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lS 13969:1994 tTrcfrq qFTS' qTqlqo qTqt d qqi Ai * qrfqqit fluaro nn Indian Standard SAMFLING OF GROUNDWATERS - GUtrDELINES UDC 628 ll2:543'3 o Brs 1994 BUREAU OF INDIAN STANDAR.DS MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MAR.G NEW DELHI I IOOO2 Price GrouP 4 Iuly 1994

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lS 13969:1994

tTrcfrq qFTS'

qTqlqo qTqt d qqi Ai * qrfqqit fluaronn

Indian Standard

SAMFLING OF GROUNDWATERS -GUtrDELINES

UDC 628 ll2:543'3

o Brs 1994

BUREAU OF INDIAN STANDAR.DSMANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MAR.G

NEW DELHI I IOOO2

Price GrouP 4Iuly 1994

Ground Water and Preliminary Investigation Sectional Committee, RVD 3

FOREWORD

This Indian Standard was adopted by the Bureau of Indian Standards, after the draft finali:"gd !Vthe Ground Water and Preiiminaiy Investigation Sectional Committee had been approved by theRiver Valley Division Council.

This standard deals with the sampling of groundwaters, the techniques to be used and the handlingof water samples obtained from groundwaier sources.

The general purpose of sampling programmes commonly devised for gror,rndwaters is to surveythe quality of groundwater iupp-lies, Io detect and asseis groundwater pollution and to assist ingroundwater resource management.

In the preparation of this standard considerable assistance has been derived from ISO 5667(Part ll ): 1993'Waterquality- Sampling: Part ll Guidance on sampling of groundwaters''

For the purpose of deciding whether a particular requirement of this standard is complied with, the-final value, bbserved or caliulated, expiessing the reiult of a test or analysis, shall be rounded offin accordance with IS 2: 1960'Rules'for rorinding offnumerical values (revised\'. The number ofsignificant places retained in the rounded off valu--e should be the same as that of the specified valuein this standard.

IS 13969 | 1994

Indian Standard

SAMPLING OF GROUNDWATERSGUIDELINES

I SCOPE

1.1 This standard presents guidance on thedesign of sampling programmes, sampling techni-ques and the handling of water samples derivedfrom groundwater for physical, chemical andmicrobiological assessment.

1.2 This gtandard does not cover sampling relatedto the day-to'day operational control of ground-water abstractions for potable or other purposes,but is concerned with the general qualitysurveillance of groundwaters. Because of thecomplexity of groundwater sy$tems, many specificsampling applications will require specialisthydrogeological advice which cannot be detailedin this standard.

2 REFERENCES

The following standards are necessary adjuncts tothe standard:

15 No.3025 (Partl): Methods

1986 ( physicalwater andSampling

Titleof sampling and testand chemical ) forwaste water: Part I

4410 (Part I l/ Glossary of terms relating toSec 6 ) : 1985 river valley projects : Part I I

HydrologY, Section 8 Ground-water

3 TERMINOLOGY

3.1 For the purpose of this standard thedefinitions given in lS 4410 (Part 1l/Sec 6) :

1985 shall apply.

4 SAMPLING EQUIPMENT

4.1 Materials

General information on the choice of materialsfor sampling and bottles is given in IS 3025( Part I ) : 1986. Polyethylene, polvoropoolvcarbonate and s6ss-cdGinAs are recom-in6ndill6r most ;ambtin-g-sriuaTi6ni.

..'_:

If the biological quality of groundwater is likelyto cause changes in the physico-chemical composi-tion of the water, as much light as possible shouldbe excluded by using opaque sample containers.

When sampling groundwater for organic consti-tuents, contamination of the sample by otherorganic material used in the construction of theborehole or present in the sampling equipmentneeds to be minimised. This is especially importantwhero trace levels of organic constituents are of

interest, it is advisable to use special equipmentmanufactured from glass, stainless steel, orother material incapable of leaching organicconstituents.

4.1.1 Malerials for Borehole Construction

Suitable materials for monitoring borehole casingand screen are required to avoid modification tothe chemistry of groundwater samplcs. Threadedjoints on well casing are recommended so thatglues and cements do not introduce additionalrisk of sample modification. A wide variety ofmaterials are available for use in borehole con'struction. In view of their low cost, widespreadavailability and easy handling, the commonthermopiastics ( notably rigid PVC ) are recom-mended for most groundwater sampling purpose$.However, groundwater that is highly contaminat-ed with synth€ti6-organic solvents will attack anddeteriorate PVC well casing and screen. In suchcircumstances stainless steel or polytetrafluor-ethylene are the materials recommended forborehole construction because of their resistant,inert character.

4.2 Types of Equipment

4.2.1 Pumps

A wide variety of pumps, many of which areportable, are suitable for groundwater application.They differ greatly in their design and pumpingcapacity and are suited to different conditions ofborehole construction and sampling depth.Suction lift pumps installed at the surface cannotlift water from more than 6 m and submersibleelectric pumps are therefore recommended formost groundwater sampling. Suction lift pumpsshould not be employed in those situations wheresampling is carried out to examine primarily thedissolved gaseous content of groundwaters.

4.2.2 D?pth Sampling Equipment

Depth sampling equipment ( often known as'thref' or'grab' sarnplers ) are devices that can belowered into a borehole to collect a sample at aspecific depth. Designs differ mainly in theirclosing meihanism. Open tube samplers allowthroughflow of water and can bc sealed at aspecific depth be means of a mechanical messengero1 electrically operated catch. For some specificpurposes, such as sampling an aquifer contami-natad by an immiscible organic compound, asealed depth sampler is preferable. The designused should be such that no water comes into

r

lS 13969 ,1994

contact with thc sainple container until the deviceis activated at the required depth. Where othermethods ol sampling are impractical, such as invery deep aquilers ( i.e. greater than 100 m ),depth sampling is recommend;d.

Samples of water may also be collected in a bailerduring drilling to provide crude data on ground-water quality variation with depth. On otheroccasions, where pumping of a borehole is notpossible, a sirnple bailer such as a weighted bottleor other open container can be lowered into theborehole to collect a water sample. The use of abailer is only recommended for sampiing thesurface layer of the aquifers and is not recom-msnded where other methods are available.

4.2.3 In-situ Sampling Devices

These include devices such as porous cups andpiezometer points that are permanently installedat a specific depth in the aquifer from whichdiscrete samples can be collected, These samplingdevices are often installed at different deptns ina boiehole. Porous ceramic cups rnay be used inthe unsaturated or saturated zones. To extractwater that enters the porous cup, a vacuurn isapplied through a tube attached to tire cup.There are other devices that allorv water to enterthrough a wire mesh into a sample chaorber tirat isevacuated by preisur"ising with cornpressed air.Piezomoters, s:nrll diain:ter tubes screened atthe end and open io the surface, can providegroundwater sarnples frorn small diarneter pumps,or by suction if the water level is close to groundlevel. Several piezometers can be sealed atdifferent depths in a single boretrole. ( Seealso 5.3.1.3 ).

4.2.4 Packer Sysiems

Packer systems provide a means of extr.actingwater from specific depth intervals within aborehole. The system may consist of one or morepackers which can be expanded either hydrauli-cally or pneumatically once in position down theboreirole, to provide a seal. A ivater sample isobtained from the sealed section by pumping orby gas displacement. A variety of systems areavailable, some for permanent installation, theothers portable. Packers are not suitable foruse in boreholes with a gravel pack. ( Seealso 5.3.1.1 ).

4.2.5 Pore Water Sampling Systems

For detailed information about groundwaterquality at different depths in either the unsatu-rated or saturated zone of an aquifer, pore-watersamples can be extracted from rock samplesobtained from purpose drilled boreboles. Thepore-water is extracted by centrifugation. Thissampling technique is expensivo and is notrecommcnded for routine monitoring because itrequires repeated drilling.

5 SAMPLING PROCEDURES

5.1 Sampling Point Selection

5.1.1 General

When using existing boreholes to obtain andgain access to ground lvirter, it is necessary todetermine constructional details to define fromwhich strata the sample is being obtarned. Whennew boreholes are being construcied specificallyfor sampling, the design of the borehole ( forexanrple, the screen size and iength ) and themethod of construction need to be chosen, notonly to meet the sampling requirement, but alsoto minimise contamination or disturbance of theaquifer. The use of d!'grr'asants, lubricants, muds,oils and bentonite during cirilling should beavoided if at all pcssible, particularly whenconsidering sampling for organic compounds.Also care is necess,riy to ellsure that boreholescompleted with a gravel peck around a solidcasing and screens at specific levels are not subjectto short circuiting of aquifer *,ater from differentdepths via the gravel pack. This can be achievedby sealing the gravel packing in the vicinity ofthe screens. Attention should also be given tothe design of borehole insiallations at the groundsurface, in order to prevent contrmination of theborehole by surface lvater.

5.1,2 Groundwater Qualitl, Surveiliance o.f PotableSupplies

lVhen monitoring the quality of groundrvatersupplies for potable or anv other use, all pumpedboreholes, wells and springs should be sampledin order to protect the use to which the water isput. For potable supply purposes, any nationalraw water sampling requirements should bereferred to for more detailed advice.

Wiren selecting sarnpiing poirrts for supplysurveillance, it is recommended that some bore-holes remote from the abstraction are monitored,in order to examine the effect of the abstractionon the dynamic cha:-acteristics of the aquifer( e,g. the natural groundivater flow, the variationin thickness of the saturated zone ).

5.1,3 Other Groundv,ater Quality Purposes

For other sampling purposes, the selection ofoptimal sampli;ig points wili be more difficult andbe directiy inftuenced by the purpose of sampling,in addition to the particular characteristics of theaquifer that is being sampled ( e.g. the nature ofthe ground.water fforv, rvhether intergranular orfissure, the hyCraulic gradient and the directionof flow ). In theEe cases it is essential to seekspecialist hvrlrogeological advice to assist in theselection of the most appropriate samplingpoint(s). Tlie use of existing wells or boreholesshould not be considered unless they can beshown to be suitable for the purpose of thesampling programme. ( In many cases existingwells and boreholes may fully penetrate theaquifer and be open, or screened, throughouttheir depth, thus making it difficult to examinequality at specific depths. )

Nevertheless, some generalised guidaace can begiven when the objective is monitoring ground-water for contamination from diffuse or point-source inputs.

5.1.3.1 Diffuse contamination of groundwater

When designing monitoring networks to identifyextensive diffuse-source pollution of aquifers, theuse of existing sampling points in the form oflarge capacity production boreholes is recom-rnended as they can provide integrated samplesfrom a large volume of the aquifer. However, insome cases of localised or low intensity pollutionthe usc of this type of borehoie may dilute thecontamination to levels below the analyticaldetection limit, in these clses smaller capacitypumped boreholes are recommended. The partof the aquifer most sensitive to pollution is thatllear the boundary between the saturated andunsaturated zones. Sampling boreholes shouldtherelore include at least one with a screen nearto the surface of the saturated zone. Otherpurpose-drilled boreholes should be completedand screened over different depth iniervals of theaquiler. Sampling bcreholes should be locatedthloughout the area of interest. It is recommend-ed that sites are chosen to represent the differenthydrogeological and land-use conCitions andareas considered to be particularly vulnerable todiffuse Pollution.

5.1.3.2 Point-source contaminqtion of groundwater

When specifying sampling points to monitorpoint-source pollution, such as that arising froma waste disposal landfill site, it is necessary toconsider the location of the site of the pollutionin relation to the groundwater flow direction.Where practical, it is recommended that asampling borehole to monitor the quality of thegroundwater directly beneath the pollution sourceis installed. In addition at least one samplingborehole should be screened ovet a narrow depthrange immediately below the water table, so thatanv oollutants less dense than water will be more

"uiily d"t."ted. Further sampling points should

be located at progressive distances down thehydraulic gradient from the source of contami-nation, and provision made for sampling from a

range of depths. Consideration also should begiven to the location of one or two boreholes upthe hydraulic gradient from the source of con-tamination, so that the areal extent of thepollution plume can be identified. Such boreholesmay also be of assistance to quality controlstudies, by providing information on the extent ofpotential contarnination by the sarnpling pro-iedure, particularly where the analysis of tracematerials is of interest.

5.2 Frequency anil Time of Sampling

Analytical results from a sampling programmeneed to provide estimates of the required infor-mation within the tolerable errors defined in the

IS 13969 r 1994

objectives of the sampling programme. If thcobjectives do not include definition of thcmagnitude of the tolerable error, a statisticallybased sampling programme is impossible.

For quality surveillance of potable supplies ( orany other use-related monitoring activity ), thetemporal variation in quality at a single point isthe most important factor. For most determi-nands, monthly or even less frequent samplingwill be adequate when the purpose ol' samplingis to aesess the suitability of groundwater as asource of drinking water. Refer to IS 3025(Part I ): 1986 and any national statutoryrequirements for general guidance on samplingfrequency assessment. More frequent samplingmay be required to minimise any public healthrisks in those situations where groundwaters areused lor potable supplies without disinfection.

For objectives other than potable supply surveil-lance, the sampling frequency should be chosenaccording to the variation in quality of the ground-water under investigation, in both a temporal andspatial sense. Quality changes in groundwaterare usually much more gradual in time and spacethan those in surface waters. [n some aquifersthere are factors producing seasonal variations inquality and in other cases, particularly wheregroundwater pollution is occurring, therc areshort term variations of between several hoursand about two days in the composition of samplesobtained during a pumping cycle. These varia-tions have to be recognized before a long-termprogramme is defined.

Continuous monitoring of pH, tcmperature andelectrical conductivity can provide a useful meansof identifying the need to incrcase or decrease thesampling frequency for determinands that mustbe characterised by sampling. In casc continuousmonitoring indicates the rate of quality changesis increasing, then the sampling frequency shouldbe increased for any determinands of interest;conversely, if the rate of change decreases, orstops, the sampling frequoncy may be reduced.

In those cases where there has been a considerablechange in quality of any continuously monitore ddeterminand, it is advisable to consider alsoextending the range of determinands to beroutinely analysed, as a precaution.

Continuous monitoring is also a useful means ofidentilying the most appropriate time to samplepumped observation boreholes which are beingused to obtain representative samples of' aquiferwater. Where significant variations are recorded( * t0% within the pumped discharge ) thisprobably indicates local transient conditionswithin the borehole itself during the early stagesof pumping and samples should not be collecteduntil the monitoring suggests that an equilibriumhas been reached. lfno significant quality varia-tions occur then the time at which the sample iscollected after the commencement of pumpingneed only be sufficient for tbe borehoie 1o bepurged.

IS 13969 z 1994

5.3 Choice of Sampling Methotl

5.3.1 Factors Affecting Representative Sampling

In order to achieve representative sampling withinan aquifer, thc sampling method needs to becapable of withdrawing samples whose composi-tion reflects the actual spatial and temporal com-position of the groundwater under study. Sincethe majority of sampling points in aquifers arewells or boreholes, they will disturb the naturalgroundwater system and this may be especiallypronounced as a result oI induced verticalchernical and hydraulic gradients.

In soine snmpling situations, rnineral materialmay accumulate in sampling boreholes betweensampling operations resulting in the water rvithinthe borehole column being unrepresentative ofthat in the aquifer under study. Samplingboreholes should therefore be purged beloresampling by pumping to waste a volunre of waterequivalent to at least the internal volume of theborehole itself.

Vertical stratification in groundwater quality maybe natural or a consequence of pollution. Forexample, most diffuse pollution results in a rnorepolluted layer of groundwater at the top of thesaturated aquifer whereas pollutants that aremore densc than water tend to accumulate abovea less permeable layer at depth, or at the base ofthe aquifer. Sampling methods therefore needto be capable ofdetecting vertical as well as arealvariations in gioundwater quality.

The method of sampling also needs to reflect thecomplexities of groundwater flow in that it musttake account of the aquifer flow mechanism( whether fissure or intergranular ), the directionof the flow and the hydraulic gradients in theaquifer, which can produce strong natural flowsup or down the borehole column itself. Tradition-ally, two comncn sampling methods are employ-ed, namely pumped sarnpling and depth sampling;botb have their uses and li,nitations, rvhich needto be carefully considere.l when identifying thescope for their use.

5.3.1.1 Pumped sampling

Pumped samples from production boreholes usedfor pctablo or other supplies m:y comprise amixture of water entering the open or screenedlength of the borehole from different depths. Thissampling rnethod is therefore, only recommendedwhere groundwater quality is vertically unilormor where a composite vertical sarnple of approxi-mately average composition is all that is required,as might be the case when sampling waterabstracted from a borehole for potable supplypurposes. In these cases, depending on the well-head construction, the water sample should becollected as close as possibie to the exit from theborehole, in order to avoid sample instabilityproblems (see 5.4).

Samples should not be collected from pumpingboreholes until the pump has been running for asufficient length of time to remove the standingwater in the borehole column to ensure that newrvater is being drawn directly from the aquifer'The pumping time reqttired can be calculatedapproximately from the size of the borehole, thepuhping rate and the hydraulic conductivity butshould be more accurately determined by moni-toring any changes in pH, temperature orelectrical conductivity of the pulnp:d rvater: inthese cases samples should not be taken untilsuch timo that no significant variations ( i e.

+. l0% ) are observed.

The most effective methods of taking samplesfrorn an aquifer in which grounJrvater qualityvaries with depth are to sample specific aquilerhorizons using specially constructed observationboreholes or, alternatively, to sample from sealedsections of boreholes. In the former, portabiepumping equiprnent can be used to pump samplesirorn a series of observation boreholes in relativelyclose proximity, each completed and screened toenable samples to be drawn from a dlff'erent depthrange of the aquifer. In the latter, samples arepumped from a sealed section of a borehole bymeans of a packer-pump assembly, therebyproviding a means of a discrete sample of wateru'ithin a specific depth range of the aquifer(see 4.2.4 ). Titis sampling method is onlyrecommended lor use in consolidated aquifers,it is not appropriate for use in boreholescompleted with a screen and gravel pack.

5.3.1.2 Depth sampling

Depth sampling consists of lowering a samplingdevice ( see 4.2.2 and 4.2.5 ) into tlie borehole orwell, allowing it to fill with water at a knowndepth, and retrieviog the sample for transfer toan'appropriatecontainer, where necessary. Thismethod of sampling is normally only suitable foruse in observation boreholes that are not beingpumped although depth samples cail be collectediromboreholes during pumping if there is clearaccess past the purnp such as a solid access tubeinstalled for the purpose. Dopth samples shouldnever be collected frorn rvithin the solid casing ofa borehole, since the water caRnot have originatedat the depth at rvhich the samplirrg device isactivated and, under siatic conditions, may havealtereil in quality due to ciremical ormici'obiological act ivity.

Even within the open or screened section ofboreholes, depih samplir.rg can only be of limitedvalue because naiural or induced flows within theborehole can make the origin of the samplesuncertain Depth sampling is only suitable ifthe origins of, the samples ( in terms of the depthsof water inflow into the borehole ) are known.This may be achieved by determining the depthsof water inflow to the borehole and flows rvithinthe borehole column from interpretation ofdownhole logs of temperature, conductivity andflow under pumping and static conditions.

4

\I

\\-here it is necessary to purge boreholes{ see 5.3.1 ) from which depth sampies are to betaken, it is recommended that the borehole ispumped using an air lift device, prior tosampling.

5.3.1.3 Other sompling methods

On occasions when tlre above sampling methodscannot be used or are thought to be inadequate,it rs recommended that samples from drscretepoints in the aquifer sl.rould be obtained by oneof a variety of in'situ sampling devices. Theseinclude porous cups or piezometer pornts fiomuhich water is extracted by vacuum or gas dis-placement. Several instruments can be tnstalledin a single borehole and some of the devices arealso suitable for use in the unsaturated zone.S:nples from particular depths may also beobtained by pore-water sampiing. This invoivesextracting water ( usually by centrifugation ) fromsoii or rock samples obtained by specialise d coredrilling. It provides the most effective rnethodol quantifying vertical variations in quality andis also a very effective method of sampling theunsaturated zone. However, for periodicmonitoring it has the disadvantage of requirri.rgrepeated drilling and is therefore an expensi'remethoci of sarnpling.

5.4 'Iransport, Stabilisation and Storage ofSanrples

Groundr';ater samples are often taken at sitesrearcte lrorn laboratory facilities. The manner in* hich groundwater samples are stored andhandled before analysis is therefore extremelyirnp.rrtant il results are to be representative ofcoidriions at the time of sampling. For generalgi:jdance on these aspects, refer to IS 3025{ Pait i ) : 1986 but account should be taken of::re ioil.l., ing specific guidance.

Tre most si_en ificant problern in ground waters:-n:1r:g is lhat of obtaining an accurate indica-:r-'"u -rf x'ater quality in the sub-surface. Problemsa::s€ because of the physical and chemicalc .::_Ees that occur as satnples are removed fromaq r,ler 'rIost groundwaler sanrpling methodsre:u"i lr lhe sampie undergoing temperature andrr:ess:re changes q'hich can alter such variablesis,"H. el:ct:-ical conductivity, electroclremicalpr-r3:l:i:1, s:-rlphide content and dissolved gas.':r::-i' ( lrrticularly oxygen and carbonc:ir,::e l. In turn these changes may alter thes:e:-ar:cr oi some constituents. Atmosphericc r,n:lcr ma1' br-ing about similar changes andal. r re::1t in oridation. increased microbiological::tr'r r:,, . pr-ecipilation, volatilisatron and changesr:r -xnr3arance ( e,g. colour and ttrrbiCity ). it isir:-r::ai'lr for g;oiindx'aier samples that as manyi:le:nirations as is practicable are carried out,:n-sr-e or as soon as possible after the sample has::e:i c,r.lecteC. This is particuiarly importantin ies::ct of temperature, pH, electrochemicalp ieni:ai. electrical conductivity, alkalinity and

'iissolled gases ( especially oxygen ). A con-tinuous mersurement technique is prefe;able and

IS 13969: 1994

is best carried out using flowthrough cell systemsthat prevent contact betvreen sample andatmosphere.

On-site filtration of samples is recommended fq1stabi lisin g sanr p lrs, pa rt ic ii I arl y wherE specifi qat-ionis under study. A wide range of filtration mediais available and includes cellulose based nrem-brane filters, in addition to glass fibre andpolycarbonate filters. No singie rr,edium can beuniversally recommended, alrhough glass fibrefilters have some advantage over othei nredia ofsimilar pore size ( e g. cellulose filters ) since theyblock less frequently yet provide sin-rilar filtrationefficiency in terms of particle slze retention. Therecomnrended pore size for general purposegroundwater work is 0'4 to 0'5 m, althorighother pore sizes may be preferable, dependingupon the particular sampling purpose and thedeterminand of interest. Whatever meciium isused for filtration, it is recommended that sub-sequent results ( following analysis ) be reportedas 'filterable' species ( quoting the appropriatepore size of the filter ) ratbei than 'dissolved'spe cies. It is particularly important that onsite filtration of anaerobic grour,drvater shouldbe carried out under anaerobic conciitions.

In all cases it should be ensured that sampleconlainers are delivered to the laboratory in atightly sealed condition, protected fr cm thee{lects ol iight and exiessive heat: if this is notdone, sample quality may change rapidly due togas-exchanpe, chemical reactions and themetaholism 6f organisms. Also it should beensured that samples which cannot be analysedwithin a day are stabilised or preserved. Forstorage over short periods, cooling to 4"C maybe anplied; for keeping over longer periods,freezing to - 20"C is advisablc. lf the lattertechnique is used, it is necessary to ensure thatthe sample is completely thawed before use asthe freezing process may have the effect of con-centrating soirie components in the inner part ofthe sample, the part that freezes last.

Samples may also be preserved try the additionof chemicals, but care shotrld be taken that thechosen method of preservation does not interfereu'ith the subsequent laboratory examination.

6 SAFETY PRECAUTIONS

General guidance on safety matters is given inlS 3025 ( Part I ): 1986 but the following safetyaspects should be conside red when samplinggrounriwaters.

The surface area around r.vells and boreholesshould always be regarded with some cautionsince there may be risk of surface coliapse,especially around old wells. Staging and ladderswithin shafts may be unsafe and a proper safetyharness must always be worn when enterirg wells.At least two persons should be present duringany sampling operation: one person should

1

rs 13969 | t994

always rcmain at the gurface in a position tosummon assistance if hazardous conditionsdevelop or there is any risk to the person under-taking the rampling operation in the well.

Where -sampling takes place in a confined place( c.g. within a well, boreh-ole, well head or ^base-

ment ) the atmosphere should be tested on eachoccas,ion for oxygen deficiency and the presenccof,inflammable gases, hydrogen sulphide-or anyother toxic gases and vapours that could bapresent, it may even be necessary to carry outthese procedures in unconfined spaces whenscvere contamination of any area surrounding agroundwater installation is bcing investigated.Suitable protective clothing must always be wornwhen undertaking sampling operations and underno circumstances should any routine samplingactivity continue if safety checks indicate poienti--ally unsafe conditions exist; if samples have tobe withdrawn in this type of situation then specialprocedures will be required which may need tobe agreed with the statutory agency responsiblefor local or national health and safcty matters( e.g. during the use of breathing apparatus, whensampling in confined spaces ).

When dealing with groundwater installationssubject _to heavy contamination, it is importantto carefully examine all relevant infoimationregarding the sources of the contamination, inorder to define the nature of the necessary safetychecks. In those situations where investigationimust take place close to a source of heavy con-tamination, .,operations should take place towindward, if possible, and eating, drinking andsmoking should be strictly prohibited withln thearea of jlvestigation. It may be prudent to carryout mcdical checks on investigaiors immediatclyafter-

_ operational work, ana periodically ui

suitable intervals thereafter.

7 SAMPLE IDENTIFICATION ANDRECORDS

Sample containers should be clearly and unambi-guously marked so that subsequent analyticalre_sults can be properly interpreted. Rll d-etailsrelevant

. to the sample analyiis should be givenon a label attached to the container, wit[ any

other relevant information recorded on a sample1eport.. When rnany sample containers are need-edfbr a single sa.mpling 99caqion, it will be usuallymore convenient to identify the containers usinga single and unique sample ieference number anirecord all relevant sample details on a samplereport. Labels and forms should alwavs 'becompleted at Lhe time of sample collection.

The.details given on aly combination of samplelabel and report will depend on the obiectives'ofthe particular sampling exercise Urit shouldinclude all the necessary information that willcnablc .a repetition of sampling to take placeunder identical conditions. Mat-ters which iouldbe considered for inclusion are:

a) The name and location of the samplingpoint;

b) the date and time of sample collection;c) nature of aquifcr and water bearing strata;d) the typc of sampling point ( e.g. borehole,

well or spring );e) any relevant descriptive information ( e.g.

well dirnensions );f) pumping status and depth of pump suction

and/or discharge;g) water level within the well or borehole;h) method of sample collection;j) depth of sampling;k) sample appearance at time of collection

( e.g. colour, clarity and odour );m) results of on-site analysis ( e.g. pH,

dissolved oxygen );n) dctails of any sample preservation

techniques employed;p) details of any on-site filtration used ( e.g.

filter pore size );q) details of any sample storage method

employed/required;r) the name and designation of the sample

collector.

Annex A to this standard provides an example ofa report that could be used in situations wherethis sampling information is collected.

IS 13969 z 1994

ANNEX A( Clause 7 )

REPORT _ SAMPLING FROM GROUNDWATERS

Nature of sampling point:...

Nature of aquifer:..

Water level within aquifer :..,......

Depth of sampling :.........

Sample appearance :

Details of sample storage method employed/required:.. ..

( Continued )

IS 13969 : 1994

Tcmperatura pH

MEASUREMENT

Conductivity

FIELD

Dissolved Oxygen

IN THE

Eh