GENERIC QUANTITATIVE RISK ASSESSMENT - Devon · water or soil gas at a site with generic assessment criteria. Generic assessment criteria are typically conservative to ensure that

SECTION 6

GENERIC QUANTITATIVE RISK ASSESSMENT

SECTION 6GENERIC QUANTITATIVE RISK ASSESSMENT

Combined Phase I and Phase II Investigation Prepared by PBHPE98123A for Devon County CouncilJanuary 2009 Page 53

6 GENERIC QUANTITATIVE RISK ASSESSMENT (GQRA)

6.1 Context and Objectives

6.1.1 This section makes use of the site investigation findings, as described in the previoussection, to evaluate further the potential pollutant linkages identified in Section 4. Acombination of qualitative and quantitative techniques is used, as described below.

6.1.2 GQRA involves the comparison of contaminant concentrations measured in soil,water or soil gas at a site with generic assessment criteria. Generic assessmentcriteria are typically conservative to ensure that they are applicable to the majority ofsites and normally apply to only a limited number of pollutant linkages.

6.2 Numerical Assessment Criteria - Soils

6.2.1 Various numerical assessment criteria have been used to interpret the chemicaltesting results, as described in this section. These criteria are generally set to behighly conservative and in the event that they are exceeded a further level of analysisis typically required.

Soils

6.2.2 The assessment criteria used for the screening of determinands within soils areidentified within Table 6.1. Details of input parameters are given within the footers toSummary Tables 6.3 – 6.6.

Table 6.1: Selected Assessment Criteria – Contaminants in Soils

Substance Group Determinand(s) Assessment CriteriaSelected

Organic Substances

Volatile OrganicCompounds (VOCs).

Benzene, Toluene, EthylbenzeneXylenes, Vinyl Chloride, 1,1,1-Trichloroethane, 1,2-Dichloroethane, Trichloroethene,Tetrachloroethene,

1,3,5-Trimethylbenzene,

1,2,4-Trimethylbenzene,Chlorobenzenes.

CLEA UK (beta)

Non-halogenatedhydrocarbons.

Total Petroleum Hydrocarbons(TPHCWG banded)

CLEA UK (beta)



Table 6.1: Selected Assessment Criteria – Contaminants in Soils


Polycyclic AromaticHydrocarbons (PAH’s).

Naphthalene, Acenaphthylene,Acenaphthene, Fluorene,Phenanthrene, Anthracene,Fluoranthene, Pyrene,Benz(a)anthracene, Chrysene,Benz(b)fluoranthene,Benz(k)fluoranthene,Benzo(a)pyrene (BAP),Indeno(1,2,3-cd)pyrene,Dibenz(a,h)anthracene,Benzo(ghi)perylene

CLEA UK (beta)

Inorganic Substances

Lead, SGV ReportsHeavy metals andmetalloids.

Arsenic, Cadmium, Copper, Zinc,Nickel, Selenium, Mercury,Chromium

CLEA UK (beta)

Cyanides. Free Cyanide CLEA UK (beta)

Sulphates Total Sulphate BRE Special Digest1:2005

6.2.3 The Guideline Values have been derived on the basis of a particular land-use.Currently there are only three types of land-use for which Guideline Valueshave been developed: residential, allotments and commercial/industrial.

6.2.4 The standard land-uses take into account human behaviour and the professionaljudgment of policy-makers to provide a conceptual model suitable for a range ofgeneric site conditions and land-uses. They are not intended to reflect accuratelyeither the conditions of a specific site or the behaviour of a specific site-user. Thiswould be covered by more detailed assessment if this is required.

6.2.5 In this case the residential without plant uptake land use has been selected to behighly conservative. If applying these generic assessment criterions with limitingconservative assumptions provides an acceptable answer to the question, then thereis no need to initiate a more detailed site-specific risk assessment.

6.2.6 Whilst it is appreciated that this standard land use is not the same as the current landuse, as common land, it is thought to be the most appropriate generic riskassessment criteria available for the initial screen.

CLEA UK

6.2.7 In November 2005 the EA released CLEA UK (beta version), the updated version ofthe CLEA 2002 model. The CLEA 2002 model and supporting CLR technicalpackage was originally released by the DEFRA in 2002 to provide a scientificallybased framework for assessing chronic risks to human health posed by landcontamination in the United Kingdom.



6.2.8 On 9th October 2006 the EA formally withdrew the CLEA 2002 software, stating itlacked the versatility of CLEA UK (beta version). Furthermore, the EA alsorecommended the use of CLEA UK in human health risk assessments.

6.2.9 In August 2008 announcements were made by DEFRA and the EA indicating that thecurrent SGVs and the CLR7-10 have been withdrawn.

6.2.10 A new CLEA model has been released as have replacement documents for CLR7and 10. PB has reviewed what is currently available and whilst the model will be easyto use - it has a number of key parameters missing - some of which will be releasedwith the awaited new SGV reports and a new physical/chemical database.

6.2.11 Legislation dictates that any model used for assessing the results of contaminatedland investigations has to be scientifically robust and justifiable. The new CLEAmodel requires a number of parameters (particularly for the plant uptake model) whichhave not been published by DEFRA and therefore the model does not satisfy thebasic requirements of this legislation.

6.2.12 Until such time that the appropriate toxicological data, physico-chemical data andexposure data are available, PB will continue to use CLEA UK (which is referred to inCLR11) and the existing data to undertake risk assessment work. The latter will bealtered from the previous default parameters where these are known - for examplebody weight information and the 80% rule have both changed with the latestinformation release form DEFRA. At the moment there is particular ambiguity relatingto new Conversion Factors (CF) for plant uptake of inorganic contaminants and itappears these will be available when the new SGV reports are released. In additionthere will be a new Index Dose for Lead so the current blood level model is to bereplaced.

6.2.13 All model assumptions and input parameters (both toxicological and fate & transport),in addition to full CLEA UK report summaries, are provided within Appendix G.

CLEA UK Input Criteria

6.2.14 The ‘residential without plant uptake’ land use scenario has been selected from thoseavailable within the CLEA UK (beta) model and SGV reports for the development ofconservative generic assessment criteria (GAC).

6.2.15 It is recognised that the standard ‘residential without plant uptake’ land use representsa range of generic site conditions and is not intended to accurately reflect the specificsite conditions or the behaviour of a particular individual at the site. Shouldexceedances of the GAC be identified, site specific refinements to the model can bemade at a later stage in the assessment process.

6.2.16 The input criteria used for the development of GAC within CLEA UK, and whereappropriate, those required for selection of the correct screening criteria from SGVreports, are provided within Tables 6.2.



Table 6.2: CLEA UK Input Criteria – Residential without Plant Uptake

Input Details Value

Land Use Residential without plant uptake

Building Type Typical House

Receptor Female

Age Class 1 – 6

Exposure Duration 6 years

Averaging Time 6 years

Direct Soil IngestionOral

Direct Soil Derived Indoor Dust Ingestion

Skin Contact with Soil Derived Indoor DustDermal

Skin Contact with Soil

Inhalation of Soil Derived Indoor Dust

Inhalation of Soil Dust

Inhalation of Soil Vapours Indoors

Inhalation

Inhalation of Soil Vapours Outdoors

Soil Type Sandy

pH 8

Soil Organic Matter(SOM)

2.5%

6.2.17 A pH value of ‘8’ has been used for the derivation of all generic screening criteria, andis considered to be representative of the prevailing soil conditions across the site.This value has been obtained by converting all pH values to hydrogen ionconcentrations, averaging them, and then using the product to complete the averagepH. Full calculations are provided within Appendix G.

6.2.18 The CLEA UK model only offers the option of selecting a soil organic matter (SOM)value of 1%, 2.5% or 5%. The SOM values were averaged across the site. Theaveraged SOM value was rounded to 2.5%. Full calculations are provided withinAppendix G.

6.3 Soil Analysis Results

6.3.1 Laboratory analysis for soils are summarised in Tables 6.3 - 6.6. Raw laboratory datais included as Appendix F.



Table 6.3: Soil Laboratory Analysis Results – Metals and Metalloids

Determinand UnitNo.

sampletested

Screening Criteria Min Max NoExceed

Arsenic B mg/kg 114 22.3 CLEA UK 4.4 80 18

Cadmium B mg/kg 114 33.1 CLEA UK <0.1 3.7 0

Chromium B mg/kg 114 159 CLEA UK <5 62 0

Lead A mg/kg 114 450 SGV 10 <5 3700 6

Mercury B mg/kg 114 16.7 CLEA UK <0.1 5.6 0

Nickel B mg/kg 114 72.2 CLEA UK 6.2 93 0

Copper B mg/kg 114 2250 CLEA UK <5 450 0

Zinc B mg/kg 114 8420 CLEA UK 16 9300 1

Selenium B mg/kg 114 266 CLEA UK <0.2 2 0

Boron (B) WaterSoluble mg/kg 114 - - <0.4 18 -

Table 6.4: Soil Laboratory Analysis Results – Total Petroleum Hydrocarbons(TPH)

Determinand UnitNo.

sampletested


Aliphatic EC 5-6 B mg/kg 27 4.58 CLEA UK <0.1 <0.1 0



Aliphatic EC 10-12B mg/kg 27 24.4 CLEA UK <0.1 <0.1 0

Aliphatic EC 12-16B mg/kg 27 107 CLEA UK <0.1 <0.1 0

Aliphatic EC 16-35B mg/kg 27 27700 CLEA UK <0.1 2.6 0

Aromatic EC 5-7 B mg/kg 27 1.42 CLEA UK <0.1 51 0

Aromatic EC 7-8 B mg/kg 27 1.63 CLEA UK <0.1 <0.1 0

Aromatic EC 8-10 B mg/kg 27 6.78 CLEA UK <0.1 <0.1 0

Aromatic EC 10-12B mg/kg 27 34.1 CLEA UK <0.1 2.7 0

Aromatic EC 12-16B mg/kg 27 152 CLEA UK <0.1 31 0




Table 6.4: Soil Laboratory Analysis Results – Total Petroleum Hydrocarbons(TPH)

Determinand UnitNo.

sampletested



TPH (C5-C38) mg/kg 27 - - <10 140 -

Table 6.5: Soil Laboratory Analysis Results – Volatile Organic Compounds(VOCs)

Determinand UnitNo.

sampletested


Benzene B mg/kg 27 0.0868 CLEA UK <0.001 0.023 0

Toluene B mg/kg 27 7.81 CLEA UK <0.001 0.016 0

Ethyl BenzeneB mg/kg 27 40.8 CLEA UK <0.001 0.038 0

Xylene B mg/kg 27 19.1 CLEA UK <0.001 0.687 0

Chloro-benzenes(total)B

mg/kg 27 87.1 CLEA UK <0.001 0.0028 0

1,2-DichloroethaneB

mg/kg 27 0.0256 CLEA UK <0.002 <0.002 0

Tetrachloroethene B mg/kg 27 2.59 CLEA UK <0.001 <0.001 0

1,1,1-TrichloroethaneB

mg/kg 27 29.5 CLEA UK <0.001 <0.001 0

Trichloroethene B mg/kg 27 0.346 CLEA UK <0.001 0.850 2

Vinyl ChlorideB mg/kg 27 0.00248 CLEA UK <0.001 0.003 1

Phenol B mg/kg 27 34,500 CLEA UK <0.3 1 0

Thiocyanate B mg/kg 27 170 CLEA UK <5 <5 0



Table 6.6: Soil Laboratory Analysis Results – Polycyclic AromaticHydrocarbons (PAHs)

Determinand UnitNo.

sampletested

Screening Criteria Min Max No.Exceed

Naphthalene B mg/kg 114 17.1 CLEA UK <0.1 1.1 0

Acenaphthylene B mg/kg 114 18.6 CLEA UK <0.1 1.5 0

Acenaphthene B mg/kg 114 39.8 CLEA UK <0.1 5.5 0

Fluorene B mg/kg 114 2740 CLEA UK <0.1 12 0

Phenanthrene B mg/kg 114 263 CLEA UK <0.1 16 0

Anthracene B mg/kg 114 20,500 CLEA UK <0.1 20 0

Fluoranthene B mg/kg 114 1370 CLEA UK <0.1 27 0

Pyrene B mg/kg 114 1370 CLEA UK <0.1 22 0

Benzo(a)anthracene B mg/kg 114 13.7 CLEA UK <0.1 16 1

Chrysene B mg/kg 114 13.7 CLEA UK <0.1 15 2

Benzo(b)fluoranthene B mg/kg 114 13.7 CLEA UK <0.1 15 1

Benzo(k)fluoranthene B mg/kg 114 13.7 CLEA UK <0.1 8.1 0

Benzo(a)pyrene B mg/kg 114 1.34 CLEA UK <0.1 17 34

Indeno(123-cd)pyrene B mg/kg 114 13.7 CLEA UK <0.1 12 0

Dibenz(ah)anthracene B mg/kg 114 1.37 CLEA UK <0.1 3.2 6

Benzo(ghi)perylene B mg/kg 114 13.7 CLEA UK <0.1 11 0

Total PAH mg/kg 114 - - <2 160 -

Notes: A SGV screening criteria selected (for residential without plant uptake end use)B Generic assessment criteria derived using CLEA UK (beta), for residential without plantuptake end use. Input parameters of pH 8 and SOM 2.5% selected. Justifications for alltoxicological data and fate & transport data, entered into CLEA UK for individualcontaminants, are provided within Appendix E.n/a Not applicable

6.3.2 Concentrations of metals and metalloids where detected. A number of these sampleswere found to be above the screening criteria, as described below:

18 out of 114 samples were found to be above the screening criteria for Arsenic(22.3mg/kg). 7 of these samples were taken from the top 1m. The highestconcentration of Arsenic was found in TP12 at 3.2 mBGL at a concentration of80mg/kg.



6 out of 114 samples were found to be elevated above the screening criteria forlead (450mg/kg). Two of these were taken from the top1m. The highestconcentration of Lead found was 3700mg/kg in WS4 at a depth of 0.4 mBGL.

One out of 114 samples of zinc was found to be elevated above the screeningcriteria of 8420mg/kg. This sample was from TP18 at 3 mBGL at a concentrationof 9300mg/kg.

6.3.3 Concentrations of VOCs including Benzene, Toluene, Ethyl Benzene and Xylene,were below the relevant screening thresholds with the exception of Trichloroethene(TCE) and Vinyl Chloride (VC).

One out of 27 samples of vinyl chloride was found to be elevated above thescreening criteria of 2.48ug/kg. This sample was from TP13 at a depth of 2.9mBGL at a concentration of 3ug/kg.

Two out of 27 samples of Trichloroethene were found to be above the screeningcriteria of 346ug/kg. These were found in BH105 and BH106 at concentrations of850 and 420ug/kg respectively. Both samples were taken at a depth of 1 mBGL.

6.3.4 The following VOCs were noted at concentration above detection limit of the analysis;

cis-1,2-Dichloroethene at 3 locations. The maximum concentration was 48ug/kgin BH105 at 1 mBGL;

Trichloroethane at concentration of 45uk/kg in WS3 at 0.4 mBGL ;

Isopropylbenzene at 3 locations. The maximum concentrations was 22ug/kg inBH105 at 1 mBGL;

n-Propylbenzene at 2 locations. The maximum concentration was 28ug/kg inBH105 at 1 mBGL;

1,3,5-Trimethylbenzene at 6 locations. The maximum concentration was 36ug/kgin BH105 at 1 mBGL;

tert-Butylbenzene at concentration of 2.2ug/kg in TP26 at 1.9mBGL;

1,2,4-Trimethylbenzene at 6 locations. The maximum concentration was200ug/kg in BH105 at 1 mBGL;

sec-Butylbenzene at concentration of 1.2ug/kg in TP26 at 1.9mBGL;

4-Isopropyltoluene at 2 locations. The maximum concentration was 63ug/kg inBH105 at 1 mBGL;

6.3.5 Polycyclic Aromatic Hydrocarbons (PAHs) were found to be present within a numberof samples, some of which were above the screening criteria as described below:

Two out of 114 samples were found to be above the screening criteria forChrysene (13.7mg/kg). These were found in TP01 and WS1 at depths of 1.2 and1.5 mBGL respectively, both at a concentration of 15mg/kg.



One out of 114 samples was found to be elevated above the screening criteriafor Benzo(a)anthracene (13.7mg/kg). This sample was from WS1 at a depth of1.5 mBGL at a concentration of 16mg/kg.

34 out of 114 samples were found to be elevated above the screening criteria forBenzo(a)pyrene (BAP) (1.34mg/kg). 6 of these samples were taken from the top1m. The highest concentration of BAP was found in TP01 at a depth of 1.2mBGL at a concentration of 17mg/kg.

6 out of 114 samples were found to be elevated above the screening criteria forDibenzo[a,h]anthracene (1.37mg/kg). Two of these samples were taken withinthe top 1m. The highest concentration of Dibenzo[a,h]anthracene was found inTP01 at a depth of 1.2 mBGL at a concentration of 3.2mg/kg.

6.3.6 Where an integrated screening value was not available the screening value chosenwas either the Oral and Dermal or Inhalation value, whichever was lower.

Asbestos

6.3.7 62 samples were screened for potential asbestos containing material submitted foranalytical identification. None of the samples analysed returned positive results for .

6.4 Assessment Criteria – Water, Leachate and Eluate

6.4.1 A groundwater, leachate and eluate quality assessment has been undertaken inaccordance with the EA P20 Document. This assessment corresponds with a Tier 1assessment (leachate) and Tier 2 analysis (groundwater).

6.4.2 The assessment criteria used for the screening of determinands within leachate,eluate and groundwater are detailed within Table 6.7. Details of input parameters aregiven within the footers to Summary Tables 6.8 – 6.15.

6.4.3

Table 6.7: Selected Assessment Criteria – Contaminants in Leachate, Eluate,Groundwater and Surface Water


Organic Substances

Volatile OrganicCompounds (VOCs)

Benzene, Toluene, Xylenes,Styrene, Tetrachloroethene,Tetrachloromethane,

1,1,1-Trichloroethane,Trichloroethene,

1,2-Dichloroethane,Hexachlorobutadiene

EQS





Ethylbenzene,

1,1-Dichloroethene,

1,2-Dichlorobenzene,

1,4-Dichlorobenzene

WHO Health

Vinyl chloride,

1,2-Dichloropropane

UK DWS

Naphthalene EQSPolycyclic AromaticHydrocarbons (PAH’s)

Acenaphthylene, Fluorene,Phenanthrene, Anthracene,Fluoranthene, Pyrene,Benz(a)anthracene, Chrysene,Benzo(b)fluoranthene,Benzo(k)fluoranthene,Benzo(a)pyrene,Dibenz(a,h)anthracene,Benzo(ghi)perylene

LEC

Total PetroleumHydrocarbons

Aliphatic C5-C6,

Aliphatic >C6-C8,

Aliphatic >C8-C10.

Aliphatic >C10-C12,

Aliphatic >C12-C16,

Aliphatic >C16-C21,

Aromatic C5-C7,

Aromatic >C7-C8,

Aromatic >C8-C10,

Aromatic >C10-C12,

Aromatic >C12-C16,

Aromatic >C16-C21,

Aromatic> C21-C35

Dutch Intervention Values

Inorganic Substances

Heavy metals andmetalloids

Arsenic, Cadmium, Lead, Nickel,Mercury, Chromium, Copper, Zinc,Boron

EQS

Heavy metals andmetalloids

Selenium UK DWS





Cyanides Total Cyanide EQS

Sulphates Total SO42- BRE Special Digest

1:2005

WHO – World Health OrganisationLEC – Lowest Effect ConcentrationBRE – Building Research Establishment

6.4.4 A brief discussion of each source of criteria is provided below.

Environmental Quality Standards (EQS)

6.4.5 EQS have been released by the EA for dangerous substances, as identified by theEuropean Commission (EC) Dangerous Substances Directive. EQS can vary foreach substance, for the hardness of the water and can be different for fresh, estuarineor coastal waters.

6.4.6 As the site is surrounded by coastal waters the EQS values that have been used forthis site are associated with salt water.

Lowest Effect Concentration (LEC)

6.4.7 These criteria relate to the concentration of PAHs in groundwater. They are takenfrom the EA R&D Technical Report P45 – Polycyclic Aromatic Hydrocarbons (PAH):Priorities for Environmental Quality Standard Development (2001).

WHO Health

6.4.8 These screening criteria have been taken from the World Health OrganisationGuidelines for Drinking Water Quality (1984). The health value is a guideline valuerepresenting the concentration of a contaminant that does not result in any significantrisk to the receptor over a lifetime of exposure.

UK Drinking Water Standards (DWS)

6.4.9 Groundwater results have been compared against screening criteria taken from DWSDrinking Water (Water Quality) Regulations 2000.

Dutch Intervention Values

6.4.10 The Dutch Institute and Human Toxicology data are used for speciated TPH. Whilstthey do not have force of law in the UK, they are recognised as a valid source ofinformation by the EA. For example, they are recommended in the EA document‘Biological Test Methods for Assessing Contaminated Land’.



6.5 Groundwater Analysis Results

6.5.1 Laboratory analysis for groundwater are summarised in Tables 6.8-6.12. Rawlaboratory data is included as Appendix F.

Table 6.8: Groundwater Laboratory Analysis Results – Metals and Metalloids

Determinand UnitNo.

sampletested

ScreeningCriteria Min Max No.

Exceed

BOD mg O2 l-¹ 34 N/A <3 350.0 -

COD mg O2 l-¹ 34 N/A 28 920.0 -

Cyanide (total) mg l-¹ 34 N/A < 0.05 < 0.05 -

Cyanide (free) mg l-¹ 20 N/A < 0.05 < 0.05 -

Thiocyanate mg l-¹ 20 N/A < 0.5 < 0.5 -

AmmoniacalNitrogen asFree Ammonia

mg l-¹ 34 0.021 DWS < 0.02 3.8 26

Chloride mg l-¹ 26 25 DWS 139.6 21000.0 18

SO42- mg l-¹ 34 25 DWS < 1.0 2600.0 24

Hardness mgCaCO3 l-¹

26 N/A 110 5000.0 -

Sulphide mg l-¹ 20 N/A < 0.05 < 0.05 -

Phenol mg l-1 21 0.03 EQS <0.03 0.1 2

Table 6.8: Groundwater Laboratory Analysis Results – Metals and Metalloids

Determinand UnitNo.

sampletested

ScreeningCriteria Min Max No. Exceed

Arsenic ug/l 34 25 EQS 2.6 1800 15

Cadmium ug/l 34 2.5 EQS <0.5 0.62 0

Chromium ug/l 34 15 EQS 4.1 157 30

Lead ug/l 34 25 EQS <1 4.5 0

Mercury ug/l 34 0.3 EQS <0.5 2.5 11

Nickel ug/l 34 30 EQS <1 29 0

Copper ug/l 34 5 EQS 2 397 0

Zinc ug/l 34 N/A N/A 1.8 72 0

Selenium ug/l 34 10 WHO <1 72 15

Boron ug/l 34 7000 EQS 306 5370 0



Table 6.9: Groundwater Laboratory Analysis Results – Pesticides

Determinand UnitNo.

sampletested


Azinphos methyl ug/l 20 0.01 EQS <0.2 <0.2 -

Coumaphos ug/l 20 0.04 EQS <0.2 <0.2 -

Demeton (O+S) ug/l 20 0.5 EQS <0.2 <0.2 -

Atrazine ug/l 20 2 EQS <0.2 <0.2 0

Simazine ug/l 20 2 EQS <0.2 <0.2 0

Aldrin ug/l 20 0.01 EQS <0.2 <0.2 -

Heptachlor ug/l 20 0.03 WHO <0.2 <0.2 -

Endosulfan I ug/l 20 0.003 EQS <0.2 <0.2 -

Dieldrin ug/l 20 0.01 EQS <0.2 <0.2 -

Endrin ug/l 20 0.005 EQS <0.2 <0.2 -

Table 6.10: Groundwater Laboratory Analysis Results – VOCs

Determinand UnitNo.

SamplesTested


Exceeded

Benzene B ug/l 22 30 EQS <1 7.1 0

Toluene B ug/l 22 50 EQS <1 4.4 0

Ethyl Benzene B ug/l 22 300 EQS <1 30 0

Xylene B ug/l 22 30 EQS <1 16.2 0

1,2-Dichloroethane ug/l 22 10 EQS <2 11 1

1,1-Dichloroethene ug/l 22 30 WHO <1 <1 0

1,2-Dibromo-3-chloropropane ug/l 21 1 WHO <50 <50 -

1,2-Dichlorobenzene ug/l 21 1000 WHO <1 <1 0

1,2-Dichloropropane ug/l 22 20 WHO <1 <1 0

1,3-Dichloropropane ug/l 22 20 WHO <10 <10 0

1,4-Dichlorobenzene ug/l 22 300 WHO <1 2.1 0

Dichloromethane ug/l 22 20 WHO <10 <10 0



Table 6.10: Groundwater Laboratory Analysis Results – VOCs

Determinand UnitNo.

SamplesTested


Exceeded

Hexachloro-butadiene ug/l 21 0.1 EQS <1 <1 -

Styrene ug/l 22 50 EQS <1 <1 0

Tetrachloroethene ug/l 22 10 EQS <1 <1 0

Tetrachloro-methane ug/l 22 12 EQS <1 <1 0

1,1,1-Trichloroethane ug/l 22 100 EQS <1 <1 0

1,1,2-Trichloroethane ug/l 22 300 EQS <10 <10 0

Trichloroethene ug/l 22 10 EQS <1 <1 0

Vinyl chloride ug/l 22 5 WHO <1 <1 0

Table 6.11: Groundwater Laboratory Analysis Results – PetroleumHydrocarbons

Determinand UnitNo.

sampletested


Aliphatic EC 5-6 C ug/l 22 - - <0.1 <0.1 -

Aliphatic EC 6-8 C ug/l 22 444 DIV <0.1 <0.1 0


Aliphatic EC 10-12C ug/l 22 10 DIV <0.1 <0.1 0

Aliphatic EC 12-16C ug/l 22 0.59 DIV <0.1 <0.1 0


Aliphatic EC 21-35C ug/l 22 - - <0.1 <0.1 -

Aromatic EC 6-7 C ug/l 22 - - <0.1 31.0 -

Aromatic EC 7-8 C ug/l 22 - - <0.1 7.7 -

Aromatic EC 8-10 C ug/l 22 640 DIV <0.1 68.0 0

Aromatic EC 10-12C ug/l 22 1,331 DIV <0.1 210.0 0

Aromatic EC 12-16C ug/l 22 1,331 DIV <0.1 37.0 0

Aromatic EC 16-21C ug/l 22 543 DIV <0.1 31.0 0



Table 6.11: Groundwater Laboratory Analysis Results – PetroleumHydrocarbons

Determinand UnitNo.

sampletested


Aromatic EC 21-35 C ug/l 22 7 DIV <0.1 <0.1 0

TPH (C5-C38) ug/l 22 10 DWS <10 340.0 4

Table 6.12: Groundwater Laboratory Analysis Results - Polycyclic AromaticHydrocarbons (PAHs)

Determinand UnitNo.

sampletested


Naphthalene ug/l 21 10 EQS <0.1 <0.1 0

Acenaphthylene B ug/l 21 580 LEC <0.1 <0.1 0

Acenaphthene B ug/l 21 - - <0.1 <0.1 -

Fluorene B ug/l 21 210 LEC <0.1 <0.1 0

Phenanthrene B ug/l 21 300 LEC <0.1 <0.1 0

Anthracene B ug/l 21 1.2 LEC <0.1 <0.1 0

Fluoranthene B ug/l 21 0.9 LEC <0.1 <0.1 0

Pyrene B ug/l 21 4 LEC <0.1 <0.1 0

Benzo(a)anthracene B ug/l 21 1.8 LEC <0.1 <0.1 0

Chrysene B ug/l 21 0.7 LEC <0.1 <0.1 0

Benzo(b)fluoranthene B ug/l 21 1.4 LEC <0.1 <0.1 0

Benzo(k)fluoranthene B ug/l 21 1.4 LEC <0.1 <0.1 0

Benzo(a)pyrene B ug/l 21 1.5 LEC <0.1 <0.1 0

Indeno(123-cd)pyrene ug/l 21 - - <0.1 <0.1 -

Dibenz(ah)anthracene B ug/l 21 0.4 LEC <0.1 <0.1 0

Benzo(ghi)perylene B ug/l 21 2 LEC <0.1 <0.1 0

Total PAH ug/l 21 - - <2 5.4 -

Notes: A EQS selected for saltwater



B Screening criteria taken from EA R&D Report P45 “Polycyclic Aromatic Hydrocarbons(PAH): Priorities for Environmental Quality Standard Development” 2001. LEC (lowesteffect concentration) values have been used as screening criteria.C Value for ‘dissolved and emulsified hydrocarbons’

6.5.2 Concentrations of metals and metalloids where detected. A number of these sampleswere found to be above the screening criteria, as described below:

15 samples were found to be above the screening criteria for Arsenic. 1 of thesesamples was taken from boreholes drilled outside the waste mass. 3 of thesesamples were from the borehole installed in the aquifer directly below the waste.11 were from boreholes installed in the waste. The highest concentration ofArsenic was found in the waste at BH108 installed in the waste.

30 samples were found to be above the screening criteria for Chromium. 5 ofthese samples were taken from boreholes drilled outside the waste mass. 4 ofthese samples were from the borehole installed in the aquifer directly below thewaste. 18 were from boreholes installed in the waste and 3 were from boreholespreviously installed by DCC. The highest concentration of Chromium was foundin BH104.

11 samples were found to be above the screening criteria for Mercury. 5 of thesesamples were taken from boreholes drilled outside the waste mass. None ofthese samples were from the borehole installed in the aquifer directly below thewaste. 5 were from boreholes installed in the waste and 1 was from a boreholepreviously installed by DCC. The highest concentration of Mercury was found inBH2. This borehole was installed by DCC. Whilst it is believed to be outside ofthe waste mass no borehole logs are available.

15 samples were found to be above the screening criteria for Selenium. 3 ofthese samples were taken from boreholes drilled outside the waste mass. Noneof these samples were from the borehole installed in the aquifer directly belowthe waste. 9 were from boreholes installed in the waste and 3 were fromboreholes previously installed by DCC. The highest concentration of Seleniumwas found in BH108 installed in the waste.

26 samples were found to be above the screening criteria for mmoniacalnitrogen. 3 of these samples were taken from boreholes drilled outside the wastemass. 4 of these samples were from the borehole installed in the aquifer directlybelow the waste. 15 were from boreholes installed in the waste and 4 were froma borehole previously installed by DCC. The highest concentrations ofammoniacal nitrogen were found in BH106, 108 and 107.

30 samples were found to be above the screening criteria for sulphate-. 7 of thesesamples were taken from boreholes drilled outside the waste mass. 1 of thesesamples were from the borehole installed in the aquifer directly below the waste.11 were from boreholes installed in the waste and 4 were from boreholespreviously installed by DCC. The highest concentration of sulphate- was found inBH104.

30 samples were found to be above the screening criteria for chloride. 5 of thesesamples were taken from boreholes drilled outside the waste mass. 3 of thesesamples were from the borehole installed in the aquifer directly below the waste.4 were from boreholes installed in the waste and 6 were from boreholes



previously installed by DCC. The highest concentration of chloride was found inBH104

2 samples were found to be above the screening criteria for phenol. All theelevated samples came from borehole 109 installed in the waste.

6.5.3 The following Petroleum Hydrocarbons were found to be above the screening criteria:

4 samples were found to be above the screening criteria for total TPH. All theelevated samples came from borehole 109 installed in the waste. TPH bandingof these samples suggested the majority of the total was made up ofhydrocarbons in the late petroleum and diesel range.

6.5.4 Concentrations of VOCs including Benzene, Toluene, Ethyl Benzene and Xylene,were below the relevant screening thresholds with the exception of 1,2Dichloroethane in BH109 during a single monitoring round.

6.5.5 Other VOCs present at concentrations above the detection limit but without screeningcriteria include;

1,1 Dichloroethene

1’1 Dichloropropene

Isopropylbenzene

N-propylbenzene

1,3,5 trimethylbenzene

1,2,4 trimethylbenzene

4 Isopropyltoluene

6.5.6 PAHs were not found at concentrations above the relevant screening criteria.

6.5.7 Pesticides were not found at concentrations above the limit of detection for theanalysis undertaken.

6.6 Eluate Analysis Results

6.6.1 Selected soil samples were scheduled for leachability testing. Laboratory analysiseluates are summarised in Tables 6.13-6.15. Raw laboratory data is included asAppendix F.



Table 6.13: Eluate Laboratory Analysis Results – Metals and Metalloids

Determinand UnitNo.

sampletested


Exceed

Arsenic ug/l 25 25 EQS <1 21.3 0

Cadmium ug/l 25 2.5 EQS <0.5 <0.5 0

Chromium ug/l 25 15 EQS <1 11.2 0

Lead ug/l 25 25 EQS <1 224 1

Mercury ug/l 25 0.3 EQS <0.5 <0.5 0

Nickel ug/l 25 30 EQS <1 10.7 0

Copper ug/l 25 5 EQS <1 12.4 9

Zinc ug/l 25 - - <1 159 -

Selenium ug/l 25 10 WHO <1 <1 0

Boron Ug/l 25 7000 EQS <20 241 0

Table 6.14: Eluate Laboratory Analysis Results – Petroleum Hydrocarbons

Determinand UnitNo.

sampletested


Exceed



Aliphatic EC 10-12C ug/l 25 10 DIV <0.1 <0.1 0


Aliphatic EC 16-21C ug/l 25 0.001 DIV <0.1 <0.1 -

Aliphatic EC 21-35C ug/l 25 - - <0.1 <0.1 -


Aromatic EC 10-12C ug/l 25 1,331 DIV <0.1 <0.1 0

Aromatic EC 12-16C ug/l 25 1,331 DIV <0.1 <0.1 0

Aromatic EC 16-21C ug/l 25 543 DIV <0.1 <0.1 0


TPH (C5-C38) ug/l 25 10 DWS <10 <10 0



Table 6.15: Eluate Laboratory Analysis Results – Polycyclic AromaticHydrocarbons (PAHs)

Determinand UnitNo.

sampletested


Exceed

Naphthalene A ug/l 1 10 EQS <0.1 <0.1 0

Acenaphthylene B ug/l 1 580 LEC <0.1 <0.1 0

Acenaphthene B ug/l 1 - - <0.1 <0.1 -

Fluorene B ug/l 1 210 LEC <0.1 <0.1 0

Phenanthrene B ug/l 1 300 LEC <0.1 <0.1 0

Anthracene B ug/l 1 1.2 LEC <0.1 <0.1 0

Fluoranthene B ug/l 1 0.9 LEC <0.1 <0.1 0

Pyrene B ug/l 1 4 LEC <0.1 <0.1 0

Benz(a) anthracene B ug/l 1 1.8 LEC <0.1 <0.1 0

Chrysene B ug/l 1 0.7 LEC <0.1 <0.1 0

Benzo(b)fluoranthene B ug/l 1 1.4 LEC <0.1 <0.1 0

Benzo(k)fluoranthene B ug/l 1 1.4 LEC <0.1 <0.1 0

Benzo(a) pyrene B ug/l 1 1.5 LEC <0.1 <0.1 0

Indeno(123-cd)pyrene B ug/l 1 - - <0.1 <0.1 -

Dibenz(ah)anthracene B ug/l 1 0.4 LEC <0.1 <0.1 0

Benzo(ghi) perylene B ug/l 1 2 LEC <0.1 <0.1 0

Total PAH ug/l 1 - - <2 <2 -

Notes: A EQS selected for saltwaterB Screening criteria taken from EA R&D Report P45 “Polycyclic Aromatic Hydrocarbons(PAH): Priorities for Environmental Quality Standard Development” 2001. LEC (lowesteffect concentration) values have been used as screening criteria.

6.6.2 Leachable metals were generally found to be present but below the screening values,with the exception of Lead and Copper, as described below:

1 eluate sample for Lead was found to be above the screening criteria at aconcentration of 224ug/l in BH106 at 1 mBGL;

9 eluate samples for Copper were found to be elevated above the screeningcriteria. The maximum concentration of Copper was found in TP08 and a depthof 2.1 mBGL.

6.6.3 All samples analysed for PAH and TPH in eluate were found to be below thedetection limit of the analysis.



6.7 Soil Gas and Vapour

6.7.1 Vapour in soil samples

6.7.2 Soil samples taken from across the site which displayed evidence of visual and/orolfactory evidence of contamination were subjected to an initial on site screening witha PID for the presence of volatile organic compounds, as per the criteria outlinedwithin Section 2.8. Results are included within Appendix E.

6.7.3 Average and peak readings were generally below 10 ppm. Risks to future site usersfrom the inhalation of organic vapours are therefore considered to be minimal.

Soil gas from boreholes

6.7.4 Soil gas measurements were taken from all deep boreholes installed across the site.A total of 6 No. monitoring rounds were undertaken under conditions includingreducing, constant and increasing barometric pressure. Fluctuating water tableconditions were also experienced during the monitoring, possibly due to high rainfallover the monitoring period and tidal influences. Concentrations of methane, carbondioxide, oxygen and volatile organic compounds were recorded during each round. Asummary of the results are provided in Table 6.16 and the full monitoring results areincluded within Appendix E.



Table 6.16: Results of Ground Gas Monitoring

O2 (%) CO2 (%) CH4 (%) PIDLocation

R1 R2 R3 R4 R5 R6 R1 R2 R3 R4 R5 R6 R1 R2 R3 R4 R5 R6 R1 R2 R3 R4 R5 R6

BH101 Well Not Installed

BH102 20.0 20.7 20.4 20.4 18.9 20.6 0.2 0.2 00.0 00.0 02.0 00.0 0.2 0.2 0.00 00.0 00.0 00.0 0.1 0.0 0.0 0.0 0.0 0.0

BH103 18.5 18.3 00.3 18.6 20.6 18.1 0.2 0.1 22.5 01.9 00.0 01.9 0.1 0.1 35.7 00.0 00.0 00.0 1.2 0.1 0.0 0.0 0.0 0.0

BH104 0.7 12.4 00.1 00.9 00.1 3.4 20.1 20.1 20.8 22.1 15.2 18.6 33.7 30.0 25.6 24.9 39.6 22.2 0.3 0.5 0.0 0.1 0.0 0.0

BH105 16.0 20.7 20.0 20.1 00.5 20.7 4.1 2.7 00.4 00.1 23.5 00.0 4.1 0.2 00.3 00.0 29.9 00.1 1.1 1.2 0.0 0.0 0.0 14.8

BH106 20.2 20.1 00.3 00.3 06.5 01.3 0.1 0.2 34.1 26.2 13.3 15.7 0.3 0.2 35.5 42.6 26.5 45.3 - 0.0 0.4 0.0 0.0 0.0

BH107 20.6 20.7 20.5 19.9 00.2 20.4 0.0 0.2 00.0 00.3 16.7 00.2 0.2 0.2 00.0 00.2 42.7 00.0 0.6 0.0 0.0 0.0 0.0 0.0

BH108 0.6 4.4 18.6 00.2 20.3 00.1 22.9 22.9 01.7 22.7 00.2 14.9 47.2 42.0 00.0 35.2 00.0 39.4 0.7 0.6 0.0 0.1 0.0 0.0

BH109 1.2 0.7 00.4 00.3 00.7 00.2 35.1 33.0 25.2 33.3 35.0 33.3 82.2 64.2 40.9 56.3 55.7 54.0 - 1.5 0.0 16.9 19.7 13.9

BH110 0.3 1.3 00.3 00.2 00.2 00.1 34.8 28.0 33.1 33.0 34.2 33.7 82.7 82.5 57.3 56.6 56.6 54.0 - 0.9 0.0 8.0 3.1 18.2

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GENERIC QUANTITATIVE RISK ASSESSMENT - Devon · water or soil gas at a site with generic assessment criteria. Generic assessment criteria are typically conservative to ensure that