Where there is no training - pollution-riskassessment by field-staffby Guy Howard and Alice Simonds

People are waking up to the fact that pollution,and the risk of pollution, must be assessed andmonitored. Hard-pressed, untrained fieldworkerscan contribute - with a little help.

Table 1. Principal characteristics of pollution

Activity Category Main types Impact on suitabilityof poll/utant as source for drinking-

water supplies

UrbanizationUnsewered discharge of sewage poD pno xxxxStream discharge of sewage Pol pno xxSewage oxidation lagoons P opn xxSewer leakage pol opn xLandfill, solid-waste disposal P osnh xWell-head contamination P pn xxx

Industrial developmentProcess water/effluent lagoons P ohs xxTank and pipeline leakage P oh xxAccidental spillages P oh xxxStream discharge of effluent pol ohs xLandfill residue & waste P ohs xxWell disposal of effluent P ohs xx

Agricultural developmentCultivation with:Agrochemicals D no xxxIrrigation D sno xxxWastewater irrigation D nosp xxLivestock rearing/crop processing:Unlined effluent lagoons P pno xStream discharge of effluent pol onp x

Mining developmentMine-drainage discharge pol sha xxProcess water/sludge lagoons P hsa xxSolid mine tailings P hsa xx

Category Types of pollutantP Point p Faecal pathogens h Heavy metals x to xxxx Increasing

impactD Diffuse n Nutrients s SalinityL Line o Organic micropollutants a Acidification

WATERLINES VOL. 14 NO.1 JULY 1995

IT IS BECOMING increasingly impor-tant that water-resource and water-sup-ply agencies in developing countriescarry out pollution risk assessment(PRA) and pollution-monitoring activi-ties. It is rare, however, to find enough,adequately qualified, staff to do this.What commonly happens is that field-workers with other responsibilities areasked to perform monitoring functionsin addition to their existing duties, forwhich they receive limited, if any,additional training.Some field-staff already critically

appraise the environment surroundingwater supplies in order to assess thesanitary risk to the water supply fromlocal activities. The protocols andforms designed to facilitate these arewidely available in a number of texts,for example, WHO's Guidelines forDrinking- Water Quality, Volume 3.\

A new priorityPollution risk assessment methodolo-gies and forms designed with the field-worker in mind are not widely avail-able, however, principally because thisis a new priority in much of the South.Pollution risk assessment is furthercomplicated by the wide-rangingnature of pollution, and the enormousarray of potential pollutants. Unlikesanitary risks, it may not be easy toidentify sources of other contamina-tion; it is often difficult to detect chem-ical pollutants; and field-staff oftenfind it hard to assess the likely risks.In a recent training event for Zim-

babwe's Department of Water Devel-opment, the authors worked with field-staff to produce a pollution risk assess-ment protocol which can be used toprovide basic information about therisk to water supplies or sources frompollution. This protocol is not designedto provide a comprehensive risk assess-ment, but rather to provide a prelimi-nary indication of whether any signifi-cant pollution risk exists.The pollution risk to water sources

from any human activity is a combina-tion of both the pollutant 'load' (quan-

8

tity and concentration of pollutant),and the water source's degree of vul-nerability to the pollution.Many different activities cause pollu-

tion; Table 1 summarizes some keyactivities which have the potential topollute groundwater, and shows theirinfluence on the suitability of a sourceto be used as a drinking-water supply.The actual pollutant load affecting awater source will be site-specific, andwould need to be calculated for anywater source at risk.Water vulnerability is a measure

of how accessible the water source is to

polluting activities. In some cases, thisis simple to assess: for example, if achemical factory has a effluent-pipedischarging directly into a surfacewater source, it is obvious that thewater source will be susceptible to anypollutants released. Estimating the vul-nerability of a groundwater source maynot be so easy.The risk of groundwater contamina-

tion (aquifer vulnerability) depends onthe porosity, permeability, and thick-ness of the overlying soil and rock (thehydraulic accessibility), and the quan-tity and concentration of the pollutant(pollution load). Where aquifers aredeep and overlain with impermeablelayers, the hydraulic accessibility ofthe aquifer is low and, therefore, therisk of even high pollution loads reach-ing the groundwater may be relativelylow. Aquifers which are at shallow

Surface water sources can be particularly vulnerable to pollution.

depth, with a thin unsaturated zoneoverlying them, are much more vulner-able. The same pollutant load will posea different risk, depending on the vul-nerability of the source.Most fieldworkers will not have

access to the information necessary toallow an accurate assessment of aquifervulnerability and, in any case, they arevery unlikely to be trained to interpretthis data. They can collect basic infor-mation, however, concerning the depthof boreholes, and the depth of outflowof a polluting activity. If this informa-tion indicates that the source is likelyto be vulnerable, a detailed assessmentshould be made by either a hydrologistor a hydrogeologist.

Preliminary integratedpollution-risk assessmentsThe primary aim of these assessmentsis to provide information which canprovide guidance when a more special-ized, comprehensive assessment isundertaken. For example, in an areawith industrial discharges, a prelimi-nary assessment would aim to identifythe type of industry, and attempt toobtain some information about thechemicals used or produced, and thewaste disposal/treatment facilities. Atthe same time, a sample shouldbe taken and sent to a suitable labora-tory for a full analysis of relevant para-meters, and some basic parametersmeasured in the field.The results of the on-site testing and

the completed pollution risk assess-ment form can then be sent to the pol-lution-control agency. This informationallows pollution-control staff to decidewhether a follow-up visit and moredetailed investigation into the site iswarranted.The information gathered during pre-

liminary pollution-risk assessmentsrequires some level of informed judge-ment as to what constitutes a signifi-cant pollution risk. It may be difficultfor staff to be able to identify differ-ences between low, medium, and highrisks. In this situation, it is imperativethat field staff are provided with someguidance notes by specialist pollution-control staff. The authors are currentlyworking with Zimbabwe's Departmentof Water Development (DWD) todevelop guidance notes to accompanypollution-risk assessment forms.The DWD staff who recently

attended a training course found manyaspects of risk assessment easy, but haddifficulty in assigning relative scores todifferent activities. For example, indus-trial pollution tended to be judged agreater risk than intensive agriculture,

or the runoff from urban storm drainsor leaking fuel-stores.In many cases, this may be justified,

as controls on industry are not alwaysenforced strictly. It is apparent, how-ever, that in Zimbabwe - in commonwith many other developing countries- industrial pollution is by no meansalways the greatest threat to waterquality, and there are many other pol-luting activities which affect develop-ing countries. These include nitratebuild-up in groundwaters from agro-chemical use.

Desk studyIn order to make an accurate assess-ment of the risk for a water body, theassessor must have access to a reason-able amount of information concerningboth the activities undertaken in thevicinity of that water body, and infor-mation concerning the water bodyitself. The most effective role a field-worker can play is to provide informa-tion on the likely pollutant load, and toidentify broadly the groups of pollutantwhich will be discharged. Field-staffshould also be able to make visualassessments of surface waters.The forms shown in Figures 1 and 2summarize the information requiredbefore a preliminary pollution-riskassessment for a borehole supply canbe undertaken. To collect this informa-tion, a structured approach is essential,to ensure that it is done with the great-est efficiency and accuracy.The first step is to make a desk study

of the water source and its surround-ings so that the assessor has as muchinformation as possible about thesource, in particular the potential vul-nerability and the likely sources of pol-

lution in the area, prior to making thefield assessment. This should includechecks on: available water-quality data;water-intake construction details; localindustries' discharge consents or limits,and their records of compliance; thelocation of pollution sources relative tothe water source; and whether there arepoint or diffuse sources of pollution.

Field assessmentOnce this information has been col-lected and summarized in the form of abrief description highlighting keypoints about the source, such as water-table depth, screen length, aquifer type(if known), and the location of the pol-luting activities identified, a fieldassessment can be made.The first stage of the field assess-ment is a visit to the water source;assessors should make sure there areno problems in the immediate areawhich may contribute to pollution ofthe water. For borehole supplies, thiswill mean checking well-head con-struction, and assessing whether sur-face water can enter the borehole eas-ily. For surface-water sources, this willmean checking whether any activitiesundertaken at the source, such aspumping, or waste discharged from thewater-treatment plant, can pollute thesource.Once the results have been recorded,

assessors should visit all the potentialsources of pollution in the area. Atindustrial sites, this will include a visitto the plant to meet key staff, to assesswhat treatment facilities exist, and toestablish what pollution-preventionsystems are in place. Discharge pointsshould be visited, basic on-site testscarried out if possible and, preferably, a

WATFRT.TNFS VOL 14 NO 1 nJTY 1QQ'i Q

Pollution-assessment form for individual waste-producing activitiesLocal water source reference:....... Source type gw/swPollution Control Officer........... Province .I.Site .2.Activity: Agricultural/IndustriaVUrban/MininglLivestock/Fish farm/Other

6.Waste composition/agricultural applicationmetals YIN Type: .solvents, detergents YIN Type: .waste oils/fuels YIN Type: .inorganic complex YIN Type: .pesticide/herbicide YIN Type: .chemical fertilizer YIN Type: .animal/human waste YIN Type: .

3.Waste-producing activities within site

1.2.3.4.5.

4.Is there on-site disposal?Is there leakage from lagoon/waste-heap?

5.Is there effluent discharge to a river?how far away is that discharge point?does the effluent pipe leak?

Type of potential contaminationsourcePoint Diffuse

YINYIN

YIN......kmYIN

that places such as fuel stations haveprotected fuel storage, and that theyhave acceptable procedures for dispos-ing of waste oils and fuel.Once the polluting activities in the

area have been investigated, they canbe related back to the water source.The information derived from theassessment of pollution risk from indi-vidual activities - and summarized onthe pollution-assessment form (Figure1) is transferred over to the risk-assessment form (Figure 2). It is com-bined with the desk study findings toprovide a preliminary overview of thepollution risk to the water source.If it can be shown that there is likely

to be a large pollutant load, and thatthere are concerns about the vulnerabil-ity of the water source to pollution,then specialist staff can undertake amore detailed pollution assessment.This will include full chemical, biolog-ical, and microbiological analyses, andfull investigations into the hydrologyand hydrogeology of the area to assesswater-body vulnerability, and to predictpollutant movement.

9.Estimated risk of groundwater pollution LOW/MEDIUM/HIGHIf discharge point is within 30km upstream of asurface water abstraction point, what is the estimated risk of contamination to thesurface water supply? LOW/MEDIUM/HIGH

much they use, and how often, andwhen they apply them.Where livestock are reared, details

should be sought as to how wastes andcarcasses are disposed of. Fuel-storesshould also be checked to see if theymeet minimum safety standards, andwaste-fuel disposal methods should beascertained. In urban areas, the asses-sors need to carry out investigationsinto storm drainage and solid-wastedisposal facilities; and they must ensure

ApplicationEssentially, there are two situationswhere field-staff should be expected tocarry out a preliminary pollution-riskassessment. The first is when a newwater source is to be developed fordrinking-water supply, whether agroundwater or a surface water source.The second is where a new waste-pro-ducing activity is initiated in an areawhere there is a water source supplyinga domestic water supply.

Commissioning a newboreholeIt is no longer appropriate to assumethat groundwater from a newly drilledborehole will be of drinking-waterquality without further treatment. Anassessment of the potential for ground-water pollution is, therefore, integral tothe siting of new boreholes. Thisshould include as a minimum the pro-cedure described above, but in a largedrilling programme in which manyboreholes are to be sunk, a moredetailed assessment should be made.The pollution-risk assessment should

be complemented by a full analysis ofwater quality to cover all likely chemi-cal and microbiological constituents.Where possible, some basic parametersshould be analysed on-site during apreliminary risk assessment, to high-light any immediate problems.Surface-water sources are often vul-

nerable to pollution, as many industries

years?

......hectares

......hectares

...... m3

......m3

......years

YIN

YINin the last five

high(>60%)

7.Does the site have discharge limits/consent?8.What is the record of compliance

low(O-20%) medium(2l-60%)

Detailed information:I. No.of years of site activity2. No.of effluent-discharge points3a.No.of hectares of on-site disposal3b.No.of hectares under cultivation4a.Volume of waste produced annually4b.Volumeof chemical fertilizer/pesticide applied annually5. Does site undertake quality control activities?eg:regular in-house monitoring and surveillance

6. Do emergency procedures exist?eg: in case of accidental spillage YIN

7. Which are the appropriate quality standards for this type of activity?8. What pollution control measures have been taken?eg: relocation of underground storage tanks above ground, with appropriatecontainment walls/bunds.

Figure 1. Pollution-assessment form.sample taken for analysis. Assessorsshould always carry a copy of the rele-vant effluent standards, to make com-parisons with anyon-site tests, and toensure that polluters are aware ofcurrent standards.In agricultural areas, assessors

should note the main farming activities- arable or pastoral - and theyshould visit farms close to the watersource. Farmers should be questionedabout the agrochemicals they use, how

10 WATERLINES VOL. 14 NO.1 JULY 1995

4.Estimate of containment load from individual waste-producing activities(see Pollution-Assessment Form)Total no. of High Risk estimates .Total no. of Medium Risk estimates .Total no. of Low Risk estimates .

Number ofdiffuse sources

ies. The forms shown here can bereproduced to make a reasonableassessment of pollutant load. Com-bined with the information gathered onthe water source, this should enablefield workers to make a reasonable riskassessment for water pollution.The forms are still in their infancy,

however, and require further refine-ment. The approach to pollution moni-toring requires further development inmany countries over the next fewyears, as it becomes an increasingpriority. Waste-producing activities arelikely to increase, as will demands onwater resources.It will be many years before there are

groups of well-trained, specialist pollu-tion-control field-staff in developingcountries like Zimbabwe and, untilthen, existing field workers from water-supply and water-resource agencieswill take on the extra work. These staffcan provide the information only ifthey are given sufficient support andtraining.

ReferencesI.Guidelines for Drinking- Water Quality, Volume3: Drinking- Water Quality Control i/l Small-Community Supplies, WHO, Geneva, 1986.

Guy Howard and Alice Simonds both work in theRobens Institute's Environment Division at theUniversity of Surrey, Guildford. Surrey, UK. GuyHoward is Head of Overseas Projects; AliceSimonds is a Research Officer. Fax:+44 1483503517. E-mail:rbslah@surrey.ac.uk

IndustrialAgriculturalMiningUrbanOther

Overall containment load estimate HIGHlMEDIUMlLOW5.Aquifer vulnerability, estimated fromdepth of water-tabledegree of rock fissuringdegree of confinementlithology of unsaturated zonesoil zone (clay rich - sand rich) HIGHIMEDIUM/LOW6.Risk of groundwater pollution is proportional to the aquifervulnerability and the containment load, therefore, risk ofgroundwater pollution is: HIGHlMEDIUMlLOW

Risk-assessment form for a borehole supplyI.Water supply reference no .2.Total number of waste-producing activities within a lOkm radius .3.Breakdown of local activities:

Number ofpoint sources

Figure 2. Risk-assessment form.

or years, as a means of monitoring therisk to water resources.This process should be supportedwith regular sampling from effluentdischarges and water sources in thevicinity - both those in unaffectedareas (baseline stations) and those inaffected areas (impact stations).

Future developmentsBy using a structured PIPRA, fieldstaff can make initial investigations oflikely pollution inflow into water bod-

Training field-staff in pollution risk assessment and on-site testing.

discharge directly into rivers andstreams. This has significant implica-tions for countries like Zimbabwe,where surface-water sources are usedin a great many water supplies of allsizes.

New surface-water sourcesWhen a new surface-water source isbeing developed, it is important that avery thorough risk assessment andwater-quality analysis is undertaken. Apreliminary risk assessment is stillappropriate, however, as this will helpto focus a more detailed assessment onidentified likely problem areas. Whensurface-water sources are being devel-oped, the range of the assessment maybe much larger than for a groundwatersource, because of the rapidity of sur-face-water flow. An assessment oflikely pollutant sources, therefore, maystretch for many kilometres upstreamof a surface water intake.When an activity is established in an

area where there are drinking-watersources, a pollution risk assessmentwill be required. Ideally, a full, inde-pendent environmental impact assess-ment (EIA) will be undertaken, and theresults of this made available to thepollution-control and water-supplyagencies. Very often, however, this isnot the case, and the pollution-controlbody only finds out about a new activ-ity after a pollution event.Where an EIA has not been under-

taken, field-based staff can carry out apreliminary pollution-risk assessmentto evaluate the risk to local watersources. Indeed, in some circum-stances, a number of assessments maybe made over a period of a few months

WATERLINES VOL. 14 NO.1 JULY 1995 11