Made Ground

(Landfill)

Heavy metals, Polycyclic Aromatic Hydrocarbons (PAHs), hydrocarbons,

Volatile Organic Compounds (VOCs) Semi-Volatile Organic Compounds

(SVOCs), asbestos and ground gas

Elevated concentrations of various contaminants including lead, nickel, arsenic, cyanide, chromium, benzo(a)pyrene, dibenzo(a,h)anthracene and aromatic EC21-35 hydrocarbons were identified in isolated areas of Made Ground across the site. This material is also known to be generating potentially hazardous ground gases.

There is a potential for contaminants to exist in areas of site not previous investigated.

Mining including railways

Heavy metals, inorganics, hydrocarbons, PAHs,

asbestos and ground gas

Elevated concentrations of various contaminants including lead, nickel, arsenic, cyanide, chromium, benzo(a)pyrene, dibenzo(a,h)anthracene and aromatic EC21-35 hydrocarbons were identified in isolated areas of Made Ground across the site. Some of these contaminants may have been generated as a result of the mining activities on site.

In addition potentially hazardous ground gases may be generated from the coal seams and former mining activities on site.


Peat Ground Gas Peat underlies the majority of the site and is known to be generating potentially hazardous ground gases.

2.8.2 Pathways

In order for contaminants to reach potential receptors, there has to be a viable route for the contaminant. Potential pathways considered given the nature of the proposed development and the potential contaminative sources identified:

• Dermal contact with soils; • Ingestion of soils; • Inhalation of dust and vapours; • Plant root up-take;



• Migration of ground gases; and • Leaching and subsequent migration of groundwater.

2.8.3 Receptors

The site-specific receptors that could potentially be affected by the hazards identified in relation to the current and future use of the site for a school with areas of soft landscaping:

Human Health

• Current and future site users; and • Site development workers.

Environmental

• Moderately Permeable Aquifer (Middle Coal Measures); • Monkland Canal approximately 350m south of the site boundary; • Structures and services; • Adjacent properties; and • Plants and vegetation.

2.8.4 Summary

The most significant potential pollutant linkages identified are:

• Direct contact with potentially contaminated Made Ground soils by future site users and construction workers;

• Leaching of contaminants into underlying groundwater and subsequent vertical migration into the underlying aquifer or lateral migration into surface water receptors;

• Migration and accumulation of potentially hazardous ground gases in confined spaces resulting in asphyxiation or explosion; and

• Inhalation of airborne dust or fibres associated with demolition material within the Made Ground.



3 SITE INVESTIGATION

3.1 Design

The site investigation was designed as a supplementary investigation in order to supplement the existing site data and provide a full assessment of the nature and extent of any ground contamination on site, addressing the concerns raised by WSP (2009). The investigation was undertaken and supervised by Geotechnics Ltd. on behalf of Ramboll UK and exploratory hole logs were produced by a Ramboll Environmental Consultant and logged in accordance with BS 5930.

The objectives of the supplementary site investigation were as follows:

• Identify any potential contaminants and their potential leaching capacity across the site that may be associated with former land-use in areas not previously investigated;

• To provide additional environmental information about the topsoil and shallow Made Ground material across the site;

• Identify any potential contaminants and their potential leaching capacity in the areas of the proposed soakaways; and

• Provide additional information on shallow environmental ground conditions across the whole of the site.

3.2 Site Investigation Activities

The supplementary site works were carried out on the 24th September and the 1st-2nd October 2009 by Geotechnics Ltd. The investigation comprised the following scope of works:

• 5No. machine-excavated trial pits to a maximum depth of 3.30mbgl (below ground level) in the areas of the proposed Soakaway;

• 6No. machine-excavated trial pits to a maximum depth of 4.10mbgl across the site;

• 11No. hand excavated pits to a maximum depth of 1.20mbgl across the site; and

• Soil sampling for chemical laboratory analysis.

The locations of the exploratory holes are shown on Drawing 5311/E/001 in Appendix A. Exploratory hole logs are presented in Appendix D, and laboratory chemical analysis results are presented in Appendix E.

3.3 Limitations

Various limitations were experienced whilst undertaking the site investigation. These included the following:

• The machine-excavated trial pits had to be located outside of the current playing fields to avoid any damage as these pitches are still in use by the general public.

It should be noted that although every effort has been made to ensure the accuracy of the data obtained from the investigation, the possibility exists for variations in ground and groundwater conditions between and around exploratory hole locations. In addition, groundwater levels are likely to vary seasonally and with changes in



weather conditions.

3.4 Laboratory Chemical Analysis

A total of 71No. soil samples were despatched to the Derwent Environmental Testing Services (DETS) laboratory in County Durham. DETS is a UKAS and MCERTS accredited laboratory.

37No. soil samples (plus 1No. duplicate) were scheduled by Ramboll UK for chemical analysis, including the following suite of determinands based on historical site use, the findings of previous site investigations, guidance given in the DoE Industry Profiles and CLR8, and on professional experience:

• Speciated Polycyclic Aromatic Hydrocarbons (PAH) (US EPA priority PAHs); • Extractable Petroleum Hydrocarbons (EPH); • Metals (arsenic, cadmium, chromium, copper, nickel, lead, zinc, mercury,

boron and selenium); • Sulphide, Sulphate and Sulphur; • pH; and • asbestos in Made Ground strata.

In addition, 8No. soil samples were scheduled for analysis of fraction of organic carbon (foc), 10No. samples were scheduled for speciated Total Petroleum Hydrocarbon (TPH) analysis and 2No. samples were scheduled for Volatile Organic Compound (VOC) and Semi Volatile Organic Compound (SVOC) analysis.

18No. soil samples were also scheduled for leachate analysis, for the suite of determinands as detailed below:

• Metals, Cyanide, pH, Sulphate and Sulphide; • Phenols; • Hardness as CaCO3; • PAHs (USEPA 16No. priority Polycyclic Aromatic Hydrocarbons); and • Extractable Petroleum Hydrocarbons (EPH).

Laboratory chemical analytical results are presented in Appendix E.

3.4.1 Quality Assurance/Quality Control analysis

Duplicate soil sampling results are illustrated in Table 3-1:

Table 3-1: Comparison of Duplicate Soil Sample Analyses

Determinand HDP11

(mg/kg) D1

(mg/kg)

Arsenic 17 17

Cadmium 1.8 2

Chromium 32 57

Chromium (Hexavalent) < 1 < 1

Copper 200 290

Lead 580 480

Mercury 0.14 0.14

Nickel 120 150

Selenium 0.9 0.9

Zinc 620 600



Determinand HDP11

(mg/kg) D1

(mg/kg)

Boron 2.7 2.5

Sulphate (Total) 0.17 0.11

Sulphur (Total) 0.12 0.09

Sulphide 48 44

pH 7.6 7.5

EPH 620 670

Acenaphthene < 0.1 0.3

Acenaphthylene < 0.1 < 0.1

Anthracene 0.4 0.7

Benzo(a)anthracene 0.7 0.9

Benzo(a)pyrene 0.9 0.9

Benzo(b)fluoranthene 0.3 0.3

Benzo(k)fluoranthene < 0.1 < 0.1

Benzo(g,h,i)perylene 0.4 0.5

Chrysene 0.7 0.9

Dibenzo(a,h)anthracene < 0.1 < 0.1

Fluoranthene 0.8 0.9

Fluorene < 0.1 0.4

Indeno(1,2,3-c,d)pyrene 0.4 0.7

Naphthalene < 0.1 < 0.1

Phenanthrene 0.8 1.6

Pyrene 1 1.1

PAH 6.5 9.2

Duplicate sample analysis is used to provide an indication of the precision of the analytical results, i.e., the repeatability of the laboratory analytical process. The results of the duplicate analyses are compared with the original sample data. If the results of the sample and duplicate analyses are similar (i.e., within ±30%), it is generally considered that an acceptable standard of repeatability has been maintained in the sampling and analytical process, and that the results can therefore be described as being precise. Only PAH results show a discrepancy of >30% likely due to variations in coal and clinker identified in this location. Considering the remainder of results are within ±30% results are considered precise.



4 GROUND CONDITIONS

4.1 General Stratigraphy

Reference has been made to the supplementary investigation recently undertaken by Geotechnics Ltd. and previous investigations undertaken by URS (2006; 2008). Exploratory hole logs and chemical analysis data from the URS investigation (2006) are presented in Appendix F and data from the URS investigation (2008) are presented in Appendix G for reference.

Exploratory hole logs from the supplementary investigation and logged by Ramboll UK (to BS5930) are presented in Appendix D. An Exploratory Hole Location Plan is included as Drawing No. 5311/E/001 in Appendix A.

The ground conditions encountered during the site investigation works are summarised in Table 4-1 below. Only the dominant soil types are included and summary descriptions have been used:

Table 4-1: Stratigraphic Succession

Strata Description Min. Depth

encountered (mbgl)

Depth to base

(mbgl)

Maximum thickness

(m)

Made Ground (Topsoil)

Silty Sand/Sandy Silt (dark brown silty fine sand and sandy silt with frequent rootlets and occasional gravel).

0.00 0.00-0.60 0.60

Made Ground (Reworked Topsoil)

Sandy Gravelly Silt (dark brown slightly gravelly sandy silt. Gravel is subangular to subrounded fine to coarse of coal, clinker, sandstone, glass and other minor constituents. Sand is fine to medium) 0.05 0.10-0.50 0.30

Silty Sand (dark brown silty fine to medium sand)

Made Ground (Probable Landfill)

Sandy Gravel (red-brown to brown-grey sandy angular to rounded fine to coarse gravel of ash, sandstone, burnt shale, coal, glass, bottles and jars, porcelain, newspaper, slag, wood and numerous other minor constituents depending on location.)

0.00 0.90-6.101

6.00 Gravelly Sand (red-brown to brown-grey gravelly fine to coarse sand. Gravel is angular to rounded fine to coarse gravel of ash, sandstone, burnt shale, coal, glass, bottles and jars, porcelain, newspaper, slag, wood and numerous other minor constituents depending on location.)

Superficial Deposits

Peat (Soft brown to red-brown spongy to amorphous fibrous peat.)

1.40 3.50-9.60 5.50

Sandy Gravelly Clay (soft to stiff brown to grey gravelly sandy clay. Sand is fine. Gravel is angular to rounded fine to coarse of sandstone, shale, coal, charcoal and quartzite.)

0.00 3.00-23.20

23.20

Gravelly Sand (grey to orange-brown silty slightly gravelly fine to medium sand. Gravel is subangular to rounded fine to coarse of sandstone and charcoal.)

2.90 3.10-11.90

2.35

Silt (very soft to firm grey and brown sandy silt. Sand is fine.) 4.00

7.10-13.70

4.20




encountered (mbgl)

Depth to base

(mbgl)

Maximum thickness

(m)

Middle Coal Measures (interbedded sandstone, mudstone and coal)

Sandstone (moderately strong to strong light grey to white fine to coarse grained sandstone with occasional mudstone laminations.)

6.5-23.20 Not

proven Not

proven

Mudstone (laminated dark grey mudstone with occasional carbonaceous laminations and plant fossils.)

7.4-25.25 Not

proven Not

proven

Coal (Moderately weak to weak dark grey coal with occasional laminations of carbonaceous mudstone.)

23.30-25.05 Not

proven Not

proven

1 Made Ground persists to a maximum of 10.80mbgl and 13.60mbgl in R04 and R03 (2006) respectively. This is described in drillers logs as “Made Ground (ash, peat and clay)” immediately overlying the bedrock. This description is considered likely to be a Driller’s combined description of the Made Ground and underlying superficial deposits and therefore has been omitted from this table.

4.2 Visual and Olfactory Observations of Potential Contamination

During the previous and supplementary site investigations, visual and olfactory observations of potential contamination were observed in a number of exploratory holes, as summarised in Table 4-2. Ash is not included in the table as it was commonly encountered as gravel in Made Ground.

Table 4-2: Visual and Olfactory Evidence of Potential Contamination

Description of Observed Potential

Contamination

Exploratory Hole No.

Depth (mbgl) Description of Strata

Slight organic odour

TP1 (2006) 0.70-0.90 Made Ground: Light grey brown CLAY with small pockets of fibrous peat and coal.

TP101 (2009) 0.35-0.45 Made Ground: Dark brown to red-brown very gravelly fine to coarse SAND.

TP03 (2009) 2.30-3.00 Soft dark brown to dark grey slightly gravelly silty CLAY.

Moderate organic odour

TP04 (2009) 1.50-2.40 Soft very dark brown occasionally mottled grey and black slightly sandy SILT/CLAY.

Moderate to heavily decomposed organic material (with moderate to strong rotting odour in TP102)

TP102 (2009) 1.70-3.80 Made Ground: Pale to dark grey and orange very sandy GRAVEL.

HDP07 (2009) 1.00-1.10 Made Ground: Dark brown to green-brown heavily decomposed organic material.

Moderate hydrocarbon odour


TP101 (2009) 0.80-2.90 Made Ground: Firm dark brown to grey-brown gravelly CLAY.

TP238 (2008) 3.40-4.10 Made Ground: Dark grey slightly clayey cobbly SAND and GRAVEL.

Slight hydrocarbon odour

TP102 (2009) 0.90-1.35 Made Ground: Firm dark brown very gravelly CLAY.

Slag 46No. exploratory

holes Depths ranging from

0.00-6.00 Within Made Ground (probable landfill material)

Clinker 22No. exploratory






Contamination



Tarmacadam BH202 (2008) 0.05-0.70 Made Ground: Brown sandy gravelly CLAY.

Bitumen TP231 (2008) 2.90-3.90 Made Ground: Dark brown to grey clayey cobbly SAND and GRAVEL.

4.3 Groundwater Occurrence

Groundwater strikes were encountered typically at the interface between the superficial and solid geology at depths ranging from 10.80mbgl to 23.20mbgl. It is likely that this represents the underlying Secondary Aquifer.

Groundwater strikes were also encountered within the Made Ground across the site, perched over the peat at depths ranging from 1.50mbgl to 4.90mbgl.

Groundwater was also encountered in some of the gravelly clay and silt deposits in localised areas across the site at depths ranging from 2.80mbgl to 11.00mbgl.

No groundwater monitoring was undertaken as part of the supplementary investigation although groundwater monitoring was undertaken during the previous investigations. Wells were installed into the Made Ground and superficial deposits across the site at depths ranging from 0.50-11.50mbgl (URS, 2008). Groundwater was reported in these wells at depths between 1.61-4.91mbgl within Made Ground and between 2.45-8.14mbgl within the superficial deposits. See Section 2.4 for further details of the groundwater regime across the site.



5 GROUND CONTAMINATION ASSESSMENT

This ground contamination assessment has been undertaken in accordance with the current UK framework and comprises a generic quantitative risk assessment as defined in CLR 11. Further details of the legislative framework and CLR11 are provided in Appendix C.

In order to assess the significance of the chemical concentrations reported, generic assessment criteria (GAC) must be selected based on the critical receptors identified at the site. Receptors are considered in relation to Human Health (e.g., people using the site) and Controlled Waters (e.g., water resources).

Potential risks to Human Health from soil impacts are considered using the measured soil concentrations. Potential risks to Controlled Waters are considered using soil leachate concentrations as indicative of the potentially mobile fraction of any soil impact and also measured groundwater concentrations.

5.1 Human Health Assessment

5.1.1 Methodology

Details of the UK framework for human health risk assessment and GAC are provided in Appendix C. GAC are provided for 3 standard land uses only: residential, allotments and commercial.

The site is proposed to be redeveloped as a secondary school (for 11-18 yr olds), with associated playing fields, parking, play areas and soft landscaping. This site has therefore been classified for the purposes of the screening assessment as residential without home-grown produce according to current UK guidance.

Contaminant concentrations below the adopted GAC are considered not to warrant further risk assessment. Where any concentrations are recorded above the GAC consideration of the contaminant distribution is undertaken and statistical analysis used where appropriate.

5.1.2 Soil Screening Analysis

Chemical analysis screening summary tables are held in Appendix H, detailing the measured concentrations of potential contaminants in comparison with the applicable GAC for a residential land use based on current UK guidance (2009). These tables combine chemical data from the initial investigations in 2006 and 2008 (URS) with data from the recent supplementary investigation (RUK, 2009).

Measured concentrations above the recommended GAC are highlighted within the tables (Appendix H) and Table 5-1 provides a summary of these exceedences.

Table 5-1: Summary of Soil Exceedences Compared with Relevant GAC

Determinand GAC

(mg/kg)

No. of Samples (MG and Natural)

No. of Exceedences

Maximum (mg/kg)

Arsenic 35 82 5 71

Lead 450 82 18 6600

Nickel 130 82 3 660



Determinand GAC

(mg/kg)


No. of Exceedences

Maximum (mg/kg)

pH <5, >9

(pH units) 82 3 (<pH5) 4.53 (min)

Benzo(a)anthracene 6.2 79 5 14

Benzo(a)pyrene 1 79 22 34

Benzo(b)fluoranthene 7.4 79 1 9.3

Chrysene 10 79 1 11

Dibenzo(ah) anthracene

0.93 79 7 5.3

Indeno(1,2,3-c,d)pyrene

4.4 79 3 6.6

Aromatic C21-C35 1300 49 3 1900

EPH 1300* 35 4 6400

*GAC for Extractable Petroleum Hydrocarbons based on that for Aromatic >C21-C35, representing a conservative estimate of the typical hydrocarbon fraction likely to cause harm to human health.

The majority of exceedences detailed in Table 5-1 above are from Made Ground soils only including landfill, topsoil and reworked topsoil, with the following exceptions:

• Acid conditions and elevated hydrocarbons (aromatic C21-C35) concentrations in peat from BH210 (5.3mbgl), TP307 (2.2mbgl) and BH302 (3.3mbgl).

• Elevated EPH, benzo(a)pyrene and dibenzo(a,h)anthracene was reported at 2.8mbgl in the peat from TP01 (2009); and

• Elevated EPH was reported at 2.6mbgl in the organic-rich clay from TP03 (2009).

Asbestos None of the 46No. samples scheduled for asbestos analysis were found to contain asbestos-containing materials.

Volatile Organic Compounds (VOC) and Semi Volatile Organic Compounds (SVOCs) None of the 4No. samples scheduled for VOC and SVOC analysis were found to contain concentrations of any VOCs of SVOCs above the laboratory detection limit.

5.1.3 Soil Contaminant Distribution Assessment

Identified metal and hydrocarbon impacts are considered further in relation to vertical and lateral distribution across the site and through statistical analysis, if considered appropriate.

Metals

Arsenic was reported as elevated in 5No. samples of Made Ground considered to be probable landfill material at depths ranging from 0.70mbgl to 5.00mbgl.

Lead was reported at elevated concentrations in 17No. samples of probable landfill material and 1No. sample of reworked topsoil at depths ranging from 0.30mbgl to 5.00mbgl. It is likely that these elevated concentrations are attributable to the ash reported in the probable landfill material reported in these locations and across the site.

Elevated concentrations of nickel were reported in 3No. samples of Made Ground considered to be landfill material at depths ranging from 2.00mbgl to 5.00mbgl.



pH

Acidic conditions ranging from pH 4.53 were reported in 3No. samples of peat from across the site at depths ranging from 2.20-5.30mbgl. Peat is naturally acidic and the pH of this stratum is typically lower than in other strata across the site. However, as the average pH for the peat across the site is 5.83 and within the recommended GAC range for the proposed development therefore there is not considered to be a significant risk from acidic conditions within the peat.

The pH recorded within the shallow soils was within the recommended GAC range for the proposed development.

Polycyclic Aromatic Hydrocarbons

Significantly elevated concentrations of a variety of Polycyclic Aromatic Hydrocarbons (PAHs) were reported in Made Ground (including topsoil and landfill material) from across the site and in 1No. sample of peat from across the site.

More significantly elevated concentrations of PAHs are reported within the topsoil and reworked topsoil and the elevated concentrations within the peat are of a different composition.

Hydrocarbons

Elevated hydrocarbon (EPH) concentrations were reported in 4No. samples. 1No. from probable landfill material in HDP05 at 1.00mbgl, 1No. from reworked topsoil in HDP07 at 0.25mbgl, 1No. from peat in TP01 at 2.80mbgl and the most significant from natural clay in TP03 at 2.60mbgl reported as having a slight organic odour. Speciated data was also obtained from this sample and the concentrations of total aliphatic/aromatic hydrocarbons C5-C35 amounts to 130mg/kg. Therefore, it is considered likely that the elevated hydrocarbons reported are within the heavy-end fraction of hydrocarbons (>C35).

In addition, elevated concentrations of speciated hydrocarbons (Aromatic C21-35) were reported in 3No. samples of peat at 5.30mbgl (BH210), 2.20mbgl (TP307) and 3.30mbgl (BH302).

With the exception of the significantly elevated EPH concentrations is TP03 considered to be attributable to localised source impacts, the other elevated concentrations are considered likely to be representative of the material across the site. Therefore it is considered appropriate to undertake statistical analysis for the probable landfill material, reworked topsoil and peat deposits.

Screening Summary

Exceedences of the above contaminants are typically widespread, with no significant lateral variations in concentrations identified across the site although variations between material types were identified. These elevated concentrations are therefore considered likely to reflect the wider distribution of concentrations through each deposit type across the site, thus statistical analysis is considered appropriate for each material type to further assess the potential risk to Human Health.

Statistical Analysis The statistical assessments are used to calculate representative concentrations (defined as the 95% Upper Confidence Limit) of those determinands recorded at elevated concentrations across the site. The 95%UCL is then compared to the GAC to determine if there is a significant impact on site. Outlier tests are also completed.



This statistical analysis is completed based on CIEH guidance (2008) and further details of the statistical methods of analysis are provided in Appendix C.

Table 5-2 to Table 5-4 (below) summarises the conclusions of the statistical assessment.

Table 5-2: Summary of identified impacts within Made Ground (probable landfill material)

Contaminant GAC (mg/kg)

Upper Confidence Limit (excluding outliers)

(mg/kg) Outliers Assessment

Arsenic 35 28.32 None No significant impact

Lead 450 415

6600mg/kg in BH308 at 2.00mbgl


1400mg/kg in TP102 at 1.80mbgl

3No. potential hotspots

Nickel 130 97.74 660mg/kg in BH312

at 5.00mbgl 1No. potential hotspot

Benzo(a) anthracene

6.2 2.63 None No significant impact

Benzo(a)pyrene 1 2.31 None Potential site-wide impact

Benzo(b) fluoranthene


Chrysene 10 2.88 None No significant impact

Dibenzo(a,h) anthracene


Indeno(1,2,3-c,d)anthracene


EPH 1300* 1011 None No significant impact

*Based on conservative GAC values (see note in Table 5-1)

Within the probable landfill material across the site there are identified site-wide impacts of benzo(a)pyrene and localised impacts of nickel in BH312 at 5.00mbgl and lead in BH308, BH210 and TP102 at depths of 2.00mbgl, 4.00mbgl and 1.80mbgl respectively.

Table 5-3: Summary of identified impacts within Made Ground (topsoil and reworked topsoil)




Lead 450 240 650mg/kg in TP102


Benzo(a) anthracene 6.2 8.61 None Potential site-wide impact







Within the topsoil and reworked topsoil material across the site there are identified site-wide impacts of benzo(a)anthracene and benzo(a)pyrene and a localised impact of lead in TP102 at 0.30mbgl.



Table 5-4: Summary of identified impacts within Peat




Benzo(a)pyrene 1 0.45 34mg/kg in TP01 at

2.80mbgl 1No. potential hotspot


0.93 0.02 5.7mg/kg in TP01


Aromatic C21-35

1300 1289.49 None No significant impact

Within the peat across the site there are identified localised impacts of benzo(a)pyrene and dibenzo(a,h)anthracene in TP01 at 2.80mbgl.

5.1.4 Soil Summary

The generic screening assessment, contaminant distribution and statistical analysis and assessment following interpretation of the proposed topographic levels across the site have identified the following impacts from those contaminants identified at elevated concentrations in soils across the site.

The following impacts have been identified:

• Localised elevated concentrations of nickel in probable landfill from BH312 (5.00mbgl);

• Localised elevated concentrations of lead in probable landfill material from BH308 (2.00mbgl), BH210 (4.00mbgl) and TP102 (1.80mbgl);

• Localised elevated concentrations of lead in reworked topsoil from TP102 (0.30mbgl);

• Site wide impact of benzo(a)pyrene within probable landfill material and topsoil;

• Site wide impact of benzo(a)anthracene within topsoil material; and

• Localised elevated concentrations of benzo(a)pyrene and dibenzo(a,h)anthracene in peat from TP01 (2.80mbgl).

5.2 Controlled Waters Assessment

5.2.1 Methodology

Details of the methodology used to define GAC are provided in Appendix C.

The GAC adopted for assessment of soil leachate and groundwater are defined based on local environmental receptors.

Typically, shallow groundwater has been encountered on site overlying the peat. In addition there is a moderately permeable aquifer within the solid geology underlying the site. Groundwater within the aquifer is typically located at the solid/superficial interface. The site does not lie within a source protection zone and there are no groundwater abstractions within 250m of the site boundary.

There are various surface drains labelled on the site plan located southwest of the site with Drumpellier Country Park, the nearest being approximately 10m from the



southwest site boundary. On investigation, these are surface ditches, typically dry, which are likely to fill with water during heavy rain. A photograph is included in Appendix A as Figure 2.2. The nearest surface water receptor is therefore Monkland Canal, which runs east to west and lies approximately 350m south of the site and Lochend Loch and Woodend Loch lie approximately 450m west and 650m northwest of the site boundary respectively.

Vertical migration into the underlying moderately permeable aquifer is considered to be a potential risk and any leaching during heavy rainfall may enter the drains to the southwest of the site.

The GAC used for groundwater and leachate data is therefore the freshwater Environmental Quality Standards (EQS), or in the absence of EQS, UK Drinking Water Standards (DWS) will be used. The guideline values selected as appropriate GAC for each contaminant are presented in Appendix C.

5.2.2 Leachate Screening Analysis

Leachate analysis for the selected suite of determinands was undertaken on 18No. soil samples submitted for analysis during the supplementary site investigation (RUK, 2009). 21No. soil samples were submitted for leachate analysis during the initial URS investigations in 2006 and 2008. Chemical analysis results screening tables are held in Appendix H, detailing measured concentrations of potential contaminants in comparison with the applicable GAC. Where reported analyses exceed GAC, these are highlighted within the tables. Table 5-5 provides a summary of any exceedances.

Table 5-5: Summary of Leachate Exceedences compared with relevant GAC

Determinand GAC

(µg/l)

No. of exceedences/ No. of samples

Minimum (µg/l)

Maximum (µg/l)

Mean (µg/l)

Copper 1 26/38 <1 22 3.7 Zinc 75 4/38 <1 330 29 Ammoniacal Nitrogen 200 6/18 <20 4,900 466 Phenol 30 6/35 <0.50 8,800 683 Sulphate 400,000 1/35 1,500 540,000 43,000 Anthracene 0.02 8/33 <0.01 0.14 0.025 Fluoranthene 0.02 9/33 <0.01 0.13 0.030 Sum of 4No. PAH* 0.1 1/33 0.04 0.11 0.06 Extractable Petroleum Hydrocarbons (EPH)

10 14/18 <10 210 36

Minimum, Maximum and Mean concentrations in relation to all data *Sum of benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(ghi)perylene and indeno(123cd)pyrene

All other determinands were either reported below detection limits or were detectable at concentrations below their respective GAC.

5.2.3 Leachate Contaminant Distribution Assessment


Metals

When compared to the conservative EQS for copper (1ug/l) various samples of landfill material, topsoil and natural strata reported elevated copper concentrations.



Due to the widespread nature of these exceedences they are considered likely to be representative of deposits across the site.

4No. samples of probable landfill material reported marginally elevated concentrations of zinc across the site.

Ammoniacal Nitrogen

Ammoniacal Nitrogen is reported to be leaching in elevated concentrations from 6No. samples; 2No. samples of probable landfill material, 3No. samples from natural strata and 1No. sample of topsoil.

Phenol

Phenols were reported as significantly elevated in 6No. leachate samples; 5No. from the probable landfill material and 1No. from natural strata.

With the exception of these 6No. exceedences all other leachate samples analysed for phenols reported concentrations below or at the detection limit. In addition, all soil samples (including those with corresponding elevated concentrations of phenols in leachate) reported concentrations of phenols below detection limit. It is therefore considered unlikely that a source of phenols exists on site which may present a significant risk to Controlled Waters.

Sulphate

Sulphate is reported as marginally elevated in 1No. leachate sample from the probable landfill material.

Organics

Leachate exceedances of anthracene and fluoranthene were reported in 8No. and 9No. soil samples respectively including probable landfill material, natural clay, topsoil and peat. Typically the most significant exceedances (an order of magnitude above the respective GAC) were reported in leachate from the probable landfill material.

1No. sample of the sum of 4No. PAHs was reported to be leaching at concentrations marginally exceeding the GAC (0.11ug/l compared to the GAC of 0.1ug/l) in a sample of reworked topsoil from 0.25mbgl. Considering the marginal and isolated nature of this exceedance it is not considered to present a significant risk to controlled waters and no further assessment is required.

Leachable concentrations of EPH were reported as elevated in 14No. samples from topsoil, natural clay, peat and the probable landfill material. The most significant exceedences were reported in the leachate from peat.

Screening Summary

Exceedences of the above contaminants are widespread within leachate, with no significant lateral variations in concentrations identified across the site although variations between material types were identified. These elevated concentrations are therefore considered likely to be representative of each deposit type across the site, thus statistical analysis is considered appropriate for each material type to further assess the potential risk to Controlled Waters.



Statistical Analysis

The statistical assessments are used to calculate representative concentrations (defined as the 95% Upper Confidence Limit) of those determinands reported to be leaching at elevated concentrations across the site. The 95%UCL is then compared to the EQS (or DWS where no EQS are available) to determine if there is a significant impact on site. Outlier tests are also completed. This statistical analysis is completed based on CIEH guidance (2008) and further details of the statistical methods of analysis are provided in Appendix C.

Table 5-6 and Table 5-7 (below) summarise the conclusions of the statistical assessment. Due to the limited leachate samples available from the natural strata across the site, statistical analysis is not considered appropriate and therefore Table 5-8 summarises the distribution and extent of impacts within natural strata.

Table 5-6: Summary of identified impacts leaching from Made Ground (probable landfill material)

Contaminant GAC (ug/l)


(ug/l) Outliers Assessment

Copper 1 3.61

22ug/l from BH206 at 2.0mbgl

16ug/l from TP212 at 0.4mbgl

2No. potential hot-spots and potential site-wide

impact

Zinc 75 103 None Potential site-wide impact

Sulphate 400,000 171,000 None No significant impact

Ammoniacal Nitrogen

200 94.3

800ug/l from HDP07 at 1.00mbgl



Phenols 30 10.8 6No. ranging from

2,500ug/l to 8,800ug/l


Anthracene 0.02 0.038 0.14ug/l in TP05 at

2.6mbgl

1No. potential hot-spot and potential site-wide

impact

Fluoranthene 0.02 0.060 None Potential site-wide impact

EPH 10 47.8 None Potential site-wide impact

Within the leachate from the probable landfill material across the site there are identified site-wide impacts of copper, zinc, anthracene, fluoranthene and EPH. Localised impacts of copper, ammonium, phenols and anthracene have also been identified.

Table 5-7: Summary of identified impacts leaching from Made Ground (topsoil and reworked topsoil)




Copper 1 6.32 None Potential site-wide impact

Ammoniacal Nitrogen

200 126 280ug/l in HP02 at


Fluoranthene 0.02 0.01 0.03ug/l in TP103





Within the leachate from the topsoil and reworked topsoil material across the site there are identified site-wide minor impacts of copper and EPH and localised minor impacts of ammoniacal nitrogen in HP02 and PAHs in TP103.

Table 5-8: Summary of identified impacts leaching from Natural Strata



Minimum (µg/l)

Maximum (µg/l)

Assessment

Copper 1 3/4 <1.6 4 Similar concentrations within the peat and clay deposits

Ammoniacal Nitrogen

200 3/3 220 1,000 Most significant exceedence

from the natural clay

Phenols 30 1/4 <0.50 3,000 Only exceedence reported

from natural clay

Anthracene 0.02 2/4 <0.015 0.07 Most significant exceedences

from the peat Fluoranthene 0.02 2/4 <0.017 0.09

EPH 10 3/3 20 210

Minimum, Maximum and Mean concentrations in relation to all data

5.2.4 Groundwater Screening Analysis

Groundwater monitoring was undertaken by URS on 1No. visit in August 2008. This section provides a full assessment of the potential risks to groundwater based on all available data.

Groundwater samples were collected from 10No. installations. The installations were screened across various strata including Made Ground deposits and underlying superficial strata including the clay, silt and peat. These installations were within the response zone of the shallow groundwater within the superficial deposits, typically perched above the peat. 1No. installation in BH207 was also screened into what is considered likely to be the underlying aquifer at the solid/superficial interface.

Chemical results from groundwater monitoring visits (2008) are presented in Appendix G. Screening tables comparing the groundwater analytical results to their respective GAC are presented in Appendix H. Exceedences of these GAC are highlighted within the tables (Appendix H) and are summarised in Table 5-9 below.



Table 5-9: Summary of Water Exceedences compared with relevant GAC


The laboratory results indicate the following determinands were identified in concentrations above GAC in groundwater:

Metals

4No. groundwater samples reported concentrations of copper exceeding the conservative freshwater Environmental Quality Standard (EQS) of 1ug/l. None of the exceedences were more than an order of magnitude above the GAC although elevated copper concentrations were also reported in leachate from the topsoil and probable landfill material across the site.

Zinc was reported at marginally elevated concentrations in 3No. samples of shallow groundwater across the site. Elevated zinc concentrations were also reported in leachate from the probable landfill material across the site suggesting a mobile, leachable source of zinc may exist in the landfill material.

Manganese was reported as significantly elevated above the EQS of 30ug/l in all samples of groundwater analysed from across the site. Therefore there may be a mobile source of manganese on site.

pH

Marginally acidic conditions were reported in 1No. sample from BH210 and this corresponds to the acidic conditions reported in the peat at this location. Due to the marginal and isolated nature of this exceedance however, the pH is not considered to be a significant risk to Controlled Waters.

Ammoniacal Nitrogen

Significantly elevated ammonium concentrations were reported across the site when compared to the recommended EQS of 200ug/l. Elevated concentrations of ammonium were also found to be leaching from the probable landfill material across the site indicating there may be a potential source of ammonium within the probable

Determinand GAC

(µg/l)


Maximum (µg/l)

Minimum (µg/l)

Mean (µg/l)

Copper 1 4/10 5.3 <1.6 2.23

Manganese 30 10/10 7,800 1,600 2,802

Zinc 75 3/10 370 <5 75.9

Ammoniacal Nitrogen 200 10/10 16,000 600 4,920

pH 6.5-10 1/10 7.74 6.46 7.09

Nitrites 500 1/10 510 <300 118

Anthracene 0.02 3/10 0.065 <0.015 0.026

Fluoranthene 0.02 9/10 0.46 <0.017 0.143

Benzo(a)pyrene 0.03 6/10 0.29 <0.009 0.993

Sum of 4No. PAH* 0.1 6/10 1.06 0.05 0.373

Aliphatics >C21-C35 10 1/10 740 <10 83

Aromatics >C21-35 10 3/10 360 <10 89



landfill material from across the site.

Phenols

Elevated phenols were reported to be leaching from the probable landfill material and natural clay in isolated areas across the site at concentrations exceeding the GAC. However, phenol concentrations in the shallow groundwater were reported below detection limit therefore suggesting that there is not a significant risk to Controlled Waters from phenols.

Nitrites

Nitrites were reported as marginally elevated in 1No. sample of groundwater from BH311. Due to the marginal and isolated nature of this exceedance there is not considered to be a significant risk to Controlled Waters from nitrites.

Organics

Chemical analysis of groundwater indicates elevated concentrations of various PAHs (including anthracene, fluoranthene and benzo(a)pyrene) and heavy-end hydrocarbons within the underlying shallow groundwater.

9No. samples of groundwater reported concentrations of fluoranthene above the EQS of 0.02ug/l. 6No. of these samples also reported elevated concentrations of benzo(a)pyrene and sum of 4No. PAHs and a further 3No. of these reported marginally elevated concentrations of anthracene. Elevated anthracene and fluoranthene concentrations were also reported within leachate samples from across the site and elevated PAHs were also reported within soil samples from the landfill, topsoil and peat across the site. Therefore there is a potential for a leachable, mobile source of PAHs to exist on site.

Elevated concentrations of high-range organics including aliphatics >C21-35 were reported as elevated in localised groundwater from BH205 and aromatics >C21-35 were reported as elevated in localised groundwater from BH202, BH205 and BH211. Elevated hydrocarbon concentrations were reported in leachate from the landfill material, peat, natural clay and topsoil suggesting there may be a source of hydrocarbons on site. However, as impacts within the groundwater are localised it suggests the potential for hydrocarbons to leach and mobilise into groundwater is limited.

Concentrations of these contaminants do not indicate any lateral pattern of distribution to suggest a single, isolated source creating a plume of hydrocarbons within the shallow groundwater. Therefore it is considered likely that the material from across the site is leaching these contaminants in similar concentrations mobilising the contaminants into the shallow groundwater.

5.2.5 Controlled Waters Assessment Summary

The generic screening assessment and contaminant distribution assessment of the potential risks to Controlled Waters have identified particular contaminants at elevated concentrations in leachate and shallow groundwater across the site which may present a significant risk to Controlled Waters.

This assessment is based on the shallow groundwater as there are currently no installations appropriately screened into the underlying moderately permeable aquifer; typically located at the superficial/solid geology interface.




• Elevated concentrations of copper, zinc and anthracene are leaching at concentrations exceeding the GAC and are impacting the shallow groundwater at similar concentrations;

• Elevated concentrations of ammoniacal nitrogen are reported in leachate, typically from the probable landfill material on site but also from localised areas of natural materials and topsoil on site. Concentrations are typically more significantly elevated within the shallow groundwater on site. The significantly elevated concentrations of ammonia within groundwater are considered likely to be attributable to the breakdown of organic components within the landfill waste and subsequent leaching as no cap was placed above the waste material to minimise leaching. As the landfill is thought to have closed in 1972, it is likely that concentrations of ammonia within leachate would have been significantly higher than at present, thus increasing the concentration of ammonia within the shallow groundwater across the site. The breakdown of any organic contaminants within the landfill will be reducing over time and this is reflected in the concentrations of ammonia within the leachate;

• Fluoranthene and PAHs (sum of 4No.) are leaching at elevated concentrations most significantly from the probable landfill material across the site but also from localised areas within the topsoil and peat deposits. These contaminants are reported at significantly higher concentrations within the shallow groundwater on site and elevated concentrations of benzo(a)pyrene are also reported in groundwater although no elevated concentrations were reported within leachate (typically reported below detection limit). Higher concentrations of these contaminants within the shallow groundwater rather than leachate are likely due to the decreasing decay of organic matter within the landfill material over time, as discussed above. Benzo(a)pyrene is likely no longer being leached from organic materials within the landfill material as the bacterial decay of this organic material has occurred previously and the impacts from subsequent leaching are revealed only within the groundwater data;

• Concentrations of EPH within leachate are elevated within the landfill, topsoil and natural material across the site. However, all speciated TPH leachate data from C5-C35 reported concentrations below detection limit suggesting the only significant impacts are from heavy-end organics greater than C35. In addition, only localised impacts of heavy-end organics (greater than C21) are reported in shallow groundwater across the site. These organics are unlikely to be highly mobile within the water environment, which is demonstrated by the isolated impacts within shallow groundwater;

• Manganese is an essential element in the production of steel and it is known that waste from the Gartcherrie Steel Works was disposed of annually at the former Townhead Landfill, underlying the site. It is likely that leaching of this material within the landfill resulted in migration of manganese into shallow groundwater, therefore explaining the significantly elevated concentrations of manganese across the site. As detailed above, it is likely that manganese represents a finite source and concentrations within the leachate and the shallow groundwater will reduce over time; and

• Phenols were reported as significantly elevated in leachate from 5No. samples of probable landfill and 1No. sample of natural strata. Considering the concentrations of phenols within soils, all other leachate samples and



all groundwater samples reported concentrations of phenols below or at the detection limit it is considered unlikely that a significant source of phenols exists on site.

All site wide impacts are considered to be only marginally above the recommended GAC. Only localised impacts have been reported at slightly higher concentrations. The decreased concentrations reported in all strata indicate that there is likely to be only a limited ongoing source of leachable contaminants, which have the potential to impact the underling shallow groundwater.

5.3 Ground Gas Risk Assessment

A ground gas monitoring programme was undertaken by URS as part of the investigations in 2006 and 2008/9. An assessment of the risk presented by any potential ground gas on site was undertaken as part of the Ground Investigation Report (URS, 2008) which concluded additional ground gas monitoring would be required. 12No. rounds of ground gas monitoring were undertaken between November 2008 and April 2009 and interpreted within the letter provided in Appendix I (reference 49339729/GLLT0015, May 2009).

The section provides a full assessment of all the gas monitoring data available for the site in accordance with CIRIA C665 and BS8485, taking into accounts the comments made by URS. Further details of the assessment methodology are provided in Appendix C.

All available ground gas monitoring data is included within Appendix J. Table 5-10 provides a summary of the maximum and minimum gas concentrations and flow rates reported in each borehole monitored from 2006 to 2009.

Table 5-10: Summary of Ground Gas Monitoring Visits

Borehole Response

Zone

Depth to GW

(mbgl)

Flow rate (l/hr)*

Peak Gas Concentration (% v/v)

Max. GSV

CS (C665)

CH4 CO2 O2

Max Min Max Min Max Min Max Min

BH1 (2006) MG 2.08-4.69 2.5 0.05 0.1 <0.1 5.8 <0.1 21.6 5.8 0.145 2

BH2 (2006) MG 4.00-4.20 2.4 0.2 4.0 <0.1 12.6 <0.1 3.8 <0.1 0.302 2

BH3 (2006) MG 3.37-4.65 2.2 -0.3 0.1 <0.1 6.2 <0.1 20.8 <0.1 0.136 2

BH201 (2008) MG 3.11-3.23 <0.1 <0.1 <0.1 <0.1 1.7 0.8 18.1 16.8 0.0017 1

BH202 (2008) Peat 5.22-5.36 <0.1 <0.1 68.7 65.3 30.2 20.0 <0.1 <0.1 0.0687 2

BH203 (2008) MG 3.54-3.77 <0.1 <0.1 <0.1 <0.1 1.9 1.5 18.8 18.2 0.0019 1

BH204 (2008) Peat 2.90-3.04 <0.1 <0.1 <0.1 <0.1 2.5 1.9 18.2 17.7 0.0025 1

BH205 (2008) MG 3.94-4.04 <0.1 <0.1 3.7 2.7 4.8 2.9 13.9 13.1 0.0048 1

BH206 (2008) MG Dry <0.1 <0.1 <0.1 <0.1 2.3 1.7 18.4 17.8 0.0023 1

BH207 (2008) Silt/Clay

/Peat 4.30-4.48 <0.1 <0.1 <0.1 <0.1 0.8 0.6 20.4 20.1 0.0008 1

BH208 (2008) Peat 4.21-4.31 <0.1 <0.1 10.2 8.3 9.6 6.9 8.9 6.7 0.0102 2

BH209 (2008) MG Dry <0.1 <0.1 <0.1 <0.1 3.7 2.5 16.7 16.1 0.0037 1

BH210 (2008) Peat 6.01-6.15 <0.1 <0.1 <0.1 <0.1 0.1 <0.1 20.6 20.1 0.0001 1

BH211 (2008) MG 2.85-3.00 <0.1 <0.1 <0.1 <0.1 12.3 9.8 10.2 7.8 0.0123 2

BH213 (2008) MG 4.90-4.91 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 20.8 20.7 0.0001 1

BH301(2008) MG 2.48-2.96 <0.1 <0.1 <0.1 <0.1 3.9 2.9 16.1 15.7 0.0039 1

BH302(2008) Silt/Clay

/Peat 7.80-8.14 <0.1 <0.1 66.2 62.1 23.3 20.5 0.7 <0.1 0.0662 2



Borehole Response

Zone

Depth to GW

(mbgl)

Flow rate (l/hr)*


Max. GSV

CS (C665)

CH4 CO2 O2


BH303(2008) MG 1.61-2.21 <0.1 <0.1 0.3 0.2 18.4 16.8 1.9 1.1 0.0184 2


/Peat 3.90-4.02 <0.1 <0.1 9.1 7.9 5.1 3.9 16.9 16.3 0.0091 2

BH305(2008) Silt/Clay 6.05-6.27 <0.1 <0.1 34.8 28.9 20.0 18.7 10.5 9.7 0.0348 2

BH306(2008) MG Dry-2.55 <0.1 <0.1 <0.1 <0.1 0.4 0.1 20.7 20.4 0.0004 1

BH307(2008) MG 2.61-2.88 <0.1 <0.1 <0.1 <0.1 13.7 11.7 7.5 6.1 0.0137 2

BH308(2008) MG/Peat 2.45-3.49 <0.1 <0.1 47.4 38.9 23.2 20.7 5.8 4.2 0.0232 2

BH309(2008) Peat Dry-2.87 <0.1 <0.1 16.8 15.3 21.7 20.5 4.8 4.5 0.0217 2

BH310(2008) MG 2.03-2.49 <0.1 <0.1 <0.1 <0.1 0.6 <0.1 20.7 20.1 0.0006 1

BH311 (2008) MG 2.58-2.75 <0.1 <0.1 <0.1 <0.1 16.8 14.7 3.3 2.3 0.0168 2

BH312 (2008) MG/Peat/ Sand/Clay

Dry <0.1 <0.1 <0.1 <0.1 0.8 0.5 19.9 19.5 0.0008 1

BH313 (2008) MG Dry <0.1 <0.1 <0.1 <0.1 12.9 12.9 3.0 3.0 0.0129 2

BH201 (08/09) MG 3.12-3.28 0.2 <0.1 0.2 <0.1 14.2 0.3 19.3 1.1 0.028 2

BH202 (08/09) MG Dry-3.81 0.2 <0.1 66.9 <0.1 14.5 <0.1 19.7 <0.1 0.029 2

BH203 (08/09) MG 3.21-4.52 0.2 <0.1 3.1 0.1 9.9 1.7 16.5 <0.1 0.0198 2

BH204 (08/09) MG 2.16-2.73 0.2 <0.1 18.6 0.1 16.9 4.2 17.6 7.4 0.0372 2

BH205 (08/09) Peat 3.34-3.75 0.1 <0.1 0.5 <0.1 15.3 5.2 20.1 0.1 0.0153 2

BH206 (08/09) MG Dry-4.35 0.2 <0.1 0.1 <0.1 15.9 7.4 12.4 1.7 0.0318 2

BH207 (08/09) Peat 3.85-4.23 0.3 <0.1 <0.1 <0.1 21.7 5.0 15.1 5.3 0.0651 2

BH208 (08/09) MG 3.61-3.95 0.1 <0.1 2.8 1.9 7.6 3.5 19.3 9.5 0.0076 2

BH209 (08/09) MG Dry-4.68 0.1 <0.1 <0.1 <0.1 5.2 0.2 20.6 13.8 0.0052 1

BH210 (08/09) Silt/Clay

/Peat 4.72-6.03 0.1 <0.1 75.4 <0.1 22.7 <0.1 17.1 <0.1 0.0754 2

BH211 (08/09) Peat 2.34-2.65 0.3 <0.1 1.0 <0.1 13.0 <0.1 19.4 <0.1 0.039 2

BH213 (08/09) MG 5.08-5.46 0.7 <0.1 <0.1 <0.1 2.1 <0.1 20.9 18 0.0147 1

BH301 (08/09) Peat 2.97-2.99 0.1 <0.1 0.5 <0.1 4.0 <0.1 20.6 <0.1 0.004 1

BH302 (08/09) MG 7.61-7.90 0.2 <0.1 52.5 <0.1 23.5 <0.1 0.5 <0.1 0.105 2

BH303 (08/09) MG Dry-1.77 0.1 <0.1 9.5 <0.1 18.2 5.7 11.8 <0.1 0.0182 2

BH304 (08/09) MG 3.89-4.04 1.4 <0.1 69.1 <0.1 31.8 <0.1 10.7 <0.1 0.967 3


/Peat Dry-5.90 1.8 <0.1 62.1 1.1 32.2 1.3 18.9 3.1 1.12 3

BH306 (08/09) MG Dry-2.47 0.1 <0.1 1.1 <0.1 5.9 1.6 19.1 <0.1 0.0059 2


/Peat 2.14-2.52 0.4 <0.1 0.5 <0.1 16.2 5.3 19.5 2.0 0.0648 2

BH308 (08/09) Silt/Clay 0.79-0.79 10.9 <0.1 14.8 <0.1 20.9 2.5 18.7 2.2 2.28 3

BH309 (08/09) MG Dry-1.90 0.3 <0.1 <0.1 <0.1 3.6 0.8 20.4 17.6 0.0108 1

BH310 (08/09) MG Dry-1.83 0.2 <0.1 <0.1 <0.1 14.6 0.2 20.4 0.3 0.0292 2

BH311 (08/09) MG/Peat Dry-2.20 0.1 <0.1 <0.1 <0.1 16.0 1.8 20.3 <0.1 0.016 2

BH312 (08/09) Peat Dry-10.01 <0.1 <0.1 0.4 <0.1 5.3 0.1 20.9 9.4 0.0053 2

BH313 (08/09) MG Dry 0.2 <0.1 <0.1 <0.1 11.5 0.2 20.6 6.5 0.023 2

Worst Case Scenario 10.9 75.4 32.2 - 8.22 4

*Negative flow rates are reported at below detection limit for the purpose of calculating the GSV



From a review of the available ground gas data the concentrations reported would classify the proposed development as Characteristic Situation 4 based on a worst case scenario, assuming the highest methane concentration (75.4%) and flow rate (10.9l/hr) could occur simultaneously on site. The highest methane concentrations were reported from the natural peat deposits underlying the site.

It is considered that this is a highly conservative assessment. The elevated flow rate of 10.9l/hr was only recorded on 1No. occasion from 1No. well. In the same well flow rates were reported between 0.1l.h and negative 12.5l/hr during all other visits, suggesting the extremely elevated flow rate is an anomalous result. Typically the flow rate across the site is 0.1-1.8l/hr.

In addition, there are issues with the well which reported this elevated flow rate (BH308). This well is screened from 1.00-11.00mbgl, however water level during the first visit was reported above the screen (0.78mbgl) which may interfere with the results. Following the first visit, URS reported the bung was “jammed down standpipe” so the groundwater could not be monitored again. Therefore it is likely a combination of interference of groundwater and inappropriate monitoring of this borehole has caused this anomalous result. Omitting this anomalous flow rate would result in a worst case GSV of 1.36l/hr therefore classifying the site as CS3.

The proposed development is a sensitive end-use and there is a high risk of ground gas generation from various sources across the site. As a result of these factors and following consultation with North Lanarkshire Council, classification of the site as Characteristic Situation 4 is considered to be appropriate.



6 GROUND CONTAMINATION

6.1 Conceptual Site Model

The information presented in the previous sections of this report have been collated and evaluated to refine the initial conceptual site model for the site. This updated conceptual site model is illustrated in cross-section form in Appendix A, Drawing No. 5311/E/004.

6.1.1 Sources

The following sources of potential contamination have been identified based on the available information from the initial investigations in 2006 and 2008 (URS) and the supplementary investigation in 2009 (Ramboll):

• Potential soil contamination which may pose a risk to Human Health:

- Localised elevated concentrations of nickel in probable landfill from BH312

- Elevated localised concentrations of lead reported in probable landfill material in the area of BH308, BH210 and TP102;

- Localised elevated concentrations of lead, reported in reworked topsoil material in TP102 at 0.30mbgl;

- Site wide impacts of benzo(a)pyrene within the probable landfill material and topsoil;

- Site wide impacts of benzo(a)anthracene within the topsoil material; and

- Localised elevated concentrations of benzo(a)pyrene and dibenzo(a,h)anthracene, reported in TP01 within the peat.

• Potential leachate and groundwater contamination which may pose a risk to Controlled Waters:

• Marginally elevated concentrations of copper, zinc and anthracene within leachate from across the site, which is impacting the shallow groundwater;

• Elevated concentrations of ammoniacal nitrogen within the shallow groundwater continuing to leach from materials across the site at slightly elevated concentrations;

• Fluoranthene and PAHs (sum of 4No.) are leaching at elevated concentrations most significantly from the probable landfill material across the site;

• Localised elevated concentrations of aliphatic and aromatic C21-35 are reported in shallow groundwater and concentrations of EPH (C10-C40) are reported to be leaching at elevated concentrations from material across the site;

• Elevated manganese within the shallow groundwater across the site, likely a result of leaching from landfill material across the site;

• Elevated phenols were reported as elevated within leachate samples from isolated areas of landfill material and natural strata; and



• Elevated ground gas concentrations including methane and carbon dioxide.

6.1.2 Receptors

The site-specific receptors that could potentially be affected by the contamination hazards have been identified in the preliminary conceptual model in Section 2.6.2. Receptors include:

• Future site users – school children, staff and the general public; • Site development workers; • Underlying aquifer and surface water features; • Construction materials; • Adjacent site users and structures; and • Site vegetation.

6.1.3 Pathways

The following potential contaminant pathways are considered likely to exist on site given the nature of the site and the contamination sources identified:

• Dermal contact with and ingestion of soils; • Plant uptake;

Direct contact pathways and plant uptake will only be active in areas of landscaping with the exception of the sports pitches. The proposed make-up of the pitches includes 250mm-350mm of imported clean fill material which will be separated from the probable landfill material below by a visqueen membrane. Based on these measures across the pitches and the reported concentrations of contaminants, direct contact pathways within the areas of the sports pitches are not considered active.

As the source areas are both localised and site-wide, further consideration is given below as to the location of localised impacts within the proposed development to determine whether these pathways will be active.

The localised elevated concentrations of lead reported in probable landfill material in the area of BH308, BH210 and TP102 and nickel reported in probable landfill material from BH312 were reported in samples at depths exceeding 1.80mbgl. In addition, localised elevated concentrations of lead were also reported in topsoil material in TP102 at 0.30mbgl. However, these samples are from strata which persist to shallower depths of a minimum of 0.05mbgl and although based on current cut and fill proposals these hotspots are in areas of fill, existing site levels will need to be reduced prior to construction. The materials cut from these areas may therefore present a potential risk to Human Health via direct contact pathways.

Localised elevated concentrations of benzo(a)pyrene and dibenzo(a,h)anthracene were reported in TP01 within the peat at a depth of 2.80mbgl. These contaminants are considered to be naturally occurring within the peat and are at a depth considered unlikely to affect future site users via direct contact due to the levels of fill proposed in this area.

Site wide impacts of benzo(a)pyrene have been identified in the probable landfill and topsoil material across the site and side wide impacts of benzo(a)anthracene have also been identified in topsoil. These contaminants may therefore present significant risk in areas of soft landscaping via the direct contact pathway to future site users.

• Ground gas migration;



• Inhalation of dusts and vapours; • Leaching and subsequent migration of mobile impacts;

There will be an overall increase in hardstanding across the site and the proposed sports pitches will include a visqueen membrane and surface water drainage system, which will limit rainfall infiltration and the leaching potential of soils. In addition, across the majority of the site the probable landfill material is separated from the solid geology (and therefore moderately permeable aquifer) by peat and/or superficial clay, which is likely to restrict the vertical migration of contaminants from the shallow groundwater, into the aquifer below.

Soakaways are currently proposed in 2No. areas on site, near TP01 in the southwest area of site and underlying the pitch in the southeast corner of site near TP03, TP04 and TP05. In the southeast area of the site, marginal impacts of copper, ammonium, anthracene, fluoranthene and EPH were reported in leachate from probable landfill and natural strata in these areas. Marginally elevated concentrations of lead, dibenzo(a,h)anthracene and EPH were reported in localised soils in this area but these are not considered to be significant.

In samples from TP01 elevated EPH, benzo(a)pyrene and dibenzo(a,h)anthracene were reported in soil samples from the peat in this location. Marginally elevated anthrancene and fluoranthene were reported within leachate from the landfill material and marginally elevated copper, ammonium, anthracene, fluoranthene and EPH were reported in peat. These elevated concentrations are not considered to be significant.

Although the concentrations of benzo(a)pyrene and dibenzo(a,h)anthracene reported in the soils are significant, leachate results reported these contaminants at concentrations below detection limit, therefore suggesting this soil source is not mobile in the water environment. These concentrations of the contaminants reported within leachate are not considered to be significant.

6.2 Qualitative Risk Assessment

Potential pollutant linkages are identified using the source-pathway-receptor framework detailed above. An assessment of the potential significance of each linkage is then made by consideration of the likely magnitude and mobility of the source, the sensitivity of the receptor and nature of the migration/exposure pathways.

This qualitative hazard assessment has been undertaken in accordance with CIRIA C552: Contaminated Land Risk Assessment, A Guide to Good Practice. Further details of the methodology used and definition of the risk categories is provided in Appendix C.



Table 6-1 summarises the pollutant linkages and risk ratings associated with the proposed development.

Table 6-1: Hazard Assessment

Hazard / Pollutant Pathway Receptor Potential Severity

Probability Of Risk

Level Of Risk

Localised elevated soil concentrations of lead in topsoil, lead and nickel

in landfill material

• Dermal contact • Inhalation of Dusts

and Vapours • Ingestion

Future site users Medium Unlikely LOW

Site development workers*

Medium Low LOW /

MODERATE

• Leaching from soils • Leachate migration • Surface water run-off • Migration of

groundwater

Neighbouring properties

Mild Low LOW

Surface water (Monkland Canal; Lochs)

Medium Unlikely LOW

Secondary Aquifer Medium Unlikely LOW

• Plant root uptake Vegetation in soft landscaped areas

Mild Low LOW

Localised elevated soil concentrations of PAHs

in peat





Medium Unlikely LOW


groundwater


Mild Low LOW


Medium Unlikely LOW



Mild Low LOW

Site-wide impacts of benzo(a)pyrene in

landfill material and topsoil and site-wide

impacts of benzo(a)anthracene in

topsoil



Future site users Medium Likely MODERATE


Medium Likely MODERATE


groundwater


Mild Low LOW


Medium Unlikely LOW



Minor Likely LOW

Marginally elevated copper and zinc within

• Leaching from soils • Leachate migration • Migration of


Mild Low LOW




Probability Of Risk

Level Of Risk

leachate and shallow groundwater

groundwater Surface water (Monkland Canal; Lochs)

Mild Unlikely VERY LOW

Secondary Aquifer Mild Low LOW


Mild Low LOW

Elevated manganese, ammonia and PAH

within shallow groundwater and

leachate.


groundwater


Mild Low LOW


Medium Unlikely LOW

Secondary Aquifer Medium Low LOW / MODERATE


Mild Low LOW

Localised elevated hydrocarbons within shallow groundwater

• Migration of groundwater


Mild Low LOW


Medium Unlikely LOW



Mild Low LOW

Localised marginally elevated concentrations of EPH, PAH, ammonium

and copper within leachate in the areas of the proposed soakaway


groundwater


Mild Low LOW


Medium Unlikely LOW



Mild Low LOW

Generation of potentially hazardous ground gas

Ground gas migration

Site users Severe Likely HIGH


Severe Likely HIGH

*Given the use of appropriate PPE and health and safety precautions, risk to workers would be reduced to low.



The risks to Human Health via direct contact with lead and nickel in localised areas across the site including TP102, BH308, BH210 and BH312 are considered to be LOW / MODERATE as these materials are at depths proposed to be excavated as part of the cut and fill works.

Localised elevated concentrations of PAHs are located in areas of proposed fill with at least 600mm of fill or existing material located above the source strata. Therefore these localised impacts are unlikely to present a risk via direct contact pathways. Risks to Human Health from these impacts are therefore considered to be LOW.

Risks to human health caused by elevated benzo(a)pyrene in probable landfill and topsoil material across the site and elevated benzo(a)anthracene in topsoil are considered likely to be significant in areas of soft landscaping where there will be an active direct contact pathway. Therefore the risk to human health from benzo(a)pyrene and benzo(a)anthracene is classified as MODERATE. Risks to vegetation in any planted areas caused by plant root uptake of these contaminants are considered to be LOW.

Risks to the Secondary Aquifer underlying the site are classified as LOW / MODERATE due to the impacts of manganese, ammonia and PAH within the shallow groundwater. Risks to the underlying aquifer from the localised hydrocarbons and marginal impacts of copper and zinc already identified within the shallow groundwater are classified as LOW. Due to the significant depths of impermeable deposits including peat and clay overlying the aquifer in the majority of locations across the site it is considered unlikely that significant vertical migration of contaminants will occur.


The development proposals include increasing the area of hardstanding across the site thus reducing leaching potential and likely pathways. Based on the significant distance to the nearest surface water receptor (Monkland Canal; Lochend and Woodend Lochs all >350m from the site) and the proposed development minimising pollutant linkages, the risks to the surface water receptors are considered to be LOW.

Risks to future site users from the generation, migration and accumulation of potentially hazardous ground gases in confined spaces resulting in asphyxiation or explosion are considered to be HIGH.

6.3 Development Considerations

Activities on-site that could affect ground conditions potentially include piling operations, foundation design, earthworks, installation of underground services and provision of drainage infrastructure.

Any piled solution to foundation design should be developed in such a way so that the installation of the piles themselves does not create preferential flow pathways by which potential contamination could mobilise in the unsaturated zone.

Foundation design should take into consideration the potential to encounter aggressive ground conditions beyond those identified during the site investigation.



As the development is proposed to comprise buildings and hard-standing, with associated areas of soft landscaping, infiltration of rainwater may be reduced compared to the present situation, with limited potential for leaching and downward migration of potential contaminants to the underlying groundwater.

Soakaways are proposed in 2No. areas of site. The design of these soakaways must take into account the marginal contamination impacts identified in these areas. Although rainfall and surface water infiltration will be encouraged in these areas, the soakaways have been strategically placed towards the south of the site away from the main hub of the landfill to minimise infiltration through the landfill material. In addition, it is considered that the proposed drainage across the entire site will minimise infiltration and leaching through the landfill, therefore improving upon the current situation at the site.



7 RISK MANAGEMENT STRATEGY

7.1 Significant pollutant linkages

Potentially significant pollutant linkages have been identified during the ground contamination risk assessment. These are:

• Risks to Human Health through direct contact pathways with elevated benzo(a)pyrene in probable landfill material across the site;

• Risks to Human Health through direct contact pathways with elevated benzo(a)pyrene and benzo(a)anthracene in topsoil material across the site;

• Risks to Controlled Waters through vertical migration of contaminants including manganese, ammonia, PAH, localised hydrocarbons, copper and zinc from the shallow perched groundwater into the deep aquifer, particularly within the areas of the proposed soakaways; and

• Risks to Human Health through the generation, migration and accumulation of potentially hazardous ground gases (methane and carbon dioxide) in confined spaces resulting in asphyxiation or explosion.

No risk management strategy is proposed for site development workers as any potential risks should be managed through the implementation of standard health and safety precautions, such as the use of appropriate personal protective equipment (PPE).

7.2 Recommendations

7.2.1 Additional Assessment and Investigation

In order to further assess the potential risks to Human Health caused by the site-wide impacts of benzo(a)anthracene in topsoil and benzo(a)pyrene in topsoil and landfill material it is recommended that a Detailed Quantitative Risk Assessment (DQRA) is undertaken in order to derive more appropriate site-specific assessment criteria for these contaminants.

Further investigation into the potential risks to the underlying aquifer including additional groundwater sampling from the shallow groundwater and underlying aquifer across the site may be required in order to further assess the potential risks to Controlled Waters, particularly considering soakaways are proposed in 2No. areas of site.

7.2.2 Proposed Remedial Measures

In addition and based on the information available to date, there is likely to be a requirement for remedial action to progress the development.

The following recommendations are made in order to reduce risks to human health from identified ground gas impacts assuming Characteristic Situation 4:

a) Reinforced concrete cast in situ floor slab (suspended, non-suspended or raft) or beam and block or pre-cast concrete slab;

b) All joints and penetrations sealed; and



c) Proprietary gas resistant membrane and passively ventilated underfloor subspace or positively pressurised underfloor sub-space, oversite capping or blinding and in ground venting layer. (in accordance with CIRIA C665/ BS8485)

Ramboll have consulted with a leading contractor in the design and installation of ground gas protection systems. Based on the maximum concentrations of methane and carbon dioxide and the maximum flow rate recorded on site a high performance passively ventilated system has been designed. The proposal for this system is included in Appendix K.

In addition, hotspots of lead and nickel were identified in localised areas across the site, typically at depths exceeding 1.80mbgl. Based on current proposals these impacts are in areas of fill but prior to the fill works, material from these areas will require excavation in order to obtain finished site levels. This excavated material may present a risk to Human Health via the direct contact pathway. It is therefore proposed that during enabling works, material excavated from these areas is stockpiled separately and subjected to validation testing to establish whether the material is suitable for reuse.

There remains the potential for ground conditions to vary in areas not directly investigated.

7.3 Additional considerations for development

Cut and Fill Works Any excavation works on site may encounter volumes of potentially contaminated groundwater, which was recorded at depths ranging from 1.90mbgl to 4.70mbgl. Allowances are recommended to be made for the removal, treatment and disposal of shallow groundwater should dewatering be required during excavation.

Significant cut and fill works are proposed for the site and there is a potential for contaminated materials not previously identified to be uncovered on site. It is therefore recommended that a suitably qualified Environmental Consultant is on site during the enabling works to ensure that should any areas of apparent contamination be exposed; the material is excavated, stockpiled separately onsite and subjected to validation testing in order to ensure the material is suitable for use.

Waste Disposal Any excavation/piling may result in soils that require off-site disposal, if they are unsuitable for reuse on site. All excavated materials will be controlled waste. Further assessment will be required to establish classification (hazardous or non-hazardous) and further chemical testing (and/or pre-treatment) if disposal to landfill is considered. Some form of pre-treatment of those materials to be disposed to landfill (e.g., screening to remove oversized ‘clean’ demolition material and gravels) may significantly reduce the volume of material liable to classify as hazardous waste.

Environmental Specification It is recommended that an Environmental Specification Report is produced in order to ensure the Contractor is undertaking all enabling works in accordance with the recommendations above.

Validation Works Validation sampling will be required from all materials cut from site during enabling works in order to ensure all materials are suitable for use. These results, along with documented evidence to illustrate that the remedial measures detailed above and within the Environmental Specification have been adhered to, will need to be



documented in a Validation Report and submitted to the Environmental Department at North Lanarkshire Council.

Underground Services Laying underground services in potentially contaminated Made Ground materials has the potential to establish preferential flow pathways and therefore materials should be used appropriate to the level of contamination identified on site, particularly with regard to underground mains water supply. Consultation with Scottish Water is advised.

Asbestos No asbestos-containing material (ACM) has been identified on site. However, as the site has been historically redeveloped and used as a landfill, localised deposits of asbestos-containing materials have the potential to be present in Made Ground across the site. Appropriate health and safety precautions (i.e., provision of appropriate PPE to site development workers, etc.) should be adopted during enabling works.


5311.E.GQRA.1A Appendices

8 REFERENCES

BS 5930 (1999) Code of Practice for Ground Investigation

BS 8485 (2007) Code of practice for the characterization and remediation from ground gas in affected developments. British Standards Institute 2007

CIRIA 552 (2001) Contaminated land risk assessment – a guide to good practice. London

CIRIA C665 (2007) Assessing risks posed by hazardous ground gases to buildings. London

Contaminated Land: Applications in Real Environments (CL:AIRE) and Chartered Institute of Environmental Health (CIEH) (2008) Guidance on Comparing Soil Contamination Data with a Critical Concentration (May 2008)

Department for Environment, Food and Rural Affairs (DEFRA) and the Environment Agency (EA) (2002) CLR 8: Potential Contaminants for the Assessment of Land

Department for Environment, Food and Rural Affairs (DEFRA) and the Environment Agency (EA) (2002) CLR 11: The Model Procedures for the Management of Land Contamination

Environment Agency, 2009a SR2 Human Health toxicological assessment of contaminants in soil SC050021/SR2 (January 2009)

Environment Agency, 2009b SR3 Updated technical background to the CLEA model SC050021/SR3 (January 2009)

Scottish Environmental Protection Agency (SEPA) 2009 www.sepa.org.uk (Accessed throughout November 2009)

Eurocode 7 (2007) Geotechnical Design –BS EN 1997-2:2007

LQM/CIEH (2007) Generic Assessment Criteria for Human Health Risk Assessment. Land Quality Management Ltd and Chartered Institute of Environmental Health

Multimap (2009) www.multimap.co.uk (Accessed throughout November 2009)

Ordnance Survey (2009) www.ordnancesurvey.co.uk (Accessed throughout November 2009)

Planning Policy Statement 25 (PPS25): Development and Flood Risk. December 2006

ST. AMBROSE

Ground Contamination Risk Assessment

Report

for

Balfour Beatty

NOVEMBER 2009

Project No.: 5311


12/13 St. Andrew Square,Edinburgh. EH2 2AF

tel 0131 550 4070fax 0131 550 4093

[email protected]

murray.dobson

Sticky Note

The thickness and distribution of clay and silt and peat deposits has not been considered or demonstrated to be sufficient to reduce the likelihood of vertical migration of contaminants

Ground Contamination Risk

Assessment Report

ST. AMBROSE

Balfour Beatty

Revision History

Rev Date Purpose/Status Document Ref. Comments

1A 26th November 09 Final 5311.E.GQRA.1A For Issue

Author: Checked by: Approved by:

Environmental Engineer Senior Environmental Consultant Director



EXECUTIVE SUMMARY SCOPE

Purpose of the report


The proposed development will comprise the construction of St. Ambrose High School including a two-storey school building with associated school pitches, car parking, play areas and soft landscaping.

SITE INFORMATION

Grid Reference 271546, 665970 Site Area (approx.) 13.5ha

Current Site Description

Currently the site is occupied by numerous sports pitches to the south of Townhead Road and is in use by the general public as a recreational area. An area of car parking and an access road is present in the northeast of the site.

History

Until the 1980s, the site was used as rough pasture in a mining area with a railway crossing the north of the site and the eastern site boundary and coal pits to the northeast and southeast of the site. During the 1980s, the railway in the north was dismantled and a mineral railway was constructed across the southern area of the site.

The site was then used as a landfill from 1945-1972. By the 1990s the site was in use as playing fields following reprofiled and has remained so up to the present day. No further details are available regarding the capping of the landfill and development of the playing fields.

SITE INVESTIGATION

Previous SI A preliminary and main intrusive investigation were undertaken on site by URS in 2006 and 2008 respectively.

Activities

The supplementary site investigation works designed by Ramboll to address data gaps comprised 11No. mechanically-excavated trial pits to a maximum depth of 4.10mbgl, 11No. hand-excavated pits to a maximum depth of 1.20mbgl and soil sampling for chemical analysis.

Laboratory Analysis

37No. soil samples (including one duplicate) and 8No. leachate samples were analysed for a typical chemical suite including: pH, selected metals and inorganics, extractable petroleum hydrocarbons (EPH), polycyclic aromatic hydrocarbons (PAHs), phenols and an asbestos screen. Specific samples were also scheduled for foc, speciated hydrocarbons, volatile organic compounds and semi-volatile organic compounds.

GROUND CONDITIONS

Geology

Made Ground was encountered across the site comprising topsoil, reworked topsoil material and probable landfill material. The Made Ground ranges in thickness between 0.30m and 6.00m. The greatest depths of Made Ground were typically reported in the northern area of the site.

Superficial deposits of peat and glacial deposits of clay, sand and silt were encountered underlying Made Ground strata.

The solid geology of the Middle Coal Measures, described as interbedded sandstone, mudstone and coal was encountered at depths of between 6.50-23.20mbgl and was recovered as highly weathered sandstone.

Hydrology & Hydrogeology

Groundwater was typically recorded at the superficial to solid interface at depths ranging from 12.80 to 23.20mbgl. It is understood that this is the underlying aquifer. Perched shallow groundwater was also reported across the site within the Made Ground and superficial deposits, although typically, perched groundwater was reported above the peat at depths ranging from 1.90 to 4.70mbgl.

There are various drains labelled on the site plan located southwest of the site with Drumpellier Country Park, the nearest being approximately 10m from the southwest site boundary. On investigation, these are surface ditches, typically dry, which are likely to fill with water during heavy rain. The nearest surface water receptor is therefore Monkland Canal, which runs east to west and lies approximately 350m south of the site and Lochend Loch and Woodend Loch lie approximately 450m west and 650m northwest of the site boundary respectively.

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37 No. soil samples. Site is 13 Hectares. This equates to approximately 3 soil samples per hectare. Note that this is a supplementary investigation which proposes to assess previous data

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surface ditches - Question are these surface ditches discharging to surface water receptors, groundwater or sewer. Relevant to CSM



GROUND CONTAMINATION

Human Health

The risks to Human Health via direct contact with lead and nickel in localised areas across the site are considered to be LOW / MODERATE as these materials are at depths proposed to be excavated as part of the cut and fill works.

Localised elevated concentrations of PAHs are located in areas of proposed fill where there will be at least 600mm of fill and existing material located above the source strata. Therefore, these localised impacts are unlikely to present a significant risk via direct contact pathways. Risks to Human Health from these impacts are therefore considered to be LOW.

Risks to human health caused by elevated benzo(a)pyrene in probable landfill and topsoil material across the site and elevated benzo(a)anthracene in topsoil are considered likely to be significant in areas of soft landscaping where there may be an active direct contact pathway. Therefore, the risk to human health from benzo(a)pyrene and benzo(a)anthracene in soft landscaped areas is classified as MODERATE.

Controlled Waters

Risks to the Secondary Aquifer underlying the site are classified as LOW / MODERATE due to the impacts of manganese, ammonia and PAH reported within the shallow groundwater. Risks to the underlying aquifer from the localised hydrocarbons and marginal impacts of copper and zinc within the shallow groundwater are classified as LOW. Due to the significant depths of impermeable deposits including peat and clay overlying the aquifer in the majority of locations across the site it is considered unlikely that significant vertical migration of contaminants will occur.


The development proposals include increasing the area of hardstanding across the site thus reducing leaching potential and likely pathways through the landfill material. Based on the significant distance to the nearest surface water receptor (Monkland Canal; Lochend and Woodend Lochs all >350m from the site) and the proposed development minimising pollutant linkages, the risks to the surface water receptors are considered to be LOW.

Ground Gas

Ground gas monitoring visits were undertaken by URS in 2006 and 2008/9. The concentrations reported would classify the proposed development as Characteristic Situation 4 and appropriate ground gas protections measures will be required in the proposed development in accordance with CIRIA 665 (2007) and BS8485 (2008).

RECOMMENDATIONS

Further Assessment

• A Human Health Detailed Quantitative Risk Assessment (DQRA) is recommended in order to further assess the potential risks caused by site-wide impacts of benzo(a)anthracene in topsoil and benzo(a)pyrene in topsoil and landfill material.

Remedial Measures Required

• Ground gas protection measures will be required in the proposed development in accordance with Characteristic Situation 4 (CIRIA C665). A design for these protection measures has been proposed.

• Hotspots of lead and nickel have been identified in areas proposed to be excavated as part of the cut and fill works. During enabling works it is recommended that this material is stockpiled separately and subjected to validation testing to establish whether the material is suitable for use.

Additional Considerations

It is recommended that a suitably qualified Environmental Consultant is on site during the enabling works to ensure that should any areas of apparent contamination be exposed; the material is excavated, stockpiled separately onsite and subjected to validation testing in order to ensure the material is suitable for use. Allowances are also recommended to be made for the removal, treatment and disposal of shallow groundwater should dewatering be required during excavation.

An Environmental Specification Report is recommended to ensure the Contractor is undertaking all enabling works in accordance with the recommendations made in this report. A Validation Report will also be required to demonstrate that the enabling works have been carried out according to the Environmental Specification.

Laying underground services in potentially contaminated Made Ground materials has the potential to establish preferential flow pathways and therefore materials should be used appropriate to the level of contamination identified on site, particularly with regard to underground mains water supply. Consultation with Scottish Water is advised.

The site has been historically redeveloped and used as a landfill, and although not encountered during the site investigations, localised deposits of asbestos-containing materials have the potential to be present in Made Ground across the site. Appropriate health and safety precautions (i.e., provision of appropriate PPE to site development workers, etc.) should be adopted during enabling works.

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Secondary Aquifer - What is Ramboll's definition of this term?

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proposed soakaways. NB requirement for soakaways/infiltration is stricter than straightforward land contamination.

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the risks to the surface water receptors - assessment appears to be entirely qualitative

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considered unlikely that significant vertical migration - Appears that risk assessment is entirely qualitative



CONTENTS

EXECUTIVE SUMMARY 1

CONTENTS 1

1 INTRODUCTION 3

1.1 BRIEF 3 1.2 BACKGROUND 3 1.3 OBJECTIVES 3 1.4 CONSTRAINTS AND LIMITATIONS 4

2 SITE SETTING 5

2.1 SITE DESCRIPTION 5 2.2 SITE HISTORY 5 2.3 GEOLOGY 5 2.4 HYDROGEOLOGY & HYDROLOGY 6 2.5 FLOOD RISK 6 2.6 GROUND GAS 6 2.7 PREVIOUS GROUND INVESTIGATIONS 7 2.8 PRELIMINARY CONCEPTUAL MODEL 7

3 SITE INVESTIGATION 10

3.1 DESIGN 10 3.2 SITE INVESTIGATION ACTIVITIES 10 3.3 LIMITATIONS 10 3.4 LABORATORY CHEMICAL ANALYSIS 11

4 GROUND CONDITIONS 13

4.1 GENERAL STRATIGRAPHY 13 4.2 VISUAL AND OLFACTORY OBSERVATIONS OF POTENTIAL CONTAMINATION 14 4.3 GROUNDWATER OCCURRENCE 15

5 GROUND CONTAMINATION ASSESSMENT 16

5.1 HUMAN HEALTH ASSESSMENT 16 5.2 CONTROLLED WATERS ASSESSMENT 20 5.3 GROUND GAS RISK ASSESSMENT 28

6 GROUND CONTAMINATION 31

6.1 CONCEPTUAL SITE MODEL 31 6.2 QUALITATIVE RISK ASSESSMENT 33 6.3 DEVELOPMENT CONSIDERATIONS 36

7 RISK MANAGEMENT STRATEGY 38

7.1 SIGNIFICANT POLLUTANT LINKAGES 38 7.2 RECOMMENDATIONS 38 7.3 ADDITIONAL CONSIDERATIONS FOR DEVELOPMENT 39

8 REFERENCES 41



APPENDICES

APPENDIX A DRAWINGS AND FIGURES

DRAWING 5311/E/001 EXPLORATORY HOLE LOCATION PLAN

DRAWING 5311/E/002 PROPOSED DEVELOPMENT PLAN (SITE LAYOUT)

DRAWING 5311/E/003 CURRENT SITE LAYOUT PLAN (EXISTING SITE LEVELS)

DRAWING 5311/E/004 CONCEPTUAL SITE MODEL (CROSS SECTION)

FIGURE 2.1 SITE LOCATION PLAN

FIGURE 2.2 PHOTOGRAPHS OF DRAINS ADJACENT TO SITE

APPENDIX B CORRESPONDENCE WITH NORTH LANARKSHIRE COUNCIL / WSP

APPENDIX C GROUND CONTAMINATION ASSESSMENT; CONTEXT AND METHODOLOGIES

APPENDIX D EXPLORATORY HOLE LOGS FROM SUPPLEMENTARY SITE INVESTIGATION (RUK)

APPENDIX E CHEMICAL LABORATORY RESULTS FROM SUPPLEMENTARY SITE INVESTIGATION (RUK)

APPENDIX F EXPLORATORY HOLE LOGS AND CHEMICAL ANALYSIS FROM PREVIOUS INVESTIGATION (URS, 2006)

APPENDIX G EXPLORATORY HOLE LOGS AND CHEMICAL ANALYSIS FROM PREVIOUS INVESTIGATION (URS, 2008)

APPENDIX H CHEMICAL SCREENING TABLES

APPENDIX I CORRESPONDENCE TO COUNCIL FROM URS REGARDING GROUND GAS (MAY 2009)

APPENDIX J GROUND GAS MONITORING RESULTS (URS 2006; 2008/9)

APPENDIX K GROUND GAS PROTECTION SYSTEM PROPOSAL (LANDLINE)

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5311/E/001 EXPLORATORY HOLE LOCATION PLAN. What is the red outline shown on this plan? There are investigation locations outside this line and the number of locations is limited in the south (TP3, TP4, TP5)



1 INTRODUCTION

1.1 Brief


This report provides a factual summary of the supplementary investigation and an assessment of ground contamination risks based on all available data.

The proposed development will comprise the construction of St. Ambrose High School including a two-storey school building with associated school pitches, car parking, play areas and soft landscaping. The current proposed development plan is provided as Drawing 5311/E/002, Appendix A.

1.2 Background

Ramboll UK understand 1No. desk study (Phase I) and 2No. intrusive site investigations (Phase II) have been undertaken within the site boundary since 2005; available reports and investigations for the site are outlined below:


- Preliminary Ground Investigation Report, St. Ambrose High School, Coatbridge (URS, 2006);

- Proposed St. Ambrose High School, Ground Investigation Report (URS, 2008); and


A review of these reports was undertaken by WSP (2009) on behalf of North Lanarkshire Council’s Environmental Department and is detailed in the letters outlined below and provided in Appendix B:

- Report Review – Proposed St. Ambrose High School, WSP 17th November 2008;

- Proposed St. Ambrose, Townhead Report Review Summary and Recommendations, Environmental Services 18th November 2008 (incl. URS response to comments); and


The additional investigation works undertaken by Ramboll and detailed in this report are to supplement the existing site data and provide additional information across the site. This data will inform a full, robust environmental risk assessment for the proposed St. Ambrose School and address the concerns raised by WSP (2009).

1.3 Objectives

The objectives of the supplementary site investigation works and report were to further establish the environmental ground conditions in the area of the proposed soakaways, undertake additional shallow soil analysis to address data gaps within the URS report in order to fully address the risks to Human Health and provide a Ground Contamination Risk Assessment for the proposed development using all available data and address the concerns raised by WSP (2009).

In order to achieve these objectives the following scope of works were undertaken:

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Ramboll UK understand 1No. desk study (Phase I) and 2No. intrusive site investigations (Phase II) have been undertaken within the site boundary since 2005; available reports and investigations for the site are outlined below: - St. Ambrose High Desk Study (URS, 2005); - Preliminary Ground Investigation Report, St. Ambrose High School, Coatbridge (URS, 2006); - Proposed St. Ambrose High School, Ground Investigation Report (URS, 2008); and - Proposed St. Ambrose High School, Additional Gas Monitoring (URS, 2009) A review of these reports was undertaken by WSP (2009) on behalf of North Lanarkshire Council’s Environmental Department and is detailed in the letters outlined below and provided in Appendix B: - Report Review – Proposed St. Ambrose High School, WSP 17th November 2008; - Proposed St. Ambrose, Townhead Report Review Summary and Recommendations, Environmental Services 18th November 2008 (incl. URS response to comments); and - Report Review Follow Up – St. Ambrose High School, WSP 31st August 2009. The additional investigation works undertaken by Ramboll and detailed in this report are to supplement the existing site data and provide additional information across the site. This data will inform a full, robust environmental risk assessment for the proposed St. Ambrose School and address the concerns raised by WSP (2009). Note - the letter from WSP is included as appendix in hard copy. We have not been provided with the previous reports. Section 1.3 indicates that this previous data has been incorporated into the risk assessments undertaken



• Site investigation comprising:

- 5No. machine-excavated trial pits to a maximum depth of 3.30mbgl (below ground level) in the areas of the proposed soakaways;

- 6No. machine-excavated trial pits to a maximum depth of 4.10mbgl across the site;

- 11No. hand excavated pits to a maximum depth of 1.20mbgl across the site;

- Soil sampling for chemical laboratory analysis; and

• Factual and interpretative reporting comprising:

- Generic quantitative risk assessment using both new and existing data to characterise contamination risks associated with the proposed development;

- Qualitative risk assessment to identify potentially significant ground contamination risks associated with the proposed development and also with regard to the construction phase of the works; and

- Development of a risk management strategy outlining significant ground contamination risks and recommendations for their mitigation.

All ground contamination assessment work has been completed in accordance with the current UK legislative framework, further details of which are provided in Appendix C.


This report has been prepared for the exclusive use of the Balfour Beatty for the purpose of assisting site evaluation in the context of the proposed redevelopment at the time of writing. This report should not be used in whole or in part by any third parties without the express permission of Ramboll UK Ltd. in writing.

Ramboll has endeavoured to assess all information provided to them during this appraisal. This report summarises information provided from a number of external sources and cannot offer any guarantees or warranties for the completeness or accuracy of information relied upon.



2 SITE SETTING

The site of the proposed St. Ambrose High School is located in Coatbridge, Lanarkshire. A site location plan is presented as Figure 2.1 in Appendix A.


The site is located off Townhead Road and is bordered by Townhead Road to the north, a community centre, pavilion and residential properties to the east, Drumpellier Park to the south and a Golf Course to the west.

The site is located at the approximate National Grid Reference (NGR) 271546, 665970 and occupies an area of approximately 13.5Ha. Currently the site is occupied by numerous sports pitches and is in use by the general public as a recreational area. An area of car parking and an access road is present in the northeast of the site. A current site layout plan indicating current topographic levels is included in Appendix A as Drawing 5311/E/003.

2.2 Site History

This summary of the site history has been compiled using the available Ground Investigation Reports (URS, 2006; 2008). According to this information, the site remained in use as rough pasture in a mining area with a railway crossing the north of the site and the eastern site boundary and coal pits to the northeast and southeast of the site until the 1890s when the railway in the north was dismantled and a mineral railway was constructed across the southern area of the site.

By 1912 a reservoir was present to the southeast of the site boundary and 2No. tanks were located northeast of the site. Residential developments were constructed to the north of the site by the 1930s and the railway was dismantled.

The site was then used as a landfill from 1945-1972. Information obtained from North Lanarkshire Council indicate that Townhead Landfill received an estimated half million tonnes of domestic refuge from Coatbridge and 77,000 gallons of wet sewage and unspecified residue from Gartsherrie Steel Works were disposed of annually for an unknown period of time. By the 1990s the site was in use as playing fields following remodelling and has remained so up to the present day. No further details are available regarding the capping of the landfill and development of the playing fields.

2.3 Geology

Based on the information obtained from previous site investigations (URS, 2006; 2008); the geology underlying the site is understood to comprise Made Ground including topsoil overlying probable landfill material up to a maximum depth of 8.45mbgl. No significant capping layer is present above the probable landfill material. Underlying the Made Ground are superficial deposits of peat, glaciolacustrine clay, silt and sand and glacial till to a maximum depth of 23.2mbgl. These superficial deposits overlie the solid geology of the Middle Coal Measures, reported at depths between 7.40mbgl and 23.20mbgl and comprise sandstone and mudstone with occasional bands of coal.

The site is underlain by several coal seams, some of which have been historically mined by shallow workings. In addition, mine shafts have been identified in and



around the site. The potential geotechnical risks from mining instabilities are not discussed further in this report.

2.4 Hydrogeology & Hydrology

The previous investigations (URS, 2006; 2008) indicate that the solid geology underlying the site is classified as moderately permeable according to the Scottish Environmental Protection Agency (SEPA). This is comparable to the Environment Agency (EA) classification of a Secondary Aquifer. The site is not within a source protection zone.

During the URS investigations in 2006 and 2008, groundwater was typically recorded at the superficial to solid interface at depths ranging from 12.80 to 23.20mbgl. It is understood that this is the underlying aquifer. Perched shallow groundwater was also reported across the site within the Made Ground and superficial deposits, although typically, perched groundwater was reported above the peat at depths ranging from 1.90 to 4.70mbgl.

There are various drains labelled on the site plan located southwest of the site with Drumpellier Country Park, the nearest being approximately 10m from the southwest site boundary. On investigation, these are surface ditches, typically dry, which are likely to fill with water during heavy rain. A photograph is included in Appendix A as Figure 2.2. The nearest surface water receptor is therefore Monkland Canal, which runs east to west and lies approximately 350m south of the site and Lochend Loch and Woodend Loch lie approximately 450m west and 650m northwest of the site boundary respectively.

2.5 Flood Risk

The Scottish Environmental Protection Agency’s indicative floodplain map shows that the site does not lie within an area of potential risk from river or sea flooding. The nearest area in the vicinity of the site at risk of flooding lies approximately 150m northeast of the site boundary.

2.6 Ground Gas

There is a potential for the build up of potentially hazardous ground gas across the site. The site has previously been used as a landfill and there is a layer of peat across the majority of the site; both of which have the potential to generate potentially hazardous ground gases. In addition, the site is in an area associated with mining and therefore there is a potential for potentially hazardous mine gases to be generated. The source of the very high methane concentrations is the natural peat deposits underlying the site

Due to the potential risks from ground gas in the context of the proposed development, 4No. ground gas monitoring visits were undertaken as part of the initial investigation (URS, 2006) between August and October 2006. Maximum concentrations of 12.6% carbon dioxide, 4.0% methane and a maximum flow rate of 2.5l/hr was recorded during these monitoring visits.

An additional 4No. rounds of monitoring were undertaken following the URS investigation (2008) during August 2008 and maximum concentrations of 30.2% carbon dioxide, 68.7% methane and a negligible flow rate were recorded during these monitoring visits. It is considered unlikely that no flow rate would occur across

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surface ditches - Appear to drain to Lochend Loch to the northwest. Would be pathways to surface water receptors. and groundwater infiltration.

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Section 2.4 of The report states that the site is not within a source protection zone. This comment is incorrect. All groundwater in Scotland is designated a drinking water protected area for groundwater. SEPA records indicate that there is no data on drift aquifer and the bedrock aquifer is intergranular Fractures Moderately (IFM) productive Aquifer being given Vulnerability class 1 (least vulnerable) The term Secondary aquifer is not relevant to SEPA classification of aquifers

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URS investigations: the summary data for this monitoring should be presented and where possible groundwater contours drawn.

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Secondary Aquifer. The term secondary aquifer is not used by SEPA.



the site during all 4No. monitoring rounds therefore the negligible flow rates reported during these visits are considered to be invalid.

An additional 12No. rounds of monitoring were carried out between November 2008 and April 2009. Maximum concentrations of 32.2% carbon dioxide, 75.4% methane and a maximum flow rate of 10.9l/hr were recorded during these monitoring visits.

Based on current guidance, these results would classify the site as Characteristic Situation 4. However, URS argued that the high flow rate reported (10.9l/hr) was a spurious result as it only occurred once, from one borehole and therefore the next highest flow rate reported (1.8l/hr) should be used when classifying the gas regime on the site. Using this flow rate, the site would be classified as Characteristic Situation 3.

This classification was not deemed appropriate by the Environmental Services Department at North Lanarkshire Council as they considered the 10.9l/hr flow rate reported was a valid result and therefore should be incorporated into the ground gas assessment. Therefore the gas regime on site is considered to be representative of Characteristic Situation 4 and appropriate protection measures should be incorporated into the proposed development.

2.7 Previous Ground Investigations

Site investigations were undertaken on site by URS in 2006 and 2008 and interpretation of geoenvironmental ground conditions was provided by URS in 2008. Data from these investigations has been incorporated into this report to inform a full, robust assessment of the potential risks to Human Health and Controlled Waters that may exist on site based on the proposed development.

The preliminary investigation in 2006 comprised:

• 10No. machine-excavated trial pits to depths of 2.30-4.90mbgl; • 7No. cable percussive boreholes to depths of 5.00-11.50mbgl; • 4No. rotary boreholes to depths of 26.70-39.00mbgl; • 4No. rounds of ground gas monitoring; • Geotechnical and environmental sampling and analysis; and • Factual Reporting.

The main investigation in 2008 comprised:

• 17No. cable percussive boreholes to depths of 7.05-15.50mbgl; • 10No. rotary boreholes to depths of 39.40-47.30mbgl; • 105No. machine-excavated trial pits to depths of 2.00-4.30mbgl; • Geotechnical and environmental sampling and analysis; • 1No. round of groundwater monitoring and sampling; • 4No. rounds of ground gas monitoring; and • Factual and Interpretative Reporting

A plan illustrating all the exploratory hole locations is included in Appendix A as Drawing 5311/E/001.

2.8 Preliminary Conceptual Model

Risk from contamination is assessed by consideration of possible linkages between contaminant sources and potential receptors which could be harmed or polluted. The key aspect of the UK contaminated land framework is the development of a



conceptual model which illustrates the spatial interaction between the potential sources and receptors on site. Sources, receptors and pathways are defined as:

• A source, i.e., a substance that is capable of causing pollution or harm; • A pathway, i.e. a route by which the contaminant can reach the receptor; and • A receptor (or target), i.e. something which could be adversely affected by

the contaminant.

Further details of the current UK contaminated land framework for contamination assessment are provided in Appendix C.

2.8.1 Sources

A review of historical and current land use on site and in the surrounding area has been undertaken. Potential contamination sources and actual sources of contamination (as identified in the previous site investigations) are summarised below:

Table 2-1: Potential/actual sources of contamination

Source Potential/actual

contaminant and/or hazard

Description/properties

Made Ground

(Landfill)

Heavy metals, Polycyclic Aromatic Hydrocarbons (PAHs), hydrocarbons,

Volatile Organic Compounds (VOCs) Semi-Volatile Organic Compounds

(SVOCs), asbestos and ground gas

Elevated concentrations of various contaminants including lead, nickel, arsenic, cyanide, chromium, benzo(a)pyrene, dibenzo(a,h)anthracene and aromatic EC21-35 hydrocarbons were identified in isolated areas of Made Ground across the site. This material is also known to be generating potentially hazardous ground gases.


Mining including railways

Heavy metals, inorganics, hydrocarbons, PAHs,

asbestos and ground gas

Elevated concentrations of various contaminants including lead, nickel, arsenic, cyanide, chromium, benzo(a)pyrene, dibenzo(a,h)anthracene and aromatic EC21-35 hydrocarbons were identified in isolated areas of Made Ground across the site. Some of these contaminants may have been generated as a result of the mining activities on site.

In addition potentially hazardous ground gases may be generated from the coal seams and former mining activities on site.


Peat Ground Gas Peat underlies the majority of the site and is known to be generating potentially hazardous ground gases.

2.8.2 Pathways

In order for contaminants to reach potential receptors, there has to be a viable route for the contaminant. Potential pathways considered given the nature of the proposed development and the potential contaminative sources identified:

• Dermal contact with soils; • Ingestion of soils; • Inhalation of dust and vapours; • Plant root up-take;

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2.8.2 Pathways. The surface water drains are not identified as pathways. The fact that they are only sporadic is not sufficient to exclude them as potential contaminant pathways. the likely input from contaminants will be dependant on the geological relationship between groundwater and these drains. The fact that they are sporadic suggests limited opportunity for lateral groundwater migration



• Migration of ground gases; and • Leaching and subsequent migration of groundwater.

2.8.3 Receptors

The site-specific receptors that could potentially be affected by the hazards identified in relation to the current and future use of the site for a school with areas of soft landscaping:

Human Health

• Current and future site users; and • Site development workers.

Environmental

• Moderately Permeable Aquifer (Middle Coal Measures); • Monkland Canal approximately 350m south of the site boundary; • Structures and services; • Adjacent properties; and • Plants and vegetation.

2.8.4 Summary

The most significant potential pollutant linkages identified are:

• Direct contact with potentially contaminated Made Ground soils by future site users and construction workers;

• Leaching of contaminants into underlying groundwater and subsequent vertical migration into the underlying aquifer or lateral migration into surface water receptors;

• Migration and accumulation of potentially hazardous ground gases in confined spaces resulting in asphyxiation or explosion; and

• Inhalation of airborne dust or fibres associated with demolition material within the Made Ground.

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2.8.3 Receptors Environmental. The Monkland canal is picked out as a receptor, the Lochend Loch has not been identified as a Receptor. The surface water drainage ditches appear to drain towards this feature rather than the Monkland canal.

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potential pollutant linkages. Lateral migration in surface water surface water channels. Would not be an issue if there was no surface contamination to leach or the water did not infiltrate and then run into drains.

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Leaching and subsequent migration of groundwater is identified as a pathway. no mention is made of the presence of preferential flow paths in the form of mine shafts.



3 SITE INVESTIGATION

3.1 Design

The site investigation was designed as a supplementary investigation in order to supplement the existing site data and provide a full assessment of the nature and extent of any ground contamination on site, addressing the concerns raised by WSP (2009). The investigation was undertaken and supervised by Geotechnics Ltd. on behalf of Ramboll UK and exploratory hole logs were produced by a Ramboll Environmental Consultant and logged in accordance with BS 5930.

The objectives of the supplementary site investigation were as follows:

• Identify any potential contaminants and their potential leaching capacity across the site that may be associated with former land-use in areas not previously investigated;

• To provide additional environmental information about the topsoil and shallow Made Ground material across the site;

• Identify any potential contaminants and their potential leaching capacity in the areas of the proposed soakaways; and

• Provide additional information on shallow environmental ground conditions across the whole of the site.

3.2 Site Investigation Activities

The supplementary site works were carried out on the 24th September and the 1st-2nd October 2009 by Geotechnics Ltd. The investigation comprised the following scope of works:

• 5No. machine-excavated trial pits to a maximum depth of 3.30mbgl (below ground level) in the areas of the proposed Soakaway;

• 6No. machine-excavated trial pits to a maximum depth of 4.10mbgl across the site;

• 11No. hand excavated pits to a maximum depth of 1.20mbgl across the site; and

• Soil sampling for chemical laboratory analysis.

The locations of the exploratory holes are shown on Drawing 5311/E/001 in Appendix A. Exploratory hole logs are presented in Appendix D, and laboratory chemical analysis results are presented in Appendix E.

3.3 Limitations

Various limitations were experienced whilst undertaking the site investigation. These included the following:

• The machine-excavated trial pits had to be located outside of the current playing fields to avoid any damage as these pitches are still in use by the general public.

It should be noted that although every effort has been made to ensure the accuracy of the data obtained from the investigation, the possibility exists for variations in ground and groundwater conditions between and around exploratory hole locations. In addition, groundwater levels are likely to vary seasonally and with changes in



weather conditions.

3.4 Laboratory Chemical Analysis

A total of 71No. soil samples were despatched to the Derwent Environmental Testing Services (DETS) laboratory in County Durham. DETS is a UKAS and MCERTS accredited laboratory.

37No. soil samples (plus 1No. duplicate) were scheduled by Ramboll UK for chemical analysis, including the following suite of determinands based on historical site use, the findings of previous site investigations, guidance given in the DoE Industry Profiles and CLR8, and on professional experience:

• Speciated Polycyclic Aromatic Hydrocarbons (PAH) (US EPA priority PAHs); • Extractable Petroleum Hydrocarbons (EPH); • Metals (arsenic, cadmium, chromium, copper, nickel, lead, zinc, mercury,

boron and selenium); • Sulphide, Sulphate and Sulphur; • pH; and • asbestos in Made Ground strata.

In addition, 8No. soil samples were scheduled for analysis of fraction of organic carbon (foc), 10No. samples were scheduled for speciated Total Petroleum Hydrocarbon (TPH) analysis and 2No. samples were scheduled for Volatile Organic Compound (VOC) and Semi Volatile Organic Compound (SVOC) analysis.

18No. soil samples were also scheduled for leachate analysis, for the suite of determinands as detailed below:

• Metals, Cyanide, pH, Sulphate and Sulphide; • Phenols; • Hardness as CaCO3; • PAHs (USEPA 16No. priority Polycyclic Aromatic Hydrocarbons); and • Extractable Petroleum Hydrocarbons (EPH).

Laboratory chemical analytical results are presented in Appendix E.

3.4.1 Quality Assurance/Quality Control analysis

Duplicate soil sampling results are illustrated in Table 3-1:

Table 3-1: Comparison of Duplicate Soil Sample Analyses

Determinand HDP11

(mg/kg) D1

(mg/kg)

Arsenic 17 17

Cadmium 1.8 2

Chromium 32 57

Chromium (Hexavalent) < 1 < 1

Copper 200 290

Lead 580 480

Mercury 0.14 0.14

Nickel 120 150

Selenium 0.9 0.9

Zinc 620 600



Determinand HDP11

(mg/kg) D1

(mg/kg)

Boron 2.7 2.5

Sulphate (Total) 0.17 0.11

Sulphur (Total) 0.12 0.09

Sulphide 48 44

pH 7.6 7.5

EPH 620 670

Acenaphthene < 0.1 0.3

Acenaphthylene < 0.1 < 0.1

Anthracene 0.4 0.7

Benzo(a)anthracene 0.7 0.9

Benzo(a)pyrene 0.9 0.9

Benzo(b)fluoranthene 0.3 0.3

Benzo(k)fluoranthene < 0.1 < 0.1

Benzo(g,h,i)perylene 0.4 0.5

Chrysene 0.7 0.9

Dibenzo(a,h)anthracene < 0.1 < 0.1

Fluoranthene 0.8 0.9

Fluorene < 0.1 0.4

Indeno(1,2,3-c,d)pyrene 0.4 0.7

Naphthalene < 0.1 < 0.1

Phenanthrene 0.8 1.6

Pyrene 1 1.1

PAH 6.5 9.2

Duplicate sample analysis is used to provide an indication of the precision of the analytical results, i.e., the repeatability of the laboratory analytical process. The results of the duplicate analyses are compared with the original sample data. If the results of the sample and duplicate analyses are similar (i.e., within ±30%), it is generally considered that an acceptable standard of repeatability has been maintained in the sampling and analytical process, and that the results can therefore be described as being precise. Only PAH results show a discrepancy of >30% likely due to variations in coal and clinker identified in this location. Considering the remainder of results are within ±30% results are considered precise.



4 GROUND CONDITIONS

4.1 General Stratigraphy

Reference has been made to the supplementary investigation recently undertaken by Geotechnics Ltd. and previous investigations undertaken by URS (2006; 2008). Exploratory hole logs and chemical analysis data from the URS investigation (2006) are presented in Appendix F and data from the URS investigation (2008) are presented in Appendix G for reference.

Exploratory hole logs from the supplementary investigation and logged by Ramboll UK (to BS5930) are presented in Appendix D. An Exploratory Hole Location Plan is included as Drawing No. 5311/E/001 in Appendix A.

The ground conditions encountered during the site investigation works are summarised in Table 4-1 below. Only the dominant soil types are included and summary descriptions have been used:

Table 4-1: Stratigraphic Succession


encountered (mbgl)

Depth to base

(mbgl)

Maximum thickness

(m)

Made Ground (Topsoil)

Silty Sand/Sandy Silt (dark brown silty fine sand and sandy silt with frequent rootlets and occasional gravel).

0.00 0.00-0.60 0.60

Made Ground (Reworked Topsoil)

Sandy Gravelly Silt (dark brown slightly gravelly sandy silt. Gravel is subangular to subrounded fine to coarse of coal, clinker, sandstone, glass and other minor constituents. Sand is fine to medium) 0.05 0.10-0.50 0.30

Silty Sand (dark brown silty fine to medium sand)

Made Ground (Probable Landfill)

Sandy Gravel (red-brown to brown-grey sandy angular to rounded fine to coarse gravel of ash, sandstone, burnt shale, coal, glass, bottles and jars, porcelain, newspaper, slag, wood and numerous other minor constituents depending on location.)

0.00 0.90-6.101

6.00 Gravelly Sand (red-brown to brown-grey gravelly fine to coarse sand. Gravel is angular to rounded fine to coarse gravel of ash, sandstone, burnt shale, coal, glass, bottles and jars, porcelain, newspaper, slag, wood and numerous other minor constituents depending on location.)

Superficial Deposits

Peat (Soft brown to red-brown spongy to amorphous fibrous peat.)

1.40 3.50-9.60 5.50

Sandy Gravelly Clay (soft to stiff brown to grey gravelly sandy clay. Sand is fine. Gravel is angular to rounded fine to coarse of sandstone, shale, coal, charcoal and quartzite.)

0.00 3.00-23.20

23.20

Gravelly Sand (grey to orange-brown silty slightly gravelly fine to medium sand. Gravel is subangular to rounded fine to coarse of sandstone and charcoal.)

2.90 3.10-11.90

2.35

Silt (very soft to firm grey and brown sandy silt. Sand is fine.) 4.00

7.10-13.70

4.20




encountered (mbgl)

Depth to base

(mbgl)

Maximum thickness

(m)

Middle Coal Measures (interbedded sandstone, mudstone and coal)

Sandstone (moderately strong to strong light grey to white fine to coarse grained sandstone with occasional mudstone laminations.)

6.5-23.20 Not

proven Not

proven

Mudstone (laminated dark grey mudstone with occasional carbonaceous laminations and plant fossils.)

7.4-25.25 Not

proven Not

proven

Coal (Moderately weak to weak dark grey coal with occasional laminations of carbonaceous mudstone.)

23.30-25.05 Not

proven Not

proven

1 Made Ground persists to a maximum of 10.80mbgl and 13.60mbgl in R04 and R03 (2006) respectively. This is described in drillers logs as “Made Ground (ash, peat and clay)” immediately overlying the bedrock. This description is considered likely to be a Driller’s combined description of the Made Ground and underlying superficial deposits and therefore has been omitted from this table.

4.2 Visual and Olfactory Observations of Potential Contamination

During the previous and supplementary site investigations, visual and olfactory observations of potential contamination were observed in a number of exploratory holes, as summarised in Table 4-2. Ash is not included in the table as it was commonly encountered as gravel in Made Ground.

Table 4-2: Visual and Olfactory Evidence of Potential Contamination


Contamination




TP1 (2006) 0.70-0.90 Made Ground: Light grey brown CLAY with small pockets of fibrous peat and coal.

TP101 (2009) 0.35-0.45 Made Ground: Dark brown to red-brown very gravelly fine to coarse SAND.

TP03 (2009) 2.30-3.00 Soft dark brown to dark grey slightly gravelly silty CLAY.


TP04 (2009) 1.50-2.40 Soft very dark brown occasionally mottled grey and black slightly sandy SILT/CLAY.

Moderate to heavily decomposed organic material (with moderate to strong rotting odour in TP102)


HDP07 (2009) 1.00-1.10 Made Ground: Dark brown to green-brown heavily decomposed organic material.



TP101 (2009) 0.80-2.90 Made Ground: Firm dark brown to grey-brown gravelly CLAY.

TP238 (2008) 3.40-4.10 Made Ground: Dark grey slightly clayey cobbly SAND and GRAVEL.

Slight hydrocarbon odour

TP102 (2009) 0.90-1.35 Made Ground: Firm dark brown very gravelly CLAY.

Slag 46No. exploratory



Clinker 22No. exploratory



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Sticky Note

Table 4.1. It would be useful to present this information as a series of cross sections and a rockhead contour plan may be useful to demonstrate the thickness of superficial deposits overlying bedrock

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Visual and Olfactory Evidence of Potential Contamination. Review of distribution of observations of visual and olfactory contamination suggests that the contamination is intermittent associated with localised hotspots within made ground material. (See 5311e001 hole location plan.pdf)




Contamination



Tarmacadam BH202 (2008) 0.05-0.70 Made Ground: Brown sandy gravelly CLAY.

Bitumen TP231 (2008) 2.90-3.90 Made Ground: Dark brown to grey clayey cobbly SAND and GRAVEL.

4.3 Groundwater Occurrence

Groundwater strikes were encountered typically at the interface between the superficial and solid geology at depths ranging from 10.80mbgl to 23.20mbgl. It is likely that this represents the underlying Secondary Aquifer.

Groundwater strikes were also encountered within the Made Ground across the site, perched over the peat at depths ranging from 1.50mbgl to 4.90mbgl.

Groundwater was also encountered in some of the gravelly clay and silt deposits in localised areas across the site at depths ranging from 2.80mbgl to 11.00mbgl.

No groundwater monitoring was undertaken as part of the supplementary investigation although groundwater monitoring was undertaken during the previous investigations. Wells were installed into the Made Ground and superficial deposits across the site at depths ranging from 0.50-11.50mbgl (URS, 2008). Groundwater was reported in these wells at depths between 1.61-4.91mbgl within Made Ground and between 2.45-8.14mbgl within the superficial deposits. See Section 2.4 for further details of the groundwater regime across the site.

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4.3 Groundwater Occurrence. While a useful summary, the groundwater levels have not been measured to ordnance datum and has not been presented as hydraulic contours. The summary strike data suggests possible perched groundwater within superficial deposits. The status of these superficial deposits and their potential to support a groundwater body has not been considered.

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No groundwater monitoring undertaken during this investigation. It is not possible form the information presented in this report to ascertain the depth to groundwater and the strata that groundwater is found in. Groundwater flow direction not established. (note that all readings are in mbgl)



5 GROUND CONTAMINATION ASSESSMENT

This ground contamination assessment has been undertaken in accordance with the current UK framework and comprises a generic quantitative risk assessment as defined in CLR 11. Further details of the legislative framework and CLR11 are provided in Appendix C.

In order to assess the significance of the chemical concentrations reported, generic assessment criteria (GAC) must be selected based on the critical receptors identified at the site. Receptors are considered in relation to Human Health (e.g., people using the site) and Controlled Waters (e.g., water resources).

Potential risks to Human Health from soil impacts are considered using the measured soil concentrations. Potential risks to Controlled Waters are considered using soil leachate concentrations as indicative of the potentially mobile fraction of any soil impact and also measured groundwater concentrations.

5.1 Human Health Assessment

5.1.1 Methodology

Details of the UK framework for human health risk assessment and GAC are provided in Appendix C. GAC are provided for 3 standard land uses only: residential, allotments and commercial.

The site is proposed to be redeveloped as a secondary school (for 11-18 yr olds), with associated playing fields, parking, play areas and soft landscaping. This site has therefore been classified for the purposes of the screening assessment as residential without home-grown produce according to current UK guidance.

Contaminant concentrations below the adopted GAC are considered not to warrant further risk assessment. Where any concentrations are recorded above the GAC consideration of the contaminant distribution is undertaken and statistical analysis used where appropriate.

5.1.2 Soil Screening Analysis

Chemical analysis screening summary tables are held in Appendix H, detailing the measured concentrations of potential contaminants in comparison with the applicable GAC for a residential land use based on current UK guidance (2009). These tables combine chemical data from the initial investigations in 2006 and 2008 (URS) with data from the recent supplementary investigation (RUK, 2009).

Measured concentrations above the recommended GAC are highlighted within the tables (Appendix H) and Table 5-1 provides a summary of these exceedences.

Table 5-1: Summary of Soil Exceedences Compared with Relevant GAC

Determinand GAC

(mg/kg)


No. of Exceedences

Maximum (mg/kg)

Arsenic 35 82 5 71

Lead 450 82 18 6600

Nickel 130 82 3 660

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5.0 Potential risks to Controlled Waters are considered using soil leachate concentrations as indicative of the potentially mobile fraction of any soil impact and also measured groundwater concentrations. Consideration of soil concentrations and simple partition coefficient calculations should also be undertaken.



Determinand GAC

(mg/kg)


No. of Exceedences

Maximum (mg/kg)

pH <5, >9

(pH units) 82 3 (<pH5) 4.53 (min)

Benzo(a)anthracene 6.2 79 5 14


Benzo(b)fluoranthene 7.4 79 1 9.3

Chrysene 10 79 1 11

Dibenzo(ah) anthracene

0.93 79 7 5.3

Indeno(1,2,3-c,d)pyrene

4.4 79 3 6.6

Aromatic C21-C35 1300 49 3 1900

EPH 1300* 35 4 6400

*GAC for Extractable Petroleum Hydrocarbons based on that for Aromatic >C21-C35, representing a conservative estimate of the typical hydrocarbon fraction likely to cause harm to human health.

The majority of exceedences detailed in Table 5-1 above are from Made Ground soils only including landfill, topsoil and reworked topsoil, with the following exceptions:

• Acid conditions and elevated hydrocarbons (aromatic C21-C35) concentrations in peat from BH210 (5.3mbgl), TP307 (2.2mbgl) and BH302 (3.3mbgl).

• Elevated EPH, benzo(a)pyrene and dibenzo(a,h)anthracene was reported at 2.8mbgl in the peat from TP01 (2009); and

• Elevated EPH was reported at 2.6mbgl in the organic-rich clay from TP03 (2009).

Asbestos None of the 46No. samples scheduled for asbestos analysis were found to contain asbestos-containing materials.

Volatile Organic Compounds (VOC) and Semi Volatile Organic Compounds (SVOCs) None of the 4No. samples scheduled for VOC and SVOC analysis were found to contain concentrations of any VOCs of SVOCs above the laboratory detection limit.

5.1.3 Soil Contaminant Distribution Assessment


Metals

Arsenic was reported as elevated in 5No. samples of Made Ground considered to be probable landfill material at depths ranging from 0.70mbgl to 5.00mbgl.

Lead was reported at elevated concentrations in 17No. samples of probable landfill material and 1No. sample of reworked topsoil at depths ranging from 0.30mbgl to 5.00mbgl. It is likely that these elevated concentrations are attributable to the ash reported in the probable landfill material reported in these locations and across the site.

Elevated concentrations of nickel were reported in 3No. samples of Made Ground considered to be landfill material at depths ranging from 2.00mbgl to 5.00mbgl.



pH

Acidic conditions ranging from pH 4.53 were reported in 3No. samples of peat from across the site at depths ranging from 2.20-5.30mbgl. Peat is naturally acidic and the pH of this stratum is typically lower than in other strata across the site. However, as the average pH for the peat across the site is 5.83 and within the recommended GAC range for the proposed development therefore there is not considered to be a significant risk from acidic conditions within the peat.

The pH recorded within the shallow soils was within the recommended GAC range for the proposed development.

Polycyclic Aromatic Hydrocarbons

Significantly elevated concentrations of a variety of Polycyclic Aromatic Hydrocarbons (PAHs) were reported in Made Ground (including topsoil and landfill material) from across the site and in 1No. sample of peat from across the site.

More significantly elevated concentrations of PAHs are reported within the topsoil and reworked topsoil and the elevated concentrations within the peat are of a different composition.

Hydrocarbons

Elevated hydrocarbon (EPH) concentrations were reported in 4No. samples. 1No. from probable landfill material in HDP05 at 1.00mbgl, 1No. from reworked topsoil in HDP07 at 0.25mbgl, 1No. from peat in TP01 at 2.80mbgl and the most significant from natural clay in TP03 at 2.60mbgl reported as having a slight organic odour. Speciated data was also obtained from this sample and the concentrations of total aliphatic/aromatic hydrocarbons C5-C35 amounts to 130mg/kg. Therefore, it is considered likely that the elevated hydrocarbons reported are within the heavy-end fraction of hydrocarbons (>C35).

In addition, elevated concentrations of speciated hydrocarbons (Aromatic C21-35) were reported in 3No. samples of peat at 5.30mbgl (BH210), 2.20mbgl (TP307) and 3.30mbgl (BH302).

With the exception of the significantly elevated EPH concentrations is TP03 considered to be attributable to localised source impacts, the other elevated concentrations are considered likely to be representative of the material across the site. Therefore it is considered appropriate to undertake statistical analysis for the probable landfill material, reworked topsoil and peat deposits.

Screening Summary

Exceedences of the above contaminants are typically widespread, with no significant lateral variations in concentrations identified across the site although variations between material types were identified. These elevated concentrations are therefore considered likely to reflect the wider distribution of concentrations through each deposit type across the site, thus statistical analysis is considered appropriate for each material type to further assess the potential risk to Human Health.

Statistical Analysis The statistical assessments are used to calculate representative concentrations (defined as the 95% Upper Confidence Limit) of those determinands recorded at elevated concentrations across the site. The 95%UCL is then compared to the GAC to determine if there is a significant impact on site. Outlier tests are also completed.



This statistical analysis is completed based on CIEH guidance (2008) and further details of the statistical methods of analysis are provided in Appendix C.

Table 5-2 to Table 5-4 (below) summarises the conclusions of the statistical assessment.

Table 5-2: Summary of identified impacts within Made Ground (probable landfill material)




Arsenic 35 28.32 None No significant impact

Lead 450 415



1400mg/kg in TP102 at 1.80mbgl


Nickel 130 97.74 660mg/kg in BH312


Benzo(a) anthracene



Benzo(b) fluoranthene


Chrysene 10 2.88 None No significant impact






*Based on conservative GAC values (see note in Table 5-1)

Within the probable landfill material across the site there are identified site-wide impacts of benzo(a)pyrene and localised impacts of nickel in BH312 at 5.00mbgl and lead in BH308, BH210 and TP102 at depths of 2.00mbgl, 4.00mbgl and 1.80mbgl respectively.

Table 5-3: Summary of identified impacts within Made Ground (topsoil and reworked topsoil)




Lead 450 240 650mg/kg in TP102


Benzo(a) anthracene 6.2 8.61 None Potential site-wide impact







Within the topsoil and reworked topsoil material across the site there are identified site-wide impacts of benzo(a)anthracene and benzo(a)pyrene and a localised impact of lead in TP102 at 0.30mbgl.



Table 5-4: Summary of identified impacts within Peat




Benzo(a)pyrene 1 0.45 34mg/kg in TP01 at



0.93 0.02 5.7mg/kg in TP01


Aromatic C21-35

1300 1289.49 None No significant impact

Within the peat across the site there are identified localised impacts of benzo(a)pyrene and dibenzo(a,h)anthracene in TP01 at 2.80mbgl.

5.1.4 Soil Summary

The generic screening assessment, contaminant distribution and statistical analysis and assessment following interpretation of the proposed topographic levels across the site have identified the following impacts from those contaminants identified at elevated concentrations in soils across the site.


• Localised elevated concentrations of nickel in probable landfill from BH312 (5.00mbgl);

• Localised elevated concentrations of lead in probable landfill material from BH308 (2.00mbgl), BH210 (4.00mbgl) and TP102 (1.80mbgl);

• Localised elevated concentrations of lead in reworked topsoil from TP102 (0.30mbgl);

• Site wide impact of benzo(a)pyrene within probable landfill material and topsoil;

• Site wide impact of benzo(a)anthracene within topsoil material; and

• Localised elevated concentrations of benzo(a)pyrene and dibenzo(a,h)anthracene in peat from TP01 (2.80mbgl).

5.2 Controlled Waters Assessment

5.2.1 Methodology

Details of the methodology used to define GAC are provided in Appendix C.

The GAC adopted for assessment of soil leachate and groundwater are defined based on local environmental receptors.

Typically, shallow groundwater has been encountered on site overlying the peat. In addition there is a moderately permeable aquifer within the solid geology underlying the site. Groundwater within the aquifer is typically located at the solid/superficial interface. The site does not lie within a source protection zone and there are no groundwater abstractions within 250m of the site boundary.

There are various surface drains labelled on the site plan located southwest of the site with Drumpellier Country Park, the nearest being approximately 10m from the

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Controlled Waters Assessment.. NB in Scotland we refer to Water Environment.

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Appendix C. Section C2. Presents a summary of the Risk Estimation approach from CIRIA document C552. It should be noted that this approach does not necessarily align with SEPA guidance to the assessment of significant pollution of the water environment and as such Significant Pollution may occur in situation identified by this approach as low risk by, significant pollution of the water environment may be occurring. Section 5.2.1/c3.2 Identifies that either DWS or EQS have been used as generic screening criteria based on the receptors identified for the site. The EQS listed in Appendix C have recently been revised. Appendix G has been withdrawn and new EQS have been adopted for a number of compounds. Suggest review of these new EQS and comparison of data.

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Section 5.2.1 source protection zone. Source Protection Zones are not applicable to Scotland. All groundwater lies in a drinking water protected area.



southwest site boundary. On investigation, these are surface ditches, typically dry, which are likely to fill with water during heavy rain. A photograph is included in Appendix A as Figure 2.2. The nearest surface water receptor is therefore Monkland Canal, which runs east to west and lies approximately 350m south of the site and Lochend Loch and Woodend Loch lie approximately 450m west and 650m northwest of the site boundary respectively.

Vertical migration into the underlying moderately permeable aquifer is considered to be a potential risk and any leaching during heavy rainfall may enter the drains to the southwest of the site.

The GAC used for groundwater and leachate data is therefore the freshwater Environmental Quality Standards (EQS), or in the absence of EQS, UK Drinking Water Standards (DWS) will be used. The guideline values selected as appropriate GAC for each contaminant are presented in Appendix C.

5.2.2 Leachate Screening Analysis

Leachate analysis for the selected suite of determinands was undertaken on 18No. soil samples submitted for analysis during the supplementary site investigation (RUK, 2009). 21No. soil samples were submitted for leachate analysis during the initial URS investigations in 2006 and 2008. Chemical analysis results screening tables are held in Appendix H, detailing measured concentrations of potential contaminants in comparison with the applicable GAC. Where reported analyses exceed GAC, these are highlighted within the tables. Table 5-5 provides a summary of any exceedances.

Table 5-5: Summary of Leachate Exceedences compared with relevant GAC

Determinand GAC

(µg/l)


Minimum (µg/l)

Maximum (µg/l)

Mean (µg/l)

Copper 1 26/38 <1 22 3.7 Zinc 75 4/38 <1 330 29 Ammoniacal Nitrogen 200 6/18 <20 4,900 466 Phenol 30 6/35 <0.50 8,800 683 Sulphate 400,000 1/35 1,500 540,000 43,000 Anthracene 0.02 8/33 <0.01 0.14 0.025 Fluoranthene 0.02 9/33 <0.01 0.13 0.030 Sum of 4No. PAH* 0.1 1/33 0.04 0.11 0.06 Extractable Petroleum Hydrocarbons (EPH)

10 14/18 <10 210 36


All other determinands were either reported below detection limits or were detectable at concentrations below their respective GAC.

5.2.3 Leachate Contaminant Distribution Assessment


Metals

When compared to the conservative EQS for copper (1ug/l) various samples of landfill material, topsoil and natural strata reported elevated copper concentrations.

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The GAC used for groundwater and leachate data. As a generic screen the use of EQS is protective for surface water receptors. This is not appropriate for assessing risk to groundwaters with resource potential. AS such an appropriate initial screen using generic assesment criteria would be use of the lower of EQS or Drinking water standard, or for hazardous substances MRV or LOD. A screen using these GAC would allow potentially significant issues to be taken to more detailed quantitative risk assessment. The approach used is not conservative for the following compounds: arsenic, benzene, benzo(a)pyrene, boron, chromium, , lead, nickel, phenol,

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Section 5.2.3 - copper. More detailed assessment would be appropriate to determine if this is a risk to the water environment



Due to the widespread nature of these exceedences they are considered likely to be representative of deposits across the site.

4No. samples of probable landfill material reported marginally elevated concentrations of zinc across the site.

Ammoniacal Nitrogen

Ammoniacal Nitrogen is reported to be leaching in elevated concentrations from 6No. samples; 2No. samples of probable landfill material, 3No. samples from natural strata and 1No. sample of topsoil.

Phenol

Phenols were reported as significantly elevated in 6No. leachate samples; 5No. from the probable landfill material and 1No. from natural strata.

With the exception of these 6No. exceedences all other leachate samples analysed for phenols reported concentrations below or at the detection limit. In addition, all soil samples (including those with corresponding elevated concentrations of phenols in leachate) reported concentrations of phenols below detection limit. It is therefore considered unlikely that a source of phenols exists on site which may present a significant risk to Controlled Waters.

Sulphate

Sulphate is reported as marginally elevated in 1No. leachate sample from the probable landfill material.

Organics

Leachate exceedances of anthracene and fluoranthene were reported in 8No. and 9No. soil samples respectively including probable landfill material, natural clay, topsoil and peat. Typically the most significant exceedances (an order of magnitude above the respective GAC) were reported in leachate from the probable landfill material.

1No. sample of the sum of 4No. PAHs was reported to be leaching at concentrations marginally exceeding the GAC (0.11ug/l compared to the GAC of 0.1ug/l) in a sample of reworked topsoil from 0.25mbgl. Considering the marginal and isolated nature of this exceedance it is not considered to present a significant risk to controlled waters and no further assessment is required.

Leachable concentrations of EPH were reported as elevated in 14No. samples from topsoil, natural clay, peat and the probable landfill material. The most significant exceedences were reported in the leachate from peat.

Screening Summary

Exceedences of the above contaminants are widespread within leachate, with no significant lateral variations in concentrations identified across the site although variations between material types were identified. These elevated concentrations are therefore considered likely to be representative of each deposit type across the site, thus statistical analysis is considered appropriate for each material type to further assess the potential risk to Controlled Waters.

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Phenol soil samples. The absence of delectable soil concentrations is surprising considering the concentrations of phenol detected in leachate. Review of the lab data would be appropriate and further confirmatory analysis should be considered. Noted that there is a cluster of results in the north (TP201, TP212, TP206)

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Screening Summary. Statistical analysis not demonstrated to be appropriate to made ground material. There is significant material heterogeneity that suggest statistical summary is not appropriate for this strata. Generally not appropriate to summarise leachate data statistically, but may be more appropriate for natural strata that are demonstrated to be laterally homogeneous.



Statistical Analysis

The statistical assessments are used to calculate representative concentrations (defined as the 95% Upper Confidence Limit) of those determinands reported to be leaching at elevated concentrations across the site. The 95%UCL is then compared to the EQS (or DWS where no EQS are available) to determine if there is a significant impact on site. Outlier tests are also completed. This statistical analysis is completed based on CIEH guidance (2008) and further details of the statistical methods of analysis are provided in Appendix C.

Table 5-6 and Table 5-7 (below) summarise the conclusions of the statistical assessment. Due to the limited leachate samples available from the natural strata across the site, statistical analysis is not considered appropriate and therefore Table 5-8 summarises the distribution and extent of impacts within natural strata.

Table 5-6: Summary of identified impacts leaching from Made Ground (probable landfill material)




Copper 1 3.61

22ug/l from BH206 at 2.0mbgl


2No. potential hot-spots and potential site-wide

impact

Zinc 75 103 None Potential site-wide impact

Sulphate 400,000 171,000 None No significant impact

Ammoniacal Nitrogen

200 94.3

800ug/l from HDP07 at 1.00mbgl



Phenols 30 10.8 6No. ranging from

2,500ug/l to 8,800ug/l


Anthracene 0.02 0.038 0.14ug/l in TP05 at

2.6mbgl

1No. potential hot-spot and potential site-wide

impact

Fluoranthene 0.02 0.060 None Potential site-wide impact


Within the leachate from the probable landfill material across the site there are identified site-wide impacts of copper, zinc, anthracene, fluoranthene and EPH. Localised impacts of copper, ammonium, phenols and anthracene have also been identified.

Table 5-7: Summary of identified impacts leaching from Made Ground (topsoil and reworked topsoil)




Copper 1 6.32 None Potential site-wide impact

Ammoniacal Nitrogen

200 126 280ug/l in HP02 at


Fluoranthene 0.02 0.01 0.03ug/l in TP103



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Appendix C. The legislative context presented in Appendix C is not based on current Scottish legislation and Statutory Guidance. The term Pollution of Controlled Waters is no longer applicable in Scotland. This definition was changed in the Contaminated Land (Scotland) Regulations 2005 and subsequent Statutory Guidance (2006). There are also significant differences to the Statutory Guidance to those presented in Table LC2. The details of the Statistical Methods are not included in Appendix C

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Statistical Analysis - There are insufficient samples to be representative for the individual strata. The probable landfill material may be an exception with 26 samples analysed. However not all analytes have been analysed.

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Outliers - Is any further assessment of outliers undertaken or are any recommendations made to address them



Within the leachate from the topsoil and reworked topsoil material across the site there are identified site-wide minor impacts of copper and EPH and localised minor impacts of ammoniacal nitrogen in HP02 and PAHs in TP103.

Table 5-8: Summary of identified impacts leaching from Natural Strata



Minimum (µg/l)

Maximum (µg/l)

Assessment

Copper 1 3/4 <1.6 4 Similar concentrations within the peat and clay deposits

Ammoniacal Nitrogen

200 3/3 220 1,000 Most significant exceedence

from the natural clay

Phenols 30 1/4 <0.50 3,000 Only exceedence reported

from natural clay

Anthracene 0.02 2/4 <0.015 0.07 Most significant exceedences

from the peat Fluoranthene 0.02 2/4 <0.017 0.09

EPH 10 3/3 20 210

Minimum, Maximum and Mean concentrations in relation to all data

5.2.4 Groundwater Screening Analysis

Groundwater monitoring was undertaken by URS on 1No. visit in August 2008. This section provides a full assessment of the potential risks to groundwater based on all available data.

Groundwater samples were collected from 10No. installations. The installations were screened across various strata including Made Ground deposits and underlying superficial strata including the clay, silt and peat. These installations were within the response zone of the shallow groundwater within the superficial deposits, typically perched above the peat. 1No. installation in BH207 was also screened into what is considered likely to be the underlying aquifer at the solid/superficial interface.

Chemical results from groundwater monitoring visits (2008) are presented in Appendix G. Screening tables comparing the groundwater analytical results to their respective GAC are presented in Appendix H. Exceedences of these GAC are highlighted within the tables (Appendix H) and are summarised in Table 5-9 below.

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Ammoniacal Nitrogen: the most significant exceedence in natural strata is from the natural clay. Is it possible that this is below water table? groundwater noted to be heavily impacted by ammoniacal nitrogen.

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perched above the peat - unlikely that groundwater is perched above peat. (in made ground material more likely perched on strata underlying. Are installations indicative of specific strata.

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Groundwater monitoring. Only one round of monitoring. No monitoring of full locations for this suite and no previous monitoring reported. Unlikely that monitoring was not undertaken on previous investigations. Request/find data. No information given as to why other installations have not been monitored.

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10 No. installations sampled. 16 installations not sampled.



Table 5-9: Summary of Water Exceedences compared with relevant GAC


The laboratory results indicate the following determinands were identified in concentrations above GAC in groundwater:

Metals

4No. groundwater samples reported concentrations of copper exceeding the conservative freshwater Environmental Quality Standard (EQS) of 1ug/l. None of the exceedences were more than an order of magnitude above the GAC although elevated copper concentrations were also reported in leachate from the topsoil and probable landfill material across the site.

Zinc was reported at marginally elevated concentrations in 3No. samples of shallow groundwater across the site. Elevated zinc concentrations were also reported in leachate from the probable landfill material across the site suggesting a mobile, leachable source of zinc may exist in the landfill material.

Manganese was reported as significantly elevated above the EQS of 30ug/l in all samples of groundwater analysed from across the site. Therefore there may be a mobile source of manganese on site.

pH

Marginally acidic conditions were reported in 1No. sample from BH210 and this corresponds to the acidic conditions reported in the peat at this location. Due to the marginal and isolated nature of this exceedance however, the pH is not considered to be a significant risk to Controlled Waters.

Ammoniacal Nitrogen

Significantly elevated ammonium concentrations were reported across the site when compared to the recommended EQS of 200ug/l. Elevated concentrations of ammonium were also found to be leaching from the probable landfill material across the site indicating there may be a potential source of ammonium within the probable

Determinand GAC

(µg/l)


Maximum (µg/l)

Minimum (µg/l)

Mean (µg/l)

Copper 1 4/10 5.3 <1.6 2.23

Manganese 30 10/10 7,800 1,600 2,802

Zinc 75 3/10 370 <5 75.9

Ammoniacal Nitrogen 200 10/10 16,000 600 4,920

pH 6.5-10 1/10 7.74 6.46 7.09

Nitrites 500 1/10 510 <300 118

Anthracene 0.02 3/10 0.065 <0.015 0.026

Fluoranthene 0.02 9/10 0.46 <0.017 0.143

Benzo(a)pyrene 0.03 6/10 0.29 <0.009 0.993

Sum of 4No. PAH* 0.1 6/10 1.06 0.05 0.373

Aliphatics >C21-C35 10 1/10 740 <10 83

Aromatics >C21-35 10 3/10 360 <10 89



landfill material from across the site.

Phenols

Elevated phenols were reported to be leaching from the probable landfill material and natural clay in isolated areas across the site at concentrations exceeding the GAC. However, phenol concentrations in the shallow groundwater were reported below detection limit therefore suggesting that there is not a significant risk to Controlled Waters from phenols.

Nitrites

Nitrites were reported as marginally elevated in 1No. sample of groundwater from BH311. Due to the marginal and isolated nature of this exceedance there is not considered to be a significant risk to Controlled Waters from nitrites.

Organics

Chemical analysis of groundwater indicates elevated concentrations of various PAHs (including anthracene, fluoranthene and benzo(a)pyrene) and heavy-end hydrocarbons within the underlying shallow groundwater.

9No. samples of groundwater reported concentrations of fluoranthene above the EQS of 0.02ug/l. 6No. of these samples also reported elevated concentrations of benzo(a)pyrene and sum of 4No. PAHs and a further 3No. of these reported marginally elevated concentrations of anthracene. Elevated anthracene and fluoranthene concentrations were also reported within leachate samples from across the site and elevated PAHs were also reported within soil samples from the landfill, topsoil and peat across the site. Therefore there is a potential for a leachable, mobile source of PAHs to exist on site.

Elevated concentrations of high-range organics including aliphatics >C21-35 were reported as elevated in localised groundwater from BH205 and aromatics >C21-35 were reported as elevated in localised groundwater from BH202, BH205 and BH211. Elevated hydrocarbon concentrations were reported in leachate from the landfill material, peat, natural clay and topsoil suggesting there may be a source of hydrocarbons on site. However, as impacts within the groundwater are localised it suggests the potential for hydrocarbons to leach and mobilise into groundwater is limited.

Concentrations of these contaminants do not indicate any lateral pattern of distribution to suggest a single, isolated source creating a plume of hydrocarbons within the shallow groundwater. Therefore it is considered likely that the material from across the site is leaching these contaminants in similar concentrations mobilising the contaminants into the shallow groundwater.

5.2.5 Controlled Waters Assessment Summary

The generic screening assessment and contaminant distribution assessment of the potential risks to Controlled Waters have identified particular contaminants at elevated concentrations in leachate and shallow groundwater across the site which may present a significant risk to Controlled Waters.

This assessment is based on the shallow groundwater as there are currently no installations appropriately screened into the underlying moderately permeable aquifer; typically located at the superficial/solid geology interface.




• Elevated concentrations of copper, zinc and anthracene are leaching at concentrations exceeding the GAC and are impacting the shallow groundwater at similar concentrations;

• Elevated concentrations of ammoniacal nitrogen are reported in leachate, typically from the probable landfill material on site but also from localised areas of natural materials and topsoil on site. Concentrations are typically more significantly elevated within the shallow groundwater on site. The significantly elevated concentrations of ammonia within groundwater are considered likely to be attributable to the breakdown of organic components within the landfill waste and subsequent leaching as no cap was placed above the waste material to minimise leaching. As the landfill is thought to have closed in 1972, it is likely that concentrations of ammonia within leachate would have been significantly higher than at present, thus increasing the concentration of ammonia within the shallow groundwater across the site. The breakdown of any organic contaminants within the landfill will be reducing over time and this is reflected in the concentrations of ammonia within the leachate;

• Fluoranthene and PAHs (sum of 4No.) are leaching at elevated concentrations most significantly from the probable landfill material across the site but also from localised areas within the topsoil and peat deposits. These contaminants are reported at significantly higher concentrations within the shallow groundwater on site and elevated concentrations of benzo(a)pyrene are also reported in groundwater although no elevated concentrations were reported within leachate (typically reported below detection limit). Higher concentrations of these contaminants within the shallow groundwater rather than leachate are likely due to the decreasing decay of organic matter within the landfill material over time, as discussed above. Benzo(a)pyrene is likely no longer being leached from organic materials within the landfill material as the bacterial decay of this organic material has occurred previously and the impacts from subsequent leaching are revealed only within the groundwater data;

• Concentrations of EPH within leachate are elevated within the landfill, topsoil and natural material across the site. However, all speciated TPH leachate data from C5-C35 reported concentrations below detection limit suggesting the only significant impacts are from heavy-end organics greater than C35. In addition, only localised impacts of heavy-end organics (greater than C21) are reported in shallow groundwater across the site. These organics are unlikely to be highly mobile within the water environment, which is demonstrated by the isolated impacts within shallow groundwater;

• Manganese is an essential element in the production of steel and it is known that waste from the Gartcherrie Steel Works was disposed of annually at the former Townhead Landfill, underlying the site. It is likely that leaching of this material within the landfill resulted in migration of manganese into shallow groundwater, therefore explaining the significantly elevated concentrations of manganese across the site. As detailed above, it is likely that manganese represents a finite source and concentrations within the leachate and the shallow groundwater will reduce over time; and

• Phenols were reported as significantly elevated in leachate from 5No. samples of probable landfill and 1No. sample of natural strata. Considering the concentrations of phenols within soils, all other leachate samples and

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EPH Concentrations of EPH in leachate are less than the summed total of concentrations for banded analysis. So reliance on heavier end is questionable.



all groundwater samples reported concentrations of phenols below or at the detection limit it is considered unlikely that a significant source of phenols exists on site.

All site wide impacts are considered to be only marginally above the recommended GAC. Only localised impacts have been reported at slightly higher concentrations. The decreased concentrations reported in all strata indicate that there is likely to be only a limited ongoing source of leachable contaminants, which have the potential to impact the underling shallow groundwater.

5.3 Ground Gas Risk Assessment

A ground gas monitoring programme was undertaken by URS as part of the investigations in 2006 and 2008/9. An assessment of the risk presented by any potential ground gas on site was undertaken as part of the Ground Investigation Report (URS, 2008) which concluded additional ground gas monitoring would be required. 12No. rounds of ground gas monitoring were undertaken between November 2008 and April 2009 and interpreted within the letter provided in Appendix I (reference 49339729/GLLT0015, May 2009).

The section provides a full assessment of all the gas monitoring data available for the site in accordance with CIRIA C665 and BS8485, taking into accounts the comments made by URS. Further details of the assessment methodology are provided in Appendix C.

All available ground gas monitoring data is included within Appendix J. Table 5-10 provides a summary of the maximum and minimum gas concentrations and flow rates reported in each borehole monitored from 2006 to 2009.

Table 5-10: Summary of Ground Gas Monitoring Visits

Borehole Response

Zone

Depth to GW

(mbgl)

Flow rate (l/hr)*


Max. GSV

CS (C665)

CH4 CO2 O2


BH1 (2006) MG 2.08-4.69 2.5 0.05 0.1 <0.1 5.8 <0.1 21.6 5.8 0.145 2

BH2 (2006) MG 4.00-4.20 2.4 0.2 4.0 <0.1 12.6 <0.1 3.8 <0.1 0.302 2

BH3 (2006) MG 3.37-4.65 2.2 -0.3 0.1 <0.1 6.2 <0.1 20.8 <0.1 0.136 2

BH201 (2008) MG 3.11-3.23 <0.1 <0.1 <0.1 <0.1 1.7 0.8 18.1 16.8 0.0017 1

BH202 (2008) Peat 5.22-5.36 <0.1 <0.1 68.7 65.3 30.2 20.0 <0.1 <0.1 0.0687 2

BH203 (2008) MG 3.54-3.77 <0.1 <0.1 <0.1 <0.1 1.9 1.5 18.8 18.2 0.0019 1

BH204 (2008) Peat 2.90-3.04 <0.1 <0.1 <0.1 <0.1 2.5 1.9 18.2 17.7 0.0025 1

BH205 (2008) MG 3.94-4.04 <0.1 <0.1 3.7 2.7 4.8 2.9 13.9 13.1 0.0048 1

BH206 (2008) MG Dry <0.1 <0.1 <0.1 <0.1 2.3 1.7 18.4 17.8 0.0023 1

BH207 (2008) Silt/Clay

/Peat 4.30-4.48 <0.1 <0.1 <0.1 <0.1 0.8 0.6 20.4 20.1 0.0008 1

BH208 (2008) Peat 4.21-4.31 <0.1 <0.1 10.2 8.3 9.6 6.9 8.9 6.7 0.0102 2

BH209 (2008) MG Dry <0.1 <0.1 <0.1 <0.1 3.7 2.5 16.7 16.1 0.0037 1

BH210 (2008) Peat 6.01-6.15 <0.1 <0.1 <0.1 <0.1 0.1 <0.1 20.6 20.1 0.0001 1

BH211 (2008) MG 2.85-3.00 <0.1 <0.1 <0.1 <0.1 12.3 9.8 10.2 7.8 0.0123 2

BH213 (2008) MG 4.90-4.91 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 20.8 20.7 0.0001 1

BH301(2008) MG 2.48-2.96 <0.1 <0.1 <0.1 <0.1 3.9 2.9 16.1 15.7 0.0039 1


/Peat 7.80-8.14 <0.1 <0.1 66.2 62.1 23.3 20.5 0.7 <0.1 0.0662 2

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phenols. In the absence of soil concentrations we would recommend review of lab data and re-sampling of soils in areas where elevated leachate concentrations were identified. Also groundwater sampling in these locations should be undertaken for phenols. Only one leachate sample is in a location where there is any groundwater sampling nearby.

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decreased concentrations - Decreased in relation to what? There is no evidence of decrease in contaminants. This statement requires clarification.

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"site wide impacts are considered to be only marginally above the recommended GAC" This statement is not accurate. If by impacts they are referring to actual concentrations found in groundwater are not marginal exceedences.

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underling shallow groundwater. On the basis of the identified potential linkages, it is appropriate to take forward the risk assessment to a detailed quantitative risk assessment assessing risks to groundwater receptors. Groundwater in bedrock should be assessed. Groundwater in superficial deposits should be assessed for it's potential as a water body.

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Table 5-10. Shows gas and groundwater monitoring for a number of visits. The response zones for BH202 (2008) and BH2004 (2008) are different to the BH202(2008/2009) and BH2004 (2008/2009) samples. Are these the same boreholes?



Borehole Response

Zone

Depth to GW

(mbgl)

Flow rate (l/hr)*


Max. GSV

CS (C665)

CH4 CO2 O2


BH303(2008) MG 1.61-2.21 <0.1 <0.1 0.3 0.2 18.4 16.8 1.9 1.1 0.0184 2


/Peat 3.90-4.02 <0.1 <0.1 9.1 7.9 5.1 3.9 16.9 16.3 0.0091 2

BH305(2008) Silt/Clay 6.05-6.27 <0.1 <0.1 34.8 28.9 20.0 18.7 10.5 9.7 0.0348 2

BH306(2008) MG Dry-2.55 <0.1 <0.1 <0.1 <0.1 0.4 0.1 20.7 20.4 0.0004 1

BH307(2008) MG 2.61-2.88 <0.1 <0.1 <0.1 <0.1 13.7 11.7 7.5 6.1 0.0137 2

BH308(2008) MG/Peat 2.45-3.49 <0.1 <0.1 47.4 38.9 23.2 20.7 5.8 4.2 0.0232 2

BH309(2008) Peat Dry-2.87 <0.1 <0.1 16.8 15.3 21.7 20.5 4.8 4.5 0.0217 2

BH310(2008) MG 2.03-2.49 <0.1 <0.1 <0.1 <0.1 0.6 <0.1 20.7 20.1 0.0006 1

BH311 (2008) MG 2.58-2.75 <0.1 <0.1 <0.1 <0.1 16.8 14.7 3.3 2.3 0.0168 2

BH312 (2008) MG/Peat/ Sand/Clay

Dry <0.1 <0.1 <0.1 <0.1 0.8 0.5 19.9 19.5 0.0008 1

BH313 (2008) MG Dry <0.1 <0.1 <0.1 <0.1 12.9 12.9 3.0 3.0 0.0129 2

BH201 (08/09) MG 3.12-3.28 0.2 <0.1 0.2 <0.1 14.2 0.3 19.3 1.1 0.028 2

BH202 (08/09) MG Dry-3.81 0.2 <0.1 66.9 <0.1 14.5 <0.1 19.7 <0.1 0.029 2

BH203 (08/09) MG 3.21-4.52 0.2 <0.1 3.1 0.1 9.9 1.7 16.5 <0.1 0.0198 2

BH204 (08/09) MG 2.16-2.73 0.2 <0.1 18.6 0.1 16.9 4.2 17.6 7.4 0.0372 2

BH205 (08/09) Peat 3.34-3.75 0.1 <0.1 0.5 <0.1 15.3 5.2 20.1 0.1 0.0153 2

BH206 (08/09) MG Dry-4.35 0.2 <0.1 0.1 <0.1 15.9 7.4 12.4 1.7 0.0318 2

BH207 (08/09) Peat 3.85-4.23 0.3 <0.1 <0.1 <0.1 21.7 5.0 15.1 5.3 0.0651 2

BH208 (08/09) MG 3.61-3.95 0.1 <0.1 2.8 1.9 7.6 3.5 19.3 9.5 0.0076 2

BH209 (08/09) MG Dry-4.68 0.1 <0.1 <0.1 <0.1 5.2 0.2 20.6 13.8 0.0052 1


/Peat 4.72-6.03 0.1 <0.1 75.4 <0.1 22.7 <0.1 17.1 <0.1 0.0754 2

BH211 (08/09) Peat 2.34-2.65 0.3 <0.1 1.0 <0.1 13.0 <0.1 19.4 <0.1 0.039 2

BH213 (08/09) MG 5.08-5.46 0.7 <0.1 <0.1 <0.1 2.1 <0.1 20.9 18 0.0147 1

BH301 (08/09) Peat 2.97-2.99 0.1 <0.1 0.5 <0.1 4.0 <0.1 20.6 <0.1 0.004 1

BH302 (08/09) MG 7.61-7.90 0.2 <0.1 52.5 <0.1 23.5 <0.1 0.5 <0.1 0.105 2

BH303 (08/09) MG Dry-1.77 0.1 <0.1 9.5 <0.1 18.2 5.7 11.8 <0.1 0.0182 2

BH304 (08/09) MG 3.89-4.04 1.4 <0.1 69.1 <0.1 31.8 <0.1 10.7 <0.1 0.967 3


/Peat Dry-5.90 1.8 <0.1 62.1 1.1 32.2 1.3 18.9 3.1 1.12 3

BH306 (08/09) MG Dry-2.47 0.1 <0.1 1.1 <0.1 5.9 1.6 19.1 <0.1 0.0059 2


/Peat 2.14-2.52 0.4 <0.1 0.5 <0.1 16.2 5.3 19.5 2.0 0.0648 2

BH308 (08/09) Silt/Clay 0.79-0.79 10.9 <0.1 14.8 <0.1 20.9 2.5 18.7 2.2 2.28 3

BH309 (08/09) MG Dry-1.90 0.3 <0.1 <0.1 <0.1 3.6 0.8 20.4 17.6 0.0108 1

BH310 (08/09) MG Dry-1.83 0.2 <0.1 <0.1 <0.1 14.6 0.2 20.4 0.3 0.0292 2

BH311 (08/09) MG/Peat Dry-2.20 0.1 <0.1 <0.1 <0.1 16.0 1.8 20.3 <0.1 0.016 2

BH312 (08/09) Peat Dry-10.01 <0.1 <0.1 0.4 <0.1 5.3 0.1 20.9 9.4 0.0053 2

BH313 (08/09) MG Dry 0.2 <0.1 <0.1 <0.1 11.5 0.2 20.6 6.5 0.023 2

Worst Case Scenario 10.9 75.4 32.2 - 8.22 4

*Negative flow rates are reported at below detection limit for the purpose of calculating the GSV



From a review of the available ground gas data the concentrations reported would classify the proposed development as Characteristic Situation 4 based on a worst case scenario, assuming the highest methane concentration (75.4%) and flow rate (10.9l/hr) could occur simultaneously on site. The highest methane concentrations were reported from the natural peat deposits underlying the site.

It is considered that this is a highly conservative assessment. The elevated flow rate of 10.9l/hr was only recorded on 1No. occasion from 1No. well. In the same well flow rates were reported between 0.1l.h and negative 12.5l/hr during all other visits, suggesting the extremely elevated flow rate is an anomalous result. Typically the flow rate across the site is 0.1-1.8l/hr.

In addition, there are issues with the well which reported this elevated flow rate (BH308). This well is screened from 1.00-11.00mbgl, however water level during the first visit was reported above the screen (0.78mbgl) which may interfere with the results. Following the first visit, URS reported the bung was “jammed down standpipe” so the groundwater could not be monitored again. Therefore it is likely a combination of interference of groundwater and inappropriate monitoring of this borehole has caused this anomalous result. Omitting this anomalous flow rate would result in a worst case GSV of 1.36l/hr therefore classifying the site as CS3.

The proposed development is a sensitive end-use and there is a high risk of ground gas generation from various sources across the site. As a result of these factors and following consultation with North Lanarkshire Council, classification of the site as Characteristic Situation 4 is considered to be appropriate.



6 GROUND CONTAMINATION

6.1 Conceptual Site Model

The information presented in the previous sections of this report have been collated and evaluated to refine the initial conceptual site model for the site. This updated conceptual site model is illustrated in cross-section form in Appendix A, Drawing No. 5311/E/004.

6.1.1 Sources

The following sources of potential contamination have been identified based on the available information from the initial investigations in 2006 and 2008 (URS) and the supplementary investigation in 2009 (Ramboll):

• Potential soil contamination which may pose a risk to Human Health:

- Localised elevated concentrations of nickel in probable landfill from BH312

- Elevated localised concentrations of lead reported in probable landfill material in the area of BH308, BH210 and TP102;

- Localised elevated concentrations of lead, reported in reworked topsoil material in TP102 at 0.30mbgl;

- Site wide impacts of benzo(a)pyrene within the probable landfill material and topsoil;

- Site wide impacts of benzo(a)anthracene within the topsoil material; and

- Localised elevated concentrations of benzo(a)pyrene and dibenzo(a,h)anthracene, reported in TP01 within the peat.

• Potential leachate and groundwater contamination which may pose a risk to Controlled Waters:

• Marginally elevated concentrations of copper, zinc and anthracene within leachate from across the site, which is impacting the shallow groundwater;

• Elevated concentrations of ammoniacal nitrogen within the shallow groundwater continuing to leach from materials across the site at slightly elevated concentrations;

• Fluoranthene and PAHs (sum of 4No.) are leaching at elevated concentrations most significantly from the probable landfill material across the site;

• Localised elevated concentrations of aliphatic and aromatic C21-35 are reported in shallow groundwater and concentrations of EPH (C10-C40) are reported to be leaching at elevated concentrations from material across the site;

• Elevated manganese within the shallow groundwater across the site, likely a result of leaching from landfill material across the site;

• Elevated phenols were reported as elevated within leachate samples from isolated areas of landfill material and natural strata; and

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manganese. There is manganese identified in groundwater. No soil analysis has been undertaken for manganese. As such it has not been established if there is a source on site.



• Elevated ground gas concentrations including methane and carbon dioxide.

6.1.2 Receptors

The site-specific receptors that could potentially be affected by the contamination hazards have been identified in the preliminary conceptual model in Section 2.6.2. Receptors include:

• Future site users – school children, staff and the general public; • Site development workers; • Underlying aquifer and surface water features; • Construction materials; • Adjacent site users and structures; and • Site vegetation.

6.1.3 Pathways

The following potential contaminant pathways are considered likely to exist on site given the nature of the site and the contamination sources identified:

• Dermal contact with and ingestion of soils; • Plant uptake;

Direct contact pathways and plant uptake will only be active in areas of landscaping with the exception of the sports pitches. The proposed make-up of the pitches includes 250mm-350mm of imported clean fill material which will be separated from the probable landfill material below by a visqueen membrane. Based on these measures across the pitches and the reported concentrations of contaminants, direct contact pathways within the areas of the sports pitches are not considered active.

As the source areas are both localised and site-wide, further consideration is given below as to the location of localised impacts within the proposed development to determine whether these pathways will be active.

The localised elevated concentrations of lead reported in probable landfill material in the area of BH308, BH210 and TP102 and nickel reported in probable landfill material from BH312 were reported in samples at depths exceeding 1.80mbgl. In addition, localised elevated concentrations of lead were also reported in topsoil material in TP102 at 0.30mbgl. However, these samples are from strata which persist to shallower depths of a minimum of 0.05mbgl and although based on current cut and fill proposals these hotspots are in areas of fill, existing site levels will need to be reduced prior to construction. The materials cut from these areas may therefore present a potential risk to Human Health via direct contact pathways.

Localised elevated concentrations of benzo(a)pyrene and dibenzo(a,h)anthracene were reported in TP01 within the peat at a depth of 2.80mbgl. These contaminants are considered to be naturally occurring within the peat and are at a depth considered unlikely to affect future site users via direct contact due to the levels of fill proposed in this area.

Site wide impacts of benzo(a)pyrene have been identified in the probable landfill and topsoil material across the site and side wide impacts of benzo(a)anthracene have also been identified in topsoil. These contaminants may therefore present significant risk in areas of soft landscaping via the direct contact pathway to future site users.

• Ground gas migration;



• Inhalation of dusts and vapours; • Leaching and subsequent migration of mobile impacts;

There will be an overall increase in hardstanding across the site and the proposed sports pitches will include a visqueen membrane and surface water drainage system, which will limit rainfall infiltration and the leaching potential of soils. In addition, across the majority of the site the probable landfill material is separated from the solid geology (and therefore moderately permeable aquifer) by peat and/or superficial clay, which is likely to restrict the vertical migration of contaminants from the shallow groundwater, into the aquifer below.

Soakaways are currently proposed in 2No. areas on site, near TP01 in the southwest area of site and underlying the pitch in the southeast corner of site near TP03, TP04 and TP05. In the southeast area of the site, marginal impacts of copper, ammonium, anthracene, fluoranthene and EPH were reported in leachate from probable landfill and natural strata in these areas. Marginally elevated concentrations of lead, dibenzo(a,h)anthracene and EPH were reported in localised soils in this area but these are not considered to be significant.

In samples from TP01 elevated EPH, benzo(a)pyrene and dibenzo(a,h)anthracene were reported in soil samples from the peat in this location. Marginally elevated anthrancene and fluoranthene were reported within leachate from the landfill material and marginally elevated copper, ammonium, anthracene, fluoranthene and EPH were reported in peat. These elevated concentrations are not considered to be significant.

Although the concentrations of benzo(a)pyrene and dibenzo(a,h)anthracene reported in the soils are significant, leachate results reported these contaminants at concentrations below detection limit, therefore suggesting this soil source is not mobile in the water environment. These concentrations of the contaminants reported within leachate are not considered to be significant.

6.2 Qualitative Risk Assessment

Potential pollutant linkages are identified using the source-pathway-receptor framework detailed above. An assessment of the potential significance of each linkage is then made by consideration of the likely magnitude and mobility of the source, the sensitivity of the receptor and nature of the migration/exposure pathways.

This qualitative hazard assessment has been undertaken in accordance with CIRIA C552: Contaminated Land Risk Assessment, A Guide to Good Practice. Further details of the methodology used and definition of the risk categories is provided in Appendix C.

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Soakaways. A detailed risk assessment should be undertaken to demonstrate that the use of soakaways will not result in the mobilisation of contaminants from Landfill material/Made grounds at those locations. The framework for assessment is that for a new activity as outlined in our draft Position Statement PS_XX. The presence of hazardous substances in leachate samples and the shallow groundwater across the site suggests that infiltration through soakaways would cause entry of hazardous substances. Previous advice in our letter to North Lanarkshire Council Planning and development department dated 11 September 2009 ref PCS/102360 your ref C/09/00818/FUL advises that the applicant should follow the principles and guidance in the SUDS Manual (C697)

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leachate results. reliance on organic leachate results is not appropriate and a screen of potential leachability calculated from total soil concentrations using partition coefficients is appropriate.

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There will be an overall increase in hardstanding across the site and the proposed sports pitches will include a visqueen membrane and surface water drainage system, which will limit rainfall infiltration and the leaching potential of soils. In addition, across the majority of the site the probable landfill material is separated from the solid geology (and therefore moderately permeable aquifer) by peat and/or superficial clay, which is likely to restrict the vertical migration of contaminants from the shallow groundwater, into the aquifer below. design noted. further detail should be provided. What is specification for visqueen (low permeability)? No assessment of peat or clay permeability has been carried out. Appropriate risk assessment shouild be carried out for post development setting. Detail of the drainage and areas of infiltration should be considered in the risk assessment.



Table 6-1 summarises the pollutant linkages and risk ratings associated with the proposed development.

Table 6-1: Hazard Assessment


Probability Of Risk

Level Of Risk

Localised elevated soil concentrations of lead in topsoil, lead and nickel

in landfill material





Medium Low LOW /

MODERATE


groundwater


Mild Low LOW


Medium Unlikely LOW



Mild Low LOW

Localised elevated soil concentrations of PAHs

in peat





Medium Unlikely LOW


groundwater


Mild Low LOW


Medium Unlikely LOW



Mild Low LOW

Site-wide impacts of benzo(a)pyrene in

landfill material and topsoil and site-wide

impacts of benzo(a)anthracene in

topsoil



Future site users Medium Likely MODERATE


Medium Likely MODERATE


groundwater


Mild Low LOW


Medium Unlikely LOW



Minor Likely LOW

Marginally elevated copper and zinc within



Mild Low LOW

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Table 6-1: Hazard Assessment. The levels of hazard assessment ascribed to the water environment receptors is not appropriate. No consideration has been given to contaminant hot-spots and their impact on the water environment. An appropriate DQRA should be carried out establishing a correct water environment receptor system for groundwater in more detail.




Probability Of Risk

Level Of Risk

leachate and shallow groundwater

groundwater Surface water (Monkland Canal; Lochs)

Mild Unlikely VERY LOW

Secondary Aquifer Mild Low LOW


Mild Low LOW

Elevated manganese, ammonia and PAH

within shallow groundwater and

leachate.


groundwater


Mild Low LOW


Medium Unlikely LOW



Mild Low LOW

Localised elevated hydrocarbons within shallow groundwater

• Migration of groundwater


Mild Low LOW


Medium Unlikely LOW



Mild Low LOW

Localised marginally elevated concentrations of EPH, PAH, ammonium

and copper within leachate in the areas of the proposed soakaway


groundwater


Mild Low LOW


Medium Unlikely LOW



Mild Low LOW

Generation of potentially hazardous ground gas

Ground gas migration

Site users Severe Likely HIGH


Severe Likely HIGH

*Given the use of appropriate PPE and health and safety precautions, risk to workers would be reduced to low.



The risks to Human Health via direct contact with lead and nickel in localised areas across the site including TP102, BH308, BH210 and BH312 are considered to be LOW / MODERATE as these materials are at depths proposed to be excavated as part of the cut and fill works.

Localised elevated concentrations of PAHs are located in areas of proposed fill with at least 600mm of fill or existing material located above the source strata. Therefore these localised impacts are unlikely to present a risk via direct contact pathways. Risks to Human Health from these impacts are therefore considered to be LOW.

Risks to human health caused by elevated benzo(a)pyrene in probable landfill and topsoil material across the site and elevated benzo(a)anthracene in topsoil are considered likely to be significant in areas of soft landscaping where there will be an active direct contact pathway. Therefore the risk to human health from benzo(a)pyrene and benzo(a)anthracene is classified as MODERATE. Risks to vegetation in any planted areas caused by plant root uptake of these contaminants are considered to be LOW.

Risks to the Secondary Aquifer underlying the site are classified as LOW / MODERATE due to the impacts of manganese, ammonia and PAH within the shallow groundwater. Risks to the underlying aquifer from the localised hydrocarbons and marginal impacts of copper and zinc already identified within the shallow groundwater are classified as LOW. Due to the significant depths of impermeable deposits including peat and clay overlying the aquifer in the majority of locations across the site it is considered unlikely that significant vertical migration of contaminants will occur.


The development proposals include increasing the area of hardstanding across the site thus reducing leaching potential and likely pathways. Based on the significant distance to the nearest surface water receptor (Monkland Canal; Lochend and Woodend Lochs all >350m from the site) and the proposed development minimising pollutant linkages, the risks to the surface water receptors are considered to be LOW.

Risks to future site users from the generation, migration and accumulation of potentially hazardous ground gases in confined spaces resulting in asphyxiation or explosion are considered to be HIGH.

6.3 Development Considerations

Activities on-site that could affect ground conditions potentially include piling operations, foundation design, earthworks, installation of underground services and provision of drainage infrastructure.

Any piled solution to foundation design should be developed in such a way so that the installation of the piles themselves does not create preferential flow pathways by which potential contamination could mobilise in the unsaturated zone.

Foundation design should take into consideration the potential to encounter aggressive ground conditions beyond those identified during the site investigation.

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impermeable deposits including peat and clay. Peat is unlikely to be impermeable Clay may have low permeability. Does not take into consideration preferential pathways of mine shafts and the location of these in relation to groundwater flow direction.



As the development is proposed to comprise buildings and hard-standing, with associated areas of soft landscaping, infiltration of rainwater may be reduced compared to the present situation, with limited potential for leaching and downward migration of potential contaminants to the underlying groundwater.

Soakaways are proposed in 2No. areas of site. The design of these soakaways must take into account the marginal contamination impacts identified in these areas. Although rainfall and surface water infiltration will be encouraged in these areas, the soakaways have been strategically placed towards the south of the site away from the main hub of the landfill to minimise infiltration through the landfill material. In addition, it is considered that the proposed drainage across the entire site will minimise infiltration and leaching through the landfill, therefore improving upon the current situation at the site.

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proposed drainage. It is suggested that the proposed drainage will minimise infiltration. No information has been provided as to the layout of the drainage and how this will reduce /limit infiltration and in what locations. The characteristics of the proposed playing fields has not been described in this document.

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hard-standing. the presence of hard-standing may reduce infiltration in certain locations. The distribution of hard-standing should be presented with consideration of the distribution of contaminants and assessment of the reduction of infiltration and the potential sources of contamination that are not covered.

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Consideration should be given to the groundwater level and how it sits in relation to the contamination sources. Are these saturated. If so then reduction in infiltration will not break the linkage for lateral migration in groundwater.



7 RISK MANAGEMENT STRATEGY

7.1 Significant pollutant linkages

Potentially significant pollutant linkages have been identified during the ground contamination risk assessment. These are:

• Risks to Human Health through direct contact pathways with elevated benzo(a)pyrene in probable landfill material across the site;

• Risks to Human Health through direct contact pathways with elevated benzo(a)pyrene and benzo(a)anthracene in topsoil material across the site;

• Risks to Controlled Waters through vertical migration of contaminants including manganese, ammonia, PAH, localised hydrocarbons, copper and zinc from the shallow perched groundwater into the deep aquifer, particularly within the areas of the proposed soakaways; and

• Risks to Human Health through the generation, migration and accumulation of potentially hazardous ground gases (methane and carbon dioxide) in confined spaces resulting in asphyxiation or explosion.

No risk management strategy is proposed for site development workers as any potential risks should be managed through the implementation of standard health and safety precautions, such as the use of appropriate personal protective equipment (PPE).

7.2 Recommendations

7.2.1 Additional Assessment and Investigation

In order to further assess the potential risks to Human Health caused by the site-wide impacts of benzo(a)anthracene in topsoil and benzo(a)pyrene in topsoil and landfill material it is recommended that a Detailed Quantitative Risk Assessment (DQRA) is undertaken in order to derive more appropriate site-specific assessment criteria for these contaminants.

Further investigation into the potential risks to the underlying aquifer including additional groundwater sampling from the shallow groundwater and underlying aquifer across the site may be required in order to further assess the potential risks to Controlled Waters, particularly considering soakaways are proposed in 2No. areas of site.

7.2.2 Proposed Remedial Measures

In addition and based on the information available to date, there is likely to be a requirement for remedial action to progress the development.

The following recommendations are made in order to reduce risks to human health from identified ground gas impacts assuming Characteristic Situation 4:

a) Reinforced concrete cast in situ floor slab (suspended, non-suspended or raft) or beam and block or pre-cast concrete slab;

b) All joints and penetrations sealed; and

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Risks to Controlled Waters through vertical migration of contaminants including manganese, ammonia, PAH, localised hydrocarbons, copper and zinc from the shallow perched groundwater into the deep aquifer, particularly within the areas of the proposed soakaways; This does not concur with the information presented in the hazard assessment and CSM, but is more accurate (i.e. that potentially significant pollutant linkages have been identified for risk to water environment)

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Further investigation into the potential risks to the underlying aquifer including additional groundwater sampling from the shallow groundwater and underlying aquifer across the site may be required in order to further assess the potential risks to Controlled Waters, particularly considering soakaways are proposed in 2No. areas of site. This recommendation is vague.



c) Proprietary gas resistant membrane and passively ventilated underfloor subspace or positively pressurised underfloor sub-space, oversite capping or blinding and in ground venting layer. (in accordance with CIRIA C665/ BS8485)

Ramboll have consulted with a leading contractor in the design and installation of ground gas protection systems. Based on the maximum concentrations of methane and carbon dioxide and the maximum flow rate recorded on site a high performance passively ventilated system has been designed. The proposal for this system is included in Appendix K.

In addition, hotspots of lead and nickel were identified in localised areas across the site, typically at depths exceeding 1.80mbgl. Based on current proposals these impacts are in areas of fill but prior to the fill works, material from these areas will require excavation in order to obtain finished site levels. This excavated material may present a risk to Human Health via the direct contact pathway. It is therefore proposed that during enabling works, material excavated from these areas is stockpiled separately and subjected to validation testing to establish whether the material is suitable for reuse.

There remains the potential for ground conditions to vary in areas not directly investigated.

7.3 Additional considerations for development

Cut and Fill Works Any excavation works on site may encounter volumes of potentially contaminated groundwater, which was recorded at depths ranging from 1.90mbgl to 4.70mbgl. Allowances are recommended to be made for the removal, treatment and disposal of shallow groundwater should dewatering be required during excavation.

Significant cut and fill works are proposed for the site and there is a potential for contaminated materials not previously identified to be uncovered on site. It is therefore recommended that a suitably qualified Environmental Consultant is on site during the enabling works to ensure that should any areas of apparent contamination be exposed; the material is excavated, stockpiled separately onsite and subjected to validation testing in order to ensure the material is suitable for use.

Waste Disposal Any excavation/piling may result in soils that require off-site disposal, if they are unsuitable for reuse on site. All excavated materials will be controlled waste. Further assessment will be required to establish classification (hazardous or non-hazardous) and further chemical testing (and/or pre-treatment) if disposal to landfill is considered. Some form of pre-treatment of those materials to be disposed to landfill (e.g., screening to remove oversized ‘clean’ demolition material and gravels) may significantly reduce the volume of material liable to classify as hazardous waste.

Environmental Specification It is recommended that an Environmental Specification Report is produced in order to ensure the Contractor is undertaking all enabling works in accordance with the recommendations above.

Validation Works Validation sampling will be required from all materials cut from site during enabling works in order to ensure all materials are suitable for use. These results, along with documented evidence to illustrate that the remedial measures detailed above and within the Environmental Specification have been adhered to, will need to be



documented in a Validation Report and submitted to the Environmental Department at North Lanarkshire Council.

Underground Services Laying underground services in potentially contaminated Made Ground materials has the potential to establish preferential flow pathways and therefore materials should be used appropriate to the level of contamination identified on site, particularly with regard to underground mains water supply. Consultation with Scottish Water is advised.

Asbestos No asbestos-containing material (ACM) has been identified on site. However, as the site has been historically redeveloped and used as a landfill, localised deposits of asbestos-containing materials have the potential to be present in Made Ground across the site. Appropriate health and safety precautions (i.e., provision of appropriate PPE to site development workers, etc.) should be adopted during enabling works.


5311.E.GQRA.1A Appendices

8 REFERENCES

BS 5930 (1999) Code of Practice for Ground Investigation

BS 8485 (2007) Code of practice for the characterization and remediation from ground gas in affected developments. British Standards Institute 2007

CIRIA 552 (2001) Contaminated land risk assessment – a guide to good practice. London

CIRIA C665 (2007) Assessing risks posed by hazardous ground gases to buildings. London

Contaminated Land: Applications in Real Environments (CL:AIRE) and Chartered Institute of Environmental Health (CIEH) (2008) Guidance on Comparing Soil Contamination Data with a Critical Concentration (May 2008)

Department for Environment, Food and Rural Affairs (DEFRA) and the Environment Agency (EA) (2002) CLR 8: Potential Contaminants for the Assessment of Land

Department for Environment, Food and Rural Affairs (DEFRA) and the Environment Agency (EA) (2002) CLR 11: The Model Procedures for the Management of Land Contamination

Environment Agency, 2009a SR2 Human Health toxicological assessment of contaminants in soil SC050021/SR2 (January 2009)

Environment Agency, 2009b SR3 Updated technical background to the CLEA model SC050021/SR3 (January 2009)

Scottish Environmental Protection Agency (SEPA) 2009 www.sepa.org.uk (Accessed throughout November 2009)

Eurocode 7 (2007) Geotechnical Design –BS EN 1997-2:2007

LQM/CIEH (2007) Generic Assessment Criteria for Human Health Risk Assessment. Land Quality Management Ltd and Chartered Institute of Environmental Health

Multimap (2009) www.multimap.co.uk (Accessed throughout November 2009)

Ordnance Survey (2009) www.ordnancesurvey.co.uk (Accessed throughout November 2009)

Planning Policy Statement 25 (PPS25): Development and Flood Risk. December 2006

Summary of Comments on 5311e001 hole location plan.pdfPage: 1

Author: murray.dobson Subject: Oval Date: 04/02/2010 16:49:21 Slight organic odour Author: murray.dobson Subject: Oval Date: 04/02/2010 17:01:07 Slight organic odour Moderate Hydrocarbon Odour Author: murray.dobson Subject: Oval Date: 04/02/2010 17:01:56 Moderate hydrocarbon odour

Author: murray.dobson Subject: Oval Date: 04/02/2010 17:02:23 Moderate to strong rotting odour Moderate/Slight Hydrocarbon Odour Author: murray.dobson Subject: Oval Date: 04/02/2010 17:00:27 Moderate to strong rotting odour Author: murray.dobson Subject: Oval Date: 04/02/2010 16:50:01 Slight organic odour Author: murray.dobson Subject: Oval Date: 04/02/2010 16:50:36 Moderate organic odour

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Rectangle

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phenol leachate > 1000

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phenol leachate =10

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phenol leachate =10

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Slight organic odour Moderate Hydrocarbon Odour

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Moderate to strong rotting odour Moderate/Slight Hydrocarbon Odour

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Moderate to strong rotting odour

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soakaway location

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St Ambrose

Ground Contamination Detailed Quantitative

Risk Assessment

For

Balfour Beatty

DECEMBER 2009

Project No.: 5311


12/13 St. Andrew Square,

Edinburgh. EH2 2AF

tel 0131 550 4070

fax 0131 550 4093

[email protected]

5311 E DQRA 1A Revision History

Ground Contamination Detailed Quantitative Risk Assessment

St Ambrose

Balfour Beatty

Revision History

Rev Date Purpose/ Status

Document Ref. Comments

1 December

2009

Final 5311 E DQRA 1A Final

Author:

Checked by:

Approved by:

Environmental Engineer

Senior Environmental

Consultant

Director

St Ambrose Ground Contamination Detailed Quantitative Risk Assessment

5311 E DQRA 1A Contents

CONTENTS

CONTENTS 1

1 INTRODUCTION 1

1.1 BACKGROUND 1

1.2 AIMS AND SCOPE OF WORKS 2

1.3 CONSTRAINTS AND LIMITATIONS 2

2 SITE DETAILS 3

2.1 SITE LOCATION 3

2.2 SITE DESCRIPTION 3

2.3 PROPOSED DEVELOPMENT 3

3 CONCEPTUAL MODEL 4

3.1 SOURCES 4

3.2 RECEPTORS 4

3.3 PATHWAYS 5

3.4 SUMMARY 5

4 HUMAN HEALTH ASSESSMENT MODELLING 6

4.1 METHODOLOGY 6

4.2 SOURCE CHARACTERISTICS 6

4.3 PATHWAY CHARACTERISTICS 6

4.4 RECEPTOR EXPOSURE CHARACTERISTICS 8

4.5 RESULTS FROM INITIAL BASE MODELS 11

4.6 SENSITIVITY ANALYSIS 12

4.7 FINAL MODEL 18

5 SUMMARY AND RECOMMENDATIONS 20

5.1 DETAILED HUMAN HEALTH RISK ASSESSMENT 20

5.2 CONCLUSIONS 20

6 REFERENCES 21

Tables

TABLE 3.1: SUMMARY OF IDENTIFIED SITE-WIDE IMPACTS (HUMAN HEALTH) 4

TABLE 3.2: POTENTIALLY SIGNIFICANT POLLUTANT LINKAGES 5

TABLE 4.1: UNSATURATED ZONE INPUT PARAMETERS 7

TABLE 4.2: BUILDING PARAMETERS 7

TABLE 4.3: LAND USE AND RECEPTOR DATA - SCHOOL STUDENT 9

TABLE 4.4: LAND USE AND RECEPTOR DATA - SCHOOL TEACHER 9

TABLE 4.5: LAND USE AND RECEPTOR DATA – GROUNDSKEEPER/CARETAKER 10

TABLE 4.6: LAND USE AND RECEPTOR DATA – COMMUNITY USE 11

TABLE 4.7: SUMMARY OF RECEPTOR TARGET VALUES FOR THE BASE MODELS 12

TABLE 4.8: SENSITIVITY ANALYSIS – SCHOOL STUDENT 13

TABLE 4.9: SENSITIVITY ANALYSIS – GROUNDSKEEPER/CARETAKER 14

TABLE 4.10: SENSITIVITY ANALYSIS – COMMUNITY SPORTS FIELD USER 15

TABLE 4.11: SUMMARY OF RECEPTOR TARGET VALUES FOR THE BASE MODELS 17

TABLE 4.12: CONTAMINANT PATHWAYS 17

TABLE 4.13: SCHOOL STUDENT (11-16YRS) 18

TABLE 4.14: FINAL MODEL SSAC 18


5311 E DQRA 1A Contents

Appendices

Appendix A: Drawings

5311/E/002: Proposed Site Layout Plan

5311/E/003: Current Site Layout

5989/E/004: Conceptual Site Model

NLC-STA-DRG-C-316: Proposed Formation Level Isopachyte Contours

Figure 2.1: Site Location Plan

Appendix B: Correspondence with North Lanarkshire Council / WSP

Appendix C: CLEA Model Chemical Input Parameters

Appendix D: CLEA Model Outputs


5311 E DQRA 1A Page 1

1 INTRODUCTION

Ramboll UK Ltd (RUK) has been commissioned by Balfour Beatty to undertake a

detailed quantitative assessment to assess the risks to human health from

benzo(a)pyrene and benzo(a)anthracene contamination identified at the proposed St

Ambrose school site.

This work follows on from a recommendation made in the ground contamination

Generic Quantitative Risk Assessment report completed by RUK (Ref. Ground

Contamination Risk Assessment, November 2009), and should be read in conjunction

with this report.

1.1 Background

The proposed site for St. Ambrose High School, Coatbridge has previously been used

as Townhead Landfill site which was operational from 1945-1972. At present the site

lies north of Drumpellier Country Park and is used as community playing fields.

In order to progress the proposed development the site needs to be established as

suitable for use as a school considering the potential contaminative impacts present

on site associated with its historical use as a landfill site.

Ramboll UK understand 1No. desk study (Phase I) and 2No. intrusive site

investigations (Phase II) have been undertaken within the site boundary since 2005;

available reports and investigations for the site are outlined below:


- Preliminary Ground Investigation Report, St. Ambrose High School,

Coatbridge (URS, 2006);

- Proposed St. Ambrose High School, Ground Investigation Report (URS,

2008); and


A review of these reports was undertaken by WSP (2009) on behalf of North

Lanarkshire Council’s Environmental Department and is detailed in the letters

outlined below and provided in Appendix B:

- Report Review – Proposed St. Ambrose High School, WSP 17th November

2008;

- Proposed St. Ambrose, Townhead Report Review Summary and

Recommendations, Environmental Services 18th November 2008 (incl. URS

response to comments); and


Additional investigation works supervised by Ramboll were undertaken by

Geotechnics Ltd. in 2009 to supplement the existing site data and provide additional

information across the site. This data was then used to provide a robust ground

contamination risk assessment for the proposed St. Ambrose School, addressing the

concerns raised by WSP (2009). This additional work is detailed in the following

report:

- Ground Contamination Risk Assessment Report (RUK, 2009)

This Generic Quantitative Risk Assessment (RUK, 2009) concluded that the site is

suitable for redevelopment with regards to Human Health as long as the following

recommendations are adhered to:

1. Limited remediation (e.g. excavation and disposal of localised areas of

elevated contaminants should further validation testing prove these materials

are unsuitable for reuse) and further detailed quantitative risk assessment;



2. Incorporation of specific design measures (e.g. gas protection measures to

mitigate risks posed by ground gases); and

3. Risk management during development (e.g. development of an environmental

specification and a watching brief during development to validate

conformance to the environmental specification).

This report addresses the requirement for further detailed risk assessment identified

in point one above.

1.2 Aims and Scope of Works

The aim of this report is to assess further the potential risks to human health from

benzo-a-pyrene and benzo-a-anthracene identified as potential contaminants of

concern and to provide recommendations regarding the suitability of the site for the

proposed school development with respect to these two contaminants. In addition

recommendations will be provided regarding the suitability of material to be reused

on site during site re-profiling works.

The works to be completed to achieve these aims are:

• Develop site specific conceptual model for the proposed school;

• Complete detailed risk assessment modelling for risks to human health from

contaminants identified in the GQRA report and provide site specific

assessment criteria for the contaminants of concern;

• Review site data using the site specific assessment criteria to determine

suitability of material for proposed site development; and

• Provide recommendations regarding suitability of the site for its proposed use

and recommendations for material management during site works.


This report has been prepared for the exclusive use of Balfour Beatty for the purpose

of assisting site evaluation in the context of the proposed redevelopment at the time

of writing. This report should not be used in whole or in part by any third parties

without the express permission of Ramboll UK Ltd. in writing.

Ramboll has endeavoured to assess all information provided to them during this

appraisal. This report summarises information provided from a number of external

sources and cannot offer any guarantees or warranties for the completeness or

accuracy of information relied upon.



2 SITE DETAILS

The site of the proposed St. Ambrose High School is located in Coatbridge,

Lanarkshire. A site location plan is presented as Figure 2.1 in Appendix A.

2.1 Site Location

The site is located off Townhead Road and is bordered by Townhead Road to the

north, a community centre, pavilion and residential properties to the east,

Drumpellier Park to the south and a Golf Course to the west.

The site is located at the approximate National Grid Reference (NGR) 271546,

665970.


The site is described in detail within the Ground Contamination Risk Assessment

Report (RUK, 2009) and summarised below.

The site covers an area of approximately 13.5Ha. Currently the site is occupied by

numerous sports pitches and is in use by the general public as a recreational area.

An area of car parking and an access road is present in the northeast of the site.

A current site layout plan indicating current topographic levels is included in

Appendix A as Drawing 5311/E/003.

2.3 Proposed Development

The proposed development at Townhead Road, Coatbridge, will comprise the

construction of St. Ambrose High School including a two-storey school building with

associated school pitches, car parking, play areas and soft landscaping.

A plan showing the proposed development layout is presented as Drawing No.

5311/E/002 in Appendix A.

Proposed areas of cut and fill at the time of writing are shown on Drawing No. NLC-

STA-DRG-C-316 in Appendix A.



3 CONCEPTUAL MODEL

Previous site investigations and assessment provided in RUK 2009 have identified

elevated concentrations of contaminants which may pose an unacceptable risk to

human health at the site based on the proposed development.

For a risk of pollution or environmental harm to occur as a result of ground

contamination, all of the following elements must be present:

• A source, i.e. a substance that is capable of causing pollution or harm;

• A receptor (or target), i.e. something which could be adversely affected by

the contaminant; and

• A pathway, i.e. a route by which the contaminant can reach the receptor.

If one of these elements is missing there can be no significant risk. If all are present

then the magnitude of the risk is a function of the magnitude and mobility of the

source, the sensitivity of the receptor and the nature of the migration pathway.

A detailed conceptual model of the St Ambrose site is developed in this section to

identify sources, pathways and receptors and thus identify plausible pollutant

linkages. The conceptual model has been developed considering the proposed cut

and fill works and concentrations of contaminants reported are considered to be

representative of material that will be within the top 1m following re-profiling across

the site.

This assessment is being completed to address potential risks to human health from

benzo(a)pyrene and benzo(a)anthracene only, for risks to other potential receptors

from other contaminants refer to RUK Ground Contamination Risk Assessment

Report (2009).

3.1 Sources

The contaminants identified at elevated concentrations in the GQRA (RUK, 2009)

which may present a risk to human health are summarised in Table 3.1 below,

(taken from Table 5.2 and Table 5.3 from RUK 2009).

Table 3.1: Summary of Identified Site-Wide Impacts (Human Health)

Determinand

Generic Assessment Criteria

GAC (mg/kg)

Maximum concentration

(mg/kg)

95th %UCL

(excluding outliers) (mg/kg)

Statistical Outliers

Topsoil

Benzo(a)pyrene 1 7.8 5.43 None

Benzo(a)anthracene 6.2 14 8.61 None

Landfill Material

Benzo(a)pyrene 1 9.4 2.31 None

3.2 Receptors

The site is being developed primarily as a secondary school for children of ages 11-

18years. It is understood that the south-eastern part of the school building and the

sports pitches will also be used as a community sports facility during weekends. It is

assumed that this weekend use would be for children and adults of all ages. In

addition, there is a public right of way through the centre of the site which is

considered likely to be used on a daily basis by dog walkers for example.

The human health receptors at this site based on the proposed site use are

therefore:

• School students who will attend the school on a regular basis.

• Teachers who will attend the school on a regular basis.



• Groundskeeper/caretaker assumed to attend the school during standard

working hours and also to provide access at weekends.

• Dog walkers assumed to use the right of way through the centre of the site

on a daily basis.

• Children and adults of all ages using the playing fields and south-eastern part

of the school building as a community sports facility at weekends.

3.3 Pathways

Pathways are the means by which a contaminant can reach a receptor. Active

pathways are dependent on the physical characteristics of the source compounds,

the site and surrounding area between the source and receptor.

The nature of the site surface affects the potential for direct contact between site

users and the impacted soils. The proposed development layout in Drawing

5311/E/002 indicates areas of soft landscaping and sports pitches where site users

may come into direct contact with the soils. Material will be brought onto site as a

make-up for all the sports pitches, however, as a worst case for this assessment; it

is considered that site soils will be used for the sports pitches. Direct contact

pathways will not be active in areas beneath the building footprint and hardstanding.

There is a potential for volatilisation and migration of contaminants which may pose

a risks in particular in indoor spaces. Although the source contaminants are not

considered highly volatile, volatilisation and inhalation are considered as active

pathways.

The following pathways will therefore potentially be active with regards to human

health:

• Ingestion of soil /dusts;

• Dermal contact with soil; and

• Volatilisation, vapour migration and inhalation.

3.4 Summary

The pollutant linkages identified as potential significant are shown in Table 3.5

below.

Table 3.2: Potentially significant pollutant linkages

Source Pathway Receptors

Benzo(a)pyrene Benzo(a)anthracene

Ingestion of soils/dusts

Dermal contact with soils

Inhalation of vapours

11-18 year old student

Adult teacher

Groundskeeper /caretaker

Dog walkers

Weekend users of community facilities

Further site specific human health risk assessment modelling has therefore been

undertaken to provide a more site specific assessment of the significance of the

identified pollutant linkages.

An updated Site Conceptual Model is provided as Drawing 5311/E/003, Appendix A.



4 HUMAN HEALTH ASSESSMENT MODELLING

The generic assessment undertaken by RUK (2009), assessed the site in relation to

generic criteria for a residential end use without home-grown produce. As

demonstrated in the conceptual model developed in Section 3, the site is highly unlikely

to be used in a manner similar to the standard residential scenario, therefore the initial

assessment is considered to be highly conservative.

The aim of this detailed quantitative modelling is reduce uncertainty and to modify

conservative assumptions made at the GQRA stage to provide a more site specific

assessment of risks to future site users under conditions most likely to be encountered

during the use of the site following the proposed development.

4.1 Methodology

RUK has carried out detailed human health risk assessment using CLEA v1.06 (EA,

2009) to generate Site Specific Assessment Criteria (SSAC) for the compounds of

concern.

A number of contaminant specific and site specific input parameters are required to

define the environmental conditions and nature of the receptors at the site, and thus

quantify the site conceptual model. These are discussed in the sections below.

Due to the uncertainty in the receptor exposure models, a detailed sensitivity

analysis has been undertaken to assess the significance of the input parameters for

the different models completed and thus identify the critical receptors.

4.2 Source Characteristics

The source impacts considered within this study are:

• Benzo(a)pyrene

• Benzo(a)anthracene

Toxicity and chemical characteristics

For each compound, toxicological health criteria values are required to define

minimal risk levels and various chemical properties are required to define likely

contaminant partitioning and transport. These values have been sourced for each

compound in accordance with the UK guidance on the hierarchy of authoritative data

sources detailed in SR2 (EA 2009). All input values are presented in Appendix C with

references.

Bioavailability

Bioavailability is defined as the fraction of the chemical that can be absorbed by the

body.

As no site specific data is available for the site, a worst case estimate of 100%

bioavailability is used within the base model assessment, however this is likely to be

conservative for the source compounds identified.

4.3 Pathway Characteristics

The following pathways are potentially active with regards to human health:

• Ingestion of soil /dusts.

• Dermal contact with soil.

• Volatilisation, vapour migration and inhalation.



The ingestion, dermal contact and inhalation elements of these pathways are defined

through the receptor exposure characteristics (detailed in Section 4.4).

However in order to estimate a concentration of the contaminants in air, fate and

transport modelling is required to determine volatilisation and migration through the

unsaturated zone into a building or outdoor air space.

Parameters must therefore be defined to quantify the unsaturated zone through

which contaminants will migrate and also the indoor and outdoor airspaces in which

vapours may build up.

Unsaturated zone characteristics

The unsaturated zone predominantly comprises Made Ground; including sandy silt

topsoil and slightly clayey sandy gravel and gravelly sand strata.

For simplicity of modelling and assessment and to allow for potential variability of

Made Ground in each locality, a single ‘typical’ shallow Made Ground material has

been quantified as a typical sandy silt loam to reflect the topsoil which is the most

heavily impacted source material.

Table 4.1 below details the unsaturated zone input parameters used and reference

for each.

Table 4.1: Unsaturated zone input parameters

Parameter Value used in model

Reference

Soil type Sandy silt

loam

Default parameters within CLEA model used

for soil type.

Soil Organic Matter 15% Average of site values for shallow soils

pH 7.8 Average of site values for shallow soils

Building parameters

Building parameters are required to assess potential vapour intrusion and

accumulation within the proposed buildings. These parameters determine vapour

concentrations in the indoor air space and thus the receptor point exposure

concentration indoors.

The building parameters are estimated based on the proposed layout at the time of

writing. In the absence of site specific data, parameters are generally selected based

on the CLEA typical commercial office building as it is considered that this will be the

most similar generic building type to the proposed school building. Table 4.2 below

details the input parameters used and justification for each.

Table 4.2: Building parameters

Parameter Value used

in model Units Reference

Building footprint 10,000 m2 Approximate area of proposed school

building

Living space air exchange

rate 1 hr-1

Typical estimate for office and

warehouse buildings. (SR3 EA 2009).



Parameter Value used in model

Units Reference

Living space height above

ground 3.0 m Estimate for school building

Living space height below

ground 0 m No basements proposed

Pressure difference 5.1 Pa Assumed similar to standard commercial

office building (SR3 EA 2009).

Foundation thickness 0.275 m Proposed slab thickness

Floor crack area 1980 cm2 Assumed similar to standard commercial


Dust loading factor 100 µg m3 Assumed similar to standard commercial


Default soil gas ingress

rate 150 cm3 s-1

Assumed similar to standard commercial


4.4 Receptor Exposure Characteristics

5No. main potential human receptor groups have been identified for the proposed St

Ambrose school site: students, teachers, groundskeepers, dog walkers and users of

the community facilities.

In order to complete the detailed modelling assessment, the critical receptor needs

to be identified, i.e. the user of the site most likely to be affected by the impacts

identified. This will depend mainly on the age of the receptor, frequency of the site

use and activities on site. The 5 main receptors are discussed in brief below:

1. The 11-18year old student is considered likely to be more susceptible than

adults working at the school but only over a maximum period of 7 years at

school.

2. The adult teachers will be less susceptible to impacts than the younger

students but are potentially at risk for a much longer duration assuming a

worst case full working lifetime.

3. The activity patterns of typical adult groundskeepers/caretakers is uncertain,

however given the use of the facility at weekends as well as during the school

week there is a potential that an adult may frequent the site on a daily basis

through the week for security and maintenance of school and grounds and

also briefly at weekends to allow access to the appropriate facilities.

4. Dog walkers using the right of way through the site are considered most likely

to use the path daily but only to walk through and not spend a significant

amount of time on the site. The right of way runs adjacent to the school

building and as such will mostly be across hardstanding areas where contact

with the site soil will be minimal. It is therefore considered very unlikely that

this user group will be a critical receptor. Dog walkers will therefore not be

considered further within this assessment.

5. Users of the community sports facilities are assumed to be children and adults

of all ages, using the facility for community sports club training and matches

and interschool sports matches.

It is unclear at this stage which user group will be the critical receptor at this site

therefore 4 different exposures models are defined.



Parameters quantifying the receptor and exposure pathways must be defined for

each of the receptor models. These are discussed for each receptor group in the

following sections. These parameters are used for the reasonable worst case base

assessment models on which to perform the sensitivity analysis.

4.4.1 11-18yr old student

It is assumed that a student will be at the school for 7 years from age 11 to 18 years

old. However, CLEA defines age classes at yearly intervals up to the age of 16 then

a single age class for 16-65 year olds. In order to provide a conservative model for

the school students therefore, only the 11-16 year old age classes are modelled.

Table 4.3 below details the input parameters used and justification for each.

Table 4.3: Land Use and receptor Data - School Student

Parameter Value Reference

Exposure Frequency

(days/year) 190 Standard school year.

Occupancy Period

Indoors (hours) 7

Estimate based on 5 hours per day

indoors and 2 hours per day outdoors

through the basic school day (ECETOC

2001). An additional 2 hours indoors per

day has been included for extracurricular

activities and/or after school club assumed

as a worst case for the minority of

students.

Occupancy Period

Outdoors (hours) 2

No ingestion rates or soil-skin adherence factors specific to school pupils could be

sourced. These parameters are therefore defined for each age class based on data

from CLEA v. 1.06.

The air dispersion factors and the fraction of the site with hard or vegetative cover

are based on a standard commercial building as this is considered the closest in size

to the proposed school building and site area.

4.4.2 Adult Teacher

It is assumed that an adult teacher will attend the school on a standard term time

basis for a worst case full working lifetime.


Table 4.4: Land Use and receptor Data - School Teacher


Exposure Frequency

(days/year) 195

Standard school year, including standard 5

teacher days in addition to the 190 days the

students attend.

Occupancy Period

Indoors (hours) 7

Estimate based on 5 hours per day indoors

and 2 hours per day outdoors through the

basic school day (ECETOC 2001). An

additional 2 hours indoors per day has been

included for supervision of extracurricular

activities and/or after school meetings as a

worst case for the minority of teachers.

Occupancy Period

Outdoors (hours) 2



No ingestion rates or soil-skin adherence factors specific to teachers could be

sourced. These parameters are therefore defined for the age class based on the

standard commercial worker model data from CLEA v. 1.06.




4.4.3 Groundskeeper/caretaker

The activity patterns of typical adult groundskeepers/caretakers are uncertain,

however given the use of the facility at weekends there is a potential that an adult

may frequent the site on a daily basis through the week for security and

maintenance of school and grounds and also briefly at weekends to allow access to

the appropriate facilities.


Table 4.5: Land Use and receptor Data – Groundskeeper/caretaker


Exposure Frequency

(days/year) 230

Assuming a standard working year at full

time assuming daily exposure to outdoor

pathways (SR3, EA 2009). An allowance for

additional weekend visits has not been

included as these are most likely to be short

and thus cannot be modelled within the

same model as the full time working hours.

Occupancy Period

Indoors (hours) 4.5

Standard working day for a commercial

worker as per SR3, EA 2009 assuming a

45hour working week. Occupancy Period

Outdoors (hours) 4.5

The values in the table above do not provide an ideal model of likely exposure

frequency/duration but will be considered further within the sensitivity analysis.

No ingestion rates specific to groundskeepers/ caretakers could be sourced.

However, the soil-skin adherence factors defined for a standard commercial worker

are based on a groundskeeper (SR3, EA 2009) therefore these parameters are

defined for the age class as per a standard commercial scenario, based on data from

SR3 (EA, 2009).




4.4.4 Users of community facilities

Users of the community sports facilities are assumed to be children and adults of all

ages, using the facility for community sports club training and matches and

interschool sports matches. The critical users within this group are again unclear

prior to modelling. Two scenarios have been modelled, one assuming very young

children of primary school age (4-11 year olds) attending weekly sports clubs and a

second scenario assuming secondary school children attending sports clubs twice a

week.




Table 4.6: Land Use and receptor Data – Community Use


a. 4-11 year old

Exposure Frequency

(days/year) 39

Assuming 1 occasion per week during term

time (39 weeks).

Soil-skin adherence

factor outdoor

(mg cm-2 day-1)

1 Residential scenario used as worst case.

Occupancy Period

Indoors (hours) 0.5

Estimate based on:

Indoor time assumed 0.5 hour for

changing/washing etc.

Outdoor assumed to include either warm-up

and match or training.

A review of after-school sports clubs has

been undertaken and typically, training

sessions for children aged 4-11yrs are 1hr

long (see list of school links in references)

Occupancy Period

Outdoors (hours) 1

b. 11-16 year old

Exposure Frequency

(days/year) 78

Assuming 2 occasions per week during term

time (39 weeks).

Soil-skin adherence

factor outdoor

(mg cm-2 day-1)

0.6 Estimate based on rugby player (USEPA

2004).

Occupancy Period

Indoors (hours) 0.5

Estimate based on:

Indoor time assumed 0.5 hour for

changing/washing etc.

Outdoor assumed to include either warm-up

and match or training.

A review of after-school sports clubs has

been undertaken and typically, training

sessions for children aged 11-16yrs are 1-

2hr long (see list of school links in

references)

Occupancy Period

Outdoors (hours) 2

No ingestion rates or indoor soil-skin adherence factors specific to sports fields could

be sourced. These parameters are therefore defined for the age class based on data

from SR3 EA2009.



to the proposed school building and site area, taking into account the height of the

receptor.

4.5 Results from initial base models

Table 4.7 below summarises the site specific assessment criteria (SSAC) derived for

each compound for each of the receptor groups.



Table 4.7: Summary of receptor target values for the base models

Compound

Site Specific Assessment Criteria (mg/kg)

School student

Adult Teacher

Adult Groundskeeper

4-11 yr old community

user

11-16yr old community

user

Benzo(a)pyrene 12 16 14 23 38

Benzo(a)anthracene 82 110 95 160 260

There are a number of uncertain parameters involved in the derivation of these SSAC

in particular for the groundskeepers and community use. A sensitivity analysis has

been completed below to assess the significance of this uncertainty and allow a

reasonable final model to be selected as the critical receptor and final SSAC for the

site.

4.6 Sensitivity Analysis

A sensitivity analysis has been undertaken for each receptor group, detailed in the

sections below. The sensitivity analysis has been completed using benzo(a)pyrene as

the most critical contaminant identified on site.

The age classes for each receptor group have been defined based on the critical

users within the group. Parameters for each age class are defined within the CLEA

software and science reports. No alterations to these standard UK parameters have

been made.

For each receptor group (with the exception of the community use outdoor scenario),

no specific ingestion rates or soil-skin adherence factors could be sourced. These

parameters were all therefore defined for each age class based on data within CLEA

v. 1.06. These parameters are not included within the sensitivity analysis as they

are defined from the most appropriate UK guidance available.



to the proposed school building and site area. These parameters are not included

within the sensitivity analysis as they are defined from the most appropriate UK

guidance available.

Uncertain parameters are discussed and reasonable final model inputs selected.

4.6.1 School student and teacher

The only uncertain and variable parameters within these models are the occupancy

times and exposure frequency. Although the exposure frequency is set at 190

days/year for pupils and 195 days/year for teachers as the standard UK school year,

the pitches are proposed to be used by the community outside school hours.

Therefore it is likely that a student who attends the school may return at weekends

for sports activities.

The attendance on site during weekends is likely to be of limited duration perhaps

only a maximum of 3hrs per weekend for a training session and sports match. This

additional site time is difficult to model within the CLEA model as the number of

hours per day is set the same for each day attending site. To try and allow for this

extra time on site, an estimate of total hours per year on site has been made

assuming the standard school year along with an additional allowance for short

weekend visits. This has then been adapted into 2 models, one adding the extra site

time onto the standard school days (i.e. 190 days/per year at an extended

occupancy period) and a second model assuming reasonable maximum number of



days attendance with the total hours on site divided by this extended exposure

frequency.

The student model is more conservative than the teacher model as the occupancy

period is the same variable for both models, only the student model has therefore

been considered further within the sensitivity analysis.

A summary of the analysis for the school student receptor is provided in Table 4.8

below detailing the range of input parameters and the effect of altering each on the

resultant SSAC. The Base Model SSAC was 12mg/kg.

Table 4.8: Sensitivity Analysis – School Student

Parameter Base model

Range Resultant SSAC

for range

(mg/kg)

Reference

Occupancy

Period

(hours/day)

7 hrs

indoors,

2hrs

outdoors

5hrs

indoors,

2hrs

outdoors

13

Base model: 5 hours per day

indoors and 2 hours per day

outdoors through the basic school

day (ECETOC 2001) plus an

additional 2 hours indoors per day

for after school clubs.

Range:

5hrs indoors, 2hrs outdoors -

ECETOC 2001 guidance with no

after school allowance;

5hrs indoors, 4hrs outdoors –

ECETOC 2001 guidance plus an

additional 2hrs outdoors

9 hours indoors as worst case.

9hrs

indoors 11

5hrs

indoors,

4hrs

outdoors

13

Exposure

Frequency

(days/year)

and

Occupancy

Period

(hours/day)

190

days/yr

with

7hrs

indoors,

2hrs

outdoors

190

days/yr

with

7.3hrs

indoors

and

2.5hrs

outdoors*

12

Base model: Assuming the

standard UK school year

Range:

Assuming additional weekend

visits of 3hrs (2hrs outdoors, 1hr

indoors) once a week throughout

the year. Total hours/yr =

190daysx9hrs +52daysx3hrs =

1866 hours/yr (assuming

1382hrs/yr indoors, 484hrs/yr

outdoors).

A. 190 days at 9.8hours/day

(1866hrs/yr divided by 190 days)

- including 7.3hrs/day indoors,

2.5hrs/day outdoors.

B. 242days at 7.7hours/day

(1866hrs/yr divided by 242 days)

– including 5.7hrs/day indoors,

2hrs/day outdoors.

242

days/yr

with

5.7hrs

indoors

and 2hrs

outdoors*

10

*assuming 7hrs indoors and 2hrs outdoors during a school day and 1hr indoors, 2hrs outdoors during a weekend visit as an assumed worst case

The occupancy period alone makes limited difference to the SSAC.

The variations in exposure frequency and occupancy period based on the potential

for a student at the school to attend a weekend leisure visit have slightly reduced the



SSAC when considering the maximum number of days attendance. The base model

of 9hrs per day over the standard term time of 190days is considered reasonable for

the student receptor. However, it is possible that a high proportion of children who

attend the school and live in the local community will attend weekly sports classes

during term times and holidays. Therefore it is considered more appropriate for the

final model to consider the school student who also attends a sports class once every

weekend throughout the year to add a degree of conservatism. The more

conservative of the two scenarios modelled will be adopted as the final model.

4.6.2 Groundskeeper/Caretaker

No specific time activity data has been identified for school groundskeepers and as

such the nature and duration of activities are highly uncertain.

It is assumed that as a minimum a groundskeeper/caretaker will be employed for a

standard working year of 230 days/year, 9 hours per day as defined for a standard

UK commercial worker (SR3 EA, 2009). It is considered highly unlikely that a

groundskeeper would be working longer hours than this thus 9 hours is considered a

conservative maximum for the length of the working day.

Given that the site is to be used at weekends as well as during the working week, it

is possible that a groundskeeper may also have responsibility for attending site to

provide access to facilities for club use at the weekend. This attendance on site is

likely to be of limited duration perhaps only a maximum of half an hour each day.

This additional site time is difficult to model within the CLEA model as the number of

hours per day is set the same for each day attending site. To try and allow for this

extra time on site, an estimate of total hours per year on site has been made

assuming the standard working year along with an additional allowance for short

weekend visits. This has then be adapted into 2 models, one adding the extra site

time onto the standard working days (i.e. 230 days/per year at an extended

occupancy period) and a second model assuming reasonable maximum number of

days attendance with the total hours on site divided by this extended exposure

frequency.

A summary of the analysis is provided in Table 4.9 below detailing the range of input

parameters and the effect of altering each on the resultant SSAC. The Base Model

SSAC was 14mg/kg.

Table 4.9: Sensitivity Analysis – Groundskeeper/Caretaker



for range

(mg/kg)

Reference

Occupancy

Period

(hours/day)

4.5hrs

indoors,

4.5hrs

outdoors

6hrs

indoors,

3hrs

outdoors

14

Base model: Standard 9 hour

working day (EA 2009) with

estimated split of 50%indoor,

50%outdoor.

Range: indoor/outdoor time

varied to 1/3indoors, 2/3outdoors

and 2/3 indoors, 1/3outdoors

3hrs

indoors,

6hrs

outdoors

15





for range

(mg/kg)

Reference

Exposure

Frequency

(days/year)

and

Occupancy

Period

(hours/day)

230

with

4.5hrs

indoors,

4.5hrs

outdoors

269d/yr

with

7.8hours/

day

13

Base model: Standard working

year at full time, assuming daily

exposure to outdoor pathways

and standard 9 hour day,

estimated split of 50%indoor,

50%outdoor.

Range:

Assuming additional term time

weekend visits of 0.5hr once a

week. Total hours/yr =

230daysx9hrs +39daysx0.5hrs =

2090 hours/yr.

A. 269 days at 7.8hours/day

(2090hrs/yr divided by 269 days).

B. 230days at 9.1hours/day

(2090hrs/yr divided by 230 days).

230d/yr

with

9.1hours/

day

14

Occupancy period and exposure frequency makes only a minor difference to the

SSAC. Although the increased exposure frequency is likely to represent a worst-case

estimate of exposure for this receptor group, this is considered to be an overly-

conservative estimation of exposure time.

The base model is considered to have a reasonable degree of conservatism built in

through the long working day assumed. The base model inputs will therefore be

maintained for the final SSAC model.

4.6.3 Users of community facilities

The critical users within this group and activity patterns are unclear and as such, two

scenarios were modelled, one assuming primary school age children (4-11 year olds)

attending weekly sports clubs and a second scenario assuming secondary school

children attending sports clubs twice a week.

The main variables for these models are the exposure frequency (e.g. No of training

session/matches per week), occupancy period (how much time is spent on site

indoors and outdoors during each visit) and the outdoor soil-skin adherence factor.

A summary of the analysis is provided in Table 4.10 below detailing the range of

input parameters and the effect of altering each on the resultant SSAC.

Table 4.10: Sensitivity Analysis – Community Sports Field User

Parameter Base

model Range

Resultant SSAC for range (mg/kg)

Reference

4-11 yr old (Base Model SSAC = 23mg/kg)

Exposure

Frequency

(days/year)

39

52 17 Base model: assumed once a

week during term time.

Range:

52 – once per week throughout

the year;

78 –twice per week during term

time;

104 – twice per week throughout

the year.

78 12

104 8.7





for range

(mg/kg)

Reference

Soil-skin

adherence

factor outdoor (mg cm-2 day-1)

1

0.6 27 Base model: Residential scenario

used as worst case.

Range:

0.6 - rugby player (USEPA 2004);

0.3 - soccer player (USEPA 2004). 0.3 31

Occupancy

Period

(hours/day)

0.5hr

indoors,

1hr

outdoors

0.5hr

indoors,

2hr

outdoors

22

Base model: based on typical

lengths of after-school sports

activities following a review of UK

Primary School sports

programmes.

Range: 2hr outdoor considered

maximum likely for training or

sports match for this age group.

11-16 yr old (Base Model SSAC = 38mg/kg)

Exposure

Frequency

(days/year)

78

39 76

Base model: assumed twice a

week during term time.

Range: based on typical practises

per week of after-school sports

activities following a review of UK

Secondary School sports

programmes

39 - once a week during term

time;

52 – once a week throughout the

year;

104 – twice per week throughout

the year;

117 – three times per week

during term time.

52 57

104 28

117 25

Soil-skin

adherence

factor outdoor (mg cm-2 day-1)

0.6

1 for age

class 12,

0.3 for

age

classes

13-16

43

Base model: rugby player (USEPA

2004).

Range:

1 and 0.3 - standard residential

values for age classes (SR3

EA2009);

0.3 - soccer player (USEPA 2004). 0.3 48

Occupancy

Period

(hours/day)

0.5hr

indoors,

2hr

outdoors

0.5hr

indoors,

3hr

outdoor

38

Base model: estimate for this age

group.

Range: 3hr outdoor considered

maximum likely for training plus a

sports match.

In completing the sensitivity analysis process it is clear that the 4-11 year receptor

group is the more sensitive of the two age groups modelled. The 11-16 year will

therefore not be discussed further.

Occupancy period makes only a minor difference to the SSAC. The base model input

is considered a reasonable exposure assumption for the age group and as such will

be retained in the final model.

The soil to skin adherence factor makes a significant difference to the model. The

base model input is considered over conservative for the proposed use of the site,



however in the absence of any other age and activity specific guidance, the

conservative end of the range will be retained for the final models.

The main influence on the model output is the exposure frequency. The base model

of 1 visit per week during term time is considered reasonable for the 4-11yr old

receptor as at this age it is considered unlikely that more frequent off-site trips

(away from their own primary school) will be made for organised activities. It is

possible that children may also visit the site during holidays however, thus a

frequency of once a week throughout the year may be more appropriate and will be

used for the final models to add a degree of conservatism.

4.6.4 Summary of Sensitivity Analysis

The sensitivity analysis has shown the most uncertain and sensitive parameter for

most models to be the exposure frequency. This is reasonably well defined for the

basic student and teacher models but is harder to define within the CLEA model for

possible short duration additional weekend exposure.

Minor amendments are considered appropriate to the previously defined base models

to provide an estimate of reasonable maximum exposure for each receptor. These

changes are detailed in 4.6.1-4.6.3 above and the SSAC derived using the final

models for each receptor are summarised in Table 4.11 below. The final model

output sheets from CLEA v1.06 are provided in Appendix D.

Table 4.11: Summary of receptor target values for the base models

Compound

Site Specific Assessment Criteria (mg/kg)

School student

Adult Teacher

Adult Groundskeeper

4-11 yr old community

user


Benzo(a)anthracene 69 110 95 120

The school student has been identified as the most conservative of the receptor

groups.

The sensitivity analysis was completed for benzo(a)pyrene only. In order to confirm

that this analysis is appropriate for the other contaminants of concern, the

%contribution to the SSAC from each pathway has been assessed. The sensitivity

analysis can be assumed appropriate for all contaminants with similar pathway

contributions. Table 4.12 below compares the pathways for each of the

contaminants of concern for the school student model.

Table 4.12: Contaminant Pathways

Pathway (%) Benzo(a)anthracene Benzo(a)pyrene

Soil ingestion 54.5 54.5

Dermal indoor 1.65 1.65

Dermal outdoor 43.8 43.8

Inhalation of dust (indoor and outdoor)

0.03 0.03

Inhalation of vapour (indoor and outdoor)

0.06 0.05



Soil ingestion is the dominant pathway for both benzo(a)pyrene and

benzo(a)anthracene. Therefore the relative sensitivity of parameters identified for

benzo(a)pyrene will be the same as that identified for benzo(a)anthracene.

The most sensitive receptor exposure scenario identified is the Student Model 2.

CLEA v. 1.06 models used in this assessment are included in Appendix D.

4.7 Final Model

Based on the sensitivity analysis and model runs described above, the most

sensitive, realistic exposure scenario is considered to be the student receptor who

visits the site every weekend to attend a sports class. This model has been selected

as the final model for specification of site specific assessment criteria for the material

at St. Ambrose.

Table 4.13 below details the final model exposure parameters used for the most

sensitive receptor at the site.

Table 4.13: School Student (11-16yrs)

Parameter Value used in

Model Units Reference

Exposure frequency 242 events/

year

Assuming school student and user of the

sports facilities for 1 visit per week.

Occupancy Period 5.7 indoors

2 outdoors hours

Standard school day (ECETOC, 2001)

with an additional 2hrs per day indoors

to allow for extracurricular activities.

Soil ingestion rates 0.1 (AC 12)

0.05 (AC 13-16) g/day SR3, EA 2009

Adherence of soil to

skin (outdoor)

1 (AC 12)

0.3 (AC 13-16)

mg/cm2

day-1 SR3, EA 2009

Adherence of soil to

skin (indoor) 0.06

mg/cm2

day-1 SR3, EA 2009

Table 4.14 below shows the site specific assessment criteria (SSAC) derived using

the final model parameters in comparison to the representative site concentrations

(95th percentile from each stratum) for each contaminant of concern at St. Ambrose.

The CLEA model output sheets are provided in Appendix D.

Table 4.14: Final model SSAC

Compound SSAC (mg/kg)

Representative site concentrations (mg/kg)

Topsoils Landfill

Materials

Benzo(a)pyrene 10 5.4 2.3

Benzo(a)anthracene 69 8.6 2.6



None of the representative site concentrations exceed the SSAC. Based on the

available data it is therefore considered unlikely that the material at the St. Ambrose

site will pose a significant risk to human health if the site is developed as a school as

per current proposals.



5 SUMMARY AND RECOMMENDATIONS

Impacts were identified during the GQRA (RUK 2009) which were considered to pose

a possible risk to human health based on the proposed development of the site as a

high school with associated sports pitches, soft landscaping and car parking.

Elevated concentrations of benzo(a)pyrene were identified in the topsoil and landfill

material across the site and elevated concentrations of benzo(a)anthracene were

identified in the topsoil material.

5.1 Detailed Human Health Risk Assessment

A detailed human health exposure assessment has been carried out to assess the

potential significance of these elevated compounds in soil in relation to the proposed

use of the St. Ambrose site.

Not only will the site be used as a school for students aged 11-18yrs, the sports

pitches will also be available for organised community use and there will be a right of

way through the school grounds for the general public. Therefore, there are

uncertainties in the likely user exposure at this site. Variability of exposure has been

considered within a detailed sensitivity analysis for different receptor groups and

different exposure scenarios for each group.

The assessment and sensitivity analysis indicates that a school student, who also

attends a sports class each week, is likely to be the critical receptor. This frequent

exposure model was identified as the most conservative of the estimated exposure

models. This model is considered to present a reasonable maximum exposure

scenario for likely user exposure to impacted soils at the site; this includes for, inter

alia, teachers, community site users and groundskeepers.

5.2 Conclusions

The reasonable worst case exposure model has calculated site specific assessment

criteria (SSAC) as detailed in Table 4.14

None of the representative site concentrations of benzo(a)pyrene or

benzo(a)anthracene from the St. Ambrose site exceed these SSAC. This suggests

that, based on the assumptions made in the development of the conceptual site

model and existing chemical data reported; the St. Ambrose site would be suitable

for use as a school with community facilities to be used by the general public within

the context of the scenarios modelled. The SSAC developed are considered suitable

for all uses and areas of the site thus there will be no specific material management

precautions required with regards to benzo(a)pyrene or benzo(a)anthracene.

However, the recommendations made in the Generic Quantitative Risk Assessment

(RUK, 2009) should also be adhered to in order to ensure any residual risks to

Human Health are mitigated. These recommendations include:

1. Limited remediation (e.g. excavation and disposal of localised areas of

elevated inorganic contaminants should further validation testing prove these

materials are unsuitable for reuse);

2. Incorporation of specific design measures (e.g. gas protection measures to

mitigate risks posed by ground gases); and

3. Risk management during development (e.g. development of an environmental

specification and a watching brief during development to validate

conformance to the environmental specification).



6 REFERENCES

BRE 2004. Cover Systems For Land Regeneration.

DEFRA and the Environment Agency, 2002 TOX2 Contaminants in soil: updated

collation of toxicological data and intake values for humans. Benzo(a)pyrene

SC050021/TOX1 (April, 2002)

ECETOC 2001 Exposure Factors Sourcebook for European Populations (with focus on

UK Data) Technical Report No. 79

Environment Agency, 2009a SR2 Human Health toxicological assessment of

contaminants in soil SC050021/SR2 (January 2009)

Environment Agency, 2009b SR3 Updated technical background to the CLEA model

SC050021/SR3 (January 2009)

Environment Agency, 2009c SR4 CLEA Software (Version 1.05) Handbook

SC050021/SR4 (September 2009)

Environment Agency, 2009d CLEA Software (Version 1.06) (September 2009)

USEPA, 2004a Additional and current dermal absorption fraction values for soil

(ABSd) (Supplementing Exhibit 3-4 of Part E) [online]

Available from www.epa.gov/oswer/riskassessment/ragse/index.htm

USEPA, 2004b Risk Assessment Guidance For Superfund Volume 1: Human Health

Evaluation Manual (Part E, Supplemental Guidance For Dermal Risk Assessment).

Interim Review Draft For Public Comment, EPA/540/R/99/005.

School Links:

A review of various after-school sports programmes for children of Primary School

(4-11yrs) and High School (11-16yrs) ages was undertaken to establish the typical

frequency and duration of after-school sports activities. This list is not exhaustive.

Gospel Oak Primary School, London

http://www.gospeloak.camden.sch.uk/parents/clubs/clubs.htm

Woodlands Community College, Derby

http://www.woodlands.southampton.sch.uk/school/extracurricular_students.html

Harefield Primary School, Southampton

http://www.harefield-pri.southampton.sch.uk/school/index/htm

Bitterne Manor Primary School, Southampton

http://www.bitternmanor.southampton.scho.uk/school/clubs/htm

Regents Park Community College, Hampshire

http://www.regentsparkcollege.org.uk/folders/curriculum/physical_education_amp_d

ance/extra_curricular_timetable/

Redbridge Community High School

http://www.school-portal.co.uk/GroupHomepage.asp?GroupID=52681

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