BRETT TARMAC FAIRLOP QUARRY BRIEFING NOTE 2: HYDROGEOLOGY … · BRETT TARMAC FAIRLOP QUARRY BRIEFING NOTE 2: HYDROGEOLOGY FEBRUARY 2016 further tried and tested technology will be

BRETT TARMAC FAIRLOP QUARRY BRIEFING NOTE 2: HYDROGEOLOGY FEBRUARY 2016

PROPOSED EXTENSIONS OF EXISTING SAND AND GRAVEL WORKINGS ON TO LAND WEST OF ALDBOROUGH ROAD NORTH (PHASE E) AND WEST OF HAINAULT ROAD (PHASE F)

1 Introduction SLR provides specialist consultancy services to mining and minerals, waste management, planning and development businesses. Our hydrology and hydrogeologists have completed many schemes similar to those proposed for Fairlop Quarry.

2 Current setting (figure 1)

the proposed development at Fairlop Quarry would include sand and

gravel extraction across two Phases (E and F), followed by restoration back to agricultural land, and nature conservation habitats.

the sand and gravel (up to 7.3m thick) is just below the topsoil and

subsoil horizons underlain by London Clay.

some of the mineral contains groundwater – from rain falling on Fairlop Plain and surrounding areas.

groundwater levels and quality are routinely monitored via a network of monitoring boreholes that have been installed around the edge of Fairlop Quarry, including the proposed Phases E and F.

Groundwater flow (figure 2)

groundwater flow directions are shown in Figure 2. Across the western and central parts of Phase E, the flow direction is westerly towards the Cran Brook. Beneath the eastern part of Phase E, it is to the east, towards Seven Kings Water. Groundwater flow across Phase F is south-westerly toward Seven Kings Water.

the monitoring results have been analysed to identify both the

groundwater and surface water conditions – and to assess any potential interaction between the proposed mineral extraction and restoration activities, and the surrounding area.


specific measures are identified within the proposed scheme to make sure that: - groundwater levels are not lowered significantly around Phase E

during the dewatering of the sand and gravel before or while it is extracted

- flood risk is not increased around Phases E and F, either during quarrying activities or following restoration

- any potentially contaminated groundwater from the historic landfills to the north of Phase E is not drawn in to the water management systems at Fairlop Quarry

- the quality of water removed from Phase E during quarrying and restoration activities can be adequately treated for removal of suspended solids before being released back into the surrounding environment.

the proposed scheme has been developed to minimise any significant

impacts on the surrounding water environment.

3 Phase E Mineral extraction (Figure 3) before sand and gravel is extracted from Phase E a perimeter seal will

be installed around the western, northern and eastern boundaries of the Phase E extraction area, so that the groundwater within the sand and gravel can be lowered by pumping to allow it to be ‘worked dry’.

pumping will only be local to each sub phase and not across the whole of Phase E at any one time.

the perimeter seal will prevent any poor quality groundwater within the

historic landfill north of Phase E from draining into the quarry during extraction.

the perimeter seal will be a wall of bentonite mixed with cement, which

will be installed through the full thickness of sand and gravel down to the London Clay, without the need for any dewatering.

trenches will also be installed to recharge groundwater back into the

sand and gravel along the southern perimeter of Phase E. This will prevent the drawdown of groundwater levels to the south of the site, particularly below St Peter’s Church.


further tried and tested technology will be used to construct a clay wall

around the southern edge of Phase E. This will extend from ground level, through the sand and gravel and down to the London Clay.

this clay wall will also stop groundwater drawdown off site to the south

of the Phase E extraction area during ‘dry working’ of the sand and gravel.

Restoration (figure 4)

the quarry void will be infilled and restored back to existing ground

levels, using on site materials and strictly controlled imported inert materials. These will be covered by subsoil and topsoil.

the restoration operations will be carried out under the strict controls

and requirements of an Environmental Permit, which will be issued, regulated and enforced by the Environment Agency. Strict Waste Acceptance Criteria (WAC) will make sure that only inert materials are used.

rainfall running off the restored surface will be captured by an

agricultural drainage system around the edges of the site. This system will divert surface water run off to low lying areas dug down into the remaining sand and gravel around the perimeter of Phase E.

these low-lying areas (infiltration basins), will allow rainfall runoff to

drain back into the sand and gravel. This will reduce the risk of any flooding and maintain groundwater and surface water levels and flows around the quarry.

following completion of site restoration, the perimeter seal and clay

walls installed around Phase E will not be removed. They will stay in place and form a permanent geological barrier around the inert materials placed in the void for restoration.

4 Phase F

Mineral extraction there will be no groundwater dewatering during sand and gravel

extraction from Phase F, so the extraction void will remain flooded throughout.


as extraction of sand and gravel from Phase F proceeds – and

extraction activities are completed – the flooded void will be used as part of the quarry water treatment/recycling system. This will allow silt to settle out from the water used to wash and process the excavated sand and gravel.

Restoration the part of the flooded quarry below the groundwater will be completely

filled up with silt from the mineral washing process.

The remaining void will be restored back to original ground levels, by backfilling with excavated clay materials sourced from a separate extraction phase within the Phase F area before being covered by subsoil and topsoil.

without appropriate measures, it is likely that the silt deposited within

the Phase F excavation could hinder the groundwater moving across Phase F, within the surrounding sand and gravel.

this effect will be prevented by installing a new drainage channel along

the north-eastern perimeter of the Phase F extraction. The base of this drainage channel will be connected to the sand and gravel aquifer. Groundwater will be able to move up into the drainage channel from below. It can then flow around Phase F before draining into the Hog Hill Ditch – which will continue to feed the Seven Kings Water.

Groundwater and surface water monitoring programme for Phases E and F A groundwater monitoring programme will be carried out before, during and after the quarrying and restoration of Phases E and F. The existing network of monitoring points will be expanded, so the monitoring programme will: confirm the proposed mineral extraction and associated activities at

Fairlop Quarry are not having – and will not have any – significant impact on water quality and water levels in the surrounding groundwater and streams, including the Cran Brook, Hog Hill Ditch and Seven Kings Water.


make sure the requirements of the Environmental Permit for restoration with inert materials of Phases E and F are met.

5 Enhanced restoration

The application includes proposals to enhance the restoration schemes in Phase A (east), Phase D, and the Plant Site to include new nature conservation habitats. In all cases the proposed enhanced schemes will create new water areas that will have the ability to store any excess run off from the surrounding landforms.

PHASE E

Aldborough HatchLandfill (Historic)

Topsoil / Subsoil

London Clay

HistoricWaste

St. Peter'sChurch

Figure 1 - Current Setting - Before Extraction Starts

Figure 3 - Future Setting - During Extraction

Groundwaterwithin Sand &Gravel Aquifer

North South

Sand & Gravel

(upto 7.3m thick)

Not to Scale(Vertical dimensions are exaggerated)

NOTESLEGEND

Scale Date

TREENWOOD HOUSEROWDEN LANE

BRADFORD-ON-AVONWILTS. BA15 2AU

T: 01225 309400F: 01225 309401

LANGFORD LODGE109 PEMBROKE ROADCLIFTON, BRISTOLBS8 3EUT: 01179 064280F: 01173 179535

FULMAR HOUSEBEIGNON CLOSEOCEAN WAYCARDIFF. CF24 5PBT: 0292 049 1010F: 029 2048 7903

4 WOODSIDE PLACECHARING CROSSGLASGOWG3 7QFT: 0141 353 5037F: 0141 353 5038

4/5 LOCHSIDE VIEWEDINBURGH PARKEDINBURGHEH12 9DHT: +44 (0)131 335 6830

8 STOW COURTSTOW-CUM-QUYCAMBRIDGECAMBRIDGESHIRE. CB25 9AST: 01223 813805F: 01223 813783

65 WOODBRIDGE ROADGUILDFORDSURREYGU1 4RDT:+44 (0)1483 889800

SUITE 1,JASON HOUSEKERRY HILLHORSFORTHLEEDS. LS18 4JRT: 0113 2580650F: 0113 2818832

19 HOLLINGWORTH COURTTURKEY MILLMAIDSTONEKENT. ME14 5PPT: 01622 609242F: 01622 695872

SAILORS BETHELHORATIO STREETNEWCASTLE UPON TYNETYNE AND WEAR. NE1 2PET: 0191 261 1966F: 0191 230 2346

ASPECT HOUSEASPECT BUSINESS PARKBENNERLEY ROADNOTTINGHAM. NG6 8WRT: 01159 647280F: 01159 751576

7 WORNAL PARKMENMARSH ROADWORMINGHALL, AYLESBURYBUCKS. HP18 9PHT: 01844 337380F: 01844 337381

2ND FLOORHERMES HOUSEHOLSWORTH PARKOXON BUSINESS PARKSHREWSBURY, SY3 5HJT: 01743 239250

8TH FLOOR, QUAY WESTMEDIACITYUKTRAFFORD WHARF ROADMANCHESTERM17 1HH, UKT:+44 (0)161 872 7564

LEGEND

69 POLSLOE ROADEXETERDEVONEX1 2NFT: +44 (0)1392 490152F: +44(0)1392 495572

WATERHOUSE BUSINESS CENTREUNIT 77, 2 CROMAR WAYCHELMSFORDESSEX CM1 2QE

T: 01245 392170F: 01245 392171

SLR CONSULTING IRELAND7 DUNDRUM BUSINESS PARKWINDY ARBOURDUBLIN 14

T: +353-1-2964667F: +353-1-2964676

8 PARKER COURTSTAFFORDSHIRE TECHNOLOGYPARK, BEACONSIDE,STAFFORD ST18 OWP

T: 01785 241755F: 01785 241780

SUITE 1 POTTERS QUAY5 RAVENHILL ROADBELFASTBT6 8DN

NORTHERN IRELANDT: +44 (0)28 9073 2493

402.

0092

9.00

005.

18.F

IGU

RE

1,3

,4,5

&6.

0 M

ulti-

layo

uts.

dwg UNIT 2, NEWTON BUSINESS CENTRETHORNCLIFFE PARK ESTATENEWTON CHAMBERS ROADCHAPELTOWN

SHEFFIELD, S35 2PWT:+44 (0)114 2455153

SUITE 5, BRINDLEY COURTGRESLEY ROADSHIRE BUSINESS PARKWORCESTER WR4 9FD

T: +44 (0)1905 751310F: +44 (0)1905 751311

2 LINCOLN STREETLANE COVENEW SOUTH WALES 2066AUSTRALIA

T: 61 2 9427 8100F: 61 2 9427 8200

83 VICTORIA STREETLONDONSW1H 0HW

T: 44 (0)203 691 58102

N

Contains OS data © Crown copyright [and database rights] (2015) 0100031673.Contains public sector information licensed under Open government Licence v3.0© Crown copyright [and database rights] 0100031673 Expires

214 UNION STREETABERDEENAB10 1TLT: +44 (0)1224 517405

NO. 68 STIRLING BUSINESS CENTREWELLGREENSTIRLINGFK8 2DZT: +44 (0)1786 239900

BUROCLUB157/155 COURS BERRIAT38028 GRENOBLE CEDEX 1FRANCET: + 33 4 76 70 93 41

www.slrconsulting.com

© This drawing and its content are the copyright of SLR Consulting Ltd and may not be reproduced or amended except by prior written permission. SLR Consulting Ltd accepts no liability for any amendments made by other persons.© This drawing and its content are the copyright of SLR Environmental Consulting (Ireland) Ltd and may not be reproduced or amended except by prior written permission. SLR Environmental Consulting (Ireland) Ltd accepts no liability for any amendments made by other persons.© This drawing and its content are the copyright of SLR Consulting France SAS and may not be reproduced or amended except by prior written permission. SLR Consulting France SAS accepts no liability for any amendments made by other persons.

FIGURE 1

NTS @ A3 JANUARY 2016

CURRENT SETTING - BEFORE

EXTRACTION STARTS

DRAWING_TITLE_3

HYDROGEOLOGICAL & HYDROLOGICALASSESSMENT

PROJECT_TITLE_3

FAIRLOP QUARRYSITE_NAME_2

[14.10.2016]2016

SPRINGS

CRAN BROOK

CULVERT ENTRANCE

CULVERTED SECTION

TO VALENTINES PARK

ALDBOROUGH HATCHFARM POND

ST. PETER'S CHURCH

LAGOON (APPROX.LOCATION)

SEVEN KINGS

WATER

FAIRLOP AIRFIELD

FAIRLOP QUARRY (AREA C)

FAIRLOP QUARRY

FAIRLOP COUNTY

PARK

23

24

2

5

2

6

26

25

24 LAGOON (APPROX.

LOCATION)

2

3

23

24

25

26

HOG HILL DITCH

26

2

4

23

25

24

25

26

2

6

25

24

2

3

23

ALDBOROUGH HATCH LANDFILL

APPLICATION SITEBOUNDARY

LAKE / POND / LAGOON

DRAINAGE DITCH / SURFACEWATER (ARROW INDICATESFLOW DIRECTION)

CULVERTED SECTION OFCRAN BROOK

HISTORIC LANDFILL

INFERRED GROUNDWATERCONTOURS (mAOD)

INFERRED GROUNDWATERFLOW DIRECTION

NOTES

LEGEND

Scale Date



T: 01225 309400F: 01225 309401





8 STOW COURTSTOW-CUM-QUYCAMBRIDGECAMBRIDGESHIRE. CB25 9AS

T: 01223 813805F: 01223 813783









LEGEND


WATERHOUSE BUSINESS CENTREUNIT 77, 2 CROMAR WAYCHELMSFORDESSEX CM1 2QET: 01245 392170F: 01245 392171SLR CONSULTING IRELAND7 DUNDRUM BUSINESS PARKWINDY ARBOURDUBLIN 14T: +353-1-2964667F: +353-1-2964676 8 PARKER COURTSTAFFORDSHIRE TECHNOLOGYPARK, BEACONSIDE,STAFFORD ST18 OWPT: 01785 241755F: 01785 241780SUITE 1 POTTERS QUAY5 RAVENHILL ROADBELFASTBT6 8DNNORTHERN IRELANDT: +44 (0)28 9073 2493

402.

0092

9.00

005.

18.F

IGU

RE

2.0

Gro

undw

ater

Lev

els.

dwg

UNIT 2, NEWTON BUSINESS CENTRETHORNCLIFFE PARK ESTATENEWTON CHAMBERS ROADCHAPELTOWNSHEFFIELD, S35 2PWT:+44 (0)114 2455153SUITE 5, BRINDLEY COURTGRESLEY ROADSHIRE BUSINESS PARKWORCESTER WR4 9FDT: +44 (0)1905 751310F: +44 (0)1905 7513112 LINCOLN STREETLANE COVENEW SOUTH WALES 2066AUSTRALIAT: 61 2 9427 8100F: 61 2 9427 820083 VICTORIA STREETLONDONSW1H 0HWT: 44 (0)203 691 58102

N

Contains OS data © Crown copyright [and database rights] (2015) 0100031673.Contains public sector information licensed under Open government Licence v3.0

© Crown copyright [and database rights] 0100031673 Expires






FIGURE 2

1:12,500 @ A3 JANUARY 2016

GROUNDWATER LEVELS

DRAWING_TITLE_2

DRAWING_TITLE_3


PROJECT_TITLE_3


[14.10.2016]2016

PHASE E

PHASE F

http://www.slrconsulting.com

PHASE E

Figure 3 - Future Setting - During Extraction

Sump

Recharge Trench

Bentonite SlurryPerimeter Seal

Topsoil / Subsoil

Sand & Gravel

(upto 7.3m thick)

London Clay

St. Peter'sChurch

HistoricWaste

Groundwater MonitoringBorehole (Quality and

Levels)


100m

NOTESLEGEND

Scale Date



T: 01225 309400F: 01225 309401














LEGEND



T: 01245 392170F: 01245 392171


T: +353-1-2964667F: +353-1-2964676


T: 01785 241755F: 01785 241780



402.

0092

9.00

005.

18.F

IGU

RE

1,3

,4,5

&6.

0 M

ulti-

layo

uts.


SHEFFIELD, S35 2PWT:+44 (0)114 2455153


T: +44 (0)1905 751310F: +44 (0)1905 751311


T: 61 2 9427 8100F: 61 2 9427 8200


T: 44 (0)203 691 58102

N







FIGURE 3


FUTURE SETTING - DURING

EXTRACTION

DRAWING_TITLE_3


PROJECT_TITLE_3


[14.10.2016]2016


PHASE E

Figure 4 - Future Setting - Following Restoration

Engineered ClayBarrier

Inert Waste

Natural Infiltration toSand & Gravel

Topsoil / Subsoil

London Clay

Precipitation

Runoff

Surface Water Attenuation /Recharge Area(s)

St. Peter'sChurch

HistoricWaste

Bentonite SlurryPerimeter Seal


100m

Sand & Gravel

(upto 7.3m thick)

NOTESLEGEND

Scale Date



T: 01225 309400F: 01225 309401














LEGEND



T: 01245 392170F: 01245 392171


T: +353-1-2964667F: +353-1-2964676


T: 01785 241755F: 01785 241780



402.

0092

9.00

005.

18.F

IGU

RE

1,3

,4,5

&6.

0 M

ulti-

layo

uts.


SHEFFIELD, S35 2PWT:+44 (0)114 2455153


T: +44 (0)1905 751310F: +44 (0)1905 751311


T: 61 2 9427 8100F: 61 2 9427 8200


T: 44 (0)203 691 58102

N







FIGURE 4


FUTURE SETTING - FOLLOWING

RESTORATION

DRAWING_TITLE_3


PROJECT_TITLE_3


[14.10.2016]2016


Documents

BRETT TARMAC FAIRLOP QUARRY BRIEFING NOTE 2: HYDROGEOLOGY … · BRETT TARMAC FAIRLOP QUARRY BRIEFING NOTE 2: HYDROGEOLOGY FEBRUARY 2016 further tried and tested technology will be