Mr Will Thomson Radmore Rocester Ltd Bloomfield Riggs Lane ...
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GRM Development Solutions Ltd Laurus House First Avenue Centrum 100 Burton upon Trent Staffordshire DE14 2WH Tel: 01283 551 249 Fax: 01283 211 968 Web: www.grm-uk.com Our Ref: P7660\GAL Date: 1 st February 2017 Mr Will Thomson Radmore Rocester Ltd Bloomfield Riggs Lane Ashbourne DE6 2FD4 Attention of Mr Will Thomson Dear Will, Re: Gas Addendum Letter for Eyes Farm, Rocester The gas monitoring programme at the above site is now complete. The assessment below supersedes any information regarding gas protection measures that has previously been given and should be submitted to the regulatory bodies for approval. The Phase I desk study identified the following potential sources of ground gas: Made Ground over most of the site and partially over the infilled pond area. Infilled Mill Pond (extent shown on the gas monitoring location plan. Due to the potential sources of ground gas, the desk study classified the risk to the end user from harmful ground gases as moderate (based on BS8576). The ground investigation identified the following potential sources of ground gas: Made Ground comprising CLAY with brick, quartzite and charcoal gravel was encountered to shallow depths of between 0.35m and 1.1m begl in WS01, WS04, WS05 and WS07. Infilled mill pond strata comprising very soft to soft dark grey mottled black silty sandy CLAY was encountered in WS02, WS04, WS05 and WS06 between depths of 0.3m and 3.5m begl. As the proposed end use has been classified as high sensitivity (residential with gardens), five gas/water monitoring standpipes have been installed across the site (WS01, WS02, WS05, WS06 and WS07) and targeted at both the natural and infilled mill pond strata in order to assess the natural gas regime and the potentially gassing infilled mill pond strata. On the basis of the confirmed sources of ground gas and proposed end use, gas monitoring has been carried out fortnightly over a three month period from 14 th November 2016 to 30 th January 2017, to assess the risk posed to the end user from potentially harmful ground gases.
Transcript of Mr Will Thomson Radmore Rocester Ltd Bloomfield Riggs Lane ...
GRM Development Solutions Ltd Laurus House First Avenue Centrum 100 Burton upon Trent Staffordshire DE14 2WH
Tel: 01283 551 249 Fax: 01283 211 968 Web: www.grm-uk.com
Our Ref: P7660\GAL Date: 1
st February 2017
Mr Will Thomson Radmore Rocester Ltd Bloomfield Riggs Lane Ashbourne DE6 2FD4
Attention of Mr Will Thomson Dear Will, Re: Gas Addendum Letter for Eyes Farm, Rocester The gas monitoring programme at the above site is now complete. The assessment below supersedes any information regarding gas protection measures that has previously been given and should be submitted to the regulatory bodies for approval. The Phase I desk study identified the following potential sources of ground gas:
Made Ground over most of the site and partially over the infilled pond area.
Infilled Mill Pond (extent shown on the gas monitoring location plan. Due to the potential sources of ground gas, the desk study classified the risk to the end user from harmful ground gases as moderate (based on BS8576). The ground investigation identified the following potential sources of ground gas:
Made Ground comprising CLAY with brick, quartzite and charcoal gravel was encountered to shallow depths of between 0.35m and 1.1m begl in WS01, WS04, WS05 and WS07.
Infilled mill pond strata comprising very soft to soft dark grey mottled black silty sandy CLAY was encountered in WS02, WS04, WS05 and WS06 between depths of 0.3m and 3.5m begl.
As the proposed end use has been classified as high sensitivity (residential with gardens), five gas/water monitoring standpipes have been installed across the site (WS01, WS02, WS05, WS06 and WS07) and targeted at both the natural and infilled mill pond strata in order to assess the natural gas regime and the potentially gassing infilled mill pond strata. On the basis of the confirmed sources of ground gas and proposed end use, gas monitoring has been carried out fortnightly over a three month period from 14th November 2016 to 30th January 2017, to assess the risk posed to the end user from potentially harmful ground gases.
carole.booth
Text Box
P_2016_01513 1 GAS ADDENDUM LETTER FINAL RECEIVED 03.02.17
The post fieldwork monitoring has been designed to identify and assess the groundwater and gas regimes below the site. The results are enclosed for reference and are summarised below:
Well ID (No. of
Readings)
Response Zone / Strata
Contamination Methane (%v/v)
Carbon Dioxide (%v/v)
Oxygen (%v/v)
Gas Flow Max (l/h)
WS01 (6) 1-5m / Nat None 0-0 0-3.9 16.2-21 0.0
WS02 (6) 0.7-1.7m / Infill Infilled ground 0-0 0-7.6 12.2-21 0.0
WS05 (6) 0.5-2m / Infill Infilled ground 0-0 0-6.1 10.5-21 0.0
WS06 (6) 1-3.5m / Infill Infilled ground 0-0 0-4.5 4.1-21 0.0
WS07 (6) 1.2-2.8m / Nat None 0-0 1-2.3 18.5-20.7 0.0
Notes: Atmospheric Pressure: 996mb-1023mb
Groundwater The monitoring program has confirmed the general presence of shallow groundwater beneath the site, in particular window sample boreholes WS01 and WS06. Groundwater was recorded between 3.52m begl and 3.95 begl. WS02, WS05 and WS07 did not record any groundwater during the monitoring period. Although the monitoring programme has identified the majority of window sample holes to not have groundwater, the standpipes were generally targeted at a shallower depth than the underlying river terrace deposits, which for the most part were encountered as wet during the ground investigation. Therefore, any deeper excavations, particularly for sewers, into granular material underlying the mill pond strata may require dewatering techniques. Ground Gas Risk Assessment The primary guidance document to determine if gas protection measures are required is BS8485:2015. This uses hazardous gas flow rates (Qhg), which are gas concentrations multiplied by borehole flow rates, to derive a Gas Screening Value (GSV) for the site. The gas regime is then determined based on the GSV and other limiting factors including gas concentrations and flow rates. Methane concentrations and flow rates above the monitor’s lower limits of detection were not detected during monitoring period. Therefore, in the following assessment a default methane concentration of 0.1% v/v and a default flow rate of 0.1l/hr has been used. Using the maximum default methane concentration of 0.1%v/v and the default flow rate of 0.1l/hr a Qhg of 0.0001l/hr has been calculated for methane. Using the maximum recorded steady state carbon dioxide concentration of 7.6%v/v and the default flow rate of 0.1l/hr a Qhg of 0.0076l/hr has been calculated for carbon dioxide. On this basis the GSV for the site is determined as 0.0076l/hr. Although the GSV is less than 0.07l/hr, concentrations of carbon dioxide have been recorded in excess of 5% and as such, further consideration has been given to the most appropriate Characteristic Situation. It is considered that as the results are typically above 5%, the site should be assessed as CS2; therefore, gas protection measures are necessary. Once this assessment has been agreed with the appropriate regulars, a Gas Protection Measures Design and Verification Plan will be required (in line with CIRIA C735); however, at this stage, allowance should be made for the use of a beam and block floor slab with minimal penetrations and a proprietary gas resistant membrane (which meets the requirements of BS8584:2015 such as Monarflex Reflex Super) installed to an appropriate standard by a qualified contractor with independent validation and integrity testing.
As gas protective measures are required, it is recommended that a Gas Protection Measures Design and Verification Plan is produced and agreed with the Local Authority. If you would like us to undertake this on your behalf, then please provide contact details and a Planning Reference. It may be possible to reduce this assessment if further gas monitoring is undertaken. Equally it could result in the same conclusion, therefore at this stage it is recommended that gas protection measures are utilised. An alternative to installing the gas protection measures would be to remove the mill pond material and backfill with a suitably clean material. If this option is taken, it is recommended that the backfill is engineered in such a way that the foundations of the proposed development may found directly onto the new material. Further gas monitoring will be required as the gas regime of the site will have changed. If the backfilled material is used for foundation purposes, geotechnical testing will be required to confirm it is fit for purpose. Depleted oxygen has been identified on one visit. No remedial measures are required. However the use of suitable PPE should be enforced during the ground works stage of construction and appropriate precautions should be taken when site workers are entering or working in confined spaces.
We trust this is suitable for you current requirements, should you require any further information or would like any clarification of the points raised please do not hesitate to contact us. Yours sincerely, for GRM Development Solutions Ltd
Russell Hurcombe MGeoSci (Hons) FGS Geologist
Clive Kirby FGS C.Geol Principal Geologist
Enc: P7660 Gas Monitoring Location Plan P7660 Gas Monitoring Results
GRM Development Solutions provides multi-disciplinary consultancy services, UK-wide: • Geotechnical and Geo-environmental Services
• Civil and Infrastructure Services
• Structural Engineering Services
• Construction Management
• Site Services
AP P E NDI X
A
Tel: 01283 551249 Fax: 01283 211968
[email protected] www.grm-uk.com
PROJECT No: DRAWING No:
DESIGN/DRAWN : DATE:
SCALE@SIZE : ISSUE:
TITLE:
PROJECT:
CLIENT:
DO NOT SCALE NOTES:
NTS FINAL
Exploratory Hole Location Plan
RDH
Figure 1
© GRM Development Solutions Ltd © Crown Copyright. AL 100014100
GRM Development Solutions Ltd Laurus House, First Ave, Centrum 100,
Burton-on-Trent, Staffordshire Tel: 01283 551 249 Fax: 01283 211 968
[email protected] www.grm-uk.com
November 2016
Eyes Farm, Rocester
Radmore Ltd.
P7660
WS01
Window Sample
Window Sample No.
Approximate Site Boundary
WS06
WS05
WS04
WS07
WS03
WS01
WS02
Approximate line of former mill pond TBC
GRM Development Solutions provides multi-disciplinary consultancy services, UK-wide: • Geotechnical and Geo-environmental Services
• Civil and Infrastructure Services
• Structural Engineering Services
• Construction Management
• Site Services
AP P E NDI X
B
Tel: 01283 551249 Fax: 01283 211968
[email protected] www.grm-uk.com
In-Situ Gas Monitoring Results
Project Name: Eyes Farm, RocesterProject Number:Client: Radmore Ltd.Date:Weather:Atmospheric Pressure (mb): 1013Pressure Trend:Equipment:Operator:
Well ID
Top Base Strata Peak Steady Peak Steady Low Steady Peak Steady Peak Steady
WS01 1.0 5.0 Nat 0.00 0.00 3.90 3.90 16.20 16.20 0.0 0.0 N/R N/R 3.95 4.68WS02 0.7 1.7 Infill 0.00 0.00 0.00 0.00 20.70 20.70 0.0 0.0 N/R N/R N/D 1.70WS05 0.5 2.0 Infill 0.00 0.00 2.50 2.50 18.10 18.10 0.0 0.0 N/R N/R N/D 2.82WS06 1.0 3.5 Infill 0.00 0.00 2.20 2.20 17.50 17.50 0.0 0.0 N/R N/R N/D 3.78WS07 1.2 2.8 Nat 0.00 0.00 1.50 1.50 19.30 19.30 0.0 0.0 N/R N/R N/D 2.85
Comments:
NotesL.E.L. Lower Explosive Limit (100% L.E.L.'= 5% Flammable Gas) Highlighted cell for following conditions:N.D. Not Detected a. Methane ≥1% v/vN.R. Not Recorded b. Carbon Dioxide ≥5% v/vPID Photo-Ionising Detector MG Made Ground% By volume NS Natural Strata
14 November 2016Rain
Falling
WS BAILED
Gas Data LMSXiLiam Press
P7660
Response Zone (mbegl) Total WellDepth (mbegl)
Ground Gases Groundwater
Methane (%v/v) Carbon Dioxide (%v/v) Oxygen (%v/v) Gas Flow (l/h) PID Reading (ppm) Depth toGroundwater
(mbegl)
In-Situ Gas Monitoring Results
Project Name:Project Number:Client:Date:Weather:Atmospheric Pressure (mb): 1018Pressure Trend:Equipment:Operator:
Well ID
Top Base Strata Peak Steady Peak Steady Low Steady Peak Steady Peak Steady
WS01 1.0 5.0 Nat 0.00 0.00 0.60 0.60 20.00 20.00 0.0 0.0 N/R N/R 3.75 4.66WS02 0.7 1.7 Infill 0.00 0.00 0.00 0.00 20.00 20.00 0.0 0.0 N/R N/R N/D 1.71WS05 0.5 2.0 Infill 0.00 0.00 0.00 0.00 21.00 21.00 0.0 0.0 N/R N/R N/D 2.47WS06 1.0 3.5 Infill 0.00 0.00 0.00 0.00 21.00 21.00 0.0 0.0 N/R N/R 3.67 3.77WS07 1.2 2.8 Nat 0.00 0.00 1.00 1.00 19.50 19.50 0.0 0.0 N/R N/R N/D 2.84
Comments:
NotesL.E.L. Lower Explosive Limit (100% L.E.L.'= 5% Flammable Gas) Highlighted cell for following conditions:N.D. Not Detected a. Methane ≥1% v/vN.R. Not Recorded b. Carbon Dioxide ≥5% v/vPID Photo-Ionising Detector MG Made Ground% By volume NS Natural Strata
Groundwater
Depth toGroundwater
(mbegl)
Total WellDepth (mbegl)
Response Zone (mbegl) Methane (%v/v) Carbon Dioxide (%v/v) Oxygen (%v/v) Gas Flow (l/h) PID Reading (ppm)
SteadyGas Data GFM430Tony Heron
Ground Gases
GAS MON TOM ROBSON
Eyes Farm, RocesterP7660Radmore Ltd.02 December 2016Wet
In-Situ Gas Monitoring Results
Project Name:Project Number:Client:Date:Weather:Atmospheric Pressure (mb): 1012Pressure Trend:Equipment:Operator:
Well ID
Top Base Strata Peak Steady Peak Steady Low Steady Peak Steady Peak Steady
WS01 1.0 5.0 Nat 0.00 0.00 1.00 1.00 19.50 19.50 0.0 0.0 N/R N/R 3.78 4.58WS02 0.7 1.7 Infill 0.00 0.00 0.00 0.00 20.50 20.50 0.0 0.0 N/R N/R N/D 1.60WS05 0.5 2.0 Infill 0.00 0.00 3.20 3.20 17.60 17.60 0.0 0.0 N/R N/R N/D 2.46WS06 1.0 3.5 Infill 0.00 0.00 4.50 4.50 4.10 4.10 0.0 0.0 N/R N/R 3.60 3.75WS07 1.2 2.8 Nat 0.00 0.00 1.50 1.50 18.50 18.50 0.0 0.0 N/R N/R N/D 2.85
Comments:
NotesL.E.L. Lower Explosive Limit (100% L.E.L.'= 5% Flammable Gas) Highlighted cell for following conditions:N.D. Not Detected a. Methane ≥1% v/vN.R. Not Recorded b. Carbon Dioxide ≥5% v/vPID Photo-Ionising Detector MG Made Ground% By volume NS Natural Strata
Groundwater
Depth toGroundwater
(mbegl)
Total WellDepth (mbegl)
Response Zone (mbegl) Methane (%v/v) Carbon Dioxide (%v/v) Oxygen (%v/v) Gas Flow (l/h) PID Reading (ppm)
FallingGas Data GFM430Liam Press
Ground Gases
Eyes Farm, RocesterP7660Radmore Ltd.12 December 2016Wet
In-Situ Gas Monitoring Results
Project Name:Project Number:Client:Date:Weather:Atmospheric Pressure (mb): 1019Pressure Trend:Equipment:Operator:
Well ID
Top Base Strata Peak Steady Peak Steady Low Steady Peak Steady Peak Steady
WS01 1.0 5.0 Nat 0.00 0.00 1.00 1.00 20.60 20.60 0.0 0.0 N/R N/R 3.83 4.70WS02 0.7 1.7 Infill 0.00 0.00 7.60 7.60 12.60 12.60 0.0 0.0 N/R N/R N/D 1.75WS05 0.5 2.0 Infill 0.00 0.00 5.30 5.30 13.60 13.60 0.0 0.0 N/R N/R N/D 2.50WS06 1.0 3.5 Infill 0.00 0.00 3.70 3.70 11.80 11.80 0.0 0.0 N/R N/R 3.65 3.75WS07 1.2 2.8 Nat 0.00 0.00 1.20 1.20 20.70 20.70 0.0 0.0 N/R N/R N/D 2.83
Comments:
NotesL.E.L. Lower Explosive Limit (100% L.E.L.'= 5% Flammable Gas) Highlighted cell for following conditions:N.D. Not Detected a. Methane ≥1% v/vN.R. Not Recorded b. Carbon Dioxide ≥5% v/vPID Photo-Ionising Detector MG Made Ground% By volume NS Natural Strata
Groundwater
Depth toGroundwater
(mbegl)
Total WellDepth (mbegl)
Response Zone (mbegl) Methane (%v/v) Carbon Dioxide (%v/v) Oxygen (%v/v) Gas Flow (l/h) PID Reading (ppm)
FallingGas Data LMSXiLiam Press
Ground Gases
Eyes Farm, RocesterP7660Radmore Ltd.06 January 2017Wet
In-Situ Gas Monitoring Results
Project Name:Project Number:Client:Date:Weather:Atmospheric Pressure (mb): 1023Pressure Trend:Equipment:Operator:
Well ID
Top Base Strata Peak Steady Peak Steady Low Steady Peak Steady Peak Steady
WS01 1.0 5.0 Nat 0.00 0.00 1.20 1.20 18.80 18.80 0.0 0.0 N/R N/R 3.76 4.66WS02 0.7 1.7 Infill 0.00 0.00 7.50 7.50 12.20 12.20 0.0 0.0 N/R N/R N/D 1.75WS05 0.5 2.0 Infill 0.00 0.00 6.10 6.10 10.50 10.50 0.0 0.0 N/R N/R N/D 2.34WS06 1.0 3.5 Infill 0.00 0.00 0.30 0.30 20.00 20.00 0.0 0.0 N/R N/R 3.54 3.74WS07 1.2 2.8 Nat 0.00 0.00 1.70 1.70 18.70 18.70 0.0 0.0 N/R N/R N/D 2.85
Comments:
NotesL.E.L. Lower Explosive Limit (100% L.E.L.'= 5% Flammable Gas) Highlighted cell for following conditions:N.D. Not Detected a. Methane ≥1% v/vN.R. Not Recorded b. Carbon Dioxide ≥5% v/vPID Photo-Ionising Detector MG Made Ground% By volume NS Natural Strata
Groundwater
Depth toGroundwater
(mbegl)
Total WellDepth (mbegl)
Response Zone (mbegl) Methane (%v/v) Carbon Dioxide (%v/v) Oxygen (%v/v) Gas Flow (l/h) PID Reading (ppm)
RisingGas Data GFM430Tony Heron
Ground Gases
Monitoring carried out by Wayne Barry.
Eyes Farm, RocesterP7660Radmore Ltd.17 January 2017Wet
In-Situ Gas Monitoring Results
Project Name:Project Number:Client:Date:Weather:Atmospheric Pressure (mb): 996Pressure Trend:Equipment:Operator:
Well ID
Top Base Strata Peak Steady Peak Steady Low Steady Peak Steady Peak Steady
WS01 1.0 5.0 Nat 0.00 0.00 0.00 0.00 21.00 21.00 0.0 0.0 NR NR 3.72 4.68WS02 0.7 1.7 Infill 0.00 0.00 0.00 0.00 21.00 21.00 0.0 0.0 NR NR ND 1.73WS05 0.5 2.0 Infill 0.00 0.00 0.00 0.00 20.90 20.90 0.0 0.0 NR NR ND 2.50WS06 1.0 3.5 Infill 0.00 0.00 0.00 0.00 20.90 20.90 0.0 0.0 NR NR 3.52 3.75WS07 1.2 2.8 Nat 0.00 0.00 2.30 2.30 19.00 19.00 0.0 0.0 NR NR ND 2.86
Comments:
NotesL.E.L. Lower Explosive Limit (100% L.E.L.'= 5% Flammable Gas) Highlighted cell for following conditions:N.D. Not Detected a. Methane ≥1% v/vN.R. Not Recorded b. Carbon Dioxide ≥5% v/vPID Photo-Ionising Detector MG Made Ground% By volume NS Natural Strata
Groundwater
Depth toGroundwater
(mbegl)
Total WellDepth (mbegl)
Response Zone (mbegl) Methane (%v/v) Carbon Dioxide (%v/v) Oxygen (%v/v) Gas Flow (l/h) PID Reading (ppm)
RisingGas Data LMSXiDave Evans
Ground Gases
Eyes Farm, RocesterP7660Radmore Ltd.30 January 2017Wet
