Description of the job
Remediation of polluted soils by Bioremediation technique
The characterisation plan realised in the warehouse's solvent area of the Aerosekur plant identified the presence of pollutants, mainly hydrocarbons. (see Characterisation plan sheet).
The effective remediation method used was a bioventilation process system, which optimises the local biological activity by injecting air, water, nutrients and oxygen into the subsoil.
According to the treatability tests performed in a laboratory on samples taken from the worksite, the contamination reduction programme aiming at bringing the levels below the limits set by the applicable regulation was respected as follows:
- 20% after 30 days
- 45% after 60 days
- 72% after 120 days
- 92% after 150 days
- below the limits after 180 days
Technical data
Volume of soil treated 530 m3
Data
Customer: AEROSEKUR S.p.a.
Area: Aprilia (LT)
Construction site: Manufacturing plant
Work Termination: end of 2005
Description of the job
- Asbestos-containing materials mapping within the decommissioned buildings and remediation intervention planning
- Demolition of decommissioned structures
- Removal and disposal of soil found to be contaminated during the characterisation first phase in this area
- Characterisation second phase and remediation intervention planning
Given the significant quantity of soil treated, careful planning was needed for the excavation geometry, the temporary storage areas for non-contaminated soil, which were to be re-used in this area, and for soil to be analysed more in depth.
Materials to be characterised were stored using waterproof HDPE sheets so as to guarantee the protection of the subsoil from any contaminant.
Difficulties faced
During the first soil removal phase, a second in-depth contamination front was discovered, since it was not identified by the initial characterisation. The second characterisation made it possible to identify this front in detail and to plan the best solution to the problem.
Critical points
The depth of the excavations (up to 10 metres) and the state of neglect of the area.
Added value of the activity
The second-phase characterisation made it possible to better identify the causes and the state of contamination of this site, so as to optimise the interventions and provide monitoring points for the water conditions.
Cost of the works
1.200.000 Euro
Technical data
Engineering managers:2
Worksite managers: 2
Specialised workers: 6
Waste disposed of
Contaminated soil and rocks: 20,000 m3
Friable asbestos-containing materials: 1.5 tons
Cement-asbestos materials: 50 tons.
Other waste: 1,500 tons.
Data
Customer: IM.CO. S.p.a.
Area: Milano - Bruzzano
Construction site: Area “Ex-Montecatini”
Work Period: 12 months
Work Termination: September 2005
Description of the job
The area to be treated was the landfill in the Municipality of Siena. This contaminated area contained two main types of waste:
- the first contained shredded waste of different types (wet waste, plastic and urban waste)
- the second was made of dioxin-containing ashes.
Two different codes were used to classify these types of waste
- EWC 191302, which identifies solid waste from remediated areas.
- EWC 170504, which identifies non-dangerous soils, whose dioxin content is below the risk level
The shredded material and the dioxin-containing soil were in different areas.
Critical points
- Time available was limited and this required careful organisation to removal and dispose of the soils so as to create a continuous flow from removal to disposal. This continuous flow made it possible to optimise the efficiency of machines and eliminate waiting times. The excavation pace produced 600/800 tons of soil per day on average, corresponding to approx. 25 trucks per day. This method made it possible to remove and dispose of all of the material in five months.
Difficulties faced
- Due to the scope of the job a workers dormitory, changing rooms and shower rooms were set up at the work site,. An office and a workshop were also built for the extraordinary maintenance of vehicles.
A truck wheel washing installation was set up to prevent pollutants from being taken out from the worksite as much as possible . Runoff water was also treated.
Worksite setting up
- Within the excavation area there were several underground utilities, such as gas network and sewage network, whose position was not always clearly defined and this required great attention to prevent damages. This situation caused a slowdown of excavation phases and required the continuous excavation-disposal flow to be adapted in order to avoid waiting times
Technical data
- Excavation volume: 43,000 m3
- 1 work site manager
- two 1 m3 bucket bulldozers
- one 140 hp tracked excavator
- six 300,000 kg trucks
- Amount of the contract: 1,112,000 €
Data
Customer: Municipality of Siena
Area: Siena
Construction site: intervention of environmental decontamination at the former "Mattonaia and Cerchiaia area", with landfill disposal
Work Period: 5 months
Work Termination: February 2004
Description of the job
- Remediation of the whole area and buildings. The decommissioned plant used to produce Cement-Asbestos products. The storeyards were used to store and handle the products and contained large quantities of reinforced concrete products, contaminated by reinforced concrete scrap and rubble, which were collected and disposed of. The buildings hosted the production and were made of structures covered with reinforced concrete roof sheets.
- The contamination of the buildings required the following remediation operations:
- Reinforced concrete roofing
- Reinforced concrete waste and scrap on the floors with a similar situation as in the outer area
- Mud, friable asbestos plaster and raw materials in their tanks, in the furnace area and in the raw material area.
- Urban-like waste on the whole area
- Reinforced concrete sewers and asbestos-contaminated soil
Critical points
- The area was huge and it was impossible to implement static confinements (apart from the enclosed areas containing the furnaces and the raw materials).
- It was difficult to classify the soils from the sewage trenches, since they were very heterogeneous.
Innovative solutions introduced
- A SAFE-CAR suction sweeper was used, fitted with localised confinement absolute filters. Thanks to its accessories (extensible pipes), this machine can vacuum-clean both flat surfaces and non-accessible areas, such as holes and overhead surfaces. The safe and high-level performances of this machine made it possible to carry out this remediation in a short time and at a reasonable cost. During the operations, the levels of airborne fibres both in the working area and on the border of the property were constantly monitored: this made it possible to not build static confinements, since this was almost impossible, and to ensure the fibre level was below 2 ff/l for the entire duration of the project.
- The removal of friable materials from the raw material area and the furnace area was carried out within confined areas. The roofing remediation was carried out using basket platforms. Amount of the contract: € 5,195,556
Technical data
Area treated:
- 150,000 m2 (total surface of the area)
- m2 40,000 (indoor surface)
- N° of worksite managers: 1
- total N° of workers: 12
- approx. 7,000 tons of 2A type reinforced concrete materials and scrap
- approx. 250 tons of 2C type asbestos-contaminated soil
- approx. 220 tons of friable asbestos to be incinerated
Data
Customer: Bagnoli SpA
Area: Bagnoli (Napoli)
Construction site: sito dismesso ex Eternit
Work Period: 14 months
Work Termination: December 2000
