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This Environmental Impact Assessment has been prepared by Safege and by
Institut za Varstvo Okolja (Environmental Protection Institute of Maribor) for
Aquasystems d.o.o. in order to comply with the European Bank for
Reconstruction and Development's (EBRD) environmental policy and procedures.
1. General settings and present situation
The City of Maribor and surrounding urban area are located along the Drava
river in eastern Slovenia. Maribor has a population of about 134,000
inhabitants. Maribor is an important trade and industrial centre and has its
own university. The surrounding countryside supports a range of agricultural
activities including cultivation of grain, vegetables, beets and vines.
At present, most of Maribor's domestic and industrial effluent is not treated
and is discharged directly into the Drava river system, polluting and
seriously degrading the surface and groundwater systems downstream of the
City, including specifically the aquifer downstream of Maribor from which the
City gets much of its drinking water.
There is a strong local interest in improving this unacceptable situation. The
Maribor Waste Water Treatment Plant (WWTP) project stems from this need to
improve the environment and particularly the Drava river system.
2. Purposes of the project
The main objective of the Maribor Waste Water Concession Project is to provide
for the construction of a waste water treatment plant for the City of Maribor
and its surrounding area. This will enable:
the treatment of most of the domestic and industrial waste water from the
Maribor area in order to improve the area’s general environment and
particularly the surface and ground water systems,
full compliance with local and EU regulations, in particular with the European
Commission Directive of 21 May 1991with regard to urban waste water treatment,
and with the Regulation on Emission of Discharges of Waste Water from Urban
Waste Water Treatment Plants (The Official Gazette SS,n0. 4/93 and 3/96), the
treatment of sludge for disposal or storage in a specially designated area
(off site).
3. General description of the project
The WWTP will extend over 6 hectares of land which is currently under
agriculture. The possibility of extension over a further 4 to 5 hectares is
under consideration. The site is located at a distance of around 7 km south
east of Maribor City.
The closest settlement is the town of Dogose, some 1.5 km upstream of the
site. The closest houses lie about 500m north of the site.
The WWTP will have the following characteristics:
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a design capacity of 190,000 population equivalents for a complete three-stage
treatment procedure
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maximum waste water inflow rate of 5,000 m3/h for treatment levels 2 and 3
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maximum waste water inflow rate of 7,000 m3/h for treatment level 1
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the effluent will be discharged into the hydro-power channel in normal
conditions. In extreme storm conditions (incoming sewerage water > 7,000
m3/h), the surplus waste water will be diverted into the Drava river.
The waste water treatment process will include three distinct levels; the
first level will consist of mechanical cleaning, the second level will include
biological processes through activated sludge to remove carbon and treat
sludge, the third level will upgrade the effluents in terms of nitrogen and
phosphorus removal.
The entire process, buildings and associated installations will comply with
local and European regulations:
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the whole treatment line will be constructed to ensure that it is leak free
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treatment chemicals will be stored in specially designed areas; a significant
portion of the treatment process will be automated
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the treatment chemicals used will be to EU approved standards
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noise and odour minimisation systems are included in the project
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sludge will not be stored on the site for any length of time
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health and safety measures will be taken for worker protection
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proper training will be provided to the workers to enhance plant optimisation
and security on the site.
The specific concession project does not include the construction of the
sewage collector (which is being arranged by others with support from EU Phare
funding). It also does not include for the long term disposal of the sewage
sludge which is the subject of further studies and arrangements currently
being undertaken by the Municipality of Maribor, and which will be the subject
of a separate environmental impact assessment. However, sludge removal from
the WWTP site will in all cases comply with EU and national legislation.
4. Phasing of the works
The WWTP will be built in three phases corresponding to three distinct
treatment levels:
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Phase 1
Construction and implementation of the pre-treatment
process including mechanical processes. This first phase will be implemented
within the first two years.
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Phase 2
Construction and implementation of carbon removal and
sludge treatment processes. This second phase will be completed within the
first three year
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Phase 3
Implementation of tertiary treatment to upgrade
nitrogen and phosphorus removal. This third phase will be implemented within a
eight year time span.
5. Compliance with EU and local legislation
AQUASYSTEMS d.o.o. will comply with both EU and Slovenian legislation.
The Maribor WWTP effluent quality will meet both the standards set by the 21
May 1991 European Directive and those set by local legislation, and more
specifically the Regulation on Emission of Discharges of Waste Water from
Urban Waste Water Treatment Plants (Environmental Protection Act - Official
Gazette SS, N°4/93 and 3/96). Where uncertainty exists between the two sets of
legislation, the more stringent requirements will be met.
6. Impact Assessment
The main potential impacts of the project on the environment include:
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impact on surface water
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impact on soils and groundwater
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impact on the landscape
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impact on amenity (odours, noise, traffic)
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impact on natural habitats, fauna and flora,
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impact during construction
All of these potential impacts have already been taken into consideration in
the design of the WWTP in order to limit their effects on the environment. As
previously mentioned the plant will abide to the most stringent criteria of
European and national legislation.
Impact on surface water
Possible impacts on surface water could occur through:
The risk of chemical spill affecting surface water is negligible because
chemicals will either be stored as solids in specially designed and designated
storage areas or as liquid chemicals in watertight containers, again in
specially designed and designated storage areas, and most handling will be
mechanised. Furthermore storage areas will have closed loop drainage systems.
Sludge discharge into the surface water system will not occur because sludge
will not be stored on site for any length of time. Nevertheless, the sludge
handling area will be watertight and equipped with a closed loop drainage
system with a possibility of recirculation through the treatment line.
The liquid effluent will be discharged into the hydro-power channel.
Calculations have shown that even in the best natural water quality conditions
(upstream from Maribor), the effluent will have a negligible impact on the
surface water system both in terms of quality and quantity. In fact the
treatment process and diversion of treated effluent into the hydro-power
channel will have a major positive impact on the environment as it will
prevent uncontrolled direct discharges of untreated municipal and industrial
effluents into the Drava river system, as is now the case.
Impact on soils and groundwater
The project could potentially affect soils and groundwater through:
The risk of chemical spill and sludge percolation will be negligible for the
reasons already explained above.
The entire treatment system from the plant inlet to the plant outlet will be
watertight; the risk of waste water percolation into the ground is therefore
negligible.
Building deep foundations will require groundwater pumping: the lack of data
prevents an assessment of the pumping effect on the aquifer. It is reasonable
to assume however that the effects of pumping will be moderate to negligible.
They will in any case be temporary.
Flow exchanges between surface water and groundwater will contribute to
improve groundwater downstream from Maribor as surface water quality will
improve.
Impact on landscape
The WWTP will not have any significant impact on landscape as the plant itself
will not be visible from any housing units, nor from most of the neighbouring
areas.
Great care have been given to the Plant’s general aesthetics: essentially it
will be hidden from view by green vegetation, which will be kept neat and
clean.
Impact on amenity
Containment of noise emitting engines or activities in sound-proofed areas
prevent any will result in no additional noise impacts away from the site, and
in particular in the vicinity of the nearest existing housing units.
Odour removal systems included in the project design will prevent olfactory
nuisances.
Traffic will not significantly increase in the area of the WWTP, except on a
temporary basis during the construction phase.
For reasons mentioned above the WWTP is expected to improve surface and
groundwater quality. As such it will contribute to remove odours arising from
the Drava river’s poor quality water.
Impact on natural habitats, fauna and flora
There are no sensitive, nor any unusual species of fauna or flora in the site
area ; this area is indeed primarily devoted to agriculture. The WWTP site is
in an area which is likely to be designated as the Drava Nature Park, a
"landscape park". According to available information, the park status is
currently under consideration (non official). For reasons explained above the
WWTP will have a positive impact on the Park.
Impact during construction
These are essentially restricted to additional traffic and noise generation by
construction equipment and machinery during the construction phase. Nuisances
generated will be negligible for the local population.
7. Overall assessment and mitigation measures
The Maribor WWTP will include modern technology for operation and control. It
will comply with the most stringent requirements of both the EU and Slovenian
legislation. Environmental aspects have been taken into account from the start
of the design of the project.
Due to all the control, fail-safe and protection measures and steps included
in its design, the WWTP will have only minor negative impacts on the
environment, some of which will be restricted to the periods of construction
activity.
Once operational, it will have a major positive impact on the environment as
it will allow a great improvement in surface water quality and possibly
groundwater quality. This improvement will be gradual through time and will
extend over a 8 year time span according to the project’s three phase
implementation.
To secure this advantage, the following recommendations are made:
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monitor the detailed design and construction of the WWTP to ensure that work
is carried out to high standards and that the treatment works are likely to
remain watertight throughout the design life;
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monitor the aquifer pumping during the construction phase;
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impose good working practices on all contractors to minimise noise emission,
minimise traffic and keep the site as clean as possible during the
construction phases;
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set up a monitoring system to check that all parts of the plant continue to
meet Slovenian and EU requirements;
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explain the WWTP benefits to the public;
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install a piezometer system to monitor the shallow groundwater aquifer
downstream of the WWTP site.
8. Public information and consultation
The concept of the Maribor WWTP project originated in the late 1980s. At this
time a number of sites were under consideration, including the one currently
selected. Since this time extensive public consultation has taken place both
to select the site and to find ways in which to mitigate the environmental
impact of the construction and operation of the plant itself.
Key meetings of the Executive Committee, the Municipal Assembly, the City
Council and other associated bodies in Maribor took place in 1993, 1994 and
1995. The Concession Act which was the key decision required to commence the
formal process of implementing and financing of the WWTP was passed by both
the Assembly of the Municipality of Maribor and by the Assembly of the Local
Communities on 30 June 1994 and by the Labour Assembly on 7 July 1994.
Both before and after that time, an extensive public consultation process,
including public meetings and discussions, has taken place, in full compliance
with the Slovenian legal requirements. This process has been supervised by the
Ministry of Environment and Physical Planning, who is responsible for the
regulation of the physical planning process. Following a formal consultation
process and the answering of a number of questions raised the government
approved the Land Use Plan on 18 July 1994.
Most recently public meetings have taken place as recently as September 1998
to discuss details of the WWTP project with the local population. The
consultation process is on-going.
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