Groundwater Is An Important Natural Resource Biology Essay

Groundwater is an of import natural resource for agricultural, industrial, imbibing and domestic intents. Over 35 of public H2O supply in England and in Wales and 70 % of H2O supply in south and east England comes from groundwater resources ( Stuart and Smedley, 2009 ) . It has long been seen as a comparatively pure natural resource that is stored in subsurface aquifers and its quality under menace from anthropogenetic influences. Chemical quality alterations occur chiefly through direct input of anthropogenetic substances during groundwater abstraction, attendant alterations in the groundwater flow government and in procedures of unreal recharge ( Stuart and Smedley, 2009 ) .

Carbonate stones form of import subsurface aquifers in many countries of the universe, particularly north-west Europe where the Chalk is a primary beginning of drinkable H2O ( Bloomfield, 1997 ) . Chalks are major aquifers widely exploited in the United Kingdom for public H2O supply. Chalk groundwater plays an of import function in the care of flow both in national and international hydrological systems ( Ander et al. , 2004 ) . The bulk of public supply Chalk boreholes are situated along river vales normally to work the shallow deepness to the H2O tabular array and higher transmissivity in the river vale ( Stuart and Smedley, 2009 ) . The Chalk is a fractured stone holding really powdered matrix. The nature of its matrix makes much of the H2O held within the chalk pores non able to be drained by gravitation. Aquifer belongingss of the Chalk are controlled by breaks and larger pores ( Bloomfield, 1997 ) . This gives rise to a extremely transmissive, but comparatively low – storage aquifer that is at changeless hazard from taint by sea – H2O or agrochemicals ( Jones and Robins, 1999 ) . Alternatively, as the break system becomes less hydraulicly important, the matrix porousness is envisaged to progressively act upon solute motion ( Bloomfield, 1997 ) .

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“ Hydrogeochemical development of groundwater from its composing as rainfall, is dependent on the complex interplay of the procedures taking topographic point in the unsaturated zone and overlying composing and the composing of the aquifer and bing groundwater ” ( Ander et al. , 2004 ) . Therefore, cognition of the chemical composing of pore H2O reflects both the beginning of the groundwater and the manner in which the original composing has been modified by diagenetic reactions with either stone or organic affair ( Hancock and Skinner, 2000 ) . Pore H2O fills the interstices of deposits and sedimentary stones. Chloride, Na and Ca are the most common ions found in pore H2O of deeply buried carbonate deposits ( such as Chalk ) , while other elements are of lesser sum. Fluid commixture and reactions with carbonate minerals and clays exert an of import control on the composing of pore H2O in Chalk aquifers. Invasion of saline Waterss into pore H2O besides influences the part of groundwater motion in the matrix of the Chalk. Due to the powdered nature of the Chalk matrix, little size of its pore pharynxs and high pore H2O suctions, the pores can non to the full drain. However, since pore H2O force per unit areas are less than atmospheric force per unit area, the chalk above the H2O tabular array is described as unsaturated ( Ander et al. , 2004 ) .

The survey country, Morestead Road Waste Water Treatment Works ( WWTW ) , is located on the Chalk downland of Hampshire, E of Winchester, and is split into two parts by the M3 expressway ( Mortimore, 2004 ) . Pore H2O samples extracted from nucleus from boreholes within the survey country will be investigated analytically for groundwater quality alterations in the Chalk aquifer profile. Besides, this survey seeks to set up the relationship between H2O degree alterations and wastewater discharge, to see whether consistence exists in the clip taken to make the H2O tabular array as it ‘s known about Chalk aquifers.

STUDY AREA

Morestead is a little small town located near the South Downs in the metropolis of Winchester territory of Hampshire. It lies 5 kilometer sou’-east from its county town, Winchester. The site ‘s oldest portion is situated West of the M3 expressway, north eastern incline of St. Catherine ‘s Hill ( SU 486 277 ) and boreholes from here are designated by MWC. This location sits on the steep incline of the hill taking due norths down to the River Itchen via a little watercourse that drains westward out of Morestead Road WWTW ponds. The site ‘s other portion is situated E of the M3 expressway towards the northern wings of Twyford Down ( SU 492 277 ) with boreholes widening from here labelled MWE. The Morestead WWTW is positioned due souths off an east – west vale formed by an eroding along the crest of the Winchester Anticline. High land environing this local vale rises to and above 140mAOD.

Brydones map 2

Figure 1: Geologic map of Chalk zones within and around Winchester, Hampshire. It shows the domal construction of the Winchester Anticline with an east – west axis immersing both east and west, organizing a pericline. The corresponding Chalk Formations are clearly indicated by the pointer marks, while the ruddy points are: the Morestead WWTW sites and St. Catherine ‘s Hill WTW ( adapted from Mortimore, 2004 ) .

1.3 GEOLOGY OF THE AREA

Winchester country provides a uninterrupted exposure through the in-between and late chalk of the Cretaceous ( Turonian to Campanian phases ) along the E, through the M3 expressway. Exposure of the upper Turonian phase can be seen near the Bar End, while the Coniacian and Santonian phases exposed through Twyford Down and partially near Shawford. Adjacent to the country of Morestead Road WWTW, film editings of the M3 expressway show the strata dip and general geological construction in the White Chalk Subgroup, peculiarly the Lewes Nodular Chalk, and the Seaford Chalf Formations ( Mortimore, 2004 ) . A northern dip of 150 was identified on the northern limb of Winchester Anticline, measured on the pilotage Marls in the Lewes Nodular Chalk exposed under the Spitfire Chalk Formation ( dunking north ) . The uppermost New Pit Chalk of the motorway film editings of the Twyford Down, expose the full Lewes Nodular Chalk and radical beds of the Seaford Chalk Formation. The Southerham Marl dip measured in Twyford Down is 60 – 80 sou’-west on the southern limb of the Winchester Anticline ( Mortimore, 2004 ) .

Despite good expressway subdivisions in the Chalk, few exposures of the lower formations organizing the bedrock chalk in the country are around New Morstead Road WWTW. Previous probes of five shallow deepness ( 10 to 15m ) rotary – cored boreholes ( October, 1996, logged by Professor Rory Mortimore ) at Morestead Road WWTW indicated, in downwards sequence, the presence of basal Holywell Nodular Chalk including the Plenus Marls and Melbourn Rock, and the Zig Zag Chalk Formation, known as the White Bed ( Mortimore, 2004 ) .

Brydone ( 1912 ) zonary map of the Chalk of Hampshire was based on fossil grounds and demo the site to situated on Holaster Subglobosus Zone ( now loosely referred to as Zig Zag Chalk Formation ) and the Inoceramus Labiatus Zone ( known as Holywell Nodular Chalk Formation ) . He besides numbered the exposures of chalk where he obtained fossil grounds for the zones measured above. Three of such numbered vicinities ( 57, 79, and 80 and 117 ) are still of relevant to the Morestead Road probes.

Degree centigrades: UsersChristopherDesktopLiman DataData for LimanMorestead Rd MapsMorestead_new_geol_crop.JPG

Figure 1.2: Generalised geology of Morestead Road WWTW site, demoing the different borehole locations ( adapted from British Geological Society ( BGS ) Map 299 Winchester, 2001 ) .

1.4 REGIONAL STRATIGRAPHY AND HYDROGEOLOGY

Originally, the UK chalk was divided into three, viz. : the Upper, Middle and Lower Chalk. The nature of this wide distribution incorporated important thicknesses of Chalk, for which recent function has provided subdivision of these Formations into mappable units of member position ( Bristow et al. , 1998 ) . These members are chiefly defined into marker skylines such as marl bed, difficult evidences and flint beds. A combination of the marker skylines, coloring material, hardness, geomorphology and dodo content define typical features of each unit. Table 1.1 below show the relationship bing between the new and old stratigraphical categorizations with regard to the Southern Province.

Table1.1: Tabular relationship between old and new Chalk stratigraphy for the southern geological state adapted from Bristow et Al. ( 1997 )

The Hampshire Chalk H2O tabular array by and large follow a subdue signifier of topography with the unsaturated zone thicker under hills and dilutant in vale parts ( Allen at al. , 2009 ) . Chalk confined by Palaeogene strata have the Chalk piezometric surface non shown and limited informations from boreholes indicate a gradient towards the seashore. In Chalk aquifers, flow takes topographic point either via break flow of matrix flow or a combination of both. Vertical and horizontal flow constituents may be responsible for aquifer recharge through the unsaturated zone. Recharge procedures are likely to be dominated by the presence of permeable and impermeable skylines within the Chalk ( Stuart and Smedley, 2009 ) . The happening of impermeable beds besides helps to concentrate flow in certain countries.

Soil natural philosophies analysis from a farm near Winchester ( Bridget ‘s Farm ) , concluded that H2O motion preponderantly occur through all right pores of the Chalk matrix with merely a minor constituent happening through crevices ( Wellings, 1984 ) .

Lithology is an of import control on the transmissivity of the Chalk and the hydraulic belongingss of Chalk are greatly influenced by the presence of difficult evidences, flints and marl sets. Crevice zones in the Chalk by and large appear to be related to tabular flint sets in the Upper Chalk ( Entec, 2002 ) . Some karst characteristics have been observed in the Twyford film editings on the M3 expressway ( Hopson, 2000 ) .

The Upper Chalk is general considered a better aquifer than both the Middle and Lower Chalks. However, solution can increase the hydraulic belongingss of the Middle Chalk where it is exposed near the surface. The high marl content and limited break development of the lower Chalk makes it a poorer aquifer ( Giles and Lowings, 1990 ) .

Topography besides is a strong influencing factor on the hydrogeological system of Chalk aquifers. Outputs from boreholes in interfluves countries are by and large less than those in vales ( Allen et al. , 2009 ) .

Geological constructions, such as mistakes and creases, besides play both direct and indirect function in aquifer belongings development. Giles and Lowings ( 1990 ) suggested higher outputs along the axes of weather-beaten synclines instead than in anticlines.

The porousness of chalk varies between 5 % and 45 % and is dependent on the stratigraphy ( Bloomfield et al. , 1995 ) . The Upper Chalk of Southern England has an mean porousness 39 % , while the Middle Chalk and Lower Chalk are 28 % and 23 % severally ( Bloomfield et al. , 1995 ) . At Twyford, the Upper Chalk porousness of the Seaford Chalk is in the scope 38 – 50 % and that of the underlying Lewes Nodular Chalk is between 35 and 40 % ( Stuart et al. , 2008a ) .

A survey of artesian boreholes at Alresford ( in the Candover catchment ) by Headworth ( 1978 ) showed that a narrow zone at the top of the boreholes contributed the bulk of flow, with the staying aquifer supplying upward escape to a high transmissivity bed. At Twyford, bagger trial of a borehole found that the most of import flow skyline occurred in the zone widening 10m below the H2O tabular array, with diminishing values below this ( Stuart et al. , 2008a ) .

Transmissivity values are lower than 500m2 day-1 across the groundwater divide nearing the Weald in east Hampshire, reflecting the stratigraphy of the Chalk. Groundwater flow preponderantly occurs through the Lower Chalk ( less fractured ) and storage potency reduced as good. On the scarp incline towards the Thames Basin, in the North, transmissivity improves ( Allen et al. , 2009 ) .

1.5 INTRODUCTION TO THIS DISSERTATION

Chapter Two: LITERATURE REVIEW

2.1 PROPERTIES OF CHALK AQUIFERS

Chalk is a sedimentary stone with diagenetically altered chalky nannofossils representing its chief constituent. It is normally derived from chalky sludge of the ocean where food and temperature conditions of the surface Waterss favour chalky plankton ( Berger and Winterer, 1974 ) . The deepness of formation of halk sedimentations is controlled preponderantly by the solubility of dead remains of calcitic plankton in the ocean H2O, described as the Carbonate Compensation Depth ( CCD ) .

The presence and development of breaks in the Chalk, gives it the belongingss of an aquifer. The permeableness and specific output of the Chalk would be negligible without breaks. Furthermore, without the presence of solution sweetening of the breaks, the high transmissivity of the Chalk would non hold been possible, and without farther groundwater flow concentration and disintegration of chalk, karstic and conduits characteristics would non be observed. The Chalk frequently is referred to as possessing “ double porousness ” ( Price, 1987, Barker, 1991, Price et al. , 1993 ) . The matrix pores provides storage in a authoritative double porousness aquifer while the breaks provide the permeable tracts to allow groundwater flow. Movement of groundwater within the Chalk is more complex, i.e. high porousness ( produced by coccoliths ) is non readily drained, due to the really little pore pharynxs ( Price et al. , 1976 ) . Therefore effectual groundwater storage chiefly occurs within the break web and larger pores.

Woodland ( 1946 ) analyzing the hydrogeology of East Anglia identified the relation between transmissivity and topography. Ineson ( 1962 ) so estimated transmissivity from specific capacity informations and produced maps of transmissivity fluctuation over the Chalk. The most distinguishable characteristic of these was the correlativity or understanding of high transmissivity values with vale undersides, peculiarly at vale meetings. More late, renewed involvement in the regional distribution of aquifer belongingss have arisen, due to the development of numerical theoretical accounts ( e.g. Rushton et al. , 1989, Cross et al. , 1995 ) . The bulk of these theoretical accounts require information on aquifer belongingss from the interfluves every bit good as from the vale undersides.

Many factors have contributed to the development of aquifer belongingss within the Chalk. General topographic form of transmissivity fluctuation through a figure of procedures have developed, such as: groundwater flux concentration within vales ( Rhoades and Sinacori, 1941, Robinson, 1976, Owen and Robinson, 1978, Price 1987, Price et al. , 1993 ) ; Chalk construction ( Ineson, 1962, Water Resources Board, 1972, Price, 1987, Price et al. , 1993 ) ; and periglacial eroding, peculiarly within taliks ( Higgenbottom and Fookes, 1971, Williams, 1980, Gibbard, 1985, Williams, 1987, Younger, 1989 ) .

As described earlier ( see subdivision 1.4 ) , the Chalk petrology has an of import consequence on aquifer belongingss, particularly the presence of marl beds, flints or hardgrounds ( Price, 1987, Buckley et al. , 1989, Lowe, 1992, Mortimore, 1993, Bloomfield, 1997 ) . As can be seen in Figure 1.3, petrology and construction geomorphology, such as vales and disintegration enhanced breaks, promotes transmissivity in Chalk aquifers. Palaeogene, or other younger screen, can be influential in the development of solution characteristics and groundwater conduits, as can recent or historic presence of rivers, and periglacial activity ( Fagg, 1958, Atkinson and Smith, 1974, Walsh and Ockenden 1982, Price et al. , 1992, Banks et al. , 1995, MacDonald et al. , 1998, Lamont – Black and Mortimore, 1999 ) .

Figure 2.1: Some factors that contribute to the development of aquifer belongingss within the Chalk ( adapted from MacDonald, 2001 ) .

2.1.1 CHALK MATRIX

The frequent and good affiliated nature of the pores within Chalk matrix consequences in enhanced porousness but the peculiar little pore-throats causes really low permeableness ( Price et al. , 1993 ) . Average permeableness of 977 measured nucleus samples from the English Chalk was found to be 6.3 ten 10-4 m d-1 ( Allen et al. , 1997 ) .

Bloomfield ( 1997 ) identified two chief diagenetic procedures to be responsible for Chalk porousness even though porousness in Chalk is thought to be variable and affected by petrology but chiefly determined by the grade and nature of diagenesis. The two chief diagenetic procedures are ; mechanical compression ( physical rearrangement of fragments to organize denser constructions ) and pressure solution or chemical compression ( disintegration and re-precipitation of minerals ) . Following the initial accretion of biogenic deposits, porousness is believed to be between 70 and 80 % ( Hancock, 1993 ) . The consequence of bioturbation reduces porousness to about 60 % ( Bloomfield et al. , 1995 ) , while later diagenetic procedures and mechanical comapaction, after entombment of about 250m, reduces the porousness to approximately 35 to 50 % ( Hancock, 1993 ) . As the overburden additions, chemical compression becomes more of import than mechanical compression and entombment of about 1000 m reduces porousness to about 30 – 40 % ( Bloomfield, 1997, Hancock, 1993 ) .

Chemical compression processes have a more variable consequence on porousness than mechanical compression and depend upon pore H2O chemical science, petrology and clay mineral content ( Bloomfield, 1997 ) . Allen et Al. ( 1997 ) evaluated porousnesss of four countries of the English Chalk ( Table 2.1 )

Table 2.1: Porosity estimations in four countries of the English Chalk ( as adapted from Allen et Al. 1997 )

Porosity %

Soap

Minute

Average

Northern England Upper Chalk

45.3

3.3

35.4

Norther England Middle Chalk

31.4

6.7

18.9

Southern England Middle Chalk

35.9

20.5

28.4

Southern England Lower Chalk

46.5

9.7

22.9

Thames and Chilterns Lower Chalk

52.6

9.5

31.4

Thames and Chilterns Lower Chalk

39.5

11.6

26.6

Southern England and Thames and Chilterns Upper Chalk

48.9

5.6

38.8

East Anglia Upper Chalk

55.5

24.1

38.4

East Anglia Middle Chalk

47.8

18.4

34.3

2.2 REGIONAL DISTRIBUTION OF AQUIFER PROPERTIES

The four parts of involvement are: ( 1 ) Southern ; ( 2 ) the Thames Basin ( including the North Downs ) ; ( 3 ) East Anglia ; and ( 4 ) Yorkshire and Lincolnshire. MacDonald ( 2001 ) showed that the transmissivity distribution, over the four parts above, is loosely similar.

Giles and Lowings ( 1990 ) suggested a connexion between turn uping in the Hampshire country and high transmissivity. However, lower transmissivity countries of Dorset and the South Downs have been subjected to more foldable than either Hampshire or Salisbury Plain. The lowest average transmissivity values are found in East Norfolk and East Suffolk, London countries. These three countries of the Chalk aquifer have considerable screen and are confined in some topographic points.

2.2.1 CHALK PROPERTIES IN VALLEYS AND INTERFLUVES

By and large, it is accepted that borehole outputs in the Chalk are higher in vales than over interfluves and that transmissivities tend to follow in similar form ( e.g. Woodland, 1946, Ineson, 1962 ) . One easy ways to prove transmissivity fluctuation in vales compared to interfluve is to analyze the correlativity between transmissivity and deepness to rest – H2O – degree ( RWL ) . This is because RWLs are known to be shallower in vales than interfluves.

Robinson ( 1976 ) predicted transmissivity fluctuations in the country under low H2O tabular array conditions utilizing factors such as primary distance from winter fluxing watercourses modified by deepness to minimum RWL and the Upper and Middle Chalk thickness. A good correlativity between the predicted consequence and those from high quality pumping trial, carried out under minimal H2O table conditions, was achieved.

2.2.2 CHALK IN CONFINED AND UNCONFINED CONDITIONS

MacDonald ( 2001 ) utilizing database to analyze fluctuations in both transmissivity and storage coefficient, with the grade of parturiency of the aquifer, observed that the storage coefficient exhibited important differences between measurings taken in confined and unconfined conditions. He found that the median for confined pumping trials was 0.0006 and 0.008 for unconfined trials. Semi – confined trials had values mediate. Valuess from the confined Chalk agreed favorably with elaborate research into Chalk storage undertaken by Lewis et Al. ( 1993 ) . They calculated the specific storage of the Chalk to be 1.5 ten 10-5 Garand rifle, which when integrated over a 100m thickness of Chalk aquifer, gives a storage coefficient of 0.0015 for confined Chalk.

Storage coefficient estimated from unconfined pumping trials show similarity to those estimated from groundwater – degree recession analysis by Lewis et Al. ( 1993 ) . For which the top 30 m of concentrated Chalk, was estimated for storage coefficient to be 0.005 to 0.05, comparing favorably with the unconfined pumping trial inter-quartile scope of 0.0028 to 0.017.

Identified difference between confined and unconfined storage elucidates the comparative importance of elastic storage in the Chalk. Chalk aquifer are extremely compressible ( Carter and Mallard, 1974, Price et al. , 1993 ) explicating the high estimations of specific storage by Lewis et Al. ( 1993 ) and the corresponding high values of storage coefficient evaluated from confined pumping trials. Specific output is limited by little proportion of Chalk pores in unconfined aquifers that can run out under gravitation – less than 1 % of the Chalk majority volume ( Price et al. , 1976, Price, 1987 ) , for which the limited volume of groundwater is stored in breaks. Therefore, under unconfined conditions, the elastic storage is still comparatively of import.

Understanding th fluctuation in aquifer belongingss is cardinal to patterning groundwater happening and taint motion tracts within the Chalk aquifer ( MacDonald, 2001 ) .

2.3 UNSATURATED ZONE FLOW PROCESSES IN CHALK

Much argument has occurred on how much flow in unsaturated zone in the Chalk is through crevices and breaks compared to matrix. Smith et Al. ( 1970 ) suggested about 85 % of flow in unsaturated zone occur preponderantly via the matrix for which he introduced the construct of Piston flow ( H2O within the unsaturated zone is bit by bit displaced by new recharge given rise to the oldest and deepest groundwaters to be discharged through the underside of the aquifer system ) , accounting for the rapid response of rainfall regardless of the slow migration of tritium. An norm of 1 m/year was calculated for the downward motion rate through unsaturated zone by Smith et Al. ( 1970 ) .

More recent tracer surveies such as those carried out by Welling ( 1984 ) , Barraclough et Al. ( 1994 ) , Haria et Al. ( 2003 ) and Van den Daele et Al. ( 2007 ) have shown a peak concentration move through zones of unsaturation at about 1 m/year. Besides, near surface measuring of dirt wet content and matric potency ( e.g. Wellings and Cooper, 1983, Ireson et al. , 2006 ) have been used to look into recharge mechanisms for which a decision of flow through the matrix was determined as the dominant procedure, with crevice flow initiated at some sites where the matric potency is beyond some certain threshold.

Wellings and Cooper ( 1983 ) confirmed three of these sites studied at Hampshire show matrix flow as the dominant procedure while crevice were initiated during wet periods. However, this position was questioned by Mahmood-ul-Hassan ( 2002 ) on the footing that the frequence of informations aggregation affected the consequences Welling and Cooper ( 1983 ) obtained. They demonstrated that utilizing higher frequence informations, rapid alterations in H2O content and matric potency, in a affair of hours following rainfall, indicated discriminatory flow through crevices and breaks as against a low frequence informations that indicated matrix flow merely at the same clip.

Barraclough et Al. ( 1994 ) transporting out a tracer probe of the top 6 m of the unsaturated zone in Berkshire did non place crevice flow. However, the absence of tritium extremum at 15 – 20 m deepness suggested that perpendicular flow may be more dominant traveling deeper into the unsaturated zone.

Price et Al. ( 2000 ) mensurating Chalk block belongingss, suggested that crevice flow can be generated at any deepness within the unsaturated zone, peculiarly in countries where matrix hydraulic conduction is low. Unsaturated zone crevice flow was thought to be initiated in narrow parts of crevices and where more likely to arise near the H2O tabular array with the lowest pore suctions.

2.4 HYDROGEOCHEMISTRY OF THE CHALK AQUIFER

Groundwater chemical composings are controlled by a figure of factors, the principal of which is carbonate reaction. It occurs quickly prima to a strong buffering on the groundwater composing. Geological constructions and enduring forms are influential in commanding groundwater flow and flow rates ensuing in chemical fluctuations, both with deepness and laterally, peculiarly in the confined near – coastal parts of the Chalk aquifer.

Unconfined aquifers by and large have groundwater emanating from them to be aerophilic with ascertained concentrations of dissolved O up to saturated values of around 10 mg l-1 and redox potencies ( Eh ) frequently above 300 millivolt ( Adams, 2008 ) . Groundwaters from unconfined Hampshire Chalk have small fluctuation in major-ion composing and are chiefly of Ca-HCO3 type ( typical of Chalk groundwater ) .

2.4.1 Major Components

Concentration of Ca and HCO3 in the Chalk aquifers are of an order of magnitude higher than the other major ions and have a proportionally narrower scope of distribution ( Stuart and Smedley, 2009 ) . This narrow concentration scope for Ca ( 94 – 144mg L-1 ) indicates a rapid solution of calcite to its solubility bounds. Figure 2.2 shows a secret plan of major ions distribution in the Chalk aquifer of the Hampshire country

Stuart and Smedley ( 2009 ) measured Cl ( Cl ) concentration, within the Hampshire country, to be between the scopes of 12.9 – 23.5 mg L-1 with a median of 18 mg L-1 utilizing statistical methods. No obvious spacial tendency was observed for Cl concentration. Besides, Mg ( Mg ) concentrations were low ( averaging 1.98mg L-1 ) as was expected for unconfined Chalk groundwater. This Mg was thought to be most likely reflecting input from reactions with clay minerals in the Palaeogene strata.

Potassium ( K ) concentration within the Hampshire country ( besides determined by Stuart and Smedley, 2009 ) , range from below the sensing bounds of 3.53 milligrams L-1 holding an mean value of 1.33mg L-1. This concentration of K as with Mg was suggested to hold increased as consequence of reactions with clay minerals in the overlying Palaeogene deposits or with clay minerals in the Chalk. Concentration of Sulphates is by and large low ( with an norm of 11.8 mg L-1 ) and has similarities with those found in Dorset Chalk ( Shand et al. 2007 ) . Sulphate was suggested to hold been derived from atmospheric inputs or from pyrite beginnings. This is because pyrites are known to be present in difficult evidences in the Chalk and besides likely to be really much nowadays in Palaeogene sedimentations.

Nitrate concentrations have value of around 6.5 mg L-1 as N ( N ) , comparing moderately good with groundwaters from the Chalk ( Shand et al. , 2007 ) . NO2-N and NH4-N concentrations are both uniformly low and below sensing bounds in most countries within the Hampshire ( 0.001 mg L-1 and 0.066 milligrams L-1 for NO2-N and NH4-N concentrations severally ) . Concentration secret plan for major ions distribution in the Hampshire Chalk aquifer is shown in figure 2.2.

The measured dissolved O ( DO ) content, by Stuart and Smedley ( 2009 ) , are besides low ( averaging 0.8 mg L-1 ) , similar to that observed from the Dorset Chalk ( Edmunds et al. , 2002 ) . Dirt reactions by and large produce DO but are enhanced by pollution input beginnings ( e.g. landfills and slurry cavities ) . The concentration of Si ( Si ) is comparatively unvarying all through the Hampshire part, with scopes of approximately 4.6 to 9.4 milligrams L-1. Si in Chalk groundwater can be derived from clay minerals or flint within the Chalk matrix ( Stuart and Smedley, 2009 ) .

Figure 2.2: Plot of major ions distribution in the Chalk aquifer of the Hampshire country ( adapted from Stuart and Smedley, 2009 ) .

2.4.2 TRACE Elementss

A major hint component controlled by carbonate reaction is strontium ( Sr ) . It varies between 200 and 300 g L-1 in groundwater at outcrops but reaches up to 16 milligrams L-1 in confined aquifer with close propinquity to coastal countries ( Adams, 2008 ) . Sr concentration addition can be linked to saline invasion. A similar enrichment in Sr has been recorded in deep Chalk boreholes elsewhere in Britain by Edmunds et Al. ( 1992 ) . Sr concentration of around 20 milligram L-1 has been recorded in pore H2O from Chalk of 500 m deepness at Trunch Norfolk ( Bath and Edmunds, 1981 ) .

Stuart and Smedley ( 2009 ) analyzing the concentration of P ( P ) in the Hampshire country, observed that P vary widely over the country between a scope of 10 – 193 g L-1 with an norm of 19 g L-1. In the Chalk groundwater likely beginnings of P include phosphate minerals, particularly those of difficult evidences and besides exchangeable P from Fe oxides. Alternative, while beginning for P concentration addition can be linked to inorganic and organic fertilisers, no evident correlativity exist between P and other indexs of agricultural pollution such as NO3.

Stuart and Smedley ( 2009 ) besides estimated the concentration of F ( F ) to be by and large low ( averaging 105 g L-1 ) , with the highest values observed in groundwaters emanating from below the Palaeogene screen in the South of the Hampshire country. As with P, F are thought to arise from phosphate mineral ( fluoroapatite ) , present in difficult evidences and marl skylines in the Chalk. Bromine ( Br ) concentrations were observed to be lowest along groundwater divides. Iodine ( I ) are besides low in the cardinal portion of the Hampshire country. Of the alkalic metals, Li ( Li ) concentration ranges between 0.54 – 1.84 g L-1, with an mean value of 0.83 g L-1.

Adams ( 2008 ) suggested that the fluctuation of Br ( Br ) in groundwater suggest that additions are specifically related to saline invasion into coastal countries. Groundwater from unconfined aquifers by and large does hold low concentrations of Br ( less than 0.1 mg L-1 ) . They besides observed that in unconfined aquifers, Iron ( Fe ) and Manganese ( Mn ) concentration are by and large low due to oxidizing conditions. This they said increased when the groundwater becomes basically anaerobiotic under confined conditions, with the greatest addition seen in Fe ( in an surplus of 1 mg L-1 ) . Both are thought to be derived from natural disintegration under cut downing status, chiefly from Fe and manganese oxides.

Under near impersonal conditions, measured concentrations of many hint metals are low in Chalk groundwaters ( Admas, 2008 ) . Concentrations of aluminum ( Al ) are by and large below the bound of sensing and are typically present in low concentrations in Chalk groundwater due to the alumina-silicate minerals being ill soluble at circum-neutral pH ( Stuart and Smedley, 2009 ) . The maximal sensing bounds for Cd ( Cd ) concentration were below 0.5 g L-1 ( which is below sensing bound ) . Cadmium is most likely to hold been adsorbed to oxide surfaces. Zn concentration was found to be highest in Chalk outcrop country about Basingstoke but was by and large of an mean value of 11.5 g L-1 ( Stuart and Smedley, 2008 ) . Zn occurs as a hint component in calcite and clays and has higher concentrations at impersonal pH. Because it is a common industrial metal, anthropogenetic input may originate when significantly near to urban countries and landfills. Arsenic ( As ) concentration where besides found to be by and large low within the Hampshire country ( less than 2 g L-1 ) throughout both Chalk aquifers ( unconfined and confined ) ( Adams, 2008 ) .

2.5 TREATED EFFLUENT DISCHARGE

The Morestead WWTW is the largest return to land H2O within the Chalk in England ( Facey, 2005 ) . For many old ages it has been a pattern to dispatch treated waste H2O wastewaters to Chalk at a figure of inland sewerage intervention works in Hampshire. Subsurface waste H2O intervention and wastewater dispersion refers to the application of partly treated waste H2O to the subsurface, with infiltration and infiltration happening via the vadose zone or unsaturated zone and later into the concentrated zone before eventually making the implicit in groundwater ( Siegrist et al. , 2000 ) . Depth to the unsaturated zone can potentially impact hydraulic map ( hence the purification procedure ) by act uponing the dirt H2O content, media surface country, aeration position and the hydraulic keeping clip ( Van Cuyt et al. , 2001 ) .

Southern Water Authority in 1975, embarked on a programme of probe to determine the extent and nature of groundwater taint of the Morestead route WWTW and other of their intervention works. This probe focused on analyzing interstitial H2O quality, chemical microbiological and micro pollutant measuring in pore H2O and groundwater of the Chalk in Winchester country.

In the Morestead route WWTW, the dry conditions flow is 8000 M3 / d. Sewage or waste H2O is treated by deposit and is distributed by gravitation to reload ditches and lagunas ( Otterbourne, 1990 ) . Boreholes that supply H2O to the populace are situated on the southern wing of a pericline on top of the outcrop of the Lower and Middle Chalk. The motion of groundwater is by and large towards the West ( Otterbourne, 1990 ) . Water quality values selected from a figure of boreholes within the recharge country and way of outflowing flow can be seen in table 2.3.

Examined pore H2O components revealed that taint within the investigated boreholes extends every bit far as 85 metres below the H2O tabular array where hydraulic burden was tantamount to 20 mm/d in utilized recharge countries. Sewage outflowing concentration were in the scope of 65 to 83 % alimentary remotion in the Winchester country ( Otterbourne, 1990 ) . Besides, the oxidization of treated wastewater eliminated any procedures of N remotion, which was thought to be the likely ground for the loss of dissolved C, utilised in the microbiological procedure of denitrification. The laguna H2O beginning is provided mostly by primary outflowing recharge but consequences from Table 2.3, validates pollution happening from failure of old ditch system near the laguna ( Outterbourne, 1990 ) . Microbial remotion such as fecal bacteriums and virus is wholly eliminated within these sites boundaries.

Table 2.3: Groundwater chemical quality of Winchester site with the mean values in milligrammes per liter ( adapted from Otterbourne, 1990 ) .

Borehole Location

NH3

NO2

NO3

PO4

Chlorine

Bacillus

Doctor

A

Nitrogen

Nitrogen

Phosphorus

A

A

C

A

R Area South 1

6.3

0.03

2.7

1.9

65

0.64

7.3

R Area North 2

2.2

0.05

9.3

0.7

61

0.54

4.8

Experimental Area 3

1.9

0.03

0.7

0.1

58

0.5

3.6

R Area boundary 4

2.8

0.01

0.1

0.03

65

0.56

Lagoon

4.2

0.08

2.8

2.9

71

0.8

9.2

Lagoon flood

0.8

0.05

4.9

1.1

64

0.65

4.3

Effluent

26.4

0.15

0.9

5.1

83

1

5.1

2.5.1 EFFLUENT DISPERSAL TECHIQUES IN THE HAMPSHIRE AREA

All treated waste H2O wastewaters depart really radically from the ideal pure silt free H2O used in most research into Chalk aquifer recharge. Primary wastewaters are normally known to do the least pollution but ever present peculiar troubles in dispersion. A figure of soakaway methods employed in the Hampshire country are discussed in the subsequent subdivisions below.

2.5.1.1 LAND Spread

Land distributing secret plan laid out in countries underlain by Middle and Lower Chalk of the Morestead route WWTW helping in Winchester, was subjected to primary wastewater of hapless quality. Consequences obtained show that the steeper gradients, greater than 1:25, were unsuitable for proposed method of disposal with outflowing fluxing quickly downhill and short-circuiting big countries of land ( Otterbourne, 1990 ) . With even shallower gradients, the flow took discriminatory waies across the secret plan without soaking into the land go forthing the floras clogged with fungus and died. Otterbourne ( 1990 ) observed that outflowing C degrees were greater than 15 mg/ cubic decimeter induced sewerage fungus growing, reasoning that land spreading is non a method that can be used for poorer quality primary wastewater. This degree of intervention besides does non enable the benefits of denitrification to be obtained.

2.5.1.2 EXCAVATED DITCHES

Effluents are discharged into a series of trapezoidal ditches excavated through the top dirt deep into weather-beaten Chalk. This method has been applied in the Morestead route WWTW for about 100 old ages ( Figure 2.4 ) . In excavated ditches, wastewater is discharged into the highest of a series of contoured ditches on the land of inclines up to 1:10 and moved from the ditch to ditch until all has soaked away ( Otterbourne, 1990 ) . Since the intervention at Morestead route is of a primary nature and the colony armored combat vehicles are frequently hydraulicly overloaded, the standard even of this intervention is hapless. Research into the capacity of the ditches at Morestead route showed that there was decay in public presentation of all the ditches with clip as they became silted up.

hypertext transfer protocol: //upload.wikimedia.org/wikipedia/commons/0/06/Morestead_Sewage_Farm_-_geograph.org.uk_-_57146.jpg

Figure 2.4: The Green ditch form of Morestead route WWTW allows for treated H2O to ooze back into the Chalk aquifer ( adapted from Facey, 2005 )

2.5.1.3 SOAKAWAY LAGOONS

The care civilization of soakaway lagunas, i.e. wastewater must be given conventional primary and secondary colony before discharge and rotary motion of the lagunas to let recovery, make it by and large non favoured every bit good as the jeopardy nowadays should person should fall in them. Tests were nevertheless taken at Alresford works in 1981 during Reconstruction of the Gallic drain for to the full treated wastewater from the plants ( Otterbourne, 1990 ) . At the beginning the method was satisfactory in covering with all emerging wastewater from the work but quickly declined as the capacity increased.

2.5.1.4 FRENCH DRAIN SOAKAWAYS

Gallic drains have been the conventional agencies of wastewater disposal chiefly from infected armored combat vehicles for many old ages. It involves the discharge of wastewater to underground porous pipes, doing them attractive for wastewater disposal. Gallic drains are used at Alresford intervention works. Its general advantage is that they are non visually intrusive and there is much less smell issues than with other methods, helping there building non excessively far off from the population they serve. However, after 10 to 20 old ages, clogging of the soakaway may happen and hold to be replaced even though the wastewater has been treated to high quality criterions than from a infected armored combat vehicle ( Otterbourne, 1990 ) . Reconstruction of the Alresford drainage system in 1981 exposed some defects in the system in situ. The pores in the crushed rock packed evidences were wholly clogged, forestalling the free flow of wastewater to the Chalk aquifer ( Otterbourne, 1990 ) . Analysis of the pore stuffs showed that over 80 % were organic content probably to hold been derived from uneffective secondary deposit at the plants or from third biological activities taking topographic point within the land. In many instances it will be the capacity of the clotted crushed rock battalion to convey H2O, therefore regular resting and rotary motion of the Gallic drains is now the recognized pattern in the Hampshire works prosecuting in this type of soakaway.

2.6 EFFLUENT DISPOSAL SITES

Site and dirt associating factors required in the siting and design procedure for choosing an appropriate wastewater disposal site ( Geary, 1987, US EPA, 1980, Siegrist et al. , 2000, Dawes and Goonetilleke, 2003 ) , are given below:

topographic consideration, as in the site lift and incline ;

subsurface consideration, including the site dirt features and profile, groundwater tracts, deepness to the H2O tabular array, variableness and deepness to the restricting restrictive dirt bed ;

land country available for intervention of waste H2O and wastewater disposal ;

climatic conditions ( rainfall and temperature ) ;

frequence of implosion therapy ; and

location and distance to the specific topographic characteristic ( waterways and Wellss ) .

For long term credence of wastewater, it is necessary that these factors are put to consideration when designing and choosing a suited site for outflowing disposal systems. In choosing a suited disposal site of outflowing discharge from a WWTW, apprehension of the reservoirs ability to accept, dainty and scatter the wastewater is important. This is because the heterogenous nature of the dirt makes appraisal of a individual dirt parametric quantity incomprehensively suited ( Diack and Stott, 2001 ) . Therefore there is the demand for more scientific strict process when measuring dirt suitableness for treated wastewater disposal and remotion of of import pollutant. Some common subsurface wastewater disposal sites include ;

Trenchs

They are constructed as shallow diggings with a pierced pipe lay over crushed rock to enable the even distribution of applied wastewater. They are most suited where the dirts are reasonably permeable and remain unsaturated for sensible deepness below the surface ( Goonetilleke et al. , 1999 ) .

Bed System

It differs from the trench in that more than one outflowing distribution pipe is provided over a much wider country. This distribution web allows for smaller effectual country set-up necessary for outflowing distribution than those required for the trench system, doing the bed more suited enemy restricted site countries ( Carroll, 2005 ) .

Other subsurface disposal sites that are instead available for usage in countries where the trench and bed systems are considered inappropriate for supplying effectual wastewater dispersion, include the hill system ( designed to get the better of of scattering partly treated wastewater in countries of low dirt permeableness or high land H2O tabular array or bing chapped bedrock ) and evapotranspiration systems ( utilises climatic conditions to vaporize wastewater from shallow trenches combined with transpiration through the usage of flora planted specifically for the available H2O and alimentary use ) .

2.7 HYDROGRAPH OF CHALK AQUIFERS

Neuman ( 2007 ) analysed and combined 16 boreholes of deepnesss between 11.7 to 183.8 m to bring forth one maestro hydrograph for the Chalk in Winchester and South dikes ( Figure 2.5 and 2.6 ) . The ascertained H2O degrees ( Neumann, 2007 ) show seasonality and an implicit in tendency of comparatively low degrees around 1973 and 1976 to 1992 – 1997. However, utmost high events are seen during the winters of 1993/1994 and 2000/2001 ( Neumann, 2007 ) . This maestro hydrograph was established from March 1953 to October, 2004 ( Neumann ) .

Figure 2.5: Maestro Hydrograph for the Chalk in Hampshire and Wiltshire country ( adapted from Neumann, 2004 ) .

Figure 2.6: Water degree frequence classs per monthly period ( adapted from Neumann, 2004 ) .

Chapter THREE: FIELD SAMPLING AND ANALYTICAL METHODOLOGY

3.1 BOREHOLE LOCATIONS

Data chosen from 12 ( 12 ) borehole ( MWE02, MWE05, MWE06, MWE07, MWE08, MWE09, MWE11, MWE12, MWE13, MWE14, MWE15 and MWE16 ) locations are used for this research. The boreholes are in Winchester country, Hampshire part. The borehole locations ( see Figure 1.2, pp 6 ) are presented in Table 3.1 below.

Table 3.1: Position co-ordinates for each borehole studied within the Morestead WWTW site.

BOREHOLE NAME ( MWEXY )

Longitude

Latitude

EASTING

NORTHING

ELEVATION ( mbgl )

MWE02

-1.7E+308

-1.7E+308

449431

127705

54.66

MWE05

-1.7E+308

-1.7E+308

449852

128044

45.15

MWE06

-1.7E+308

-1.7E+308

449818

128316

53.45

MWE07

-1.7E+308

-1.7E+308

449578

128416

44.54

MWE08

-1.7E+308

-1.7E+308

449342

128226

44.42

MWE09

-1.7E+308

-1.7E+308

449257

128092

43.95

MWE11

-1.7E+308

-1.7E+308

449285

127968

42.98

MWE12

-1.7E+308

-1.7E+308

449380

127831

43.9

MWE13

-1.7E+308

-1.7E+308

449512

127842

44.99

MWE14

-1.7E+308

-1.7E+308

449761

127960

45.18

MWE15

-1.7E+308

-1.7E+308

449420

128143

44.12

MWE16

-1.7E+308

-1.7E+308

449597

128283

47.67

3.2 FIELD SAMPLING TECHNIQUE

Critical to the success of this research was the obtaining of nucleus samples. To repair the research country within a stratigraphic context, nucleus samples with unchanged Chalk and obtained porewater, for research lab testing, were collected and analysed. The percussion boring ( U100 ) technique ( a rugged, inexpensive sampling station that produces nucleus samples in most British clays typically to a great extent overconsolidated ) was used to intermittently core the new Alresford site.

For the Morestead route WWTW, air-flush rotary boring technique was employed alternatively of percussion boring to retrieve U100 samples, since it has been observed that the rotary coring method is far superior in the Chalk. The understanding by Southern Water to this extra cost was to give more dependable consequences. The Morestead Road was rotary cored, utilizing a mist flower method. Obtained nucleuss were transferred to a thin – walled PVC tubing, which were waxed and capped ( Munn, 2008 ) . This attack gave a close uninterrupted recovery and finally a much better apprehension of the site. On site, the nucleuss were stored in refrigerated containers before they were subsequently transferred in a refrigerated lorry to the refrigerated nucleus shop at the University of Brighton, Cockcroft Building. The nucleuss experienced a steady temperature of 2 – 80C after they were extracted ( Munn, 2008 ) .

3.3 REASON FOR CORE SAMPLES REFRIGERATION

Of extreme necessity is the confidence that the pore H2O extracted from the nucleus samples reflects every bit closely as possible in situ pore H2O that were really in the Formation. Several processes grossly alter pore H2O chemical science prior to analysis. Some of these are summarised as follows below:

diffusion of dissolved gases, such as ammonium hydroxide, oxides of N and semi – volatile organic compounds, down chemical gradients, as a map of temperature and partial force per unit areas. Therefore, decrease of the nucleus temperature causes a lessening in the rate at which H2O will vaporize ( Bohren, 1987 ) .

taint from the container or wadding stuffs, e.g. newspaper used to make full nothingnesss in the nucleus boxes / U100 tubings.

An premise of redress of most, if non all, of the mark analytes was made due to bioremediation, at the beginning of the survey ( Green et al. , 2001 ) . This was because bacteriums are known to of course metabolize a scope of compounds ( Stembal et al. , 2005, Benedict and Carlson, 1971, Topping, 1987 ) in order to obtain energy for respiration. Hence, decrease of the temperature of the nucleuss reduces drastically the hazard of samples being altered by biochemical procedures, guaranting that the pore H2O samples obtained are represent in situ Formation.

3.4 ANALYTICAL TECHNIQUES

3.4.1 CORE Logging AND POREWATER EXTRACTION TECHNIQUE

The initial research stage required the extraction of pore H2O from Chalk nucleuss extracted from the Morestead route site. This required that transverse taint of samples be kept at an absolute lower limit, and that maximal pore H2O recovery was achieved. In add-on to the above, it was deemed desirable that the obtained pore H2O underwent as small chemical change during centrifugation procedure and subsequent storage prior to analysis.

3.4.2 CORE Logging AND STORAGE TECHNIQUE

Before they were so transferred to the dirts research lab for logging, the gathered nucleuss were stored at temperatures between 2 and 80C. Heavy polyethylene bags were used to cover the surface upon which logging of the samples was to be carried out. These were renewed for each logged sample. After logging was successfully carried out, all implements used for logging were cleaned utilizing a properness combined detergent and bacteriacide. The nucleus logging was carried out by Professor Rory Mortimore, due to his expertness in this field. A geological cock was so used by Munn ( 2008 ) to render the Chalk down into pieces of about 5 millimeters diameter ready for centrifugation

3.5 PORE WATER EXTRACTION TECHNIQUE

Several attacks exist for pull outing pore H2O from dirts and porous stones, nevertheless no individual methodological analysis is appropriate to all applications. The pick of a method will hence depend on the peculiar purpose for which the survey was carried out. Therefore, description of the methodological analysis employed is really of import every bit good as saying the premises made. Generally, most field trying methods have been employed to construe both the inactive and dynamic position of Chalk pore H2O chemical science, without much relevancy paid to the Chalk H2O being sampled and its chemical responsiveness ( Wolt, 1994 ) .

Core sample pore H2O can be extracted by either a field-based attack ( such as tenseness sampling stations, monolith, and inactive sampling stations etc – all referred to as lysimeters ) or laboratory-based methods ( such as rhizona„? sampling stations, centrifugation, and force per unit area filtering ) . For this survey we focus on pore H2O extraction utilizing centrifugation technique. This is because centrifugation can be used to fractionate the pore H2O by choosing several centrifugation rates. Therefore, when increasing the centrifugal velocity, and hence the comparative centrifugal force ( RCF ) value, during several phases of dirt centrifugation, less available H2O may bit by bit be released and collected ( Tyler, 2000 ) .

3.5.1 Centrifugation

The usage of extractor method to pull out H2O from porous media has a long history. It was originally developed to set up “ moisture equivalent ” of a dirt, i.e. the wet content of a sample after the extra H2O has been reduced by centrifugation and brought to a province of capillary equilibrium with the applied force ( Nuclear Energy Agency, 2000 ) . Centrifuge technique relies on the difference in force per unit area developed across a sample transcending the capillary tenseness keeping the H2O in the pores.

Chalk nucleuss centrifugation was undertaken by Munn ( 2008 ) in order to pull out pore H2O without badly changing the pore H2O chemical science. In order to restrict gaseous exchange, both of the H2O itself and of any volatile or semi-volatile contaminations, refrigerated extractors were utilized. He used Rotanta 460R extractor in which the rotor arm and pail are in Computer Numerical Control ( CNC ) machined units. These made them able to defy the cyclic burdens that could be applied to them during centrifugation.

3.5.2 CENTRIFUGE SET – UP

In practise, it is unadvisable to cut down the temperature of a extractor below 120C as frost could be given to roll up on the extractor pails and rotor arm. This could potentially unbalance the rotor – arm during centrifugation, taking to unneeded wear ( Munn, 2008 ) . Icing is believed to happen due to cut down air – force per unit area in the centrifuge chamber during centrifugation caused by the motion of the rotor weaponries. The setup design developed by Nigel Munn for roll uping pore H2O, separated from the majority matrix during centrifugation, is shown in Figure 3.1. This head-space agreement was found to be effectual for the successful completion of the pore H2O extraction programme. Approximately 400 g of broken Chalk samples was placed into each container. The full agreement was so loaded into the centrifuge pails. Typically, the extractor was programmed to whirl at 2500rpm for a continuance of one hr at 120C. The diagram of the caput – infinite equipment is show in Figure 3.1.

Figure 3.1: Diagram of Head – infinite equipment demoing its gathering ( adapted from Munn, 2008 ) .

3.6 MEASUREMENT OF IONIC AND DETERMINAND CONCENTRATIONS

Inorganic cations, hint elements and sulfates were measured by inductively-coupled plasma optical-emission spectroscopy ( ICP-OES ) and anion species by machine-controlled colorimetric analysis at Southern Water ‘s research labs. Sample readying and analysis were carried out at the same research lab. Ionic balances for the analyses were within appreciable bounds and the preciseness for the hint elements were verified ( Munn, 2008 ) . pH was analysed by ion selective electrode ( ISE ) .

Concentration of ions and determinands in the concluding wastewater were evaluated from analytical consequences obtained from Southern Waters research lab.

All informations handling and secret plans were done utilizing Microsoft office Excel 2010 spreadsheet.

Chapter FOUR: Consequence

4.1 MORESTEAD ROAD BOREHOLE CORES

Core logging was carried out by Prof. Rory Mortimore ( Munn, 2008 ) . The rotary nucleus logging generated the undermentioned information:

litho- and biostratigraphical informations required to put the site and land profile in its right stratigraphical and structural geology puting. Besides, these informations will help in appraisal of the overall Chalk geology in relation to land permeableness.

The rotary method of boring provided first-class representative nucleuss that allowed for all lithological characteristics to be identified. Stratigraphic representation of encountered Formations during the rotary boring procedure is presented in the subsequent subdivision.

4.2 STRATIGAPHIC SEQUENCE

Several Formations where encountered during the boring of the Chalk at Morestead Road site. These include, Holywell, New Pit and Zig Zag. Stratigraphic representation of the Chalk at the Morestead Road site, from each borehole as a map of deepness interval, is presented in Table 4.1 below. Besides in figure 4.2, a elaborate stratigraphic sequence of drilled Chalk from borehole MWE05 is presented ( Munn, 2008 ) .

Drilled Chalk from borehole MWE05 occurred from 1.5 to 20.0 millimeters depth below land degree ( BGL ) . Designation of peculiar marker beds were less pronounced as this borehole was largely in the Zig Zag Chalk Formation ( Munn, 2008 ) .

Table 4.1: Stratigraphic Distribution of the Chalk at Morestead Road WWTW site

Boreholes

Depth-1 ( m )

Depth-2 ( m )

Stratigraphy

MWE03

3

9

Holywell

MWE03

9

35

Zig Zag

MWE05

1.5

20

Zig Zag

MWE08

1.5

24

Zig Zag

MWE10

3

12.2

Holywell

MWE10

12.2

39

Zig Zag

MWE16

1.5

27

Zig Zag

Degree centigrades: UsersChristopherDesktopLiman DataData for LimanBH MWE05.jpg

Figure 4.1: Drilled Chalk from Borehole MWE05 of the Morestead Road WWTW site, demoing encountered Formations and beds ( adapted from Munn, 2008 ) .

4.3 VARIATION – Time GRAPH

In an effort to find possible beginning and rate of recharge ( in both summer and winter months ) from the environing locality of the boreholes at Morestead Road WWTW site, several secret plans where made of mensural H2O degree ( utilizing in situ force per unit area lumbermans with recordings at 15 proceedingss interval ) as map of averaged day of the month and clip, for the same period. For these survey, informations from 12 borehole drilled through the Chalk at Morestead Road WWTW site where considered and the treatment of ascertained findings is to be presented in Chapter five.

Borehole MWE02

An mean temperature of about 15.560C was measured. It can be seen ( Figure 4.2 ) that the H2O degree deepness is between 36.448 to 43.036 mAOD. It is at a lower limit during winter months ( November to December ) than in summer where a extremum of 43.036 mAOD is observed for Early August.

Figure 4.2: Water deepness fluctuation – Time secret plan for borehole MWE02

Borehole MWE05

An mean temperature of about 10.830C was measured. It can be seen ( Figure 4.3 ) that the H2O degree deepness is between 38.617 to 43.532 mAOD. It is at a lower limit during winter months ( November to December ) than in summer where a extremum of 41.835 mAOD can be observed for Early August.

Figure 4:3: Water deepness fluctuation – Time secret plan for borehole MWE05

Borehole MWE06

An mean temperature of about 10.680C was measured. Water depth scopes between 39.574 to 47.888 mAOD. An about equally distributed H2O deepness fluctuation can be seen ( Figure 4.4 ) from the secret plan.

Figure 4.4: Water Depth Variation – Time secret plan for Borehole MWE06

Borehole MWE07

An mean temperature of about 10.870C was measured. Water depth scopes between 33.132 to 35.179 mAOD. Besides, an about equally distributed H2O deepness fluctuation can be seen ( Figure 4.5 ) but non every bit defined as with MWE06, from the secret plan. A zag zig agreement is easy identified.

Figure 4.5: Water Depth Variation – Time secret plan for Borehole MWE07

Borehole MWE08

An mean temperature of about 11.270C was measured. Water depth scopes between 33.571 to 36.863 mAOD. Water depth fluctuation is at a lower limit during winter months ( November to December ) than in summer and fall with a extremum of 36.863 mAOD observed in Early August ( Figure 4.6 ) .

Figure 4.6: Water Depth Variation – Time secret plan for Borehole MWE08

Borehole MWE09

An mean temperature of about 12.900C was measured. Water depth scopes between 34.588 to 38.842 mAOD. Water depth fluctuation is at a lower limit during winter months ( November to December ) than in summer and fall with a extremum of 38.842 mAOD observed in Early August ( Figure 4.7 ) . The secret plan is similar to MWE08.

Figure 4.7: Water Depth Variation – Time secret plan for Borehole MWE09

Borehole MWE13

An mean temperature of about 12.900C was measured. Water depth scopes between 37.721 to 43.122 mAOD. Water depth fluctuation is at a lower limit during winter months ( November to December ) than in summer and fall with a extremum of 43.122 mAOD observed in Early August ( Figure 4.8 ) . From September to October the fluctuation is comparatively changeless before a steep diminution occurs until the terminal of November and early December.

Figure 4.8: Water Depth Variation – Time secret plan for Borehole MWE13

Borehole MWE14

An mean temperature of about 11.500C was measured. Water depth scopes between 38.380 to 43.979 mAOD. Water depth fluctuation is at a lower limit during winter months ( November to December ) than in summer and fall with a extremum of 43.979 mAOD observed in Early August ( Figure 4.9 ) . From September to October the fluctuation is comparatively changeless before a steep diminution occurs until the terminal of November, where few extremums and falls are observed before another diminution to lowest in December.

Figure 4.9: Water Depth Variation – Time secret plan for Borehole MWE14

Borehole MWE15

An mean temperature of about 8.290C was measured. Water depth scopes between 37.679 to 39.512 mAOD. Water degree experiences a diminution from July to Early August before a crisp addition is observed to a peak value of 39.512 mAOD. Thereafter, a steep diminution is occurs to early September before a steady and changeless value of 37.922 mAOD stretches the full distribution to December ( Figure 4.10 ) .

Figure 4.10: Water Depth Variation – Time secret plan for Borehole MWE15

4.3.1 CORRELATION BETWEEN VARIATIONS – Time GRAPH

Using the mean H2O degree values per twenty-four hours, four secret plan where made to compare H2O degree fluctuations within these borehole dug through the Chalk of Morestead Road site.

Between MWE02 and MWE05

Superimposing MWE05 secret plan on MWE02, an about similar distribution in H2O degree discrepancy is observed. However, between October and November a distinct difference is observed ( Figure 4.11 ) .

Figure 4.11: Discrepancy in Depth against Time correlativity between MWE02 and MWE05

Between MWE06 and MWE07

Superimposing MWE07 secret plan on MWE06, a similar distribution in H2O degree discrepancy is observed ( Figure 4.12 ) .

Figure 4.12: Discrepancy in Depth against Time correlativity between MWE06 and MWE07

Between MWE08 and MWE09

A overlying secret plan correlating H2O degree fluctuation in borehole MWE08 and MWE09 show an about similar distribution between the measured informations ( Figure 4.13 ) .

Figure 4.13: Discrepancy in Depth against Time correlativity between MWE08 and MWE09

Between MWE13 and MWE14

A overlying secret plan correlating H2O degree fluctuation in borehole MWE13 and MWE14 show an initial fluctuation, with a downward extremum for borehole MWE14 in mid-August, before a close similar distribution can be observed from the measured informations ( Figure 4.14 ) .

Figure 4.14: Discrepancy in Depth against Time correlativity between MWE13 and MWE14

4.4 EFFLUENT DICHARGE CONCENTRATION WITH DEPTH

Chemical analysis was conducted on porewater samples gotten from nucleus logs of the Chalk at Morestead Road WWTW site boreholes, as a map of their several deepness, for the appraisal of both major, hint and determiners concentration. Five secret plans of concentration fluctuation against deepness are made for boreholes MWE02, MWE07, MWE09, MWE13 and MWE15. The major elements analysed are Ammonia, Carbon ( in Total Organic Carbon ) , Chloride, Nitrate and Nitrite. These secret plans are presented in Figure 4.15, 4.16, 4.17, 4.18 and 4.19, severally. Chapter five discusses the plausible beginning, consequence and possible consequence over the long tally of these concentrations to groundwater in the Chalk of the survey country.

Figure 4.15: Effluent discharge concentration – Depth secret plan for Borehole MWE02

Figure 4.16: Effluent discharge concentration – Depth secret plan for Borehole MWE07

Figure 4.17: Effluent discharge concentration – Depth secret plan for Borehole MWE09

Figure 4.18: Effluent discharge concentration – Depth secret plan for Borehole MWE13

Figure 4.19: Effluent discharge concentration – Depth secret plan for Borehole MWE15

Chapter FIVE: Consequence DISCUSSION