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Geo-environmental Planning Statement
Land South of Branston, Burton-upon-Trent
Branston West
St Modwen Developments Ltd
July 2011
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
Geo-environmental Planning Statement
Branston West
St Modwen Developments Ltd
July 2011
Geo-environmental Planning Statement, Branston West
Document history
Geo-environmental Planning Statement
Branston West
St Modwen Developments Ltd
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
Geo-environmental Planning Statement, Branston West
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
Geo-environmental Planning Statement, Branston West
3
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
Geo-environmental Planning Statement, Branston West
4
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.
Geo-environmental Planning Statement, Branston West
5
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.
Geo-environmental Planning Statement, Branston West
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
Geo-environmental Planning Statement, Branston West
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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
Geo-environmental Planning Statement, Branston West
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.
Geo-environmental Planning Statement, Branston West
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.
Geo-environmental Planning Statement, Branston West
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
Geo-environmental Planning Statement, Branston West
11
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
Geo-environmental Planning Statement, Branston West
12
• Buildings (buried concrete, services)
• Secondary A Aquifer within the sand and gravel deposits
• Tatenhill Brook and streams in the site
• River Trent
Geo-environmental Planning Statement, Branston West
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
Geo-environmental Planning Statement, Branston West
14
(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)
(a) Northern part of the site (former Zone 1)
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.
Geo-environmental Planning Statement, Branston West
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.
(b) Central and southern parts of the site (former Zones 2 and 3)
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
(a) Northern part of the site (former Zone 1)
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.
(b) Central and southern parts of the site (former Zones 2 and 3)
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.
Geo-environmental Planning Statement, Branston West
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
(a) Northern part of the site (former Zone 1)
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.
(b) Central and southern parts of the site (former Zones 2 and 3)
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
Geo-environmental Planning Statement, Branston West
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
(a) Northern part of the site (former Zone 1)
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.
(b) Central and southern parts of the site (former Zones 2 and 3)
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%).
Geo-environmental Planning Statement, Branston West
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.
Geo-environmental Planning Statement, Branston West
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.
Geo-environmental Planning Statement, Branston West
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
Determinand Threshold level * (µg/l)
Highest level (times
threshold)
No/ of samples above threshold level / no. tested
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
* EA denotes EA EQS, WS denotes Water Supply (Water Quality) Regs 2000 and 1989 for Phenol and
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)
Highest level (times
threshold)
No of samples
above threshold
level
Geo-environmental Planning Statement, Branston West
21
Determinand Threshold level *
(mg/kg)
Highest level (times
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
Determinand Threshold level * (µg/l)
Highest level (times
threshold)
No/ of samples above threshold level / no. tested
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
Geo-environmental Planning Statement, Branston West
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
Determinand Threshold level *
(mg/kg)
Highest level (times
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
Determinand Threshold level * (µg/l)
Highest level (times
threshold)
No/ of samples above threshold level / no. tested
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
* EA denotes EA EQS, WS denotes Water Supply (Water Quality) Regs 2000 and 1989 for Phenol and
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
Geo-environmental Planning Statement, Branston West
23
Determinand Threshold level *
(mg/kg)
Highest level (times
threshold)
No of samples
above threshold
level
Boron 3 ICRCL 11 (x 3.7) 1/2
* CLEA denotes Environment Agency guidelines for residential with plant uptake, ICRCL denotes ICRCL
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
Determinand Threshold level * (µg/l)
Highest level (times
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
* EA denotes EA EQS, WS denotes Water Supply (Water Quality) Regs 2000 and 1989 for Phenol and
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
Geo-environmental Planning Statement, Branston West
24
Determinand Threshold level *
(mg/kg)
Highest level (times
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
* CLEA denotes Environment Agency guidelines for residential with plant uptake, ICRCL denotes ICRCL
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
(a) Northern part of the site (former Zone 1)
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.
Geo-environmental Planning Statement, Branston West
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.
(b) Central and southern parts of the site (former Zones 2 and 3)
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)
Highest level (times
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
Geo-environmental Planning Statement, Branston West
26
Determinand Threshold
level * (µg/l unless stated)
Highest level (times
threshold)
No of samples above threshold level/ no tested
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
* EA denotes EA EQS, WS denotes Water Supply (Water Quality) Regs 2000 and 1989 for Phenol and
Potassium
Table 5.11 Summary of elevated chemical results on groundwater sampled on 14 May 2003
Determinand Threshold
level * (µg/l unless stated)
Highest level (times
threshold)
No of samples above threshold level/ no tested
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
* EA denotes EA EQS, WS denotes Water Supply (Water Quality) Regs 2000 and 1989 for Phenol and
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
Determinand Threshold
level * (µg/l unless stated)
Highest level (times
threshold)
No of samples above threshold level/ no tested
Arsenic 10 EA 19 (x 1.9) 1/5
Geo-environmental Planning Statement, Branston West
27
Determinand Threshold
level * (µg/l unless stated)
Highest level (times
threshold)
No of samples above threshold level/ no tested
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
Geo-environmental Planning Statement, Branston West
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
Geo-environmental Planning Statement, Branston West
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.
Geo-environmental Planning Statement, Branston West
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.
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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.
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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 -
Geo-environmental Planning Statement, Branston West
Appendix A
Halcrow Group Ltd Phase 1 Geo-Environmental Audit, August 2002
Geo-environmental Planning Statement, Branston West
Appendix A: Halcrow Group Ltd Phase 1 Geo-Environmental Audit, August 2002
Geo-environmental Planning Statement, Branston West
Appendix B
Halcrow Group Ltd Phase 2 Geo-Environmental Audit, February 2003
Geo-environmental Planning Statement, Branston West
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Appendix B: Halcrow Group Ltd Phase 2 Geo-Environmental Audit, February 2003
Geo-environmental Planning Statement, Branston West
Appendix C
Ian Farmer Associates, Factual Ground Investigation Final Report (2375), March 2003
Geo-environmental Planning Statement, Branston West
Appendix C: Ian Farmer Associates, Factual Ground Investigation Final Report (2375), March 2003
Geo-environmental Planning Statement, Branston West
Appendix D
Ian Farmer Associates, Factual Ground Investigation Final Report (2478), June 2003
Geo-environmental Planning Statement, Branston West
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Appendix D: Ian Farmer Associates, Factual Ground Investigation Final Report (2478), June 2003
Geo-environmental Planning Statement, Branston West
Appendix E
Halcrow Group Ltd Phase 2 Geo-Environmental Audit, July 2003
Geo-environmental Planning Statement, Branston West
Appendix E: Halcrow Group Ltd Phase 2 Geo-Environmental Audit, July 2003
Geo-environmental Planning Statement, Branston West
Appendix F
Landmark Report, May 2011
Geo-environmental Planning Statement, Branston West
Appendix F: Landmark Report, May 2011