Contaminated Land Remediation Strategy FINAL · Faber Maunsell Contaminated Land Remediation...

32
Contaminated Land Remediation Strategy: Rugby Cattle Market Final Barteak Developments Limited August 2008

Transcript of Contaminated Land Remediation Strategy FINAL · Faber Maunsell Contaminated Land Remediation...

Page 1: Contaminated Land Remediation Strategy FINAL · Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 3 1.1 Background Faber Maunsell Limited is commissioned

Contaminated Land Remediation Strategy: Rugby Cattle Market

Final

Barteak Developments Limited

August 2008

Page 2: Contaminated Land Remediation Strategy FINAL · Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 3 1.1 Background Faber Maunsell Limited is commissioned

Prepared by: ................................................ Approved by: ................................................. Philip Smart Chris Paterson Technical Director Director Contaminated Land Remediation Strategy: Rugby Cattle Market

Rev No Comments Date

0 Draft to Barteak Developments for comments 1 February 2008

1 FINAL 5 August 2008 14 Queen Victoria Road, Coventry, CV1 3PJ Telephone: 02476 253300 Fax: 02476 253301 Website: http://www.fabermaunsell.com Job No 54735icvg Reference FINAL Date Created August 2008 This contains confidential and commercially sensitive information, which shall not be disclosed to third parties. f:\projects\54735icvg rugby cattle market\report\contaminated land remediation strategy final.doc

Page 3: Contaminated Land Remediation Strategy FINAL · Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 3 1.1 Background Faber Maunsell Limited is commissioned

1 Introduction ..................................................................................................................... 3 1.1 Background........................................................................................................... 3 1.2 Purpose of Report................................................................................................. 3 1.3 Supporting Information ......................................................................................... 3 1.4 Limitations............................................................................................................. 3

2 Site Location and Background Information ................................................................. 6 2.1 Site Location ......................................................................................................... 6 2.2 Site History and Development Proposals ............................................................. 6 2.3 Geology................................................................................................................. 6 2.4 Hydrogeology........................................................................................................ 7 2.5 Hydrology.............................................................................................................. 7 2.6 Previous Investigations......................................................................................... 7 2.6.1 Geology................................................................................................................. 7 2.6.2 Soil quality............................................................................................................. 7 2.6.3 Ground gases ....................................................................................................... 8 2.7 Ground Investigation 2007.................................................................................... 8 2.8 Site Condition Survey ........................................................................................... 9

3 Ground and Groundwater Conditions ........................................................................ 11 3.1 Geology............................................................................................................... 11 3.2 Soil Chemical Results ......................................................................................... 11 3.3 Hydrogeology...................................................................................................... 14 3.3.1 Groundwater level............................................................................................... 14 3.3.2 Groundwater quality............................................................................................ 14 3.4 Ground gases ..................................................................................................... 14 3.5 Summary............................................................................................................. 15

4 Conceptual Model and Risk Assessment................................................................... 17 4.1 Introduction ......................................................................................................... 17 4.2 Conceptual Model ............................................................................................... 17 4.2.1 Sources............................................................................................................... 17 4.2.2 Receptors............................................................................................................ 17 4.2.3 Pathways ............................................................................................................ 17 4.3 Remediation Strategy ......................................................................................... 18 4.3.1 Methodology ....................................................................................................... 18 4.3.2 Remediation Strategy ......................................................................................... 19 4.4 Soils Testing ....................................................................................................... 19 4.5 Compliance with Legislation ............................................................................... 20 4.6 Ground gases ..................................................................................................... 20 4.7 Soakaways.......................................................................................................... 20

5. Conclusions and Recommendations.......................................................................... 23 5.1 Conclusions. ....................................................................................................... 23 5.2 Recommendations .............................................................................................. 24

Table of Contents

Page 4: Contaminated Land Remediation Strategy FINAL · Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 3 1.1 Background Faber Maunsell Limited is commissioned

Figures

Figure 2.1 Plan showing the site location Figure 2.2 Site layout Figure 2.3 Plan of 2006 investigation borehole locations Figure 2.4 Summary of ground contamination identified in 2006 Figure 2.5 Plan of 2007 investigation borehole locations Figure 3.1 Thickness of made ground (m) Figure 3.2 Thickness of sands and gravels (m) Figure 3.3 Depth to Lias Clay (m) Figure 3.4 Geological cross-section Figure 3.5 Groundwater contours (mAOD)

Appendices

Appendix A Site Masterplan 2007 (SK16.11.07A) Appendix B Trial pit, probehole and borehole logs 2007 Appendix C Laboratory data sheets for soil samples 2007 Appendix D Laboratory data sheets for groundwater samples 2007 Appendix E Groundwater level and ground gas monitoring results

Page 5: Contaminated Land Remediation Strategy FINAL · Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 3 1.1 Background Faber Maunsell Limited is commissioned

Introduction

Page 6: Contaminated Land Remediation Strategy FINAL · Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 3 1.1 Background Faber Maunsell Limited is commissioned

Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 3

1.1 Background

Faber Maunsell Limited is commissioned by Barteak Developments Limited to provide technical

advice in respect of the proposed re-development of Rugby Cattle Market for a mixed use

development, including residential and commercial uses. Previous investigations carried out on

the site have shown the presence of ground contamination, with a number of contaminants

present at concentrations above the guidance levels for a residential end use.

1.2 Purpose of Report

The purpose of this report is:-

• to review the ground and groundwater conditions at the Rugby Cattle Market site;

• to identify the potential risks posed by the ground and groundwater conditions at the

site on human health and controlled waters; and

• to identify any remedial measures, which are considered necessary to render the site

suitable for the proposed re-development.

1.3 Supporting Information

The assessment of the ground and groundwater conditions on the site is based on the following

sources of information:-

• British Geological Survey (BGS) 1:50,000 scale map, Sheet 184 Warwick and 1:10,000

scale map SP57NW;

• Faber Maunsell report reference 45773ibme, entitled ‘Rugby Cattle Market:

Contaminated Land Survey Report’ dated March 2006;

• Faber Maunsell report reference 53581cvg, entitled ‘Rugby Cattle Market – Health and

Safety Site Inspection Report and Risk Assessment’ dated September 2007;

• NHBC Document Report No.4, entitled ‘Guidance on evaluation of development

proposals on sites where methane and carbon dioxide are present’ dated March 2007;

• Discussions held with the Contaminated Land Officer of Rugby Borough Council; and,

• The results of a geo-environmental investigation and subsequent environmental

monitoring carried out at the site between November 2007 and January 2008.

1.4 Limitations

This report has been prepared on behalf of and for the sole use of Barteak Developments

Limited. Any third party relies on this report at its own risk unless it is the beneficiary of a

warranty executed by Faber Maunsell Limited specifically for the purpose of creating a duty to

it.

The interpretation of the geological and hydrogeological conditions at the site is based on an

assessment of published information and an extrapolation of point-source information using

geological experience. There is a degree of subjectivity in any interpretation. Groundwater

conditions are subject to variation, the range of which may not have been recorded within the

limited period of monitoring.

1 Introduction

Page 7: Contaminated Land Remediation Strategy FINAL · Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 3 1.1 Background Faber Maunsell Limited is commissioned

Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 4

The design of the ground investigation carried out in November/December 2007 and the

assessment are based on the assumption that the site of the will be developed generally in

accordance with the Masterplan drawing, drawing reference SK16.11.07A provided by Barteak

Developments Limited, reproduced in Appendix A. Should the site be developed for an

alternative use, it may be necessary to re-assess the results and conclusions of this strategy.

The effects of ground and water borne contamination on the environment are constantly under

review and authoritative guidance values are subject to change. The discussions and

conclusions presented in the report are based on the guidance available at the time this report

was prepared. No liability can be accepted for the retrospective effects of any changes or

amendments to the legislation or guidance.

The copyright in this document (including its electronic form) shall remain vested in Faber

Maunsell Ltd but the Client shall have a licence to copy and use the document for the purpose

for which it was provided. Faber Maunsell shall not be liable for the use by any person of the

document for any purpose other than that for which the same were provided by Faber Maunsell.

This document shall not be reproduced in whole or in part or relied upon by third parties for any

use whatsoever without the express written authority of Faber Maunsell.

Page 8: Contaminated Land Remediation Strategy FINAL · Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 3 1.1 Background Faber Maunsell Limited is commissioned

Site Location and Background Information

Page 9: Contaminated Land Remediation Strategy FINAL · Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 3 1.1 Background Faber Maunsell Limited is commissioned

Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 6

2.1 Site Location

The Rugby Cattle Market site is centred on National Grid Reference (NGR) SP509757,

immediately south west of Rugby railway station, as shown on Figure 2.1.

The site consists of a roughly square area of land of approximately 4ha, which is owned by

Rugby Borough Council, together with an additional area to the north of approximately 1.2ha in

private ownership. The Council’s site is occupied largely by the existing cattle market with its

animal stalls, sheds and ancillary buildings in the centre of the site and two public car parks and

a small play area in the southern part of the site. The northern part of the development site is

occupied by the railway station car park in the north eastern corner and by Boults factory in the

north western part of the site.

The proposed development site is bounded to the north by Rugby railway station; to the west by

Railway Terrace; to the east by Murray Road; and to the south by Craven Road. The site

layout is shown on Figure 2.2.

2.2 Site History and Development Proposals

To investigate the previous activities on the site and the potential for past contaminative uses,

historical Ordnance Survey plans of the site and the surrounding area were reviewed for the

period 1889 to 1999. Details of the review and copies of the plans are provided in Faber

Maunsell report of March 2006.

It is understood that the site has been used as a livestock market since 1878. The south

eastern part of the site, now a car park, was used for animal slaughtering and meat processing

from before 1925 until at least 1960. The area of land in the north west of the site, now

occupied by Boults was used as the Tattersalls from at least 1905 until at least 1939. The plan

dated 1960 shows that this area is now occupied by a ‘depot’. The market is currently only in

use on Mondays of each week.

It is proposed that the area of the cattle market, Boults land to the north west and part of the

railway station car park are re-developed for a mixture of residential, commercial and

community uses. The proposed Masterplan for the site is provided at Appendix A. The

Masterplan shows residential development in the eastern half of the site with an hotel at the

northern end. The western half of the site will be re-developed with an area of employment in

the north west, public open space and a community centre in the central part and a nursing

home in the south western corner.

2.3 Geology

The geology of the site is taken from the BGS plans of the area and from the findings of the

ground investigations carried out at the site in January 2006 and in November/December 2007.

On the BGS 1:50,000 scale map, the site is shown as being underlain by the Jurassic, Lower

Lias Clay, consisting of a grey calcareous mudstone, with occasional cementstone bands. In

the south eastern corner, the Lower Lias is covered by the Wolston Clay, a stoneless clay and

silt. The results of the investigations in 2006 and 2007 confirm the presence of the Lower Lias

Clay but suggest that the clay is overlain by a variety of superficial deposits. Much of the cattle

market area has a surface covering of concrete and the car park areas have a covering of

asphalt gravel.

2 Site Location and Background

Information

Page 10: Contaminated Land Remediation Strategy FINAL · Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 3 1.1 Background Faber Maunsell Limited is commissioned

Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 7

2.4 Hydrogeology

It is likely that the clays and mudstone of the Lower Lias have a low primary permeability which

restricts the movement of groundwater. The cementstone bands also have a low primary

permeability but a higher secondary permeability imparted by the presence of fractures, which

facilitate groundwater movement. It is likely that the cementstone bands provide minor but

preferential groundwater flowpaths.

It is likely that the Wolston Clay has a low permeability which restricts vertical groundwater flow

and may support a minor perched water table in the overlying made ground.

The Lower Lias is designated as a non-aquifer in the Environment Agency ‘Groundwater

protection: policy and practice’’. The superficial deposits are classified as a minor aquifer.

There are no licensed groundwater sources within 1km of the site. Based on information

contained in the Rugby Borough Council Contaminated Land Strategy (June 2001), it is

understood that any private water supplies are located in rural areas of the borough and not

within Rugby town.

2.5 Hydrology

The cattle market site is located in the catchment of the River Avon, which flows westerly

approximately 700m to the north of the site (Figure 2.1). There are two licensed water

abstractions from the River Avon, approximately 800m and 900m north of the site. There are

no surface watercourses within 600m of the site.

2.6 Previous Investigations

A ground investigation was carried out at the site by Faber Maunsell Limited, on behalf of

Rugby Borough Council, in January 2006. The investigation was designed to identify the

presence of contaminated ground on the site, which could present a risk to human health and a

constraint on the site development. The investigation was restricted to that part of the site

owned by Rugby Borough Council.

The investigation comprised the drilling of 20 shallow probeholes to a maximum depth of 2m.

The locations of the probeholes are shown on Figure 2.3. Samples of the materials proved in

the probeholes were submitted for geochemical testing and a programme of groundwater and

ground gas monitoring was carried out in 10 probeholes which were equipped for monitoring.

2.6.1 Geology

The probeholes proved a surface layer of made ground/fill, which varied in thickness from

0.15m to 1.2m. The made ground comprised concrete hardstanding, angular sands and

gravels, bricks and general debris.

All of the probeholes proved a light grey clay and a brown sandy, silty clay with sand pockets

below the made ground across the whole site, in contrast to the BGS plan. The full thickness of

the superficial deposits was not proved due to the limited depth of the probeholes.

2.6.2 Soil quality

A total of 30 soil samples of the made ground and underlying natural deposits were analysed

for the presence of contamination. There was evidence of significant organic contamination

and locally elevated metals concentrations in the made ground. There was no evidence of

widespread significant contamination in the underlying superficial deposits. Elevated metal

concentrations were reported principally for arsenic, up to 56mg/kg; boron, up to 8.7mg/kg;

copper, up to 690mg/kg; lead, up to 1800mg/kg; nickel, up to 110mg/kg; and, zinc up to

850mg/kg.

The contamination in the made ground was associated principally with polycyclic aromatic

hydrocarbons (PAH), including benzo(a)pyrene (BaP). Total petroleum hydrocarbons were

recorded up to 17,000mg/kg and PAH(16) up to 1542mg/kg. BAP was recorded up to

120mg/kg. The organic contamination was attributed to the tarmac asphaltic gravel which has

been used as a surface covering to the car parks and which also is present in the sub-base

materials. Locally elevated concentrations of arsenic, nickel, lead and boron were present in

the made ground (Figure 2.4).

Page 11: Contaminated Land Remediation Strategy FINAL · Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 3 1.1 Background Faber Maunsell Limited is commissioned

Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 8

Apart from one sample in probehole WS6, on the southern edge of the site, contamination of

the natural deposits was limited to locally elevated concentrations of arsenic and boron, which

are present at much lower concentrations than in the made ground. From discussions with the

Contaminated Land Officer of Rugby Borough Council, it is understood that elevated arsenic

concentrations are present naturally in soils in the area and reflect the weathering of

argillaceous materials such as silt and clay.

Based on the findings of the soils analyses in 2006, it was concluded that the recorded levels of

soil contamination in the surface layer of made ground posed a risk to human health and, in the

absence of remedial measures, placed a constraint on any proposed development of the site.

2.6.3 Ground gases

The 10 monitoring probeholes were monitored for the presence of ground gases (methane,

carbon dioxide, oxygen, hydrogen sulphide and carbon monoxide) together with the gas flow

rate on three occasions in January 2006. Methane was recorded in two probeholes at

concentrations up to 2.4%v/v. Carbon dioxide was recorded in all the probeholes, with the

maximum recorded concentration of 10.2%v/v. Carbon dioxide above the guidance level of

5%v/v was reported in five of the probeholes. Elevated gas flow rates were not recorded in any

of the probeholes with a maximum flow of 0.7 l/hour.

2.6.4 Groundwater quality

Due to the limited depth of the probeholes, it only was possible to recover groundwater samples

from five of the probeholes. The remaining five probeholes were dry.

The laboratory analyses of the samples showed generally minor contamination of the

groundwater principally with hydrocarbons and locally ammoniacal nitrogen. The recorded

hydrocarbon levels generally were low at less than 0.3ng/l, apart from the sample from

probehole WS20 on the central part of eastern site boundary, which recorded TPH (C5-C40) at

16.18mg/l. Slightly elevated ammoniacal nitrogen concentrations were recorded for the

samples from probeholes WS12 in the north western part of the site and WS15 in the centre of

the site at 1.1mg/l and 1.2mg/l respectively. No elevated PAH levels were recorded.

2.7 Ground Investigation 2007

The ground investigation carried out in November and December 2007 was designed to extend

the findings of the 2006 investigation. The investigation was designed to:-

• clarify the volume of contaminated materials on the site;

• investigate the ground conditions beneath Boult’s land and the north eastern area of

the site for which access was not possible in 2006;

• confirm the groundwater quality and the impact of contaminated ground at the site on

groundwater;

• provide sufficient data to facilitate human health and groundwater risk assessments

and the design of a contaminated land remediation strategy; and,

• provide geotechnical information for foundation design purposes.

The investigation consisted of the excavation of 4 trial pits and the drilling of 7 probeholes using

a window sampling technique and 7 ground investigation boreholes using a percussive, cable –

tool drilling technique. Samples of the materials proved in the trial pits, probeholes and

boreholes were submitted for both geotechnical and geochemical analysis. The trial pits were

excavated to a depth of 4m. The probeholes were drilled to depths of 4m to 6m and the

boreholes to 10m. The logs of the trial pits, probeholes and boreholes are provided at

Appendix B. The locations of the trial pits, probeholes and boreholes are shown on Figure 2.5.

Following completion of the drilling, groundwater samples were collected from three probeholes

and three boreholes as part of a programme of environmental monitoring.

An assessment of the results of the geo-technical testing of the soil samples to inform the

foundation designs is provided in a separate document and is not considered in the

contaminated land assessment.

Page 12: Contaminated Land Remediation Strategy FINAL · Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 3 1.1 Background Faber Maunsell Limited is commissioned

Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 9

A total of six soil samples were submitted for analysis of the suite of contaminants listed in

Table 2.1. The samples were collected from locations in the northern part of the site, which

was not assessed in the 2006 investigation. The laboratory data sheets for the soils analysis

are presented at Appendix C. The six groundwater samples were analysed for the parameters

listed in Table 2.2 and the laboratory data sheets are provided at Appendix D. An assessment

of the ground and groundwater conditions based on the findings of both the 2006 and 2007

investigations is provided in Section 3.

Table 2.1 Soils analysis suite

Arsenic, cadmium, chromium, lead, mercury, selenium, boron (water soluble), copper, nickel, zinc, polyaromatic hydrocarbons (PAH16 speciated by GC-MS), total petroleum hydrocarbons (TPH by GC-FID), sulphide, sulphate (water soluble) and pH. SVOC and VOC. Asbestos. Soil Organic Matter.

Table 2.2 Groundwater analysis suite

Arsenic, cadmium, chromium, lead, mercury, selenium, boron, copper, nickel, zinc, polyaromatic hydrocarbons (PAH16 by GC-MS), cyanide, extractable petroleum hydrocarbons (EPH by GC-FID), sulphide, sulphate and pH.

2.8 Site Condition Survey

Prior to the ground investigation, Faber Maunsell Limited was commissioned by Rugby Borough

Council to undertake a health and safety risk assessment of the cattle market site. The

purpose of the survey was to identify to the Council hazards currently on the site and the

potential risk posed by these hazards to the health and safety of those entering the site and to

enable the Council to take appropriate precautions to reduce the health and safety risks

following closure of the Cattle Market.

The main conclusions of the survey were:-

• the need to prevent as far as possible unauthorised access to the site.

• the need to restrict access to buildings on the site.

• the need to install appropriate signage to identify potential risks.

• the need to review the existing Type 3 asbestos survey to clarify potential risks

associated with the known presence of asbestos on the site.

Further details of the survey are provided in the Faber Maunsell report of September 2007.

Page 13: Contaminated Land Remediation Strategy FINAL · Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 3 1.1 Background Faber Maunsell Limited is commissioned

Ground and Groundwater Conditions

Page 14: Contaminated Land Remediation Strategy FINAL · Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 3 1.1 Background Faber Maunsell Limited is commissioned

Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 11

3.1 Geology.

The geology of the site has been assessed from an interpretation of the BGS plans and the

results of the ground investigations carried out in 2006 and 2007. The site is underlain by a

variable thickness of made ground, overlying superficial deposits which rest on the Jurassic

Lias Clay.

The made ground comprises a surface concrete slab and associated sub-base layer over much

of the northern half of the site and in the southern area by mainly an asphaltic gravel which

forms the surface of the car parking areas. The sub-base comprises a granular aggregate of

brick, clinker, ash and gravel. The made ground typically is approximately 0.5m thick, apart

from the north eastern part of the site where the made ground is 1.0m to 2.4m thick. Figure 3.1

shows the variation in the thickness of the made ground across the site.

The superficial deposits beneath the made ground consist of a mixture of stony clay and sands

and gravels varying in thickness between 1.1m in trial pit TP30 and 3.95m in borehole CP26.

Locally the sands and gravels are very thin or absent and the made ground rests directly on the

Lias Clay, as in probehole WS15 and trial pit TP22. Figure 3.2 shows the thickness of the

sands and gravels across the site. Figure 3.3 shows the depth to the surface of the Lias Clay.

In the southern part of the site, the superficial deposits consist principally of a stiff, brown and

grey stony clay. From Figure 3.3, it is interpreted that the surface of the Lias Clay typically is

more than 1.5m below the existing ground level and increases to the north of the site to more

than 4.5m.

Sands and gravels are developed mainly below the central and northern parts of the site. The

sands and gravels thicken to the north. In Boult’s land in the north western part of the site, the

sands and gravels are 2.6m to 4m thick and consist of a medium-dense, orangish-brown clayey

sand with sandstone and flint gravel. In this area the surface of the Lias Clay is at a depth of up

to 4.7m.

The sands and gravels are interpreted as a river terrace deposit associated with the River Avon

located to the north of the site. Figure 3.4 shows a geological cross-section running north-south

through the site. To the north of the site, the land falls by approximately 5m. The BGS

1:10,000 scale plan shows that the Lias Clay crops out at the base of the slope to the north of

the site.

The Lias Clay which underlies the superficial deposits consists of a firm to stiff, grey clay and

silt, locally grading in to a weak mudstone. At the junction with the clay, the overlying sands

and gravels are described as soft, possibly reflecting the presence of groundwater perched on

the clay.

3.2 Soil Chemical Results

A limited number of soil samples were analysed as part of the 2007 investigation. In the 2006

investigation, 30 soil samples had been analysed. In the recent investigation, six soil samples

were submitted for analysis from five locations in the northern half of the site, principally where

data was lacking from the 2006 study. The laboratory data sheets for the 2007 samples are

provided at Appendix C. A summary of the laboratory analyses for both sets of samples is

provided in Table 3.1.

Based on the results of the laboratory analyses of the soil samples, a risk assessment was

carried out to determine the potential impacts on human health. Soil Guideline Values (SGVs)

published by DEFRA as part of the CLEA programme, have been used to indicate the potential

risks to human health. At the time of preparing this assessment, ten SGVs have been

published.

3 Ground and Groundwater Conditions

Page 15: Contaminated Land Remediation Strategy FINAL · Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 3 1.1 Background Faber Maunsell Limited is commissioned

Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 12

As the site redevelopment proposals include residential usage, the generic model ‘residential

with plant uptake’ has been used in the assessment. This is considered the most appropriate

model for use in screening the soils contaminant concentrations at the site. The recorded

concentrations of contaminants have been compared against the SGVs derived for a residential

with plant uptake land use.

Where available, the SGVS have been used to indicate the potential chronic risks to human

health. In the absence of an SGV for a particular contaminant, Soil Screening Values (SSV)

have been developed in accordance with the Environment Agency and DEFRA Contaminated

Land Reports CLR 9 and 10 and the CLEA Briefing Notes 1-4.

For the phytotoxic metals of copper, zinc and boron, which rarely pose a risk to human health

unless present in very high concentrations, alternative guidance values have been used. The

copper and zinc concentrations have been compared against guidance values specified in the MAFF document ‘Code of Good Agricultural Practice for the Protection of Soil’’(1993) In this

document, a guidance concentration of 200mg/kg copper and 300mg/kg zinc is specified for

soils with pH above 7.

There currently is no published guidance level for boron in soils. Previously trigger levels were

specified in the now-withdrawn ICRCL 59/83 guidance document. Whilst it is recognised that

the ICRCL guidance no longer is used, in the absence of alternative acceptable guidelines it is

considered that the former ICRCL guidance level of 3mg/kg provides an initial screening value

for boron.

Guidance on polycyclic aromatic hydrocarbons (PAH 16) also was provided in the ICRCL 59/83

document. However, emphasis is now placed on the individual compounds, such as

benzo(a)pyrene [B(a) P], a potential carcinogen. The acceptable concentration of B(a)P varies

according to the individual site conditions. Discussions with the National House Building

Council and experience from other similar situations suggest that an acceptable B(a)P

concentration for a residential end-use is in the range 1mg/kg-2mg/kg.

For the Rugby Cattle Market site, the former ICRCLl trigger value of 50mg/kg for PAH (16) has

been used as an initial screening value with a more specific assessment placed on the B(a)P

concentration, adopting a conservative guidance value of 1mg/kg.

The analysis of the samples taken in 2006 showed elevated hydrocarbon contamination of the

made ground, particularly in the south eastern part of the site associated with the surface layer

of asphaltic gravel on the car parking area. Elevated metal concentrations also were recorded.

In the 2007 study, the soil samples analysed were all from the sub-base underlying the

concrete hardstanding of Boult’s land and the cattle market. In contrast to the 2006 samples,

none of the samples showed evidence of significant contamination.

For the majority of the 2007 samples, the reported metal concentrations were significantly

below the CLEA and MAFF soil guidance values. Arsenic concentrations exceed the CLEA

SGV of 20mg/kg in two samples from probeholes WS31 and WS33 on Boult’s land, with

concentrations of 33mg/kg and 44mg/kg respectively. The sample from probehole WS31 also

recorded a high zinc concentration of 500mg/kg, above the MAFF guideline value of 300mg/kg.

None of the other soil samples recorded metal concentrations above the guidance levels, with

many of the samples recording levels at only a fraction of the trigger values.

None of the six samples analysed recorded elevated hydrocarbon levels. Total extractable

petroleum hydrocarbon (EPH) varied between 8mg/kg and a maximum 110mg/kg in the sample

from probehole WS33 at 0.4m depth. The total hydrocarbon levels are significantly lower than

recorded in 2006. Total PAH (16) concentrations also were low varying from less than

0.1mg/kg to a maximum 25mg/kg, in the sample from trial pit TP22 on the northern edge of the

site at a depth of 0.5m. The B(a)P concentration varied between less than 0.1mg/kg and a

maximum 12mg/kg in the sample from probehole WS27 at 0.2m depth.. Probehole WS27 is

located in the eastern part of the cattle market area.

The absence of significant contamination of the made ground beneath the northern part of the

site, beneath the concrete hardstanding, is consistent with the findings of the 2006 survey, in

which the bulk of the contamination was attributed to the asphaltic gravel covering the car

parking areas. The asphaltic gravel is absent in the northern part of the site.

Page 16: Contaminated Land Remediation Strategy FINAL · Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 3 1.1 Background Faber Maunsell Limited is commissioned

Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 13

Asbestos was not identified in any of the six soil samples analysed in the 2007 investigation.

Table 3.1 Summary of the soil analytical results – 2006 and 2007

Parameter Min Max

Guidance

Values

(SGV/MAFF1/

ICRCL2/DIV

3)

No. of

samples

No. of

samples

above

guidance

values

No of

samples

below limit

of detection

Arsenic 6.4 56 20 36 8 0

Boron <0.5 8.7 32

36 8 11

Cadmium <0.5 1.9 2 36 0 8

Chromium 11 69 130 36 0 0

Copper 7.3 690 2001

36 2 0

Lead 7.9 1800 450 36 3 0

Mercury <0.3 2.8 8 36 0 28

Nickel 5.9 110 50 36 3 0

Selenium <1 4.5 35 36 0 12

Zinc 27 850 3001

36 3 0

Free cyanide <5 203

30 0 30

Total cyanide <5 1/203

30 0 30

pH 7.3 11.9 36 0 N/A

Sulphide <10 1700 2502

30 1 10

Thiocyanate <5 502

30 0 30

TPH (C10-C40) 8 17,000 50/50003

16 8/4 0

PAH(16) <0.1 1542.26 502 36 12 9

B(a)P <0.1 120 1 36 17 11

Benzene <0.01 <0.025 0.05/13

16 0/0 16

Toluene <0.01 <0.025 3 16 0 16

Ethyl-

benzene <0.01 <0.025 9 16 0 16

Xylene <0.01 <0.025 6 16 0 16

MBTE <0.025 n/a 10 0 10

Phenol <0.1 0.26 78 36 0 35

All units as mg/kg except pH.

KEY

1 – MAFF Soil Guidance value

2 – ICRCL 59/83 trigger value

3 – Dutch action/intervention values

Page 17: Contaminated Land Remediation Strategy FINAL · Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 3 1.1 Background Faber Maunsell Limited is commissioned

Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 14

3.3 Hydrogeology

3.3.1 Groundwater level

Groundwater is present in the sands and gravels. It is considered that the groundwater in the

sands and gravels is perched on the underlying low permeability Lias Clay. A programme of

groundwater level monitoring has been carried out and the results of the monitoring are

presented at Appendix E. Based on the information collected on 9 January 2008, a

groundwater contour plan for the sands and gravels has been prepared (Figure 3.5). The

groundwater depth varies across the site from 0.5m below ground level (bgl) in borehole CP21

in the north eastern part of the site to approximately 3mbgl in probehole WS31 in the north

eastern corner of the site. Groundwater in the sands and gravels flows in a north north

westerly direction from 96.2mAOD in probehole WS7 in the car park in the south east of the site

to 92.8mAOD in probehole WS31 in the north western corner of Boult’s land.

3.3.2 Groundwater quality

Groundwater samples taken in the 2006 investigation showed evidence of slight contamination

of groundwater in the sands and gravels, principally by hydrocarbons. Figure 4.5 of the Faber

Maunsell report of March 2006 provides a summary of the results of the groundwater sampling.

As part of the 2007 investigation, six groundwater samples were collected. Four samples were

collected from locations in the northern part of the site (CP21, WS23, WS27 and WS31), down

hydraulic gradient of the area of known soil contamination. The remaining two samples were

collected from boreholes CP32 and CP36 located in the car parking areas in the south of the

site. The samples were analysed for the suite of parameters listed in Table 2.2. The laboratory

data sheets are provided at Appendix D.

The results of the analyses show no evidence of groundwater contamination. Total

hydrocarbons were not recorded above the limit of detection of 0.01mg/l in any of the samples.

Individual PAHs also were not recorded above the limit of detection of 0.1µg/l. The

concentrations of the remaining parameters were compared against Environmental Quality

Standards (EQS) published by the EA. As there currently are no EQS published for

groundwater, the EQS for ‘freshwaters’ were used for assessment purposes. For the majority

of the metal and metalloids, the recorded levels were at or below the respective limits of

detection and below the EQS.

The groundwater is slightly acidic at pH 6.5 to 6.9, apart from the sample from borehole CP21 on the northern edge of the site, which recorded an anomalous alkaline pH of 11.6. The sample

taken from borehole CP36 in the southern part of the site recorded an anomalously high

sulphate concentration of 580mg/l, compared with the other samples in which the sulphate

concentration varied between 50mg/l and 82mg/l.

Based on the results of the groundwater quality monitoring in December 2007, it is concluded

that there is no evidence of contaminated groundwater beneath the Rugby Cattle Market site.

Elevated concentrations of contaminants observed in the made ground are not reflected in the

groundwater. Accordingly, it is concluded that contaminants in the made ground are present in

non-mobile forms and do not present a risk to groundwater quality.

3.4 Ground gases

Ground gas monitoring was carried out at the site on three occasions. The results of the

monitoring are provided at Appendix E.

The results show that methane above the limit of detection of 0.1%v/v was not detected on the

site. Carbon dioxide, above the limit of detection, was recorded in seven of the monitoring

points on one or more occasions. The highest concentration of 5.9%v/v was recorded in

probehole WS14 in the northern part of the site. None of the monitoring points recorded an

elevated gas flow rate. Gas flow rates were negligible on all occasions, with a maximum flow

rate of 0.4 l/hour.

No carbon monoxide or hydrogen sulphide was recorded on the site.

Page 18: Contaminated Land Remediation Strategy FINAL · Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 3 1.1 Background Faber Maunsell Limited is commissioned

Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 15

Guidance documents state that if methane exceeds 1%v/v and/or carbon dioxide exceeds

5%v/v together with a measurable gas flow rate, gas control measures should be incorporated

in the building design to protect the building from the ingress of ground gases. Carbon dioxide

above 5%v/v has been recorded in probeholes WS11 and WS14. Based on the results of the

monitoring, it is considered in the absence of elevated gas levels together with the absence of

elevated gas flow rates that no gas control measures will be needed on the site.

3.5 Summary

Based on the results of the ground investigations carried out in 2006 and 2007, it is considered

that there is ground contamination on the site which presents a risk to human health and a

potential constraint to the proposed development. The highest levels of ground contamination

are associated with the thin surface layer of made ground principally in the car parking areas in

the south and east of the site.

There is no evidence of groundwater contamination in the sands and gravels beneath the site.

It is considered that the contaminants recorded in the made ground on the site are present in

immobile forms and do not present a risk to the quality of the groundwater.

No methane has been recorded at the site. Slightly elevated carbon dioxide levels, above the

trigger level of 5%v/v, have been recorded locally on the site. However as the gas flow rates

are negligible, it is considered that the carbon dioxide levels do not present a major risk.

Page 19: Contaminated Land Remediation Strategy FINAL · Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 3 1.1 Background Faber Maunsell Limited is commissioned

Conceptual Model and Risk Assessment

Page 20: Contaminated Land Remediation Strategy FINAL · Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 3 1.1 Background Faber Maunsell Limited is commissioned

Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 17

4.1 Introduction

Qualitative and quantitative risk assessment were carried out to identify the principal aspects

concerning the presence of contamination at the site and its likely impacts.

To assess the potential environmental impacts associated with the proposed development, a

qualitative risk assessment has been undertaken using the source-pathway-receptor approach

promoted by DEFRA and the Environment Agency. For there to be an identifiable risk, not only must there be contaminants present on the site (source) ie contaminated ground, leachate,

landfill gas but also there must be a receptor and a pathway which allows the source to reach

the receptor. All three elements must be present to form a pollutant linkage before there can be

a potential risk to specific receptors. In accordance with standard practice, a conceptual model

of the potential or actual pollutant linkages was developed for the proposed scheme, to

evaluate the likely impacts.

4.2 Conceptual Model

A conceptual model of the Rugby Cattle Market site has been developed based on the findings

of the 2006 and 2007 investigations and the results of subsequent environmental monitoring.

The site is underlain by a generally thin layer of made ground which overlies a variable

thickness of sands and gravels and clays. The sands and gravels rest on the Lias Clay. The

sands and gravels are water-bearing and groundwater beneath the site flows in a north north

westerly direction.

4.2.1 Sources

The principal source of contamination on the site is the thin layer of made ground, which locally

contaims elevated levels of contaminants, principally hydrocarbons.

4.2.2 Receptors

The main receptors which may be susceptible to contamination arising on or beneath the site

are:-

• Construction staff involved in the proposed redevelopment of the site;

• Future site occupants and end-users;

• Groundwater in the sands and gravels; and,

• Surface water features, including site drainage and the River Avon.

4.2.3 Pathways

The principal routes by which the source of contamination may impact on sensitive receptors

include:-

• Inhalation of dust and contact with or ingestion of contaminated soils;

• Ingestion of plants/vegetables grown on the site;

• Exposure to rainfall and mobilisation of soluble contaminants during construction;

• Leaching of soluble contaminants to groundwater in the sands and gravels; and,

• Movement of soluble contaminants in the groundwater to the surface drainage system.

Based on the conceptual model, it is concluded that currently there are plausible pollutant

linkages on the site which potentially pose a risk to human health and controlled waters

(surface water and groundwater). The results of the groundwater quality monitoring

demonstrate that the linkage to groundwater has not been realised. However, the presence of

4 Conceptual Model and Risk

Assessment

Page 21: Contaminated Land Remediation Strategy FINAL · Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 3 1.1 Background Faber Maunsell Limited is commissioned

Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 18

elevated contaminant levels in the made ground across parts of the site render the site currently

unsuitable for the proposed development in the absence of remedial measures. The principal

area of concern is the residential development, including the garden areas, proposed for the

eastern and south eastern parts of the site, where there is known hydrocarbon contamination of

the made ground.

In order to render the site suitable for the proposed development, remedial measures will be

required to remove the potential risks to human health from the contaminated soils present on

the site. The contamination is limited to the made ground and, in particular, to the asphaltic

gravel surfacing of the car parking areas.

4.3 Remediation Strategy

4.3.1 Methodology

The principle of any remediation strategy adopted at the site is to disrupt any pollutant linkages

between the source of contamination and receptors (site construction workers and end users of

the site). The remediation scheme also will be developed to re-use as much material as

possible and thereby minimise the volume of material removed off-site. Based on a preliminary

assessment of the proposed development, it is estimated that there is a surplus volume of

material on the site of approximately 10,000m3.

Based on the results of the soils analyses, it is considered that contamination generally is

restricted to the surface layer of made ground. Apart from the north eastern corner of the site,

the made ground typically is less than 1m thick and consists of concrete slabs and sub-base

beneath Boult’s land and much of the cattle market; asphaltic gravel across the car parking

areas in the south and east; and, general fill. Including the concrete slabs, it is estimated that

the volume of made ground on the site is approximately 29,000m3, of which the concrete slabs

comprise approximately 4,600m3.

Made ground contaminated by hydrocarbons in the southern and eastern parts of the site

covers an area of approximately 21,800m2 and has an estimated volume of approximately

9950m3. Chemical analysis of the sub-base materials beneath the concrete slabs suggests that

this material is uncontaminated and does not pose a risk to human health. This material has a

volume of approximately 14,200m3. A summary of the made ground is provided in Table 4.1. It

is considered that both the concrete and the underlying sub-base are suitable for re-use on the

site with no restrictions.

Table 4.1 A summary of the made ground

Made ground Estimated volume

(m3)

Concrete slabs 4,600

Sub-base to concrete slabs and other

uncontaminated fill

14,200

Contaminated ground – principally car park

surfacing

9,950

TOTAL 28,750

It also should be recognised that there are negligible soils on the site and that it will be

necessary to import soils for the residential gardens, the area of public open space and the

‘green’ landscaped areas.

Page 22: Contaminated Land Remediation Strategy FINAL · Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 3 1.1 Background Faber Maunsell Limited is commissioned

Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 19

4.3.2 Remediation Strategy

The most sensitive areas from a ground contamination perspective are in the eastern part of the

site proposed for residential end-use, particularly the 26 houses with gardens, as these present

a greater risk of exposure of end-users to the contaminated ground. Other than the two houses

at the northern end of this area, the made ground underlying the proposed residential area is in

the order of 0.5m thick. There is a need to import subsoil and topsoil to form the gardens to the

houses. The soils in the garden areas will consist of a minimum 0.1m topsoil and 0.5m subsoil.

It is proposed that across the whole of the proposed residential area, the surface is lowered by

a minimum of 0.5m, which will result in the removal of the majority of the contaminated ground.

To achieve the final profile of the residential area, clean subsoil and topsoil to a minimum

combined thickness of 0.6m will be imported to the garden areas. The landscaping areas will

be restored by a minimum 0.1m topsoil overlying 0.2m subsoil and 0.2m of clean material

recovered from other parts of the site. The roads, car parking areas and the ‘squares’ will

include a sub-base layer of crushed concrete and other clean materials recovered from the site.

Where the contaminated ground is greater than 0.6m thick in the eastern part of the site, the

contaminated material will be excavated to a minimum depth of 0.6m and clean material

covered with subsoil and topsoil will be replaced. The presence and thickness of the soil layers

will depend on the proposed use for that specific part of the site; such as residential gardens,

car parking areas etc.

The contaminated materials removed from the eastern part of the site will be deposited in the

western half of the site beneath the area of public open space in the central part of the western

area and beneath the community area, the squares and the landscaped areas around the

Nursing Home. Where the contaminated material will not be covered by an impermeable layer,

the material will be covered by a minimum thickness of 0.5m of topsoil, subsoil and clean

materials. Covering of the contaminated materials either beneath hardstanding or a minimum

0.5m thickness of clean cover will break the pollutant linkage between users of these parts of

the site and the contaminant source and thereby reduce the risk to human health.

Whilst every effort will be made to minimise the volume of material removed from the site for

disposal, based on a preliminary assessment of the development proposals, it is estimated that

there is a surplus of material on the site of approximately 10,000m3. This material will be

uncontaminated and will be suitable for re-use, recycling or for disposal at a site which has a

registered exemption from Waste Management Licensing.

Whilst much of the site has been assessed for its contaminant potential, the risk of excavating

currently unidentified small areas of contamination cannot be discounted. In the event that

excavations prove additional areas of visually contaminated ground consistent with

hydrocarbon contamination, the material will be isolated on the site and samples taken for

laboratory testing for the contaminant suite in Table 4.2. The management of these materials

will be determined, based on the results of the laboratory testing.

It is considered that the proposed methodology for removing contaminated materials from the

sensitive residential area of the site and covering this material beneath impermeable cover or

beneath a minimum 0.5nm of clean soil cover in less-sensitive areas effectively will break the

pollutant linkage and minimise the risk of adverse impacts on human health.

4.4 Soils Testing

It will be necessary to ensure that the development of the site does not cause an increased risk

to human health or to groundwater. All material imported to the site, in particular subsoil, will be

tested to determine its suitability for use on the site in both residential gardens and landscaping

areas. The imported material will be tested for the contaminant suite listed in Table 4.2, as part

of a validation testing exercise. The purpose of the testing is to validate the quality of any

materials imported to the site and to determine the contaminant concentrations of materials

which may be retained in-situ or redistributed across the site.

Page 23: Contaminated Land Remediation Strategy FINAL · Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 3 1.1 Background Faber Maunsell Limited is commissioned

Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 20

Table 4.2 Validation and contamination testing suite for soils

Arsenic, cadmium, chromium, lead, mercury, selenium, boron (water soluble), copper, nickel, zinc, polyaromatic hydrocarbons (PAH16 speciated by GC-MS), total petroleum hydrocarbons (TPH by GC-FID), sulphide, sulphate (water soluble) and pH. SVOC and VOC. Asbestos. Soil Organic Matter.

4.5 Compliance with Legislation

The need to regrade the made ground and to re-deposit contaminated materials in other areas

of the site to achieve the development site levels, potentially is the subject of Waste

Management Licensing. It is recommended that confirmation is obtained from the Environment

Agency that this operation is exempt from Waste Management Licensing or complies with its

policy on necessary regrading works.

Any materials removed off-site for treatment or disposal should be managed in accordance with

the Duty of Care. The deposit of any contaminated materials to landfill can benefit from an

exemption from Landfill Tax, provided that this is obtained in advance of materials leaving the

site.

4.6 Ground gases

The results of ground gas monitoring at the site have shown that methane is not present above

the limit of detection and that carbon dioxide is slightly elevated locally across the site.

However gas flow rates are very low, with a maximum recorded flow of 0.4 l/hour.

Guidance on the risks posed to developments from the presence of ground gases is provided in the NHBC document of March 2007, entitled ‘Guidance on Evaluation of Development

Proposals on Sites where Methane and Carbon Dioxide are Present’. Based on the risk

assessment in Table 14.1 of the document, and the maximum recorded carbon dioxide

concentration of 5.9%v/v, a gas screening value of 0.024 l/hour is derived. Using this gas

screening value as an initial guide, it is considered that the ground gas conditions at the site do

not pose a significant risk to the development. Guidance provided in Table 14.2 of the NHBC

document suggest that either no gas protection measures are required or that only low-level

gas protection measures will be necessary.

Only limited ground gas monitoring has been carried out at the site. In order to confirm the

need, if any, for gas protection measures it is recommended that further ground gas monitoring

for methane, carbon dioxide, oxygen, carbon monoxide and hydrogen sulphide together with

gas flow is carried out monthly at the site.

4.7 Soakaways

As part of the scheme development, there is a proposal to use soakaways to dispose of surface

drainage. The effectiveness of soakaways depends on the thickness of the unsaturated zone

and the nature of the underlying materials. It is considered likely that the sands and gravels

provide conditions suitable for the use of soakaways.

However, in the southern part of the site, the sands and gravels are relatively thin and it is

considered unlikely that soakaways will be effective in this part of the site. The sands and

gravels thicken to the north and the groundwater table typically is at a depth of up to

approximately 3m. It is likely that soakaways in the northern part of the site will be effective.

However, the land surface to the north of the site falls significantly. Geological information

suggests that the Lower Lias Clay outcrops to the north of the site. Accordingly, it is considered

likely that there is a seepage face to the north of the site at the junction between the sands and

gravels and the Lias Clay. There is a risk that additional discharges to the sands and gravels

through soakaways may increase the rate of seepage, potentially causing flooding to the land to

the north of the site.

Page 24: Contaminated Land Remediation Strategy FINAL · Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 3 1.1 Background Faber Maunsell Limited is commissioned

Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 21

If the proposal to use soakaways is progressed, it is recommended that soakaway tests are

carried out to confirm the suitability of the underlying geology and that a detailed assessment of

the drainage on the lower land north of the site is carried out to assess the likely impacts.

Page 25: Contaminated Land Remediation Strategy FINAL · Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 3 1.1 Background Faber Maunsell Limited is commissioned

Conclusions and Recommendations

Page 26: Contaminated Land Remediation Strategy FINAL · Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 3 1.1 Background Faber Maunsell Limited is commissioned

Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 23

5.1 Conclusions.

Based on an appraisal of the results of the two ground investigations carried out at the site in

2006 and 2007, the following conclusions can be drawn:-

• The site has been used as a livestock market and associated activities since

approximately 1878.

• The market area occupies the central part of the site, owned by Rugby Borough

Council with mainly hardstanding and car parking areas in the east and south. The

northern part of the development area is under third party ownership.

• The surface of the site is covered by a layer of made ground, typically in the order of

0.5m thick but locally up to 2.4m. The made ground consists of a mixture of concrete

and underlying sub-base layer and fill (asphaltic gravel) used to surface the car parking

areas in the south and east of the site.

• The made ground overlies superficial deposits of sands and gravels with clays. The

superficial deposits overlie the Lias Clay.

• The sands and gravels thicken to the north west where they are up to 4m thick.

• The sands and gravels are water-bearing. The groundwater depth varies between

0.5m and 3m below ground level. Groundwater in the sands and gravels flows in a

north north westerly direction.

• The made ground on the site locally is contaminated, mainly by hydrocarbons in the

southern and eastern parts of the site, where contamination is associated with the

surface cover to the car parks of asphaltic gravel. Locally, elevated metal

concentrations, in particular arsenic, lead, nickel and zinc also are present in the made

ground.

• There is no evidence of contamination of the groundwater in the sands and gravels.

• Contamination present locally in the made ground does not pose a risk to groundwater

quality but locally does pose a constraint on the proposed development of the site,

particularly for those areas of proposed residential development. It is concluded that

remedial measures are required to render the site suitable for the proposed

development.

• There is no evidence for the presence of ground gases at elevated concentrations on

the site. Gas flow rates are low and it is considered that at worst only low level gas

protection measures will be required.

• The proposed contaminated land remediation strategy includes the need for the

redistribution of contaminated materials around the site away from the areas proposed

for residential development. The contaminated materials should be placed below lower

sensitivity areas in the west of the site, such as car parks, landscaped areas or floor

slabs or in open spaces provided that the materials are covered with clean soils to

disrupt any pollutant linkages.

5. Conclusions and Recommendations

Page 27: Contaminated Land Remediation Strategy FINAL · Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 3 1.1 Background Faber Maunsell Limited is commissioned

Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 24

5.2 Recommendations

The contaminated land remediation strategy has been prepared to minimise the risks to human

health. In order to confirm the suitability of the strategy, it is recommended that:-

1. once the development proposals have been finalised, the contaminated land strategy should

be reviewed to ensure that the detailed remediation proposals reflect the final development of

the site.

2. ground gas monitoring at the site is continued on a monthly basis to identify variations in the

gas (methane, carbon dioxide, oxygen, carbon monoxide and hydrogen sulphide)

concentrations and flow rates and the need for the inclusion of gas protection measures as part

of the final scheme.

Page 28: Contaminated Land Remediation Strategy FINAL · Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 3 1.1 Background Faber Maunsell Limited is commissioned

Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 25

Appendix A

Site Masterplan 2007 (SK16.11.07A)

Page 29: Contaminated Land Remediation Strategy FINAL · Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 3 1.1 Background Faber Maunsell Limited is commissioned

Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 26

Appendix B

Trial pit, probehole and borehole logs 2007

Page 30: Contaminated Land Remediation Strategy FINAL · Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 3 1.1 Background Faber Maunsell Limited is commissioned

Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 27

Appendix C

Laboratory data sheets for soil samples 2007

Page 31: Contaminated Land Remediation Strategy FINAL · Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 3 1.1 Background Faber Maunsell Limited is commissioned

Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 28

Appendix D

Laboratory data sheets for groundwater samples 2007

Page 32: Contaminated Land Remediation Strategy FINAL · Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 3 1.1 Background Faber Maunsell Limited is commissioned

Faber Maunsell Contaminated Land Remediation Strategy: Rugby Cattle Market 29

Appendix E

Groundwater level and ground gas monitoring results