BRINDLE STREET, PRESTON GEO-ENVIRONMENTAL...

BRINDLE STREET, PRESTON GEO-ENVIRONMENTAL ASSESSMENT FINAL R1126/07/3088 MAY 2007

Geo-Environmental Assessment, Brindle Street, Preston Report No: R1126/07/3088

Celtic, May 2007 Somic Plc

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Client: Somic Plc Report Number: R1126/07/3088 Report Title: Geo-Environmental Assessment Report Status: Final Author(s): C.Wood (Signature & Date) ______________________________ Project Manager: C. Butler-Duncliffe (Signature & Date) ______________________________ QA Approved: J. Freeman (Signature & Date) ______________________________

Celtic is the trading name for Celtic Technologies Ltd. This report has been prepared for Somic Plc by Celtic with reasonable skill, care and diligence and taking account of the contract terms and conditions and manpower and resources devoted to it in agreement with the client. Celtic disclaims any responsibility to the client and others in respect of any matters outside the scope of the above. The report is only valid when it is used in its entirety. This report is confidential to the client and Celtic accepts no responsibility to third parties to whom the report, or any part thereof, is made known. Any such party using any information contained within the report does so at their own risk.



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CONTENTS 1.0 INTRODUCTION ........................................................................................................................................1

2.0 SITE DESCRIPTION ..................................................................................................................................2 2.1 GENERAL .......................................................................................................................................... 2 2.2 ENVIRONMENTAL SETTING .............................................................................................................. 2 2.3 INTRUSIVE INVESTIGATION REQUIREMENTS.................................................................................... 2 2.4 SAMPLING PLAN ............................................................................................................................... 2

3.0 FIELDWORK...............................................................................................................................................4 3.1 GENERAL .......................................................................................................................................... 4 3.2 WINDOW SAMPLE PROBEHOLES....................................................................................................... 4 3.3 FIELD MONITORING.......................................................................................................................... 4

4.0 LABORATORY TESTING ........................................................................................................................5 4.1 CHEMICAL CONTAMINATION TESTING............................................................................................. 5

5.0 GROUND CONDITIONS ...........................................................................................................................6 5.1 GENERAL .......................................................................................................................................... 6 5.2 MADE GROUND ................................................................................................................................ 6 5.3 GLACIAL DEPOSITS........................................................................................................................... 6 5.4 GROUNDWATER................................................................................................................................ 6 5.5 VISUAL/OLFACTORY EVIDENCE OF CONTAMINATION..................................................................... 6

6.0 ENGINEERING CONSIDERATIONS .....................................................................................................7 6.1 GENERAL .......................................................................................................................................... 7 6.2 FOUNDATION ASSESSMENT .............................................................................................................. 7 6.3 FLOOR SLABS ................................................................................................................................... 8 6.4 GENERAL CONSTRUCTION ADVICE .................................................................................................. 8 6.5 ROAD PAVEMENT ASSESSMENT ....................................................................................................... 9 6.6 GROUND GAS ASSESSMENT ............................................................................................................. 9

7.0 CHEMICAL TESTING RESULTS .........................................................................................................11 7.1 GENERAL ........................................................................................................................................ 11 7.2 PUBLISHED GUIDELINES................................................................................................................. 11 7.3 HUMAN HEALTH RISK ASSESSMENT OF INORGANIC CONTAMINANTS .......................................... 12 7.4 LEACHATE TEST RESULTS.............................................................................................................. 15 7.5 GROUNDWATER TEST RESULTS ..................................................................................................... 15 7.6 SUMMARY OF THE RISK ASSESSMENT............................................................................................ 16

8.0 OUTLINE REMEDIAL AND RECLAMATION ACTION PLAN.....................................................17 8.1 INTRODUCTION ............................................................................................................................... 17 8.2 ENVIRONMENTAL REQUIREMENTS................................................................................................. 17 8.3 OUTLINE RECLAMATION PROPOSALS............................................................................................. 18

TABLES TABLE 1 – SUMMARY OF DESK STUDY INFORMATION..................................................................................................2 TABLE 2 NHBC TRAFFIC LIGHT SYSTEM (CIRIA 659). ..............................................................................................9 TABLE 3 - RESULTS FOR PAH SOIL CONCENTRATIONS ..............................................................................................15 APPENDICES A DRAWINGS B EXPLORATORY HOLE LOGS

(i) DYNAMIC CONTINUOUS SAMPLING BOREHOLES C LABORATORY TEST RESULTS

(i) CHEMICAL TEST RESULTS (ii) ENGINEERING TEST RESULTS

D GROUND GAS RESULTS


Celtic, May 2007 1 Somic Plc

1.0 INTRODUCTION

1.1 In January 2007, Celtic Technologies Ltd (Celtic) was instructed by Mr Richard Blackburn of Somic Plc, to undertake an intrusive site investigation of a site (i.e. an active mill) located on Brindle Street, Preston. A desk study of the site was submitted to the client in March 2007 (Celtic Report Ref. R1126/07/3084). The assessment made in this report is partially based on the information obtained during the desk study.

1.2 This report has been prepared following an intrusive site investigation which took place between the 12th and 14th February 2007. A program of ground gas monitoring was undertaken between the 26th February and 23rd March 2007 at the site. The investigation has been designed to provide a geo-environmental and geotechnical report of the site and devise an outline remedial and reclamation action plan for an assumed redevelopment to residential with gardens end-use. Thus, the report contains details on site logistics, fieldwork, engineering and contamination laboratory testing; ground gas and ground water monitoring; and an interpretative assessment of the ground conditions.

1.3 The following report is confidential and written solely for the benefit of the Client, Celtic and the Client’s representatives and agents. Celtic warrants the findings of the report based on ground conditions and results of the subsequent analysis and monitoring at the time of the investigation. Additional information, improved practices, new guidance, changes in legislation or provision of detailed layout and design proposals will necessitate this report having to be reviewed in whole or in part after that date. There may be special conditions appertaining to the site, however, which have not been revealed by the investigation which would not have been taken into account in this report.

1.4 It should be appreciated, however, that any desk study information is not necessarily exhaustive and that further information relevant to the proposed site usage may be available. The accuracy of any map extracts obtained through Envirocheck and other sources cannot be guaranteed and therefore, it should be recognised that different conditions on site may have existed between and subsequent to the various map surveys.

1.5 Whilst the report may express an opinion on possible configurations of strata (between or beyond the exploratory holes) or possible presence of features (based on either visual, verbal or published evidence); such an assessment is guidance only and no liability can be accepted for its accuracy. The comments on ground conditions are based on observations made at the time of the investigation, unless otherwise stated. It should be noted, however, that ground water levels vary due to seasonal or other effects.

1.6 It should also be noted, that any ground gases and contaminants monitored and analysed for are those most likely to give rise to the principal hazards for the proposed use of the site. However, no liability can be accepted for the presence of contaminants, explosive or toxic gases not analysed for.

1.7 Any qualitative risk assessment included in this report considers the significance of any contamination based on generic standards for the stated end use, together with an assessment of the presence of a pollutant linkage between sources, pathways and receptors. A qualitative assessment of low or insignificant risk does not imply that elevated concentrations of various determinands are not present compared to background or ‘green field’ conditions. A different assessment may apply if a different end use were proposed. It should also be acknowledged that institutional bodies may consider the presence of ‘contaminants’ in other ways regardless of whether an apparent risk is present based on defined sources, pathways and receptors.



2.0 SITE DESCRIPTION

2.1 General

2.1.1 The site is located to the north of New Hall Lane within Preston town centre (approximately SD 5510 2982) as shown in the Site Location Plan, Figure A1. The site covers approximately 1.3 ha and is currently an active mill (occupied by Somic Plc.) who manufacture spun woven/braided products and plastic coated fabric products. The site is relatively level with a surface covering of concrete and/or tarmacadam. A brick lined reservoir (depth c. 3.0 m bgl) exists in the north-west area of the site and an adjacent raised area (consisting of an infilled former reservoir) has a sparse covering of vegetation.

2.1.2 The site is part-bound to the south by residential properties (fronting onto Stefano Road); whilst, the remainder being bound by Stefano Road. A mixture of commercial/industrial properties bound the site to the north, east and west. For an appreciation of the site layout, see Drawing Ref. D1126/3088-A2, Appendix A.

2.2 Environmental Setting

2.2.1 A Desk Study for the site has been produced by Celtic (Report Ref. R1126/07/3084). The findings of the desk study are summarised in Table 1 (below)

Table 1 – Summary of Desk Study Information

Site History Site occupied (approx.100 years) by the current textile manufacturing mill. Site layout has remained largely unchanged with exception of former infilled reservoirs in the north-west area of the site (infilled in the 1950s/1960’s).

Geology Underlain by Made Ground, glacial deposits and Triassic sandstone. Hydrogeology Hydrology

Sandstone classified as major aquifer. Site partially lies within Zone 3 of the Source Protection Zone. A industrial abstraction well is present on-site which is used for industrial cooling purposes. Nearest watercourse (the River Ribble) is located 1,000m south.

Potential Contaminant Sources

Made Ground, especially infill to former reservoirs; hydrocarbons associated with (two) below ground fuel storage tanks, south of site; migration of ground gas from sources areas.

2.3 Intrusive Investigation Requirements

2.3.1 The Desk Study identified that the following information would be required to quantify the relevance and severity of pollutant linkages at the site:

• Actual presence and extent of contaminants in soils; • Leachability of contaminants from soils; • Presence of low permeable clay barrier to the underlying major aquifer; • Generation of ground gas.

2.4 Sampling Plan

2.4.1 Information collated during the site research was used to develop an understanding of the likely contaminants present, sources and likely spatial distribution. The present and historical site setting was identified and targeted sampling plan proposed accordingly, which comprised:

• Targeted area in the surrounding below ground storage tanks;



• Targeted area of the former reservoirs; • Spread of boreholes over the remaining area of the site to assess general site

conditions.



3.0 FIELDWORK

3.1 General

3.1.1 Probeholes were drilled across the site to examine the ground conditions. The locations of the exploratory holes were chosen in order to investigate the ground conditions across the site, in light of available access and avoidance of underground services; and to determine the presence of any of the Potential Contaminants of Concern (PCoC).

3.1.2 Fieldwork was generally carried out in accordance with BS5930 (1999), “Code of Practice for Site Investigations”, and BS10175 (2001), “Investigation of Potentially Contaminated Sites - Code of Practice” (Association of Geo-technical and Geo-environmental Specialist Guidelines for Good Practice in Site Investigations, August 1998) and supervised by an experienced Geologist.

3.2 Window Sample Probeholes

3.2.1 Thirteen window sample probeholes (WS1 to WS13) were drilled at the site from the 12th to the 14th February 2007. A concrete coring rig was required at all locations to penetrate through the concrete hard standing. The approximate locations of the boreholes are show in Drawing D1126/3088-A2, Appendix A.

3.2.2 The boreholes were advanced using a Terrier 2002 window sampling rig to bore 100mm diameter boreholes to approximately 3.00 m below ground level (bgl). Soils were sampled from various depths to allow examination, soil logging and laboratory testing. Descriptions and depths of the various strata recovered are presented on the borehole records, reproduced in Appendix B. In Situ Standard Cone Penetration Tests (CPTs) were undertaken in five of the boreholes (WS03, WS05, WS07 and WS10) to provide a measure of the relative density of the underlying geology; no logs were produced for these positions.

3.2.3 A number of boreholes (WS01, WS02, WS04, WS05, WS12 and WS13) were utilised for installation of soil gas/groundwater monitoring standpipes, on completion of drilling. A visual representation of the standpipes is presented on the relevant borehole logs. The remaining 7 boreholes were backfilled with site arisings/bentonite.

3.3 Field Monitoring

3.3.1 Ground gas/groundwater level monitoring was carried out on three occasions, on the 26th February, 14th and 22nd March 2007. The standpipes were monitored for methane, carbon dioxide, and oxygen, atmospheric pressure and flow using a Geotechnical Instruments Infra Red Gas Analyser and Gas Data (GF60) Analyser. The results of the gas concentration measurements, gas flow readings and groundwater level data are presented in Appendix D.

3.3.2 Following measurement of soil gas concentrations and gas flow readings, the valve head assembly was removed to allow measurement of groundwater levels. A shallow groundwater sample was recovered (on the 14th March 2007) from one borehole location (WS04); and deeper groundwater was sampled from a deeper abstraction BGS borehole ((SD 552 298, Appendix B) from the underlying Triassic Sandstone Aquifer (on the 15th February 2007) for analytical testing.



4.0 LABORATORY TESTING

4.1 Chemical Contamination Testing

4.1.1 Laboratory testing of the Made Ground and naturally occurring soils was scheduled by Celtic and was undertaken by a UKAS accredited laboratory, in accordance with MCERTS accreditation standards. The samples were analysed for some or all of the following determinands:-

• Arsenic, barium, beryllium, boron, cadmium, chromium, copper, lead, mercury, nickel, selenium, vanadium, zinc

• pH • Total Cyanide • Organic Carbon • Phenol (total) • Alcohols • Speciated Poly-Aromatic Hydrocarbons (PAH) • Speciated Volatile Organic Compounds (VOC) and Semi-Volatile Organic

Compounds (SVOC) • Volatile Petroleum Hydrocarbons (VPH) and BTEX • Extractable Petroleum Hydrocarbons (EPH)

4.1.2 In addition, two soil samples were scheduled for leachability testing for Total Petroleum Hydrocarbons (TPH), BTEX and MTBE.

4.1.3 Two groundwater samples were analysed for all of the following determinands:-

• Semi-Volatile Organic Compunds (VOC) • Dissolved arsenic, barium, beryllium, boron, cadmium, chromium, copper, lead,

mercury, nickel, selenium, vanadium, zinc. • pH • Electrical conductivity • Biological Oxygen Demand (BOD) after 5 days attenuation • Speciated Poly-Aromatic Hydrocarbons (PAH) • Volatile Petroleum Hydrocarbons (VPH) and BTEX • Extractable Petroleum Hydrocarbons (EPH)



5.0 GROUND CONDITIONS

5.1 General

5.1.1 Based on published geological information it was anticipated that the ground conditions across the site would comprise of Glacial Till deposits overlying the Sherwood Sandstone Group. From 1849 onwards, historical land use (from the Desk Study) indicated that Made Ground materials could potentially be present at the site.

5.2 Made Ground

5.2.1 Made Ground materials were encountered across the site to a depth of 0.20m and 0.80m bgl, with thicker Made Ground being generally encountered in the southern and north eastern areas. In general, the Made Ground comprised of clinker, gravels, and brick fragments.

5.3 Glacial Deposits

5.3.1 Underlying the Made Ground materials, Glacial Till (Boulder Clay) was encountered within all boreholes (with the exceptions of WS04 and WS09) and proven to the base of each borehole (to a depth of approximately 3.00m bgl).

5.3.2 The Glacial Deposits comprised predominantly soft to very stiff clays and sandy clays, with pockets of organic clays. The base of the Glacial Till deposits was not proven during the investigation.

5.4 Groundwater

5.4.1 Groundwater strikes were recorded within one borehole, (WS04) during its formation, at a depth of 0.40m within the Made Ground. This is likely to represent perched ground water within the Made Ground materials.

5.5 Visual/Olfactory Evidence of Contamination

5.5.1 During the investigation, no hydrocarbon odours were noted within Made Ground materials or the Boulder Clay. An organic odour was noted within the clay deposits in WS06 (at a depth of between 0.70m and 1.2m bgl) and in WS11 (at a depth of between 1.00m and 1.60m bgl).



6.0 ENGINEERING CONSIDERATIONS

6.1 General

6.1.1 As discussed within the Desk Study, information obtained from the Envirocheck stated the site was not in the influence of coal mining or mining instability; or potential for compressible or collapsible ground. The site is also considered to be within an area of very low risk from landslide ground stability hazards or shrinkage/swelling clay ground stability hazards.

6.1.2 Geological records for the BGS borehole (SD 552 298 reported in the Desk Study Report) confirm Glacial Deposits overlie Glacial Till deposits to a depth of 21 m bgl (above the Sherwood Sandstone). Exploratory holes have confirmed the published geological records Glacial Deposits (Boulder Clay) over Glacial Till. Made Ground (0.3 – 2.7 m bgl) which was poorly compacted and locally void was found to overlie natural stratum.

6.1.3 Beneath the Made Ground, stiff clay was encountered to 3 m bgl. Soft clays were encountered to 1.0 m bgl; typically comprised of soft fine (black-organic) clays or sandy clay (N=2.5 and N=5) and intermediate shrinkage potential; advancing into more competent firm clays below 2.5 m bgl (with N = 45 and N=50).

6.1.4 Natural moisture contents, wet densities and plastic indices values are presented in Appendix E. Consistency limit values of shallower soils show intermediate plasticity (Wp > 35%) in soils.

6.2 Foundation Assessment

6.2.1 The Made Ground materials are not considered suitable for founding conventional shallow spread or trench fill footings, in their current state as they would be subject to unacceptable total and differential settlement from the upper ground; which may potentially leading to structural stress.

6.2.2 It is considered for any proposed low-rise development that lightly reinforced strip or shallow spread foundations could be utilised within the Glacial Deposits at a minimum depth of 1.5m to 2.0m bgl (within the sandy clay) to an allowable bearing pressure of 100 kN/m² to limit total settlements to less than 25 mm. Locally foundations may have to be deepened and placed below any existing deeper Made Ground or soft or loose materials.

6.2.3 Where foundations span across varying strata, such footings could be subject to differential settlement which may potentially leading to structural distress. Consideration should be given to inclusion of mesh reinforcement top and bottom of the foundation to span across the interface between the different strata types to extend at least 1m either side. This should reduce the potential for differential settlement to occur.

6.2.4 It is recommended that foundations would need to be re-evaluated as part of the remediation proposals for the site. Should higher loads be required (i.e. several storey apartment block design), and if ground levels are not susceptible altered, it is recommended that foundations would need to be re-evaluated as part of the remediation proposals for the site. If ground levels at the site are reduced, load bearing from foundations can be supported on more competent ground (as indicated from the SPT values).



6.3 Floor Slabs

6.3.1 Given that the ground is poorly compacted, the adoption of a ground bearing floor is considered unsuitable. It is therefore recommended that the ground floor be suspended. If a ground bearing floor slab is the preferred option, we would recommend that the Made Ground is removed and re-engineered (if confirmed to be suitable) in suitably compacted layers or replaced with a granular fill.

6.4 General Construction Advice

Exploratory Hole Positions

6.4.1 Boreholes carried out as part of this or previous investigations may represent soft spots and conduits/sumps for groundwater or surface water. In excavations, such materials may also be loose and unstable. Unless specifically stated, exploratory hole locations should be regarded as approximate. Consideration should be given to accurate location of such features where it is considered that they may impact on the proposed development.

Excavation Stability/Hazardous Gases

6.4.2 The Made Ground may be subject to spalling and partial collapse within excavations. Deeper excavations may also be prone to rapid, unpredictable, large scale collapse, particularly in the presence of groundwater inflows. Consequently, temporary support should be considered for all excavations where collapse is to be avoided. Heavier duty closed shoring should be provided for any excavation where man entry is necessary, in compliance with statutory requirements to ensure safe working conditions.

6.4.3 Low levels of carbon dioxide and carbon monoxide have been recorded across the site during the monitoring visits, hence care should be taken when personnel enter excavations (or confined spaces), to ensure full ventilation is available and appropriate safety precautions taken.

Classification of Buried Concrete

6.4.4 The results of chemical analyses undertaken on samples recovered from the Made Ground and naturally occurring deposits encountered at the site indicate the Design Sulphate Class for the site to be “DS 1” based on the results of water soluble sulphate (50-110 mg/L) and reference to BRE Special Digest 1 “Concrete in aggressive ground”, Part I, in association with pH values (pH.> 6.5). The BRE Digest suggests that buried concrete should be designed to Aggressive Chemical Environment for Concrete (ACEC) site classification being “AC-1.”



6.5 Road Pavement Assessment

6.5.1 It is recommended that road pavement design should be based on an equilibrium design value of 2% for any formation within the Made Ground and 3% for any formation within natural deposits, based on the material properties, without the benefit of re-engineering the fills. It is recommended that proof rolling of the formation is carried out and any soft, loose, compressible or otherwise unsuitable deposits removed and replaced with a suitable fill compacted in appropriate layers. It is considered that the deposits at formation level are likely to be frost susceptible and appropriate precautions should be taken with regard to road pavement design such as allowing at least 450mm of non frost susceptible material between formation and finished road level. It is recommended that a protective cover layer is left above the formation until the road construction is carried out to prevent deterioration of the sub grade.

6.6 Ground Gas Assessment

6.6.1 Ground gas monitoring has been undertaken as part of this investigation between 26th February and 22nd March 2007 with a total of three monitoring visits being undertaken, the results of which are included below.

6.6.2 Currently, there are no statutory threshold limits in the UK for hazardous gases in the ground for low-rise housing with gardens. However, the CIRIA 659 publication (in 2007) details a risk based approach based on the Wilson and Card ‘Reliability and Risk in Gas Protection Design’ for the identification of gas protection for a low-rise housing development by comparing the measured gas emission rates to generic ‘Traffic Lights.’ In Table 2, Typical Maximum Concentrations (TMC) are provided under the Traffic Lights for initial ground gas screening purposes and risk-based Gas Screening Values (GSVs) for consideration for situations where these maximum concentrations are exceeded. These calculations should be carried out for both methane and carbon dioxide and the worse case adopted in order to establish the appropriate protection measures.

Table 2 NHBC Traffic Light System (CIRIA 659). Methane1 Carbon Dioxide1

Traffic

Light

Typical maximum

concentration

(% v/v)

Gas screening value

(GSV)1,2

(L/hr)

Typical maximum

concentration

(% v/v)

GSV 2

(L/hr)

Green

Amber 1

Amber 2

1 0.16 5 0.78

5 0.63 10 1.56

20 1.56 30 3.13

1. Generic GSVs are based on guidance contained within latest revision of Department of the Environment and the Welsh Office (2004 edition) “The Building Regulations: Approved Document C” and used a sub-floor void of 150mm thickness; 2. The GSV, in litres per hour, is as defined in Wilson and Card (1999) as the bore hole flow rate multiplied by the concentration in the air stream of the particular gas being considered.

6.6.3 The worst ground gas scenario is based on highest concentrations of monitored methane or



carbon dioxide levels are screened against the ‘Traffic Light’ and GSV in the risk assessment. In certain circumstances, however, the TMC concentrations can be exceeded on the basis of professional judgement and understanding of the site specific gas-regime (where monitoring in the worst temporal conditions has occurred) and the conceptual site model.

6.6.4 The method used to develop the GSVs is based on a number of assumptions regarding the proposed structures, and designers should also ensure that these assumptions are appropriate to their site. It is important to recognise that the GSV is only a guideline value and not an absolute threshold. Thus, the GSV quoted in the table above can be exceeded in certain circumstances with completion of a detailed gas risk assessment taking into account the site-specific conditions.

6.6.5 Site monitoring has shown that carbon dioxide concentrations varied between 0.1% and 10.9% by volume in boreholes at positive gas flow rates from 2.6 l/hr to 6.4 l/hr (as detailed in Appendix D). Highest concentrations of carbon dioxide were recorded within borehole WS13, south-east of the mill (i.e. dye room).

6.6.6 In accordance with recommendations documented in CIRIA 659, a risk assessment from carbon dioxide ground gas for this borehole (which represents a site-specific worst case scenario) was made as presented in Appendix D. This risk assessment indicate that the derived gas screening values (GSV) range from 0.07 to 0.28 l/hr with a worst case flow of rate of 6.4 L/hr. Thus, the GSV of 0.28 L/hr and carbon dioxide concentration of 10.9%, in the worst case scenario will characterise the site as ‘Amber 1’ in the ‘Traffic Light’ risk derived system.

6.6.7 However, the maximum carbon dioxide is marginally above the typical maximum concentration of 10% and hence consideration should be made on whether the site should be characterised as Amber 2. However, the monitoring programme has shown, with relative confidence, that recorded maximum gas concentrations and flow rate from the underlying (non -desiccated) natural clays is most unlikely to arise in elevated ground gas concentrations across the site. Based on this rationale, the site can be categorised of low to intermediate gas regime whereby low-level gas protection measures would be required. This would involve protection measures comprising a membrane and ventilated sub floor void to limit the ingress of gas into building (as prescribed in BRE Report 414).

6.6.8 Methane concentrations were typically less than <0.1% by volume during the various monitoring phases. A risk assessment from methane ground gas for this borehole, using maximum gas flow rates of 6.4 L/hr and maximum gas concentrations of 0.3% will indicate that a GSV of 0.019 L/hr occurs at this site. In this case, site specific methane concentrations are substantially below the typical maximum concentrations (of 1% v/v) and GSV (of 5 L/hr) for methane.



7.0 CHEMICAL TESTING RESULTS

7.1 General

7.1.1 An assessment of the chemical analyses of soils and groundwater, using comparative screening against available and relevant published guidelines in generic risk assessment are discussed in the following sections of the document.

7.2 Published Guidelines

7.2.1 Currently, there are no statutory limits in contaminant concentrations from ground or groundwater for human health risk assessment. However, there are a number of documents available, which provide guidelines values on acceptability screening. Those documents which are considered to be most relevant to this site are discussed below:

Human Health

7.2.2 DEFRA and The Environment Agency published a series of guidelines with regards to the assessment of risks to human health from land contamination. Within these guidelines (CLR7 to CLR10) a series of generic Soil Guideline Values (SGVs) have been produced for the following contaminants: arsenic, cadmium, chromium, lead, nickel, mercury, selenium, ethylbenzene, toluene and phenol (references CLR7 – 10 and CLEA model, March 2002). In this assessment, a land use of residential housing (with plant uptake) has been assumed.

7.2.3 Using the CLEA assumptions Atkins have derived screening values for a number of contaminants not currently covered by SGVs, these ATRISKSOIL human health soil screening values (for residential end-use) and at 1% soil organic matter (SOM) were used as guideline values for benzene, xylene and naphthalene concentrations in soil.

7.2.4 The proposed future land use of this site is unknown; however, residential end-use with plant uptake (from private gardens and landscaped areas) has been considered in this risk assessment as appropriate measures against future risk to human health. Screening against the CLEA SGVs are intended to be used as a guide to whether further assessment is required or whether remedial action should be taken at the site.

Phytotoxicity

7.2.5 In December 2002, DEFRA formally withdrew previous guideline values derived by the Interdepartmental Committee on the Redevelopment of Contaminated Land (ICRCL), commonly referred to as ICRCL 59/83 (1987) “Guidance on the Assessment and Redevelopment of Contaminated Land”. The ICRCL values presented were not considered suitable to assess the ‘significant possibility of significant harm to human health’ in the context of Part IIA of the Environmental Protection Act, and now have broadly been replaced by the DEFRA/EA Soil Guideline Values, as discussed above.

7.2.6 Within the ICRCL guidance document, Threshold Trigger Concentrations (TTC) for a limited number of contaminants that are considered to be potentially phytotoxic (toxic to plants) is documented. In the absence of alternative guidance for phytotoxicity, screening will be made against the relevant TTC values (from the currently withdrawn ICRCL documentation) to allow for initial assessment to be made of potential phytotoxic effects to plant growth from identified contaminant concentrations in the ground.



Controlled Waters

7.2.7 Controlled Waters are defined by Section 104 of Part III of the Water Resources Act, 1991, and amended by the Water Act 2003. This is interpreted to include:

‘all rivers, canals, lakes, groundwater, estuaries and coastal waters to three nautical miles from the shore. Groundwaters are defined as water contained in underground strata within the saturation zone, and includes saturated perched water bodies.’

7.2.8 Leachability testing of soils have been undertaken as an initial assessment of the potential risks to groundwater from impacted soils; and leachate concentrations compared to the UK Drinking Water Standards (DWS) on the basis that the site is underlain by a major aquifer (i.e. Sherwood Sandstone Group).

7.3 Human Health Risk Assessment of Inorganic Contaminants

7.3.1 A generic risk assessment using the available CLEA SGV’s and ICRCL (for phytotoxic metals) screening values are compared, where applicable, to analytical chemical concentrations. Results from chemical analysis of soils are recorded in Appendix C. In accordance with CLR7, statistical analyses of inorganic concentrations in soils were undertaken using the upper bound 95th Percentile (US95); and the mean and maximum value tests. A mean value test compares the SGV with the upper 95th percentile of the mean measured concentration.

7.3.2 Thus, concentrations which may need to be compared against remedial targets for the site area will be based on values determined from the 95th percentile concentrations of all concentrations (≤ 1 m depth) in soils sampled across the site. This approach is more conservative than using an average or median value assessment. The significance of the statistical analysis has been discussed in sections 7.3.3 to 7.3.8.

Human Health

7.3.3 No exceedances above the CLEA SGV’s guideline values were recorded for concentrations of chromium, mercury and selenium in samples from Made Ground and natural soils (i.e. Boulder Clay).

Human Health (arsenic)

7.3.4 Concentrations of arsenic above the SGV’s were recorded in two out of the six samples tested from materials less than 1.0 m bgl. The two samples which exceeded the trigger value of 20 mg/kg recorded values of 21 mg/kg and 82 mg/kg.

7.3.5 A statistical assessment has been carried out in line with CLR7 for arsenic using the mean and maximum tests on the results recorded within the top 1.0m of ground. Based on these results, the upper bound 95th percentile mean value of 34 mg/kg for arsenic does exceed the SGV and the maximum value of 82mg/kg is classified as an outlier, suggesting that statistically, concentrations of arsenic above the SGV may be encountered within the top 1.0m of ground across the site and therefore represent localised hotspots of contamination.



Human Health (nickel)

7.3.6 Of the six samples tested for nickel from the top 1.0m of ground, one of the results exceeded the SGV for a residential with plant up take end use of 50mg/kg from borehole WS08 at 0.5m bgl with a result of 67mg/kg.

7.3.7 The statistical assessment carried out in line with CLR7 for nickel concentrations in samples recovered from the top 1.0m of ground, using the mean value test on the results. The results indicate the upper bound 95th percentile geometric mean value of the results data did not exceed the SGV of 50 mg/kg. On the basis of these results, it is considered that the nickel concentrations within the top 1.0m of ground at the site do not pose a significant risk to future site users and residents.

Human Health (lead)

7.3.8 Only one sample out of six samples exceeded the SGV values (450mg/kg) for lead for residential end use with plant up-take. The sample showing this exceedance at concentrations of 760mg/kg was taken from WS12 (at 0.5m bgl).

7.3.9 The mean value test was carried out on lead from samples recovered from the upper 1.0 m of ground. The results had indicated that the upper bound 95th percentile geometric mean do not exceed the SGV of 450mg/kg. On the basis of these results, it is therefore reasonable to treat the mean value of (elevated) lead from this sample as belonging to the normal distribution lower lead concentrations (typically, below guideline values in the ground).

Human Health (cadmium)

7.3.10 Five out of six samples (from the upper 1.0 m of soil) tested for cadmium recorded cadmium concentrations < 0.5 mg/kg. The SGV for cadmium are pH based, thus, there is the potential that soils sampled from WS08 (at 0.5 mbgl) may show slight exceedance above the SGV (of 8 mg/kg at pH of 8) as pH values vary from 5.9 to 8.2 pH across the site.

7.3.11 A statistical assessment has been carried out in line with CLR7 for cadmium on samples recovered from the upper 1.0m of ground, using the mean value test on the results. The upper bound 95th percentile geometric mean value of the results do not exceed the lowest SGV of 1 mg/kg.

Phytotoxics (nickel, zinc and copper)

7.3.12 No samples tested for either copper and zinc (from the upper 1.0 mbgl) exceeded ICRCL trigger values; whilst four samples tested for nickel, zinc and copper from 1.0 m to 3.0 mbgl had exceeded the trigger values for phytotoxicity. Only one sample tested for nickel from the upper 1.0m of ground had exceeded the SGV values.

Phenols

7.3.13 Two samples were tested for total phenol concentrations recording concentrations below the detection limit (<0.1 mg/kg), thus, neither samples had shown exceedance above the SGV for phenol.

Cyanide (Total)

7.3.14 Neither DEFRA or the EA have published a methodology to assess short-term exposure to contaminants such as cyanide; therefore, concentrations in soils have been screened against



other relevant guidance. Reference to the DoE publication ‘Problems arising from the Redevelopment of Gas Works and Similar Sites’ published in 1987 on behalf of ICRCL identifies a concentration of 25 mg/kg as an appropriate guideline against short-term toxicity arising from cyanide ingestion. This guideline is conservatively based on the lower range of lethal dosage (of 2.5 g/kg) to a child (including a multiple risk factor of 100).

7.3.15 One sample was analysed for cyanide concentrations, and the results obtained show that concentrations did not exceed the above screening value.

Polycyclic Aromatic Hydrocarbons (PAHs)

7.3.16 Currently, there are no published SGVs for Total PAH or speciated PAH compounds. Thus, ATRISKSOIL screening values for naphthalene and benzo(a)pyrene were screened against the site concentrations for residential end-use. Seven samples were submitted for analysis of Polycyclic Aromatic Hydrocarbons (PAHs); and total PAH concentrations were recorded at values between 0.15mg/kg and 887.84mg/kg. A summary of these results are presented in the Table 3 (below).

7.3.17 Of the seven samples tested for naphthalene, two of the results exceeded the ATRISKSOIL screening values of 4.4 mg/kg for a residential end-use (with plant uptake), using a soil organic content of < 1%. These samples were sampled from borehole WS02 (at 0.5m bgl. and 1.5m bgl.) showing concentrations of 24 mg/kg and 14 mg/kg, respectively.

7.3.18 A statistical assessment has been carried out in line with CLR7 for naphthalene (from the results, below) using the mean and maximum value test. The results indicate that the maximum result is classified as an inlier and the upper bound 95th percentile mean value of 8.2mg/kg does not exceed the ATRISKSOIL screening values. On the basis of these results, it is considered that naphthalene concentrations within the ground do not pose a significant risk to future site users at the site.

7.3.19 For an end-use of residential with plant uptake, ATRISKSOIL screening values recommend that soil concentrations are less than 0.54 mg/kg benzo(a)pyrene for residential end-use. Three samples of soil which had shown exceedances above this guideline value as shown in Table 3.

7.3.20 A statistical assessment has been carried out (in line with CLR7) for benzo(a)pyrene soil concentrations using the mean and maximum value tests. The results indicate that the maximum result is classified as an inlier and the upper bound 95th percentile mean value of 53.0 mg/kg exceeds the ATRISKSOIL screening values of 0.54mg/kg.



Table 3 - Results for PAH Soil Concentrations Probehole Identification/ Sample Depth PAH

WS12 at

1.5m bgl WS13 at 0.5m bgl

WS02 at 0.5m bgl

WS02 at 1.5m bgl

WS04 at 0.5m bgl

WS06 at 0.8m bgl

WS08 at 0.5m bgl

Naphthalene <0.1 <0.1 24 14 0.55 <0.1 <0.1 Acenaphthylene <0.1 <0.1 0.19 0.14 <0.1 <0.1 <0.1 Acenaphthene <0.1 <0.1 22 16 0.52 <0.1 <0.1 Fluorene <0.1 <0.1 22 15 0.28 <0.1 <0.1 Phenanthrene <0.1 <0.1 190 140 2.9 <0.1 0.15 Anthracene <0.1 <0.1 43 29 0.57 <0.1 <0.1 Fluoranthene <0.1 <0.1 170 130 3.3 <0.1 <0.1 Pyrene <0.1 <0.1 140 100 2.6 <0.1 <0.1 Benzo(a)anthracene <0.1 <0.1 58 43 1.1 <0.1 <0.1 Chrysene <0.1 <0.1 62 45 1.2 <0.1 <0.1 Benzo(b)fluoranthrene <0.1 <0.1 51 37 1.3 <0.1 <0.1 Benzo(k)fluoranthrene <0.1 <0.1 19 14 0.49 <0.1 <0.1 Benzo(a)pyrene <0.1 <0.1 42 31 0.92 <0.1 <0.1 Dibenzo(a,h)anthracene <0.1 <0.1 4.9 3.7 <0.1 <0.1 <0.1 Benzo(g,h,i)perylene <0.1 <0.1 18 14 0.50 <0.1 <0.1 Indeno(1,2,3 cd)pyrene <0.1 <0.1 18 13 0.43 <0.1 <0.1 TOTAL <0.1 <0.1 887.84 642.75 16.79 <0.1 0.15

Notes: All data in mg/kg Total Petroleum Hydrocarbons (TPH)

7.3.21 Due to the presence of humic rich clay (at 1.5 to 2.0m bgl) in soils, targeted analysis of speciated Extractable Petroleum Hydrocarbons (EPH) over TPH was carried out at the site. The results gained from this generic risk assessment show an elevated presence of hydrocarbons (of the carbon fraction banding, C20-C30) in the locality of WS02.

7.4 Leachate Test Results

7.4.1 The results of the leachate testing have been compared to the UK Drinking Water Standards (DWS), Maximum Admissible Concentrations (MAC) as defined in the Water Supply (Water Quality) Regulations, 2000; and EQS Freshwater Standards in the absence of MAC.

7.4.2 The results from leachate data show no exceedance for determinants above the guideline values.

7.5 Groundwater Test Results

Organics

7.5.1 Groundwater data for BH1 show threshold TPH concentrations (<0.1mg/l) above the UK DWS standards (0.01mg/l), with VOC’s and PAH’s below analytical limits of detection.

Phenols

7.5.2 Phenol levels for BH1 were below analytical limits of detection (<0.01mg/l).

Inorganics

7.5.3 The groundwater sample from BH1 was analysed for a range of inorganics, including arsenic, lead, boron, mercury, nickel, zinc, copper, selenium, cadmium and chromium.



None of these determinands exceeded the UK DWS standards.

7.6 Summary of the Risk Assessment

7.6.1 Concentrations of arsenic, above CLEA SGVs guidelines (for residential endues) have been recorded from the Made Ground in locations of WS08 and WS12. However, concentrations appear to be associated with hot spots and are not statistically representative of typical concentrations in Made Ground across the site.

7.6.2 Nickel, zinc and copper concentrations in soils exceeded the ICRCL trigger values for phytotoxicity.

7.6.3 Benzo(a)pyrene has been identified in concentrations exceeding the ATRISKSOIL screening values in two boreholes, WS02 and WS04. The elevated TPH, naphthalene and benzo(a)pyrene (BaP) concentrations in the ground are synoptic with the proximity of probehole sampling to the underground storage tanks (UST), south of the site and indicative of perched hydrocarbon contamination in clays.



8.0 OUTLINE REMEDIAL AND RECLAMATION ACTION PLAN

8.1 Introduction

8.1.1 The risk assessment has indicated that residual soil contaminants of hydrocarbon origin are present in the southern and northern areas of the site. Impacted soils in these areas are identified as:

• Area 1: proximity to the current diesel UST’s

• Area 2: proximity to the back-filled former reservoir area.

The elevated TPH, naphthalene and benzo(a)pyrene (BaP) concentrations in the ground are synoptic with the proximity of probehole sampling to the underground storage tanks (UST), south of the site; and indicative of perched diesel hydrocarbon contamination in clays.

8.1.2 This following section of the report presents an outline remedial action plan that may

require modification once development proposals have been agreed. The proposals made here are general on the basis that the site will be redeveloped to residential with gardens end-use. Final site levels were not known at the time of writing this remedial action plan and therefore, some aspects of the following action plan may require re-appraisal once these final site levels are known.

8.2 Environmental Requirements

8.2.1 From the above discussions, it has been determined that the valid significant potential source-pathway-receptor pollutant linkages for this site are as follows:

• PAH contamination (i.e. BaP and naphthalene) on human health;

• Localised TPH concentrations in terms of human health.

8.2.2 Remedial requirements should be agreed with the local Council prior to works commencing on-site and are likely to comprise the following.

Validation of Conceptual Site Model

8.2.3 Access to the site during the investigation was limited by the existing use of the buildings. Following decommissioning and demolition, further site investigation across the site will be required to confirm the absence of contaminants under the building footprint.

Contaminant Hotspot Removal

8.2.4 Hotspots identified during the screening process around fuel tanks and the former reservoir will require further assessment and likely remedial action. Contaminated soils will need to be excavated chased out in each direction until the remedial target value is met. Base and side validation of any resultant excavation will need to be be undertaken to confirm concentration targets. Where the validation sampling fails to meet the remedial target value, further excavation will be required and the validation procedure repeated until the remedial target value is met.



8.2.5 Discussions with the regulatory authorities regarding appropriate remedial target values will be necessary prior to remedial works commencing.

Capping Layer

8.2.6 In order to sever the pathway between the pervasive contaminants at the site, it is recommended that a capping layer of a minimum of 600mm is incorporated into all garden and landscape areas.

8.2.7 All materials which comprise of the capping layer should be tested to ensure compliance with validation criteria which should be agreed with the Council. The quality of the material should be in accordance with BS3882 and the source certified as free of biological contaminants.

8.3 Outline Reclamation Proposals

Demolition and Earthworks

8.3.1 All earthworks operations should be carried out in accordance with the current Department of Transport specification for roads and bridges. Following an asbestos Type III survey, demolition should proceed in a manner to allow the full recovery of hard materials that when crushed can be re-used to form a stable and inert fill. Compaction requirements may vary across the site depending on foundation solutions.

8.3.2 All road formations should achieve a minimum CBR of 3%. All building bearing capacities should be to a minimum safe capacity of 50 kPa. All suitable materials should be crushed to DoT 6F2 grading and stockpiled for re-use. All ground-based obstructions (concrete, tarmacadam etc.) should be grubbed up to a depth of 1.5 m below the proposed formation/remediation level, or to greater depths where piling of new structures is proposed. All suitable arisings should be crushed to 6F2 and stockpiled for re-use.

8.3.3 Contaminated soils will be treated in accordance with the environmental requirements given above. Any movement of contaminated soils to temporary (stockpile) and permanent positions within the site will require the approval of the regulating authorities, and must acknowledge waste management requirements. Disposal of soils unsuitable for re-use on the site or surplus to requirements must be to licensed landfills, with the appropriate Duty of Care certification.

8.3.4 Any alteration in ground levels should be achieved by simple cut/fill processes to suit the proposed levels. Although it is not envisaged that there will be a need to import fills, if they are they should be suitable granular materials. Suitable crushed arisings will be used for the provision of a trenchfill platform. It is anticipated that there will be sufficient crushed arisings to also provide 300mm sub-formation to roads. Surplus crushed materials can also be used to provide a clean working platform, and form part of the permanent works elsewhere on the site. Garden soils will form part of the requisite 600mm environmental cover.

8.3.5 Site levels, drainage requirements and highway accesses will need to be determined for the site. If any alterations are to be made to levels across the site, it is most likely to involve raising levels in the north-west of the site (in the current reservoir areas). It is also likely that the developer will require formation/remediation levels to be 500mm approximately below



proposed slab and road levels to allow for the appropriate construction thicknesses and garden soils. Subject to drainage design requirements and layout needs, it may be possible to accommodate earthworks general volumetric requirements utilising materials arising from site; minimising the need for imported fills.

Services

8.3.6 The WRAS information and guidance note 9-04-03 sets out trigger concentrations for water supply pipes to be laid in contaminated land. Individual water companies may have their own trigger concentrations and advice should be sought. Where soil concentrations exceed the trigger values, special consideration of material selection or pipeline construction will be required.

8.3.7 In the case of metals and other inorganic substances, the trigger concentrations do not consider the risk to potable water in the pipes because there should be no risk of contaminants entering through joints as the water is under pressure. The values are set to protect staff working in an excavation. Typical requirements are to line the trench with an impermeable membrane and use clean backfill.

8.3.8 The values for organic substances are set to protect the water because they can permeate the plastic pipe walls. Note that in the more heavily contaminated sites, the water company may require site-specific consideration of the type of pipe and connections.

8.3.9 All water supply pipes (and other services) should be placed in ‘clean’ corridors possibly lined with a geotextile where the service passes through existing made ground and backfilled with inert material. The presence of organic substances on site is likely to require the use of protective pipe work for water supplies such as metallic pipes. It is recommended that the Water Supply Company is consulted with the chemical results for the site.



APPENDIX A

DRAWINGS

Project: Somic, Preston. Project No.: C1126

Client: Somic PLC.

Scale: NTSDate: May 07 Site Location – Figure A1

Scale: NTS

Date Drawn: April 2007

Title: D1126/3088-A2

Project: Somic PLC.

Client: Somic PLC.

Job No. C1126

Window Sample Location

WS01

Centrix HouseCrow Lane EastNewton le WillowsWarringtonWA12 9UY.



APPENDIX B

DYNAMIC CONTINUOUS SAMPLING BOREHOLES

Borehole Number:Date:

Method:

Project No:

Client:

Site Location:

Engineer: Easting:

Northing:

Datum:Hole Diameter:

Sheet: 1 of 1

Comments:

www.celtic-ltd.com

SUBSURFACE PROFILE SAMPLING/TESTING WELL

LVL

(mA

OD

)

Dep

th

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

Sym

bol

DESCRIPTION

Dep

th

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

Sam

ple

Ref

Sam

ple/

Test

Type

Sym

bol

N-V

alue

Wel

l Dat

a

WS0113-02-07

Window Sampling

C1126

Somic plc

Brindle Street, Preston

C Wood 0

0

100mm

0.000

-0.800

-1.100

-1.500

-2.100

-3.000

Ground SurfaceMADE GROUNDConcrete.MADE GROUNDBrick fragments, gravel and pebbles. No odour.Sandy CLAYBlack coarse sandy CLAY with frequent gravels.CLAYFirm light brown CLAY with occasional subrounded gravel.Sandy CLAYSoft light brown medium sandy CLAY with occasional rounded gravel.CLAYStiff light brown CLAY with occasional rounded gravel.

End of Borehole

WS01 /0.5mWS01 /0.7m

WS01 /2.0m

WS01 /3.0m


Method:

Project No:

Client:

Site Location:

Engineer: Easting:

Northing:


Sheet: 1 of 1

Comments:

www.celtic-ltd.com


LVL

(mA

OD

)

Dep

th

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

Sym

bol

DESCRIPTION

Dep

th

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

Sam

ple

Ref

Sam

ple/

Test

Type

Sym

bol

N-V

alue

Wel

l Dat

a

WS0213-02-07

Window Sampling

C1126

Somic plc


C Wood 0

0

100mm

0.000-0.240

-0.800

-1.100

-3.000

Ground SurfaceMADE GROUNDConcrete.MADE GROUNDBrick fragments, cobbles, pebbles and clinker. Sandy CLAYFirm black sandy CLAY with frequent gravels.CLAYLight brown CLAY with occasional gravel.

End of Borehole

WS02 /0.5m

WS02 /1.5m

WS02 /3.0m


Method:

Project No:

Client:

Site Location:

Engineer: Easting:

Northing:


Sheet: 1 of 1

Comments:

www.celtic-ltd.com


LVL

(mA

OD

)

Dep

th

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

Sym

bol

DESCRIPTION

Dep

th

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

Sam

ple

Ref

Sam

ple/

Test

Type

Sym

bol

N-V

alue

Wel

l Dat

a

WS0413-02-07

Window Sampling

C1126

Somic plc


C Wood 0

0

100mm

0.000

-0.500

-1.000

Ground SurfaceMADE GROUNDAsphalt.MADE GROUNDBrick fragments, gravel, cobbles and pebbles.NO RECOVERYNo recovery from 0.5 to 1.0m bgl.

End of Borehole

WS04 /0.5m

0.4m

No revocery from 0.5 to 1.0m bgl.


Method:

Project No:

Client:

Site Location:

Engineer: Easting:

Northing:


Sheet: 1 of 1

Comments:

www.celtic-ltd.com


LVL

(mA

OD

)

Dep

th

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

Sym

bol

DESCRIPTION

Dep

th

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

Sam

ple

Ref

Sam

ple/

Test

Type

Sym

bol

N-V

alue

Wel

l Dat

a

WS0613-02-07

Window Sampling

C1126

Somic plc


C Wood 0

0

100mm

0.000-0.200

-0.700

-1.200

-3.000

Ground SurfaceMADE GROUNDConcrete.CLAYStiff light brown CLAY with occasional gravel.CLAYSoft black CLAY - more organic.CLAYStiff light brown CLAY with occasional gravel. Sandy layer approximately 1.5m bgl.

End of Borehole

WS06 /0.5m

WS06 /2.5m


Method:

Project No:

Client:

Site Location:

Engineer: Easting:

Northing:


Sheet: 1 of 1

Comments:

www.celtic-ltd.com


LVL

(mA

OD

)

Dep

th

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

Sym

bol

DESCRIPTION

Dep

th

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

Sam

ple

Ref

Sam

ple/

Test

Type

Sym

bol

N-V

alue

Wel

l Dat

a

WS0813-02-07

Window Sampling

C1126

Somic plc


C Wood 0

0

100mm

0.000

-0.300

-0.700

-3.000

Ground SurfaceMADE GROUNDConcrete.MADE GROUNDClinker, brick fragments, gravel and pebbles.CLAYStiff light brown CLAY with occasional gravel.

End of Borehole

WS08 /0.5m

WS08 /1.5m

No installation.


Method:

Project No:

Client:

Site Location:

Engineer: Easting:

Northing:


Sheet: 1 of 1

Comments:

www.celtic-ltd.com


LVL

(mA

OD

)

Dep

th

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

Sym

bol

DESCRIPTION

Dep

th

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

Sam

ple

Ref

Sam

ple/

Test

Type

Sym

bol

N-V

alue

Wel

l Dat

a

WS0913-02-07

Window Sampling

C1126

Somic plc


C Wood 0

0

100mm

0.000-0.200-0.400

Ground SurfaceMADE GROUNDConcrete.MADE GROUNDBrick fragments and gravel.

End of Borehole

WS09 /0.4m

Borehole terminated due to obstruction at 0.4m bgl.


Method:

Project No:

Client:

Site Location:

Engineer: Easting:

Northing:


Sheet: 1 of 1

Comments:

www.celtic-ltd.com


LVL

(mA

OD

)

Dep

th

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

Sym

bol

DESCRIPTION

Dep

th

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

Sam

ple

Ref

Sam

ple/

Test

Type

Sym

bol

N-V

alue

Wel

l Dat

a

WS1114-02-07

Window Sampling

C1126

Somic plc


C Wood 0

0

100mm

0.000-0.200

-0.600

-1.000

-1.600

-3.000

Ground SurfaceMADE GROUNDConcrete.MADE GROUNDGravel, pebbles, brick fragments and clinker.CLAYFirm black CLAY with occasional gravel.CLAYSoft black CLAY with occasional gravel. Organic odour.CLAYStiff light brown CLAY with occasional gravel.

End of Borehole

WS11 /0.5m

WS11 /1.1m

WS11 /2.5m

No installation.


Method:

Project No:

Client:

Site Location:

Engineer: Easting:

Northing:


Sheet: 1 of 1

Comments:

www.celtic-ltd.com


LVL

(mA

OD

)

Dep

th

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

Sym

bol

DESCRIPTION

Dep

th

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

Sam

ple

Ref

Sam

ple/

Test

Type

Sym

bol

N-V

alue

Wel

l Dat

a

WS1214-02-07

Window Sampling

C1126

Somic plc


C Wood 0

0

100mm

0.000

-0.300

-0.700

-1.700

-3.000

Ground SurfaceMADE GROUNDConcrete.MADE GROUNDClinker, brick fragments, and gravel.CLAYSoft black CLAY with occasional gravel.

CLAYVery stiff light brown CLAY with occasional gravel.

End of Borehole

WS12 /0.5m

WS12 /1.0m

WS12 /1.5m

WS12 /2.5m


Method:

Project No:

Client:

Site Location:

Engineer: Easting:

Northing:


Sheet: 1 of 1

Comments:

www.celtic-ltd.com


LVL

(mA

OD

)

Dep

th

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

Sym

bol

DESCRIPTION

Dep

th

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

Sam

ple

Ref

Sam

ple/

Test

Type

Sym

bol

N-V

alue

Wel

l Dat

a

WS1314-02-07

Window Sampling

C1126

Somic plc


C Wood 0

0

100mm

0.000-0.200

-0.700

-3.000

Ground SurfaceMADE GROUNDConcrete.CLAYUncompacted black CLAY with occasional cobble.CLAYStiff light brown CLAY with occasional gravel.

End of Borehole

WS13 /0.5m

WS13 /1.5m

WS13 /2.5m



APPENDICES C



(I) CHEMICAL TEST RESULTS



(II) ENGINEERING TEST RESULTS



APPENDIX D

GROUND GAS RESULTS

Table D-A – Ground Gas Monitoring Result

Methane (% V/V) Oxygen (% V/V) Carbon Dioxide (% V/V) 26/02/07 14/03/07 22/03/07 26/02/07 14/03/07 22/03/07 26/02/07 14/03/07 22/03/07

WS01 <0.1 <0.1 <0.1 6.7 3.2 2.3 2.6 3.0 2.8 WS02 <0.1 <0.1 <0.1 18.1 18.0 17.0 0.1 0.2 0.4 WS05 <0.1 <0.1 <0.1 20.0 20.5 20.4 0.4 0.2 0.2 WS12 <0.1 <0.1 <0.1 16.5 17.1 17.2 3.1 3.7 4.5 WS13 0.3 <0.1 <0.1 14.4 10.1 11.4 6.1 10.9 8.2

Table D-B –Gas Screening (GSV) Values calculated from Maximum Flow Rates (L/hr)

Gas Flow Rate (L/hr) Barometric Pressure (mb) Carbon Dioxide

Gas Screening Value (L/hr)* 14/03/07 26/02/07 14/03/07 22/03/07 22/03/07 26/02/07 14/03/07 22/03/07WS01 6.4 2.6 1004 1026 1009 - 0.19 0.07 WS02 2.7 0.1 1005 1026 1010 - 0.01 0.01 WS05 2.5 0.4 1005 1026 1010 - 0.28 0.01 WS12 2.5 3.1 1005 1026 1010 - 0.09 0.11 WS13 2.6 6.1 1006 1026 1010 - 0.01 0.19

* Derived GSV for each boreholes were calculated using worst case flow rate (indicated in Bold script); for example, GSV values for WS01 (12/03/07) were calculated from 6.4 L/hr x 3.0%

London & South East: 22-42 Livingstone Road Stratford London E15 2LJ t. 0870 850 2974 f. 029 2036 8637 www.celtic-ltd.com Wales & Midlands Columbus House Greenmeadow Springs Tongwynlais Cardiff CF15 7NE t. 029 2036 8636 f. 029 2036 8637 www.celtic-ltd.com North West Centrix House Crow Lane East Newton le Willows St Helens WA12 9UY t. 01925 273 222 f. 029 2036 8637 www.celtic-ltd.com

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