Post on 07-Mar-2021
Appendix 3
Soiltechnics Soil Permeability Test Report
Soiltechnics Limited
Registered in England 2680759
Registered office: Cedar Barn, NN6 9PY
Cedar Barn
White Lodge
Walgrave
Northamptonshire
NN6 9PY
t: 01604 781877
f: 01604 781007
e: mail@soiltechnics.net
w: www.soiltechnics.net
Dear Emma,
Re: Hall Lane, Kettering
Further to your instructions, we confirm completion of investigations at the above site and can now provide
the following report.
Objectives
We confirm our brief was to carry out investigations to determine the infiltration rate of the soils within the
grounds of the former Our Lady’s Convent School. The scope of fieldwork activities and position of exploratory
points were defined by your good selves.
This report has been prepared for the sole benefit of our above named instructing client, but this report, and
its contents, remains the property of Soiltechnics Limited until payment in full of our invoices in connection
with production of this report.
Brief description of the site and geology of the area
The site lies is a predominantly residential area of Kettering, Northamptonshire and is currently occupied by a
number of buildings; formerly used as a school and convent, surrounded by extensive overgrown gardens
including an orchard and pond, and former playing fields. The site slopes to the east by approximately 12m
across the site.
Inspection of the geological map of the area indicates the local topography of the area is formed in deposits of
Northampton Sand Formation (clay, silt, sand and gravel) overlying Whitby Mudstone Formation (formerly
Upper Lias Clay) (mudstone) at depth.
Emma Skelley
Wardell Armstrong LLP
Sir Henry Doulton House
Forge Lane
Etruria
Stoke on Trent
ST1 5BD
Date:
Your Ref:
Our Ref:
27.02.2013
L-STK2404U-002
STK2404U-L002 Page 2 of 3 27th
February 2013
Fieldwork
Fieldwork was carried out on 27th
February 2013 and comprised the formation of four trial pits. Trial pits
TP101 to TP104 were excavated to a maximum depth of 1.56m using a rubber tyred excavator. Logging was
carried out as trial pit excavations proceeded but were not entered at depths exceeding 1.2m. The excavations
were backfilled with excavated material compacted using the back of the excavator bucket. Whilst we
attempted to reinstate the excavation to its original condition some short-term settlement of the backfilling
materials may occur. A Geotechnical Engineer supervised the excavations. The positions of the exploratory
points are recorded on Drawing 101 (attached).
Soil infiltration tests were carried out in trial pits TP101 to TP104 at depths of between 0.84m and 1.56m. The
infiltration tests were carried out following the procedures described in the Building Research Establishment
(BRE) Digest 365 (2007) “Soakaway Design”. The position of previously undertaken exploratory excavations
and recent infiltration tests are shown on Drawing 101, appended.
Ground conditions encountered
The trial pit excavations encountered a similar profile of soils considered to be Topsoil, Northampton Sand
Formation overlying Whitby Mudstone Formation.
Topsoil consisting of medium dense dark brown sand and stiff orange brown clays with varying proportions of
gravel including sandstone and quartzite and extended to a maximum depth of 0.5m.
Northampton Sand Formation consisting of medium and high strength light brown orange sandy clay and
extended to a maximum depth of 1.3m.
Whitby Mudstone Formation generally comprised high strength light brown mottle light grey becoming grey
with depth slightly silty clay and extended beyond the termination depth of the trial pits.
No groundwater inflows were observed in any of the exploratory excavations.
Infiltration Potential
Infiltration testing was attempted to be undertaken following procedures described in BRE Digest 365
Soakaway design 2007. Water either failed to dissipated or dissipated insufficiently to derive an accurate
infiltration rate. On this basis we are of the opinion that the soils are effectively impermeable. Records of
infiltration testing undertaken are appended.
STK2404U-L002 Page 3 of 3 27th
February 2013
We trust this report provides you with the information you require, however, should you have any queries
please do not hesitate to contact us.
Yours sincerely,
Ross Carrington BSc (Hons), MSc, CSci, AIEMA
Geo-environmental engineer for Soiltechnics Limited
Reviewed by
Dr Matthew Hooper B.Sc. (Hons)., M.Sc., Ph.D., M.I.Env.Sc.
Senior Geo-environmental Engineer for Soiltechnics Limited
Encs Drawing 101 – Existing site layout and position of exploratory points
Trial pit / infiltration records
Standard Key to trial pit records
Key to legends (extract from BS5930 table 11)
Soils Sedimentary rocks
Topsoil Chalk
Made ground Limestone
Boulders & Cobbles Sandstone
Gravel Siltstone
Sand Mudstone
Silt Shale
Clay Coal
Peat/Organic clays Conglomerate
Composite soil types are signified by combined symbols.
Key to ‘test result’ columns
Column header Explanation
Type and depth Records depth that the test was carried out ie at 2.1m or between 2.1 and 2.55m
Result P – Pocket penetrometer result
V – Hand held shear vane result (KN/m2)
Carried out on
undisturbed samples or
in sides /base of trial pit
Key to ’sampling’ columns
Column header Explanation
From (m)
To (m)
Records depth of sampling
Type D – Disturbed sample
B – Bulk disturbed sample
J – Disturbed sample placed in sealed amber jar
W – Water sample
CBR Undisturbed sample in mould (California Bearing Ratio)
Water observations
Described at foot of log
Our Lady’s Convent School Hall Lane, Kettering
Title
Soil infiltration test (following principles of the Building
Research Establishment Digest 365 2007)
Co-ordinates
-
Trial pit number
TP101
Ground level
N/A
Date of excavation
27.02.2013
Groundwater observations
No groundwater encountered
Method of excavation
JCB 3CX
Location plan on drawing number
101
Report ref: STK2404U-002 Revision: 0
February 2013
Cycle number
1
Trial pit dimensions (width x length)
0.6m x 1.4m
Soil description and strata: Plot showing time against depth to water: Test observations:
0.870
0.870
0.870
0.865
0.850
0.840
TIME
(mins)
DEPTH TO
WATER (m)
Calculations:
Slight rise in water level over 252 minutes; soils considered effectively impermeable.
Brown sandy slightly gravelly clayey TOPSOIL. Gravel
consists of sandstone and quartzite.
Medium strength orange brown sandy CLAY.
(NORTHAMPTON SAND FORMATION)
High strength light grey mottled grey CLAY.
(WHITBY MUDSTONE FORMATION)
TRIAL PIT TERMINATED AT 1.21m DEPTH
Notes:
1. Trial pit side remained upright and stable
0.0
0.2
0.7
1.21
DESCRIPTION LEGEND DEPTH
(m)
0
16
60
92
143
252
Our Lady’s Convent School Hall Lane, Kettering
Title
Soil infiltration test (following principles of the Building
Research Establishment Digest 365 2007)
Co-ordinates
-
Trial pit number
TP102
Ground level
N/A
Date of excavation
27.02.2013
Groundwater observations
No groundwater encountered
Method of excavation
JCB 3CX
Location plan on drawing number
101
Report ref: STK2404U-002 Revision: 0
February 2013
Cycle number
1
Trial pit dimensions (width x length)
0.6m x 1.4m
Soil description and strata: Plot showing time against depth to water: Test observations:
0.800
0.800
0.800
0.795
0.795
0.795
TIME
(mins)
DEPTH TO
WATER (m)
Calculations:
Slight rise in water level over 254 minutes; soils considered effectively impermeable.
Brown sandy clayey TOPSOIL.
Medium strength orange brown sandy CLAY.
(NORTHAMPTON SAND FORMATION)
High strength orange slightly sandy CLAY.
(NORTHAMPTON SAND FORMATION)
Light brown mottled light grey CLAY.
(WHITBY MUDSTONE FORMATION)
TRIAL PIT TERMINATED AT 1.07m DEPTH
Notes:
1. Trial pit side remained upright and stable
0.0
0.15
0.45
1.0
1.07
DESCRIPTION LEGEND DEPTH
(m)
0
28
69
101
152
254
Our Lady’s Convent School Hall Lane, Kettering
Title
Soil infiltration test (following principles of the Building
Research Establishment Digest 365 2007)
Co-ordinates
-
Trial pit number
TP103
Ground level
N/A
Date of excavation
27.02.2013
Groundwater observations
No groundwater encountered
Method of excavation
JCB 3CX
Location plan on drawing number
101
Report ref: STK2404U-002 Revision: 0
February 2013
Cycle number
1
Trial pit dimensions (width x length)
0.6m x 1.4m
Soil description and strata: Plot showing time against depth to water: Test observations:
1.110
1.160
1.160
1.155
1.155
1.150
TIME
(mins)
DEPTH TO
WATER (m)
Calculations:
Initial infiltration into unsaturated soils then slight rise in water level over 254 minutes; soils considered effectively impermeable.
Brown sandy slightly gravelly clayey TOPSOIL. Gravel
consists of sandstone and quartzite.
Medium strength orange light brown slightly sandy CLAY.
(NORTHAMPTON SAND FORMATION)
High strength grey occasionally mottled light brown
CLAY.
(WHITBY MUDSTONE FORMATION)
TRIAL PIT TERMINATED AT 1.56m DEPTH
Notes:
1. Trial pit side remained upright and stable
0.0
0.5
1.3
1.56
DESCRIPTION LEGEND DEPTH
(m)
0
35
75
107
158
254
Our Lady’s Convent School Hall Lane, Kettering
Title
Soil infiltration test (following principles of the Building
Research Establishment Digest 365 2007)
Co-ordinates
-
Trial pit number
TP104
Ground level
N/A
Date of excavation
27.02.2013
Groundwater observations
No groundwater encountered
Method of excavation
JCB 3CX
Location plan on drawing number
101
Report ref: STK2404U-002 Revision: 0
February 2013
Cycle number
1
Trial pit dimensions (width x length)
0.6m x 1.4m
Soil description and strata: Plot showing time against depth to water: Test observations:
0.840
0.870
0.880
0.890
TIME
(mins)
DEPTH TO
WATER (m)
Calculations:
Slight fall in water level over 111 minutes; insufficient data to calculate an infiltration rate.
Brown sandy clayey TOPSOIL.
Medium strength orange sandy CLAY.
(NORTHAMPTON SAND FORMATION)
TRIAL PIT TERMINATED AT 1.06m DEPTH
Notes:
1. Trial pit side remained upright and stable
0.0
0.3
1.06
DESCRIPTION LEGEND DEPTH
(m)
0
39
79
111
Our Lady’s Convent School Hall Lane, Kettering
Title
Soil infiltration test (following principles of the Building
Research Establishment Digest 365 2007)
Co-ordinates
-
Trial pit number
TP104
Ground level
N/A
Date of excavation
27.02.2013
Groundwater observations
No groundwater encountered
Method of excavation
JCB 3CX
Location plan on drawing number
101
Report ref: STK2404U-002 Revision: 0
February 2013
Cycle number
2
Trial pit dimensions (width x length)
0.6m x 1.4m
Soil description and strata: Plot showing time against depth to water: Test observations:
0.710
0.720
0.745
0.760
0.770
0.790
0.795
0.800
TIME
(mins)
DEPTH TO
WATER (m)
Calculations:
Slight fall in water level over 149 minutes; insufficient data to calculate an infiltration rate.
Brown sandy clayey TOPSOIL.
Medium strength orange sandy CLAY.
(NORTHAMPTON SAND FORMATION)
TRIAL PIT TERMINATED AT 1.06m DEPTH
Notes:
1. Trial pit side remained upright and stable
0.0
0.3
1.06
DESCRIPTION LEGEND DEPTH
(m)
0
10
33
52
70
103
123
149
Appendix 4
Overland Flow Calculations
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Appendix 5
Preliminary Attenuation Calculations
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