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Pilot Action: Milan Functional Urban Area
Version 1
03 2017
D.T 2.3.4
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1.
Pilot Action Milan FUA
Milan FUA is one of the most densely populated areas in Lombardy (northern Italy). In
particular, in the FUA of Milan about 2.254.263 inhabitants live within 521 km
2
. The
northern area of FUA is characterised by a dense agglomeration of companies, and
especially near the Milano City historically (from ’50) are located many industries such
as automotive, refineries, chemical plants, still and tires production. Because of the
high hydraulic conductivity and the high groundwater withdrawal rate (public
withdrawal is within 8000 l/s), Milan represents a drainage area of groundwater and
many pollutants flows into municipality.
Especially the north-west area of Milan has since ’70 a direct effect on water quality
near water supply wells at pumping station in Milan. Thus, the area is hit by several
plumes, which deteriorate groundwater quality over decades. It is very important to
evaluate the extension of the plumes and distinguish areas within the FUA where
concentration values exceed the national threshold values.
a)
b)
Figure 1 - a) satellite view of the area of pilot action, b) GIS representation of the area
of interst: pilot action in violet and in yellow the FUA of Milan.
In Figure 1 are represented respectively a satellite view of the pilot area (a) and a GIS
schematization of the pilot area and the Milan FUA. As it is showed in figure 1 a) the
area is very densely anthropized and, consequently, populated.
Nowadays, the pilot action (about 12 municipalities within the violet coloured area with
617.773 inhabitants) is densely populated, and especially near the northern border of
Milan it is heavily industrialised. More than 34 contaminated sites are located in this
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zone. Of these about 10 are known or suspected to discharge chlorinated solvents in the
groundwater. Many plumes involve/affect/include both shallow and deep aquifer. It
became important to distinguish in this area the contribution of these plumes and the
diffuse contamination that afflicts the groundwater bodies.
A lot of single site investigation and remediation took place in the area in the last
decades. Additional field studies (hydrogeological and numerical model) were developed
within PLUMES PROJECT (ARPA for Lombardy Region) in order to identify hotspots
responsible of the plumes. Considering all monitoring wells hit by plumes, a
geostatistical analysis was performed in order to have/define/calculate a preliminary
value of diffuse contamination. In the pilot area many groundwater wells are built in
different aquifers, see Figure 2.
Figure 2 Representation of the groundwater monitoring wells in the pilot area: in violet
the deep wells/piezometers, in blue the shallow wells/piezometers and in green the
new piezometers that will be realized within AMIIGA project.
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Figure 3 shows the geological build-up through the project area. An aquitard (thickness
of 10 meters of low permeability) divides a shallow aquifer with a sand gravel material
with a relative high hydraulic conductivity from a deep aquifer, which is constituted by
fine sand. The separation of two aquifers becomes more and more discontinuous in the
norther part of Milan.
Figure 3 Geological build-up with the delineation of the FUA aquifers.
Because of this hydrogeological conformation, many plumes in the northern
municipalities can flow from shallow to deeper aquifers causing pollution in deeper
wells. In Figure 4, the Tetrachloroethylene concentrations monitored from 2003 to 2014
are represented. While the higher values (red colour-brown colour) could be
representative of hotspot contamination and associated to possible plumes extension,
the values within 10
µ
g/l could be linked to diffuse contamination. In the next step,
strategies and methodologies to handle the diffuse contamination and the contamination
plumes will be developed within the AMIIGA project.
N
S
SAND-GRAVEL (K=10
-3
m/s)
FINE SAND (K=10
-5
m/s)
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Figure 4 Tetrachloroethylene monitoring wells/piezometers – from 2003 to 2014.
The following activities are planned in FUA Milan:
×
Hydrogeological and groundwater monitoring data collection (hydraulic and
contaminant characterization for shallow and deep aquifer available until 2016) is
being updated.
×
Hydro-geological and numerical models will be updated in order to improve the
results of plume extension in pilot area.
×
Six monitoring wells in the deep aquifer will be drilled to optimize the existing
groundwater monitoring network in order to distinguish plumes and diffuse
contamination area (Four groundwater monitoring wells in the shallow aquifers and
two groundwater, see Figure 2).
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×
The Regional Implementation Group, that will be involved in the preparation of the
Groundwater Management plan for the FUA, will officially meet for the first time the
19 of April.
×
Three sampling campaigns will be done in order to survey the extension of plumes
(PCE, TCE, TCM, cis-DCE, vinyl chloride, methane, sulphates, iron cations,
manganese, nitrates, dissolved oxygen) and support their numerical transport
modelling. The CSIA analyses will be useful to distinguish plumes from a diffuse
contamination in the pilot area.
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