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Email: [email protected]

Land at Heath Road

Coxheath, Maidstone, Kent ME17 4EF

Flood Risk Assessment

Document Ref: SJC/615809/JRC Prepared: James Calvert

Revision: 2 Principal Engineer

Date: 24 July 2015

Checked: Steve Cox

Director

Land at Heath Road, Coxheath © MLM Consulting Engineers Limited Flood Risk Assessment

615809-REP-CIV-FRA

Project Revision Sheet

Revision

No Date Status Changes Author Approved

- 20/02/14 First

Issue N/A

James

Calvert

Steve

Cox

1 27/02/15 Revised Surface water drainage

strategy amended. JRC SJC

2 24/07/15 Revised Updated with infiltration

test results

JRC SJC


615809-REP-CIV-FRA

Contents

Page

1 Introduction 1

2 Site Description 2

3 Flood Risk 3

4 Surface Water Drainage 5

5 Conclusions 7


615809-REP-CIV-FRA

Appendices

Appendix A – Existing Site

MLM drawing 615809/100 – Site Location Plan

Environment Agency Online Flood Map

Appendix B – Proposed Site

CB2 Architecture Drawing 1208/2 Site Plan


Appendix C – Surface Water Drainage

Greenfield Run-off Calculations

Microdrainage Calculations – Initial soakaway sizing

Appendix D – Southern Water Asset Plans

Appendix E – Soakaway Testing Results

MLM Letter dated 11 February 2015 – Soakaway Infiltration Tests

MLM Letter dated 1 July 2015 – Preliminary Borehole Soakaway Infiltration Tests


615809-REP-CIV-FRA Page 1

1 Introduction

1.1 MLM Consulting Engineers Ltd is acting on behalf of Mr M J Older in the

preparation of a Flood Risk Assessment (FRA) for the proposed residential

development of land at Heath Road, Coxheath, Maidstone, Kent ME17 4EF.

1.2 The site is shown on the Environment Agency (EA) flood map to lie in Flood

Zone 1 (the low probability flood area) and is not considered to be at risk

of flooding from the sea or main watercourses. This FRA primarily focuses

on the surface water drainage strategy for the site but also addresses flood

risk from other sources of flooding.

1.3 This report has been prepared for the sole use of Mr M J Older and the

contents should not be relied upon by others without the express written

authority of MLM Consulting Engineers Ltd. If any unauthorised third party

makes use of this report they do so at their own risk and MLM owes them

no duty of care or skill.

1.4 This report has been completed in accordance with the National Planning

Policy Framework (NPPF) and its accompanying Planning Practice Guidance

(PPG).

1.5 Revision 1 of this report addresses issues raised by the EA contained within

the Planning Committee Report. This report includes details of

permeability tests undertaken at the site and a revised surface water

drainage strategy for the proposed development. This explains how

surface water from the development can be managed and discharged to a

watercourse without increased off site flood risk.

1.6 Revision 2 of this report includes an update following borehole infiltration

tests to determine the permeability of the underlying bedrock. The tests

were undertaken to address the EA concern regarding the discharge of

surface water run-off to the River Medway and the potential increase in

flood risk associated with the river.



2 Site Description

Existing Site

2.1 The site is located to the north of Heath Road to the north west of

Coxheath village centre. The site is approximately centred on Ordnance

Survey grid reference 573780, 151425. The site covers an area of

approximately 2.4 ha.

2.2 The site consists of an area of woodland and scrub, characterised by small

trees and bushes with an open grassed area to the northern extent of the

site. The B2163 Heath Road lies to the immediate south of the site with

residential properties of Whitebeam Drive to the east. To the north and

west of the site are further areas of woodland and scrub with residential

properties of Fairhurst Drive to the north-west corner of the development.

2.3 The site falls from south to north with a level difference between Heath

Road and the northern boundary of the site in the region of 5 m as shown

on Ordnance Survey (OS) mapping. There is no topographical survey of

the site available however level contours on OS mapping show that the site

falls from approximately 120 mAOD in the south to 115 mAOD in the

north.

Proposed Site

2.4 It is proposed to develop the site to provide 55 residential units together

with a new access off Heath Road.



3 Flood Risk

Tidal and Fluvial

3.1 According to the web based flood map the site lies in Flood Zone 1 (the low

probability flood area). The site is situated at a level of more than 100 m

above sea level. The site is not at risk of flooding from this source.

Minor Watercourse

3.2 There are no watercourses within the vicinity of the development. The

closest watercourse, the River Medway, lies approximately 2 km to the

north east of the site. The site is not at risk of flooding from this source.

Surface Water

3.3 To the south of the site lies Heath Road and residential development.

Wherever development has decreased the permeability of the soils through

the use of impermeable surfacing there is an increased risk of surface

water run-off. Heath Road falls from the east for approximately 200 m and

from the west for approximately 100 m. The access roads to the

residential development to the south also fall towards the site. Surface

water run-off from the highways could therefore run towards and onto the

site. Careful design of the on-site access road will be needed to ensure

that surface water run-off from this source will be directed away from the

proposed residential units towards the wood and scrubland to the north of

the site.

3.4 The EA ‘Risk of Flooding from Surface Water’ map shows that the site is at

risk of flooding from this source but that the risk is classified as low. With

careful consideration of finished levels on site to direct any surface water

run-off away from buildings the site will be at low risk of flooding from this

source.

Infrastructure Flooding

3.5 The Southern Water asset plans show that there are no sewers in Heath

Road to the south of the site. There is the possibility that there are sewers

or highway drains in Heath Road that could cause flooding in Heath Road if

they were to become blocked or their capacity exceeded. As discussed

above under Surface Water careful consideration should be given to

finished levels to direct any such flows away from buildings.

3.6 Figure 4.1 of the Maidstone Borough Strategic FRA shows that the site has

not previously been affected by flooding from this source. The site is

considered to be at low risk of flooding from this source.

Waterbodies

3.7 A review of OS mapping shows that there are no waterbodies in the vicinity

that could cause a flood risk to the site. The EA reservoir inundation map

shows that the site is not at risk of flooding from this source.



Groundwater

3.8 The underlying geology of the site is shown on British Geological Survey

mapping to be Head Deposits (Clay, Silt, Sands and Gravels) overlying

Hythe Formation (Sandstone and Limestone). Prior to the site walkover

there had been an extended period of wet weather, however there were no

signs of groundwater issuing at the site. Figure 4.1 of the Maidstone

Borough Strategic FRA shows that the site has not had any reported

flooding incidents from groundwater. The site is considered to be at low

risk of flooding from this source.



4 Surface Water Drainage

4.1 The site is greenfield and is not surrounded by any ditches, it is therefore

likely that surface water either infiltrates into the underlying soils or

discharges as overland flow to adjacent land to the north of the site.

4.2 Greenfield run-off rates have been calculated for the site using the method

described in report W5-074A ‘Preliminary Rainfall Run-off Management for

Developments’. The greenfield rates calculated are as follows:

Return Period

(Yrs)

Greenfield Run-off

Rate (l/s/ha)

Greenfield Run-off

Rate (l/s)

1 1.42 3.40

30 3.84 9.22

100 5.28 12.67

4.3 The site is underlain by Hythe sandstone and Limestone which may be

suitably permeable for the utilisation of soakaways to discharge surface

water run-off from the development. Intrusive site investigation, including

permeability testing, was undertaken to determine whether infiltration is

feasible.

4.4 MLM undertook shallow permeability tests at the site on 3 February 2015,

the results of which show that despite the presence of sandstone and

limestone in the underlying geology, the soils are not of sufficient

permeability for infiltration drainage. The results of the testing are

included in Appendix E of this report.

4.5 Deep borehole soakaway tests were undertaken on 18 June 2015; two

borehole locations were identified and falling head and constant head tests

were undertaken.

4.6 At borehole 1, located in the north of the site, a falling head test was

undertaken at 10 m below ground level (bgl). This did not show any

significant fall in water within the borehole. At 12-12.5 m bgl a void was

encountered and a constant head test was undertaken. Water was

discharged into the borehole at 16 l/s however this rate was not sufficient

to induce a head of water in the borehole and the test was abandoned after

11 minutes. Finally the borehole was progressed to 20 m bgl where a

second falling head test was undertaken. The borehole was filled to 12.5

m bgl; there was no fall in water level in this part of the borehole.

4.7 At borehole 2, two falling head tests were undertaken at depths of 7 m and

20 m bgl. There was no noticeable fall in head in either of the tests.

4.8 The extent of the void in borehole 1 was not proven due to the limited

number of boreholes. However the discharge rate of 16 l/s into the

borehole shows that the capacity of the void to accept surface water run-

off is significant. It is proposed to discharge surface water run-off into the

void, potentially at the location of borehole 1, but also at other areas

identified during further borehole investigations that could be undertaken

prior to detailed design. The layout of the site should be developed around

areas where the void is shown to be present to enable attenuation to be

provided in areas adjacent to the boreholes/void.



4.9 Microdrainage calculations; see Appendix C, show that an attenuation

storage volume in the region of 905 m3 would be required based on

discharge of surface water run-off at 16 l/s, based on a single borehole

discharge location. This is an estimate for the total volume of attenuation

required for the whole site based on an assumed 60% impermeable

surfacing of the developed site, i.e. 14400 m2. If other locations are

identified where discharge to the void can be made then the required

volume of attenuation would be lower.

4.10 The SuDS hierarchy requires that surface water run-off is controlled and

preferably re-used wherever possible. In the event that it cannot be re-

used it should be disposed of to a receptor in the order described in

Building Regulations Part H and CIRIA 697 The SuDS Manual:

• via infiltration,

• to watercourse, and finally,

• to sewers.

4.11 In accordance with good practice finished floor levels of any buildings

should be raised above surrounding ground levels by a minimum of 150

mm in order that any flooding from the surface water run-off, or from

other sources as described in section 3, would not cause internal flooding

of the buildings. Flow routes should be designed so that in the event of

failure of the surface water drainage network flood water would be routed

away from / around buildings.



5 Conclusions

5.1 The site is shown to lie in Flood Zone 1 on the EA web based flood map, it

does not lie in a reservoir inundation zone. From a review of the

Maidstone Strategic FRA and the topography of the site it is concluded that

there are no other significant flood risks to the site and that any flood risk

to the site can be managed through the careful design of finished levels on

site. Particular attention should be given in the design to the potential for

surface run-off to enter the site via the proposed access road. Overland

flood flow routes should be incorporated into the design.

5.2 Permeability testing at the site has shown that discharge of surface water

run-off via infiltration to the void within the northern part of the site is

feasible. Discharge at a rate of 16 l/s has been shown to be feasible which

would mean that the site would require an approximate attenuation

volume of 905 m3 for the 100 year return period rainfall event inclusive of

climate change.

5.3 The site is therefore not at significant risk of flooding and will not cause an

increase in off-site flood risk.


Appendix A – Existing Site

MLM drawing 615809/100 – Site Location Plan

Environment Agency Online Flood Map

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Appendix B – Proposed Site



Revision Notes:

Revision Notes00/00/2010P1CB2

38 DITTON PLACE, DITTON, AYLESFORD, KENT, ME20 6SXT: 01732 875015 M: 07913 158707 E: [email protected]

© CB2 ARCHITECTURE LTD

DESIGNS THAT ADD VALUE

CB2 ARCHITECTURE LTDDrawing:

Project & Client:

Project Ref:

Date:

Scale @ A3:

Purpose of issue:Drawing Ref: Revision:

1:500

NOV 2013

31208

LAND ADJACENT TO HEATH ROAD,COXHEATH

SITE PLAN


Appendix C – Proposed Site

Greenfield Run-off Calculations

Microdrainage Calculations – Initial soakaway sizing

MLM Consulting Engineers Page 1

North Lodge 615809 Heath Road

25 London Road Coxheath

Ipswich IP1 2HF Attenuation Crates

Date 24.07.15 Designed by J Calvert

File 615809-CALC-CIV-MDCalc-... Checked by

XP Solutions Source Control 2014.1.1

Summary of Results for 100 year Return Period (+30%)

©1982-2014 XP Solutions

Half Drain Time : 466 minutes.

Storm

Event

Max

Level

(m)

Max

Depth

(m)

Max

Infiltration

(l/s)

Max

Control

(l/s)

Max

Σ Outflow

(l/s)

Max

Volume

(m³)

Status

15 min Summer 8.909 0.509 0.0 16.0 16.0 546.9 O K30 min Summer 8.971 0.571 0.0 16.0 16.0 613.4 O K60 min Summer 9.031 0.631 0.0 16.0 16.0 677.4 O K120 min Summer 9.076 0.676 0.0 16.0 16.0 725.9 O K180 min Summer 9.088 0.688 0.0 16.0 16.0 738.1 O K240 min Summer 9.082 0.682 0.0 16.0 16.0 732.5 O K360 min Summer 9.050 0.650 0.0 16.0 16.0 697.3 O K480 min Summer 9.016 0.616 0.0 16.0 16.0 661.5 O K600 min Summer 8.990 0.590 0.0 16.0 16.0 633.3 O K720 min Summer 8.968 0.568 0.0 16.0 16.0 609.8 O K960 min Summer 8.944 0.544 0.0 16.0 16.0 583.7 O K1440 min Summer 8.893 0.493 0.0 16.0 16.0 528.8 O K2160 min Summer 8.813 0.413 0.0 16.0 16.0 443.8 O K2880 min Summer 8.738 0.338 0.0 16.0 16.0 363.3 O K4320 min Summer 8.584 0.184 0.0 16.0 16.0 198.1 O K5760 min Summer 8.483 0.083 0.0 16.0 16.0 89.1 O K7200 min Summer 8.423 0.023 0.0 16.0 16.0 25.1 O K8640 min Summer 8.403 0.003 0.0 16.0 16.0 2.8 O K10080 min Summer 8.402 0.002 0.0 16.0 16.0 2.0 O K

15 min Winter 8.973 0.573 0.0 16.0 16.0 614.9 O K

Storm

Event

Rain

(mm/hr)

Flooded

Volume

(m³)

Discharge

Volume

(m³)

Time-Peak

(mins)

15 min Summer 209.120 0.0 564.2 1930 min Summer 119.493 0.0 644.6 3360 min Summer 68.280 0.0 736.8 64120 min Summer 39.016 0.0 842.4 122180 min Summer 28.123 0.0 910.6 182240 min Summer 22.294 0.0 962.4 242360 min Summer 16.070 0.0 1041.6 352480 min Summer 12.739 0.0 1100.6 404600 min Summer 10.639 0.0 1148.6 464720 min Summer 9.182 0.0 1190.4 524960 min Summer 7.412 0.0 1280.1 6621440 min Summer 5.481 0.0 1421.1 9362160 min Summer 4.053 0.0 1586.8 13402880 min Summer 3.272 0.0 1704.1 17284320 min Summer 2.346 0.0 1834.3 24605760 min Summer 1.853 0.0 1904.9 31127200 min Summer 1.543 0.0 1986.1 37448640 min Summer 1.328 0.0 2064.3 435210080 min Summer 1.171 0.0 2095.8 5208

15 min Winter 209.120 0.0 632.2 19








Summary of Results for 100 year Return Period (+30%)


Storm

Event

Max

Level

(m)

Max

Depth

(m)

Max

Infiltration

(l/s)

Max

Control

(l/s)

Max

Σ Outflow

(l/s)

Max

Volume

(m³)

Status

30 min Winter 9.044 0.644 0.0 16.0 16.0 691.8 O K60 min Winter 9.115 0.715 0.0 16.0 16.0 767.8 O K120 min Winter 9.173 0.773 0.0 16.0 16.0 829.9 O K180 min Winter 9.194 0.794 0.0 16.0 16.0 851.9 O K240 min Winter 9.197 0.797 0.0 16.0 16.0 855.2 O K360 min Winter 9.177 0.777 0.0 16.0 16.0 834.2 O K480 min Winter 9.141 0.741 0.0 16.0 16.0 795.6 O K600 min Winter 9.099 0.699 0.0 16.0 16.0 750.5 O K720 min Winter 9.071 0.671 0.0 16.0 16.0 720.4 O K960 min Winter 9.036 0.636 0.0 16.0 16.0 682.4 O K1440 min Winter 8.954 0.554 0.0 16.0 16.0 594.3 O K2160 min Winter 8.826 0.426 0.0 16.0 16.0 457.6 O K2880 min Winter 8.708 0.308 0.0 16.0 16.0 330.2 O K4320 min Winter 8.493 0.093 0.0 16.0 16.0 99.4 O K5760 min Winter 8.403 0.003 0.0 16.0 16.0 2.8 O K7200 min Winter 8.401 0.001 0.0 16.0 16.0 2.0 O K8640 min Winter 8.401 0.001 0.0 16.0 16.0 2.0 O K10080 min Winter 8.401 0.001 0.0 16.0 16.0 2.0 O K

Storm

Event

Rain

(mm/hr)

Flooded

Volume

(m³)

Discharge

Volume

(m³)

Time-Peak

(mins)

30 min Winter 119.493 0.0 721.9 3360 min Winter 68.280 0.0 825.6 62120 min Winter 39.016 0.0 944.2 120180 min Winter 28.123 0.0 1019.8 178240 min Winter 22.294 0.0 1077.7 236360 min Winter 16.070 0.0 1166.3 348480 min Winter 12.739 0.0 1232.2 454600 min Winter 10.639 0.0 1286.1 502720 min Winter 9.182 0.0 1331.9 564960 min Winter 7.412 0.0 1434.2 7201440 min Winter 5.481 0.0 1590.8 10222160 min Winter 4.053 0.0 1775.2 14482880 min Winter 3.272 0.0 1916.6 18444320 min Winter 2.346 0.0 2057.5 25085760 min Winter 1.853 0.0 2133.8 29127200 min Winter 1.543 0.0 2225.5 39448640 min Winter 1.328 0.0 2287.1 381610080 min Winter 1.171 0.0 2327.3 5424








Rainfall Details


Rainfall Model FEHReturn Period (years) 100

Site Location GB 574250 152000 TQ 74250 52000C (1km) -0.024D1 (1km) 0.303D2 (1km) 0.366D3 (1km) 0.290E (1km) 0.317F (1km) 2.503

Summer Storms YesWinter Storms YesCv (Summer) 0.750Cv (Winter) 0.840

Shortest Storm (mins) 15Longest Storm (mins) 10080

Climate Change % +30

Time Area Diagram

Total Area (ha) 1.440

Time

From:

(mins)

To:

Area

(ha)

0 4 1.440








Model Details


Storage is Online Cover Level (m) 10.000

Cellular Storage Structure

Invert Level (m) 8.400 Safety Factor 2.0Infiltration Coefficient Base (m/hr) 0.00000 Porosity 0.95Infiltration Coefficient Side (m/hr) 0.00000

Depth (m) Area (m²) Inf. Area (m²) Depth (m) Area (m²) Inf. Area (m²)

0.000 1130.0 0.0 0.801 0.0 0.00.800 1130.0 0.0

Pump Outflow Control

Invert Level (m) 8.400

Depth (m) Flow (l/s) Depth (m) Flow (l/s)

0.001 16.0000 1.600 16.0000


Appendix D – Southern Water Asset Plans

Southern Water Southern House Capstone Road Chatham Kent ME5 7QA www.southernwater.co.uk Southern Water Services Ltd Registered Office: Southern House Yeoman Road Worthing BN13 3NX Registered in England No. 2366670

Your Ref Our Ref Date Contact

[email protected] Fax 01634 844514 DX:400450 Chatham 5

Attention: Dear Sirs

Further to your recent enquiry regarding the provision of Southern Water apparatus record extracts for the above location. Please be aware that there are areas within our region in which there are neither sewers nor water mains. Similarly, whilst the enclosed extract may indicate the approximate location of our apparatus in the area of interest, it should not be relied upon as showing that further infrastructure does not exist and may subsequently be found following site investigation. Therefore actual positions of the disclosed (and any undisclosed) infrastructure should be determined on site, because Southern Water does not accept any responsibility for inaccuracy or omission regarding the enclosed plan and accordingly it should not be considered to be a definitive document. I confirm payment of the appropriate fee in the sum of £ The breakdown of costs is as follows: -

Provision of record extracts £

VAT @ 20.0% £

VAT Registration Number 543 9000 63

Should you require any additional information regarding this matter please contact this office at the address given at the foot of this letter. Yours faithfully Land Search Department

MLM Consulting Engineers LimitedNorth Lodge 25London RoadIpswichSuffolkIP1 2HF

615809

168684

18 February 2014

James Calvert

Provision of Public Sewer Main Record Extracts – VAT ReceiptLand at Heath Road, Coxheath

48.00

40.00

8.00

mailto:[email protected]


Appendix E – Soakaway Testing Results

MLM Letter dated 11 February 2015 – Soakaway Infiltration Tests

MLM Letter dated 1 July 2015 – Preliminary Borehole Soakaway Infiltration Tests

MLM Consulting Engineers Limited 01223 632800 Building 7200, Cambridge Research Park, Cambridge, CB25 9TL 01223 815630

Our Ref: 772596-LET-ENV-001 11 February 2015

Mr Chris Atkinson 9 St. Luke’s Avenue Maidstone Kent ME14 5AN Dear Chris Re: Land off Heath Road, Coxheath, near Maidstone, Kent, ME17 4EQ Soakaway Infiltration Tests

Further to your recent instruction we are pleased to provide the results of the additional soakaway infiltration tests undertaken at the above site. 1 Background

This report has been prepared for Chris Atkinson, to describe the results gathered for the five number soakaway tests for the proposed residential development at the above site. The investigation and assessment will be used to assist in the preparation of a drainage strategy for the new development. The site is located off Heath Road in Coxheath, near Maidstone Kent and currently comprises a rectangular area of part wooded/part open ground flanked by residential developments. The site is used by the general public and pedestrian access comprising footpaths are present across the site linking the residential areas and the main road to the south. A gated access and sty is present at the south western corner off Heath Road. Observed geology from the five trial pits was firm cohesive silty clay consistent with Head Deposits, overlying weathered sandstone considered to be the Hythe Beds. This investigation and assessment has been undertaken to meet the requirements of the following:

• Building Regulations Approved Document C. • BS EN 1997-2: 2007 and, where there is no conflict is in general accordance

with the reporting requirements of BS5930:1999+A2:2010. • AGS Guidelines for Combined Geo-environmental and Geotechnical

Investigations 2000. 2 Field Work

Soakaway infiltration testing was undertaken at five positions (SA1 to SA5) on 03/02/2015. All five locations (SA1 to SA5) were selected by MLM Environmental engineers in consultation with MLM drainage engineers and the Client who arranged the access and the clearing of vegetation. The soakaway test positions are shown on Figure 1. Each position was initially cleared of underground services using a CAT and ground probing radar. The test pits were then excavated using a back acting excavator with a width of 0.8m and lengths of between 2.10m and 2.60mm.

Page: 3 Our Ref.: 772596-LET-ENV-001 11 February 2015 Mr Chris Atkinson

The pits were excavated down to the top of a weathered sandstone rock unit of the Hythe Beds. Once completed, the trial pit sides were trimmed to create as regular sided pit as possible. Soakaway infiltration testing was undertaken in general accordance with BRE Digest 365 (2007). Clean water was added to each pit from a bowser and the rate at which the water level fell measured from a datum point.

On completion of the testing, all pits were emptied of any remaining water, backfilled with arisings compacted in layers using the excavator bucket.

3 Test Results

The test results are presented in Appendix A attached along with infiltration rates calculated in accordance with BRE 365.

The ground conditions identified in the pits were as follows:

Depth to base Stratum 0.10m – 0.50m Soft dark brown silty CLAY. Frequent rootlets. (Topsoil)

0.70m (SA1) Black slightly gravelly fine to coarse ashy sand. Gravel is fine

to medium, angular to sub-rounded of brick. Occasional cobbles of brick (Made Ground).

0.65m – 2.60m

Firm orange silty CLAY.

0.65m – 1.10m

Soft light orangish brown silty slightly sandy CLAY. Sand is fine to coarse.

2.60m (SA1) Soft light orangish brown very sandy slightly gravelly SILT. Gravel is fine to medium, angular to sub-rounded. Sand is fine to coarse. Occasional cobbles of sandstone.

Top encountered between depths of 1.45 and 2.60m bgl.

Weak weathered SANDSTONE.

Each pit was filled to a depth of between 0.43m and 0.92m bgl. The pit sides remained stable throughout excavation and testing. Infiltration rates calculated from the testing were as follows:

Test Position Test Depth Infiltration Stratum Infiltration Rate1

SA1 0.59m Firm orange silty CLAY Test failed SA2 0.43m Firm orange silty CLAY Test failed SA3 0.92m Firm orange silty CLAY Test failed SA4 0.88m Firm orange silty CLAY Test failed SA5 0.55m Firm orange silty CLAY Test failed 1. Infiltration rate calculated from test.

The tests in all of the pits were left to run for a minimum of 120 minutes (2 hours) but, in this time, the water level failed to fall sufficiently for the infiltration rate to be calculated using the method of BRE365.

Page: 3 Our Ref.: 772596-LET-ENV-001 11 February 2015 Mr Chris Atkinson

The test results of SA1 and SA5 have been extrapolated to provide an estimate of the infiltration rate and this suggests an infiltration rate of the order of 10-9 - 10-

8m/s which corresponds to poor drainage potential. Infiltration for tests SA2–SA4 was so low that extrapolated results cannot be easily calculated and on this basis the results of SA2–SA4 suggest an infiltration rate of 10-9m/s or lower indicating negligible permeability. Based on the extrapolation of the test results in SA1 and SA5, the estimated times required for the water to fall to a sufficient level to allow the soil infiltration rates to be calculated (based on BRE Digest 365) was in the order of 18 to 27 hours (SA1 and SA5 respectively). It was not possible to calculate the soil infiltration rates for tests SA2–SA4 due to extremely low infiltration.

4 Conclusions

Based on the soakaway tests, undertaken by MLM, it is clear that the infiltration rates in the upper 1m of the ground surface do not vary greatly across the site due to the consistency of the nature of the soil across the site. The presence of the firm orange silty clay indicates likely infiltration rates of 10-9m/s or lower. The other soils found in the area also have a high content of clays and silts which will also slow the infiltration rate. The permeability of the underlying sandstone is also evidently very low and it is expected that this is because any fissures or discontinuities are clay filled. Based on the investigations undertaken, design soil infiltration rates within firm orange silty clay 10-8m/s–10-9m/s. An overall design value of 10-9m/s may be prudent for the site.

We trust that the above meets with your present requirements. Should you should have any further queries please do not hesitate to contact the undersigned. Yours sincerely

Mike Williams Enc. Soakaway test results

Figure 1 Soakaway Test Locations

Project Land of Heath Road

Site Location Plan

Job No.

772596

Figure No.

1

S

I

T

E

N

TP1/SA1

TP2/SA2

TP3/SA3

TP4/SA4

TP5/SA5

Soakaway Test Results

SOAKAWAY TEST RESULTSBased on BRE Digest 365: Soakaway Design (2007)

Project Name: Land of Heath Road

Location: Land of Heath Road, Coxheath ME17 4 WQ

Project Ref: 772596

Test Location: TP5

Readings: Trial Pit Dimensions (m)

Length

Width

0 0.55 Depth

1 0.57

2 0.58 0.55

3 0.58

4 0.58 Ground Conditions:

5 0.58 GL-0.25

7 0.58 0.25-0.65

10 0.58 0.65-1.45

20 0.58 >1.45

30 0.58

40 0.59 No

50 0.59

60 0.59 Remarks:

70 0.60 Frozen ground with light snow covering up until 13:00

80 0.60

90 0.61

100 0.61

110 0.62

120 0.62

Fill Porosity 0.35

V p75 - 25 0.79

Revised V p75 - 25 0.28

α p50 4.46

tp75 - 25

ƒ

ƒ Practically impermeable

Soil Infiltration Rate (m/sec) Test Failed

Time

(mins)

Water Level

(m bgl)

2.20

0.80

1.45

Assumed Invert Level (m bgl)

TS

Head Deposits - Silty sandy Clay

Head Deposits - Silty Clay

Hythe Beds - Sandstone

Was trial pit filled with gravel (Yes/No):

Soil Infiltration Rate (m/sec) ƒV p75 - 25

α p50 x t p75 - 25

Assumed porosity of granular fill material based on CIRIA 156 (%)

Effective depth storage volume of water in the trial pit between 75% and 25% effective

depth

Reduced effective storage volume as a result of gravel fill

The internal surface area of the trial pit up to 50% effective depth and including the base

area

The time for the water level to fall from 75% to 25% effective depth

Soil Infiltration Rate (m/sec) N/A

Test Failed

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

0 10 20 30 40 50 60 70 80 90 100 110 120 130

Water Level (m

bgl)

Time (mins)

Fall in Water over Time

Time

75% Effective Depth

25% Effective Depth




Project Ref: 772596

Test Location: TP2


Length

Width

0 0.43 Depth

1 0.44

2 0.44 0.43

3 0.44


5 0.44 GL-0.1

7 0.44 0.1-1.7

10 0.44 >1.7

20 0.44

30 0.44

40 0.44 No

50 0.44

60 0.44 Remarks:


80 0.44

90 0.44

100 0.44

110 0.44

120 0.44

Fill Porosity 0.35

V p75 - 25 1.27

Revised V p75 - 25 0.44

α p50 6.19

tp75 - 25

ƒ

ƒ Practically impermeable Test Failed


Time

(mins)

Water Level

(m bgl)

2.50

0.80

1.70


Topsoil


Hythe Beds - Weathered sandstone



α p50 x t p75 - 25



depth



area



0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

0 10 20 30 40 50 60 70 80 90 100 110 120 130

Water Level (m

bgl)

Time (mins)


Time

75% Effective Depth

25% Effective Depth




Project Ref: 772596

Test Location: TP3


Length

Width

0 0.92 Depth

1 0.93

2 0.93 0.92

3 0.93


5 0.94 GL-0.5

7 0.94 0.5-1.1

10 0.94 1.1-2.6

20 0.94 >2.6

30 0.94

40 0.94 No

50 0.94

60 0.95 Remarks:


80 0.95

90 0.95

100 0.95

110 0.95

120 0.95

Fill Porosity 0.35

V p75 - 25 1.61

Revised V p75 - 25 0.56

α p50 7.30

tp75 - 25

ƒ



Time

(mins)

Water Level

(m bgl)

2.40

0.80

2.60


Topsoil



Hythe Beds - Weathered sandstone



α p50 x t p75 - 25



depth



area



Test Failed

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

1.80

2.00

2.20

2.40

0 10 20 30 40 50 60 70 80 90 100 110 120 130

Water Level (m

bgl)

Time (mins)


Time

75% Effective Depth

25% Effective Depth




Project Ref: 772596

Test Location: TP4


Length

Width

0 0.88 Depth

1 0.88

2 0.88 0.88

3 0.88


5 0.88 GL-0.5

7 0.89 0.5-0.7

10 0.89 0.7-2.4

20 0.89 >2.4

30 0.89

40 0.90 No

50 0.90

60 0.90 Remarks:


80 0.90

90 0.90

100 0.90

110 0.90

120 0.90

Fill Porosity 0.35

V p75 - 25 1.58

Revised V p75 - 25 0.55

α p50 7.25

tp75 - 25

ƒ



Time

(mins)

Water Level

(m bgl)

2.60

0.80

2.40


TS






α p50 x t p75 - 25



depth



area



Test Failed

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

1.80

2.00

2.20

0 10 20 30 40 50 60 70 80 90 100 110 120 130

Water Level (m

bgl)

Time (mins)


Time

75% Effective Depth

25% Effective Depth




Project Ref: 772596

Test Location: TP5


Length

Width

0 0.55 Depth

1 0.57

2 0.58 0.55

3 0.58


5 0.58 GL-0.25

7 0.58 0.25-0.65

10 0.58 0.65-1.45

20 0.58 >1.45

30 0.58

40 0.59 No

50 0.59

60 0.59 Remarks:


80 0.60

90 0.61

100 0.61

110 0.62

120 0.62

Fill Porosity 0.35

V p75 - 25 0.79

Revised V p75 - 25 0.28

α p50 4.46

tp75 - 25

ƒ



Time

(mins)

Water Level

(m bgl)

2.20

0.80

1.45


TS






α p50 x t p75 - 25



depth



area



Test Failed

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

0 10 20 30 40 50 60 70 80 90 100 110 120 130

Water Level (m

bgl)

Time (mins)


Time

75% Effective Depth

25% Effective Depth

Trial Pit Logs

Project:

Project ID:

Location:

Client:

ProjectEngineer:

Land off Heath Road

772596

Land off Heath Road, Coxheath

Mike Williams

Method:

Start:

Finish:

Level (mOD):

Co-ordinates:

TP

03/02/2015

03/02/2015

TP1

0.00 1:25

E -

N

Sheet 1 of 1

Logged by:

Notes:Shear strengths recorded using Pilicon Hand Shear Vane

Remarks

Terminated at 2.30m due to contact with weathered sandstone bedrock

Dimensions:

m

m

Stability:

Plant Used:

INSITU TEST/SAMPLING

De

pth

(m

)

Sa

mp

le

Ref. Strength

Shear(kPa)

STRATA

Level(mAOD)

-0.50

-0.70

-2.00

-2.30

Depth(m)

1

2

3

4

0.50

0.70

2.00

2.30

Leg

en

d

Description of Strata

TS: Soft dark brown silty CLAY. Frequent rootlets.TOPSOIL

MG: Black slightly gravelly fine to coarse Sand of ash. Gravel is fine to medium, angular to sub-rounded of brick. Occasional cobbles of brick.MADE GROUNDFirm orange slightly silty CLAY.Silty CLAY

Soft light orangish brown very sandy slightly gravelly SILT. Gravel is fine to medium, angular to sub-rounded. Sand is fine to coarse. Occasional cobbles of sandstone.Sandy gravelly cobbly SILT

End of trial pit at 2.30 m

Thic

kn

ess

(m)

0.50

0.20

1.30

0.30

Water(m)

Project:

Project ID:

Location:

Client:

ProjectEngineer:

Land off Heath Road

772596


Mike Williams

Method:

Start:

Finish:

Level (mOD):

Co-ordinates:

TP

03/02/2015

03/02/2015

TP2

0.00 1:25

E -

N

Sheet 1 of 1

Logged by:


Remarks


Dimensions:

m

m

Stability:

Plant Used:


De

pth

(m

)

Sa

mp

le

Ref. Strength

Shear(kPa)

STRATA

Level(mAOD)

-0.10

-1.70

Depth(m)

1

2

3

4

0.10

1.70

Leg

en

d


TS: Soft dark brown silty CLAY. Frequent rootlets.TOPSOILFirm orange silty CLAY.Silty CLAY


Thic

kn

ess

(m)

0.10

1.60

Water(m)

Project:

Project ID:

Location:

Client:

ProjectEngineer:

Land off Heath Road

772596


Mike Williams

Method:

Start:

Finish:

Level (mOD):

Co-ordinates:

TP

03/02/2015

03/02/2015

TP3

0.00 1:25

E -

N

Sheet 1 of 1

Logged by:


Remarks


Dimensions:

m

m

Stability:

Plant Used:


De

pth

(m

)

Sa

mp

le

Ref. Strength

Shear(kPa)

STRATA

Level(mAOD)

-0.50

-1.10

-2.60

Depth(m)

1

2

3

4

0.50

1.10

2.60

Leg

en

d


TS: Soft dark brown silty CLAY. Frequent rootlets.TOPSOIL

Soft light orangish brown silty slightly sandy CLAY. Sand is fine to coarse.Silty sandy CLAY

Firm orange mottled grey silty CLAYSilty CLAY


Thic

kn

ess

(m)

0.50

0.60

1.50

Water(m)

Project:

Project ID:

Location:

Client:

ProjectEngineer:

Land off Heath Road

772596


Mike Williams

Method:

Start:

Finish:

Level (mOD):

Co-ordinates:

TP

03/02/2015

03/02/2015

TP4

0.00 1:25

E -

N

Sheet 1 of 1

Logged by:


Remarks


Dimensions:

m

m

Stability:

Plant Used:


De

pth

(m

)

Sa

mp

le

Ref. Strength

Shear(kPa)

STRATA

Level(mAOD)

-0.50

-0.70

-2.40

Depth(m)

1

2

3

4

0.50

0.70

2.40

Leg

en

d


TS: Soft dark brown silty CLAY. Moderate rootlets.TOPSOIL


Firm orange mottled grey silty CLAYSilty CLAY


Thic

kn

ess

(m)

0.50

0.20

1.70

Water(m)

Project:

Project ID:

Location:

Client:

ProjectEngineer:

Land off Heath Road

772596


Mike Williams

Method:

Start:

Finish:

Level (mOD):

Co-ordinates:

TP

03/02/2015

03/02/2015TP5

0.00 1:25

E -

N

Sheet 1 of 1

Logged by:


Remarks


Dimensions:

m

m

Stability:

Plant Used:


De

pth

(m

)

Sa

mp

le

Ref. Strength

Shear(kPa)

STRATA

Level(mAOD)

-0.25

-0.65

-1.45

Depth(m)

1

2

3

4

0.25

0.65

1.45

Leg

en

d


TS: Soft dark brown silty CLAY. Moderate rootlets.TOPSOIL


Firm orange silty CLAY.Silty CLAY


Thic

kn

ess

(m)

0.25

0.40

0.80

Water(m)

MLM Consulting Engineers Limited Main Tel: 01233 610530 190 Eureka park, Upper Pemberton, Ashford, Kent, TN25 4AZ Main Fax: 01233 618299

V3

Our Ref: 772845-REP-ENV-001 1 July 2015

Chris Atkinson Consultant Town Planner 9 St. Luke’s Avenue Maidstone Kent ME14 5AN Dear Mr Atkinson Re: Land off Heath Road, Coxheath Preliminary Borehole Soakaway Infiltration Tests

This report has been prepared for Mr Michael Older (Client) who is proposing to develop the site at land off Heath Road, Coxheath for a residential end use. MLM Environmental (MLME) was commissioned to undertake soakage testing in deep boreholes to assist in the preparation of a drainage strategy for the site. The terms of reference for the work were set out in a letter by MLME ref. 772845-FEE-ENV-001 dated 28 May 2015. The scope of work was for the drilling of two rotary open hole bored boreholes to 20m and soakage testing at intervals in general accordance with the Kent Soakaway Design Guide to assess the viability of deep bored soakaways. 1 Background

MLM has been appointed as drainage engineers for the proposed residential development. To assist in the design of the drainage strategy MLME has carried out investigations to assess the viability of discharging surface water via deep bored soakaways. Prior to the current investigation five shallow trial pit (BRE365) soakage tests were undertaken in February 2015. This investigation revealed cohesive drift deposits (Head Deposits) overlying sandstone (Hythe Formation). All of the tests failed due to negligibly permeable strata and therefore it was concluded that shallow soakaways would not be a viable drainage option. The current investigation was instructed to assess the viability of deep bored soakaways as an alternative drainage option.

2 Site Description The site comprises a rectangular area of land bound by Heath Road to the south, residential development to the east and west and open access wooded land to the north. The site itself is undeveloped and comprises part wooded, part grassed open space which is currently open to the public.

Page: 2 Our Ref.: 772845-REP-ENV-001 Job Title: Land off Heath Road, Coxheath Date: 8 July 2015

3 Field Work

Two rotary open hole bored boreholes were drilled to 20m in two locations using a lorry mounted Hands England Rotary borehole rig. The borehole was progressed at a diameter of 0.15m for the entire length and cased to bedrock. The borehole locations were chosen on their accessibility and in consideration of the public, which had access to the site at the time of the investigation. The borehole locations are presented on the attached drawing ref. 772845-DWG-ENV-001. Prior to drilling, each position was initially cleared of underground services using a CAT and ground probing radar. A hand dug pit was also dug to 1.20m bgl at each location to check for near surface services. The boreholes were progressed using rotary open hole drilling methods using an air flush, except when voids were encountered where a foam flush was temporarily introduced to progress below the voids. Both boreholes were cased to bedrock. Initially a tri rock roller bit was used to progress through the upper sandstone bedrock, however progress significantly slowed on encountering harder limestone bedrock and the bit was exchanged for a down-the-hole (DTH) hammer bit. Infiltration testing was undertaken in general accordance with the Kent Highway Design Guide (2007). Clean water for the testing was provided via a 15,000 litre water tanker. The rate of discharge (not pumped) has been estimated at approximately 16 litres per second. Two types of infiltration test were attempted during the investigation; falling head test and constant rate test. During the falling head tests water was introduced to each borehole and the rate at which the water level fell measured from a datum point. During the constant head test water was introduced and the flow of water required to keep the water level at a constant depth in the borehole was measured. Further details of the testing is given in Section 4.

On completion of the testing, both boreholes were backfilled using clean granular arisings and pea gravel with a 1m bentonite seal installed from 1m bgl to ground level.

4 Geology

The site is underlain by superficial Head Deposits comprising sandy clays overlying bedrock of the Hythe Deposits (Sandstone and Limestone). In Kent Hythe Deposits have been widely used as deposits into which surface run off can be discharged. However, the soakage rate depends on the frequency of their fissures and their degree of openness.

Borehole Logs are presented in Appendix A.

The ground conditions identified in the boreholes were as follows:


BH1 (North)

Depth (m bgl) Stratum GL - 0.30 Orange brown clayey fine to coarse SAND (TOPSOIL) 0.30 – 1.50 Orange brown sandy CLAY with occasional gravel to cobble

sized sandstone (HEAD DEPOSITS) 1.50 - 7.00 Yellowish brown SANDSTONE with interbedded bands of

LIMESTONE (HYTHE FORMATION) 7.00 – 12.00 Strong bluish grey LIMESTONE (HYTHE FORMATION) 12.00 – 12.50 Voided Strata 12.50 – 20.00 Strong bluish grey LIMESTONE (HYTHE FORMATION)

* base not proven in this phase of investigation.

BH2 (South) Depth (m bgl) Stratum GL – 0.30 Orange brown clayey fine to coarse SAND (TOPSOIL) 0.30 – 2.80 Orange brown sandy slightly gravelly CLAY with rare

sandstone cobbles. (HEAD DEPOSITS) 2.80 – 5.50 Greenish brown clayey fine to coarse SANDSTONE (HYTHE

FORMATION) 5.50 – 20.00 Strong bluish grey LIMESTONE (HYTHE Formation)

* base not proven in this phase of investigation. The ground conditions encountered in the boreholes is consistent with the trial pits undertaken in the February 2015 investigation in that the depth to rockhead increases from north to south. The head deposits are predominantly cohesive and have been proved by previous testing to be negligibly permeable. During drilling, the pressure of the drilling bit and the pressure of the flush and the rate of drilling is continuously monitored by the driller. A sudden decrease in the pressure of bit or flush or sudden increase in drill rate can be indicative of fissured or voided ground. The flushed returns were inspected by a geoenvironmental engineer to determine the type of rock being drilled and to identify changes in strata. Sandstone or sandstone interbedded with limestone bedrock was initially encountered below the head deposits to depths of 7.00m bgl in BH1 and 5.50m bgl in BH2. The sandstone was generally fine grained and contained a significant proportion of silt sized particles. The drilling rate in this strata varied depending on whether limestone or sandstone was being drilled, and was significantly slower in the limestone which was harder but no sudden decreases/increases in rate were noted. In addition there was no sudden decreases in pressure on the drilling bit or flush. Below the sandstone or interbedded sandstone and limestone, intact limestone rock was encountered. The limestone was significantly harder and this was evidenced by much slower progress in drilling and the requirement for a change in drilling bit from a tri cone rock roller to DTH hammer. In the majority of the limestone the rate of drilling was constant with no obvious decreases in pressure of bit or flush, however a complete loss of flush was encountered together with a ‘drop’ of the drilling tools in BH1 between 12.00 and 12.50m bgl. This was identified as voided strata and a constant head permeability test was attempted at 12.50m bgl.


Following the test a foam flush was introduced to the voided area so that the borehole could be progressed to the target depth of 20m bgl. Below the void the strata was again drilled at a constant rate with no obvious decreases in pressure of bit or flush indicating that the rock was again intact without any significant fissures or fractures.

5 Testing BH1 – Test 1 – Falling Head The borehole was initially progressed to 10m bgl and then water was introduced to the bottom of the casing at 1.50m bgl. The groundwater was then monitored for a period of 30mins over which period there was no significant fall in water level. BH1 – Test 2 – Constant Head The borehole was progressed and on encountering suspected voided strata between depths of 12.00 and 12.50m bgl a constant rate test was attempted. Water was discharge into the borehole at the approximate rate of 16 litres/second for 11 minutes (10,560 litres). However, it was not possible to introduce a head of water into the borehole as the water was draining at such a high rate. BH1 – Test 3 – Falling Head The borehole was progressed to the target depth of 20.00m bgl and then water introduced to a depth of 12.50m bgl which corresponded to the base of the voided strata. The groundwater level was then monitored over a period of 30mins over which period there was no significant fall in water level. BH2 – Test 1 – Falling Head The borehole was progressed to a depth of 7.00m bgl and then water introduced to the base of the casing at a depth of 3.00m bgl. The groundwater level was then monitored over a period of 30mins over which period there was no significant fall in water level. BH2 – Test 2 – Falling Head The borehole was progressed to the target depth of 20.00m bgl and then water introduced to a depth of 10m bgl. The groundwater level was then monitored over a period of 30mins over which period there was no significant fall in water level.

6 Conclusions

All the attempted falling head tests in solid strata failed to record a significant fall in water level over a range of response zones. It is considered that this is due to the scarcity of fissures and fractures within the limestone of the Hythe Beds which provide the primary pathway for water flow through the rock mass. This is further confirmed by the constant drilling rates and flush/bit pressures recorded when progressing the boreholes.


However, voided limestone was encountered in BH1 from 12.00m to 12.50m and it was demonstrated, through discharging high volumes of water, that significant infiltration drainage potential exists where fractures are present. It can therefore be confirmed, at least in the area of BH1 (north of site), that drainage via deep bored soakaways is viable. However, we would advise that when the proposed layouts have been confirmed, further soakage testing is undertaken across the site to confirm the most appropriate locations for deep bored soakaways. We trust that the above meets with your present requirements. Should you should have any further queries please do not hesitate to contact the undersigned.

Yours sincerely

Mike Williams Senior Geoenvironmental Engineer D: 01233 610530 M: 07825 032687 E: [email protected] Enc.: 772845-DWG-ENV-001 Exploratory Hole Location Plan Appendix A - Borehole Logs

Figure

772845-DWG-ENV-001 Exploratory Hole Location Plan

Project: Land of Heath Road, Coxheath

Borehole Location Plan

Job No. 772845

Figure No. 1

N

BH2

BH1

Appendix A

Borehole Logs

Project:

Project ID:

Location:

Client:

ProjectEngineer:

Land off Heath Road

772845

Heath Road, Coxheath, ME17 4EQ

Chris Atkinson

Method:

Start:

Finish:

Level (mOD):

Co-ordinates:

RO

18/06/2015

18/06/2015BH1

1:50

573721.16E -

151363.49N

Sheet 1 of 3

Logged by:

SP/OT

General Notes1. Shear Strengths determined by hand shear vane.2. See key sheet for explanation of symbols

Remarks

1) Prior to drilling borehole position scanned by CAT scanner and GPR to check for services. 2) Hand dug service inspectionpit to 1.20m bgl. 3) Borehole progressed using rotary open hole method and air flush to 12m bgl and using foam flush thereafter. 4) Heavily voided strata encountered from 12.00 to 12.45m bgl evidenced by total loss of air flush. 5) Heavily voided at 10.00m bgl (Falling Head), 12m (Constant Head) and 20m (Falling Head). 6) No groundwater strikes encountered. 7) On completion borehole backfilled with pea shingle from 20.00m bgl to 1.00m bgl and with bentonite from 1.00m bgl to GL.

WDUBSC

TCR (%)

SCR (%)

RQD (%)

Water StrikeWater StandingWater SampleSmall Disturbed SampleUndisturbed SampleBulk SampleStandard Penetration Test - Split Spoon MethodStandard Penetration Test - Solid Cone MethodRatio of core recovered (solid & non intact) to length of core runRatio of solid core recovered to length of core runRatio of solid core pieces longer than 100mm to length of core run

DRILLING

Depth

0.30

1.50

7.00

Casing(m)

1.50

Water

CORE RECOVERY

Depth(m)

TCR(%)

SCR(%)

RQD(%)

SAMPLE/TEST

SampleDepth &

Type(m)

Test Depth &

Type(m)

TestResult

Level(mAOD)

Thickness(m)

0.30

1.20

5.50

5.00

LEGEND DESCRIPTION OF STRATA

Grass over light orangish brown clayey fine to coarse SAND.TOPSOIL

Orangish brown sandy CLAY with occasional gravel and cobble sized sandstone fragments.HEAD

Yellowish brown SANDSTONE with interbedded limestone bands.HYTHE FORMATION

Strong blueish grey LIMESTONE (slow progress)HYTHE FORMATION

Continued on next sheet

Project:

Project ID:

Location:

Client:

ProjectEngineer:

Land off Heath Road

772845


Chris Atkinson

Method:

Start:

Finish:

Level (mOD):

Co-ordinates:

RO

18/06/2015

18/06/2015BH1

1:50

573721.16E -

151363.49N

Sheet 2 of 3

Logged by:

SP/OT


Remarks


WDUBSC

TCR (%)

SCR (%)

RQD (%)


DRILLING

Depth

12.00

12.50

Casing(m)

Water

CORE RECOVERY

Depth(m)

TCR(%)

SCR(%)

RQD(%)

SAMPLE/TEST

SampleDepth &

Type(m)

Test Depth &

Type(m)

TestResult

Level(mAOD)

Thickness(m)

0.50

7.50


Total loss of flushVOID

Blueish grey LIMESTONEHYTHE FORMATION


Project:

Project ID:

Location:

Client:

ProjectEngineer:

Land off Heath Road

772845


Chris Atkinson

Method:

Start:

Finish:

Level (mOD):

Co-ordinates:

RO

18/06/2015

18/06/2015BH1

1:50

573721.16E -

151363.49N

Sheet 3 of 3

Logged by:

SP/OT


Remarks


WDUBSC

TCR (%)

SCR (%)

RQD (%)


DRILLING

Depth

20.00

Casing(m)

Water

CORE RECOVERY

Depth(m)

TCR(%)

SCR(%)

RQD(%)

SAMPLE/TEST

SampleDepth &

Type(m)

Test Depth &

Type(m)

TestResult

Level(mAOD)

Thickness(m)


End of borehole at 20.00 m

Project:

Project ID:

Location:

Client:

ProjectEngineer:

Land off Heath Road

772845


Chris Atkinson

Method:

Start:

Finish:

Level (mOD):

Co-ordinates:

RO

19/06/2015

19/06/2015BH2

1:50

573799.08E -

151506.71N

Sheet 1 of 3

Logged by:

SP/OT


Remarks

1) Prior to drilling borehole position scanned by CAT scanner and GPR to check for services. 2) Hand dug service inspectionpit to 1.20m bgl. 3) Boreholes progressed using rotary open hole method and air flush to base of borehole. 4) Casing installed to 3.00m bgl (Top of Rockhead). 5) Permeability testing undertaken at 7.00m bgl (Falling Head) and 20.00m bgl (Falling Head). 6) No significant voided or fractured strata encountered. 7) No groundwater strike encountered. 8) On completion borehole backfilled with pea shingle from 20.00m bgl to 1.00m bgl and with bentonite from 1.00m bgl to GL.

WDUBSC

TCR (%)

SCR (%)

RQD (%)


DRILLING

Depth

0.30

2.80

5.50

Casing(m)

3.00

Water

CORE RECOVERY

Depth(m)

TCR(%)

SCR(%)

RQD(%)

SAMPLE/TEST

SampleDepth &

Type(m)

Test Depth &

Type(m)

TestResult

Level(mAOD)

Thickness(m)

0.30

2.50

2.70


Grass over light orangish brown clayey fine to coarse SAND.TOPSOIL

Orangish brown sandy slightly gravelly CLAY with rare cobbles from 2.2m. Sand is fine to coarse. Gravel is fine to medium angular sandstone. Cobbles are of limestone.HEAD

Initially highly weathered becoming less weathered with depth greenish brown clayey fine to coarse SANDSTONE.HYTHE FORMATION

Strong blueish grey LIMESTONE (slow progress).HYTHE FORMATION


Project:

Project ID:

Location:

Client:

ProjectEngineer:

Land off Heath Road

772845


Chris Atkinson

Method:

Start:

Finish:

Level (mOD):

Co-ordinates:

RO

19/06/2015

19/06/2015BH2

1:50

573799.08E -

151506.71N

Sheet 2 of 3

Logged by:

SP/OT


Remarks


WDUBSC

TCR (%)

SCR (%)

RQD (%)


DRILLING

DepthCasing

(m)Water

CORE RECOVERY

Depth(m)

TCR(%)

SCR(%)

RQD(%)

SAMPLE/TEST

SampleDepth &

Type(m)

Test Depth &

Type(m)

TestResult

Level(mAOD)

Thickness(m)

14.50



Project:

Project ID:

Location:

Client:

ProjectEngineer:

Land off Heath Road

772845


Chris Atkinson

Method:

Start:

Finish:

Level (mOD):

Co-ordinates:

RO

19/06/2015

19/06/2015BH2

1:50

573799.08E -

151506.71N

Sheet 3 of 3

Logged by:

SP/OT


Remarks


WDUBSC

TCR (%)

SCR (%)

RQD (%)


DRILLING

Depth

20.00

Casing(m)

Water

CORE RECOVERY

Depth(m)

TCR(%)

SCR(%)

RQD(%)

SAMPLE/TEST

SampleDepth &

Type(m)

Test Depth &

Type(m)

TestResult

Level(mAOD)

Thickness(m)


End of borehole at 20.00 m

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