• Capabilities: Site Evaluation and Restoration, Environmental Solutions, Environmental Construction
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Urban redevelopment of an industrial brownfield

Milan, Italy - Remedial design and turnkey remediation of two former refineries as part of a large PPP Urban Requalification project using sustainable remediation technologies.

150 million euros

of total investment in the development

A cost-effective remediation without surprises, delivered on schedule

Context

In one of Italy’s largest PPP Urban Redevelopment projects, the private investor Euromilano Srl and the City of Milan joined forces for creating a new urban quarter on the area of two former refineries in the Milan metropolitan area. The request of the public partner to establish a showcase with exemplary remediation results applying sustainable remediation technologies had to be reconciled with the needs of the private investor of short and predictable time schedule and economical sustainable budget.

The area of about 50 ha has been used by two petroleum refineries in the period from the early 50’s till 1990 and was highly contaminated with light and heavy hydrocarbons, aromatic solvents (BTEXs), chlorinated hydrocarbons and PAH in the soil and in the groundwater.

The challenge of the project was to create on the brownfield a public recreation park of 20 ha, the construction of a 1250 flats residential complex, as well as a large shopping center with a completely modernized transport connection, for a total investment of 150 million euros.

Role of Arcadis

Arcadis’ role in this project was to resolve all issues connected with the serious contamination problem of the area. After an initial phase of site investigation, risk assessment, remedial design and permitting support, client’s satisfaction and trust brought us the lump sum - turnkey contract for the whole site remediation.

Based on a detailed conceptual model obtained from site investigations, the remedial design focused on the combination of various innovative soil and groundwater remedial technologies, trying to avoid unsustainable actions such us off-site disposal.

The remedial actions performed contemporaneously in different areas of the site were: bioremediation on excavated soil, Soil Vapour Extraction in areas contaminated by VOCs, Bioventing, hydraulic confinement, free product recovery and creation of an internal landfill.

For on-site bioremediation Arcadis used a biopile approach:

• After the site preparation by setting tents for the bioremediation treatment (22,600 square meters of covered surface), the contaminated soil has been excavated in several different sub areas, for a total extent of 194,000 square meters, splitting the extracted material, by means of field measurements. To save costs and time a movable analytical lab for on-site analysis was located in the field;
• The contaminated soil, after being pre-treated and added with special biosubstrate and nutrients, was transferred to a treatment area beneath tents. Soil aeration and monitoring of hydrocarbons degradation was periodically performed;
• The treated soil banks with concentrations recorded below the remediation targets were extracted from the treatment area and used for backfilling operations and the realization of the urban park.
• The soil which was impossible to treat, due to the extremely high hydrocarbons concentration, was instead transferred to an internal landfill, with the capacity of 20,000 cubic meters, for disposal. 

For the remediation of deep soils Arcadis adopted an in situ approach:
• Specific Soil Vapour Extraction wells and Bioventing wells were installed and connected to extraction plants; due to the high VOC concentrations, the off gasses were treated by means of a catalytic combustor.
• Simultaneously, groundwater was also treated by both a hydraulic confinement system and a skimming free phase product recovery. 

In total over 250,000 tons of contaminated soil were treated with on site bioremediation and the total mass of hydrocarbons that was bilogically degradeted is of some 420 tons.

The in situ remediation with soil vapour extraction allowed, in two years, the physical extraction and combustion of over 12 tons of VOC. 

Results

The very early active involvement of stakeholders in the remedial design phase and during remedial actions, such as architects for residential buildings, park architects, urban planners, public authorities, residential representatives, etc. allowed to obtain several win-win solutions. For example the soil bioremediation was designed considering the soil requirements indicated by the park designer for planting soil. Using the right biosubstrates for the bioremediation allowed the usage of the treated soil as top soil for the park construction and generated cost savings for fertilizers and humic earth of about 0.5 million euros. Optimized allocation of underground constructions allowed reduction of contaminated soil excavation of about 20%. Adaptation of the remediation logistics to the construction activities allowed start of the construction of the shopping center 6 months ahead schedule.

The accurate design and monitoring of the biological degradation processes made sure that target levels were obtained in schedule. Mean soil concentrations after treatment of about 55% below target level and the fact that no contaminated material has been disposed off-site, qualified this project as an important showcase on the Italian remediation market. The private investor could start construction activities on schedule. The lump sum turn-key agreement for the remediation allowed him accurate budgeting without “surprises” and extra costs.



Outcomes

150 million euros

of total investment in the development

Questions about this project