Evaluation of the Groundwater Global Pollution Risk:Relationships with Territorial Planning

Problem statement: The protection and enhancing of Groundwater Resour ces (GWR) at an international level have been studied extensively, but they have very rarely been considered in Territorial Planning and Urban Planning. Now more t han in the past, thanks to the technologies and know-how acquired over the years, ignoring responsi bilities with regards to the close link between these themes is no longer possible, therefore a new research field has been introduced that will lead to a strategic approach, in such a way that GWR and ec onomic and urban planning development will be able to co-exist. Approach: This study, through the application of the Holman d Groundwater Global Pollution Risk methods, is an attempt to lin k these two topics. Results: The study was conducted in Aosta, a town in the north-west of Ita ly, in an attempt to assess the effects that a care less management of the setting up of polluting activitie s could have on the aquifers. Conclusion: The analysis was carried out using a Geographical Infor mation System (GIS).


INTRODUCTION
The proposed work deals with a portion of the Aosta Valley, a region in the north-west of Italy, which is over 8 km long and 40 km wide and has a roughly quadrilateral shape (Fig. 1). The Valley borders on France, Switzerland and the Piedmont Region.
The investigated area is within the perimeter of the city of Aosta and it encompasses the Aosta plain and the flat part of land that ends at the Montjovet gorge.
The Table 1 lists the main directives and laws, with reference to the three legislative levels (European Community, National and Regional), for the study area considered.

MATERIALS AND METHODS
The aim of this study was to carry out a qualitative deterioration analysis of the groundwater, through the calculation of pollution risk in relationship to two different situations: • The first, which takes into account the risk generated by a single, Defined Hazard Centre (DHC) (Civita, 1990;Civita et al., 2005) or Diffused Hazard Source (DHS) (Pfannkuch, 1990;Foster and Hirata, 1988) on the territory and its resources; in this case, the Holman method (Holman, 1958) was used to carry out the analysis. This method is used to obtain an immediate decision-making instrument for emergencies and it can be used to set the basis for subsequent, more in-depth analyses which instead use a more territorial type approach • The second, which takes the Groundwater Global Pollution Risk (Civita and De Maio, 1997) into account, that is, the pollution generated by the presence of multiple and different DHC and/or DHS over an extensive territory, in relation to the water resources and, consequently, the population supplied The Holman method consists of an accurate survey of the DHC and DHS in the study area. As far as the involved space, it is concerned to distinguish the punctual DHC (e.g., a seeping tank) from the general ones, or DHS (e.g., a plot of land cultivated with agrochemicals). On the basis of accurate statistics, it is possible to highlight the activities that most frequently cause groundwater pollution and to draw up a potential hazard list.
It is necessary to assess the different Hazard and Control Factors for each DHC, whether natural or man made, which determine or prevent groundwater pollution.
For each of the aforementioned factors, a weight has been set in a 1-3 range (1 = low hazard; 2 = medium hazard; 3 = high hazard), so that the following can be calculated: • The Hazard Factor Index (HFI), that is, the product of the weights and the hazard factors (Table 2): • The Control Factor Index (CFI), that is, the product of the weights and the control factors (Table 3): It is therefore possible to calculate the Hazard Index (HI) of each hazard centre (Table 4)     The system is used to analyze two different hazard levels, one linked to the possibility of the pollution of a water point by a DHC and the other which is generated by the synergic action, on the GWR, of different DHCs of the same type and which assumes a level of pollution that makes them unsuitable for human supply.
A comparison between the calculated HI leads to the definition of a priority list where a low HI means a low pollution hazard for a specific water point in the long term and a high HI implies a high hazard in the short term.
The calculation of the Territorial Hazard Index (THI) is carried out by multiplying the average HI value, expressed in thousands, related to each homogeneous DHC group surveyed, by the product of the assumed release surface (which is calculated in hectares) and the number of DHC that make up the homogeneous surveyed group: THI = (HI average/1000) × S[ha] × N hazard centers (1) The groundwater global pollution risk method, apart from weighing the single sources of pollution, considers the territory in which these are located. In order to do this, each source is assigned a reference Pollution Hazard Index (PHI), which identifies their potential hazard; subsequently, considering the tapping wells of the water supply system as Subjects at Risk (SaR), the Vulnerability of the Subjects to Risk (Vu sar ) is calculated together with the Value of the Subjects at Risk (Va sar ).
Considering the innumerable variables that have to be accounted for, the PHI, which was developed within the framework of the European Union COST 620 Action (AAVV, 2004), takes into account the quantitative and qualitative aspects involved in the procedure of establishing the weight to assign to the single activities (Table 5); 7 factor types have been identified.
Each factor has a weight that varies from 0-3, according to the impact it has on the specific activity. When the factor is 0, it is not present, in relation to the specified activity and the entity of the overall hazard is determined by summarizing the score.
In order to calculate the Vu sar and Va sar of the SaR, two distinct diagonal matrices are utilized.
The first matrix, which refers to Vu sar , is derived from the crossing of: • The Intrinsic Vulnerability degree, which is expressed though the SINTACS Index (Table 6) • The Exposure Level (Table 7), which is calculated from: • The distance of the well from the neighboring DHC • The position of these (DHC), in relation to the aquifer flow direction (hydraulic gradient) • The hydrogeological characteristics of the aquifer (hydraulic conductivity of the aquifer) At this point, the Vu SAR can be calculated on the basis of the crossing of the Intrinsic Vulnerability and the exposure, by applying the diagonal matrix (Table 8): The second matrix, which refers to Va SAR , is obtained by crossing, in a specific matrix of values: • The Basic Quality (Table 9), which expresses whether the resource is naturally scarce and impacted or of good quality The activity generates waste water characterized by a mainly organic type pollution 0-3 Water waste inorganic pollutants The activity generates waste water characterized by a mainly inorganic type pollution 0-3 Handling and/or storing of The activity implies the storage of materials classifiable as dangerous waste as provided for by 0-3 potentially hazardous materials Part 4of Italian Leg. Dec 152/2006, or other harmful substance that could damage the GWR Water-demanding activities The activity's productive cycle calls for the utilization of considerable quantities of water 0-3 Area or linear pollution The activity implies a potential, diffused type of pollution (involving an area) 0-3 Source: Tacconi and Zavatti (1999), modified Extremely elevated 80-100   • The relative value (Table 10), which is defined on the basis of the classes of the number of Equivalent Inhabitants (EI) supplied At this point, on the basis of the crossing of the basic quality and the relative value, Va SAR can be calculated by applying the diagonal matrix (Table 11): Elevated Well, field-wells, spring which feeds or can feed settlements with AE between 50,000 and 10,000 Vr 2 Medium Well, field-wells, spring which feeds or can feed settlements with AE between 10,000 and 1,000 Vr 1 Poor Well, field-wells, spring which feeds or can feed settlements with AE <1,000  In order to calculate the groundwater global pollution risk, it is necessary to multiply the values of Vu SAR , Va SAR and PHI by each other (Fig. 2), in order to obtain a range which identifies the levels of pollution risk levels. Table 12 shows the 6 risk classes that were defined in relation to a range of scores for each class.

RESULTS
In order to apply the methods outlined in the previous section, a Database was set up, composed of: • Maps of the study area on a Technical Regional Map (TRC), at a scale of 1:5,000 • Surveys of the activities that generate the greatest risks • Surveys of the wells tapped for agriculture and drinking water purposes The data processing was carried out in the Geographical Information System (GIS) environment. (Fig. 3) the weights relative to HFI and CFI were assigned for the HI calculation, as specified in Table 2 and 3. The following types of activity were identified and their relative release surfaces were estimated (Table 13).

Application of the Holman method
The formula (1) was utilized for the THI calculation.
In the Holman analysis, the "probability factor" has a particularly high weight. In the weight calculation of HFI and CFI, it was necessary to assume an accidental risk of discharge during the activities; two reference situations were therefore processed, i.e., a "critical" and a "normal" one and different weights were assigned to the single factors that make up the HI.
The activity of a dry cleaners is shown as an example in Table 14.
The application of the Holman model results in three distinct situations in relation to the two formulated hypotheses: • Categories of activities which present a low HI in both hypotheses. These consist of car-wash services, copy services, car repair workshops and body repair workshops, hospitals, clinical laboratories (veterinary) and metal work firms • Dry cleaners and cemeteries, instead, present a moderate HI, but only in situations defined as "critical", whereas in "normal" situations they have a low index • Fuel storage deposits, underground fuel tanks and service stations present a moderate or elevated HI in both cases Therefore, from the application of the Holman method, no particular activities emerge that present a risk of pollution, excepting for the activities listed in point 3.     3 3 3 3 3 3 3  81 27 2187  Service station 4  3 3 2 3 3 3 3  54 27 1458  Service station 5  3 3 1 3 3 3 3  27 27  729  Service station 6  3 3 2 3 3 3 3  54 27 1458  Service station 7  3 3 3 3 3 3 3  81 27 2187  Service station 8  3 3 2 1 3 2 3  18 18  324  Service station 9  3 3 2 3 3 3 3  54 27 1458  Service station 10 3 3 2 3 3 3 3  54 27 1458  Service station 11 3 3 2 1 3 2 3  18 18  324  Service station 12 3 3 3 1 3 2 2  27 12  324  Service station 13 3 3 2 3 3 3 2  54 18  972  Service station 14 3 3 3 3 3 3 3  81 27 2187 On the basis of the result obtained from the HI, two conclusions can be drawn: • It is possible to understand which activity categories present the greatest risk of pollution • It is possible to understand, within a certain group, which activities present a greater risk than others. In order to understand this more clearly, an example is proposed: taking the table of service stations into consideration (Table 15), the activities that concern creating a greater risk of pollution for the aquifer can be highlighted. For example, service station 3 presents a very elevated HI compared to station 12 In fact, if parameter C (Potential polluting load) is very elevated for both activities, parameters D and F are substantially different, since the two tanks were sunk at very different times: the former in the sixties-eighties and the latter towards the end of the nineties.
It follows that, should a quality analysis return a poor result due to the presence of pollutants (hydrocarbons), environmental engineers would be inclined to carry out further analyses at the site that is presumed to be a source of pollution.
By analyzing the THI parameter, it is also possible to understand which activities present the greatest risk by relating them to the territory within which they are situated. Even in this case, there is a marked difference between the various groups of classified activities. Practically all the "commercial or craftsman" activities present an THI that does not exceed 1 (considering the situation as "critical"), since the pollutant release areas are relatively modest. The situation foreseen for fuel stores, underground fuel tanks and service stations which have a release area of between 0.1 and 0.3 ha, is instead different and thus defines a risk of: • 1.33 for fuel stores • 0.92 for underground fuel tanks • 7.33 for service stations It is in fact the service stations that represent the greatest hazard for the GWR polluting risk, since they are present in large numbers and are often equipped with obsolete tanks.
Application of the groundwater global pollution risk evaluation method: the evaluation of the Global Risk was obtained by calculating the PHI, the Vu SAR and the Va SAR .
For the PHI (Fig. 4) calculation, the method developed as part of the European Union COST 620 Action is implemented with the data already utilized for the Holman Method in order to improve the analysis. In this way, the urbanized area presents a PHI of 9, but where activities with a pollution risk are installed, the PHI is assigned a greater value according to the craftsman or industrial activity carried out in that area.  The activities for which a PHI was identified are shown in Table 16.
In order to build the intrinsic vulnerability map, reference was made to a previous study in which the Vulnerability was evaluated utilizing the "SINTACS R5" Point Count System Model (Civita et al., 2001) which returns a numeric Vulnerability Index of 6 degrees.
The studied area presents a particularly elevated degree of vulnerability which varies from High (Value Vi 4) and Elevated (Value Vi 5), in the Aosta hills, to Extremely Elevated (Value Vi 6), over the whole Plain in which the city of Aosta is located.
The Exposure level map shows an Elevated value (Value L4) for the whole study area.
The Vu SAR cartography (Fig. 5), which is made up of the results of the previous analyses, presents values that vary from 6 (Extremely elevated), above all over the whole plain, to 5 in the Aosta hills where the Intrinsic Vulnerability is Elevated.
The basic quality map was built on the basis of the results obtained from the samplings carried out by the Regional Environment Protection Agency (ARPA) and the Politecnico di Torino The quality was generally reported as good (Value Q3), except for a well within the industrial area, which presents a Poor (value Q1) quality.
The socio-economic value map was plotted by calculating the Equivalent Inhabitants (EI) supplied by the urban water system and the obtained value is extremely elevated (index Vr 4).
The Va SAR map (Fig. 6) is made up of the previously presented cartographies and the obtained value oscillates between 3, mainly in the whole Aosta plain and 2, in the area adjacent to the well that indicates Poor quality (Value Q1).
The global pollution risk of the GWR (Fig. 7) cartography is the result of the product of PHI, Vu SAR and Va SAR . • Elevated or extremely elevated, for the whole urban and industrial area of the city of Aosta • Low or medium, for the areas surrounding the city, which consist of scattered inhabited settlements or areas that are mainly dedicated to farming or animal husbandry Nevertheless, some "alarming" situations emerge from a point analysis of the risk classes. The industrial area presents an extremely elevated risk value in relation to three main factors: • The vulnerability of the aquifer on which the industry has developed is extremely elevated • The basic quality of the water is elevated (except for one well showing poor quality) The urbanized area in the city of Aosta presents a High level of risk in relation to: • The pollution hazard index equal to 9 • The vulnerability of the aquifer on which the city is built, which is extremely elevated In particular, more or less extensive areas can be noted with a level of risk that varies from Elevated to Extremely Elevated. These are areas with economic activities that show a greater pollution risk to which Extremely Elevated PHI values are associated.

DISCUSSION
The analyses conducted show the need for an integrated approach with the territory planning and management (Wisconsin Groundwater Coordinating Council, 2002;Collin and Melloul, 2001;, which considers all the components associated with it, whether natural or anthropic.
It would be opportune to identify two performance scales relative to the different authorities and responsibilities: a territorial scale and a local one.
At local scale, with reference to GWR, it's necessary to operate through a series of consequent and integrated actions, which should be implemented starting from the planning activities related to town planning transformations. This is in fact the usefulness of the analyses carried out in this research: prevention of deterioration of ecosystems referring to their groundwater component (Haimes, 1984) which depends on the identification, dimensioning and interpretation of the anthropic impacts and loads accumulated and borne by a particular territory.
A definition of the limit-points of the load of urban structures on the environment could lead to a qualitative and quantitative improvement in the GWR quality. This implies drawing up a Dynamic Environmental Report (Part II, Title I, Art. 9, of Italian Law. Dec. number 152, dated April 3, 2006), throw the adoption of an Environmental Accounting System for the entire territory to which a general municipal urban plan refers.
The Environment Consolidation Act (implementing directive 2001/42/EC, concerning the evaluation of the effect of determined plans and programmes on the environment; 85/337/EEC, dealing with the environmental impact evaluation of specified public and private projects, as amended by 97/11/EC, 2003/35/EC and96/61/EC) -Italian Legislative Decree No. 152, dated April 3, 2006, Title II, Chapter I, Art. 7, states that the "Plans and Programmes (...) that (...) could have significant effects on the environment and on the cultural heritage (...), including the "(...)Plans and Programmes that present both the following requisites": "(...) concerning the sectors of agriculture, forestry, fishing, energy, industry, transport, waste and water management, telecommunications, tourism, territorial planning or soil use destination are subject to strategic environmental assessment".
In this legislative framework, a Strategic Environmental Assessment that could allow an Environmental Balancing of the pressures generated on the GWR by the anthrophized areas, is legitimized, through an actual Planning that is not only of an Urban Planning nature but also environmental.
It would therefore seem necessary to understand, evaluate and interpret the territory to which the urban planning refers, through the analyses proposed in this study and, if necessary, to implement them in a context of greater deterioration and vulnerability.
In implementing the Urban Governance policy it would therefore seem necessary to consider common shared urban development sustainability (RIVM and RIZA, 1991) objectives through the adoption of "best practices" which should be implemented in the drawing up and application stage of the Structural and Operative Plans.
First, it is necessary to identify the two fields for which it is important to adopt a new approach to the GWR management problem (Foster, 2001;Lashkaripour, 2003): • The first, for those parts of the city still to be urbanized (expansion areas) and for which it is possible to plan the uses of the soil, compatibly with the GWR • the second, in the already consolidated parts, for which it is more difficult to implement a strategic approach In order to implement the aforementioned approaches (Nouri and Malmasi, 2005), it appears indispensable to adopt the Environmental and Social Evaluation procedures related to anthropic impacts on the GWR system, in order to guarantee a balance between the quantity of the urbanized territory and the quality of the urbanization.
"Best practices" for the areas marked for urban expansion: • Planning the territory and defining the land use, on the basis of hydrologic principles: • Planning at a "Catchment area scale": it would be opportune to group together the craftsman and industrial activities with the same land use, compatibly with the environmental needs of the catchment area or drainage basin • The localizing approach: organize the different homogeneous parts of the territory, so that they interfere with each other as little as possible • The safeguarding approach: this aims at helping activities at risk to coexist in vulnerable areas. In this case, the perimeter of the area that release pollutants has to be identified, in order to determine the relative safeguarding areas • An integrated approach to management of the activities in relation to the territory in which they are located: • Storage and natural treatment of the water in urban expansion areas: in the parts of the territory in which tapping the aquifer causes damage to the environmental system, due to an insufficiency of the GWR, it is possible to: • Draw water in other areas and transport it by pipe lines • Set up the tapping of river water which, once returned to the aquifer and subsequently filtered through sand and clay, can then be drawn again • Treat craftsman and residential wastewater with purifiers, so that it can be reintroduced into the aquifer thus guaranteeing constant recharging of the aquifer • Guaranteeing adequate storage for the Water Resource, tapping it where it "falls": • Hold back the water helps to prevent floods: in some parts of the territory, it would be opportune to increase the water storage capacity by building artificial basins that ensure the exploitation of this resource over a period of time • Keeping a check on excessive underground polluting loads, to assure a high quality of water for the present and for the future: • Reduce the polluting load in selected areas, particularly where the aquifer is highly vulnerable, by means of appropriate planning or mitigating measures. Reduce subsoil contamination to acceptable levels, considering the vulnerability to pollution of the local aquifer, planning the uses of the ground and introducing selective checks on the DHS • Planning the drainage water treatment: it would be opportune for the urbanized and industrial areas to be impermeable so that pollutants dispersed in the soil are not be transported to the aquifer. It is therefore necessary to set up a system for the collection of rain water that is separate from that of the collection of sewage water from dwellings so that these two components can be separately and specifically treated for each different type of pollutant • Institutional structure at a social level: • A solid institutional structure which should rely on legislation that must: • Clearly and specifically define the water use rights, through the granting of licenses and by imposing taxes on the tapping of groundwater • Have strong social consensus (therefore avoiding the NYMBY syndrome) concerning the discharge of wastewater in the soil, the availability of land for the construction of waste disposal sites and other potentially contaminating activities CONCLUSION "Best practices" for consolidated urban areas: it is often problematic to apply the "best practices" outlined in the previous paragraph to consolidated urban areas, since the intended land use has already been decided upon and urbanization has already taken place. It is nevertheless possible to take precautions that could lead to a reduction in pollutants in the aquifer and, at the same time, reduce the risk of discharge in the subsurface, such as: • Upgrading the wastewater collection system, separating rain from sewage waters, in order to be able to treat them separately and more specifically • Treatment of wastewater from craftsman and industrial processing and their reintroduction into the aquifer, to guarantee the recharging of the GWR system • Total impermeabilization of the areas in which activities at greater risk of pollution are carried out and of those in which a situation exists where pollution has continued over the years, in order to avoid transporting pollutants to the aquifer. On the other hand and in general in the areas with a low risk of pollution, it is advisable to guarantee the highest level of permeability possible, to allow the aquifer to recharge and the concentration of the pollutants to be reduced • In the case in which the water demand is equivalent to the availability of the aquifer, but its exploitation would cause damage to the environmental system, artificial basins should be created for the supply or tapping of water from rivers • In the areas with greater aquifer vulnerability or where the calculation of GWR global pollution risk method is high, a relocation of the activities at greater risk to pollution should be implemented in favor of portions of land where the Vulnerability index is low or where there is already a preexisting pollution situation. As an alternative, companies can be obliged to carry out a series of structural interventions and checks to guarantee the prevention of GWR pollution. In these areas, once freed of the activities at risk, other activities considered "compatible" with the hydrogeological condition of the subsoil under consideration could be introduced.

ACKNOWLEDGEMENT
A grant issued by the European Social Fund (ESF) was used to carry out part of this study.