13 hydrogeological and hydrological assessment

Croxden Quarry: Part B – Environmental Statement

WA Ref: ST11571-RPT-001

13 – Hydrogeological and Hydrological Assessment 13-3

13 HYDROGEOLOGICAL AND HYDROLOGICAL ASSESSMENT

13.1 Introduction

13.1.1 BCL Consultant Hydrogeologists Limited (BCL) have been commissioned by the Applicant to undertake a Hydrological and Hydrogeological Impact Assessment (HIA) to accompany the Planning Application seeking a time extension for working at Croxden Quarry, Nr Cheadle, Staffordshire (the Site).

13.1.2 The application is to be accompanied by an Environmental Impact Assessment (EIA) of which this chapter forms part of. The mode of working and restoration described by the application will be identical to that associated with the current permission (which, itself, was granted following consideration of a full EIA in 1991). It therefore follows that the current EIA will focus upon potential impacts associated with the proposed time extension.

13.1.3 This chapter documents the findings of the HIA, which builds upon the aforementioned 1991 Assessment, and incorporates the various additional hydrometric data and results of assessment collected over the intervening years, to develop a refined conceptual model for the locality. This refined model has been used in the assessment of the proposed time extension to working.

13.1.4 Potential impacts identified during the course of investigations have been addressed by proposals for mitigation to be incorporated into the working scheme for the Site.

13.1.5 Where appropriate, outline monitoring protocols have been advanced to allow for validation of the extent of impact.

13.2 Methodology and Data Sources

13.2.1 To achieve the aims outlined above, a programme of desk and field study has been completed. The sources of information used within these works are outlined below:

i). Ordnance Survey

� 1:25,000 Explorer series. Sheet 259 Derby.

� 1:1,250 digital tile data.

ii). Environment Agency

� Long-term monthly average rainfall data.

� Radial search of abstraction licensing database.

� Historical flooding data.

� Groundwater level data.

� Surface watercourses stage elevation and flow data.

iii). Natural England (NE)

� Spatial mapping & citation information for designated sites of ecological interest.

iv). Institute of Hydrology (IoH)

� Well records register

v). British Geological Survey (BGS)

� 1:50,000 Published geological map. Sheet No 124 Ashbourne, Solid with Drift Edition.

� Geology of the country around Ashbourne and Cheadle. BGS Memoir for Geological Sheet 124. 1998.

� Report of the Minerals Assessment Unit No. 57. SK04 Cheadle Staffordshire.

vi). Field investigations.

� Water features survey including investigation of Private Water supplies.

� Investigation of the stream channel – Croxden Brook.

� Flow gauge exercise – accretion profile of Croxden and Winnothdale Brooks.

vii). Miscellaneous sources

� “Calculation of Water Balance for Croxden and Winnothdale Brooks.” Environmental Simulations International Limited. October 2001.




� “An investigation of the hydrogeological regime in the vicinity of Croxden Quarry, Cheadle Staffordshire.” Tarmac Quarry Products Limited, January 1998.

� “A hydrogeological investigation of the region around Croxden Quarry Nr. Cheadle, Staffordshire with a view to assessing potential impacts an extension of quarrying activity may have.” MSc Thesis. E Wrathmell, University of Birmingham. September 1996.

� “Croxden Quarry. An assessment of the hydrological and hydrogeological impacts of further quarry development.” Scott Wilson Kirkpatrick, September 1991.

Structure of Report

13.2.2 Descriptive data concerning the baseline conditions for the area within and surrounding the Site, collected during both the field and desk studies, are presented at section 13.2. The baseline characterisation includes details upon topography, geology, hydrology and hydrogeology.

13.2.3 An assessment of the potential effects and consequences of the proposed time extension, and description of mitigation measures to ameliorate any impacts, are made at section 13.3.

13.2.4 A report summary is provided as section 13.4 and report conclusions given in section 13.5.

13.2.5 All diagrams and figures referred to within this report are included at Appendix 13.1.

13.3 The Baseline Study

Site Location and Land Use

13.3.1 Croxden Quarry is located approximately 1.5 kilometres (km) south-east of Cheadle, within the drainage basin of the River Dove (Figure 1, Appendix 13.1). The national grid reference (NGR) for the centre of the Site is SK 032 417.

13.3.2 The Site occupies an area of approximately 201ha. The quarry comprises a mix of active mineral extraction and processing areas, alongside previously worked areas restored to provide a range of nature conservation habitats. The Site is surrounded by principally agricultural land given over to pasture, with some areas of woodland.

Designated Sites

13.3.3 There are no Sites of Special Scientific Interest (SSSI) within a survey radius 2 km from the centre of the site. The closest SSSI (known as Dimmings Dale and the Ranger) is located some 2.3km north-east of the Site, on the southern flank of the River Churnet Valley.

13.3.4 The citation for the SSSI describes Dimmings Dale as a predominantly wooded valley and associated watercourse, which together support a rich invertebrate fauna. The watercourse forms a tributary to the River Churnet. The Ranger comprises a small area of wet and dry lowland heath again supporting a range of invertebrates and bog mosses.

13.3.5 There is one statutory site located adjacent to the search area described above. This is the Cecilly Brook Local Nature Reserve (LNR) located to the east of Cheadle town centre. Cecilly Brook is an upper tributary to the River Tean. The LNR site is important for its population of water voles.

The Permitted Development

13.3.6 The existing permission (SM.91/1355) allows extraction of mineral to a level 3 metres (m) above the “natural winter watertable” (Condition 57), within the site boundary shown at Figure 2. The areas remaining for extraction are located in three discrete phase areas also shown at Figure 2.

13.3.7 The extraction of sand and gravel will follow the pattern established within the current quarry workings. Sand and gravel will be extracted using a D11 dozer, hydraulic excavator with mineral being transported to the existing processing plant, utilising a combination of field conveyors and quarry vehicles.

13.3.8 Mineral washing water for use within the plant is currently abstracted from the clean water lagoon of the existing settlement system (located to the west of the processing plant). Water is also abstracted under licence from a borehole installed into the underlying economic mineral to the east of the




quarry plant processing area (NGR SK 0370 4130) for supply to the vehicle wheel wash and for top-up supply to the mineral washing system. Mineral washing water is re-circulated from the plant to the settlement lagoon system.

13.3.9 The current silt settlement area is located immediately to the north of the quarry access road. In accordance with the existing planning permission for the Site the lagoon area will be relocated to the south-eastern section of the Site once the existing lagoon is filled.

13.3.10 Following the completion of mineral extraction, the Site will be restored to a combination of low-level nature conservation areas comprising shallow open waterbodies, reed beds, woodland and grassland habitats. The restoration plan for the Site is reproduced at Figure 3.

Previous Investigations

13.3.11 Hydrogeological investigations have previously been conducted in respect of both the current planning permission and other water related matters in the locality (section 13.2.1 (vi and vii) below). Studies have also been undertaken during the completion of an MSc thesis based on the area and as part of investigations commissioned by the Environment Agency (EA) to examine flows within the wider surface water catchment.

13.3.12 A scheme of hydrometric monitoring has also been operated at the Site since April 1996. Alongside the regular monitoring data, the aforementioned investigations have generated a significant amount of site specific baseline data (including groundwater elevation, surface water elevation, aquifer property, abstraction, rainfall and stream flow data).

Topography

13.3.13 The Site is located upon an area of elevated ground comprising the eastern flank of the River Tean Valley at Cheadle, Staffordshire (Figure 1).

13.3.14 The topography to the north, north-east and east of the Site generally comprises an elevated area bounded by the River Churnet Valley. This is located some 3km from the Site at the closest approach. The Churnet Valley comprises a relatively steeply sided valley typical of the glaciated landscape in the locality, where increased flows from meltwater has resulted in the significant deepening of pre-existing valleys.

13.3.15 The Churnet Valley is generally orientated northwest to south-east with a basal elevation of some 98 metres (m) Above Ordnance Datum (AOD) and valley flanks between 150mAOD and 200mAOD. The valley opens to the River Dove Valley at Rochester, some 8km east – south-east of the Site.

13.3.16 The River Tean Valley defines the western, southwestern and southern boundaries of the study area. Between Cheadle and Upper Tean the valley is generally orientated north to south. At Upper Tean the orientation of the valley rotates to the south-east, before opening to the River Dove Valley at Uttoxeter (some 8km south-east of the Site). The basal elevation of the valley occurs at 125mAOD at Upper Tean, decreasing to 80mAOD at Uttoxeter and the River Dove Valley.

13.3.17 Within this defined study area, ground elevations generally attain maximum levels in the northwestern section and decrease in a south-easterly direction towards the River Dove Valley. The Site is situated within the northwestern section of this study area.

13.3.18 Local to the Site, the eastern flank of the River Tean Valley is defined by a relatively steep, scarp slope rising from an elevation of some 157mAOD at Cheadle, to a maximum of some 247mAOD at Counslow, on the Cheadle – Alton road (immediately north of the Site).

13.3.19 Croxden Quarry extends across this scarp slope and to the south-east. In accordance with the current planning permission for the Site, within the Site boundary the scarp slope has been quarried and the Old Counslow Road (which ran along the top of the scarp) has been realigned to run on a raised embankment now forming the western boundary of the Site.

13.3.20 The local area to the north, east and south of the Site is intersected by a series of small valleys. The closest of these features to the Site are associated with the Croxden and the Winnothdale Brooks.

13.3.21 The valley associated with the Croxden Brook is located to the east of the Site. This feature is generally orientated north-northwest to south-south-east, with basal elevations of between 200mAOD at the head of the valley near Threapwood (approximately 0.7km north-east of the Site),




160mAOD at Lightoaks Farm (approximately 0.5km east of the Site) and 140mAOD at Great Gate some 1.4km south-east of the Site. The Croxden Brook Valley comprises a relatively steeply sided valley defined with flanks at elevations of between 200mAOD and 230mAOD.

13.3.22 The valley associated with the Winnothdale Brook is located to the south of the Site. The head of the valley forms in the vicinity of Freehay some 500m west of the Site entrance. Between Freehay and Winnothdale (some 1.5km to the south-east of the valley head) the valley forms a broad shallow feature decreasing in elevation from 220mAOD to 180mAOD.

13.3.23 East of Winnothdale the valley becomes more steeply sided and changes orientation to head eastwards and join with the Croxden Brook valley some 2km downstream at Great Gate. The basal elevation of the valley between these two locations decreases from 170mAOD at Spring Farm to 140mAOD at Great Gate.

13.3.24 Surface elevations within the excavated void at Croxden Quarry generally vary between 180mAOD in the south-east to 220mAOD to the northwest. The base of working occurs some 35m and 50m below the original land surface.

13.3.25 Within the eastern and south-eastern sections of the Site a number of areas of former mineral extraction have been restored to woodland plantation. Ground elevations within these areas occur between 201mAOD and 210mAOD, the lower areas now residing some 25m below the original land surface.

Geology

Background

13.3.26 The stratigraphic sequence prevailing in the vicinity of the Site is shown on Figures 4A and 4B. The solid geology within the locality comprise Permo-Triassic sedimentary deposits unconformably overlying strata of Carboniferous age. It is units within the Permo-Triassic deposits that form the economic mineral at the Site.

13.3.27 The geology within the locality has been determined by reference to the following data sources:

i). Geological logs of mineral evaluation and boreholes drilled within, and immediately local to, the Site.

ii). Information contained within BGS Mineral Assessment Unit Reports, BGS maps, BGS Memoirs and other publications.

iii). Examination of exposures rendered by the quarry workings.

Regional Geology

13.3.28 The regional geology within the vicinity of the Site is shown on Figure 4A. A summary of the stratigraphic sequence of the area is presented at Table 13.1.

13.3.29 The oldest strata in the locality belong to the Carboniferous Coal Measures. These occur in outcrop in the northwest of the district and are present at depth beneath the Permo-Triassic deposits of the study area. Within the outcrop area, the Coal Measures are preserved in the Cheadle Syncline, displaying shallow dips of generally less than 10o.

13.3.30 In the south-east of the district the Carboniferous strata are unconformably overlain by Triassic deposits of the Sherwood Sandstone Group. The regional dip of these strata is generally between 0o and 5o to the south, reflective of the area’s position to the north of the Needwood Basin.




Table 13.1: Regional Geology

Age Lithology Description

Qua

rter

nary

Alluvium

Present within a number of valleys within the district as narrow and intermittent deposits encompassing the associated watercourses. Primarily present within the valleys associated with the Rivers Dove, Churnet and Tean, but also present in a limited extent adjacent to the Croxden Brook downstream of Great Gate. Typically consists of an upper layer of silt and an underlying poorly sorted gravel.

River Terrace Sand and Gravel

Mainly associated with the principle watercourses in the district, but with more limited deposits located around some of the smaller tributaries e.g Croxden Brook at Croxden. Formed from material derived from earlier deposits and comprise generally sandy gravel with higher silt content on the lower terraces.

Head Poorly sorted and poorly stratified mixture of drift and bedrock material present within two valleys in the south-east of the district at Forsbrook and Checkley. Tends to be linked to Lower Terrace deposits.

Glacial Sand and Gravel Present as a small number of discrete deposits principally on the higher ground in the south of the district. Comprise gravel in a sand matrix. Classified as boulder clay as matrix becomes more silt/clay.

Boulder Clay (Till) Widely distributed throughout the district as discrete deposits. Comprise a poorly sorted unstratified mixture of rock fragments up to boulder size in a matrix of clay/silt.

Per

mo

-Tria

ssic

Mer

cia

Mud

ston

e G

roup

Generally red-brown and grey-green calcareous or dolomitic mudstones and siltstones with subordinate sandstones. Widely distributed in the southern half of the district. Generally conformably overlies the Sherwood Sandstone Group but locally overlaps onto Carboniferous Strata. Subdivision above the Denstone Formation has not proved possible. The undivided upper part of the Mercia Mudstone has previously been named the Keuper Marl.

Denstone Formation

Defines the base of the Mercia Mudstone Group. Predominantly red-brown siltstones interlayered with thin subordinate fine grained sandstones and mudstones. Siltstones and sandstone layers are locally well cemented with calcite. Occuring in outcrop to the south and east of the district with a relatively constant thickness of around 50m.

She

rwoo

d S

ands

tone

Gro

up

Generally comprise red-brown and yellow sandstones, pebbly sandstones and conglomerates with very occasional siltsone and mudstone bands. The conglomerates form a large part of the sequence locally. Within the area to the east of Cheadle the unit has been subdivided. Elsewhere subdivision has not been possible with the group being mapped as a single unit.

Hollington Formation

Red-brown and yellow sandstones generally occuring as fining upwards units. Individual units grade from pebbles at the base to marl or mudstone bands at the top. Sandstones are commonly well cemented with baryte or calcite. Extremely variable in thickness from a featheredge at the Weaver Hill 7.5km to the north-eastnorth-east of the Site, to 50m thickness in the vicinity of Hollington 3km to the south-east.

Haw

ksm

oor

For

mat

ion

Yellow mottled, very fine – coarse grained sandstone with intermittant and discrete occurences of quartzite/quartz pebbles. Generally poorly cemented. Thickness varies from a maximum of 156m at Great Gate to a featheredge at the Weaver Hills. Includes two discrete conglomeratic units separated as members (described below).

Lodgedale Member

Recognised only in the area between Winnothdale and Great Gate. Comprise a laterally mapable sequence of weakly cemented conglomerate and pebbly sandstones within the Hawksmoor Formation. Attaining a maximum thickness of some 32m.

Freehay Member

Laterally mapable conglomerate sequence of up to 56m thickness. Consists of conglomerate with subordinate sandstones and occasional mudstone beds. Sandstones tend to be cemented and form lenses within deposit. Member becomes less defined laterally as proportion of sandstone increases.

Huntley Formation

Basal conglomeratic sequence present locally, mainly in the vicinity of Cheadle. Generally coarse grained sandstone and poorly sorted conglomerate of pebble sized, principally locally derived, sub-rounded to angular clasts. Strongly cemented with calcite or dolomite. The thickness varies from between 4 and 15m in the vicinity of Cheadle.

Unconformity

Car

boni

fero

us

Coal Measures

Interbedded grey mudstones, siltstones and sandstones with coal seams. Present in outcrop to the northwest of the district and extending beneath the Permo-Triassic cover to the east. Strata were folded and faulted and deeply eroded prior to the deposition of the Triassic sandstones.




Local Geology

13.3.31 The Site is underlain by the Freehay Member of the Hawksmoor Formation. The conglomeratic deposits of the Freehay Member are currently extracted within the existing quarry.

13.3.32 The vertical distribution of geological units local to the Site is shown in cross-section at Figure 5. The cross-section has been drawn to show the relationship between the individual members within the Hawksmoor Formation and the underlying Carboniferous strata.

13.3.33 The Hawksmoor Formation unconformably overlies Carboniferous Coal Measures strata. The Carboniferous Coal Measures comprise a series of interbedded sandstones, siltstones, mudstones and coal seams. The Coal Measures are present in outcrop within the River Tean Valley at Cheadle. Beneath the study area the upper (unconformable) surface of the Coal Measures occurs as a generally south-easterly dipping surface. The general dip of beds within the Coal Measures varies across the area but is generally low and to the southwest.

13.3.34 To the northwest of the Site the ground elevations drop sharply into the River Tean Valley. This change in elevation marks a lateral geological boundary between the outcrop of the overlying Triassic deposits to the south-east, and the Carboniferous Coal Measures within the valley floor. The contact between the two units occurs at an elevation of some 210mAOD in the vicinity of the Cheadle – Alton road, decreasing to 200mAOD, at Rakeway and 180mAOD in the vicinity of Freehay Wood. To the south-east, the subsurface elevation of the contact beneath the Triassic cover occurs at some 20mAOD in the vicinity of Great Gate.

13.3.35 Local to the Site the Hawksmoor Formation outcrops within a roughly triangular area (herein referred to as the ‘Croxden Aquifer Block’). This area is defined by the lateral outcrop extent of the Triassic strata to the northwest as described above, and by a series of interconnected faults to the south and east.

13.3.36 The eastern limit of the local outcrop of the Hawksmoor Formations is defined by a normal fault known locally as the Sandy Lane Fault. This is located approximately 500m east of the closest remaining extraction area, trending north-northwest to south-south-east. The fault has a displacement of some 50m resulting in younger Hollington Formation strata east of the fault juxtaposed against the Hawksmoor Formation strata encompassing the Site.

13.3.37 The “Southern Fault” is orientated west-northwest to east-south-east at a distance of some 2.5km from the Site. This is a normal fault with strata downthrown to the south by a displacement of some 100m. This has resulted in a thickness of some 80m of Mercia Mudstone Group strata juxtaposed against younger strata of the Sherwood Sandstone Group. The trace of the Southern Fault and the Sandy Lane Fault meet in the vicinity of Hollington some 2.5km south-east of the Site.

13.3.38 Several other faults have been identified within the Croxden Aquifer Block as described above. The largest of these faults is oriented north-northwest to south-south-east and is located across the centre of the quarry. Strata to the east of this fault are downthrown by a maximum of some 40m in the northern section of the Site, but reducing to 15m in the south. This fault is intercepted in the centre of the Site by a second fault, oriented north-east to southwest. Strata to the north of this second fault are downthrown by some 30m in the east of the Site, reducing to some 15m in the west.

13.3.39 Elsewhere within the Croxden Aquifer Block, faulting is generally smaller scale (less than 10m) and orientated east-north-east to west-southwest. The most significant of these is located within the southern section of the Site and, although not mapped explicitly by the BGS, the likely presence of this fault can be traced to the southwest linking into a valley feature within the Winnothdale Valley.

13.3.40 The general dip of Triassic strata within the Croxden Aquifer Block is 4o to the south-east. The basal facies within the Sherwood Sandstone Group are locally represented by the Huntley Formation. This unit comprises a poorly sorted, matrix supported conglomerate with a well-cemented matrix of silt or sand. The Huntley Formation has been mapped to the northwest of the Site, but, owing to its limited thickness, is generally not identified outside this area. The Huntley Formation is visible in outcrop close to the northwestern boundary of the Site in the vicinity of Lambskin Dale.

13.3.41 Locally the Hawksmoor Formation overlies the Huntley Formation but more generally, directly, and unconformably, overlies Carboniferous Strata. The Hawksmoor Formation comprises a red-brown, very fine-coarse grained sandstone with Quartz/Quartzite pebbles common in places. The deposit is generally poorly cemented and friable. The thickness of the deposit varies from a featheredge on the northwestern boundary of the Site to some 156m at Great Gate.




13.3.42 The Hawksmoor Formation includes two conglomeratic members, namely the Freehay and Lodgedale Members. The Freehay Member is present in outcrop across the majority of the northwestern section of the fault block encompassing the Site. In the areas to the east and south-east of the Site the Freehay Member is overlain by undifferentiated strata of the Hawksmoor Formation, and subsequently by the Lodgedale Member. The upper surface of the Freehay Member has been recorded within the Great Gate Borehole No. 1 [NGR SK 052 399] at an elevation of 95mAOD, some 45 metres below ground level.

13.3.43 The Freehay Member comprises a conglomerate deposit interbedded with subordinate sandstone bands/lenses and infrequent, minor, mudstone beds. The sandstones tend to be well-cemented, forming resistant ribs of between 1m and 2.5m thickness. These are visible within the exposed quarry faces in the locality. The conglomerate units generally occur as alternating matrix and clast supported sets of up to 2m thickness.

13.3.44 The inferred elevation for the base of the Freehay Member is shown at Figure 6. The elevation of this surface occurs as a generally south-easterly dipping plane locally affected by the faulting described above. Beneath the Site the basal elevation varies between approximately 239mAOD at the northwestern boundary of the Site to some 159mAOD at the south-eastern boundary.

13.3.45 Grading analyses have been performed upon samples of the Freehay Deposit extracted at Croxden Quarry. The grading data have been used to calculate an indicative value of hydraulic conductivity of the deposit. This value is based upon the “D90” value for the material (i.e. the particle size at which 10% of the material is finer). The D90 values for the deposit are presented below at Table 13.2. For comparison, D90 values are also presented for a number of MAU boreholes located within same deposit in the vicinity of the Site.

Table 13.2: Grading analyses for Freehay Member

Location D90 (mm)

TCL Croxden Quarry - Maximum 0.200

TCL Croxden Quarry - Minimum 0.075

TCL Croxden Quarry - Average 0.120

MAU Cheadle Common (SK04SW15) 0.0500

MAU South of Lords Coppice (SK04SW16) 0.0625

MAU Counslow Plantation (SK04SW14) 0.0625

13.3.46 The Lodgedale Member is present in outcrop primarily in the areas comprising the southern flank of the Winnothdale Valley and the western flank of the Croxden Valley between Great Gate and Coneydale Farm (NGR SK 043 409). Within this area the unit attains a maximum thickness of some 15m. The Lodgedale Member comprises pebbly sandstones and weakly cemented conglomerates. The conglomerates tend to dominate the deposit locally but are generally subordinate to the sandstones in the deposit as a whole.

13.3.47 The top of the Sherwood Sandstone Group is marked by the Hollington Formation. This comprises a cyclic sequence of fining upwards units typically varying between sandstone with pebbles at the base, through fine sandstone, to mudstones/marl at the top. Local to the Site the presence of the Hollington Formation is limited to areas to the east of the Sandy Lane Fault and at depth in the area to the south of the southern fault.

13.3.48 East of the Sandy Lane Fault the formation forms the base of the Croxden Brook Valley and is present beneath strata of the Mercia Mudstone Group capping the eastern flank of the valley. Within the valley floor the thickness of the unit equates to some 20m. Beneath the Mercia Mudstone in the eastern flank of the valley, the unit attains a thickness of some 70m.

13.3.49 Within the Hollington Formation a number of the more prominent mudstone bands have been locally mapped. One such band is seen in the eastern flank of the Croxden Brook Valley. This laterally continuous and relatively thick unit occurs at a generally constant elevation (185mAOD) close to the top of the formation.

13.3.50 The Hollington Formation is overlain by strata of the Mercia Mudstone Group. The base of this group is delineated by the Denstone Formation. The formation consists of a series of siltstones with thin, and




subordinate, layers of sandstone and mudstone. The Denstone Formation is present in outcrop upon the higher ground to the east of the Croxden Brook Valley and to the south of the Southern Fault.

13.3.51 Glacial till is recorded at a number of discrete locations local to the Site. These comprise generally thin deposits of clayey composition. The closest area of till deposition to the Site comprises a small area at Cheadle Common (NGR SK 028 414). Deposits of larger areal extent are also present upon the higher ground in the area to the south-east of Great Gate and within the River Tean Valley in the vicinity of Rakeway House.

13.3.52 Deposits of recent alluvium are associated with the principle watercourses in the locality. Adjacent to the smaller watercourses alluvium deposition has occurred to a limited and intermittent extent. Alluvium deposition associated with the Croxden Brook occurs only between Lightoaks Farm (NGR SK 046 411) and the village of Croxden. Alluvial deposition associated with the Winnothdale Brook is limited to a reach of some 300m upstream of its confluence with the Croxden Brook.

Hydrology

Rainfall

13.3.53 Rainfall data has been obtained for the EA gauging station located at Uttoxeter Sewage Treatment Works (NGR SK 094 345), some 9km south-east of the Site and at an elevation of some 78mAOD. Historical long-term average, together with more recent rainfall distribution data for the Uttoxeter site, is presented at Table 13.3. These data are considered to offer a good representation of the conditions that have prevailed at the Site.




Table 13.3: Recent rainfall data – Uttoxeter Sewage Treatment Works. Gauge Ref. 104024. NGR SK 094 345 Month Year

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total

1998 95 17.8 101.7 99.8 11.5 118.5 31.4 63.7 77.3 135.9 35.4 69.8 857.8

1999 106.2 45.6 84.7 60.3 50.7 78.5 21.8 65.8 65 86.7 36.5 94 795.8

2000 27.6 85.2 28.8 110.0 67.4 45.8 44.5 44 126.6 138.5 172.6 100.2 991.2

2001 38.1 74.9 101.2 73.2 54.8 59.6 71.1 54.4 106.6 38.9 25.2 698.01

2002 50.5 94.8 35.7 48.3 58.2 57.1 91.5 35.5 52.2 117.3 120.6 119.5 881.2

2003 65.8 26.1 27.6 41.1 0 49.4 28.2 28.7 46.1 46.6 92.2 451.81

2004 87.1 33.9 34 84.7 36.7 59.9 36.7 193.1 59 96.8 39.2 38.4 799.5

2005 44.8 49.4 33.6 55 26.7 56 53.9 43.1 54.9 110.3 60.3 67.6 655.6

2006 25.5 37.6 67.5 54.2 90.8 12.3 20.4 113.5 91.8 116.2 66.1 86.5 782.4

2007 99.3 90.2 43.1 10.9 89.1 170.5 130.6 36.5 35.4 33.3 66.3 75.9 881.1

2008 115.9 21 56.6 67.4 34.3 35.7 84.3 66.8 107 80.4 50 57.4 776.8

2009 56 20.9 33.5 47.1 79.6 111.4 157.4 50.7 18.7 60.1 108.9 62.2 806.5

2010 52.9 49.8 20.8 20.1 23.2 32.4 74.9 274.11

Long

term

average

74 57 59 54 55 63 50 61 60 69 78 77 757

Notes

1. Rainfall totals omit some monthly data.




13.3.54 It is apparent from the collected data that the locality experienced a prolonged phase of rainfall elevated above the long-term average during the period 1998-2002.

Surface Watercourses

13.3.55 The locations of surface watercourses within the vicinity of the Site are shown on Figure 7.

13.3.56 The Site is located within the drainage basin of the River Dove. The pattern of drainage local to the Site may be subdivided into three discrete catchment areas. To the north, incident rainfall flows via a series of tributaries into the River Churnet. At its closest approach the River Churnet is situated some 3km north-east of the Site, flowing within a relatively steeply incised valley (section 13.3).

13.3.57 To the west of the current quarry, runoff from incident rainfall flows into the catchment for the River Tean. The River Tean (referred to by various local tributary names in the upper reaches) flows from north to south in the vicinity of Cheadle, turning to the south-east at Upper Tean, to join the River Dove at Uttoxeter. At its closest approach the River Tean is located some 2.5km to the west of the Site and 3.5km to the southwest.

13.3.58 Within the aforementioned larger catchment area, Croxden Quarry is located at the eastern limit of a smaller catchment comprising a series of watercourses draining a broadly rectangular catchment area between the villages of Alton to the north and Hollington to the south. Incident rainfall within this area flows, via a series of interconnected and variously named watercourses, to join the River Dove in the vicinity of Combridge, approximately 6km east-south-east of the Site.

13.3.59 Within this catchment area the principal watercourses local to the Site are the Croxden and Winnothdale Brooks. The Croxden Brook is located to the east of the Site and flows from north to south originating in the vicinity of Newton (some 500m from the Site boundary). The watercourse flows south-eastwards through the villages of Great Gate and Croxden.

13.3.60 The Winnothdale Brook is a tributary to the Croxden Brook and is located some 700m to the south of the Site at its closest approach. The watercourse flows from west to east between the source in the vicinity of Winnothdale (some 900m south of the Site), and the confluence with the Croxden Brook at Great Gate. The confluence occurs some 1.5km south-east of the Site, the raised ground encompassing the Site forming an interfluve between the two watercourses.

13.3.61 The Croxden Brook is cited within the Environment Agency’s National Environment Programme (now AMP5) due to problematic low flow conditions within the watercourse. In accordance with this programme it is understood that Severn Trent Water Plc (STW) have commenced provision of augmentation discharge to the brook from the Great Gates pumping station, located adjacent to the aforementioned confluence with the Winnothdale Brook.

13.3.62 Stage data for the Croxden Brook is recorded by the EA at a gauging station at Great Gate. This shows flows (downstream of the confluence with the Winnothdale Brook) to vary historically between zero and some 100 litres per second (l/s).

13.3.63 Spot flow measurements, also taken by the EA, indicate flows within the Winnothdale Brook to vary historically between zero and 29l/s.

13.3.64 Accretion profiles for both the Winnothdale and Croxden Brooks have been undertaken by BCL as part of the field investigations carried out in respect of previous assessments in the locality. The results are presented at Figure 8.

13.3.65 At the time of the accretion survey, flows within the Croxden Brook were insufficient to maintain water levels within the ponds at Lightoaks Farm (sections 13.2.68 – 13.2.79). Downstream of this location the watercourse was dry to the confluence with the Winnothdale Brook.

13.3.66 Within the Winnothdale Brook, the data indicate a single area where the watercourse is gaining significant flows from groundwater. This occurs between 0 and 500m from the head of the brook at Spring Farm (NGR SK 0333 4030). The ingress to the brook within this area accounts for some 80% of the total flow from the brook at Great Gate.

13.3.67 Downstream of the confluence of the Winnothdale and Croxden Brooks the measured flow at Great Gate displayed a combined flow higher than those observed within the two upstream watercourses. This is expected to be reflective of the augmentation discharge made from the adjacent Great Gate site.




Ponds and Springs

13.3.68 The occurrence of waterbodies in the vicinity of the Site is strongly influenced by underlying geological conditions. A total of seventeen waterbodies are located within a 1km radius of the Site (Figure 7). These are principally located within the Site boundary and to the east of the Site within the Croxden Brook Valley.

13.3.69 The closest waterbody outside the Site boundary is located to the north of Coneydale Farm (PD1), adjacent to the Site boundary. This feature appears man-made and is possibly related to the former quarrying activity within the restored area to the west. The 1:25,000 scale OS map shows two ponds at this location. However, the water features survey undertaken as part of this assessment indicates the western pond has been infilled. At the time of survey, no inflow or outflow was visible from the remaining waterbody.

13.3.70 To the south-east of the Site the Croxden Brook flows into a series man-made ponds formed behind historic brick/concrete dams (PD2 and PD3). These comprise two ponds excavated into the course of the Croxden Brook, located some 650m from the Site boundary at the closest approach. During the summer months, input from the Croxden Brook is insufficient to maintain waterlevels within the ponds such that the downstream pond becomes dry. At such times, the reach of the Croxden Brook between the ponds and the confluence with the Winnothdale Brook (a reach of some 625m) is also dry.

13.3.71 To the east of the Croxden Brook Valley, the OS map for the area indicates the presence of a series of waterbodies located on the higher ground comprising the valley’s eastern and northern flanks (PD4 – PD9). These are generally seasonal features (dry at the time of survey) and appear to occur in relation to perched drainage caused by the presence at, or close to, outcrop of the mudstone band described at section 13.3.30.

13.3.72 Of the waterbodies described above, pond PD8 was the only waterbody present at the time of survey. This pond is situated at an elevation of some 190mAOD. The level of water within the pond is maintained by a spring (see 13.3.72 below) emerging at the northern edge of the waterbody.

13.3.73 The presence of a spring (S1) appears to be related to the perching of groundwater upon the aforementioned mudstone band, and fed by a catchment comprising the upper slopes of the eastern flank of the valley. Flow from the spring, and hence the presence of the waterbody, is therefore dependent upon incident rainfall across this catchment area. At the time of survey the inflow and outflow rates from the pond were approximately equal at 0.3l/s. Outflow from the waterbody feeds a tributary watercourse of the Croxden Brook.

13.3.74 The remaining waterbody located outside the Site (Pond PD10) is situated on raised ground some 100m south of the Site at Cheadle Common. The pond has been excavated into a discrete deposit of boulder clay which underlies the area (sections 13.3.30 – 13.3.51). Water levels within this feature are dependent upon incident rainfall within the locality, and as such are hydraulically isolated from the wider water environment.

13.3.75 Within the existing quarry void, and restored workings adjacent to the Site, a number of former silt lagoons have been restored to open water features. The waterlevels within these features are perched above groundwater within the Triassic deposits and, as such are considered to be isolated from the surrounding water environment. The exceptions are ponds PD13 and PD14. These are formed within lower elevation areas within the Site and are expected to be in continuity with groundwater (as identified within the 1991 Assessment).

13.3.76 A total of four springs/seepages are located within 1 km of the Site. Two springs are located within the Croxden Brook Valley (S1 and S4), with two further springs located at the head of the Winnothdale Brook (S2 and S3).

13.3.77 The emergence of water at the head of the Winnothdale Brook occurs within an area of seepage (S3) south of Spring Farm (section 13.3.54), some 800m from the Site boundary. The outflow from this area has been measured (at the time of surveying) as some 0.3l/s.

13.3.78 Spring S2 feeds into the Winnothdale Brook downstream of Spring Cottages (NGR SK 0350 4028). This arises to the south of the valley feature described at section 13.3.38. In the area immediately downstream, discharge to the brook also occurs within an informal area of seepage. The flows from S2 and S3, together with this seepage area account for 80% of the flow within the brook under minimum flow conditions.

13.3.79 Spring (S4) is located within the Croxden Brook Valley at Brown Bank Farm, some 800m north-north-




east of the proposed development. As with Spring S1, S4 issues at the contact with the mudstone band occurring within the eastern flank of the Croxden Brook Valley. Flows from the spring are therefore dependent upon incident rainfall across the upper slopes of the valley to the east and hence hydraulically isolated from the Site. Emergent waters from the spring form the head of the Croxden Brook. At the time of survey the spring was observed to flow at some 0.1l/s.

Landfills

13.3.80 A radial search of the EA database indicates no active landfills are located within 1km of the Site boundary.

13.3.81 Two areas of historic landfill are indicated within the Site boundary (NGR 402701 341936 and NGR 402701 341936). These are believed to contain waste brick, tiles, stones and soils etc relating to historic manufacture processes at the Site.

13.3.82 The first of the aforementioned areas was located adjacent to the Old Counslow Road and has been excavated and processed in accordance with previous development proposals for the Site.

13.3.83 The second area lies to the east of the current plant Site. This will remain undisturbed by the extraction at the Site.

Hydrogeology

Overview

13.3.84 The nature of the hydrogeological regime encompassing the Site occurs as a result of the complex interaction between the various geological units in the area, associated faulting within these units, the local topography and the magnitude and occurrence of groundwater abstraction.

13.3.85 The Sherwood Sandstone Group, within which the quarry is situated, is classified a Principal Aquifer and is of regional importance in terms of water resources. In contrast, the underlying Coal Measures are generally of low hydraulic conductivity and hence offer limited aquifer potential.

13.3.86 The occurrence of groundwater within the Coal Measures is isolated within the interbedded sandstone and grit horizons occurring intermittently throughout the unit. Where such beds come into contact with the Sherwood Sandstone there is the potential for the two units to be in hydraulic continuity. However, due to the structure and lithology of the Coal Measures local to the Site, these strata are considered to form the effective base of the active aquifer within the Croxden Aquifer Block.

13.3.87 The hydraulic separation of the Sherwood Sandstone and Coal Measures strata is evidenced by information collected during drilling works on the Coal Measures adjacent to the contact with the Triassic deposits to the northwest of the Site. At two locations within this area, groundwater was found to be absent within the upper 70m of the Coal Measures; groundwater only being encountered when sandstone horizons of more significant thickness were intercepted at depth.

13.3.88 Within the Sherwood Sandstone Group, lower permeability horizons interbedded within sandstone and conglomerate units, results in a strongly anisotropic regime whereby vertical permeability is significantly lower than horizontal permeability. The limited vertical permeability often results in the localised perching of groundwater and the hydraulic separation between groundwater regimes vertically.

Regional Hydrogeology

13.3.89 Examination of the groundwater and surface water levels in the locality indicate that groundwater flow follows the general surface water drainage pattern for the area (i.e. towards the south-east). Superimposed upon this general direction of groundwater flow are localised variations resulting from the interaction between the groundwater and surface water environments comprising the system of glacially deepened valleys, the presence of faults (which may enhance or reduce aquifer permeability themselves, or result in the juxtaposition of strata of differing aquifer permeability), and from groundwater abstraction.

13.3.90 Where the aforementioned valleys intercept the watertable, the direction of flow occurs towards the valley with emergent groundwater providing baseflow to the watercourse of the valley. The ingress of




groundwater to these watercourses may also occur from perched springs emerging on contacts with lower permeability bands within strata comprising the flanks of the watercourse (e.g. springs S1 and S4). Such features will provide baseflow to the watercourse, as well as locally recharging the underlying aquifer.

13.3.91 To the northwest of the Site, the base of the Hawksmoor Formation occurs above the maximum level of the watertable such that the entire local thickness of the Permo-Triassic deposit is unsaturated. The section of dry deposit, underlain by impermeable Coal Measures strata, effectively separates the hydrogeological regime to the northwest from that within the Permo-Triassic deposit surrounding the Site.

13.3.92 The effect of faulting within the various geological strata on the hydrogeological regime is considered to be largely proportionate to the magnitude of fault displacement. The two dominant faults in the area (the Southern and Sandy Lane Faults) are traceable for several kilometres, and appear to exert significant control on the groundwater regime. The presence of these faults defines the eastern and southern boundaries of the aforementioned Croxden Aquifer Block.

Local Hydrogeology

Groundwater Levels and Temporal Groundwater Variation

13.3.93 The record of local groundwater levels and temporal behaviour presented within the 1991 Assessment has been updated using a combination of data obtained from a network of piezometers installed within the deposit encompassing the Site, groundwater level data from EA operated piezometers local to the Site, through field investigations and review of information collated during other hydrogeological investigations.

13.3.94 Groundwater levels local to the Site have been recorded since April 1996 within the network of piezometers installed by Tarmac Limited. The location of monitoring points are shown on Figure 9. Groundwater levels were initially collected at four piezometers; two installed within the southern area of the current quarry void (CR95-1 and “Weighbridge”); one installed to the east (CR95-4) and one to the northwest (CR95-3).

13.3.95 Monitoring of the initial series of four piezometers ceased in January 1997. Monitoring was recommenced in January 1999 following installation of five additional piezometers (CR98-1 to 5). Later in 1999 the scheme was expanded further with the inclusion of monitoring at a disused borehole located adjacent to the New Counslow Road (“Waterwell”) and a further single installation (CR99-05) drilled within the southern section of the existing quarry. Piezometers CR95-1 and “Weighbridge” were destroyed in period 1997-99, but monitoring has continued at CR95-3 and CR95-4. CR95-3 has been recorded as dry to 206mAOD throughout the monitoring period.

13.3.96 In 2001 monitoring was expanded to include two further piezometers located to the north of the Site, adjacent to the Cheadle – Alton road (CR01-01 and CR01-02).

13.3.97 Data elucidating the nature of long-term groundwater level variations is provided from an EA groundwater monitoring piezometer located at Sunnybank Farm, located some 400m south of the Site.

13.3.98 Groundwater hydrographs depicting the variation in groundwater levels at the Site for the period 1996 –2011, together with the data derived from the EA’s Sunnybank Farm monitoring point, are presented at Figure 10a and 10b.

13.3.99 Examination of the long-term monitoring data recorded at the EA’s Sunnybank Farm monitoring point show long-term maximum groundwater levels recorded in the summer of 2001, and long-term minimum levels in winter 1997/98. The maximum levels recorded in 2001 are reflective of the prolonged higher than average rainfall between 1998 and 2000, and the significantly higher rainfall experienced in 2000 (30% above the LTA). This general pattern is also observed in monitoring data recorded at the quarry, with maximum groundwater levels recorded in June 2001. For the purposes of assessment these levels are assumed to be indicative of the long-term maximum conditions likely to be experienced at the Site.

13.3.100 The monitoring scheme at the quarry was not operational during the winter of 1997/98 (when the long-term minimum levels were recorded at the Sunnybank Farm monitoring point). An estimate of the minimum groundwater levels likely to be encountered at the Site have been calculated by comparison of the minimum levels recorded within the Site piezometers, to the level recorded at the Sunnybank




Farm monitoring point at the corresponding time.

13.3.101 The minimum levels recorded within the Site piezometers occurred during January 1999. The level recorded at the Sunnybank Farm monitoring point in January 1999 occurred some 2.5m above the long-term minimum (1997/8). It is therefore apparent that a more representative long-term minimum level at the Site would occur some 2.5m below the minimum levels recorded to date at the Site.

Groundwater Flow Direction

13.3.102 The foregoing updated record of groundwater levels have been used to prepare refined contour plots depicting the derived groundwater head distribution for the area encompassing the Site. These are presented for both maximum and minimum groundwater elevation conditions at Figures 11a and 11b.

13.3.103 The minimum contour plot uses the minimum collected data recorded within the Site piezometers. As discussed above, long-term minimum groundwater levels are likely to reside some 2.5m below those depicted at Figure 11b.

13.3.104 Beneath the Site, the pattern of groundwater flow indicates a generally constant gradient to the south-east. To the south-east of the Site the groundwater gradient steepens and adopts a more easterly component across the Sandy Lane Fault into the Croxden Brook Valley. The steepening of the groundwater gradient across the fault will result from one of, or any combination of, the following scenarios (which are considered in more detail below):

• The proximity to the point of groundwater discharge. i.e. the Croxden Brook.

• The faulted juxtaposition of strata of differing permeability.

• The fault acting as a barrier to groundwater flow.

13.3.105 In the vicinity of Lightoaks and Coneydale Farms, groundwater elevation data is collected at either side of the fault and close to the Croxden Brook (CR98-4 and CR98-5). Here, the groundwater level adjacent to the Croxden Brook resides some 15m below the base of the watercourse i.e. the watercourse is perched above groundwater and is not receiving groundwater discharge. Under minimum flow conditions, discharge within the upper reaches of the watercourse are principally maintained by (perched) spring flows from the eastern flank.

13.3.106 Groundwater levels on either side of the fault at Lightoaks Farm occur within differing stratigraphic levels within the same unit (the Hawksmoor Formation). It is therefore considered unlikely that the observed magnitude of change in groundwater gradient would result from differing hydraulic properties of the strata on either side of the fault.

13.3.107 The groundwater hydrographs for the aforementioned piezometers indicate differing patterns of groundwater variation on either side of the fault i.e. suggesting a separation in hydrogeological regimes. Data from the piezometer to the east of the fault (CR98-5), when compared to that from the piezometer located to the west and within the Croxden Aquifer Block (CR98-4), displays a more subdued (and delayed) response to rainfall and a significantly lower seasonal variation in waterlevels.

13.3.108 It is considered that when viewed together, the foregoing factors indicate that the change in gradient across the fault is most likely to result from the fault acting as a barrier to groundwater flow.

13.3.109 To the south of this area at Great Gate, pump testing of the boreholes located on either side of the fault indicate that the hydraulic properties of the fault may be variable. During testing, a degree of drawdown was observed to cross the fault, indicating some degree of continuity across the fault13.

13.3.110 The presented contour plots have been prepared omitting the data recorded at piezometer CR01-01. This is installed into the Coal Measures strata on the northwestern featheredge of the Triassic deposit. The Triassic deposit in this area is dry and no significant groundwater ingress was recorded during the installation of the borehole (no sandstone horizons were encountered within the Coal Measures [section 2.8.1]). Thus recorded levels within CR01-01 are considered to isolated from, and unrepresentative of, the regional watertable.

13.3.111 The pattern of groundwater flow correlates well with that presented within the 1991 Assessment.

13 Personal communication with Severn Trent Water PLC. October 2003.




Marginally higher groundwater levels are indicated within the northern and western sections of the Site, although predicted peak groundwater levels are largely consistent in the areas remaining for extraction. Within the remaining extraction areas, in accordance with the current planning permission for the Site, the standoff of 3m from the watertable shown at Figure 11A will be maintained.

Relationship between Ground and Surface Water Levels

13.3.112 The extended data period and inclusion of additional monitoring points has allowed details to be refined for the groundwater regime encompassing the Site. This includes consideration of the interaction between the groundwater and surface water environment in the proximity of the local streams.

13.3.113 As described above, the direction of groundwater flow within the Croxden Aquifer Block is generally to the south-east. Comparison of stage data for the watercourses local to the Site, with groundwater levels within the Croxden Aquifer Block, indicate that the watercourses have the potential to derive flow from groundwater within the block throughout the year.

13.3.114 The discussion presented above indicates a significant degree of separation between groundwater levels within the Croxden Aquifer Block and the levels of groundwater to the east of the Sandy Lane Fault and encompassing the Croxden Brook. The elevation of the base of the Croxden Brook resides some 15m above the groundwater level encompassing the watercourse. It is therefore apparent that any flows within the brook will be perched above the groundwater environment and dependent upon ingress from the series of perched springs on the eastern flank of the valley within its upper reaches.

13.3.115 The Winnothdale Brook therefore appears to be the principle outlet for groundwater from the Croxden Aquifer Block. Flow gauging undertaken as part of previous assessment in the locality indicates that the majority of flow within the watercourse derives from a series of springs/seepage in the vicinity of Spring Farm (NGR SK 0325 4033) with little or no ingress between this point and the confluence with the Croxden Brook.

13.3.116 Comparison of interpolated groundwater levels with the basal level of the watercourse within the Winnothdale Valley correlates with the results of accretion profiling undertaken as part of this assessment. Groundwater levels in the upper reaches of the watercourse coincide with the valley floor and thus provide groundwater discharge to the watercourse.

13.3.117 To the east of Spring Farm, groundwater levels gradually drop to a level significantly below the base of the watercourse. Within this section, the watercourse is considered likely to be losing flow to groundwater (or at least not gaining flow). Upon the eastern most section of watercourse, the streambed comprises lower permeability alluvial deposits. It is likely that these will serve to isolate the watercourse from the underlying groundwater environment.

13.3.118 Two waterbodies (PD1 and PD10) are located outside the quarry boundary but within the Croxden Aquifer Block. Pond PD1 is located to the east of the Site at Coneydale Farm, Pond PD10 is located at Cheadle Common to the west of the quarry entrance. Comparison of the anticipated groundwater levels in the vicinity of PD1, and the elevation of the waterbody itself, indicate that groundwater is likely to be discharged to the waterbody under maximum elevation conditions, and lost from the waterbody to groundwater under minimum elevation conditions.

13.3.119 Pond PD10 is a man-made feature excavated into an area of boulder clay situated upon Triassic deposits. The groundwater level within the Triassic deposits occurs some 55m below the base of the waterbody. It is therefore apparent that the pond is a perched feature, isolated from the surrounding groundwater environment within the Croxden Aquifer Block.

Hydraulic Conductivity

13.3.120 An estimate of the hydraulic conductivity of the Freehay deposit has been made using Hazen14 analysis, using grain size distribution data obtained from the deposit worked at Croxden Quarry. Hazen’s method is based upon the principle that a relationship exists between the particle size distribution and its hydraulic conductivity. A summary of the results of analysis is presented below in Table 13.4.

14 “Some Physical Properties of Sand and Gravels”. Hazen A., 1983, Massachusetts State Board of Heath, 24th Annual Report.




Table 13.4: Summary of Hazen derived hydraulic cond uctivity values

Description Hydraulic Conductivity (metres/day)

Average 12

Minimum 5

Maximum 32

13.3.121 The values of hydraulic conductivity derived from Hazen analysis are considered to be unrepresentatively high for the in-situ deposit. This is a frequently observed phenomenon and is considered to principally result from the testing of a disturbed sample i.e. the analyses failing to accommodate the effects of clay/silt binding and compaction, which occur within the in-situ aquifer.

13.3.122 Experience from other similar sites, and the results of recent research15, indicate that the permeability calculated by the Hazen technique produces values that are typically some ten times greater than actual field values.

13.3.123 For comparison, values of hydraulic conductivity derived from pump test data have also been obtained for a number of sources installed within the Hawksmoor Formation in the locality. These are presented in summary at Table 13.5.

Table 13.5: Summary of pump test derived hydraulic conductivity values

Source Grid Ref. Transmissivity (m2/day)

Hydraulic Conductivity (metres/day)

Tarmac Croxden Quarry Borehole

403700 341300

288 5

Great Gate Boreholes 405200 339900 600 9

Notes: The presented values for Hydraulic Conductivity are calculated based upon a saturated thickness of aquifer equivalent to the thickness of the Triassic deposit (65m beneath the eastern section of the Site).

13.3.124 The Hawksmoor Formation displays a marked anisotropic character. The interbedded nature of the deposit results in a significantly reduced vertical permeability compared to that horizontally. The limited vertical permeability results in a delay of some six months between the annual period of enhanced recharge to the aquifer (November – February), and the subsequent response of groundwater levels.

13.3.125 The vertical permeability for the Hawksmoor Formation has previously been calculated as 0.11m/d16 i.e. two orders of magnitude lower than the horizontal permeability. It is therefore apparent that the ingress of groundwater to the quarry workings will be primarily focused laterally with a subordinate component vertically.

Groundwater and Surface Water Abstractors

13.3.126 A radial search of the EA licencing database and the District Council Environmental Health Department records of private water supplies has been undertaken to update the record of abstraction presented within the 1991 Assessment. The search presented herein has been undertaken for a 2km radius from the remaining extraction areas. Each of the abstractions identified within this update were previously included as part of 1991 Assessment.

13.3.127 Full details of the ground and surface water abstractions, identified within the 2km radius, are presented at Table 13.6. The locations are illustrated on Figure 12, Appendix 13.1.

13.3.128 A total of eleven abstractions (two licensed) exist within a 2km radius of the Site. These abstractions are made either directly from groundwater or related springs. The majority of abstractions are located to the south-east and east of the Site, within the Croxden Brook Valley. The exception is the two abstractions made from the Coal Measures to the west of the Site at Cheadle.

13.3.129 Three of the abstractions were historically licensed (Brown Banks, Light Oaks and Coneydale Farms)

15 “Aquifer permeability testing in sand and gravel ”. J Goodman. Doctorate thesis. University of Birmingham. 2000. 16

“Calculation of water balance for Croxden and Winnothdale Brooks”. Environmental Simulation International Limited. 2000.




but are now unregulated following implementation of the Water Act 2003 (abstractions less than 20m3/d are now exempt).

13.3.130 The closest abstraction located outside the quarry boundary (Brown Bank Farm [No. U3/U4 on Figure 12]) is made from a spring catchpit located some 450m from the closest area of extraction (Phase 2). This abstraction is currently used for both domestic and general agricultural purposes at the farm (although the farm is also on mains water).

13.3.131 The second closest abstraction (Lightoaks Farm [No. U1 on Figure 12]) is situated some 560m from the closest extraction area (Phase 3). Although currently disused, the abstracted water is normally used for the general supply of water at the farm.

13.3.132 The third groundwater abstraction (Coneydale Farm [No. U2 on Figure 12]) is made from a borehole located some 650m from the closest of the areas remaining for extraction (Phase 3). This abstraction is currently used for the general supply of water at both Coneydale and Lightoaks Farms, and for domestic supply at Coneydale Farm. The two farms are currently managed by a single farmer.

13.3.133 The closest licensed abstraction is made by Tarmac Limited within the Site boundary (No. L1 on Figure 12), where pumping is made for the purposes of mineral washing and dust suppression within the quarry.

13.3.134 The second licensed abstraction is made by Severn Trent Water Plc from a series of public water supply boreholes at Great Gate. A total of five boreholes are licenced at this location, located both to the east and west of the Sandy Lane Fault. Two of the boreholes are interconnected by an inclined borehole such that they operate as a single source.

13.3.135 The abstraction from the Great Gates site has been licenced to allow for supply to both the mains water network and for augmentation discharge to the adjacent Croxden Brook. This is operated in response to the EA AMP program to address issues of public water supply abstraction and low flows within certain identified watercourses.

13.3.136 The Site is located within Zone 3 (Total Catchment) of the EA defined catchment for the Great Gate boreholes. Implicit within this definition, is that groundwater in the vicinity of Croxden Quarry has been interpreted to provide a supply to the abstraction at Great Gate.

13.3.137 A review of the Local Council records indicates that eight Private Water Supplies are located within the 2km search area. Three of these abstractions have been described above (Brownbank Farm, Lightoaks Farm and Coneydale Farm). The remaining abstractions are made from either perched features located to the east of the Croxden Brook Valley (P1) and to the north of the Dimmings Dale Valley (P2 and P6), or from the Coal Measures strata to the west of the Site (P7 and P8) and as such are regarded to be hydraulically separated from the Site.




Table 13.6: Details of licenced abstractions and pr ivate water supplies within 2km of the proposed dev elopment

ID Licence No. Licence holder Address Source Easting Northing Use of Water

Depth of source (m)

Licenced Abstraction

L1 03/28/31/0009 Tarmac Quarry Products Ltd. Croxden Quarry Borehole 403700 341300 Industrial, Commercial - Mineral washing.

43.6

L2&L3 03/28/31/0017 Severn Trent Water Ltd

Greatgate BH A Borehole 405240 339950 Potable public water supply and environmental improvement (augmentation)

Greatgate BH B,C&D Borehole 405380 340010

Greatgate BH E Borehole 405360 340010

Unregulated Abstraction (less than 20m 3/d)

U1/P3 Not provided Lightoaks Farm, Cheadle Borehole 404400 341200 General Agriculture and Domestic 24.38

U2/P4 Not provided Coneydale Farm, Sandy Lane. Borehole 404400 340900 General Agriculture and Domestic 13.71

U3 Not provided Brown Bank Farm, Sandy Bank.

Catchpit 404200 342200 General Agriculture and Domestic

U4/P5 Catchpit 404100 342100

Private Water Supplies

P1 n/a Not provided New Farm Spring 405200 341800 Private water supply (<10m3/d).

P2 n/a Not provided Dimmings Dale Spring 404900 343400 Private water supply (single).

P6 n/a Not provided The Old Furnace Spring 404300 343700 Private water supply (single).

P7 n/a Not provided Public Well, Eaves Lane Well 401141 341913 Private water supply (single).

P8 n/a Not provided Gibraltar Farm Spring 401862 343453 Private water supply (>10m3/d).




Conceptual Hydrogeological Model

13.3.138 The data presented within this section has informed the development of a refined conceptual model, which describes the existing hydrogeological and hydrological regimes operating in the vicinity of the Site.

13.3.139 The economic mineral extracted at Croxden Quarry (Freehay Member of the Sherwood Sandstone Group) lies within the Croxden Aquifer Block. This is bounded on the eastern and southern sides by faults.

13.3.140 The Sherwood Sandstone aquifer is underlain by less permeable Carboniferous Coal Measures strata. The contact between the two units dips from outcrop in the River Tean Valley towards the south-east.

13.3.141 The thickness of Sherwood Sandstone aquifer increases from zero thickness at the Coal Measures outcrop northwest of the Site, to a thickness in excess of 100m at the aforementioned faults in the south and east. The pinching out of the Sherwood Sandstone forms the northwestern boundary for the aquifer block.

13.3.142 The occurrence of groundwater within the defined aquifer block is primarily attributable to incident rainfall, with minimal transfer expected across the faulted contact from the area to the north-east.

13.3.143 In accordance with the dip of geological strata, the direction of groundwater flow within the economic mineral occurs to the south and south-east. The principle point of discharge of groundwater from the aquifer block is expected to occur as spring flows to the Winnothdale Brook.

13.3.144 The principle abstraction made from the Croxden Aquifer Block is taken via the series of Public Water Supply boreholes installed at Great Gates. A proportion of the abstracted water is returned to the adjacent Croxden Brook to alleviate issues of low flow.

13.3.145 Comparison with groundwater levels and flow direction presented within the 1991 Assessment indicates the extraction has not resulted in an appreciable alteration in the local groundwater regime from that predicted within the previous assessment.

13.4 Impact Assessment and Mitigation Measures

Introduction

13.4.1 Baseline assessment has facilitated the formulation of a conceptual model describing the groundwater and surface water system operating within and around the Site, including the interaction with the existing development.

13.4.2 The Planning Application is being made for a time extension of 10 years to the Permitted Development. This would allow extraction of the remaining reserves of some 7.1 m/t until 2023.

13.4.3 The conceptual model is now applied in an assessment of the potential impacts upon the water environment posed by this time extension to the permitted development.

13.4.4 Where significant potential for adverse impact is identified, mitigation measures have been suggested.

13.4.5 Both specific “stand-alone” mitigation measures and those incorporated into the working scheme for the Site are described.

Generic Potential Impacts

13.4.6 As with the majority of quarrying operations, working and subsequent restoration of the remaining extraction areas has the potential to impact upon the water environment in the following primary ways:

i). Potential modification of extant groundwater levels and flow rates surrounding mineral extraction areas (during and following works).

ii). Potential for derogation of surface water quantity.

iii). Potential derogation of existing groundwater quality.

iv). Potential for derogation of surface water quality.

v). Potential increase of flooding risk.




13.4.7 In turn, these primary impacts may lead to secondary impacts, including:

i). Potential impact upon volumes/quality of water available to existing groundwater and/or surface water abstractions.

ii). Potential impact upon floral and/or faunal habitats as a result of flow derogation within surface watercourses/wetland areas.

13.4.8 These potential issues are discussed in more detail below.

Potential for Impact upon the Groundwater Flow Regi me and Groundwater Resources

Revised Estimation of Peak Groundwater Levels

13.4.9 The pattern of groundwater flow and predicted elevation data has been refined following the inclusion of additional monitoring points. The additional groundwater level data collected since the 1991 Assessment indicates marginally higher groundwater levels to be present within the northern and western sections of the Site, however the predicted peak groundwater levels are largely consistent in the areas of future extraction, with those predicted in the 1991 Assessment (below the base of the Freehay Member).

13.4.10 As identified within the 1991 Assessment - the clean water lagoon and southern informal drainage area remain the only areas of water where groundwater is exposed to evaporative losses. The southern drainage area is to be utilised as a future silt settlement area and hence will be restored to a level above the extant watertable (serving to further reduce potential evaporative loss from the aquifer).

Groundwater Flow Regime and Groundwater Resources

13.4.11 Following on from the above discussion, the remaining mineral extraction is to be made above the watertable and in accordance with the existing planning permission for the Site. Review of the hydrogeological regime prevailing at the Site indicates, that extending the period over which the permitted reserves can be worked, has no potential to cause a negative effect on the availability of groundwater resources in the locality.

13.4.12 The proposed time extension will increase the period over when abstraction is made to provide lagoon top-up water for the mineral processing system. This will result in extending the period when groundwater abstraction will remain at current levels.

13.4.13 The closest groundwater abstraction (Brownbank Farm, Figure 12 No. U3/U4) is located at NGR SK 0410 4210, some 450m from the closest remaining extraction area. This abstraction, together with the private water supplies P1 and P2 are made from perched springs expected to be fed by rainfall falling in the area to the north and east. These abstractions are also separated from the Croxden Aquifer Block by the Sandy Lane Fault.

13.4.14 Similarly the second closest groundwater abstraction (Lightoaks Farm, Figure 12 No. U1) is located at NGR SK 0440 4120, some 300m from the Site boundary. The abstraction is made from the Hawksmoor Formation but is located outside the Croxden Aquifer Block, being again separated from the proposed working area by the Sandy Lane Fault. This is also the case for the abstraction points P6 and P7 (located 1.8km and 1.6km from the Site boundary respectively).

13.4.15 The closest abstraction to Site made from within the Croxden Aquifer Block is located at Coneydale Farm (NGR SK 0440 4090, Figure 12 No. U2). This is located some 800m from the quarry abstraction point.

13.4.16 The remaining abstraction from the Croxden Aquifer Block is made at the Great Gates borehole No. 1 (Figure 12 No. L2). This is located some 2km from the quarry abstraction point.

13.4.17 Abstraction has been made from the quarry borehole without recorded detriment to any of the identified abstractors in the locality and there are no proposals to increase the level of abstraction. It is therefore considered that the required extension to the period of abstraction from the quarry borehole, to enable the processing of extracted mineral, will not significantly affect the availability of groundwater resources for existing users in the locality.




Potential for Impact upon Flow within Surface Water courses and Surface Water Resources

13.4.18 The conceptual model identifies the Winnothdale Brook as the principle point of groundwater discharge from the Croxden Aquifer Block. In comparison, the Croxden Brook has been shown to be isolated from groundwater local to the Site.

13.4.19 The Winnothdale Brook is fed by groundwater discharge emanating from the Croxden Aquifer Block in the vicinity of Spring Farm (NGR SK 0325 4033). At this location, the closest area of groundwater ingress to the watercourse is located some 700m from the Site boundary (950m from the quarry borehole).

13.4.20 The proposed extension period for mineral extraction and related groundwater abstraction from the quarry borehole is not expected to alter the prevailing pattern of groundwater discharge to the Winnothdale Brook. It is therefore considered that the potential for measurable impact on water levels or flows within the Winnothdale Brook (or other local watercourses), resultant from the proposed time extension, is negligible.

13.4.21 The other surface water features (ponds) identified within the locality are similarly expected to remain unaltered as a result of the proposed time extension.

13.4.22 Notwithstanding the above, due to the importance of the Winnothdale Brook as a tributary to the Croxden Brook and in accordance with modern monitoring protocols, it is recommended that the monitoring of flows within the Winnothdale Brook is initiated to operate concurrently with the remaining mineral extraction. Outline details of the requirements for such monitoring are presented in section 13.5 of this chapter.

Potential for Impact upon Groundwater and Surface W ater Quality

13.4.23 As with similar quarry workings, the operation of plant and machinery within the Site carries the associated risk of pollutants entering the groundwater system.

13.4.24 In the quarry context, pollutant risks are generally confined to accidental hydrocarbon spillage or leakage.

13.4.25 In principle, the risk of potentially polluting spillage associated with the continued extraction is no greater than that associated with the numerous similar quarry workings currently operating throughout the region.

13.4.26 The following measures are already implemented at the Site:

i). Fuel and waste oil is stored in bunded tanks.

ii). Refuelling takes place from bunded fuel storage areas.

iii). Oil spill kits are kept at the Site.

iv). Procedures to prevent spills and minimise their event in they occur are included in the Site Environmental Management System.

13.4.27 It is considered that these measures provide adequate safeguards to prevent hydrocarbons leaking into groundwater in normal circumstances.

13.4.28 As described previously, groundwater within the sand and gravel aquifer encompassing the Site discharges to the Winnothdale Brook to the south. It is therefore apparent that through the aforementioned measures for the protection of groundwater quality these will also serve to prevent the derogation of surface water quality in the locality.

Potential for Impact upon Flooding Characteristics

13.4.29 A Flood Risk Assessment (FRA) has been undertaken, as required by Planning Policy Statement 25. The FRA is presented in Appendix 13.2.

13.4.30 The FRA has looked at the various possible sources of flooding, and considered climate change where appropriate.

13.4.31 The conclusion of the FRA is that the proposed time extension will not result in a significant potential




for increasing flood risk off-site, and that the potential for flooding within the Site remains negligible (assuming continuation of existing drainage procedures).

Potential for Impact upon Ecological Resources

13.4.32 The foregoing assessment has demonstrated that there is expected to be no derogation of groundwater levels or flow as a consequence of the proposed time extension to mineral workings above the water-table. It is therefore apparent that the development has no potential to impact upon the Statutorily Protected Sites identified within the vicinity (Cecilly Brook LNR and Dimmings Dale and the Ranger SSSI).

13.5 Outline Proposals for Monitoring

13.5.1 The results of impact assessment indicate that the proposed time extension for mineral extraction, and subsequent restoration, will have no significant direct or indirect hydrogeological or hydrological impacts upon the water environment.

13.5.2 Due to the sensitivity of watercourses in the locality, it is recommended that the current scheme of monitoring is expanded to include measurement of flows within the Winnothdale Brook (subject to agreement with the relevant landowner).

13.5.3 The Winnothdale Brook has been identified as the principle point of groundwater discharge from the Croxden Aquifer Block. The purpose of monitoring flows on the Brook will be to allow a more complete assessment of the availability of groundwater resources to be made for the local aquifer, and henceforth will feed into any future development plans for the locality.

13.5.4 It is recommended that the existing network of 10 piezometers currently monitored by Tarmac Limited shall form the basis of the monitoring scheme. The monitoring of flows within the Winnothdale Brook will comprise monthly flow gauging and installation of a gauge board equipped with a data-logger, to establish an approximate stage–discharge relationship for the downstream section of the watercourse.

13.6 Summary

13.6.1 Tarmac Limited are applying for a time extension of ten years to their existing planning permission, expiring in November 2013, to extract the remaining permitted mineral reserves and to restore Croxden Quarry (the Site), Nr Cheadle, Staffordshire.

13.6.2 The current planning permission was issued following completion of an Environmental Impact Assessment which included a Hydrological Assessment (the 1991 Assessment). Under the existing planning permission for the Site, extraction is permitted to a level of three metres above the “natural winter watertable” (Condition 57).

13.6.3 The remaining reserves are located within three discrete phase areas totalling 34ha. The extraction of the remaining mineral will follow the pattern established within the current quarry workings and in accordance with the aforementioned stand-off from the watertable.

13.6.4 This document has considered the potential for impact, with respect to groundwater and surface water systems at and around the Site, from extending the period of the existing planning permission by a further ten years.

13.6.5 The Site is situated upon an area of elevated ground comprising the eastern flank of the River Tean Valley. The local area to the east and south of the Site is intersected by valleys associated with the Croxden Brook, located approximately 500metres (m) to the east of the Site boundary, and the Winnothdale Brook, situated approximately 800m to the south. These valleys link together near the village of Great Gate some 1.2km south-east of the Site.

13.6.6 The land surface within the current quarry void generally increases from 180mAOD in the south-east to 220mAOD to the northwest. These levels are equivalent to between 35m and 50m below the original land surface.

13.6.7 The Site is underlain by Permo-Triassic deposits of the Hawksmoor Formation (Sherwood Sandstone Group). The economic mineral extracted at the Site comprise the Freehay Member of the Hawksmoor Formation. The Freehay Member is a conglomeratic deposit interbedded with subordinate, well




cemented, sandstone bands and infrequent mudstone bands.

13.6.8 The Triassic deposits unconformably overlie Carboniferous Coal Measures strata. The Coal Measures comprise a significant thickness of interbedded sandstones, siltstones, mudstones and coal seams. The western boundary of the Site defines a lateral geological boundary between the outcrop of Triassic deposits to the south-east and Coal Measures strata to the northwest (within the River Tean Valley).

13.6.9 The contact between the two units is interpreted to form the base of the local aquifer. This occurs as a generally south-easterly dipping surface from an elevation of 210mAOD at the outcrop area to the northwest of the Site, to some 20mAOD beneath the Triassic deposits in the area to the south-east.

13.6.10 Local to the Site the Hawksmoor Formation strata outcrops as a roughly triangular area defined by the lateral extent of Triassic strata to the northwest, and by a series of interconnected faults to the south (the Southern Fault) and east (the Sandy Lane Fault). This defined area is referred to as the Croxden Aquifer Block.

13.6.11 The Hawksmoor Formation is locally affected by minor faulting within the larger fault block as described above. The most significant of these faults from a hydrogeological perspective crosses the southern section of the Site, oriented towards springs identified within the Winnothdale Brook Valley to the south.

13.6.12 Groundwater levels local to the Site have been recorded by the mineral operators since April 1996. Data elucidating the nature of longer-term groundwater variations within the Croxden Aquifer Block have been examined using data obtained for the EA’s Sunnybank Farm monitoring point (located some 400m south of the Site). This has been operational for some 26 years.

13.6.13 In accordance with the data presented within the 1991 Assessment, the recent hydrometric monitoring data indicate groundwater flow within the Croxden aquifer Block to occur to the south and south-east.

13.6.14 In the area to the south-east of the Site the gradient of variation steepens towards the Croxden Brook Valley and across the Sandy Lane Fault. Hydrogeological data collected on either side of this fault indicate that the aforementioned change in gradient is most likely to result from the fault acting as a barrier to groundwater flow.

13.6.15 Comparison of the longer-term data collected at Sunnybank Farm to the Site specific data, has allowed a range of long-term maximum and minimum groundwater levels to be calculated for the Site. The refined contour plots correlate with the 1991 Assessment and confirm that extraction will remain above the watertable in accordance with the current planning permission.

13.6.16 The Site is located within the drainage basin for the River Dove. Locally, the site is situated within the catchment area for the Croxden and Winnothdale Brooks. The Croxden Brook is cited within the Environment Agency’s National Environment Plan (now AMP5) due to problematic low flows within the watercourse. The Winnothdale Brook forms a tributary to the Croxden Brook, the two watercourses linking upstream of Great Gate.

13.6.17 The Croxden Brook is located to the east of the Sandy Lane Fault and outside the Croxden Aquifer Block. For the reach of the watercourse to the east of the Site the Croxden Brook has been shown to be perched above groundwater, with flows being maintained by runoff and discharge from perched springs emerging on the eastern flank of the valley i.e. hydraulically independent of the Croxden Aquifer Block.

13.6.18 The range in flow conditions within the Croxden Brook at Great Gate vary between zero and some 100l/s. Under minimum flow conditions the reach of the Croxden Brook upstream of the confluence with the Winnothdale Brook becomes dry, such that flows within the Croxden Brook downstream are dependent upon outflow from the Winnothdale Brook.

13.6.19 The Winnothdale Brook is located within the southern section of the Croxden Aquifer Block and is fed by groundwater from within the aquifer block. The range in flow conditions within the Winnothdale Brook have been recorded between zero and 29l/s. Ingress to the Winnothdale Brook has been shown to occur primarily within 500m of the head of the watercourse in the vicinity of Spring Farm. Under minimum flow conditions ingress within this area accounts for some 80% of the total flow from the watercourse.

13.6.20 Seventeen waterbodies have been identified within a 1km radius of the Site boundary. The majority of these are located within the existing Site and within the Croxden Brook Valley to the east. One feature




outside the Site boundary (PD1) has been identified as being in continuity with groundwater within the Croxden Aquifer Block. All other features have been shown not to be dependent upon groundwater levels within the area encompassing the Site.

13.6.21 Under prevailing conditions, it is anticipated that PD1 gains water from groundwater under maximum elevation conditions, whilst losing to the aquifer under minimum conditions. PD1 was included within the 1991 Assessment and remains unaffected.

13.6.22 A total of four springs are located within a 1km radius of the Site boundary (2 within the Croxden Brook Valley and 2 within the Winnothdale Brook Valley). The springs within the Croxden Brook Valley (S1 and S4) issue at a contact with a mapped mudstone band within the Hollington Formation outside the Croxden Aquifer Block. These are perched features fed by rainfall falling on the raised ground to the north and east of the valley and hence are considered to be independent of groundwater within the Croxden Aquifer Block.

13.6.23 Springs S2 and S3 comprise the principle points of discharge from the Croxden Aquifer Block to the Winnothdale Brook. Under moderate low flow conditions the combined discharge from these features has been shown to account for the majority of flow within the watercourse prior to the confluence with the Croxden Brook. Under extreme low flow conditions the flow within both the Croxden and Winnothdale Brooks is zero.

13.6.24 The presence and nature of water abstraction in the vicinity of the Site has been investigated to update the record of abstraction presented within the 1991 Assessment. A total of eleven abstractions from groundwater are made within a 2km radius of the Site. Each of the identified abstractions were previously included as part of the 1991 Assessment.

13.6.25 Three of the abstractions are made from the Croxden Aquifer Block (L1, U2 and L3). The closest abstraction to the remaining extraction areas is L1. This is made by Tarmac Limited from a borehole within the eastern section of the Site. Abstraction is made for mineral washing and dust suppression.

13.6.26 Abstraction U2 is made from a borehole at Coneydale Farm. This is located some 650m from the closest of the remaining extraction areas. Abstraction is made for general use at the farm and domestic supply.

13.6.27 The final abstraction is made by Severn Trent Water PLC (STW) from a series of Public Water Supply boreholes at Great Gate. These are installed both to the east and west of the Sandy Lane Fault, some 1.3km south-east of the Site boundary. As part of the EA AMP5 program, STW currently provide augmentation discharge to the adjacent Croxden Brook, to improve flow conditions downstream of Great Gate abstraction point.

13.6.28 The remaining areas of mineral extraction are to be made above the natural winter watertable defined for the Site (Figure 11A) and in accordance with the existing planning permission for the Site. Following a review of the hydrogeological regime for the area encompassing the Site, it has been shown that extending the period over which the permitted reserves can be worked has no significant potential to affect existing water users, flows within watercourses, ecological sites or levels within waterbodies in the locality.

13.6.29 The time extension will increase the period for when abstraction is made for mineral processing. However, as there are no plans to alter the rate of abstraction and the current abstraction is made without detriment to existing users, waterfeatures or identified ecological sites, it is considered that the extended period for abstraction, to allow processing of the extracted material, will continue to have negligible impact on the water environment in the locality.

13.6.30 In accordance with current planning requirements a Flood Risk Assessment has been undertaken. This has indicated that the proposed time extension for extraction has negligible potential for increasing flood risk in the locality.

13.6.31 In recognition of the sensitivity of watercourses in the locality it is recommended that the current scheme of groundwater monitoring is continued to operate concurrently with the proposed development. The Winnothdale Brook has been identified as a principle point of discharge from the Croxden Aquifer Block. It is therefore recommended that the scheme is expanded to include collection of flow data for the Winnothdale Brook (subject to agreement with relevant landowners). Collection of this data will allow more complete assessment of groundwater resources within the aquifer block and hence aid any future assessment relating to development in the locality.




13.7 Conclusions

13.7.1 A comprehensive investigation has been undertaken to assess the potential for the proposed time extension for extraction of permitted reserves, and subsequent restoration works, to impact upon the water environment.

13.7.2 The assessment has involved the correlation and examination of hydrogeological and hydrological data supplied by the Environment Agency, together with site-specific data collected from within, and local to, the Site itself. These data have been used to refine the conceptual model for the locality, developed as part of the original EIA conducted for the Site.

13.7.3 The study concludes that the time extension for extraction (and related abstraction for mineral processing) has insignificant potential to cause any negative impact in the locality.

13.7.4 It is however recognised that Site is located within a sensitive location with regard to flows within the Winnothdale Brook (a tributary to the Croxden Brook). Therefore, an outline scheme of monitoring has been presented which is intended to provide further baseline monitoring data for the locality, with a view to aiding assessment for any future development at the Site.




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13 hydrogeological and hydrological assessment

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