4.1 Characterisation of main pressures
The groundwater body D-2/D4 has been identified as being “at risk” due to diffuse pollution, the main reason being the infiltration of surface pollution from the urban area of the city of Riga. The pollution is observed mainly in shallow groundwater. Because of relatively high pollution levels in some sites, the pollution of petroleum products has been assessed as significant justifying the identification of the water body as “at risk”.
The pollution of petroleum products can originate from run-off from different sources linked to transport infrastructure (e.g. from streets and roads, fuel filling stations and parking places) or from industrial territories (with their own fuel filling facilities or petroleum tankers).
Some shallow groundwater sites also have historical petroleum pollution stocks in soils and groundwater, resulting from less strict environmental legislation during the Soviet Union period. Pollution has accumulated during several decades leading to very high contamination levels exceeding quality standards by 100 or even 1000 times in some sites. Most of these sites have been included in the official register of “contaminated sites”, which lists around 80
“contaminated sites” for the case study area. In addition, around 50 sites in the area have the status of “potentially contaminated sites”. And 70 of the “contaminated sites” and 30 of the
“potentially contaminated sites” face significant pollution from petroleum products.
As part of the pressure analysis, all main pollution sources causing pressure on the groundwater body were listed and grouped as follows:
1. Historical point sources that have formed pollution stocks in shallow groundwater. All shallow groundwater sites with petroleum pollution stocks accumulated due to past activities were considered for further analysis.
2. Current point sources forming pollution flows to shallow groundwater. The following pollution sources were considered under this group: fuel filling stations, petroleum stations and tankers, parking places (with more than 50 car places) and car
“cemeteries” (disposal sites).
Additional sources of potential pollution were also considered in the analysis:
• Run-off of petroleum products from streets and roads – if streets and roads do not have rainwater collection system, pollution infiltrates into soils and theoretically can reach also shallow groundwater.
• Non-used drill-holes as they offers the possibility for surface pollution infiltration into groundwater (such risk concerns organic pollution mostly but also petroleum products).
Pressures and impacts from these two sources are quite uncertain, in particular as no information is available about possible pollution loads from these sources.
The pressure analysis should help assessing the total pollution load for a given water body along with the contribution from each source/pressure. Such information is however not available for petroleum pollution loads in the groundwater body D-2/D4. There is also no model available for calculating petroleum pollution load into shallow groundwater. Thus, all pollution sources were characterized in terms of (likely) area of shallow groundwater polluted. The contribution of each source into the total pollution load was then assessed based on experts’ judgements collected during specific expert inquiries (see also Annex 1).
The summary on the main results of the analysis of pressures is provided in Table 2.
Table 2. Summary results of pressure analysis for the groundwater body D-2/D4
No of sites where pollution level in shallow groundwater exceeds current
1. Pollution sources that has formed pollution stocks in shallow GW in the past Fuel filling
2. Current pollution sources forming (potential) pollution flows Fuel filling
stations 140 34 (all belong to the group 1 because the
pollution has formed in the past) - Petroleum
stations and tankers
16 12 (all belong to the group 1 because the
pollution has formed in the past) - Parking places
(with more than
50 car places) 105
Not known, but assumed that pollution mostly has not reached shallow
groundwater** -
Car “cemeteries” 30 Not known, but assumed that pollution mostly has not reached shallow
groundwater** -
* Expert assessment based on specific expert inquiries
** Expert judgements or estimates
*** km of streets and roads in the city with no secured rainwater collection (assessed by experts from the authority responsible for rainwater collection system infrastructure - around 180 km of streets and roads require the building of rainwater collection network to meet an 100% coverage for the city)
Sources: Regional Environmental Board of Riga, the official register of “contaminated sites”, archives of experts, expert judgements
Table 2 stresses that around 70 hectares of shallow groundwater are polluted with petroleum products out of a total of 30 500 hectares for the city of Riga. This is less than 0.5% of the total groundwater body area. Experts estimated that historical petroleum pollution load accumulated in these 70 hectares accounted for more than 90% of the total pollution in the groundwater body, the rest originating from run-off from current pollution sources.
Overall, petroleum products are present in relatively small areas but with very high concentrations, leading in some cases to a permanent floating layer of petroleum products in shallow groundwater. Because of the insoluble nature of petroleum pollution, pollution will remain in shallow groundwater as long as specific measures are not taken for eliminating and removing these products. The pollution level in all problematic sites is too high for
shallow groundwater to be used for any human needs today or in the future. And in contaminated areas close to surface waters, there is a risk that shallow groundwater pollution reaches connected rivers, lakes or channels – with detrimental impacts on surface water ecosystems and on swimming/leisure activities. Furthermore, in highly contaminated sites located in the middle of city neighbourhoods, soil and shallow groundwater pollution are significant constraints to current and future urban planning and development. Figure 4 presents the spatial distribution of problematic sites.
Figure 4. Spatial distribution of contamination for shallow groundwater under the city of Riga
4.2 Expected future changes in pressures
As shown by the analysis of current pressures, the main source of petroleum pollution for the groundwater body is historical pollution accumulated in shallow groundwater. Clearly, because of the specific (historical) character of this pollution, this will not change in the future if no restoration measures are put in place. Future actions and restoration measures were identified by reviewing the current situation (e.g. restoration works carried out so far) and different policy planning documents. This was complemented by consultation with experts.
The following conclusions could be drawn:
• The main problem for restoring historical polluted areas is the absence of polluter responsible for this pollution and who should pay, and the lack of financial resources – as restoration measures are very expensive. Three potential sources of financing could be identified: EU structural funds with national co-financing (from the state budget), the budget of local municipalities and financial resources of private operators.
• The operational program for managing EU structural funds (CF and ERDF) for 2007-2013 (Priority “Small scale infrastructure”, Activity “Environment”)1 considers the restoration of several historically polluted territories, including 4 sites located in the case study area (Rumbula area). This are includes several contaminated sites. And financing allocated for restoring this site amounts to 7 million Euros. For the purpose of this analysis, it is assumed that two contaminated sites of the case study area will be fully restored (including measures for restoration of soils and shallow groundwater).
• The review of planning documents for the city of Riga led to the assumptions that 2 polluted sites would be restored with municipal financing by 2015. The Development Plan of the city of Riga prescribes that polluted areas need to be restored before starting new activities (as a minimum pollution in soils has to be eliminated and measures for groundwater restoration implemented). The main priority of the municipality is to restore areas located in the current (or planned) residential areas of the city. The Development Plan of the city includes references to restoration of two polluted sites2 – the Rumbula area and the polluted area named “Latvenergo TEC-1”.
And financing has been secured from the municipal budget for implementing measures in these areas (around 300 thousand euros every year from 2005 till 2012).
Thus, we can assume that two polluted sites will be restored till 2015 (1 site in the territory of Rumbula and the “Latvenergo TEC-1” area). Both soils and shallow groundwater would be restored in these areas.
• Because of the historical character of pollution, it is very difficult to involve private operators in restoring polluted areas as they are not obliged to carry out restoration measures. However, there have been cases with private operators being asked to contribute financially to site restoration. Based on the current situation and activities, it is assumed that one additional site will be fully restored by 2015 with private financing (one of the sites located in Sarkandaugava). Both soils and shallow groundwater will be restored in this site.
• Overall, it is then assumed that 5 polluted shallow groundwater sites will be restored as part of the current policies till 2015 (3 at Rumbula, 1 at Sarkandaugava and 1 named “Latvenergo TEC-1”). Only sites with high probability of being restored were considered. As compared to the large number of polluted shallow groundwater sites in the water body (97 sites identified in total), these planed restoration measures will not lead to significant pollution reduction.
With regards to current sources of pollution, the existing legislation prescribes that all fuel filling stations, petroleum stations and tankers as well as parking places (with more than 50 car paces) needs to be upgraded with: (1) anti-filtration decks, (2) rain water collection system, (3) own rainwater pre-treatment facilities and/or connection to public rainwater collection network. Besides, groundwater monitoring (1-2 times per year) will be mandatory for operators of fuel filling stations, petroleum stations and tankers requires. Experts
1 Source: “Infrastruktūra un Pakalpojumi”. ERAF un KF Operacionālā Programma 2007.-2013.gada periodam. Darbības programma Prioritātes “Maza mēroga infrastruktūra” Pasākumam “Vide”.
2 Source: “Ietekmes uz vidi stratēģiskā novērtējuma Vides Pārskats. Rīgas Attīstības plānam 2006.-2018.gadam”. Rīgas Vides Centrs, 2005
estimated that proposed preventive measures will be strict enough to prevent additional pollution to groundwater and that measures are likely to be implemented. It is worth stressing that the relative contribution from these sources to the overall petroleum product pollution is relatively small (around 5% - see Table 2).
Overall, we can assume that even if the number of potential pollution sources (e.g. fuel filling stations, parking places) slightly increases in the future, the total pollution load into the water body from these sources will not change in particular as preventive measures will be required for any new operator.
Measures concerning the closing of unused drill-holes and the expansion of the rainwater collection network were considered under the Baseline scenario. The Development Program of the city refers to the closing of 150 unused drill-holes by 2013 (around 110 thousand euros are allocated from the municipal budget for this purpose). The Territorial Planning of the city (for the period 2006-2018) specifies the expansion of the rainwater collection system in the city. By 2013, an additional 34 km of streets and roads will have rainwater collection networks (at total costs of around 23 million Euros).
The elements presented above lead to the assumption that the measures already considered in the Baseline scenario and for which financial resources have been secured will help reducing total pollution of petroleum products by around 15-20%.
4.3 Characterisation of main impacts
The draft proposal of a new Groundwater Directive specifies the importance of receptors in defining water quality objectives for groundwater.3 Thus, the assessment of impacts was carried out by identifying the main receptors affected by petroleum product pollution in the selected groundwater body and by investigating the negative impacts petroleum products might caused to receptors. The main receptors identified were: (i) (shallow) groundwater itself and (ii) connected surface waters.
There are many local shallow groundwater sites in the selected groundwater body where concentrations of petroleum products exceed quality standards for groundwater. As mentioned above, the total polluted area accounts for less than 0.5% of the total groundwater body area. But the level of petroleum products pollution in polluted sites is very high sometimes exceeding standards by up to 100 times. Some reduction in pollution may be expected by 2015 (considering the Baseline scenario results). But this will remain limited.
In some parts of the city where there is no access to public water supply network, shallow groundwater is used by households for their water supply. However, household uses are not affected by petroleum products pollution. And there are no other users of shallow groundwater in the selected groundwater body.
With regards to surface water, and as mentioned earlier, the interaction between groundwater, surface waters and terrestrial ecosystems is poorly investigated in Latvia. It is clear however that the interaction between groundwater and surface waters takes place in the case study area. Overall, 34 sites have been identified within the groundwater body D-2/D4 where pollution in surface water originates from groundwater (or where connected
3 For instance, the communication COM(2003)550 says that concerning other pollutants than nitrates, pesticides and biocides (for which standards are fixed by other Directives) good groundwater chemical status is reached when it can be demonstrated that the concentrations of substances do not undermine the achievement of the environmental objectives (good ecological and chemical status) for associated surface waters or result in any significant deterioration of the ecological or chemical status of these surface water bodies, nor should concentrations result in any significant damage to terrestrial ecosystems which depend directly on the groundwater body.
surface waters are “at risk” of being affected by groundwater pollution in the future).4 Although no surface water body has been officially identified as being “at risk” due to its connection to polluted groundwater, floating layers of oil products can be observed at different locations in surface water bodies. And pollutants continue to be discharged into surface water due to accumulated pollution in groundwater.
Information about pollution loads reaching connected surface waters is very limited.
Measurements in connected surface waters have been carried out and pollution loads estimated only for a few polluted shallow groundwater sites. However, the information is not sufficient for assessing the total pollution in surface waters coming from shallow groundwater for the case study area. Thus, it was assumed that the damage to surface waters is averted when pollution in shallow groundwater sites affecting surface water is eliminated.
The baseline scenario considers the restoration of 5 (out of 34) polluted shallow groundwater sites causing pollution problems for connected surface waters (today or in the future). Thus 29 sites would still continue discharging petroleum pollution into connected surface waters if no additional measures for groundwater are taken.
Experts stressed that the officially registered “contaminated sites” (where both soils and shallow groundwater are highly contaminated) occupy considerably large areas putting limitations to further socio-economic development of the city. Although the total area of officially registered “contaminated sites” is small as compared to the total territory of the city, there is a demand for using these areas for new developments. Due to changes in property rights, new landowners are not responsible for historical pollution. But they are facing constraints linked to existing pollution when willing to use these areas for new developments.
As soil and shallow groundwater pollution are highly inter-connected (shallow groundwater is sometimes very close to the soil surface), it is difficult to deal with both issues separately.
In light of the above the limitations for further urban development and development of economic activities was also considered in the analysis as indirect impact from the petroleum pollution in shallow groundwater.
4 Sources: (1) expert assessments, (2) “Priekšlikumi Operacionālās Programmas 2007.-2013.gada periodam projekta sagatavošanai saistībā ar piesārņoto vietu rekultivācijai”. SIA “Vides projekti”, 2005, (3) monitoring data from different studies and documents