WHITEMOSS LANDFILL LIMITED
Whitemoss Landfill Site, Skelmersdale, Lancashire
Materials Suitability Report
November 2016
Wardell Armstrong
2 The Avenue, Leigh, Greater Manchester, WN7 1ES, United Kingdom
Telephone: +44 (0)1942 260101 Facsimile: www.wardell-armstrong.com
DATE ISSUED:
November 2016
JOB NUMBER:
LE12781
REPORT NUMBER:
001
WHITEMOSS LANDFILL LIMITED
Whitemoss Landfill Limited, Skelmersdale, Lancashire
Report on the Suitability of On Site Materials for use in the Construction of Landfill
Cell Phase Ai and Associated Works
November 2016
PREPARED BY:
Josh Perry
Geologist
Andy Belton
Associate Director
APPROVED BY:
Julian Spears
Technical Director
This report has been prepared by Wardell Armstrong LLP with all reasonable skill, care and diligence, within the terms of the Contract
with the Client. The report is confidential to the Client and Wardell Armstrong LLP accepts no responsibility of whatever nature to third
parties to whom this report may be made known.
No part of this document may be reproduced without the prior written approval of Wardell Armstrong LLP.
Wardell Armstrong is the trading name of Wardell Armstrong LLP, Registered in England No. OC307138.
Registered office: Sir Henry Doulton House, Forge Lane, Etruria, Stoke-on-Trent, ST1 5BD, United Kingdom
UK Offices: Stoke-on-Trent, Birmingham, Cardiff, Carlisle, Edinburgh, Greater Manchester, London, Newcastle upon Tyne,
Penryn, Sheffield, Truro, West Bromwich. International Offices: Almaty, Moscow
ENERGY AND CLIMATE CHANGE
ENVIRONMENT AND SUSTAINABILITY
INFRASTRUCTURE AND UTILITIES
LAND AND PROPERTY
MINING AND MINERAL PROCESSING
MINERAL ESTATES AND QUARRYING
WASTE RESOURCE MANAGEMENT
WHITEMOSS LANDFILL LIMITED
Whitemoss Landfill Site, Skelmersdale, Lancashire
Material Suitability Report
CONTENTS
1
INTRODUCTION .................................................................................................................. 1
2
PREVIOUS SITE INVESTIGATIONS ........................................................................................ 3
3
MATERIAL SUITABILITY ....................................................................................................... 4
4
SAMPLING COLLECTION ..................................................................................................... 5
5
CLAY TESTING UNDERTAKEN .............................................................................................. 6
6
SAND TESTING UNDERTAKEN ............................................................................................. 9
7
DETERMINATION OF ACCEPTABLE CRITERIA FOR MATERIALS USED IN MINERAL LINING
WORKS .............................................................................................................................. 10
8
SUMMARY AND CONCLUSIONS ........................................................................................ 14
TABLES
Table 2.1 Summary of Previous Site Investigation Results ........................................................ 3
Table 5.1 Summary of Testing for Clay Liner Properties ........................................................... 6
Table 5.2 Rammer Test Results (2.5kg and 4.5kg) ..................................................................... 7
Table 5.3 Hand Shear Vane Tests............................................................................................... 8
Table 6.1 PSD and Permeability Testing Results ........................................................................ 9
Table 7.1 Permeability Testing Results .................................................................................... 11
APPENDICES
Appendix 1
Photographic Record of Trial Pits
Appendix 2
Laboratory Test Results from the Construction of the Mineral Liner, Phase Ai
DRAWINGS
LE12781/001 Site Location
LE12781/036
LE12781/001
November 2016
Materials
Suitability
Trial
Pit
locations
WHITEMOSS LANDFILL LIMITED
Whitemoss Landfill Site, Skelmersdale, Lancashire
Material Suitability Report
1
INTRODUCTION
1.1
Whitemoss Landfill Site is located on White Moss Road South in Skelmersdale,
Lancashire to the south of the M58 motorway adjacent to Junction 4. The location of
the site is shown on Drawing Number LE12781-001.
1.2
Site Address: Whitemoss Landfill Site, Whitemoss Road South, Skelmersdale,
Lancashire, WN8 9TH.
1.3
Whitemoss Landfill Limited operates Whitemoss landfill at White Moss Road South,
Skelmersdale under Environmental Permit number DP/3639LM/V005.
1.4
An Application for a Development Consent Order under the Planning Act 2008 for
Construction of New Landfill Void to the west of the Existing Landfill Site for the
disposal of Hazardous Waste was submitted in December 2013. The DCO application
was granted on 21 May 2015.
1.5
This report relates to the suitability of the on-site materials (clay and sand) in the
construction of landfill cell Phase Ai. The location of Phase Ai, the source of the
proposed materials is shown on Drawing Number LE12781/036.
1.6
The following reports, appertaining to design considerations for these cells, have
previously been submitted to the Environment Agency by Wardell Armstrong:
1. Report on the Suitability of the Indigenous Clay Source for use in Lining works at
White Moss Road South Landfill Site, Skelmersdale Incorporating Procedures for
Compaction and Post Placement Quality Control Testing Prepared for J Routledge
and Sons (Liverpool) Limited December 1997;
2. 1995 Source Evaluation, May 1995 presented in Cell 1.2 and 1.3 CQA Report Sept
1995.
3. Stability Risk Assessment June 2003 J Routledge and Sons Ltd. Whitemoss Road
South Landfill Site;
4. Validation Report on the Construction of Cell 3D, Whitemoss Landfill Site, J
Routledge and Sons Ltd May 2004; and
5. Permit Application including the Hydrogeological Risk Assessment (HRA) and
Stability Risk Assessment (SRA) for the proposed works.
1.7
Laboratory testing has been undertaken to assess the suitability of clay materials for
use as a landfill mineral liner and sand for use as a protection medium to the
geomembrane.
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Whitemoss Landfill Site, Skelmersdale, Lancashire
Material Suitability Report
1.8
In the preparation of the report, particular reference has been made to the guidance
contained in LFE4 – Earthworks in landfill engineering. Design construction and
quality assurance of earthworks in landfill engineering Published by the Environment
Agency.
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WHITEMOSS LANDFILL LIMITED
Whitemoss Landfill Site, Skelmersdale, Lancashire
Material Suitability Report
2
PREVIOUS SITE INVESTIGATIONS
2.1
There have been three phases site of site investigation works relating to the
materials properties of the clay at the site. The results of these investigations is
summarised in Table 2.1, below:
Table 2.1 Summary of Previous Site Investigation Results
Test
Natural Moisture Content (%)
Liquid Limit (%)
Plastic Limit (%)
Plasticity Index (%)
Particle Density (Mg/m3)
Clay
PSD (%
Silt
Passing)
Sand
Optimum
Moisture
Content
Compaction
(OMC) (%)
(2.5g Ramer)
MDD
(mg/m3)
Permeability (m/s)
Source Evaluation
(1995)*1
13-14
28-30
13
15-17
2.61-2.64
18-23
33-39
34-37
Clay Suitability
Report (1997)*2
14-18
29-31
13-15
15-16
2.67-2.68
12-23
27-44
33-45
Cell 3D Report
(2004)*3
9.4-15.0
26-34
13-17
11-20
2.67-2.70
19-26
31-38
29-41
7.6-8.3
11-12
11-13
2.12-2.14
1.93-2.01
1.96-2.03
8.7x10-10 - 6.9x10-11
1x10-10 - 2.9x10-11
1.1x10-10 - 1.9x10-11
Note:
*1 1995 Source Evaluation, May 1995 presented in Cells 1.2 and 1.3 CQA Report Sept 1995.
*2 Report on the Suitability of the Indigenous Clay Source for use in Lining works at White Moss Road South Landfill
Site, Skelmerdale Incorporating Procedures for Compaction and Post Placement Quality Control Testing Prepared for J
Routledge and Sons (Liverpool) Limited December 1997.
*3 Validation Report on the Construction of Cell 3D, Whitemoss Landfill Site, J Routledge and Sons Ltd May 2004.
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WHITEMOSS LANDFILL LIMITED
Whitemoss Landfill Site, Skelmersdale, Lancashire
Material Suitability Report
3
MATERIAL SUITABILITY
CRITERIA FOR MINERAL LINING
3.1
To meet guidance regulations, the clay mineral liner must be subjected to testing
both before and after compaction to ensure it meets the minimum requirements.
Although the minimum requirements put forward for a mineral lining vary, the
following requirements are those detailed in Table 4: Typical clay liner or cap
properties contained within LFE4 – Earthworks in landfill engineering. Design
construction and quality assurance of earthworks in landfill engineering
3.2
These requirements can be summarised as follows, they are generally recognised as
being standard and the parameters which will be met by all materials incorporated
within the mineral liner;

The material should be capable of being compacted to achieve a permeability of
equal to or less than 1.0 x 10-9m/s;

The material should be capable of being compacted to an undrained shear
strength equal to or greater than 50kPa (50kNm2);

Plasticity index should be between 10 and 65 (slightly to highly plastic);

Liquid limit should be less than or equal to 90%;

Percentage fines (less than 63µm) be greater than or equal to 20%;

Clay content (less than 2µm) be greater than 8%;

Percentage gravel (greater than 5mm) should be less than 30%;

Maximum particle size should not exceed 125 millimetres; and

Material should be chemically stable and suitable.
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WHITEMOSS LANDFILL LIMITED
Whitemoss Landfill Site, Skelmersdale, Lancashire
Material Suitability Report
4
SAMPLING COLLECTION
4.1
Clay samples for laboratory testing were taken from trial pits and sand samples were
taken from on-site stockpiles, the locations of these areas is shown on Drawing
Number LE12781/036.
4.2
The 6no clay samples were collected by an experienced geotechnical engineer (Ian
Clarke) from Wardell Armstrong on 15 September 2016.
4.3
The 2no sand samples were collected by an experienced geotechnical engineer
(Andrew Belton) from Wardell Armstrong on 28 September 2016.
4.4
All samples were collected on the day of sampling by a courier from the appointed
soil testing laboratory, namely Professional Soil Laboratory (PSL) based in Doncaster.
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WHITEMOSS LANDFILL LIMITED
Whitemoss Landfill Site, Skelmersdale, Lancashire
Material Suitability Report
5
CLAY TESTING UNDERTAKEN
5.1
Laboratory testing on the clay samples, obtained from trial pitting, was instructed by
Wardell Armstrong and the testing was undertaken in accordance with BS 1377
“British Standard Methods of Tests for Soils for Civil Engineering Purposes, 1990”.
5.2
The samples were tested to characterise the clay materials, understand the
compaction properties and review the resultant permeabilities of the compacted
clay materials.
5.3
5.4
The following testing was performed on the samples:

Index properties (BS 1377: 1990: Part 2: Methods 4.3, 5.3 and 5.4);

Grading (BS 1377: 1990: Part 2: Method 9.2);

Sedimentation (BS 1377: 1990: Part 2: Method 9.4);

Moisture content (BS 1377: 1990: Part 2: Method 3.2);
The results of these tests are summarised in Table 5.1 below:
Trial Pit
Number
(depth)
TP1 (4.1)
TP2 (4.6)
TP3 (3.9)
TP4 (4.1)
TP5 (4.9)
Minimum
Maximum
Mean
5.5
Table 5.1 Summary of Testing for Clay Liner Properties
Fines
Clay
Gravel
Plasticity Liquid
Content
Content
Content
Index
Limit
(%)
(%)
(%)
14
30
61
30
9
14
29
60
31
9
15
31
65
31
4
15
32
62
34
4
13
29
59
32
9
13
15
14.2
29
32
30.2
59
65
61.4
30
34
31.4
4
9
7
Moisture
Content
(%)
13
13
13
12
12
12
13
12.6
In order to assess that the compaction requirements the following testing was
performed;

2.5kg rammer test (BS 1377: 1990: Part 4: Method 3.3)

4.5kg rammer test (BS 1377: 1990: Part 4: Method 3.5)

Permeability in a Triaxial Cell (BS 1377: 1990: Part 6: Method 6)
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WHITEMOSS LANDFILL LIMITED
Whitemoss Landfill Site, Skelmersdale, Lancashire
Material Suitability Report
5.6
The results of the 2.5kg and 4.5kg rammer tests are summarised in Table 5.2 below:
Table 5.2 Rammer Test Results (2.5kg and 4.5kg)
Trial Pit Number (Depth)
Dry Density (Mg/m3)
Moisture Content (%)
2.5kg Rammer Test Results
5.7
TP1 (4.1)
1.94
13.0
TP3 (3.9)
1.90
13.0
TP5 (4.9)
1.87
12.0
Maximum
1.94
12.0
Minimum
1.87
13.0
Mean
1.90
12.7
TP1 (4.1)
4.5kg Rammer Test Results
2.04
10
The full data sets from the three 2.5kg rammer tests were then averaged to provide
a single data set from which the Acceptability Envelope for the works could be
generated. The Acceptability Envelope is discussed more fully in Section 7 below.
5.8
In addition to the 2.5kg rammer testing a hand shear vane test was performed on
each of the recompacted samples at five moisture values. The results of these tests
are contained in Table 5.3 below.
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WHITEMOSS LANDFILL LIMITED
Whitemoss Landfill Site, Skelmersdale, Lancashire
Material Suitability Report
Table 5.3 Hand Shear Vane Tests
Trial Pit Number (Depth)
Moisture Content (%)
Shear Strength (Kpa)
TP3 (3.9)
TP3 (3.9)
TP3 (3.9)
TP3 (3.9)
TP3 (3.9)
7
10
13
16
19
>148
>148
135
95
60
TP1 (4.1)
TP1 (4.1)
TP1 (4.1)
TP1 (4.1)
TP1 (4.1)
7
10
13
15
18
>148
>148
130
98
72
TP1 (4.1)1
TP1 (4.1)1
TP1 (4.1)1
TP1 (4.1)1
TP1 (4.1)1
5
7
10
13
15
>148
>148
>148
135
102
TP5 (4.9)
TP5 (4.9)
TP5 (4.9)
TP5 (4.9)
TP5 (4.9)
6
9
12
15
18
>148
>148
133
88
70
Note: (1) Results from the 4.5kg rammer test
5.9
The results from Table 5.3 were then used to instruct the laboratory as to the
moisture content and shear strength values to use in the Triaxial Permeability test.
The values used and the test results are discussed more fully in Section 7 below.
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WHITEMOSS LANDFILL LIMITED
Whitemoss Landfill Site, Skelmersdale, Lancashire
Material Suitability Report
6
SAND TESTING UNDERTAKEN
6.1
Laboratory testing on the sand samples, obtained from the Phase Ai area, was
instructed by Wardell Armstrong and the testing was undertaken in accordance with
BS 1377 “British Standard Methods of Tests for Soils for Civil Engineering Purposes,
1990”.
6.2
6.3
The following testing was performed on the samples to characterise the sand:

Grading (BS 1377: 1990: Part 2: Method 9.2);

Sedimentation (BS 1377: 1990: Part 2: Method 9.4); and

Permeability (BS 1377: 1990: Part 6: Method 6).
The results of these tests are summarised in Table 6.1 below.
Table 6.1 PSD and Permeability Testing Results
Sample 1
Sample 2
Particle Size
Particle Size
Distribution
Distribution
Permeability (m/s)
Permeability (m/s)
Sieve Size Percentage
Sieve Size Percentage
(mm)
Passing (%)
(mm)
Passing (%)
6.3
100
6.3
99
3.35
98
3.35
99
2
96
2
98
1.18
94
1.18
97
0.6
89
0.6
92
-6
0.3
65
2.1x10
0.3
70
1.9x10-6
0.212
37
0.212
43
0.15
20
0.15
27
0.063
13
0.063
18
0.02
8
0.02
11
0.006
5
0.006
7
6.4
Sand from the stockpile was used in a cylinder test. A 200m thick layer of sand was
placed over a 2mm HDPE liner and subjected to a pressure of up to 1177.2tpa (based
on 30m of waste with a density of 1.6Mg/m3). No noticeable deformation was
recorded.
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WHITEMOSS LANDFILL LIMITED
Whitemoss Landfill Site, Skelmersdale, Lancashire
Material Suitability Report
7
DETERMINATION OF ACCEPTABLE CRITERIA FOR MATERIALS USED IN MINERAL
LINING WORKS
7.1
The results of the clay materials testing of samples taken from the trial pits show
that prior to compaction, the clay materials all conform to the criteria contained
within Table 4: Typical clay liner or cap properties contained within LFE4 –
Earthworks in landfill engineering.
7.2
As part of the 2.5kg rammer testing a hand shear vane test was performed on each
of the recompacted samples at five moisture values for each test (the test results are
shown in Table 5.3 above). These values were then plotted in Excel and the trend
line added. The trend line equation was then used to determine the moisture
percentage which gives a shear value of 50kPa. The calculated value of the moisture
content at 50kPa is 21.36%.
This value was then plotted on the Dry
Density/Moisture Content Relationship Graph.
Hand Shear Vane Test Results
170
Shear Strength (kPa)
150
130
y = -7.3219x + 209.7
110
90
70
50
5.00
7.00
9.00
11.00
13.00
15.00
17.00
19.00
21.00
23.00
Moisture Content (%)
MC @ 50kPa
7.3
All TP Results
Linear (All TP Results)
Test results demonstrate that the proposed materials for the mineral liner have
suitable properties for hydraulic conductivity across a range of moisture contents
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WHITEMOSS LANDFILL LIMITED
Whitemoss Landfill Site, Skelmersdale, Lancashire
Material Suitability Report
and dry densities as shown in Table 7.1 below.
Trial Pit Number
(Depth)
TP1
TP2
TP3
TP4
TP5
TP5
Minimum
Maximum
Mean
Table 7.1 Permeability Testing Results
Dry Density
Moisture Content
3
(Mg/m )
(%)
1.99
8
2.02
10
1.85
11
1.86
15
1.92
13
1.98
12
1.85
8
2.02
15
1.925
11.5
Permeability (m/s)
1.4x10-10
1.1x10-10
1.1x10-10
8.4x10-11
1.0x10-10
7.0x10-11
8.4x10-11
7.0x10-10
2.5x10-10
7.4
The particle density (used to calculate the Air Void curves) was taken as 2.65 Mg/m3.
7.5
The 0% and 5% Air Void curves were then plotted onto a Dry Density/Moisture
Content Relationship graph. In line with EA guidance the 0% and 5% air voids line
form the boundaries of the acceptability envelope.
7.6
The other two parameters of the Acceptability Envelope were also plotted namely
the maximum dry density and the 95% Maximum Dry Density line at 1.86 Mg/m3.
7.7
The moisture content value at which a minimum 50kpa strength is achieved was
calculated at 21.36%. As this is considerably higher than the materials optimum
moisture content and outside the proposed acceptability envelope. It is considered
that that ‘as placed’ clay will always be higher than 50kpa and hence the 50kpa
requirement will not affect the acceptability of this material.
7.8
The test values used for the permeability and shear strength testing were also
plotted onto the Acceptability Envelope to demonstrate that the 5% air void line and
the 95% maximum dry density values used were suitable for the Acceptability
envelope.
7.9
With respect to permeability LFE 4 states that a minimum value of 1.0 x 10-9m/s
must be achieved. As can be seen from Table 7.1 above, the permeability values
achieved in testing are an order of magnitude above what is required ranging from a
minimum of 8.4 x 10-11m/s1 to a maximum of 1.0 x 10-10m/s1 with a mean of 2.5 x 1010m/s.
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WHITEMOSS LANDFILL LIMITED
Whitemoss Landfill Site, Skelmersdale, Lancashire
Material Suitability Report
7.10
These tests demonstrate that if clay material excavated from the footprint of Phase
Ai at Whitemoss Landfill are compacted such that the dry density and moisture
content results lie within the Acceptability Envelope a permeability will be achieved
that
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complies
with
the
requirements
of
LFE4.
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WHITEMOSS LANDFILL LIMITED
Whitemoss Landfill Site, Skelmersdale, Lancashire
Report on the Suitability of Material for use as a Mineral Liner in the Construction of Landfill Cell Phase Ai
and Associated Works
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November 2016
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WHITEMOSS LANDFILL LIMITED
Whitemoss Landfill Site, Skelmersdale, Lancashire
Report on the Suitability of Material for use as a Mineral Liner in the
Construction of Landfill Cell Phase Ai and Associated Works
8
SUMMARY AND CONCLUSIONS
8.1
Previous site investigations at Whitemoss Landfill have shown that the site-won clay
conforms to the criteria in Section 4.2 of LFE4 and is suitable for mineral lining
works, the results of this study are comparable to the results of previous
investigations.
8.2
The soils laboratory testing programme has identified that the clay material within
the proposed source area is capable of being compacted to achieve a permeability of
less than or equal to 1 x 10-9m/s and we are fully satisfied that it is suitable for use in
mineral lining works.
8.3
There were no predetermined guidance values for sand materials excavated from
the on-site stockpiles, however testing undertaken by Professional Soils Laboratory
showed that the samples were well graded sand and the cylinder test results showed
no deformation in the geomembrane. Therefore, the sand will be suitable as a
protection layer to the geomembrane at a thickness of 150mm.
8.4
In accordance with LFE4 a field trial will be undertaken at the start of the
construction works. This will confirm construction methods and proposed plant are
suitable to achieve conformance with the specification.
8.5
Finally, the results of the laboratory testing discussed in this report will be used to
inform the moisture content of the clay used in the field trial. Based on the proposed
Acceptability Envelope above, the clay used should be placed with a moisture
content in the range of 11%-16% (OMC-1% - OMC+4%) in order to meet the
specification and requirements of LFE4
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WHITEMOSS LANDFILL LIMITED
Whitemoss Landfill Site, Skelmersdale, Lancashire
Report on the Suitability of Material for use as a Mineral Liner in the
Construction of Landfill Cell Phase Ai and Associated Works
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