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10 Water impacts
10.1 INTRODUCTION
We have discussed in some detail a wide range of types of impacts, reducing them to relatively simple logical processes with a potential for automation as expert systems. Although not all the standard areas of impact assess-ment have been covered, there has been enough variety to illustrate most of the problems and issues involved when “translating” expert behaviour and judgement into a simple logical process that a non-expert can follow. This can be illustrated by discussing one last area of impact that encom-passes most of the issues raised in other areas: water, which really consists of a succession of several impact assessments. Water impact assessment is probably the most difficult, because of the extreme variety of impacts that can affect water, and because of the extreme variety of standards and legislation covering them (see Bourdillon, 1995 for an early list). It can be said that Environmental Impact Assessment is a by-product of the relative cultural sophistication normally associated in a society with a certain degree of development, but concerns with the quality and quantity of water have been central to all societies throughout history, and this makes it probably the most extensively documented – and regulated – area of impact assessment. Also, in terms of the line of argument we are following here, water impact assessment involves really a chain of several areas of impact, each of which can be looked at as we have been doing in previous chapters. These areas can be seen as “modules” which form part of water impact assessment, linking the original source of impacts – the project – to the ultimate impacts on humans or on the natural environment (Figure 10.1).
• The project can produce certain effects directly on a water system (discharges to it, abstractions from it) and it can also have certain effects on the groundwater.
• The behaviour of the groundwater will determine possible indirect effects on water systems, as well as other effects on the soils and on the usage
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Figure 10.1 The interlinked logic of hydrogeology, water, and water-ecology impacts.
of water as a resource; in impact assessment, these impacts are usually covered under headings like “hydrogeology and soils”.
• Be it directly or indirectly, the water system is affected in terms of “water quality/quantity”: volume, flow and possible contamination.
• In turn, the water system affected has effects (impacts) on the usage of water as a resource (for drinking, leisure, etc.) and on the ecology of its environment.
• Usually, water ecology impacts are studied under one of two headings: “freshwater ecology” (rivers and lakes) and “coastal ecology” – with a third category of “estuarine ecology” used sometimes – depending on the type of water system.
We can treat the study of water impacts as a sequence of impact studies, from hydrogeology to water quality to ecology. As already mentioned, the literature on each of these areas is vast, and impact assessment manuals can be good summaries of the field (like the very detailed account in York and Speakman, 1980) and can also provide good “guides” to the literature (Westman, 1985; Petts and Eduljee, 1994a and 1994b; Atkinson, 1999; Biggs etal., 2001; Hodson etal., 2001; Morris etal., 2001d; Thompson and Lee, 2001). It is also an area with much legislation and regulation, the latest of which being the EC’s Water Framework Directive (EU,
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Water impacts 319
2002).46 Here, we are going to follow the same logic as before, discussing each of the main steps in the flow chart above, and treating in greater depth each of the specific areas of impact study.
10.2 THE PROJECT
Since we are looking for both “direct” effects and “indirect” effects (through hydrogeology) on all the water systems around the project (surface or underground), we are interested in those aspects of the construction or operation of the project likely to generate such effects. For the construction stage, the list concentrates on the type of project it is and its features on the one hand, and on construction practices on the other (for reasons that will become clear later, we are marking with an asterix * those aspects with a link to hydrogeology):
1 The type of project and the presence/absence of certain features may involve:
• tunnelling or mining (*);
• quarrying or deep excavations involving soil removal (*); • site-levelling involving earth movements (*);
• foundations involving piling (*);
• temporary modification or manipulation of water systems, changes in the course of a river, erection of water-protection barriers;
• construction of drainage systems (*).
2 Concerning on-site working practices:
• number of workers;
• phasing of construction;
• materials used for construction;
• policy concerning the control of dust and particulates by vehicle and earth movements;
• vehicle movements, and the type of fuel to be used (especially diesel);
• on-site policies about storage of fuel and oil tanks and dealing with losses and leakages (*);
• policy about disposal of empty fuel and oil tanks (*).
46 Also available as a consultation document circulated by the UK’s Environment Agency on the internet in page http://www.environment-agency.gov.uk/yourenv/consultations/305276/ ?versione1&lang=_e or by e-mail from waterframeworkdirective@environment-agency. gov.uk.
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320 Building expert systems for IA
During the operation stage of the project, the presence of any features which could alter or contaminate the water systems may include (* indicates a link to hydrogeology):
1 project areas: area affected, area paved (*);
2 number of persons using the site: workers, customers/visitors, suppliers; 3 what facilities are included in the project: canteens, toilets, water-
related facilities like swimming pools;
4 concerning the discharge of foul water from the project: connected to existing sewers, a new sewer (*);
5 storage tanks (*):
(a) their contents,
(b) their location: above ground, below ground;
6 pipelines and their location (*): above ground, below ground;
7 other discharges apart from foul water from toilets and kitchens:
(a) composition of the discharges: materials, chemical composition, flow rate, temperature,
(b) concentration: from a point source, diffuse, (c) location of the discharges:
(i) to a water system, are there balancing facilities (like a pond) before the release outside? (*),
(ii) to the ground (*): as run-off water, to soak-aways.
8 water abstractions:
(a) from a surface water system,
(b) from bore-holes from underground aquifers (*), (c) flow/volume required.
This list is really a combination of the individual lists we would require if we were studying hydrogeology, soils or ecology, which overlap considerably with each other. How to proceed next is dictated by the project features present. In the first place, the list of project features can show that the project will discharge to (or abstract from) a surface water system directly (and we can study these impacts on the water), or that it will discharge to the ground or affect the ground in other ways (earth-movements, etc.). If the latter is the case, these ground-related actions can produce two kinds of impacts to be studied separately: (i) impacts on the soil itself, which we would study as a separate area of impact assessment; (ii) impacts on the hydrogeology beneath it, which we also study as another area of impact assessment, and finally, the hydrogeological effects in turn are likely to impact on the surface water system (Figure 10.2).
This discussion does not cover Soil impact assessment, because the focus is on direct or indirect impacts on water. Soil impacts merit a whole section
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Figure 10.2 The chain of project effects on soil, hydrogeology and water.
of their own (they usually do in manuals and in Environmental Statements) involving baseline studies, impact identification, standards, mitigation, etc. Good-practice guidance on soil impact assessment can be found in Petts and Eduljee (1994a), Hodson (1995) and Hodson etal. (2001), which also contain references to government guidance and standards.
The focus of our hypothetical study of impacts here depends on what features are present in the project and whether they are likely to produce direct or indirect impacts on water: (i) if the project has features that suggest there are likely to be hydrogeological issues involved (indicated by the presence of project features marked *), we proceed to the study of hydrogeological issues; (ii) if the hydrological effects from the project are only direct ones to a surface water system, we can move on directly to study water quantity and quality in those systems (Section 10.4 below).
10.3 HYDROGEOLOGY: THE BASELINE
Hydrogeology – often studied together with “soil” – is another typical area of impact assessment, and it follows a logic similar to the others, from the baseline study to the determination and mitigation of impacts (Figure 10.3). The baseline study develops from a map-based desk study into an exercise in consultation with organisations that have the relevant information (Simonson, 1994),47 and only rarely – for big projects with a big budget for the impact study – does it involve fieldwork to collect information. As this process evolves, the area of study also changes,
47 The knowledge acquisition for this part was greatly helped by conversations with John Simonson, of Environmental Resources Management Ltd (Oxford branch); Mathew Anderson helped with the compilation and structuring of the material for this part. However, only the author should be held responsible for any inaccuracies or misrepresentations of views.
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