Report Type: - Phase 2: Ground Investigation Report Page 1 of 20 Project Name: - 20-467 Newsome Road, Newsome, Huddersfield HD4 6LS Prepared For: - Urban Group (York) Limited Prepared By: Rebecca Jordan Date: 26 th August 2020 Approved By: John Ditchburn Date: 26 th August 2020 The information and/or advice contained in this Phase 2: Ground Investigation Report is based solely on, and is limited to, the boundaries of the site, the immediate area around the site, and the historical use(s) unless otherwise stated. This ‘Report’ has been prepared to collate information relating to the physical, environmental and industrial setting of the site, and to highlight, where possible, the likely problems that might be encountered when considering the future development of this site for the proposed end use. All comments, opinions, diagrams, cross sections and/or sketches contained within the report, and/or any configuration of the findings is conjectural and given for guidance only and confirmation of the anticipated ground conditions should be considered before development proceeds. Agreement for the use or copying of this report by any Third Party must be obtained in writing from Arc Environmental Limited (ARC). If a change in the proposed land use is envisaged, then a reassessment of the site should be carried out. Solum House Unit 1 Elliott Court St Johns Road Meadowfield Durham DH7 8PN Tel: 0191 378 6380 e-mail: [email protected]www.arc-environmental.com Project No: 20-467 PHASE 2: GROUND INVESTIGATION REPORT URBAN GROUP (YORK) LIMITED PROPOSED RESIDENTIAL DWELLINGS NEWSOME ROAD NEWSOME HUDDERSFIELD HD4 6LS
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
The information and/or advice contained in this Phase 2: Ground Investigation Report is based solely on, and is limited to, the boundaries of the site, the immediate area around the site, and the historical use(s) unless otherwise stated. This ‘Report’ has been prepared to collate information relating to the physical, environmental and industrial setting of the site, and to highlight, where possible, the likely problems that might be encountered when considering the future development of this site for the proposed end use. All comments, opinions, diagrams, cross sections and/or sketches contained within the report, and/or any configuration of the findings is conjectural and given for guidance only and confirmation of the anticipated ground conditions should be considered before development proceeds. Agreement for the use or copying of this report by any Third Party must be obtained in writing from Arc Environmental Limited (ARC). If a change in the proposed land use is envisaged, then a reassessment of the site should be carried out.
Solum House Unit 1 Elliott Court St Johns Road Meadowfield Durham DH7 8PN Tel: 0191 378 6380 e-mail: [email protected] www.arc-environmental.com
Appendix I Appendix II Appendix III Appendix IV Appendix V
Location Plan, Aerial Photograph, Existing Site Layout Plan, Proposed Development Layout Plan Borehole and Trial Pit Location Plan & Borehole, Trial Pit Record Sheets, Mill Ponds Foundation Detail Sheet and Trial Pit Photographic Record Laboratory Testing Results (Geotechnical & Ground Contamination) Gas Monitoring Certificate Foundation Zoning Plan
As requested by Urban Group (York) Limited, following the result of a Geoenvironmental Appraisal undertaken by Sirius in 2017 (Ref. C1247), Phase 2: ground investigation works have been carried out over an area of land located off Newsome Road, Huddersfield. The site is currently occupied by two rectangular mill ponds with an area of rough grassland / vegetation in the southeast.
The intrusive investigation works comprised 7 no. windowless sampling boreholes (WS01 to WS07), 2 no. rotary boreholes (RBH01 and RBH02) and 2 no. mechanically excavated trial pits (TP01 and TP02). The locations can be seen on the Borehole and Trial Pit Location Plan, a copy of which can be seen in Appendix II. It should be noted that this plan is for orientating purposes only, as the positions shown are approximate and the plan is not to a standard scale.
The proposed development will involve draining and infilling the mill ponds prior to the erection of 26 no. residential dwellings with gardens and 41 no. car parking spaces. An area of public open space is also proposed.
2.0 Site Details Table 2.1
Site Name & Address: Land off Hart Street and Newsome Road, Newsome, Huddersfield HD4 6LS OS Grid Reference: 414448, 414795 (representative for the centre of the site).
Description of Location: The site is located approximately 2km to the south of Huddersfield town centre. Site Description: The north-western ‘two thirds’ of the site are occupied by two rectangular mill ponds. These
are separated by a thin strip of land covered in rough vegetation. The south-eastern third of the site is level rough grassland. Numerous mature trees lie along the southwestern boundary
of the site, with occasional trees along the remaining site boundaries. Site Boundaries: Northeast – Hart Street beyond which lies housing, Southeast – Newsome Road beyond
which lies housing, Southwest – Naomi Road beyond which lies housing and Northwest – Housing.
3.0 Scope of Works
Table 3.1 Client: Urban Group (York) Limited.
Project type: Proposed Residential Dwellings.
Site Location plan: See Appendix I.
Layout plans (existing): See Appendix I. Layout plan (proposed): See Appendix I.
Intrusive Investigation Works: 7 no. windowless sampling boreholes (WS01 to WS07) 2 no. rotary boreholes (RBH01 and RBH02)
CLEA Classification: Residential with home grown produce. Reporting: Factual & Interpretative including Level 1 Risk Assessment. Comments: Works were carried out in accordance with BS5930:2015 + A1:2020 and subsequent
laboratory testing in accordance with BS1377-1:2016 and BS EN ISO 14688/2:2018.
The information contained in this report is limited to the area of the site, as indicated on the Existing & Proposed Site Layout Plans shown in Appendix I, and to those areas accessible during the ground investigation. The depths of strata on the borehole record sheets are recorded from current ground levels. No topographical survey was requested or undertaken. Therefore, when considering the full scope of the development any features and / or issues not specifically mentioned in this report cannot be assumed to have been covered.
This ground investigation has been designed to provide information on the general ground and groundwater conditions where access would allow, within the boundaries of the site. The rationale behind the location of each exploratory hole is summarised in Table 4.1 on the following page.
Table 4.1 Potential issue Exploratory hole
Geotechnical considerations around area of the proposed development. WS01 to WS07
Site wide contamination assessment WS01 to WS07
Mill pond wall investigation TP01 and TP02
Coal mining investigation RBH01 and RBH02
4.1 Contamination Related Sampling & Site Protocols: -
All works associated with this ground contamination assessment and investigations have generally been completed in accordance with BS10175:2011 + A2:2017: Investigation of potentially contaminated sites – Code of practice & CLR11, with the following precautions specific to this project.
4.1.1 Ground Contamination Sampling: -
Samples were recovered by a representative of ARC Environmental Ltd. during the intrusive investigation works. All samples were stored at approximately c.2oC to c.8oC using cool boxes and ice packs prior to delivery to a UKAS/MCERTS accredited laboratory. Sampling was carried out in accordance with 'Technical Policy Statement 63: UKAS Policy on Deviating Samples'.
4.1.2 Avoiding Cross-Contamination between Sample Locations: -
To avoid possible cross-contamination of materials between soil horizons, drill casing was used to seal off the made ground. In addition, disposable plastic liners were used to collect samples from the windowless sampling boreholes carried out. The trial pits were backfilled in reverse order.
5.0 Ground Conditions
For an accurate description of the ground conditions encountered at each investigation position, reference should be made to the Borehole and Trial Pit Record Sheets in Appendix II. A summary of the soil profile for this site can be found in Table 5.1 below.
5.1 Soil Profile: -
Table 5.1 Type of Strata Depths Recorded
(BGL) Description & General Comments
DISTURBED TOPSOIL:
From 0.00m up to c.0.30m and
c.0.90m
Vegetation overlying clayey gravelly sand.
RESIDUAL SOIL: From c.0.30m up to c.1.80m and
2.30m
Initially soft (low strength) becoming firm and stiff (medium and high strength) CLAY with occasional cobbles.
SOLID GEOLOGY: (STANNINGLEY ROCK – UPPER
COAL MEASURES)
From c.1.80m up to c.2.00m and
c.20.00m
Medium dense to moderately weak weathered SANDSTONE.
bcgl = Below current ground levels
There was no visual or olfactory evidence of significant or ‘gross’ contamination (fuel, oils or asbestos) noted on or below the site areas during the ground investigation works.
Two no. trial pits were undertaken between the two mill ponds on the north of the site. TP01 identified the eastern pond wall comprises a concrete wall c.0.15m thick and at least 2.20m deep. TP02 identified the western pond wall comprises sandstone blocks which rely on the cohesive strata behind the wall to retain water in the pond. Excavation of TP02 on the eastern edge of the western pond resulted in some leakage of the pond water into the trial pit. This suggests the western pond wall comprising sandstone blocks, recorded as c.0.40m wide and at least 1.00m deep, is not watertight.
5.3 Groundwater: -
WS03 and WS04 encountered water ingress at depths of 2.10m and 2.40m bcgl, with standing water at c.1.92m in WS03 following completion of the exploratory period. All other exploratory holes, including WS04, were dry on completion. TP02 was recorded to have water ingress form the mill pond at c.0.35m bcgl, identifying the mill pond walls (sandstone blocks) are not watertight.
As a result, shallow water ingress may occur during future construction related excavations and it would be prudent to allow for introduction of groundwater control measures in order to take care of any localised ingresses of groundwater which may occur during the construction period, especially during the wetter periods of the year.
5.4 Coal Mining Risk Assessment: -
Geologically the site is recorded in an area free from drift although some clays associated with weathering are anticipated. An adjacent BGS borehole records siltstone and sandstone rock at a depth <3m. This was confirmed by the Sirius investigation with rock at c.2.00m to c.2.80m.
The solid geology is the Stanningley Rock (Upper Coal Measures) and we had initial confirmation from the Coal Authority in 2017 that the south east margin of the site lies in a Development High Risk Area associated with the 36 Yards Band Seam (recorded as less than 1m thick) recorded to be cutting across the southeast of the site, dipping away from the site to the southeast. However, discrepancies regarding the recorded position of the 36 Yards Band coal seam were later informed by the Coal Authority, locating the seam offsite. Recommendation within the Geoenvironmental Appraisal by Sirius were to drill to 20m in order to dismiss / confirm the presence of the Hard Bed coal seam below the site.
During the ground investigation 2 no. rotary holes were undertaken to 20m bgl to both confirm the 36 Yard Band coal seam and the Hard Bead coal seam are not present on or within influencing depth respectively. Neither of the rotary holes encountered any coal seams within 20m of the surface, hence the coal mining risk / risk of ground instability for the site is considered to be negligible.
6.0 Insitu Testing
6.1 Insitu Hand Shear Vane Tests: -
Insitu hand vane tests were carried out using portable hand vane tester on natural clay residual soil recorded within the boreholes. The in-situ hand vane tester takes direct readings of shear strength, three vane sizes allow for the direct determination of undrained shear strength of extremely low to high strength clays.
The peak vane value is determined by a calibrated scale ring built into the head assembly. The cross handle is used both to push the vane to the desired test depth and apply the shearing torque.
The results are summarised in Table 6.1 below and can also be found adjacent to the appropriate sample level, on the graphic borehole record sheets.
6.1 Insitu Hand Shear Vane Tests (Cont’d): - Table 6.1
Type of Strata Range of Sheer Strength Values Result Details
NATURAL CLAY (RESIDUAL SOIL)
14kN/m2 to >120kN/m2 Indicative of very low, low, medium and high strength clays.
6.2 Insitu Standard Penetration Tests (SPT’s): -
Insitu standard penetration tests (SPT’s) were carried out utilising a standard split spoon sampler (S) on the natural sand deposits noted within the boreholes, to determine the relative density of the materials tested. The results are shown as ‘N’ values on the graphic borehole record sheets, adjacent to the appropriate sample level. A summary of the test results can be seen in Table 6.2 below. Table 6.2
Type of Strata Range of SPT ‘N’ Values Result Details
NATURAL CLAY (RESIDUAL SOIL)
4 to 33
Indicative of soft, firm, stiff and very stiff residual soils.
WEATHERED SANDSTONE
(STANNINGLEY ROCK - UPPER COA MEASURES)
16 and blows of 59, 61 and 75 for limited penetration
Indicative of medium dense, very weak, weak and moderately weak deposits.
6.3 Insitu Ground Gas & Groundwater Monitoring: -
6.3.1 Hazardous Ground Gas Risk Assessment: -
Soil gas / vapour & water monitoring standpipes were installed within WS01, WS03 & WS05, primarily to check for the possible presence of hazardous ground gases. These monitoring wells were also utilised to monitor insitu shallow groundwater levels. A standard 50mm diameter HDPE standpipe, with gravel and/or geo-wrap surround, bentonite seal, gas valve cap and security cover, was installed at WS01, WS03 & WS05 to depths of between c.2.00m and c.3.00m bcgl. The soil gas and water levels were allowed to reach equilibrium, prior to the first monitoring visit and monitoring to date has been undertaken using a GFM 430 series soil gas analyser, with integral flow meter, and a Geotechnical Instruments electronic dip-meter.
In accordance with CIRIA Report C665, November 2007, and BS8485:2015 – Code of practice for the design of protective measures for methane and carbon dioxide ground gases for new buildings, as well as the results of the Phase 1: Desk Top Study Report carried out and these intrusive investigation works, it is felt that an adequate risk assessment can be undertaken based on the following limiting factors:
• The development has been considered as high sensitivity (Tables 5.5a & 5.5b – Typical/Idealised frequency and period of monitoring, after Wilson et al, 2005).
• The risk associated with the generation potential of a source is considered as very low, (assessment based on the environmental setting and results of the site investigations, etc.).
• Monitoring over a minimum of three months with a minimum six recorded readings (Table 5.5 – Typical /idealised frequency and period of monitoring after Wilson et al, 2005).
• Negligible flow rates have been recorded (Table 8.5 – Modified Wilson & Card classification).
• A targeted and phased programme of gas monitoring to be completed, which will try to obtain gas monitoring readings during varying atmospheric conditions, which covers the ‘worst case’ scenario for ground gas emissions to occur, particularly during rapid falls in atmospheric pressure (i.e. from c.1020mb and c.1010mb), and ideally during low atmospheric pressure (i.e. c.1000mb and below).
5.3 Insitu Ground Gas & Groundwater Monitoring (Cont’d): -
5.3.1 Hazardous Ground Gas Risk Assessment (Cont’d): -
A summary of the results for the visit undertaken to date, compared with the ‘inert’ background gas levels are presented in Table 5.2 below with a copy of the monitoring certificate attached in Appendix IV. A further five monitoring visits are scheduled and the results along with the final recommendations will be issued as an addendum letter to this report.
Table 5.2 Elevated levels shown Bold.
Position Date Atmospheric Pressure (mbar)
Water (m bgl)
CH4
(%v/v) LEL
(%v/v) CO2
(%v/v) O2
(%v/v) Flow Rate
(l/hr)
Background ~ ~ 0 0 0 21.0 <0.1
WS01 1001
(Steady*)
2.27 0.0 0.0 2.0 19.5 <0.1
WS03 07/08/20 1.59 0.0 0.0 1.5 20.4 <0.1
WS05 1.62 0.0 0.0 2.2 19.4 <0.1
5 visits remaining *Atmospheric trend taken from https://www.wunderground.com/ for Huddersfield
From the results undertaken to date, no levels of Methane (CH4) have been recorded, with detectible concentrations of Carbon Dioxide (CO2), up to a maximum level of 2.2% v/v, with associated reductions in oxygen (O2) concentrations (minimum 19.4% v/v). Negligible flow rates of <0.1l/hr have also been recorded.
Based on the results undertaken to date, in accordance with CIRIA Report C665, a preliminary risk assessment has been completed for this site, by converting the results in Table 5.2 to a gas screening value (GSV), calculated by multiplying the typical maximum gas concentrations with the recorded maximum positive flow rates (after Wilson & Card). Using the maximum values recorded, as no increased levels of Methane have been recorded to date, the gas screening value (GSV) for Carbon Dioxide only has been calculated, the results of which are shown below:
From the above assessment, in accordance with CIRIA C665, and considering the NHBC Traffic light system (low rise housing with ventilated underfloor void), the GSV values for both CH4 & CO2 are below the assessment GSV of 0.78 l/hr (Green classification), resulting in no gas protection measures being required. Alternatively, if the proposed development were to comprise ground bearing floor slabs within the structures, in accordance with CIRIA C665, the GSV for both CH4 & CO2 would also fall below the lower target concentration of 0.07l/hr and would also equate to a Characteristic Situation 1 site classification, resulting in no gas protective measures being required for the proposed development.
A further five mandatory visits have been scheduled for this site and the final results along with the final recommendations will be issued as an addendum to this report.
5.3.2 Groundwater: -
When considering the results of the groundwater monitoring completed to date, water levels have been recorded within the monitoring installations between a depth of c.1.59m and c.2.27m.
It would therefore be considered prudent to allow for the introduction of appropriate temporary groundwater control techniques, if excavations are required to extend to and / or below the depths at which groundwater has been recorded below this site. These techniques should also be designed to take care of any localised ingresses of surface water which may occur, during the construction period, especially if these works take place during the wetter periods of the year.
All laboratory geotechnical testing was carried out in accordance with BS1377-1:2016 by Professional Soils Laboratory (PSL) of Doncaster, South Yorkshire and Chemtech Environmental Limited, of Stanley, County Durham (UKAS accredited) unless otherwise stated.
7.1 Determination of pH & SO4: -
Representative samples of the topsoil and natural deposits recovered during the investigation works, were tested to determine their acidic (pH) and soluble sulphate (SO4) levels. The results are shown in Table 7.1 below and are also contained within the Chemtech Environmental Limited Analytical Report (Ref. 87893), a copy of which can be seen in Appendix III.
Table 7.1
Position Strata Depth (m) pH SO4(mg/l) Design SO4 Class ACEC Class
WS01 Disturbed Topsoil 0.50 8.3 67 DS-1 AC-1
WS01 Residual Soil 2.00 5.9 78 DS-1 AC-1
WS02 Disturbed Topsoil 0.30 7.1 17 DS-1 AC-1
WS03 Disturbed Topsoil 0.30 7.3 <10 DS-1 AC-1
WS04 Residual Soil 1.20 6.6 36 DS-1 AC-1
WS05 Disturbed Topsoil 0.50 7.4 10 DS-1 AC-1
WS06 Disturbed Topsoil 0.30 7.2 20 DS-1 AC-1
WS07 Disturbed Topsoil 0.20 7.2 24 DS-1 AC-1
ACEC = Aggressive Chemical Environment for Concrete site classification
From these results the pH values range from 5.9 up to 8.3, whilst the amount of soluble sulphate present falls within the negligible range (<500mg/l). Therefore, in accordance with BRE Special Digest 1: 2005, the site can be given a classification of Class DS-1. In addition, when assuming mobile groundwater, the assessment of the Aggressive Chemical Environment for Concrete (ACEC), is AC-1.
7.2 Determination of Liquid & Plastic Limits: -
Representative samples (5 no.) of the natural clays recovered from across the proposed development area were tested to determine their liquid and plastic limits, so that these materials could be classified. The results are summarised in Table 7.2 below and are also contained in the PSL Analytical Report (Ref. PSL20/3839), a copy of which is contained in Appendix III.
Table 7.2
Position Depth (m) M/C (%) LL PL PI Class % Passing 425m Sieve
WS01 1.10 34 67 32 35 CH 100
WS02 2.00 21 46 24 22 CI 100
WS03 2.80 15 37 20 17 CL 47
WS04 1.80 16 38 22 16 CI 100
WS06 1.70 25 51 25 26 CI 100 M/C = Moisture Content, LL = Liquid Limit, PL = Plastic Limit, PI = Plasticity Index, CL = Clay Low, CI = Clay Intermediate, CH = Clay High
From these results the samples tested, when plotted on the plasticity chart, fall within the low, intermediate and high plasticity ranges, and from the resulting plasticity indices, have a low and moderate volume change
(shrinkage or swelling) potential, when taking into account the amount passing the 425m sieve.
Therefore, some of the natural clays tested may undergo significant changes in volume, if large changes in their natural moisture content were to occur due to seasonal variations or the like and if new foundations were to be based within these materials, they would need to be taken down to a minimum depth of 0.90m below finished ground levels.
7.2 Determination of Liquid & Plastic Limits (Cont’d): -
However, an increase in founding depth may be required to reach competent strata and also if the proposed development is within close proximity to existing or envisaged vegetation. An increase in the minimum foundation depth may also be required, even if trees are to be removed, to avoid the effects of volume change. Reference should be made to BS5837: 2012, Trees in Relation to Design, Demolition and Construction’, along with the NHBC Standards, ‘Building near trees’.
Representative samples of disturbed topsoil recovered from across the site were dispatched to Chemtech Environmental Limited of Stanley, Co. Durham so that soil contamination screening could be carried out. In total 6 no. representative samples were screened using a standard generic contamination suite (based on the current CLEA SGV listed analytes with historical additions), which is used to assess the disturbed topsoil encountered on the site.
No significant evidence of any fuel /oil type or ash contamination was noted within the exploratory positions carried out were noted within the topsoil. However, for completeness, the samples were tested for metals, Speciated PAH (Polycyclic Aromatic Hydrocarbons), Speciated TPH (Total Petroleum Hydrocarbons) and asbestos.
The catalogue of testing results can be found in the Chemtech Analytical Report (Ref. 87893), attached in Appendix III, and the total analysis carried out is summarised below.
• 6 no. soil sample screened for a generic (metals and non-organics) soil suite which includes the following determinands; Arsenic, Cadmium, Chromium (III & VI), Copper, Lead, Mercury, Nickel, Selenium, Zinc, Cyanide and Total Organic Carbon (TOC).
• 6 no. soil sample screened for Speciated Polycyclic Aromatic Hydrocarbons (PAH’s) – based on the current USEPA 16 PAH’s + Benzo(j)fluoranthene.
• 6 no. soil sample screened for Speciated Total Petroleum Hydrocarbons (Aliphatic / Aromatic + BTEX)).
• 6 no. samples screened for the presence of asbestos.
These results have been used to carry out a Level 1: Quantitative Human Health Risk Assessment for the ground contamination present and are discussed in further detail in Section 8.0 below and on the following pages.
8.0 Ground Contamination Risk Assessment
8.1 Methodology: -
Following completion of the contamination screening undertaken on various samples from across the site, a Level 1 quantitative ground contamination risk assessment has been undertaken, generally in accordance with CLR11: Model Procedures for the Management of Land Contamination. This quantitative ground contamination risk assessment uses the current UK practice for assessing the risks from land contamination, which is based on the established source-pathway-receptor pollutant linkage methodology and ‘suitable for use’ approach (Part IIA, EPA 1990 - inserted through Section 57 EA 1995).
Based on the Conceptual Site Model (CSM) for this site (described further in the following Section 8.2), a site specific screening strategy for the site has been developed (see Section 7.3) and the risks from potential contaminants have been assessed for Human Health. The results of the risk assessment can be found in Section 8.3.
From the findings of the intrusive investigation works, a Conceptual Site Model (CSM) has been developed for this site, with Table 8.1 on the following page summarising the various contamination sources, plausible migration pathways and potentially sensitive receptors identified for this site, assuming no remediation, additional protection measures and/or removal of the sources of contamination takes place.
Table 8.1
Sources (S) Pathways (P) Receptors (R) S1 Made ground (probably
disturbed topsoil) present across proposed area.
Elevated contaminants have been identified locally within
the topsoil.
P1 Ingestion & Dermal Contact.
R1 Human health – Future end users (Residents).
P2 Air – Inhalation of vapours (indoor & outdoors) and
contact with dust.
R2 Groundwater within the Secondary A Aquifer within the
Bedrock Strata.
P3 Plant uptake. S2 Potential for hazardous ground
gas. P4 Migration through existing
services. R3 Building materials & protection
of water pipes.
P5 Direct contact with building materials.
R4 Adjacent sites*.
P6 Surface run off & Infiltration.
R5 Flora and fauna*.
* = Not included in the Human Health & Controlled Waters Risk Assessment
8.2.1 Sources: -
The site is covered by a layer of probably disturbed or imported topsoil (up to c.0.90m in thickness). The topsoil does not contain any anthropogenic debris and is comprised of natural strata.
There was no significant visual, olfactory or analytical evidence of significant heavy or gross contamination, such as waste oils, fuels, ash, etc. However, for completeness the potential for hydrocarbon-based contamination (PAH’s & TPH’s) for this site have been assessed. In addition, although no visual evidence of Asbestos (fibres or fragments) were noted, the potential for Asbestos has also been assessed.
8.2.2 Pathways: -
When considering the proposed end use, and without considering treatment, removal or protection measures, there are some potential plausible pathways available for direct contact, dermal contact, ingestion, inhalation, wind (dust / particulate), volatilization, and vertical and lateral transportation below the site.
Within the CLEA Risk Assessment Model for Human Health, there are 3 exposure mediums considered for on site receptors, comprising ingestion of soil containing contaminants, inhalation of contaminated dust/vapours and dermal contact, with up to 10 no. exposure pathways considered, as shown on the following page.
1. Ingestion of soil and indoor dust 2. Consumption of homegrown produce and attached soil 3. Dermal contact (indoor) 4. Dermal contact (outdoor) 5. Inhalation of dust (indoor) 6. Inhalation of dust (outdoor) 7. Inhalation of vapour (indoor) 8. Inhalation of vapour (outdoor) 9. Oral background intake 10. Inhalation background intake.
Where the future site has hard cover and below new structures, the majority of these pathways will not be available.
When considering the potential pathways for leachate migration, where either hard cover and / or future surface water drainage systems are present, the potential effects of surface infiltration or contaminated surface water runoff will be greatly reduced. Similarly, when considering the construction work force, exposure pathways through direct contact, ingestion and dust inhalation will be available during part of the construction process, and therefore adequate PPE should be provided to protect the work force during this period.
Within the CLEA Risk Assessment Model for Human Health, the potential receptors are assessed initially on site end use, followed by a delineation of age category (i.e. child or adult), with default settings for Residential, Allotment and Public Open Space (Park) end uses based on a child aged 0 to 6 years, Public Open Space (Residential) based on a child aged 3 to 9 and Commercial end uses based upon a working exposure period of up to 49 years (i.e. 16 to 65).
Key generic assumptions for Residential and Public Open Space (Residential) are based upon a typical residential property, consisting of a two-storey small terraced house, with private garden, and a Commercial end use based upon a typical commercial or light industrial property, consisting of a three-storey office building (pre-1970). No buildings are anticipated for Allotment or Public Open Space (Park) end uses.
Within the CLEA Risk Assessment Model for Human Health there are 6 no. generic end use categories presently in use, as follows.
1) Residential - with home grown produce, 2) Residential - without home grown produce, 3) Allotments, 4) Commercial 5) Public Open Space – Residential, 6) Public Open Space - Park
For this Level 1 Risk Assessment, the end use category for this site has been identified as:
1) Residential - with home grown produce
When considering the environmental setting, no testing has been carried out with regards to controlled waters risk assessment.
8.3 Level 1 Risk Assessment (Human Health): -
8.3.1 Metals, PAHs and TPHs: -
The soil screening results have been risk assessed by comparing the maximum values (CM) recorded for each analyte to the critical concentration values (CC) chosen for this site. The results of the analysis and risk assessment have been summarised in Table 8.2 on the following page and have identified the following;
• The maximum concentration (CM) values for arsenic and lead exceeds the chosen critical concentration values (CC) value for this site.
• The maximum concentration (CM) values for several PAHs (Benzo(a)anthracene, Benzo(a)pyrene, Benzo(b)fluoranthene and Dibenz(ah)anthracene) exceed the CC values for this site.
• None of the CM values for any of the remaining analytes screened for exceed the CC values for this site.
• When considering these results, the probably disturbed / imported topsoil in the south of the site represents a potential risk to the end users, and therefore treatment, removal, protection measures and / or further detailed quantitative risk assessment will be required.
Benzo(a)pyrene 3.0(1) 6 17.12 Yes 3 (WS01, WS02 and WS03)
Benzo(b)fluoranthene 3.7(1) 6 17.47 Yes 3 (WS01, WS02 and WS03)
Benzo(ghi)perylene 350(1) 6 10.84 No 0
Benzo(k)fluoranthene 100(1) 6 7.16 No 0
Chrysene 27(1) 6 14.82 No 0
Dibenz(ah)anthracene 0.3(1) 6 2.64 Yes 3 (WS01, WS02 and WS03)
Fluoranthene 890(1) 6 35.12 No 0
Fluorene 860(1) 6 1.89 No 0
Indeno(123cd)pyrene 41(1) 6 12.16 No 0
Naphthalene 13(1) 6 0.55 No 0
Phenanthrene 440(1) 6 22.04 No 0
Pyrene 2000(1) 6 29.75 No 0 VPH Aliphatic (>C5-C6) 160(1) 6 <0.1* No 0
VPH Aliphatic (>C6-C8) 530(1) 6 <0.1* No 0
VPH Aliphatic (>C8-C10) 150(1) 6 <0.1* No 0
EPH Aliphatic (>C10-C12) 760(1) 6 <4* No 0
EPH Aliphatic (>C12-C16) 4300(1) 6 37 No 0
EPH Aliphatic (>C16-C35) 110000(1) 6 1045 No 0
EPH Aliphatic (>C35-C44) 110000(1) 6 831 No 0
VPH Aromatic (>EC5-EC7) 300(1) 6 <0.01* No 0
VPH Aromatic (>EC7-EC8) 660(1) 6 <0.01* No 0
VPH Aromatic (>EC8-EC10) 190(1) 6 <0.01* No 0
EPH Aromatic (>EC10-EC12) 380(1) 6 <1* No 0
EPH Aromatic (>EC12-EC16) 660(1) 6 3 No 0
EPH Aromatic (>EC16-EC21) 930(1) 6 96 No 0
EPH Aromatic (>EC21-EC35) 1700(1) 6 88 No 0
EPH Aromatic (>EC35-EC44) 1700(1) 6 13 No 0
Benzene 0.37(1) 6 <0.01* No 0
Toluene 660(1) 6 <0.01* No 0
Ethylbenzene 260(1) 6 <0.01* No 0
m & p-Xylene 310(1) 6 <0.02* No 0
o-Xylene 330(1) 6 <0.01* No 0 (1) = LQM CIEH Suitable 4 Use Levels (S4UL Nov 2014 (Revised August 2015)) – Residential with home grown produce (6% SOM)). (2) = CL:AIRE C4SLs – Residential with home grown produce, (3) = Atkins ATRISK SSV Residential with the consumption of home-grown produce (Mar 2011). * = Site Value (CM) less than analytical detection limit. Note = All units are mg/kg.
Representative samples of the topsoil recovered from below the proposed development area have been screened for Asbestos, to determine whether any unidentified asbestos was present within these materials. The results are summarised in Table 8.3 below and have identified the following:
Table 8.3 NAD = No Asbestos Detected.
Position Depth (m)
Chrysotile (white)
Amosite (brown)
Crocidolite (blue)
Anthophyllite Actinolite Tremolite
WS01 0.50 NAD NAD NAD NAD NAD NAD
WS02 0.30 NAD NAD NAD NAD NAD NAD
WS03 0.30 NAD NAD NAD NAD NAD NAD
WS05 0.50 NAD NAD NAD NAD NAD NAD
WS06 0.30 NAD NAD NAD NAD NAD NAD
WS07 0.20 NAD NAD NAD NAD NAD NAD
From these results, it can be seen no asbestos fibres have been detected and therefore the topsoil below the proposed development area is not felt to represent a risk with regards to asbestos.
9.0 Conclusions & Recommendations
9.1 Ground Conditions: -
From the information gained during these intrusive ground investigation works, topsoil was generally recorded to depths of between c.0.60m to c.0.90m below current ground level (bcgl), generally comprising clayey gravelly sand.
The underlying residual soils comprised initially soft (low strength) becoming firm and stiff (medium and high strength) clay with occasional cobbles to a maximum depth of 2.80m bcgl. Sandstone overlying mudstone solid deposits were encountered from c.2.00m to a maximum proven depth of 20.00m bcgl and no coal seams were encountered.
9.2 Mill Pond Wall Construction: -
Investigations undertaken between the two mill ponds identified the eastern pond wall comprises a concrete wall c.0.15m thick and at least 2.20m deep. The western pond wall comprises sandstone blocks which rely on the cohesive strata behind the wall to retain water in the pond, excavating in this area resulted in some leakage of the pond into the trial pit. The sandstone block wall is c.0.40m wide and at least 1.00m deep.
9.3 Groundwater: -
Following the draining of the mill ponds shallow water ingress is not anticipated to be problematic with regards to construction related excavations. Nonetheless, it would be prudent to allow for introduction of groundwater control measures in order to take care of any localised ingresses of groundwater which may occur during the construction period, especially during the wetter periods of the year.
9.4 Coal Mining Risk Assessment: -
The solid geology for the site is recorded as the Stanningley Rock, Upper Coal Measures. Rotary coring undertaken as part of the intrusive investigation confirmed the 36 Yard Band coal seam was not present on the site and the Hard Bead coal seam is not within influencing depth, hence the coal mining risk / risk of ground instability for the site is considered to be negligible.
When considering the proposed development, including draining and infilling the former ponds and ground conditions identified, the site has been separated into two areas for the purpose of foundation solutions, see Appendix V for the Foundation Zoning Plan.
Former Mill Pond Area: Option 1: Mass trench fill taken down to the sandstone anticipated to be c.2.00m to c.3.50m bcgl, with an
available bearing capacity of 200kN/m2. Option 2: Raft foundations on engineered fill. The fill will require strict verification and confirmatory
testing to create a building platform and satisfy regulators.
South of the site (out with the Mill Ponds): For plots located outside the area of the former mill ponds foundations can be based at c.1.00m to c.1.20m bcgl within the firm clay where an allowable bearing capacity of 80kN/m2 is available.
When considering the risk to building materials, it is recommended that a concrete design class of DS-1 and ACEC class of AC-1 is used for all foundations and buried concrete within the natural deposits the made ground materials. Recourse to the relevant utility suppliers should be made for their advice/comments regarding any service material precautions necessary.
9.6 Ground Contamination: -
From the results of the contamination screening carried out on this site and the Level 1 Risk Assessment (Section 8.0), it can be seen that the disturbed topsoil below the site has been locally impacted by Arsenic, Lead and PAH’s which exceed the critical concentrations chosen for this site and therefore, remedial measures will be necessary to protect the end users.
9.7 Preliminary Remediation Strategy: -
From the results of the Level 1 Risk Assessment elevated levels of Arsenic, Lead and several PAH’s have been recorded that represent a potential risk to the proposed end users. Remediation technologies for metal and PAH contaminated soils include chemical oxidation, biological treatments, excavation and removal or capping.
In this instance, depending on finished ground levels, the simplest and most expedient remedial options would be to either install a clean cover capping system below all areas of soft landscaping or to fully remove the made ground from all areas of soft landscaping. Where buildings and areas of hardstanding are proposed then the source-pathway-receptor pollutant linkage will not exist and the made ground can remain insitu with no requirement to incorporate clean cover materials.
If a capping layer is the preferred remedial option, this should be a minimum of 600mm thick including a suitable topsoil growing medium and should be placed in all gardens and landscaped areas.
Where remedial works are completed across the site, confirmatory validation testing and photographic evidence of the chosen remediation strategy would be required by the Local Authority.
Following the gas reading undertaken to date gas protection measures are considered to not be required. However, this may change following the completion of the five remaining visits. If hazardous ground gas protection measures are required, a Remediation Strategy / Verification Plan will also be required. Appropriate gas protection measures should be selected based on the characteristic situation using the guidance contained in Section 7 of the BS8485:2015 + A1:2019 document.
Prior to any remedial works being undertaken, a remediation strategy may need to be prepared, this should be agreed with the LA, and once implemented, the remediation work should be validated by a suitably qualified Geo-environmental Engineer to ensure that all works are being completed in strict accordance with the agreed Remediation Strategy.
9.8 General Comments: -
If during future redevelopment works, any excavated materials are to be discarded and removed from this site as a waste to landfill, these materials can be classified using HazWasteOnlineTM software in accordance with the ‘Guidance on the Classification and Assessment of Waste (1st Edition 2015) – Technical Guidance WM3, Version 1.1 June 2018’.
Where excavated materials need discarding to accommodate new foundations additional analysis and screening may be required once each specific waste stream has been identified and the volume of material to be disposed of has been calculated, since the amount of screening required, including any pre-disposal WAC screening, will be dependent upon the final volume of material to be disposed of.
With regards to asbestos in soil, where we have sampled and tested for asbestos this is discussed in the report. Whilst we would target any asbestos sampling and testing in accordance with a Conceptual Site Model and site findings, there is always the possibility, along with other contamination, that undiscovered asbestos exists between sample locations and the possibility of unknown asbestos exists on all sites, particularly brownfield sites where previous buildings have been demolished, where there were previous features that were infilled (old hollows, pits etc) or where significant quantities of materials such as demolition and brick rubble exist.
For future site works, adequate lateral trench support will be required for excavations, in order to prevent trench wall collapse or over excavations, as well as to create a safe working environment, and any excavations on this site should remain open for as short a period as possible, since some of these materials may be susceptible to deterioration, if left open to the natural elements for any significant period of time.
It is also recommended for any new developments, adequate surface drainage should be designed and installed by a competent contractor, in order to prevent surface water ‘ponding’ or collection, during and post construction, particularly where the existing surface drainage system is disrupted or damaged.
In addition, for deeper excavations, drainage, service runs or the like that may pass close to or beneath any proposed new foundations, these should be undertaken with care and completed prior to the preparation of any new foundations, so as not to allow any loose or granular material to move or ‘flow’, thus causing settlement to occur to any new foundations based at a higher level.
An “observational technique” can be applied to the design and construction of this site, and where ground conditions seem to vary from that indicated from the conceptual ground model derived from works to date, then advice from a suitably qualified Engineer should be sought.
A copy of the Laboratory Schedule of accredited tests as issued by UKAS is attached to this report. This certificate is issued in accordance with the accreditation requirements of the United Kingdom Accreditation Service. The results
reported herein relate only to the material supplied to the laboratory. This certificate shall not be reproduced other than in full, without the prior written approval of the laboratory.
Checked and Approved Signatories: R Gunson A Watkins R Berriman (Director) (Director) (Quality Manager) L Knight S Eyre S Royle
(Senior Technician) (Senior Technician) (Laboratory Manager) Page 1 of
Solum House Unit 1 Elliott Court St Johns Road, Meadowfield Durham DH7 8PN
For the attention of: Rebecca Jordan Contract Title: Newsome Road, Huddersfield
Date Received: 30/7/2020 Date Commenced: 30/7/2020 Date Completed: 7/8/2020 Notes: Opinions and Interpretations are outside the UKAS Accreditation
* Denotes test not included in laboratory scope of accreditation $ Denotes test carried out by approved contractor
Hole Sample Sample Top Base
Number Number Type Depth Depth m m
WS01 B 1.10 Brown mottled grey slightly sandy very silty CLAY.WS04 B 1.80 Brown mottled grey sandy very silty CLAY.WS06 B 1.70 Brown mottled grey sandy very silty CLAY.WS02 B 2.00 Brown mottled grey sandy very silty CLAY.WS03 B 2.80 Brown mottled grey sandy very clayey very silty GRAVEL.
Contract No:PSL20/3839Client Ref:
4043 20-466
SUMMARY OF LABORATORY SOIL DESCRIPTIONS
Description of Sample
Newsome Road, Huddersfield
(BS1377 : PART 2 : 1990)
Moisture Linear Particle Liquid Plastic Plasticity PassingHole Sample Sample Top Base Content Shrinkage Density Limit Limit Index .425mm Remarks
Number Number Type Depth Depth % % Mg/m3 % % % %m m Clause 3.2 Clause 6.5 Clause 8.2 Clause 4.3/4 Clause 5.3 Clause 5.4
WS01 B 1.10 34 67 32 35 100WS04 B 1.80 16 38 22 16 100 Intermediate plasticity CI.WS06 B 1.70 25 51 25 26 100 Intermediate plasticity CI.WS02 B 2.00 21 46 24 22 100 Intermediate plasticity CI.WS03 B 2.80 15 37 20 17 47
SYMBOLS : NP : Non Plastic * : Liquid Limit and Plastic Limit Wet Sieved.
Monitoring order is from Left to Right across table
Monitoring should be for Not Less than 3 minutes However, if high concentrations of gasses initially recorded, monitoring should be for up to 10 minutes
N/A = Not applicable = Off the scale
Cf = PID compensation Factor (1-10) - Must be used to multiply the PID reading to give an accuate measure of the total hydrocarbons in the borehole when methane is present
Hex = Hexane (Valid and in range up to 2.000%) - Recorded when abnormally high methane is present.
PID = Photo Ionisation Detector (Calibrated to Isobutylene)