Description of interventions carried out
According to article 9, par. 1 of the Ministerial Decree 471/99, the owners informed the competent authorities that the soil might be polluted subsequently to mineral spirit spill and about the security measures adopted. The procedures to present the Characterisation Plan started.
In the first phase, the Characterisation Plan required to collect data about the production of materials used during the production cycle. Analyses from a former research showed the presence of hydrocarbon-impregnated soil around the mineral spirit tanks.
Underground tanks reach 1 ml below the flooring level and their capacity is 5 m3. They are installed under a shelter which is divided in two parts: the first contains a floor tank where the spirit used to be used to check the products - it was then recovered and injected back into the tanks; the second part was used as a storage area. The Characterisation plan included the proposal for a more detailed analysis through 3 piezometers, to be carried out up to 60 ml and 5 coring up to a variable depth of 10-17 ml.
The Conference of Services approved the Characterisation Plan and the Municipality of Aprilia released the approval of the Plan (General Protocol no. 3444) on 24th January 2002.
The investigation plan, as proposed in the approved Plan, took place from 26th February 2002 to 9th April 2004. The following analyses were carried out:
- N° 5 ground drillings at a variable depth of 10-17 ml spc for the ground sampling
- N° 3 piezometers up to a depth of 60 ml spc to take samples of ground water. Continuous analysis of interstitial gases to determine volatile organic compounds (VOC) through photoionisation, in order to determine what ground sections have to be sampled and what depth had to be reached.
Detailed reading of piezometer data and their statistical levels to reconstruct the local layout of the piezometric area.
- Drilling location
Piezometric drillings P1-P2-P3 and corings S1-S2-S3-S4-S5 were located as per table 01. Piezometers were arranged in the shape of an equilateral triangle with 20 ml sides and corings were carried out in a rectangular area having 10 x 20 ml sides
- Execution methods
Corings and piezometers were carried out using dry rotating core barrels with 127 mm-diameter pipes. During the execution, a photoioniser monitored the cores and samples were taken and stored in pots; tests were carried out through a probe which analysed gases by optical reading. Groundwater was processed, bottled in glass bottles and labelled.
- Topographic survey
It aimed at determining aquifer static levels in different phases, for piezometers P1-P2-P3, but also wells that were present in the area.
- Hydrogeological investigation to determine state of the aquifer
- Tests carried out on soil and groundwater
Soil parameters analysed:
- Aromatic organic compounds (benzene, ethylbenzene, styrene, toluene, sirene)
- Chlorinated solvents (chlorinated aliphatics and non-carcinogenic chlorinated aliphatics)
- Light hydrocarbons C< 12 and heavy hydrocarbons C>12
- Metals ( As, Cd, Crtot, Cr VI, Ni, Pb, Zn)
- According to all surveys carried out in the area surrounding the estimated contamination point, next to the East tank, the reference limit values were not exceeded.
- Soil samples from survey S4 show a strong concentration of light hydrocarbons, between 1-8 ml, and a lower concentration of light hydrocarbons (8-13 ml). There is also a low concentration of aromatic organic compounds and heavy hydrocarbons. Tables no.3 and 4 are here attached, and show a summary of the most significant results of this investigations.
- Groundwater is not contaminated, according to the parameters selected for the spill, but As parameters exceed the limits set by the Ministerial Decree.
According to the investigation: The polluted surface covers 64 m2 and corresponds to a square having coring S4 as its centre and whose sides are 8 ml long. Depth measured is approx. 12-13 ml; approx. 500 m3 of soil to be excavated.