futures park, bacup stage1 & 2 ground investigation for

Contaminated Land

Air Quality

Environmental Audit

Partnership No: OC 300776

Smith Grant LLP, Station House, Station Road, Ruabon, Wrexham, LL14 6DL

tel: 01978 822367 fax: 01978 824718 e-mail: [email protected] web: www.smithgrant.co.uk

Members: A F Smith (Chairman), K E Hawkins

Futures Park, Bacup

Stage1 & 2 Ground Investigation

For: Rossendale Borough Council

August 2013

R1841-R01-v2

Futures Park, Bacup Stage 1 & 2 Ground Investigation

Smith Grant LLP R1841-R01-v2 Final Environmental Consultancy 16

th September 2013

1

DOCUMENT CONTROL SHEET Report Title:

Futures Park, Bacup

Stage 1 & 2 Ground Investigation

Client:

Rossendale Borough Council

Report Reference Number:

R1841-R01

Issue

Final

Version:

Version 2

Report Date:

16th September 2013

Signed For Smith Grant LLP

Name Position Signature Date

Author

Briony Harvey MESci, MSc, CWEM, CSci

Consultant

16

th September

2013

Reviewer

B J Thomas BSc MSc MCIWEM CEnv

Partner

16th

September 2013

Document Revision Record:

Version Report Status Date Details of Revision

v1 draft 10th July 2013 draft for client comment

v1 final 12th august 2013 Final without changes

v2 final 16th September 2013 Alteration development proposals



th September 2013

2

CONTENTS

1. Introduction

2. Information Sources

3. Development History and Current Status

4. Site Characterisation

5. Preliminary Conceptual Site Model and Risk Assessment

6. Investigation Methodology

7. Investigation Observations

8. Investigation Results

9. Conceptual Model and Risk Assessment

10. Conclusions and Recommendations

DRAWINGS

001 Site Layout and Features

002 Historical Map, 1893



005 Historical Map, 1962-64


007 Site Investigation Locations

008 Development Constraints

APPENDICES

A Photographs

B Site Investigation Logs

C Chemical Analytical Results

D Gas/Groundwater Monitoring Results

E Geotechnical Report



th September 2013

3

1. Introduction

1.1. Rossendale Borough Council (RBC), instructed Smith Grant LLP (SGP) to undertake a combined

Stage 1 and 2 Ground Investigation of an area of land located to the south and west of the

Business Centre, Futures Park, Bacup to inform the proposed redevelopment of the site. The

investigation includes a contamination and geotechnical assessment of the ground conditions of

four parcels of land which are under consideration for use as a cycling centre and associated

infrastructure, Site details are:

Table 1.1: Site Details

Address Futures Park, Newchurch Road, Bacup, OL13 0BB

National Grid Reference 286422, 421605

Local Authority Rossendale Borough Council

Site Area 2.8 ha

Current Nature of Site Derelict land used informally for amenity purposes.

Planning Permission unknown

Proposed Use Cycling centre comprising car parking, commercial premises

and landscaping

Figure 1.1: Site Location (site boundary shown in blue)

Reproduced with the permission of the Ordnance Survey @Crown Copyright Licence No. 100005799

1.2. The site is subdivided into four separate areas referred to as Plots 1, 3, 4 and 5 (SGP understand

that Plot 2 was the area to the north of the River Irwell, east of the existing access road;

redevelopment of this area has been completed). Plot 1 is a separate parcel to the north of the

River Irwell, comprising a triangular parcel of land bounded by the site access road to the east, the



th September 2013

4

River Irwell to the south and Newchurch Road to the north. The remaining plots lie to the south of

the River Irwell; Plot 3 is the land to the west of the access road and Plot 4 to the east. Plot 5

comprises all the remaining land to the south beyond the end of the access road. The various Plot

boundaries are indicated on Drawing 001; these are based on an unscaled plan provided to SGP

and their accuracy cannot be verified so should be regarded as indicative rather than absolute.

1.3. Previous uses were originally agricultural land adjacent to the former channel of the River Irwell,

which was partially infilled following diversion, and various historical industrial uses. The site is

currently derelict; comprising areas of mainly unsurfaced open ground, with grass, weeds and

scrub, and some areas of mature trees. The site is currently used as informal amenity land and as

a route to and from the nearby way-marked cycleways around Lee Quarry to the south.

1.4. This report describes the Stage 1 (desk study and site inspection) and Stage 2 (intrusive

investigation) works undertaken by SGP in accordance with a brief agreed with the client. The

assessment methodology follows the framework described in the EA / DEFRA Contaminated Land

Report 11: ‘Model Procedures for the Management of Land Contamination’ 2004, containing a

review of readily available information on the environmental setting of the site and the site’s

previous and current uses with respect to potential risks to the environment or human health; a

preliminary site inspection; an intrusive investigation, the collection of soil and groundwater

samples for chemical and physical analysis and gas monitoring. This report contains a qualitative

risk assessment and where appropriate makes recommendations for further intrusive investigations

and remedial actions appropriate to the future use of the site.



th September 2013

5

2. Information Sources

2.1. The principle sources of information consulted in the preparation of this report include:

Table 2.1: Information Sources

date and reference author and source purpose and information content

Topography, geology, hydrogeology and hydrology

British Geological Survey Sheet 76 British Geological

Survey

Geological survey maps –Solid and Drift

OS map sheet 103 (Blackburn) Ordnance Survey Current site setting

HPA-RPD-033

http://www.ukradon.org/downloads/

Reports/Eng_Wales_Placenames.pdf

(accessed June 2013)

Radon Atlas of England

and Wales

mapping defining radon affected areas

in England & Wales

BRE 211 Radon: Guidance on

Protective Measures for

New Buildings, 2007

mapping identifying required radon

protective measures in England &

Wales

Historical data

various Ordinance Survey historical mapping at 1:2,500, 1:10,000,

and 1:10,560 from 1893 onwards.

Information review

www.environment –agency.gov.uk;

March 2011

Environment Agency general information on source

protection zones, flood risk zones,

pollution hazards, current an historical

landfills, water quality information

www.magic.gov.uk; March 2011 web-based interactive map containing

information on nature conservation

areas

Service Plans Various- gas, water,

drainage, electricity, oil

pipelines

Identification of constraints to

investigation locations

Development and Report Extracts RBC Synopses of existing features including

summaries of information reportedly

extracted from past geotechnical and

contamination assessments

2.2. Previous Investigations

2.2.1. SGP understands that site investigations assessing geotechnical and contamination issues have

been carried out on the site, however that the reports cannot be obtained. Furthermore, SGP

understand that remedial works have been carried out on the site to prepare it for redevelopment;

however any verification or validation reporting for these activities is also unavailable. A written

synopsis of the land condition for each development plot has been provided, which contains



th September 2013

6

information understood to have been derived from these sources, however its providence and

therefore accuracy is uncertain.

2.3. Site Inspection

2.3.1. A preliminary site inspection was undertaken by B J Thomas, Partner, on 24th

April 2013. This

comprised a walkover of the site and surrounding area.



th September 2013

7

3. Development History and Current Status

3.1. Historical Development

3.1.1. A summary of significant features, developments and land uses shown on historical Ordnance

Survey maps is provided in Table 3.1 below. Copies of selected maps are provided in Drawings

D02-D05, which also indicate the approximate site boundary as provided to SGP.

Table 3.1: Summary of Development History

map site surrounds

1849

1:10,560

The majority of the site was undeveloped

comprising fields and woodland. The

River Irwell is indicated forming a

meander crossing plots 3, 4 & 5. A

railway line with associated sidings ran

along the northern boundary of the site.

The majority of the site surroundings

comprised open land, with some

buildings to the immediate north.

1893

1:2,500

See Drawing D02

An unidentified building was indicated

located in the southern third of the site

accessed by a number of tracks. A break

of slope is indicated adjacent to the south

western corner of the River Irwell

indicating the ground sloped down to the

river. Plot 1 was occupied by Lee Mill.

Unlabelled buildings are present in the

northwest parts of the site.

The majority of the site surroundings

comprised open land, with tipped material

indicated to the immediate south of the

site extending onto the southern

boundary. A railway line shown as

constructed on a raised embankment

was indicated running along the western

site boundary split into several sidings.

Beyond the railway line a number of

terraced housing was present. A

reservoir is indicated to the north of the

site, beyond which terraced housing is

present.

1894

1:10,560

No significant changes identified No significant changes identified

1910

1:2,500

See Drawing D03

The former river channel had been

partially in filled in the north western

corner of the site where a stonecutter’s

yard is labelled. The rest of the channel

is still indicated as crossing the site but is

no longer connected to the Irwell. The

former unidentified small building and

associated tracks on the site was no

longer indicated; the main central areas

not containing any features.

The River Irwell had been canalised to its

current day configuration running along

the northern boundary of the site. An

increased amount of spoil appeared to

have been tipped to the south and west

of the site. An unidentified building was

located just beyond the railway branch

lines to the west of the site, the function

of which was unclear however a crane

appeared to be associated with it and

possibly additional tipped material.

1912

1:10,560




th September 2013

8

map site surrounds

1930

1:2,500

See Drawing D04

The southern parts of the former river

channel are no longer indicated and

appear to be in-filled by significant land-

raising throughout the southern areas.

The stone cutting works appears to have

expanded towards the south with a series

of smaller buildings constructed and a

single small building is indicated in the

northern part of the site

The reservoir to the north of the site was

no longer indicated and appeared to be

backfilled. A number of the mills in the

surrounding area which were previously

labelled as cotton mills are now shown as

producing shoes and slippers.

1930-32

1:10,560


1956

1:10,560

A large unspecified works is indicated

near the northern boundary

No significant changes identified

1962-1964

1:2,500

See Drawing D05

The mill present within plot 1 appeared to

have been extended and occupies most

of the area. An area on the eastern side

of plot 5 is indicated as a tip and

accessed by a track from the former

stone cutting works. A number of other

slopes indicate some regrading of the site

has taken place. The railway tracks

associated with the stone cutting works

(whose buildings are now unlabelled) are

no longer indicated.

No significant changes noted

1967-68

1:10,560


1987,

1:2,500

See Drawing D06

Incomplete coverage.

A hopper was indicated within plot 4

associated with the works building.

The buildings associated with the stone

cutting works in plot 3 are no longer

indicated with the exceptions of a single

‘works’ building.


1988-1992

1:10,000

A quarry is labelled within the main area

although its extent is not plotted.




th September 2013

9

map site surrounds

2000,Satelite

Imagery

Lee Mill (plot 1) had been demolished

and the area appeared to be disused.

No buildings remained across the

remainder of the site with the exception

of a single building in plot 3. The site

appeared to comprise a mixture of rough

hardstanding and mature/semi mature

trees. The tipped area in plot 5 appeared

to be clear of vegetation.


2003,Satelite

Imagery

Imagery was unclear however plot 4

appeared to have a large quantity of

material tipped on it, the origin of which

was unclear. The remaining building on

plot 3 had been demolished.


2005,Satelite

Imagery

The site appeared to be in the present

day state with the present day access

road and bridge having been constructed.

Tipped material on plot 4 was less

obvious and could have been removed or

regraded.

Plot 2 has the present day council offices

and car park constructed over the site.

3.2. Recent History

3.2.1. Anecdotal information from local sources has indicated that the plant associated with a hopper, as

indicated within the central area was a concrete batching plant.

3.2.2. The available historical records indicate that the bridge and access road linking Newchurch Road

with the central areas of the site was constructed around 2005 (between last two satellite images).

It is assumed that the reported site investigations and remediation works were contemporaneous

with these works, and that it was around this time that the information summarised in the synopses

of conditions for each plot was obtained.

3.2.3. It has also been reported that a treatment programme to eradicate a Japanese Knotweed

infestation has been carried out.

3.2.4. Without the full reporting, or confirmation that the reporting was critically reviewed by an

appropriately qualified and experienced person, this information can only be considered as

anecdotal. However, the descriptions still form a line of evidence which may be considered

alongside the other available information, particularly in informing the design of the intrusive works

carried out as part of the current assessment; a summary of the relevant information provided is

presented in the table below.



th September 2013

10

Table 3.2: Summary of Synopses of Ground Conditions provided by RBC

Plot 1 Existing features: highway embankment along north and eastern boundaries.

River wall structure along southern boundary.

No significant concentrations of contamination identified.

Plot 3 Past geotechnical reports comment on requirement for piled foundations, gas venting

and possible significant levels of contamination.

Extensive reinforced concrete slabs present along with bitumen.

A culverted watercourse together with inlet chamber.



Reinforced concrete slabs present across part of the site. Possible remnant

foundations.

Groundwater contamination not found to impact the river.



Groundwater contamination not found to impact the river.

An area of leather waste contamination present advised to be 550m2; possible

contamination by volatile organic compounds (VOCs) noted.

Possibly unstable embankment along southern boundary.

Badger sets present in the south eastern tree area and the Presence of Japanese were

noted.

3.2.5. The site plan produced by the Fowler Partnership architects on behalf of RBC, dated 19/04/2005

indicates an “Area of Waste Leather” at the base of the steep bank near the western end of the

sites southern boundary within Plot 5.

3.3. Present Land Condition

3.3.1. The following descriptions are based on notes and photographs taken by SGP staff during the site

walkover inspection and during the intrusive works and monitoring period:

Table 3.2: Present Land Condition

Site

Description

and

Boundaries

Plot 1 is separated from the adjacent carriageways to the north and east by a steep bank

with a level area some 4m lower than the roads. The banks are covered by scrub with the

level area grassed. To the south a retaining wall bounds a vertical 3m drop down to the

channel of the River Irwell. A number of access covers are present in the Plot and two

outfalls to the river are present, although no discharge was occurring at the time of the

inspection. Plot 3 comprises an area of undulating land with an overall slope down from

west to east. An area of tarmac is present and much of the remaining area is grassed apart

from an area of trees and scrub in the south; amongst these in the southwest corner, some

relict stone masonry walls with openings and the remains of stairs are present.

Plot 4 comprises land to the east of the access road, separated from the River Irwell to the

north by a strip of land around 8m wide and bounded by a wooden fence. The land is

generally level apart from numerous mounds of tipped soil, stone and generally inert waste



th September 2013

11

materials until the eastern boundary is reached, where a slope down to a low lying marshy

area is present. The southern boundary is occupied by a slope up into Plot 5. Plot 5 is the

largest area, spanning the length of the site from east to west, level with the boundary to

Plot 3 but dropping down a steep bank to the boundary with Plot 4 to the north. The land

rises steeply as the southern boundary is approached with a fence at the top of a large

steep bank marking the site’s southern boundary. A low lying area corresponding to the

location of the historical channel of the River Irwell crosses the western part of the Plot but

much of the eastern area is undulating with mounds, banks and ditches present.

Access Vehicle access to Plot 1 is obtained via a gate off a track to the west; pedestrian access can

be obtained by walking down the steep bank from the access road. Plots 3, 4 and 5 are

reached directly from the access road, although a bund of variable height and condition and

the bank in the south of Plot 5 restricts some vehicular access.

Services /

Wayleaves

Plans have been obtained for electricity, gas and drainage for the site. A number of

electricity and telephone utilities are shown within the access road (outside the area under

consideration), however a water pipe appears to leave the road footprint and cross the

southeast part of Plot 3 and an electricity cable appears to cross the northwest corner of Plot

4. A number of drains or sewers are shown on the utility plans and the site plan provided

crossing Plots 1, 3 and 4. A small watercourse to the east of Plot 4 appears to be partially

diverted into one of these drains and the route of the culvert corresponds to an outfall

discharging to the River Irwell to the north, however some of the flow continues within a

surface water channel alongside the eastern boundary of the site.

Rights of

Way

All parts of the site are readily accessed on foot and a number of informal pathways cross all

areas, as well as the cycle track crossing Plots 3 and 5 which leads to the nearby way

marked trails; however no public right of way is indicated on the contemporary maps

available.

Structures/

surfaces

The only above ground structures are several slabs at ground level and the remains of some

partially ruined walls with entrances in the southern part Plot 3, which also contains an area

of tarmac hardstanding. Some concrete slabs and pads are present in Plot 4 possibly

indicative of the former structures indicated on the historical mapping. Plots 3, 4 and 5 are

partially bounded by the existing access road.

Ecology SGP has not carried out a detailed ecological survey on the site but noted the presence of a

possible badger set in the south-east corner of the site. Badgers are a legally protected

species, with legislation including preventing disturbance of badger sets. A number of

mature/semi-mature trees are present within the site boundary, the majority of which are

located on the boundary between plots 4 and 5, the majority of plot 5 and the southern area

of plot 3; a number of stands of Japanese Knotweed were identified in this area.

3.4. Adequacy of Information

3.4.1. It is considered that the available information provides reasonable coverage of the site and

immediate surroundings. The information contained in the synopses of ground conditions for the

site cannot be verified but has been used to develop the preliminary site characterisation and

conceptual model used to inform the design of intrusive investigation.



th September 2013

12

4. Site Characterisation

4.1. The environmental setting of the site is described in Table 4.1 below:

Table 4.1: Environmental Setting

Surrounding

Landuse

The site is located in an area of largely mixed residential, commercial and industrial use.

Residential properties are to the immediate north of plot 1, along with some small

commercial premises as well as residential housing to the immediate west of plot 3. A mill

is located adjacent to the west of plot 1. The municipal offices are located within plot 2.

Surrounding land to the east and south comprises open land with some cycling tracks.

Topography Overall the topography of the site slopes upwards from the river towards the south;

however this is divided by a series of terraces. Plot 1 is generally level with steep

embankments along the northern and eastern sides sloping up to the road. Plot 3 slopes

generally downwards from the west to the east, however the western side is relatively level.

Plot 4 is generally level with several undulating mounds of spoil. Plot 5 slopes steeply

down from the south towards the north across the southernmost third of the site, then

generally levels off with a gentle slope towards the east. A slope down to the north is also

present on the boundary between Plots 4-5

Geology Solid geology comprises the Lower Haslingden Flags (sandstone) overlain by drift deposits

comprising alluvium (clay, silt, sand and gravels). Glacial Till is indicated on the eastern

and western sides of the site and may also be present below the alluvium.

Hydrogeology The site is classified by the Environment Agency as underlain by a secondary (A) aquifer

(sandstone bedrock). Superficial deposits are also within an area designated as

Secondary (A) aquifer. The aquifer is defined as highly vulnerable for groundwater,

however it is not specified whether this relates to the solid or drift aquifer.

Water

Resources

The site does not lie within a source protection zone, and no records are provided by the

Environment Agency Website with regard to groundwater abstractions occurring on or

within 250m of the site.

Flood Risk The site is not located in an area described as at risk of flooding from rivers, seas or

reservoirs.

Radon The maps provided in the Indicative Atlas of Radon in England and Wales show the site to

be within an area where between 3-5% of houses require gas protection measures

Nature

Conservation

No statutory nature conservation sites, such as SSSIs, SPAs etc have been identified

within 500m of the site, with the exception of Lee Quarry, which is a SSSI based on its

geology. SGP has not undertaken a detailed ecological survey; however a Japanese

Knotweed infestation was noted affecting parts of the site and spoil heaps possibly

indicating a badger set were identified during the walkover.

Excavation

and

Landfilling

Historical mapping indicates an infilled river channel passing through the centre of the site

and later phases of tipping appear to have taken place throughout the subsequent history

of the site, which largely pre-date waste licensing regulation. The Environment Agency

note are two landfills within a 1km radius of the site, one located 250m to the east of the

site (Land off Lane End Road) and one 250m to the south west (Cemetery tip). Both

landfills appear to be closed, with no further information supplied. Recent fly tipping of

materials on the site surface is evident.



th September 2013

13

5. Preliminary Conceptual Site Model and Risk Assessment

5.1. Sources of Contamination

5.1.1. The available information indicates the site to have mainly comprised open agricultural land and

wooded around a meander of the River Irwell until its diversion in the early 20th century, after which

the channel which the channel was in filled and/or allowed to silt up.

5.1.2. The southern parts of the site have remained undeveloped but have accepted tipped materials

during various stages of land raising and deposition. The large banks of material indicated on the

earlier maps both to the south and west of the site are likely to be comprised of ash and clinker

associated with the railway and sidings running along the site’s western boundary (plot 3) and the

large bank which forms the southern boundary to the site is evidently composed of similar

materials. Typically such materials are impacted by partial combustion products and are enriched

in metals and metalloids.

5.1.3. Other waste disposal activities pre-date the enactment of waste-licensing legislation or result from

unregulated activity, so are presumed to have been uncontrolled and potentially involving co-

deposition of domestic refuse and industrial wastes in an unengineered void and/or on the site

surface. A wide range of substances could therefore be present in the recorded tips areas. The

presence of tanks or drums of industrial wastes in particular could have resulted in the release of

oils, fuels, solvents, pesticides or other organic contaminants.

5.1.4. Leather waste has been reported in one area which may have resulted in the presence of a range

of pollutants associated with various tanning processes as well as generation of polluting leachate

and hazardous ground gas from the degradation of the organic material present. Leather waste

may also be associated with anthrax spores, which may remain viable for decades under certain

conditions.

5.1.5. The areas of recently fly-tipped materials may contain asbestos wastes, although none were noted

during the site walkover.

5.1.6. Other historical site uses such as the cotton mill (plot 1), concrete batching plant (plot 4) and

stonecutting yard (plot 3) are likely to be of limited potential to cause significant ground

contamination, although physical constraints to built development such as cellars/voids, substantial

foundations are likely to exist.

5.1.7. The site is in an area which historically contained significant heavy industry dominated by cotton

and leather mills and railway infrastructure; it is apparent that waste products from the surrounding

area have been deposited on the site; however the potential for migration of mobile (gaseous,

liquid or dissolved phase, or wind blown dust) contaminants from outside the site appears limited.



th September 2013

14

5.1.8. Natural sources of contamination are considered likely to be limited, although organic (peat)

deposits may be associated with the alluvial soils which can produce elevated concentrations

(although not typically significant volumes, pressures or flows) of hazardous ground gasses. The

site is within an area where between 3-5% of houses require gas protection measures.

5.1.9. The site has reportedly been subject to remediation earthworks to prepare it for redevelopment. A

comprehensive remediation programme undertaken in accordance with current best practice would

be expected to have treated any of the sources listed which present an unacceptable pollution risk

or major constraint to redevelopment of the site, although the level of remediation undertaken

would depend on the proposed use at the time. In the absence of any reporting for the works

undertaken the level of mitigation provided by the reported works cannot be confirmed therefore all

the potential sources listed are considered for a preliminary assessment of risks from ground

contamination.

5.2. Potential Targets

5.2.1. The proposed redevelopment is for infrastructure and some commercial premises to support

amenity use of the site and the surrounding area by cyclists. Future site users including visitors

and workers, including construction and maintenance workers, are considered to be potentially

vulnerable receptors for any near-surface soil contaminants. Exposure to soils and soil-derived

dusts could occur, although exposure frequency will be limited in the commercial/amenity scenario

under consideration.

5.2.2. SGP understand that the development proposals include two buildings and migration of gas or

vapour phase contaminants into the internal spaces is also considered, whether this is acute risks

such as build up of flammable gasses to and explosive atmosphere or long term health risks

through inhalation of toxic gases or vapours.

5.2.3. The potential for chemical attack on construction materials (primarily concrete and polymers)

should also be considered.

5.2.4. Some of the substances potentially present on the site can impact plant growth, although the

current vegetation cover indicates that this is only likely if sensitive species are introduced.

5.2.5. The shallow alluvial aquifer below the site may contain materials which have high potential

vulnerability to pollution and may serve as a pathway for shallow contamination migration; the

primary controlled waters receptor for the site, the River Irwell could also be impacted through

discharge from various drains, culverts and other preferential pathways which are known to exist

on the site. Deeper groundwater in the Coal Measures aquifer is considered less sensitive as most

groundwater movement is likely to provide baseflow to the river.



th September 2013

15

5.2.6. Residential housing to the west of the site may be affected if mobile contaminant sources exist,

together with a viable migration pathway towards the dwellings. The potential for development

activities to generate emissions (airborne dust/gas, groundwater discharge and surface runoff)

which extend beyond the site boundary must also be considered and while these are likely to peak

during the preparatory works and construction phase, activates which continue to cause

disturbance of the ground during the operational lifetime of the proposed development may also be

significant.

5.3. Ground stability

5.3.1. If the placement of waste materials on the site was carried out in an uncontrolled manner, which is

likely to have been the case, the made ground could variously contain oversized materials, voids

and deposits of degradable or otherwise physically unstable matter with associated risks from

differential settlement or collapse. The natural alluvium underlying the majority of the site may

result in weak soil conditions at various depths and there is a moderate potential for compressible

ground in all parts of the site.

5.3.2. Relict foundations and buried structures may exist in several locations which can present physical

obstructions to construction and case differential settlement, particularly if significant

compressibility of the natural soils can be anticipated.

5.3.3. Several steep slopes are present and at least one source indicates that stability of the slope

adjacent to the southern boundary of Plot 5 may be an issue.

5.3.4. Similar to the treatment of contamination sources, a comprehensive site remediation programme

would be expected to address some of the potential stability issues identified; the presence of

visible relict structures in parts of the site and old surface deposits indicates that at least some of

these potential constraints remain.

5.4. Preliminary Conceptual Site Model

5.4.1. A preliminary conceptual site model (CSM) was derived for the site describing the potential

contamination sources, pathways and receptors. The CSM was used to provide rationale for the

site investigation design and is summarised below in Table 5.3.



th September 2013

16

Table 5.3: Preliminary Conceptual Site Model

Receptor Source / Contaminant Pathway / Exposure Pollutant Linkage (in absence of mitigation) Further Investigation

metals / metalloids / asbestos /

organics may be present within

made ground; point sources may

also be present including pathogens

within areas of organic (leather)

waste

dermal contact / ingestion /

inhalation including dust

inhalation – short term exposure

Possible – extent, depth and nature of contamination

unknown; any contamination present at shallow

depths may pose a short term risk if exposed during

excavations

site investigation including shallow

soil sampling to determine extent

and nature of any contamination

1. humans – future

construction workers,

maintenance engineers,

staff and site users

ground gas (methane, carbon

dioxide) from organic wastes / buried

topsoil / natural peat deposits and

VOCs from soil and groundwater

sources, and radon gas from natural

ground

accumulation within buildings,

particularly underground voids,

confined spaces and service runs

to toxic (by inhalation) or

flammable/ explosive

concentrations, release of gas or

dust during disturbance caused

by development and inhalation


or natural sources unknown but their existence is

suspected; gas or vapour migration into commercial

premises within the development could cause long-

term health impacts or acute risks of injury/death

site investigation including gas

monitoring and groundwater

analysis to determine extent and

nature of any contamination and

migration pathways

2. humans –

Residents of nearby

dwellings



topsoil / natural peat deposits and

VOCs from soil and groundwater

sources

accumulation within buildings,

particularly underground voids,


to toxic (by inhalation) or

flammable/ explosive

concentrations



suspected; gas or vapour migration into inhabited

areas of the development could cause long-term

health impacts or acute risks of injury/death





migration pathways



topsoil / natural peat deposits

accumulation within voids,


to flammable/ explosive

concentrations



suspected; gas (methane) migration into commercial

premises within the development could cause

damage to property if fire or explosion result





migration pathways

3. property / services

pH, sulphate and organic

contaminants

Chemical attack of buried

concrete and plastic materials


or natural sources unknown but suspected






th September 2013

17

Receptor Source / Contaminant Pathway / Exposure Pollutant Linkage (in absence of mitigation) Further Investigation

Variable and weak soils in natural

and made ground, voids,

obstructions and relict structures

resulting in the potential for

compressible ground, differential

settlement, slope instability.

Movement of bearing strata

following construction and

damage to built development and

supporting infrastructure

Possible – Alluvium and made ground (particularly

waste deposits) may have resulted in unstable

conditions, previous development could have resulted

in various structures, voids and oversized materials.

4. vegetation / landscaping leachable metals / metalloids may be

present within soils

plant uptake Possible – extent, depth and nature of contamination

unknown; any contamination present at shallow

depths may pose a long term risk if present in

landscaped areas




5. ecosystems / protected

species & habitats –

badgers or other protected

species

An invasive species (Japanese

Knotweed) is present on the site

direct contact / food chain

digestion, colonisation of

sensitive habitats and

disturbance/destruction of habitat

Possible – An ecological assessment should be

carried out to confirm the extent of the Japanese

Knotweed and the presence of protected species

Removal/treatment of Japanese

Knotweed

6. surface waters – The

River Irwell

leachable metals / metalloids /


made ground, point sources may

also be present

migration via shallow

groundwater into local surface

water drainage network drainage

systems and River Irwell

Possible – any mobile contamination may enter

surface water drainage systems and adjacent River

Irwell through groundwater flow or preferential

pathways; discharge was noted from a culvert and a

surface flow.

site investigation including

groundwater analysis to determine

extent and nature of any

contamination

7. groundwater – Secondary

A Aquifer within superficial

alluvial deposits




also be present

migration via unsaturated zone Possible – vertical migration into alluvium is unlikely

to be significantly hindered. The majority of the site is

unsurfaced and therefore rainwater will infiltrate.




contamination

8. groundwater – Secondary

A Aquifer within bedrock




also be present

migration via unsaturated zone Possible – vertical migration via the overlying

alluvium is unlikely to be significantly hindered but

most groundwater movement is likely to provide

baseflow to the




contamination



th September 2013

18

6. Investigation Methodology

6.1. Objectives and Rationale

6.1.1. A number of both diffuse and localised potential contaminant sources have been identified.

The proposed use of most of the site for car parking associated with the planned cycle centre

is of low sensitivity, although the proposed commercial buildings can be regarded as

moderately sensitive to gas and vapour ingress. High sensitivity (residential) land use exists

in the surrounding area and the site is in proximity to a surface watercourse, compounded by

the likely presence of viable flow paths.

6.1.2. In order to provide the best likelihood of identifying ground contamination with the potential to

cause pollution or harm to human health a programme of intrusive investigations was

therefore designed to:

• confirm the ground conditions underlying the site;

• determine the presence, extent and nature of made ground and soil contamination;

• obtain information on the presence, depth and quality of groundwater;

• monitor ground gas concentrations and pressure/flow;

• determine the remedial requirements necessary to remove any pollution risks identified

and allow the proposed redevelopment to take place without risks to human health or the

wider environment;

• identify potential foundation conditions for the proposed development.

6.1.3. Due to the presence of various constraints including the presence of very dense vegetation

and soft ground in the southern parts of the site, several steep banks and “stand off” zones

around various live services and avoid potential disturbance of protected species, the actual

area available for investigation was about 2.1ha. A decision was made in consultation with

RBC to avoid penetrating the area of leather waste in case biological pathogens (anthrax) are

present.

6.1.4. The history of the site indicates the likelihood of significant heterogeneity within the ground;

alluvial soils are characteristically laterally and vertically variable and the multiple phases of

tipping, reworking and development are likely to have resulted in highly localised features. In

the parts of the site where localised features of interest were identified, and which could be

accessed using the plant and resources available, a targeted approach was adopted with trial

pit entries located within the historical waste bodies and previously developed parts of the site.

6.1.5. For the remaining areas a systematic (non-targeted) "stage 1" investigation of the area was

proposed be carried out to ensure conditions over the maximum possible area of the site were

described. A square grid was adopted in order to facilitate the setting out of positions over the



th September 2013

19

large site; however sampling locations within each square were irregular. In practice, given

the constraints described, a nominal 30m grid spacing of entries was achieved in the

accessible parts of the site.

6.1.6. Sample collection was designed to both include any soils where contamination indicators were

identified and obtain representative sets of the various principal soil types of made ground

present.

6.1.7. Borehole entries were also targeted to intercept likely migration pathways for gas and

groundwater movement from the potential sources identified towards existing or future

receptors including around the perimeter of the reported leather waste, within the former

channel of the River Irwell, beneath the proposed building locations and along the northern

Plot 4 site boundary where it runs parallel to the current path of the river and where migration

into the watercourse would be most likely. In order to allow the maximum possibility of

detecting significant migration of dissolved phase contaminants the response zones of the

installations were not targeted to specific horizons and occupy almost the full depth of each

borehole.

6.1.8. Water samples from the two discharges to the river ( a culver crossing Plot 4 and a surface

watercourse running parallel with, and near to, the western boundary) from the direction of the

potential source zones identified were also deemed necessary in case contaminant migration

via such preferential flow paths was occurring.

6.2. Fieldwork

6.2.1. The site investigation utilised trial pits and boreholes to permit visual inspection and logging of

shallow strata, to obtain samples from the made ground and shallow natural strata and to

install ground gas and groundwater monitoring installations. Trial pit and borehole locations

are shown on drawing 007.

6.2.2. Apart from access by plant and personnel, the main constraint to investigation was found to be

the presence of numerous below-ground obstructions. Although additional equipment was

brought onto site to break through these, a number of entries, mainly those targeted by

borehole entries, could not be continued to the planned depths.

6.2.3. The investigation was undertaken between the 8th and 10

th May 2013 the supervision of SGP

Geo-Environmental Consultant B Harvey. For the purposes of geotechnical assessment a

selection of trial pits were inspected by Geoventures Geotechnical Engineer, Dr J Crook.



th September 2013

20

6.2.4. Works involved:

•••• excavation of 27 trial pits (TP01–TP27) by wheeled excavator (JCB) to a maximum depth

of 4.0 m bgl;

•••• drilling of 11 boreholes (BH1-BH11) using a shell and auger rig to a maximum depth of

11m;

•••• screening of all soil arisings with a PID for volatiles, inspection and logging of ground

conditions;

•••• SPT testing in selected shell and auger boreholes at 1m intervals in upper 5m thereafter

at 1.5m intervals;

•••• collection of 19 soil samples for a range of laboratory analyses detailed in Table 6.1;

•••• collection of 8 groundwater samples from new boreholes and two samples from previous

boreholes for a range of in-situ testing and laboratory analyses detailed in Table 6.2;

•••• collection of 3 surface water samples.

6.2.5. Gas and groundwater monitoring wells were installed in all within borehole entries; details of

installations are included in Appendix B. In all cases, the upper 1.0m of the wells were sealed,

with response zones installed through the remaining depth of the boreholes, i.e. not restricted

to specific horizons (as the groundwater investigation was designed to screen the site for

significant contamination and pollution sources).

6.3. Chemical Analysis

6.3.1. Chemical analysis of soils and waters was carried out by Jones Environmental Laboratories,

Deeside, respectively working where possible to MCERTS and / or ISO 17025 accreditation.

Samples were stored in appropriate containers as advised by the laboratory, placed in a cool

box, and delivered to the laboratory within 24 hours. Chain of custody documentation was

completed and is retained by SGP.

6.3.2. Nearly all of the soil samples collected were of made ground, as most exposure is likely to

occur at shallow depths, most contamination likely to arise on the site is likely to be a result of

deposition of wastes and the potential for mobilisation of contaminants from made ground is

assessed through the groundwater monitoring programme.

6.3.3. Either a suite of chemical analysis of common industrial contaminants considered likely to be

relatively widespread on the site (comprising pH, soil organic matter, asbestos screen, pH,

metals / metalloids, PAHs, asbestos screen, hydrocarbons), or pH and soluble sulphate,

referred to as BRE suite was selected. The soils analysis schedule is set out in the following

table:



th September 2013

21

Table 6.1: Summary of Soil Chemical Analysis

Strata description sample ref depth (m bgl) analytical

suite

made ground – cohesive

Black fibrous clay with occasional gravel of metal and fabric

TP14 ES1 TP24

3.5 0.8

Full Suite

Made ground- granular (sand)

Black sand and gravel of brick and concrete

TP2 ES1, TP13 ES2, TP22 ES1 TP6

2.6 0.5 0.1 0.3

Full Suite

Made ground – granular (ash/clinker)

Red brown/grey ashy sand with gravel of wood, glass and metal in places

TP8 ES1, TP11 ES1,

2.1 1.5

Full Suite

Made ground – silt

Grey silt/ silty sand TP12 ES1, TP13 ES1

0.8 0.3

Full Suite

Made ground- granular (rubble)

Sand and gravel varyingly of metal, brick, concrete, fabric, sandstone, slate and clinker

TP7 ES1, TP10 ES1, TP10 ES2, TP22 ES1 TP19, TP20 TP23

0.4 0.2 3.1 0.1 0.5 0.6 0.5

Full Suite

Made Ground- topsoil

topsoil TP24 0.2 Full Suite

natural soils - silt Black organic silt TP1 ES1 2.9 Full Suite

6.3.4. Water sampling was carried from selected boreholes out on 4th June 2013. Two discharges to

the River Irwell near the northern (Plot 4) site boundary (a surface water flow and culvert) were

also sampled during the water monitoring exercise.

6.3.5. Groundwater was recovered using a peristaltic pump, supplemented by bailers. In-situ

monitoring was carried out using a YSI Professional Plus Series Water Meter; the parameters

tested were pH, dissolved oxygen, temperature, conductivity and redox. Wells were purged

until steady state redox conditions were achieved before samples were collected using the

preservation methods described previously.

6.3.6. All water samples were submitted for chemical analysis for hydrocarbons and 54 target VOCs,

considered the most common organic pollutants likely to be associated with discharges from

waste bodies. Assessment for these substances was carried out in groundwater rather than

soils as these substances are more likely to be detected in dissolved phase (given the greater

heterogeneity of the medium) if significant contamination is present on the site. A selected

number of samples (BH9, BH10, BH11 and OLD BH2) were subjected to a larger suite

specified to include contaminants which may be associated leachate generated by the leather

wastes reported. The locations targeted for this larger suite of analysis were all located in

close proximity to the leather waste area, the selected analysis schedule is summarised in the

table below:



th September 2013

22

Table 6.2: Summary of Groundwater Chemical Analysis

Borehole Response zone (m

bgl)

In-situ testing analytical suite

BH2,

2.0-2.5 MG 2.5-10.45 silt and sand

BH3,

1.0-3.0 MG 3.0- 10.45 silt and gravels

BH5,

1.0-1.5 MG 1.5- 10.0clay and silt

BH6,

1.0-2.0 MG 2.0-6.0 gravel

BH7,

1.0-5.2 MG 5.2-10 clay

OLD BH1 unknown

Dissolved oxygen, redox, conductivity, pH, & temperature

VOCs, EPH

BH9 (c),

1.0-9.5 MG 9.5-11.0 sand and gravel

BH10, 1.0-11.0 MG

BH11, 1.0-10.5 MG 10.5-11.0 gravel

OLD BH2 unknown

Dissolved oxygen, redox, conductivity, pH, & temperature

Boron, chromium, VOCs, SVOCs, pesticides, EPH, sulphate, ammonical nitrogen, hexavalent chromium, sulphide and pH

Upstream, OF1, OF2

n/a Dissolved oxygen, redox, conductivity, pH, & temperature

VOCs, EPH

6.3.7. Ground gas monitoring in each of the installations was carried out by SGP staff using a

calibrated GFM 430 gas analyser and comprised three week programme which included two

monitoring rounds when atmospheric pressure was less than 1000mb, and was falling.



th September 2013

23

7. Investigation Observations

7.1. Physical Observation

7.1.1. The trial pit and borehole logs are presented in Appendix B. For the purposes of description,

the site has been divided into the various Plot areas.

7.2. Plot 1

7.2.1. Trial pits TP24-TP26 were located within this Plot 1 (the former Lee mill to the north of the

River Irwell. The ground conditions comprised 0.4m bgl of topsoil on the southern side of the

plot, underlain by made ground comprising clay to 1.7m bgl and ashy sand to 3.1m bgl.

Natural ground comprised gravels. The northern and eastern parts of the plot comprised

made ground of clayey sand and gravel to a minimum of 1.0m bgl overlying made ground clay

in the east and sand and boulders in the north (including remains of a wall). Natural siltstone

was encountered at between 2.2-3.1m bgl.

7.3. Plot 3

7.3.1. Trial pits TP18-TP20 were located to the west of the existing access road. The hardstanding

was found to be extensive, with a thin build up of soil having accumulated across concreted

areas. In the centre of the site 0.5m bgl of made ground was encountered comprising sand

and gravel with concrete, bricks and metal present. The trial pit was terminated on concrete.

In the northern half of the plot 1.5m bgl of made ground was encountered comprising sand,

cobbles and boulders of sandstone, and brick overlying natural silt present to 3.8m bgl.

7.4. Plot 4

7.4.1. Trial pits TP1-TP10 and TP22-23 as well as boreholes BH1-BH7 were located to the east of

the site access road, with trial pits TP1 & TP2 and BH1, BH1a & BH2 targeted within the

footprint of the southern most proposed building and TP22 & TP23 and BH3 & BH4 targeted

within the footprint of the northern proposed building.

7.4.2. The southern building location was underlain by made ground comprising sand, gravel and

concrete to between 2.5-3.7m bgl, underlain by soft natural black organic silt to 4m over

medium dense sand and gravel to at least 10.45m bgl. A concrete obstruction prevented

drilling of BH1 at 0.6m bgl necessitating the additional entry BH1A, which penetrated a similar

thickness of made ground over 0.7m of firm silt before reaching medium dense sand and

gravel at 3.2m bgl.

7.4.3. The northern building location was underlain by made ground comprising sand and gravel of

concrete to between 1.1m and 3.0m bgl. Natural ground was not encountered on the trial pit

on the eastern side of the proposed building due to groundwater ingress. Soft silts were also



th September 2013

24

present beneath the made ground in the southern borehole entry; in the northern borehole

mage ground to 3.0m bgl was underlain directly by dense sand and gravel to 10.45m bgl.

7.4.4. The remainder of Plot 4 comprised made ground comprising sands, ash and clinker, gravels

and concrete (generally friable, but occasionally strong and including rebar) to depths between

0.3-5.2m bgl. Significant thicknesses (>1.2m) of made ground were encountered within all

locations with the exception of TP5. The excavations located in the vicinity of the former

batching plant (TP6-TP9, BH6-BH7) encountered at least 2.0m bgl of made ground, (5.2m bgl

in BH7). Made ground was underlain by natural sand, silt and clay, with rounded gravel

encountered at depth (3.3m bgl) within TP3. Stiff clays were encountered below 6.0m bgl in

BH5 and BH7.

7.5. Plot 5

7.5.1. Trial pits TP11-TP14 and borehole BH9c were targeted within the approximate extent of the

historical tip area; trial pits TP15-TP17 were located in the western part of Plot 5. Boreholes

BH9-9b, BH10-BH11 were targeted to the area conjecture to surround the leather waste area.

The possible land filled area encountered made ground comprising ashy sand with frequent

glass and metal within TP11-TP13 to a depth of at least 4.0m bgl in TP11 and to 9.5m bgl in

BH9c. TP12 encountered differing types of made ground along the length of the trial pit, with

grey cement bound sand, in the eastern half of the pit to a depth of 1.8m bgl, underlain by

natural sand. TP14 encountered similar material to a depth of 3.0m bgl, underlain by made

ground clay with metal and fabric to a depth of at least 4.0m bgl. BH9c encountered natural

ground comprising sand/gravel from 9.5-11.0m bgl.

7.5.2. The western half of Plot 5 comprised made ground of sand and weakly cemented sand and

gravel to depth varying between 1.7-4.0m bgl, natural ground was not encountered and TP15

and TP16 were both terminated on concrete.

7.5.3. The easternmost boreholes targeting the surrounds to the leather waste material encountered

leather waste (BH9a, BH9b) at between 2.7-3.0m bgl and were terminated on contact. BH10

and BH11 encountered made ground ash and cinder fill to depths varying between 10.2-

10.5m bgl, underlain by natural gravel.

7.6. General Stratigraphy

7.6.1. A meander of the former channel of the River Irwell passed through the central part of the site

crossing Plots 3, 4 and 5. The entries which may intercept the former channel are: TP23, TP2,

BH2, BH3 and TP10. The presence of the organic silts described above is likely to originate

from the channel which appears to have been allowed to silt up in the northern parts of the

site.



th September 2013

25

7.6.2. Widespread made ground was encountered across the site, consisting largely of reworked

natural soils with varying amounts of brick, concrete and ash or clinker, as well as deposits

containing largely ash and clinker and various, generally inert, waste deposits. Across the

western half of Plot 5 and majority of Plots 3 and 4 this comprised concrete/weakly cemented

sand and gravel. Within the eastern half of plot 5 this comprised ashy sand with glass and

metal, consistent with landfill material. The greatest depths of made ground (up to 10.2m bgl)

were encountered in Plot 5 in the south of the site and correspond to areas where levels

appear to have been raised through historical tipping; the materials present in this area are

dominated by ash and clinker.

7.6.3. Alluvium comprising variously soft clays and silt, and sand and gravels with a high organic

content appears to be present under all parts of the site, where made ground could be

penetrated with the exception of Plot 1 which went straight onto siltstone. Underlying course

granular deposits and generally stiff, silty clay may represent earlier glacial deposits. Bedrock

comprising siltstone was only encountered in Plot 1 (trial pits TP25 and TP26).

7.6.4. The encountered ground conditions are generally consistent with the mapped geology of

alluvium over lying sandstone (encountered as siltstone), and the history of the site with the

infilling of the former River Irwell channel, widespread tipping of deposition of boiler ash/clinker

and discreet deposits of demolition waste and other refuse.

7.7. Groundwater

7.7.1. Groundwater was encountered locally during both drilling and trail pitting. During trial pitting,

within Plot 1 groundwater was encountered at 3.2m bgl, within Plot 3 no groundwater was

encountered, within Plot 4: 2.4-3.6m bgl and within Plot 5:1.7-2.1m bgl (eastern area only).

The flows encountered in plot 5 are probably perched water, in Plots 4 and 1 strikes were

consistent with the nearby river level so these are flows likely to be in hydraulic connectivity

with the river.

7.7.2. Groundwater in the borehole entries was encountered in made ground strata at 8.5m bgl

(BH10 and BH11) at 9.5m bgl in BH9c and within natural strata in BH 2 at 4.0m bgl, BH3 at

4.0m bgl, BH6 at 5.1m bgl. All groundwater strikes within boreholes were described as

seepages. None of the strikes rose in the wells over a period of about 20 minutes indicating

that the groundwater present in these materials is not confined.

7.7.3. Water levels in the installations were monitored as part of the ground gas assessment, the

results of which are discussed in Section 8.3 below. The dips of the wells recorded over the

gas monitoring programme is summarised below:



th September 2013

26

Table 7.1: Summary of Groundwater Chemical Analysis

Well number Depth to water (range) m bgl

BH1 2.23-2.32

BH2 2.21-2.24

BH3 2.18-2.23

BH4 3.23-3.27

BH5 3.58-3.6

BH6 3.39-3.4

BH7 3.84-3.9

BH9 8.25-8.34

BH10 7.3-7.43

BH11 6.86-7.02

OLD BH1 3.05

OLD BH2 7.17

7.7.4. A detailed topographical survey has not been undertaken; it is not possible to compare

groundwater levels to a datum without such a survey. However, general assumptions with

regard to water levels can be made. Groundwater levels within Plot 4 generally appear to

correlate with river levels and therefore groundwater can be assumed to be in hydraulic

continuity with the river and flowing generally towards it. Within Plot 5 ground waters are likely

to reflect the general valley profile and flow is likely to have a more westerly direction although

this is not proven.

7.8. Contamination Indicators

7.8.1. Organic odours were noted during the site investigation within natural black organic silt/clay in

TP1 (2.8-3.5m bgl), TP3 (2.0-3.3m bgl), TP5 (1.3-1.7m bgl), TP13 (2.0m bgl), TP14 (3.0-4.0m

bgl) and made ground sand at TP11 (2.0-2.5m bgl) and TP14 (0.2-0.8m bgl), these are not

necessarily indicative of contamination but are characteristic of soils with a high organic

content with subsequent implications for gas generation and stability.

7.8.2. Wood was encountered within boreholes BH2 0.0-0.6m bgl, BH9a 0.9-1.6m bgl and BH9 0.8-

1.0m bgl described as soil and wood fill (approximately 10% organic matter). Wood was also

encountered within trial pits TP11 0.5-4.0m bgl, TP13 0.35-2.7m bgl, TP14 0.2-0.8m bgl, TP25

0.0-1.3m bgl and TP260.0-1.0m bgl described as occasional cobbles of wood.

7.8.3. Ash and clinker were encountered within the majority of locations in the eastern half of Plot 5,

as well as BH7 2.0-4.5m bgl, BH10 1.0-10.2m bgl, BH11 0.25-10.5m bgl, BH9a 1.6-2.7m bgl,

BH9b 2.0-3.0m bgl and BH9c 5.0-9.5m bgl.



th September 2013

27

7.8.4. Black leather waste was encountered in BH9a and BH9b at 2.7m bgl and 3.0m bgl

respectively, this was not sampled and the borehole was terminated on encountering leather

with the affected arisings replaced at the depths encountered.

7.8.5. Hydrocarbon odours within made ground in TP2 (2.1-3.7m bgl) and a strong diesel odour in

made ground in TP6 (0.3-2.5m bgl decreasing with depth) were noted. PID screening of

representative samples of the strata produced results that were consistently below the

minimum limit of detection of the instrument (0.1 ppm).

7.8.6. No materials which can particularly be suspected of containing asbestos fibre (cement

sheeting, insulation/lagging, gaskets or brake components), or visible fibres were described.

7.8.7. No hydrocarbon odours, floating product or other visual or olfactory indicators of contamination

have been noted in groundwater during the investigation or monitoring.



th September 2013

28

8. Investigation Results

8.1. Results of Soil Analysis

8.1.1. The results of the soil analyses are compared to human health critical values (CVs) for initial

screening purposes. The CVs adopted are appropriate to the environmental setting and

proposed future commercial use of the site, and are taken primarily from CLEA Soil Guideline

Values (SGVs) published by the Environment Agency and the LQM / CIEH Generic

Assessment Criteria (GACs). These criteria are generally derived using the CLEA v1.04 or

1.06 model under a standard default commercial land-use scenario (This scenario considers a

16-65 year old female who visits the site regularly to work so is probably sufficiently

conservative to protect for the other human receptor considered, a visitor to the planned

centre). The SGV for lead has been withdrawn by the EA, previously DEFRA proposed a

substantial rise in the SGV in its "Way Forward" document. In view of the uncertainty with

respect to a future lead SGV, continued use is made of the previous value in this assessment.

8.1.2. Where published human health critical values are unavailable or inappropriate (because the

substances does not significantly affect human health but might have an effect on other

receptors), then other commonly-used screening values are used.

8.1.3. The made ground samples were initially screened to establish whether any contaminants

exceeded screening criteria. These are identified below. Only determinants in exceedance of

screening criteria are listed below, all other determinants are detailed within laboratory data

presented within Appendix C.

Table 8.1: Summary of Soil Exceedances

Contaminant Number of

Samples

Range of Concentrations

(mg/kg or indicated)

Soil standard adopted and

concentration (mg/kg or indicated)

Exceedances

Lead 10 14-1931 750 (withdrawn

SGV) TP13 ES2 0.5m

Copper 10 22-980 200 (DEFRA plant) TP13 ES2 0.5m, TP14 ES1 3.5m

Zinc 10 72-3340 300 (DEFRA plant) TP13 ES2 0.5m, TP14 ES1 3.5m

Chrysotile

TP13 ES1 0.3m, TP11 ES1 1.5m, TP2 ES1 2.6m,

TP10 ES1 0.2m, TP10 ES2 3.1m

TP6 0.3m TP23 (noted on lab

data as TP2S) 0.5m

TP24 0.2m

Asbestos 19 Presence

Amosite TP11 ES1 1.5m



th September 2013

29

Notes to table: CLEA SGV: Soil guideline value published by DEFRA/EA, ‘commercial scenario (adjusted for 6% SOM);

sandy loam soil LQM / CIEH: Generic assessment criteria published by Chartered Institute of Environmental Health and Land

Quality Management Ltd, residential land use scenario; 2nd

Edition (at 6% SOM) DEFRA plant Threshold guideline for the protection of sensitive plant species used by MAFF 1: CV exceeds of solubility saturation limit provided in (), i.e. possibility of free product at this level

8.1.4. The presence of asbestos fibres has been identified in the made ground on the site in a

number of samples, including several from shallow depths. Due to the presence of asbestos

fibre in samples, dry analysis could not be undertaken by the laboratory due to health and

safety considerations, therefore metal analysis has only been undertaken on ten out of

nineteen samples. Elevated concentrations of lead, copper, zinc, hydrocarbons were detected

associated with the landfilled area within Plot 5, however only lead exceeded criteria for

commercial/industrial landuse.

8.1.5. Although not considered a contaminant with the potential to impact human health through

direct exposure, the degradable organic content of the made ground has implications for its

potential to generate ground gas. Measurements of total organic content (soil organic matter)

were made in all the samples of made ground submitted – and varied between 0.5 in TP12 at

0.8m within made ground sand to 16.9% in TP14 at 3.5m bgl in made ground, clay. The

average total organic content (TOC) within made ground was 5.9%. The highest TOC of

49.7% was encountered was within TP8 at 2.1m within ashy sand directly over natural organic

silt.

8.1.6. The results of the soil testing are also compared to the threshold values provided by United

Utilities (UU) for places where water supply pipes are to be laid. The following exceedances

of the threshold values within the soils on site are noted:

Table 8.3: Summary of Exceedances of UU Threshold Values

determinant threshold

(mg/kg)

exceedances

EC10-EC16 aliphatic and aromatic hydrocarbons

10 TP14 ES1 3.5m (771.1mg/kg), TP11 ES1 1.5m (57.4mg/kg), TP1 ES1 2.9m (17.4mg/kg), TP13 ES2 0.5m (25.8mg/kg), TP12 ES1 0.8m (26.1mg/kg)

EC16-EC40 aliphatic and aromatic hydrocarbons

500 TP14 ES1 3.5m (74761mg/kg), TP13 ES2 0.5m (12049mg/kg), TP11 ES1 1.5m (14827mg/kg) TP6 0.5m (389mg/kg)

Notes to table: Other substances listed by UU as potential contaminants of concern with respect to tainting/toxification of drinking water supplies are either considered unlikely to be present on the site or are screened for as part of the groundwater monitoring programme to indicate the presence of significant sources



th September 2013

30

8.1.7. The results of the soil testing are also compared to the threshold values provided by United

Utilities (UU) for places where water supply pipes are to be laid. Several exceedances for

hydrocarbons were detected.

8.1.8. Laboratory tests for pH/Sulphate were targeted to the natural superficial deposits beneath the

proposed building locations as these are considered the most likely to come into contact with

poured in-situ concrete, however a small number of samples of made ground local to this area

were also subject to the test.

Table 8.3: Summary of Exceedances of UU Threshold Values

determinant Range of values

(mg/l for SO4/

units for pH)

Characteristic value

(mg/l for SO4/ units

for pH) #

Classification*

Water Soluble Sulphate (2:1 leach test)

<10-61 61 DS-1

pH 8.2-8.3 8.2 AC1 Notes to table: Classification carried out in accordance with BRE SD1 #: Characteristic value determined from small sample set (maximum recorded value BRE SD1) *: Classification based on Brownfield site not likely to contain pyrite

8.1.9. These indicate a classification of DS-1, AC1 in accordance with current BRE guidance. Two

made ground samples from beneath the proposed building locations contained a maximum

sulphate of 389mg/l and a pH of 8.3, also within the classification of DS-1, AC1. However,

made ground is inherently variable and samples from this suggest a classification of AC2 may

be appropriate due to the variability of sulphate across the site, and it is recommended that

this more severe case is adopted for buried concrete for the proposed structures as a

precautionary measure.

8.2. Results of Groundwater Analysis

8.2.1. Ten groundwater samples were collected from the monitoring installations in BH2, BH3, BH5,

BH6, BH7, BH9, BH10, OLD BH1, OLD BH2.

8.2.2. In situ testing of groundwater was carried out to establish some of the general parameters;

these are detailed in the table below.



th September 2013

31

8.2.3. Groundwaters were analysed for VOCs and EPH, samples taken from the vicinity of the

leather waste (BH9, BH10, BH11, OLDBH2) were also analysed for SVOCs, phthalates,

pesticides, sulphate, ammonical nitrogen, chromium (III&VI), pH, boron and PAHs. The

locations of the boreholes are indicated in Drawing 007.

8.2.4. No determinants were detected in excess of EQS screening criteria. No VOCs, SVOCs,

phenols, PAHs, phthalates or pesticides were detected above level of detection with the

exception of boron, chromium, sulphate, ammonical nitrogen and pH; however these

concentrations remain below the screening criteria.

8.3. Results of Surface water Analysis

8.3.1. Three surface water samples were collected from the River Irwell identified as UPSTREAM,

OF1 and OF2. OF 1 and OF2 were identified outfalls into the River Irwell. The locations of

surface water sampling are indicated in Drawing 007. These were analysed for VOCs and

EPH.

8.3.2. No determinants were detected in excess of EQS screening criteria. No VOCs or EPH were

detected above level of detection.

8.4. Results of Ground Gas Monitoring

8.4.1. In accordance with current best practice, as set out in “The Local Authority Guide to Ground

Gas” and “The Ground Gas Handbook”, limiting borehole flows of hazardous ground gas

obtained during the monitoring programme are compared to published Gas Screening Values

(GSV) to inform design of an appropriate level of gas protection for future development.

8.4.2. Concentrations and flows of gas are combined to produce a GSV which is then compared to

widely accepted threshold values published by CIRIA; these are summarised in the table

In Situ Measured Parameters

conductivity

Location

Temperature (◦c) Dissolved

Oxygen (mg/l) spc e

pH Redox potential

BH2 13.4 13.4 30.5 23.2 7.14 222.7

BH3 9.8 12.6 6.6 4.9 7.49 202.9

BH5 8.1 18.1 4.8 3.5 7.24 175.6

BH6 10.6 12.33 6.6 4.8 7.00 148.9

BH7 14.4 9.9 8.2 6.6 7.31 127.6

BH9 9.3 13.23 21.4 14.6 7.16 120.3

BH10 10.4 12.68 7.9 5.7 7.47 7.2

BH11 9.7 1.73 6.8 4.6 6.84 -28.7

OLD BH1 7.8 2.7 33.0 22.0 6.77 -61.9

OLD BH2 10.4 13.04 62.7 45.1 6.99 14.8



th September 2013

32

below. Maximum total concentrations are also taken into account. Coloured cells indicate the

relevant “Characteristic Situation” for each monitoring installation and the worst case

(maximum concentration x maximum flow) for the whole site. Where readings are below the

limit of detection, concentrations or flows are assumed to be at the limit of detection to

generate GSV to ensure a conservative approach to screening, however only steady borehole

flows are used.

Table 8.5: Summary of 2012 Ground Gas Results

Well No. visits Max CH4

(%)

Max CO2

(%)

Max

Flow*

(l/hr)

CH4

GSV

(l/hr)

CO2

GSV

(l/hr)

CIRIA

BH1 3 0 0.5 -0.2# - 0 0 0.001 CS1

BH2 3 0 1 0 0 0 CS1

BH3 3 0 0.3 -0.3# -0 0 0.0009 CS1

BH4 3 0 4.2 0 0 0 CS1

BH5 3 0 3.3 0 0 0 CS1

BH6 3 0 3.1 0 0 0 CS1

BH7 3 0 3.0 0 0 0 CS1

BH9 3 0 6.2 0 0 0 CS1

BH10 3 0 5.9 -0.2# -0 0 0.012 CS1

BH11 3 0 6.6 0 0 0 CS1

Site^ 3 0 6.6 -0.2

# 0 0.013 CS1

Notes to table: * Steady flow (after 30 seconds)

# negative flows converted to positive as a worst case scenario

^ site classification is based on highest recorded flows and highest recorded concentrations from the full monitoring

dataset

8.4.3. Based on the available monitoring date the site would be assessed under the CIRIA

classification scheme as characteristic situation 1 with respect to methane and carbon dioxide.

8.4.4. No hydrogen sulphide or carbon monoxide was detected during the monitoring programme.



th September 2013

33

8.4.5. Geotechnical Assessment

8.5. Development Proposals

8.6. SGP understand that the proposed development plans for the site comprise hardcore

compacted car parking across the majority of Plots 3, 4 and 5, a cycle track area within Plot 1

and on the southern and eastern side of Plot 3, two light steel framed two storey buildings for

use in the cycling centre as welfare facilities and retail units. These are understood to impose

relatively low floorslab loadings at, or close, to existing ground level.

8.7. SGP understand the planned car parking will be unsurfaced; other infrastructure will include

metalled access roads, new utility corridors and areas of landscaping. Plot 1 may be

reprofiled to form a cycle track.

8.8. A full geotechnical assessment has been undertaken by Dr John Crook of Geoventures (UK)

Ltd on behalf of SGP, this is included in full within Appendix E and is summarised below.

8.9. Ground Conditions

8.10. The majority of the site is underlain by made ground comprising broken concrete, sand, gravel

and clay typically varying from loose to dense in relative density or soft to firm in consistency,

extending to between 2.5m and 3.5m depth. Numerous obstructions and/or oversized

materials are present as surface deposits and within the made ground.

8.11. Within BH1 – BH3, in the locality of the proposed buildings, made ground was underlain by a

stratum of soft clay/silt typically around 1.0m thick. This which probably represents the infilled

River Irwell material which rests on top of the underling glacial soils.

8.11.1. The glacial deposits comprised mainly granular materials, with mixtures of sand and

gravel, generally medium dense in relative density and claybound in parts with subordinate

layers of firm and firm / stiff clays and silts.

8.11.2. The underlying rock units are shown on BGS mapping as the Lower Haslingden Flags

(sandstone), no faulting is indicated on the site. The sandstone bedrock was not encountered,

however trial pits TP25 and TP26 within Plot 1, encountered siltstone at between 2.2 and 3.1m

bgl. This was interpretated as bedrock.

8.11.3. There are low or very low natural hazards associated with collapsible ground. The site is not

affected by brine pumping, coal mining or other mineral extraction activities. Risks from

shrinking/swelling clays and running sand have been assessed as low. No peat was

encountered in the investigation and therefore widespread compressible natural soils appear



th September 2013

34

to be absent but the presence of localised pockets of peat within the alluvium cannot be

discounted.

8.11.4. Slope stability issues may affect the southern boundary of the site and the boundary between

plots 4 and 5 and the southern parts of Plot 3. These are associated with the steep drop down

from the higher ground to the south of the site which was tipped early in the site’s

development history; more recent waste deposits appear to consist of variable, albeit generally

inert, materials which have been loose tipped and not subject to methodical compaction or

consolidation. The area of leather waste may be assumed to contain a significant volume of

degradable organic matter which could undergo future settlement.

8.11.5. The slopes appear to be well vegetated and stable, and ash banks may typically remain stable

at a relatively steep angle of repose; however a detailed slope stability assessment was

outside the scope of the investigation and the summary of previous assessments provided

contain reference to a recommendation that the large bank at the southern end of the site may

require some re-profiling to improve its stability.

8.11.6. In addition, retailing walls are present on all sides of Plot 1, both in relation to the lower River

Irwell running alongside the site, and higher ground to the north and east containing

roadways. Outside the site at a distance of 15m north of Plot 3, substantial areas of collapse

and slumping of the southern bank of the River Irwell is apparent.

8.12. Foundation Options

8.13. The variability of the fills and weak nature of much of the natural alluvium represents

significant problems in the choice of appropriate foundations. The available information can

only give a preliminary view, and more investigation will be required to facilitate a more

detailed appraisal. However, in general terms, on the assumption of two simple steel framed

two storey buildings with a relatively low imposed floorslab loading, at or close to existing

ground level, the following comments are applicable.

8.14. Shallow footings would be founded on variable made ground materials resulting in a probable

gross variation in allowable bearing capacity and compressibility properties. This would result

in a high risk of differential settlement. This is not considered to be a viable option.

8.15. To avoid the problems identified above deep footings would need to go to sufficient depth

beneath both the made ground and underlying soft clay / silt to bear directly on the competent

glacial soils; with necessary depths of up to around 3.0m – 3.5m below existing ground level

and resultant problems of trench stability and groundwater control this is not considered to be

a viable option.



th September 2013

35

8.16. Vibroflotation or Piling would appear suitable to either improve the overall properties of the

made ground or transfer loads to the deeper competent soils beneath the made ground and

soft alluvium, however, both could be adversely affected by obstructions in the made ground

and expensive for the type of structures envisaged.

8.17. Both true (flat bottomed) rafts, or pseudo rafts (which are essentially reinforced slabs with a

shallow edge thickening to a width to reduce bearing pressures as appropriate), are commonly

used where the near surface soils are variable both in terms of type and thickness to

significantly reduce the overall ground bearing pressures and hence reduce the risk of

differential movements. However, even reduced overall pressures could result in some

settlement of the underlying soft clay / silt although this may be tolerated depending on the

ability of the proposed structures to accept differential movement.

8.18. On the assumption of only lightly loaded slabs, if the formation is subjected to heavy proof

rolling with suitable treatment of any soft spots revealed then ground bearing floorslabs could

be used although there would still remain some risk of long term potentially differential

movement.

8.19. Groundwater and Excavations

8.19.1. Groundwater is present within the fluvioglacial deposits generally below 2.5m bgl, however

artesian conditions have not been encountered on the site. The depth to the water table

should preclude the requirement for dewatering in most of the site, which appears free-

draining. Perched water may be present locally over the alluvium.

8.19.2. With the exception of the entries located in Plot 1 within the loose gravels, most trial pit walls

were stable until substantial waters were encountered; it is not anticipated that deep

excavations would be required in this area given the planned use as a cycle track.

8.20. Infrastructure

8.20.1. Where free-draining granular deposits are present then CBR values of >15% should be

achievable for pavement design following removal of foundations and other obstructions, re-

grading and proof-rolling of the formation. Alluvial soils comprising clays and silts should be

assumed to have CBR values of <2% and are likely to be frost-susceptible.

8.20.2. The previous comments regarding potential for compressibility and settlement of the alluvial

soils will apply particularly where a significant increase in levels and loading of the weak soils

is envisaged. Confirmation of proposed development levels is not currently available and the

impact any future regarding must be considered by the designers of the infrastructure required

to support the development as well as the proposed buildings.



th September 2013

36

9. Conceptual Model and Risk Assessment

9.1. Methodology

9.1.1. Information from the site investigation has been used to refine the likely source-pathway-target

relationships identified in the preliminary Conceptual Site Model (CSM). Tier 1 quantitative

risk assessment has been undertaken by comparison of contaminant concentrations in various

media (soil, groundwater and ground gas) to generic screening criteria. These are values

appropriate to the intended commercial end-use of the site, and indicate whether potentially

unacceptable risks to receptors are likely to exist, requiring either more detailed site-specific

risk assessment or remediation to break the potential contaminant linkage.

9.2. Source Assessment

9.2.1. The historical mapping indicates the site to have been subject to infilling at various times

between the diversion of the River Irwell at the end of the 19th Century and tipping of material

from the southern boundary of the site ongoing from pre 1893, as well as the landfilled area

within Plot 5 dating from 1962-1987. Recent, possibly uncontrolled, tipping of waste materials

is also apparent on site. In addition, a concrete batching plant and stone cutting works were

present within Plots 3 and 4, and a mill within Plot 1. Low levels of solid (or adsorbed)

contaminants, specifically heavy metals, PAHs and asbestos fibre may be anticipated in all

parts of the site and one significant exceedance of criteria for commercial/industrial landuse

for lead was recorded in the eastern tip area.

9.2.2. Light hydrocarbons with the potential to mobilise through vapour or dissolved phase were not

encountered, although diesel/lubricant range hydrocarbons below screening criteria were

detected in a number of samples from the eastern tip. The vicinity of TP6 contained olfactory

evidence during the site investigation as a likely hydrocarbon hotspot, however hydrocarbons

detected within the sampled material did not exceed human health screening criteria. If the

hydrocarbons are associated with a residual reservoir such as an underground fuel tank, this

could represent a significant source with the potential for future release.

9.2.3. The leather wastes present are considered constitute degradable organic matter and the

potential for biological contamination (anthrax spores) cannot be discounted, however

groundwater monitoring in the immediate vicinity does not indicate the presence of soluble

hazardous gasses, organic contaminants or that polluting leachate is being generated.

9.2.4. Other soils have a limited potential to generate hazardous ground gases and monitoring

indicates low concentrations of carbon dioxide with methane absent. No VOCs have been

detected in the groundwater on the site or through soil screening carried out. The site is in an

area where radon protection measures may be required.



th September 2013

37

9.3. Potential Targets

9.3.1. The principal vulnerable receptors, assuming commercial development of the site, will be:

• The construction workforce;

• future site users/staff;

• on-site building structures and infrastructure (cycling centre; carparking; roadways;

services);

• soft landscaping areas;

• neighbouring residential properties;

• shallow groundwater acting as a intermediate receptor/pathway to the nearby River Irwell.

9.4. Human Health Assessment

9.4.1. None of the contaminants identified were recorded at concentrations that would be expected

to pose an acute risk to human health during site preparatory and construction works provided

normal occupational hygiene measures and safe working practices are adhered to and

adequate environmental controls are implemented in any future development scheme.

9.4.2. The presence of relatively widespread traces of asbestos fibre within the soils has been

identified and employers have a duty of care to ensure exposure of workers to airborne fibres

remains below the control limits specified by the HSE and as low as is reasonably practicable.

9.4.3. Guideline values for asbestos in soils are currently unavailable but it is accepted that

significant exposure to airborne dust is only likely to occur if the soils are dry and subject to

disturbance by mechanical means or wind erosion. Although limited, release of fibres from the

surface could therefore feasibly occur during the intended use of the site in the absence of

appropriate mitigation and a precautionary approach should be adopted with respect to risks

from this pathway.

9.4.4. Disturbance of the leather wastes in the southern part of Plot 5 could feasibly result in the

release of and exposure to viable pathogens (anthrax spores).

9.4.5. The raised level of lead, in the eastern tip area may pose a risk to human health if widespread

within shallow soils in soft standing areas via ingestion / inhalation / dermal contact, although

the majority of the site is expected to be used as car parking with only limited areas of soft

landscaping, the other metals zinc and copper detected in this area, and the hydrocarbons

present are not at concentrations where health impacts would be anticipated although the

potential for discrete areas of greater contamination within the waste body cannot be

discounted.



th September 2013

38

9.5. Controlled Waters Risk Assessment

9.5.1. The secondary aquifer within the superficial deposits, as well as the underlying secondary

aquifer within bedrock, probably forms part of the base flow for, or is in hydraulic connectivity

with the River Irwell.

9.5.2. No concentrations of any determinant analysed for exceeded EQS screening criteria and the

majority of the determinants were below the laboratory limits of detection. Therefore no

significant risk has been identified with regard to controlled waters and the release of organic

substances from sources within the site.

9.5.3. The inorganic substances reported are unlikely to be significantly soluble; although a minor

ocherous discharge from a culvert crossing the site is present the amount of precipitate

released appears to be relatively minor given the flow within the receiving watercourse.

9.5.4. Although the hydrocarbons reported in TP6 do not appear to be currently impacting the local

groundwater, if a significant reservoir is present such as a relict underground storage tank this

may result in future releases and the proximity of this area to the river could result in minimal

attenuation and a discharge to the surface watercourse.

9.5.5. Although risks to controlled waters are currently assessed as low, and are likely to remain so

following development, as a priority the site preparation and construction works must not result

in the release of polluting materials such as fuels or silt runoff to the drains or local surface

waters.

9.6. Ground Gas/Vapour Risk Assessment

9.6.1. The made ground on the site has a moderate to high organic content, where this is associated

with the ash deposits (including the very high ~50% organic content of ash in one location) this

is likely to be associated with unburnt or partially combusted coke or coal or entrainment of the

underlying organic alluvium. Naturally occurring soil organic matter probably makes up a

significant proportion of the other organic matter detected in the soil matrices, significant

quantities of timber or other organic wastes being absent from the fills exposed during the

investigation.

9.6.2. The alluvial soils present, even if containing bands or pockets of peat material could result in

the accumulation of elevated methane concentrations but generation rates and the potential

from migration are likely to be minimal and impacts are not anticipated. Conditions in the

surrounding area are likely to be similar and no sites with a higher risk of generating significant

ground gas migration with the potential to impact the site have been identified.



th September 2013

39

9.6.3. The investigation results indicate minimal flows/ and differential pressures within gas

monitoring installations, the absence of methane across the entire site, low concentrations of

carbon dioxide and significantly depleted oxygen only encountered near the area of leather

waste in Plot 5, a considerable distance (75m) from the nearest propose planned building.

CIRIA 665 guidance indicates where carbon dioxide concentrations are in excess of 5%

consideration should be given to increasing the characteristic situation to CS2. However due

to the minimal flows encountered on site, these are unlikely to be required, particularly if the

building design can offer some level of intrinsic resistance to gas ingress.

9.6.4. No evidence of significant contamination by common volatile contaminants has been found.

9.6.5. The site is in an area where consideration to risks from radon ingress into buildings should be

considered.

9.7. Property Risk Assessment

9.7.1. It is concluded that the proposed structures are located in an area underlain by variable non-

engineered made ground overlying soft alluvium with competent soils at depth. The proposed

development of the site will include two commercial buildings, roads, car parks, drainage

infrastructure and utility services; some of these could be subject to damage caused by

ground movement unless appropriate site preparation works are carried out and suitably

robust deigns/material specifications are utilised.

9.7.2. Assessment of the stability of the existing slopes and supporting structures is outside the

scope of this assessment; regrading to achieve development levels and acceptable gradients

for access resulting in changes to the slope profiles and the potential for future erosion by the

River Irwell should be considered when assessing any requirements necessitated by the

proposed redevelopment of the site.

9.7.3. Risks to property from potential accumulation and explosion of methane gas are considered to

be minimal.

9.7.4. Some of the metals identified in the made ground within the landfilled area of Plot 5 exceed

standards derived for the protection of sensitive plant species, however it is evident from the

current level of vegetation that only sensitive species, if any, could be impacted and most

parts of the site are anticipated to be used for car parking facilities.

9.7.5. Exceedances of UU criteria for the instalment of PE pipes have been encountered within a

number of locations across the site for hydrocarbons.



th September 2013

40

9.7.6. Soils on the site generally have a low potential to attack concrete structures, however some

variability is anticipated, particularly within the made ground.

9.8. Ecology

9.8.1. A detailed ecological assessment is outside the scope of this assessment; however the

possible presence of protected species (badgers) and invasive species (Japanese Knotweed)

were noted. The influence of these on the planned development should be considered.

9.9. Revised Conceptual Site Model

9.9.1. The revised CSM is summarised overleaf.



th September 2013

41

Table 9.1: Preliminary Conceptual Site Model

Receptor Source / Contaminant Pathway / Exposure Pollutant Linkage (in absence of

mitigation)

Further Assessment/Mitigation

1. humans –

construction

workers / future

maintenance

engineers

Lead, hydrocarbon and asbestos are

present within made ground, the

possibility of viable anthrax spores

exists within the leather wastes


inhalation – short term exposure

Possible – most concentrations of

contaminants recorded are unlikely to

pose an acute or chronic health risk but

asbestos exposure must remain below

control levels and as low s reasonably

practicable and health risks from

pathogens

Control measures to minimise the potential for the

release of airborne normal occupation hygiene and

environmental dust controls are in place, however

measures to control and minimise exposure to

asbestos and prevent exposure to pathogens are

required

Lead, hydrocarbon and asbestos are

present within made ground, the

possibility of viable anthrax spores

exists within the leather wastes


inhalation

Possible – most concentrations of

contaminants recorded are unlikely to

pose an acute or chronic health risk but

mobilisation of asbestos fibres could

result from mechanical disturbance by

vehicle movement and wind erosion

resulting in increased exposure of site

users

Exposure to the lead and other contaminants in the

eastern tip area is unlikely, measures to reduce

generation of dust and release of fibres are

recommended. Car parking is proposed over much of

the site, if soils are recovered during the preparatory

works for re-use in landscaping areas then these

should be subject to some testing to determine their

suitability.

ground gas accumulation to toxic

concentrations within voids,


and ingress into occupied areas

Unlikely – no significant concentrations

of gas/ or significant flow rates recorded;

VOC sources appear to be absent

None

2. humans – future

site workers and

visitors

radon gas from natural ground accumulation within voids,


Possible – site is identified as being in

area where 3-5% properties contain

radon above the action level

A site specific radon assessment could confirm the

status of the site, alternatively installation of basic

precautionary measures may be preferred

ground gas Accumulation to explosive

concentrations within voids,


Unlikely – no significant concentrations

of gas or significant flow rates recorded.

None 3. property /

services

pH, sulphate and organic

contaminants

Chemical attack of buried

concrete and plastic materials

Possible –concentrations of substances

which could attack concrete or water

supply pipes have been reported

A water supply pipeline risk assessment should be

completed and the appropriate classification of

concrete should be used for underground structures



th September 2013

42

Receptor Source / Contaminant Pathway / Exposure Pollutant Linkage (in absence of

mitigation)

Further Assessment/Mitigation

4. vegetation /

landscaping

metals in excess of phytotoxic

screening criteria are present within

made ground in Plot 5

plant uptake Unlikely – moderate concentrations of

phototoxic metals have been identified

but do not appear to be impacting

existing vegetation

Car parking is proposed over much of the site, if soils

are recovered during the preparatory works for re-use

in landscaping areas then these should be subject to

some testing to determine their suitability.

5. ecosystems /

protected species &

habitats

An invasive species is present on the

site. The site may currently provide a

habitat for sensitive species

direct contact / food chain

digestion, colonisation of

sensitive habitats

Possible – The contaminates present

are unlikely to impact the ecology of the

site as impacts to surface waters appear

absent

no action required however the impact of the

proposed development on protected species and

sensitive habitats should be considered

6. surface waters No evidence of contamination from

site affecting surface waters

Migration via drains, surface

runoff and via secondary A

alluvial aquifer into River Irwell

Unlikely – No evidence of contamination

from site affecting surface waters

no action required

7. groundwater No evidence of contamination from

site affecting controlled waters

Infiltration through made ground

and via secondary A alluvial

aquifer into underlying sandstone

Unlikely – No evidence of contamination

from site affecting surface waters

no action required



th September 2013

43

10. Conclusions and Recommendations

10.1. Conclusions

10.1.1. The four Plots into which the site has been divided exhibit differing characteristics including

potential for development constraints associated with soil contamination and the physical

properties of the underlying soils, the plot boundaries are indicated on Drawing 007, together

with the significant features identified in the investigations and risk assessment which are

summarise din greater detail in the following table.

Table 10.1: Summary of Ground Constraints

Plot Description Contamination constraints Geotechnical constraints

1 Former mill area.

Made ground present to 3.1m

bgl underlain by natural

gravels and siltstone bedrock

at 2.2-3.1m bgl.

Presence of asbestos fibre

within made ground.

The constraints identified

(obstructions and variations)

would not significantly impact

the proposed use as a cycle

track

3 Former stone working yard.

Made ground present to 1.5m

in one location, extensive

concrete. Other trial pit

locations did not penetrate

made ground. Natural ground

comprised silt to 3.8m bgl

None identified Extensive obstructions

including concrete, soils

appear consolidated, but with

some localised potential

variability and obstructions;

soft and compressible soils

likely in underlying alluvium.

4 Former concrete batching

plant and infilled river

channel. Made ground

varying in thickness between

0.3-3.6m bgl. Extensive

concrete (generally friable,

occasionally strong and

including rebar). Natural

ground comprising sand, silt

and clay.


within made ground/surface

mounds. Lead, other metals

and hydrocarbon within

eastern tip, although not

presenting health risks.

Possible diesel hotspot in

north.

Extensive obstructions







5 Former tipped areas,

including landfilled area.

Made ground including

extensive concrete on the

western half of the plot

(generally friable,

occasionally strong) to depths

of ~10m proven in boreholes


within made ground/surface

mounds. Lead, other metals

and hydrocarbon within

eastern tip, although not

presenting health risks.

Potential pathogens in leather

waste, which is possibly more

extensive than indicated by

others.

Extensive obstructions







Possible instability of banks

on southern site boundary.



th September 2013

44

10.2. Further Assessment

10.2.1. Currently the main development constraint associated with land contamination is the presence

of asbestos fibre within Plots 4 and 5. Given the distribution of the results it must be currently

assumed that loose fibres at relatively low concentrations are widespread within the made

ground on the site including at shallow depth. Risks from asbestos in soils are only likely if the

substance is at the surface, the soil dry and mechanical disturbance or wind erosion occurs;

these factors could conceivably occur in a car park or cycle track and the uncertainty is

compounded by a lack of robust data on asbestos risks from soil exposure and widely

recognised assessment criteria. Further evidence regarding the distribution of fibres could be

obtained by a more widespread sampling exercise incorporating quantification of

concentrations of asbestos in soils but a degree of uncertainty will remain and given the

perception issues which exist around asbestos exposure and it may be preferable to design

remediation works on the site to prevent the future release of airborne fibres.

10.2.2. No discreet deposits of asbestos containing materials (ACM) were noted on the site and, if

highly localised, additional investigation would be unlikely to identify such deposits if buried; it

is considered more practical to ensure that any remediation strategy for the site includes

provision for dealing with any such deposits if encountered. Detailed examination of the

surface waste deposits and any waste materials being subjected to excavation as part of

regarding works should be carried out in case. If it is proposed to use site-generated recycled

aggregate to form the upper layers of any future surface then these should be subject to

examination for screening for ACM prior to processing and the product screened for asbestos

fibre as well as graded to determine its suitability for this purpose.

10.2.3. Elevated lead with the potential to impact human health in a commercial/industrial landuse

scenario has been identified within a single sample from the eastern tip area. Some

uncertainty regarding the wider extent of metal contamination within the site remains as a

number of the samples could not be analysed for metals due to the presence of asbestos

fibres, however the presence of similar concentrations is considered unlikely to impact human

health given the probable minor areas of soft landscaping to be incorporated within the

planned development; if soils are recovered for re-use during site preparatory works these will

require assessment to determine their suitability for re-use.

10.2.4. The presence of diesel, possibly associated with an underground storage tank, has been

identified in Plot 4. Confirmation of the nature of this source through exploratory trial holes

may be considered beneficial or it could be assumed that the surrounding structures and a

volume of contaminated soil will require removal or treatment. In which case inspection and

validation that the source area has been adequately addressed will be required.



th September 2013

45

10.2.5. Given the lack of hazardous ground gas or leachate discharge into groundwater around the

body of leather wastes in Plot 5, further assessment of this feature is not proposed. Similarly

the lack of groundwater impacts by common industrial pollutants suggest that significant

sources are not present on the site unless contained in some way –this is considered unlikely.

10.2.6. Adoption of piled foundations for the planned built development could provide a failsafe option

for foundation design, however this will be expensive. Alternatively, the type of structure

envisaged may possibly be supported on a raft / pseudo raft foundation depending on its

ability to cater for a degree of differential movement. Further work would be needed to

determine the potential extent of any such settlement under varying surcharges.

10.2.7. Specialist advice may confirm the long-term stability, or otherwise, of the slope up to the

southern site boundary.

10.2.8. Advice from a qualified ecologist should be sought regarding the possible badger sett

identified in the south-eastern part of the site and how this might constrain development

activities.

10.2.9. An invasive plant survey should be carried out by an appropriate person to determine the

extent of the Japanese Knotweed infestation and an appropriate treatment programme.

10.3. Remediation Works

10.3.1. A detailed remediation strategy must be prepared for the site; this is likely to be a requirement

of any conditions attached to Planning Consent for the site. The strategy should detail both

the proposed works required to prepare the site for its intended use, mitigation measures to

address the risks associated with ground contamination as described in this report, provisions

to deal with any unexpected contamination encountered and a validation/verification

programme for the works.

10.3.2. Physical works to prepare the site are likely to consist of a soft strip of vegetation, topsoil and

surface wastes, substantial regrading and at least a partial turnover to shallow depths to

remove obstructions. The significant presence of surface or near surface deposits of concrete

structures and oversized hard materials could yield a substantial volume of aggregate if

recovered and processed on the site which would be of use in the construction phase of

redevelopment. The shallow turnover envisaged to remove obstructions will improve bearing

capacity, provided any soft areas are treated and granular materials are replaced and subject

to an appropriate level of compaction. Mitigation to control dust and prevent unacceptable

release of asbestos fibres will be required during all such earthworks and processing.



th September 2013

46

10.3.3. In the area of leather wastes, as indications of pollution migration appear absent, a policy of

minimal disturbance may be preferable; the preconditions to such an approach are that

development activities do not require excavations in this area or otherwise result in changes

which could promote increases in discharges or emissions from the area. It has been

suggested elsewhere that re-profiling of the adjacent ash bank to improve stability should be

considered; if the toe of the bank was extended north to cover the area of leather waste, then

the additional cover provided would reduce the potential for future exposure and the slope

achieved preclude car parking within the area or other activities which could lead to

disturbance.

10.3.4. If a significant amount of diesel impacted soils or a reservoir such as a relict tank are present

in the area identified in Plot 4, these will require removal or treatment due to their proximity to

the river.

10.3.5. Exposure of future site users to the asbestos identified in the soils is only likely to occur

through release by mechanical disturbance (primarily vehicle movements under the

development scenario under consideration) and wind erosion; it is apparent that some form of

barrier layer be placed over the site surface to block this migration pathway.

10.3.6. If a hard surface for the proposed car parking or the cycle track way within Plot 1 is not

proposed then the presence of low levels of asbestos in any site generated aggregate should

not entirely preclude its use, however such material would require placement in the lower part

of the construction, covered by a suitable a suitable thickness of clean compacted aggregate

to provide a suitable break. A suitable geotextile plced between the layers would act as an

additional break and a warning to the site operators that penetration of the main break layer

has occurred and that repairs are required.

10.3.7. Where vegetated soft landscaped areas are proposed a minimal depth of clean soil cover

should be provided.

10.3.8. Adoption of piled foundations for the planned built development could provide a failsafe option

for foundation design, however his will be expensive. Alternatively, the type of structure

envisaged may possibly be supported on a raft / pseudo raft foundation depending on it’s

ability to cater for a degree of differential movement. Further work would be needed to

determine the potential extent of any such settlement under varying surcharges.

10.3.9. It would be prudent to allow for basic radon protection measures to be installed within the

buildings. Consultation will be required with UU to determine what pipe material will be

suitable. A concrete classification of AC2 in accordance with current BRE guidance is

considered appropriate for buried structures to be constructed on the site.



th September 2013

47

10.4. Limitations

Stratigraphy

10.4.1. The above evidence of stratigraphy is taken from discrete locations. Given the apparently

similar ground conditions between many of the entries, it appears reasonable to infer that

similar conditions may extend between these locations across the majority of the site, although

caution should always be exercised as the nature of the ground does vary between some

entries. In particular depths to natural strata may vary significantly around the former river

channel and the alluvium present over most parts of the site can be anticipated to exhibit a

strong degree of vertical and lateral heterogeneity.

Contamination

10.4.2. The site investigation involved sampling at discrete locations, and it should be recognised that

further areas or types of contamination may exist between investigation positions. The

analyses performed are drawn from a typical suite of tests used to screen potentially

contaminated land, and specified to fall within the available budget. It is always possible that

other substances may be present that have not been included within the standard range of

tests.

Soil gas and groundwater

10.4.3. Any comments made on gas and/or groundwater conditions are based on observations or

tests made at the time that the work was carried out. It should be noted that gas

concentrations and pressures and groundwater levels and concentrations of substances may

vary according to seasonal or weather related effects, sometimes in an unpredictable fashion.

General

10.4.4. This report has been prepared by SGP for the sole and exclusive use of Rossendale Borough

Council. Reasonable skill, care and diligence has been exercised within the budget available,

and in accordance with the technical requirements of the brief. Notwithstanding the efforts

made by the professional team in undertaking the assessment and preparing this report, it is

possible that other ground conditions and contamination as yet undetected may exist.

Reliance on the findings of this report must therefore be limited accordingly. Such reliance

must be based on the whole report and not on extracts which may lead to incomplete or

incorrect conclusions when taken out of context.

10.4.5. SGP reserves the right to alter any of the foregoing information in the event of new information

being disclosed or provided and in the light of changes to legislation, guidelines and

responses by the statutory and regulatory authorities.



h September 2013

DRAWINGS



h September 2013

APPENDIX A

Photographs



h September 2013

APPENDIX B

Site Investigation Logs



h September 2013

APPENDIX C

Chemical Analytical Results



h September 2013

APPENDIX D

Gas Monitoring Results



h September 2013

APPENDIX E

Geotechnical Test Results



h September 2013

APPENDIX F

Landmark Information Group Data

futures park, bacup stage1 & 2 ground investigation for

Documents