Geo-environmental Planning Statement - East Staffordshire Application... · 2011-11-02 · Geo-environmental Planning Statement, Branston West . 4 . 1 Introduction . This document

Geo-environmental Planning Statement

Land South of Branston, Burton-upon-Trent

Branston West

St Modwen Developments Ltd

July 2011

lisa.roberts

Text Box

P/2011/01243 Received 25/10/11

Halcrow Group Limited

Lyndon House, 62 Hagley Road, Edgbaston, Birmingham

B16 8PE

tel 0121 456 2345 fax 0121 456 1569

halcrow.com

Halcrow Group Limited has prepared this report in accordance with

the instructions of client St Modwen Developments Ltd for the client’s sole and specific use.

Any other persons who use any information contained herein do so at their own risk.

© Halcrow Group Limited 2011


Branston West


July 2011

Geo-environmental Planning Statement, Branston West

Document history


Branston West


This document has been issued and amended as follows:

Version Date Description Created by Verified by Approved by

00 31.05.11 Draft for client review S K Trinder D

McFadyean

01 05.07.11 Final S K Trinder D

McFadyean


2

Contents

1 Introduction 4

2 Site details 5 2.1 Site description 5

2.2 Proposed development 5

2.3 Previous reports and studies 5

2.4 Geology 6

2.5 Hydrology 7

2.6 Hydrogeology 7

2.7 Coal mining 8

2.8 Results of Landmark surveys 8

3 Site history 9

4 Conceptual site model 11 4.1 Introduction 11

4.2 Sources 11

4.3 Pathways 11

4.4 Receptors 11

5 Ground investigations 13 5.1 Introduction 13

5.2 Preliminary ground investigation 13

5.3 Ground conditions 13

5.3.1 Topsoil, Made Ground and Alluvium 13

5.3.2 Pulverised Fuel Ash (PFA) 14

5.3.3 Sand and Gravel 15

5.3.4 Mercia Mudstone Group 16

5.3.5 Groundwater 17

5.4 Geotechnical testing 17

5.4.1 Results of geotechnical testing on PFA 17

5.4.2 Results of geotechnical testing on Sand and Gravel 18

5.4.3 Results of geotechnical testing on Mercia Mudstone Group 19

5.5 Geo-environmental testing 19

5.5.1 Results of chemical testing on Made Ground and Alluvium 19

5.5.2 Results of Chemical Testing on PFA 20

5.5.3 Results of chemical testing on Sand and Gravel 22

5.5.4 Results of chemical testing on Mercia Mudstone Group 23

5.5.5 Concrete class 24

5.6 Groundwater and gas monitoring and testing 24


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5.7 Surface water testing 26

6 Site implications 28 6.1 Introduction 28

6.2 Environmental 28

6.2.1 PFA 28

6.2.2 Flooding 28

6.2.3 Groundwater and surface water contamination 28

6.2.4 Ground gas and radon 28

6.3 Geotechnical 29

6.3.1 PFA 29

6.3.2 Gravel abstraction 29

6.3.3 Railway 29

6.3.4 Groundwater 29

6.3.5 Foundations, excavations and obstructions 29

6.3.6 Liquefaction 30

6.3.7 Concrete class 30

6.4 Summary 30

7 References 31

8 Figures 32

Appendices

Appendix A: Halcrow Group Ltd Phase 1 Geo-Environmental Audit, August 2002

Appendix B: Halcrow Group Ltd Phase 2 Geo-Environmental Audit, February 2003

Appendix C: Ian Farmer Associates, Factual Ground Investigation Final Report (2375), March 2003

Appendix D: Ian Farmer Associates, Factual Ground Investigation Final Report (2478), June 2003

Appendix E: Halcrow Group Ltd Phase 2 Geo-Environmental Audit, July 2003

Appendix F: Landmark Report, May 2011


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1 Introduction

This document is a collation of available information on the known geo-

environmental and geotechnical ground conditions for the Branston West site, an area

of land south of Branston, Burton-upon-Trent, Staffordshire, between the A38 to the

west and the Birmingham-Derby railway line in the east. The site has been the subject

of a number of reports, investigations and surveys over the years and the results of

this information are brought together in this Statement.

The location of Branston West is shown in Figure 1.

The Statement has been prepared for St Modwen Developments Ltd to support an

outline planning application for the land south of Branston comprising residential

and B2/B8 industrial units, together with associated roads, hardstanding, landscaping

and planting.

The available information is provided as Appendix A to Appendix F of this report.


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2 Site details

2.1 Site description

The location of Branston West is shown on Figure 1. Historically, in previous reports

the area of Branston West has been divided into Zones 1, 2 and 3 and land to the east

of Branston West was known as Zone 4. Figure 2 shows the location of the Zones

referred to in previous reports. Zone 4, east of the railway, was studied in some of the

previous reports, but does not form part of Branston West for the purposes of this

Planning Statement or the Outline Planning Application it supports

The Branston West development site is located immediately south of Branston in

Staffordshire, centred on approximate National Grid Reference SK 219205 The Site is

bounded to the west by the A38 for much of its length. To the north, the Branston

West is bounded by housing, to the east by the Birmingham-Derby railway and to the

south by farmland and a residential property. The site is divided into fields and is

crossed by a line of electricity pylons and the diverted course of a stream (the

Tatenhill Brook). The stream flows from the west across the site, along the railway

line and passes beneath the railway. There are existing public footpaths within the

site. Ground level in the north of the area is 47m above Ordnance Datum (mAOD),

rising slightly to the south and the site is predominantly flat.

2.2 Proposed development

This Statement supports an outline planning application for the Branston West

development comprising residential areas in the north of the Branston West site and

industrial units in the central and southern areas of the site, together with associated

roads, hardstanding, landscaping and planting.

2.3 Previous reports and studies

Table 2.1 below details previous reports and studies which have been prepared for

the areas including all or part of Branston West. The Zones covered by the reports

have been identified after the report title in italics, where they do not form part of the

report title.

Table 2.1 Previous reports

Date Author Report Title Report Ref Appendix Ref

October

1990

W S Atkins Branston Development, Burton-

on-Trent, Areas 8a and 8b,

Preliminary Site Assessment,

Geotechnical Interpretation

Zones 1, 2 and 3

U2171/GEO

88233/003/ OCT

90

Included in

Halcrow, 2002, in

Appendix A.

December

1990

Geotechnics

Ltd

Phase II Branston Development,

for Branston Development

Partnership

Zones 1, 2 and 3

90 6505 Included in

Halcrow, 2002, in

Appendix A.


6

2.4 Geology

The geology of the site has been determined by reference to British Geological Survey

Map Sheet 140, 1:50,000 Solid and Drift Edition, 1982, and the associated memoir

Geology of the Country between Burton upon Trent, Rugeley and Uttoxeter

(Stevenson IP and Mitchell GH, 1955). Additionally, some ground investigation data

is available (see Table 2.1 above).

January

1992

Farebrother

and Partners

Report on proposed excavations

in fly ash at Branston, Burton on

Trent, for St Modwen

Developments Ltd

RJP/JCR/7820 Included in

Halcrow, 2002, in

Appendix A.

November

2000

W S Atkins Branston Development Prelinary

Site Assessment, for St Modwen

Developments Ltd

Zone 2 and parts of Zones 1 and 3

83/AF0031/MAS Included in

Halcrow, 2002, in

Appendix A.

August

2002

Landmark

Information

Group

Envirocheck Report on Branston,

for Branston Properties

Zones 1, 2, 3 and 4

159184-1-1 Included in

Halcrow, 2002, in

Appendix A.

August

2002

Coal

Authority

Coal Mining Report, Branston,

Staffordshire

Zones 1, 2, 3 and 4

351434-02 Included in

Halcrow, 2002, in

Appendix A.

August

2002

Halcrow

Group Ltd

Branston Properties, Branston,

Phase 1 Geo-Environmental

Audit

Zones 1, 2, 3 and 4

- Appendix A

February

2003

Halcrow

Group Ltd

Miller Homes and St Modwen

Developments Ltd, Branston

Residential, Phase 2 Geo-

Environmental Audit

Zone 1

- Appendix B

March 2003 Ian Farmer

Associates

St Modwen Developments Ltd,

Branston Zone 1, Factual Ground

Investigation, Final Report No.

2375

2375 Appendix C

June 2003 Ian Farmer

Associates

East Staffordshire Borough

Council, Branston Zones 2 & 3,

Factual Ground Investigation,

Final Report No. 2478

2478 Appendix D

July 2003 Halcrow

Group Ltd

East Staffordshire Borough

Council, Land South of Branston

Zones 2 & 3, Phase 2 Geo-

Environmental Audit

- Appendix E

May 2011 Landmark

Information

Group

Envirocheck Report. Site at

Burton upon Trent Staffordshire

Centred on Zone 4 but also covers

Zones 1, 2 and 3

34725405_1_1 Appendix F


7

This geological map indicates that there are drift deposits of Alluvium and 1st River

Terrace Deposits above Mercia Mudstone Group bedrock of Triassic Age.

Previous ground investigations within Branston West did not encounter alluvial

deposits and much of the River Terrace Deposits, comprising sand and gravel, had

been quarried, with the ensuing void backfilled with Pulverised Fuel Ash (PFA). The

PFA filling these former sand and gravel quarries was found to be between 0m and

8.3m thick overlying remnant Quaternary Sand and Gravel across much of the area

which in turn overlies Mercia Mudstone Group deposits.

Further details about the history of the site and the extraction of sand and

gravel/deposition of PFA fill are given in Section 3.

2.5 Hydrology

The River Trent is present approximately 100m east of the site, flowing in a northerly

direction. The Tatenhill Brook enters the site in the south-west, flows east then north-

east parallel to the railway, and then crosses beneath the railway before flowing to the

River Trent.

Large areas within and west and east of the site have had sand and gravel extracted.

Some areas within and east of the site have been filled with PFA whilst some areas

remain as ponds, for example Branston Water Park to the west of the A38.

Branston West lies within the natural floodplain of the River Trent. Some of the site is

shown on the 2011 Envirocheck Report as an area that could be flooded with a 1 per

cent (1 in 100) or greater chance of this happening each year. The remainder of the

site is marked as an area which shows the additional extent of an extreme flood from

the River Trent. These outlying areas are likely to be affected by a major flood, with

up to a 0.1 per cent (1 in 1000) chance of occurring each year. Branston village to the

north (excluding its most southerly houses) is shown as an area benefitting from

flood defences.

2.6 Hydrogeology

The sand and gravel deposits of Branston West are classified by the Environment

Agency as a Secondary A aquifer and the underlying Mercia Mudstone solid deposits

as a Secondary B aquifer.

Secondary aquifers include a wide range of rock layers or drift deposits with an

equally wide range of water permeability and storage.

Secondary A aquifers are permeable layers capable of supporting water supplies at a

local rather than strategic scale, and in some cases forming an important source of

base flow to rivers. These are generally aquifers formerly classified as minor aquifers.

Secondary B aquifers are predominantly lower permeability layers which may store

and yield limited amounts of groundwater due to localised features such as fissures,

thin permeable horizons and weathering. These are generally the water-bearing parts

of the former ”non-aquifers”.

Soil vulnerability classification groups are based on soil physical and chemical

properties which affect the downward passage of water and contaminants. Soils of

class H are considered of high leaching potential, with little ability to attenuate


8

diffuse source pollutants and in which non-adsorbed diffuse source pollutants and

liquid discharges have the potential to move rapidly to underlying strata or to

shallow groundwater.

For much of the northern and central part of the site, the soils are classified as HU.

Soil information for restored mineral workings and urban areas is based on fewer

observations than elsewhere. A worst case vulnerability classification (H) is assumed,

until proved otherwise. In the south of the site, the soils are generally class H2,

described as ‘deep, permeable, coarse textured soils which readily transmit a wide

range of pollutants because of their rapid drainage and low attenuation potential.’ In

the central area, adjacent to the railway, the soils are classed as H1, described as ‘Soils

which readily transmit liquid discharges because they are either shallow, or

susceptible to rapid by-pass flow directly to rock, gravel or groundwater.’

The north of the site forms part of a Source Protection Zone III. This is defined by the

Environment Agency as the area around a groundwater source within which all

groundwater recharge is presumed to be discharged at the source. In confined

aquifers, the source catchment may be displaced some distance from the source.

2.7 Coal mining

A Coal Mining Report was obtained from the Coal Authority in 2002. A copy of the

report is included as Appendix M of Halcrow’s Phase 1 Geo-Environmental Report

(Halcrow, August 2002), reproduced in Appendix A. The Coal Authority records

state the site is not within the zone of likely influence on the surface of past, present

or future planned underground or opencast coal workings. There are no known

shafts or adits within the site. Their records do not disclose any damage notice or

claim being made in respect of the site, and no notice of entitlement to withdraw

support has been published.

2.8 Results of Landmark surveys

The Landmark survey (Landmark Information Group, August 2002) consulted for

previous investigations and reports at the Branston West site is reproduced in

Appendix A of Halcrow’s Phase 1 Geo-Environmental Report (Halcrow, August

2002). Details of the findings of the Landmark survey are given in the same report

reproduced in Appendix A of this Statement.

A Landmark survey was purchased in May 2011 for the adjacent site, Branston East

(between the railway line and the River Trent). Whilst this has not been consulted in

detail for this Planning Statement, a copy has been included for reference in

Appendix F and a full study of this report in relation to Branston West should be

made at the appropriate time in the development process for the site.


9

3 Site history

Ordnance Survey (OS) plans from 1887 to 2000 were obtained from Landmark

Information Group and are contained in Halcrow’s Phase 1 Geo-Environmental

Report (Halcrow, August 2002), reproduced in Appendix A. A selection of aerial

photographs from 1948 to 1993 was obtained from the National Monuments Record

Centre as part of previous studies and also for a recent enquiry into the area of land

east of the railway.

The site pre-existed as fields, at least up to the 1950s. The 1948 aerial photograph

shows an east-west orientated pond across the centre of the site, approximately 50m

wide. This appears man-made and was presumably used for gravel extraction. The

pond was shown on the 1955 OS plan.

By 1962, the main phase of gravel extraction was in progress. Central and northern

parts of the site were ponds, with evidence of ribs of intact material visible,

submerged in some locations. The ponds extended to the western boundary of the

site and close to the railway in the east. Two conveyor belts appear present in the

northern part of the site and the colour of the water is light, suggesting that filling of

the ponds with pulverised fuel ash (PFA) in the northern part of the site was

underway by 1962. The PFA was produced by nearby Drakelow Power Station. One

larger scale photograph from 1967 shows continued evidence of filling with a

conveyor belt crossing the A38. By 1971 reinstatement of the central and northern

part of the site appears complete.

A later phase of gravel extraction was undertaken in the south of the site, shown as

excavations on a 1971 photograph, ponds in 1981 and reinstated by 1989.

The history of the site described below is based on historical Ordnance Survey maps

and historical reports in Table 2.1. A summary is presented in Table 3.1.

Table 3.1 Site history from Ordnance Survey plans

Date Site Description

1887 The Birmingham to Derby railway forms the eastern boundary of the site

along its present-day orientation. A road is shown to the north west of the site

that follows the approximate line of the present A38. Most of the site is fields

with field boundaries shown and Newbold Farm is marked in the south of the

site.

The surrounding land comprises fields with the village of Branston to the

north. The area of land east of the railway is labelled “liable to floods” with

some ponds and a small area of marshland shown. The River Trent flows to

the north; in some parts the the river course differs slightly from its present

day course, in particular to the north the river is some 50m wider.


10

1901 A stream is shown to flow through the site entering at Gallow Bridge, flowing

east then south to a marshy area where it appears to end, a third stream enters

from the west 280m north of Gallow Bridge, flows east under the railway and

then joins the River Trent. Land south of Newbold Farm adjacent to the

railway was marked as marsh.

1902 Some of the field boundaries have been straightened and some have become

tracks or paths. The northwest corner of the site is occupied by a building

labelled as “Sunday School”.

1923 Four cottages have been built south of Gallow Bridge just west of the site,

adjacent to the A38.

1925 No apparent changes to the site.

1937 Only the northern extent of the site is shown. A 20m square mound is shown

at the northern edge of the site.

1938 Only the southern extent of the site is shown. No apparent changes to the site.

1955 The Sunday School building is now labelled as “GP” with another small

building close by. A 350m long pond exists in the centre of the site.

1965 Only the south-western area of the site is shown. Electricity pylons cross the

site, 20m south of Newbold Farm. The southern part of the central area is

labelled as an ash lagoon. The A38 has been widened to approximately 25m

width.

1968 Only the southern extent of the site is shown, no apparent changes to the site

area are shown.

1968/

1970

As 1965 for the southern part of the site. The northern part of the site is shown

as one large field and one smaller, neither with any features shown. The A38

is shown in its present appearance to the west of the site.

1972 Only the northwest of the site is shown. A conveyor belt crosses the north of

the site, separating two areas of featureless expanse.

1975 Only the northern extent of the site is shown, a conveyor is shown crossing the

northern part of the site from east to west. The central area is shown raised

above the land to the south.

1991/

1993

No apparent changes to the northern part of the site, except the conveyor is no

longer shown. The south of the central area is labelled as “ash lagoon”. Drains

are shown north of Newbold Farm.

2000 Newbold Farm is no longer shown.

2006 No apparent changes to the site. Additional housing constructed north of the

site

2011 No apparent changes


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4 Conceptual site model

4.1 Introduction

The preliminary conceptual site model and associated risk assessment has been

developed in accordance with the Environment Agency’s Contaminated Land

Exposure Assessment for both of a ‘commercial’ standard land use and a ‘residential’

end use.

4.2 Sources

Based on the history of the site and surrounding land, the potentially contaminative

land uses and associated potential contaminants of concern are set out in Table 4.1

below.

Table 4.1 Potential sources of contamination

Land use Priority Contaminants of Concern

Onsite: Arable

farmland

Hydrocarbons (fuel spills), pesticides, herbicides and heavy metals

(the latter only if sewage sludge was applied to the land)

Onsite: PFA Aluminium, iron, silicon, carbon, calcium, potassium, sodium and

magnesium, sulphates. Trace elements including arsenic, boron,

cadmium, chromium, copper, manganese, molybdenum, nickel, lead,

sulphur, selenium, titanium, vanadium and zinc. Mercury.

Ash lagoons are noted in the industry profile to potentially contain

metals, metalloids and their compounds, water treatment chemicals,

timber treatment chemicals.

Adjacent to east:

Railway Land

Hydrocarbons, PAH, chlorinated solvents, herbicides, railway ballast

(ash, clinker, slag), anti-freeze (ethylene glycol), VOCs, SVOCs

4.3 Pathways

The following pollutant linkages have been identified for the site based upon site

investigation data and proposed future land use:

• Direct contact with hazardous substances

• Mobilisation of hazardous substances within the ground (leaching) to controlled

waters

• Off site migration through drains and service trenches across the site

• Dust inhalation during works/excavations within the PFA

4.4 Receptors

The following receptors have been identified for the site:

• Residents

• Site users, workers and visitors


12

• Buildings (buried concrete, services)

• Secondary A Aquifer within the sand and gravel deposits

• Tatenhill Brook and streams in the site

• River Trent


13

5 Ground investigations

5.1 Introduction

Ground investigations have been undertaken at the site as detailed in the various

reports included in Table 2.1. It should be noted that the interpretation of chemical

test results in the reports was calculated in accordance with the prevailing standards

at the time of writing. Further details of the materials encountered are provided in

Sections 5.3.1 to 5.3.4 below.

Ground conditions in the northern part of the site (former Zone 1) comprise

Pulverised Fuel Ash (PFA) up to 8.3m thick above Sand and Gravel up to 3.6m thick,

above Mercia Mudstone Group deposits, the top of which was encountered at

between 4.7 and 9.0m below ground level (mbgl). The top 0.1m to 0.5m of the PFA

was described as topsoil or turf in most of the boreholes in the northern section of the

site

Topsoil was encountered over most of the central and southern part of the site and

varied in thickness between 0.1 and 0.7m.

The central area of the site (former Zone 2) was found during investigations to

comprise Pulverised Fuel Ash (PFA) up to 6.9m thick above Sand and Gravel up to

3.6m thick, above Mercia Mudstone Group deposits, the top of which was

encountered at between 4.0 and 8.3m below ground level (mbgl).

The southern part of the site (former Zone 3 North) comprised topsoil up to 0.7m

thick over most of the site with Made Ground in the north of the site up to 2.8m thick,

above clay (in most locations) up to 2.8m thick above Sand and Gravel up to 6m thick

above Mercia Mudstone Group deposits the top of which was encountered at

between 3.0 and 6.0m bgl.

The most southerly part of the site (former Zone 3 South) comprised PFA up to 5.9m

thick above Sand and Gravel up to 3.8m thick, above Mercia Mudstone Group

deposits, the top of which was encountered at between 3.55 and 6.8mbgl.

Notes are made below of the ground conditions encountered in the preliminary

ground investigation specified by Halcrow in 2002, and the results of more detailed

ground investigation, monitoring and testing during 2002-2003.

5.2 Preliminary ground investigation

A preliminary ground investigation consisting of eight trial pits to a depth of 8m was

undertaken on 1 July 2002 in the northern and central parts of the Branston West site

(former Zones 1 and 2). The investigation found the Pulverised Fuel Ash (PFA) to be

at least 4.0m thick and, in all but two of the trial pits, gravel was encountered beneath

the PFA. The gravels were very unstable, with the sides of the excavation collapsing.

Heavy groundwater inflows were encountered at the level of the gravels

approximately 4.0 to 4.4m below ground level. Mercia Mudstone was encountered at

6.0m below ground level in TP 1, 6 and 8.

5.3 Ground conditions

5.3.1 Topsoil, Made Ground and Alluvium


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(a) Northern part of the site (former Zone 1)

The top 100mm to 500mm of the PFA was described as topsoil or turf in most of the

boreholes in the northern section of the site (former Zone 1).

At the base of six boreholes in northern section of the site (former Zone 1), a silty

material was encountered, described as uncompact, mottled grey brown silt, which

was logged as possible made ground and in one borehole a “fairly strong foul or

chemical odour” was noted.

(b) Central and southern parts of the site (former Zones 2 and 3)

Topsoil was encountered over most of the southern and central parts of the site

(former Zones 2 and 3) and varied in thickness between 0.1 and 0.7m.

Made Ground was encountered in BH122 in the north of former Zone 3 North and

was described as firm brown, slightly gravelly sandy clay with occasional roots and

the gravel fraction consisting of fine to coarse subangular clinker.

Made Ground was also encountered in the south of former Zone 3 South and was

described as brown slightly gravelly sandy silt with the gravel fraction described as

medium to coarse angular to subangular gravel containing clinker in one location.

The thickness of the made ground varied from 0.5 to 1.0m.

Soft to firm grey brown sandy to very sandy clay was encountered in some areas of

former Zone 3 North. Its thickness varied from zero to 2.9m. Only one Standard

Penetration Test was undertaken within the material and this recorded an N value of

7 at 1.0m depth. The location of this material close to the Tatenhill Brook indicates

that it is alluvial in origin.

5.3.2 Pulverised Fuel Ash (PFA)


During investigations of the northern part of the site by Ian Farmer Associates

(Report 2375, 2003), PFA was encountered in all but two window sample holes which

were located at the edges of the site. The top 100mm to 500mm of the PFA was

described as topsoil or turf in most of the boreholes. After rainfall it was noted that

the surface became ponded and soft making drive-on access difficult.

The PFA was described as a grey sandy silt, mostly uncompact. Close to the footpath

crossing the site and in the north-western area of the former Zone 1, the top 3m to 4m

of PFA was found to be dense to medium dense.

The depth of the PFA was variable, from zero at the edges of the site to 8.3m in the

north-west. The shallowest areas of PFA were typically 3.5m thick and approximate

contours of the thickness of PFA are shown in Figure 5 of Halcrow’s 2003 report,

Miller Homes and St Modwen Developments Ltd, Branston Residential, Phase 2 Geo-

Environmental Audit. The PFA was found to extend close to the sides of the site,

estimated to be formed at side slopes typically of up to 1v:2.5h along the western

edge and 1v:4h along the eastern edge of the site.


15

Standard Penetration Tests within the PFA recorded ‘N’ values between 1 and 23

with an average of 9. The top 2.5m to 3.0m of PFA was generally loose to medium

dense and below 2.5m to 3.0m was very loose to medium dense.


PFA was encountered in former Zone 2 and former Zone 3 South. It was described as

“uncompact, grey gravelly silt, gravel is medium to coarse subangular to

subrounded”. An indication of the strength of the PFA has been given in the borehole

logs and is based on the Standard Penetration Test results obtained during drilling

(as summarised in Figure 7 of Halcrow’s 2003 report, East Staffordshire Borough

Council, Land South of Branston Zones 2 & 3, Phase 2 Geo-Environmental Audit,

reproduced in Appendix E). Standard Penetration Test N values decrease from

approximately 10 to 4 at approximately 2m below ground level. The dynamic probe

results through the PFA confirmed a distinctive increase in strength above between

0.8m and 2.0m below ground level.

The depth of PFA varied from zero to 6.9m below ground level. No PFA was

encountered across former Zone 3 North, around the edges of former Zone 3 South

and the west, southern and eastern edges of former Zone 2. The maximum depth of

PFA was recorded in the centre of former Zone 2 (as shown in Figure 4 of Halcrow’s

2003 report, East Staffordshire Borough Council, Land South of Branston Zones 2 & 3,

Phase 2 Geo-Environmental Audit, reproduced in Appendix E). It is possible that

there are steep buried slopes at the interface between the PFA and the remnant

unworked Sand and Gravel.

5.3.3 Sand and Gravel


Sand and Gravel was present across most of the site except on the eastern boundary

(as shown in Figure 6 of Halcrow’s 2003 report, Miller Homes and St Modwen

Developments Ltd, Branston Residential, Phase 2 Geo-Environmental Audit,

reproduced in Appendix B). It was encountered at depths of between 3.5m and 8.5m

below ground level and was up to 3.6m thick. It was described as a medium dense

grey brown fine and medium sand and gravel. The gravel fraction was fine to coarse,

subangular to rounded and in the west of the former Zone 1, occasional small cobbles

were found.

Standard Penetration Tests within the Sand and Gravel recorded N values from 9 to

40 with an average value of 18, which characterised the deposit generally as medium

dense to dense.


Sand and Gravel was present across most of the site except on the eastern side of

former Zone 3 South and the centre and east of former Zone 2 (as shown in Figure 5

of Halcrow’s 2003 report, East Staffordshire Borough Council, Land South of

Branston Zones 2 & 3, Phase 2 Geo-Environmental Audit, reproduced in Appendix

E). It was encountered at depths of between 0.2 and 6.9m below ground level and was

up to 6.0m thick. It was described as a medium dense occasionally loose red brown

and grey medium to coarse Sand and Gravel, with occasional subrounded cobbles.

The gravel fraction was fine to coarse, rounded to subangular.


16

Standard Penetration Tests within the Sand and Gravel recorded N values from 8 to

36 with an average value of 15, which characterised the deposit generally as medium

dense, as shown in Figure 8. Using the relationship given in CIRIA report 143 (1995)

this corresponds to a phi-value of between 30° and 40° with a design value of 31°.

5.3.4 Mercia Mudstone Group


The depth to the top of the mudstone encountered in the northern part of the site

(former Zone 1) varied from 4.7m to 9.0m, with an approximate dip to the north-west

of 0.5º. It was described as stiff to very stiff red brown clay with occasional grey green

mottling with some fine to medium gravel sized lithorelicts. The top of the mudstone

was Weathering Grade 4a to 3. The Mercia Mudstone was penetrated to a maximum

thickness of 7.5m (14.0m bgl). Average penetration into the mudstone was 5.3m

(approximately 11.1m bgl), considered to be the approximate boundary between

Weathering Grades 2 and 3.

Standard Penetration Test N values within the Mercia Mudstone Group varied from

14 to greater than 50 blows for 150mm penetration. SPT N value increased with depth

(as shown in Figure 9 of Halcrow’s 2003 report, Miller Homes and St Modwen

Developments Ltd, Branston Residential, Phase 2 Geo-Environmental Audit).

Weathering Grade 4 is represented by an SPT N value of less than 30 blows and this

was generally found at depths of less than 8.0m bgl. Below this the mudstone was

less weathered.


In central and southern parts of the site, the top surface of the Mercia Mudstone

Group was found at between 40.16 m and 44.85 m above Ordnance Datum and was

penetrated by the investigation to a further depth of up 9.4m. It was found to be

variable in composition across the site. In former Zone 2 and former Zone 3 North it

was described as firm to stiff friable red brown, with green mottling, clay increasing

in strength with depth to weak grey green mudstone.

In former Zone 3 South the maximum depth of penetration into the Mercia Mudstone

Group was 1.5m. Siltstone and mudstone were encountered at between 4.0 m and 6.1

m bgl. The siltstone was described as moderately weak grey siltstone and the

mudstone was described as very weak to moderately weak light green and grey

sometimes fissile mudstone.

Standard Penetration Test N values within the Mercia Mudstone Group varied from 9

to refusal (as shown in Figure 9 of Halcrow’s 2003 report, East Staffordshire Borough

Council, Land South of Branston Zones 2 & 3, Phase 2 Geo-Environmental Audit,

reproduced in Appendix E). The graph shows the N value increases with depth from

approximately 10 at 6mbgl to approximately 23 at 14mbgl. Using the relationship

given in CIRIA report 143 (1995) this corresponds to phi of between 28° and 36° with

design value of 30°. Mercia Mudstone Weathering grade 3, as indicated in CIRIA

C570, is present when the SPT N value is greater than 30, implying that weathering

grade 3 is present at depths of greater than approximately 16m below ground level in

Zone 2. Weathering Grade 4 is present across the top surface of the Mercia Mudstone


17

in Zone 2and is approximately 10m thick. The presence of siltstone bands in Zone 3

has decreased the thickness of the weathered zone to 1.5m.

5.3.5 Groundwater


During investigations groundwater was encountered within the PFA, sand and

gravels and the Mercia Mudstone Group.

In the PFA, water was encountered at depths between 0.2m and 5.0m bgl. Most water

strikes during drilling were at depths between 1.5m and 3.0m bgl. Three boreholes

had two water strikes within the PFA, indicating perched water tables in the PFA.

Water in the Sands and Gravels was generally encountered close to the top of the

deposit and the level rose between 0.4m and 2.8m in 20 minutes.

Water strikes in the Mercia Mudstone were at depths between 6.7m and 8.1m bgl.


In the central and southern parts of the site, groundwater was encountered in most of

the boreholes during installation close to the top of the Sand and Gravel. In areas

with PFA the groundwater level generally rose rapidly from 3-7mbgl (ie within the

Sand and Gravel) to between 1.0m and 1.5mbgl within 20 minutes. Two boreholes

(BH112 and BH117) did not record water strikes during drilling nor encountered

Sand and Gravel deposits.

5.4 Geotechnical testing

Testing of the PFA, Sand and Gravel and Mercia Mudstone was carried out. Detailed

results of these tests are contained in:

• Ian Farmer Associates, St Modwen Developments Ltd, Branston Zone 1, Factual

Ground Investigation, Final Report No. 2375, 2003 for the northern part of the site

(former Zone 1)

• Ian Farmer Associates, East Staffordshire Borough Council, Land South of

Branston Zones 2 & 3, Factual Ground Investigation, Final Report No. 2478, June

2003 for the central and southern areas of the site (former Zones 2 and 3).

A summary is as follows:

5.4.1 Results of geotechnical testing on PFA

The natural moisture content of 39no. samples of PFA from the northern area and 66

no. samples from the central/southern areas was determined and found to vary

between 5.2% and 61% with a median value of 46% in the north and 44% in the

central/southern parts of the site.

23no. Atterberg limit tests were attempted and all but one of the samples were non-

plastic. The one successful test had a liquid limit of 89%, a plastic limit of 37% and a

plasticity index of 44%, classifying this sample as a silt of very high plasticity. One

sample of silt from the base of the PFA was classified as a high-plasticity clay (liquid

limit 59%, plastic limit 32% and plasticity index 27%).


18

Five particle size distributions from the northern part of the site showed the PFA to

comprise 1% to 24% clay, 47% to 74% silt, 2% to 37% sand and 0 to 8% gravel. Five

samples from the central and southern part of the site showed the PFA to contain 11

to 89% silt/clay, 11 to 36% sand and 0 to 53% gravel.

The pH and water soluble sulphate content of six samples tested from across the

whole site varied from 8.1 to 9.7 for pH and 0.09 to 1.19g/l for soluble sulphate.

Eight unconsolidated undrained triaxial tests were carried out on undisturbed

samples of PFA and the undrained shear strength varied from 19kPa to 98kPa, with

no apparent correlation with depth or spatial distribution. Two samples in borehole

B27 showed a decrease in strength from 21kPa to 15kPa from 1m to 2m depth.

Effective strength tests carried out on four undisturbed samples of PFA recorded an

effective cohesion of between 6.7kPa and 7.8kPa and effective angle of internal

friction Ø’ between 12.4º and 17.1º.

Consolidation tests on five samples of PFA recored a decrease in consolidation

coefficient from 0.10 to 0.06 m2/MN in the vertical stress range of 50 to 100kPa,

indicating a material of medium to low compressibility.

Compaction tests were undertaken using two different compactive efforts. Two tests

using a 2.5kg rammer on samples from the northern part of the site recorded

maximum dry densities of 1.4 and 1.5 Mg/m3 at optimum moisture contents of 15.5%

and 14.9% respectively. One compaction test on PFA form the southern/central part

of the site using a 4.5kg rammer recorded a maximum dry density of 1.3 Mg/m3 at an

optimum moisture content of 22%.

One CBR test on a sample of PFA from a depth of 0.5m recorded CBR’s of 0.2% and

0.4% at 46.6% and 44% moisture content respectively.

Two rising head permeability tests in the PFA recorded permeabilities between 1.43 x

10-5 and 2.28 x 10-5 m/s.

Three in situ resistivity tests on the PFA recorded values of between 3597 Ωm and

5514Ωm. Three in situ redox tests recorded a redox potential of between 530mV and

562mV.

5.4.2 Results of geotechnical testing on Sand and Gravel

Four particle size distribution tests from the northern part of the site showed the Sand

and Gravel to comprise between 0% and 5% silt, 8% to 31% sand and 67% to 91%

gravel.

Four particle size distribution tests on samples from the central and southern part of

the site showed the Sand and Gravel to contain 0% to 8% silt/clay, 3% to 59% sand

and 40% to 97% gravel, generally slightly finer than the samples tested from the

north.

Two rising head permeability tests in boreholes in the gravel in the northern part of

the site recorded a permeability of approximately 8.2 x 10-4 m/s.

The pH and water soluble sulphate content of four samples tested varied from 7.9 to

9.2 for pH and 0.09 to 1.75g/l for soluble sulphate.


19

One in situ test recorded a redox potential of 538mV.

5.4.3 Results of geotechnical testing on Mercia Mudstone Group

The natural moisture content of seven samples of Mercia Mudstone was determined

and found to vary between 14% and 22% with a median value of 19%. One high

result of 5% was recorded in a sample from the top of the Mercia Mudstone in a

location where no sand or gravel was present.

Seven Atterberg limits tests were performed and the liquid limit varied from 24 to

39%, the plastic limit varied from 14 to 20% and the plasticity index varied from 8 to

19%, classifying all but one of the samples as a clay of low plasticity with an

anomalous result as a clay of intermediate plasticity. One sample was non-plastic.

Two rising head permeability tests in boreholes in the mudstone in the northern part

of the site recorded a permeability of approximately 4.5 x 10-5 m/s.

The pH and water soluble sulphate content of one sample tested recorded 8.6 for pH

and 0.16g/l for soluble sulphate respectively.

One particle size distribution test shows the Mercia Mudstone to be 60% silt/clay, 30%

sand and 10% gravel.

One in situ resistivity test in the Mercia Mudstone recorded 6164 Ωm.

5.5 Geo-environmental testing

The full results of the laboratory testing are included in:

• Ian Farmer Associates, St Modwen Developments Ltd, Branston Zone 1, Factual

Ground Investigation, Final Report No. 2375, March 2003 for the northern part of

the site (former Zone 1)

• Ian Farmer Associates, East Staffordshire Borough Council, Branston Zones 2 & 3,

Factual Ground Investigation, Final Report No. 2478, June 2003 for the central and

southern areas of the site (former Zones 2 and 3).

The range of potentially hazardous substances analysed was generally limited to

17no. substances listed in Table 3 (Group A and B) and Table 4 of the

Interdepartmental Committee on the Redevelopment of Contaminated Land (ICRCL)

document ICRCL 59/83 “Guidance on the Assessment and Redevelopment of

Contaminated Land” plus some additional determinands as detailed below. This

document was withdrawn from use by Defra in November 2004, but was current at

the time of the ground investigation works. Similarly details are given below of the

determinands tested during leachate analysis and the thresholds used for

comparison, which were current at the time of the ground investigation works.

5.5.1 Results of chemical testing on Made Ground and Alluvium

Two samples of Made Ground and two of Alluvium from the central and southern

areas of the site were tested for the ICRCL suite of determinands plus aluminium,

barium, calcium, manganese, molybdenum and potassium. None of the samples gave

elevated concentrations in comparison to the above described thresholds.


20

Leachable extracts from one of the Made Ground samples and both of the Alluvium

samples were then tested for the EA LQT suite plus aluminium, barium, calcium,

manganese, molybdenum and potassium. Results where concentrations exceeded the

respective threshold value are summarised below in Tables 5.1 and 5.2.

Table 5.1 Summary of elevated results from Made Ground leachate samples

Determinand Threshold level * (µg/l)

Highest level (times

threshold)

No/ of samples above threshold level / no. tested

Mercury 1.0 EA 3.1 (x 3.1) 1/1

Phenol 0.5 WS 4.4 (x 8.8) 1/1

Iron 1 EA 9.7 (x 9.7) 1/1

Aluminium 0.2 WS 13 (x 65) 1/1

* EA denotes EA EQS, WS denotes Water Supply (Water Quality) Regs 2000 and 1989 for Phenol and

Potassium

Table 5.2 Summary of elevated results from Alluvium leachate samples



threshold)


Arsenic 50 EA 51 (1.02) 1/2

Chromium 150 EA 160 (10.7) 1/2

Lead 20 EA 81 (x 4.05) 2/2

Copper 1 EA 49 (x 49) 2/2

Zinc 75 EA 250 (x 3.3) 2/2

Phenol 0.5 WS 3.0 (x 6) 2/2

Iron 1 EA 52 (x 52) 2/2

Aluminium 0.2 WS 24 (x 120) 2/2


Potassium

5.5.2 Results of Chemical Testing on PFA

In the northern part of the site, 26no. samples of PFA were tested for the

determinands listed in ICRCL Tables 3 Groups A and B plus the metals barium and

molybdenum. The results that exceeded the then threshold values for residential use

with plant uptake are summarised in Table 5.3 below.

Table 5.3: Summary of chemical tests on PFA soil samples – northern site area

Determinand Threshold level *

(mg/kg)


threshold)

No of samples

above threshold

level


21


(mg/kg)


threshold)

No of samples

above threshold

level

Arsenic 20 CLEA 100 (x 4.2) 25/26

Boron 3 ICRCL 49 (x 15.3) 13/26

Copper 130 ICRCL 250 (x 1.9) 1/26

Nickel 50 CLEA 100 (x 2.0) 18/26

Barium 625 Dutch 1600 (x 2.5) 11/26

* CLEA denotes Environment Agency guidelines for residential with plant uptake, ICRCL denotes ICRCL

threshold concentration where plants are to be grown, Dutch denotes Dutch intervention value

The soil testing results above indicates that the majority of the determinands tested

for were below the threshold limits. 17 of the samples recorded a pH of above 9.5

with a maximum value of 12.3.

The leachable extracts from seven samples were tested for the EA LQT suite plus

barium and molybdenum. In addition three of the samples were tested for

manganese, aluminium, calcium, potassium, magnesium and sodium. The results

that exceeded the threshold values are summarised below in Table 5.4.

Table 5.4 Summary of PFA leachate testing – northern site area



threshold)


Arsenic 10 EA 15 (x 1.5) 6/7

Cadmium 1 EA 4 (x 4) 1/7

Chromium 50 EA 140 (x 2.8) 1/7

Lead 50 EA 130 (x 2.6) 1

Mercury 1.0 EA 1.3 (x 1.3) 2/7

Copper 20 EA 110 (x 5.5) 1/7

Boron 2000 2400 (x 1.2) 1/7

pH 5.5 – 9.5 EA 10 6/7

Aluminium 200 DW 4600 (x 23) 3/3

Iron 100 EA 1900 (x 19) 5/7

Manganese 50 DW 80 (x 1.6) 2/3

Molybdenum 300 Dutch 310 (x1.03) 1/7

COD 30 us/cm EA 270 (x 9) 6/7

* EA denotes EA LQT, DW denotes UK Drinking Water Standards, Dutch denotes Dutch Intervention vale

for groundwater


22

In the central and southern parts of the site, 53no. samples of PFA were tested for the

ICRCL suite of determinands plus aluminium, barium, calcium, manganese,

molybdenum and potassium. Those of the results that exceeded the threshold values

are summarised in Table 5.5.

Table 5.5: Summary of chemical tests on PFA soil samples – central and southern site area


(mg/kg)


threshold)

No of samples

above threshold

level

Barium 625 Dutch 910 (x 1.5) 2/53

* Dutch denotes Dutch Intervention value

The leachable extracts from 33 samples of PFA were then tested for the EA LQT suite

plus aluminium, barium, calcium, manganese, molybdenum and potassium. The

Environment Agency Environmental Quality Standards (EQS) were used as

threshold values for the assessment of the test results on water and leachate samples.

Where EQS’s are not specified for a particular determinand The Water Supply (Water

Quality) Regulations 2000 (and 1989 for Phenol and Potassium) were used. Those of

the results that exceeded the threshold values are summarised in Table 5.6.

Table 5.6 Summary of elevated leachate results on PFA – central and southern area



threshold)


Mercury 1.0 EA 27 (x 27) 9/33

Copper 1 EA 12 (x 12) 1/33

pH 9 EA 10.2 (x 1.1) 8/33

Phenol 0.5 WS 15 (x 30) 24/33

Iron 1 EA 4.9 (x 4.9) 1/33

Aluminium 0.2 WS 6.4 (x 32) 30/33


Potassium

5.5.3 Results of chemical testing on Sand and Gravel

In the northern part of the site, two samples of Sand and Gravel were tested for the

determinands listed in ICRCL Table 3 Groups A and B plus the metals barium and

molybdenum. The results that exceeded the threshold values for residential use with

plant uptake are summarised in Table 5.7 below.

Table 5.7: Summary of chemical tests on Sands and Gravels – northern site area


23


(mg/kg)


threshold)

No of samples

above threshold

level

Boron 3 ICRCL 11 (x 3.7) 1/2


concentrations where plants are to be grown.

The samples recorded pH values of 9.2 and 9.0.

Five samples of Sand and Gravel from the central and southern areas of the site were

tested for the ICRCL suite of determinands plus aluminium, barium, calcium,

manganese, molybdenum and potassium. The threshold levels used in the

assessment of the results were the published (at the time of the assessment)

Environment Agency CLEA soil guideline values for “Commercial/industrial” end

uses. Where published CLEA values were not available the results had been

compared to the Dutch Intervention Values. Although these latter values have no

official recognition in the UK they are recognised in another European Member State

with a generally more sensitive water environment and have been used here for

comparison only. None of the results was recorded as elevated for the contaminants

tested.

The leachable extracts from two samples were then tested for EA LQT suite plus

aluminium, barium, calcium, manganese, molybdenum and potassium the results

that exceeded the threshold values are summarised in Table 5.8.

Table 5.8 Summary of elevated leachate results on Sand and Gravel – southern and central site area



threshold)

No. of samples above threshold level / no. tested

Mercury 1.0 EA 1.4 (x 1.4) 1/2

Copper 1.0 EA 58 (x 58) 1/2

Phenol 0.5 WS 4.7 (x 9.4) 2/2

Iron 1.0 mg/l EA 5.2 mg/l (x 5.2) 2/2

Aluminium 0.2 mg/l WS 6.4 mg/l (x 32) 2/2

Manganese 0.05 mg/l WS 3.1 mg/l (x 62) 1/2


Potassium

5.5.4 Results of chemical testing on Mercia Mudstone Group

In the northern part of the site, three soil samples of the Mercia Mudstone Group

were tested for the determinands listed in ICRCL Tables 3 Groups A and B plus the

metals barium and molybdenum. The results that exceeded the threshold values for

residential use with plant uptake are summarised in Table 5.9 below.

Table 5.9: Summary of chemical tests on Mercia Mudstone Group – northern site area


24


(mg/kg)


threshold)

No of samples

above threshold

level

Nickel 50 CLEA 51 (x 1.02) 1/3

Boron 3 ICRCL 11 (x 3.7) 1/3


concentrations where plants are to be grown.

The samples recorded pH values of 10.3, 10.1 and 9.5.

Five samples of Mercia Mudstone Group from the central and southern areas of the

site were tested for the ICRCL suite of determinands plus aluminium, barium,

calcium, manganese, molybdenum and potassium. The threshold levels used in the

assessment of the results were the published Environment Agency CLEA soil

guideline values for “Commercial/industrial” end uses. Where published CLEA

values were currently not available the results have been compared to the Dutch

Intervention Values. Although these latter values have no official recognition in the

UK they are recognised in another European Member State with a generally more

sensitive water environment and have been used here for comparison only. None of

the results was recorded as elevated for the contaminants tested.

5.5.5 Concrete class

The pH value and water soluble sulphate content was analysed in 31no. soil samples

and seven groundwater samples. The recorded concentration range of 0.1 g/l to 3.1 g/l

water soluble sulphate and pH range 7.6 to 8.8 is indicative of a Design Sulphate

Class DS-2 and ACEC Class AC-2 in accordance with Building Research

Establishment Special Digest 1.

5.6 Groundwater and gas monitoring and testing


Groundwater monitoring in 11 standpipes on 1 November 2002 showed groundwater

levels between 1.31m and 3.31m bgl. Further monitoring of groundwater levels was

undertaken on six occasions. A contour plan of groundwater levels is shown in

Appendix C of Halcrow’s 2003 report, Miller Homes and St Modwen Developments

Ltd, Branston Residential, Phase 2 Geo-Environmental Audit, reproduced in

Appendix B.

Groundwater sampling and testing was undertaken on five occasions. Speciated PAH

testing if water in B01 indicated that hydrocarbons present were naphthalene and

acenaphthene. A comparison of results for B01 and B38 over time showed a decrease

in the concentrations of arsenic, mercury, selenium and copper to below EA LQT

threshold values and an increase in the level of COD to above the EA LQT level.

Boron, sulphate and pH were consistently above the EA LQT and potassium was

consistently above the UK Drinking Water Standards threshold.


25

Gas monitoring was undertaken in the northern area of the site on 1 November 2002

in eight installations. No carbon monoxide, carbon dioxide, methane or hydrogen

sulphide was recorded. Oxygen concentrations varied from 20.3% to 20.9% by

volume in air. Atmospheric pressure at the time of monitoring was 1001mb. Flow

rates varied from 0.4 l/h to -0.3 l/h.

Five further sets of gas monitoring were carried out, with ambient atmospheric

pressure below 1000mb on one occasion. Results showed oxygen levels varied from

15.5% to 21.1% by volume in air. Carbon dioxide readings were 0% on three

occasions. During one set of readings, B27 recorded 0.2% C02; on a further occasion,

four boreholes recorded 0.2% and B27 recorded 3.9%. Methane was generally 0%,

except on one occasion when 11 boreholes recorded levels up to 0.4% and one

recorded 2.2% (B09). B09 also recorded 2.2% during a separate set of readings.

Hydrogen sulphide was recorded as zero except on one occasion in B01 when a level

of 0.1% was measured. No carbon monoxide was recorded.Flow rates measured

varied form -0.3 l/h to 1.11 l/h.


Ground gas and groundwater monitoring was carried out in nineteen boreholes with

standpipe installations in the central and southern parts of the site weekly for four

weeks in early 2003. Results show that the groundwater flow direction was

approximately from south-west to north-east.

Ground gas monitoring at the site recorded oxygen concentrations between 20.8%

and 18.1% by volume in air with one anomalous reading of 37.6% in BH138 on 20

April 2003 and a second of 16.9% in BH110 on 22 May 2003. Carbon dioxide varied

from zero to 1.3%, methane varied from zero to 0.9% and hydrogen sulphide varied

from zero to 0.4ppm. The flow rate varied from –0.9 to 0.6l/h. Atmospheric pressure

at the time of the readings varied from 997 to 1019mbar.

Chemical testing was carried out on the water samples obtained during the

monitoring on two occasions. The first set of nineteen samples collected on 29 April

2003 were all tested. A second set of samples was collected on 14 May 2003 and nine

of the samples were tested. On each occasion the samples were tested for the EA LQT

suite plus aluminium, barium, calcium, manganese, molybdenum and potassium.

The results that exceeded the threshold values are summarised in Tables 5.10 and

5.11.

Table 5.10 Summary of elevated chemical results on groundwater sampled on 29 April 2003

Determinand Threshold

level * (µg/l unless stated)


threshold)

No of samples above threshold level/ no tested

Cadmium 5 EA 8 (x 1.6) 1/19

Lead 20 EA 110 (x 5.5) 1/19

Copper 1 EA 24 (x 24) 6/19

Zinc 75 EA 5000 (x 67) 15/19


26




threshold)


Sulphate 250 WS 708 (x 2.8) 11/19

pH 9 WS 11.1 (x 1.2) 7/19

Iron 1 EA 3.76 (x 3.76) 2/19

Aluminium 0.2 WS 3.13 (x 16) 6/19

Potassium 12 WS 160 (x 13) 2/19


Potassium

Table 5.11 Summary of elevated chemical results on groundwater sampled on 14 May 2003




threshold)


Lead 20 EA 24 (x 1.2) 1/9

Copper 1 EA 36 (x 36) 3/9

Sulphate 250 WS 456 (x 1.8) 6/9

pH 9 WS 12 (x 1.3) 3/9

Iron 1 EA 6 (x 6) 5/9

Aluminium 0.2 WS 9.8 (x 49) 9/9

Manganese 0.5 WS 0.75 (x 1.5) 1/9

Potassium 12 WS 190 (x 15.8) 8/9


Potassium

5.7 Surface water testing

Surface water samples were taken from five locations along the Tatenhill Brook on

two occasions, in December 2002 and January 2003. The results of the chemical testing

from 20 December 2002 are presented in Table 5.12 below.

Table 5.12 Summary of surface water testing 20 December 2002




threshold)


Arsenic 10 EA 19 (x 1.9) 1/5


27




threshold)


Chromium 20 EA 30 (x 1.5) 1/5

Selenium 10 EA 12 (x 1.2) 2/5

Boron 2000 EA 4000 (x 2) 2/5

Sulphate 150 mg/l EA 1068 (x 7.12) 5/5

Ammonia 0.5 mg/l EA 1.37 (x 2.74) 1/5

Chloride 200 mg/l EA 460 (x 2.3) 1/5

COD 30 mg/l EA 550 (x 18) 5/5

Electrical

conductivity

1000 μs/cm 2100 (x 2.1) 3/5

Iron 0.1 mg/l EA 1.5 (x15) 5/5

Magnesium 50 mg/l UK 67 (x 1.34) 2/5

Molybdenum 0.3 mg/l Dutch 0.59 (x 1.97) 4/5

Sodium 150 mg/l UK 250 (x 1.7) 1/5

Potassium 12 mg/l UK 65 (x 5.4) 4/5

PAH 0.2 EA 0.6 (x 3) 1/5

* EA denotes EA LQT, DW denotes UK Drinking Water Standards, Dutch denotes Dutch Intervention vale

for groundwater


28

6 Site implications

6.1 Introduction

Environmental and geotechnical implications for the site are summarised below, on

the basis of the historical records and results and assessment of ground investigations

and monitoring undertaken previously.

6.2 Environmental

6.2.1 PFA

The PFA may contain elevated levels of potential contaminants typically associated

with PFA (e.g. arsenic, cadmium, selenium and copper) in addition it is likely to have

a high pH.

Elevated concentrations of substances including arsenic, boron, copper, nickel,

barium, aluminium, iron, manganese, high pH and some cadmium, lead, chromium,

molybdenum, mercury have been identified within the PFA (and the groundwater

within and below it) across the site. Human health exposure to these elevated levels is

only likely to occur in back garden areas of the houses as foundations and hard

standing will otherwise provide a barrier to end users of the site. Site end users will

need to be further protected from these elevated levels by adding a suitable cover

system of inert soil and topsoil.

The scarcity of vegetation at the site is symptomatic of the presence of phytotoxic

elements within the PFA and/or the general lack of a growing medium (topsoil) with

sufficient nutrients.

6.2.2 Flooding

The geoenvironmental implications of any proposed flood defence/ alleviation

measures for the site will need to be assessed when the details of the proposed

scheme are known.

6.2.3 Groundwater and surface water contamination

The potential for groundwater contamination (within a total catchment Source

Protection Zone) exists from material leaching out of the PFA on the site. This may

impact the Tatenhill Brook which crosses the Central Area.

Testing of the Tatenhill Brook and ground water at the site has indicated that

elevated levels of some substances are present. These substances however appear to

be present where the Brook enters the site and only small apparent increases are

shown between entering and leaving the site.

6.2.4 Ground gas and radon

Ground gas may be migrating to the site from nearby landfill sites or being produced

on the site from the PFA. Monitoring of ground gas in the site has indicated that

passive gas protection measures may be considered necessary.

There is a potential for PFA in the site to be a source of radon gas. No monitoring of

this has been carried out because the level of radon within the ground does not give a


29

reliable indication of the amount that would be present in buildings constructed on

the site. Studies by the National Radiological Protection Board have indicated that

there is unlikely to be any additional risk to houses built on PFA sites. Nevertheless,

by adopting the “precautionary principle”, a basic level of radon protection should be

provided.

6.3 Geotechnical

6.3.1 PFA

Much of the Central Area of the site is underlain by PFA, which is of variable

composition. It may be anticipated that industrial developments (on the PFA) would

need to be wholly piled. Alternatively, ground improvementtechniques may be used

in conjunction with other foundation systems.

Residential development might be possible using raft foundations, although system

piling to the shallow depth necessary may prove to be economic on a large scale.

Ground improvement would be required beneath roads, parking and hardstanding

areas constructed on the PFA.

PFA is classed as being frost susceptible because of its fine grading. National Ash

recommend for road surfaces “…that unstabilised PFA is kept below the top 450mm

of the carriageway surface to avoid any chance of frost heave.” This should also be

considered for house foundations and a minimum of 450mm cover should be used.

The PFA can be suitable for a founding formation for roads across the site. It may be

possible to reduce the amount of imported material for use as sub-base and capping

by using lime and or cement stabilisation of the PFA.

6.3.2 Gravel abstraction

The gravel was not abstracted from the whole of the site, in particular close to the

railway, the A38, along the line of a former conveyor and other possible ‘islands’ and

ribs of gravel that separated the quarries remain. Structures on shallow foundations

should not be located across these boundaries between PFA and natural ground.

6.3.3 Railway

The Birmingham to Derby railway passes through the site, development within the

railway easement should be done only in consultation with the appropriate authority

6.3.4 Groundwater

Groundwater is present close to ground surface and ground investigation trial pits

were prone to collapse. Accordingly, excavations for the development may require

extensive shoring and/or dewatering. Heavy groundwater inflows were encountered,

particularly in the sands and gravels.

6.3.5 Foundations, excavations and obstructions

The Mercia Mudstone and natural Sand and Gravels are likely to provide a suitable

medium for the founding of structures on the site.


30

Buried obstructions and in particular disused PFA slurry pipes are likely to be

present across the site. Such structures will need to be removed or stabilised (as

needed), depending on their condition, location and depth.

Excavations in PFA should be carried out carefully and measures taken to prevent

dusting by, for example, spraying with water. Any PFA transported off site should be

in a covered vehicle. If stockpiling of PFA is necessary then measures should be put

in place both to restrict run-off erosion and to prevent the surface from drying out

and causing a dust hazard. This may also include the provision of permeable fencing

and dust monitoring.

6.3.6 Liquefaction

In the northern and central part of the site, the PFA had a layered structure and was

strongest within the top 2.0 – 2.5m below which it was a very loose material. South of

this, the PFA was more homogenous and had a firm 1.0m ‘crust’. The nature of the

PFA indicates that there is some potential for loss of bearing strength during a

seismic event; however, an analysis of the liquefaction potential of the PFA at the site

carried out with reference to the Youd and Idriss (1997), BRE publication 210 and

Roger Musson (2002) has shown the probability of liquefaction occurring at the site

(in its current condition) is less than 1 in 10000 per year.

6.3.7 Concrete class

Testing of the Sand and Gravel has indicated that ACEC class AC-2 concrete should

be used for the design of concrete in contact with the Sand and Gravel. However

ACEC class AC-1 concrete would be appropriate for concrete in contact with the PFA.

6.4 Summary

It is expected that the various constraints in the site that have been identified above

can be remediated using established engineering techniques in order that the site can

be made suitable for the proposed development.


Doc no: R.12223 Version: Draft Date: January / 04 / 2011 Project code: PJF085 Filename: 12354 Planning Statement Branston West

final issue 5.7.11.doc

31

7 References

CIRIA Report 143, 1995. Clayton CRI. The Standard Penetration Test (SPT): Methods

and Use. CIRIA, London.

CIRIA C570, 2001. Chandler RJ and Forster A. Engineering in Mercia mudstone.

CIRIA, London.

WS Atkins, October 1990. Branston Development, Burton-on-Trent, Areas 8a and 8b,

Preliminary Site Assessment, Geotechnical Interpretation. Ref U2171/GEO 88233/003/

OCT 90.

W S Atkins, November 2000. Branston Development Prelinary Site Assessment, for St

Modwen Developments Ltd. Ref 83/AF0031/MAS

Coal Authority, August 2002. Coal Mining Report, Branston, Staffordshire. Ref

351434-02

Farebrother and Partners, January 1992. Report on proposed excavations in fly ash at

Branston, Burton on Trent, for St Modwen Developments Ltd. Ref RJP/JCR/7820

Geotechnics Ltd, December 1990. Phase II Branston Development, for Branston

Development Partnership. Ref 90 6505

Halcrow Group Ltd, August 2002. Branston Properties, Branston, Phase 1 Geo-

Environmental Audit.

Halcrow Group Ltd, February 2003. Miller Homes and St Modwen Developments

Ltd, Branston Residential, Phase 2 Geo-Environmental Audit.

Halcrow Group Ltd, July 2003. East Staffordshire Borough Council, Land South of

Branston Zones 2 & 3, Phase 2 Geo-Environmental Audit

Ian Farmer Associates, March 2003. St Modwen Developments Ltd, Branston Zone 1,

Factual Ground Investigation, Final Report No. 2375.

Ian Farmer Associates, June 2003. East Staffordshire Borough Council, Branston

Zones 2 & 3, Factual Ground Investigation, Final Report No. 2478.

Landmark Information Group, August 2002. Envirocheck Report on Branston, for

Branston Properties. Ref 159184-1-1

Landmark Information Group, May 2011. Envirocheck Report. Site at Burton upon

Trent Staffordshire. Ref 34725405_1_1.

Stevenson IP and Mitchell GH, 1955. Geology of the Country between Burton upon

Trent, Rugeley and Uttoxeter, Memoir for 1:50 000 geological sheet 140 (England and

Wales). HMSO.




32

8 Figures

Figure 1: Location plan

Figure 2: Former Development Zones

Branston West, Staffordshire

Figure 1 – Site Location & Boundary Plan

Contains Ordnance Survey data © Crown copyright and database right 2011

Drawn by AGRL Date: 31/05/11 Checked by Date: Authorised by Date:

Drawing Scale at A4: NTS File Name: Figure 1-Site Location & Boundary Plan

SITE LOCATION &

BOUNDARY PLAN

Drawing No.

Figure 1 Revision -

N

Site

Drawn by SKT Date: 31/05/11 Checked by Date: Authorised by Date:

Drawing Scale at A3: NTS File Name: Figure 2 –Former Development Zones

FORMER DEVELOPMENT ZONES

Drawing No.

Figure 2 Revision -


Appendix A

Halcrow Group Ltd Phase 1 Geo-Environmental Audit, August 2002


Appendix A: Halcrow Group Ltd Phase 1 Geo-Environmental Audit, August 2002


Appendix B

Halcrow Group Ltd Phase 2 Geo-Environmental Audit, February 2003




36

Appendix B: Halcrow Group Ltd Phase 2 Geo-Environmental Audit, February 2003


Appendix C

Ian Farmer Associates, Factual Ground Investigation Final Report (2375), March 2003


Appendix C: Ian Farmer Associates, Factual Ground Investigation Final Report (2375), March 2003


Appendix D

Ian Farmer Associates, Factual Ground Investigation Final Report (2478), June 2003




40

Appendix D: Ian Farmer Associates, Factual Ground Investigation Final Report (2478), June 2003


Appendix E

Halcrow Group Ltd Phase 2 Geo-Environmental Audit, July 2003


Appendix E: Halcrow Group Ltd Phase 2 Geo-Environmental Audit, July 2003


Appendix F

Landmark Report, May 2011


Appendix F: Landmark Report, May 2011

Documents

Geo-environmental Planning Statement - East Staffordshire Application... · 2011-11-02 · Geo-environmental Planning Statement, Branston West . 4 . 1 Introduction . This document