Environmental remediations

CDS plant of Zoboli Renzo

Hexavalent Chromium remediation operational project
Owner/client Infrastrutture Lombarde S.p.A.
Type of service Environmental remediation
Location Verdellino Municipality (BG)
Period 2019 - in progress
Cost -

This area is located in the municipality of Verdellino (BG) and consists of a handicraft/industrial shed of a 200 sqm surface, currently disused but used in the past for chromium plating activities by CDS plant of Zoboli Renzo (and previously by the Company Cromec). The shed is located in an urban context of industrial destination.

Following the characterization investigations and subsequent monitoring (activities carried out in the years 2012 - 2020), it has been verified that the Contamination Threshold Concentrations (CSC) for the commercial/industrial use in soils and groundwater have been exceeded for some metals, including Total Chromium (Cr tot) and Hexavalent Chromium (CrVI).

Considering these results, the site-specific health-environmental risk analysis was prepared, submitted and approved by the appropriate agencies in December 2017. This processing showed some exceedances of the calculated Risk Threshold Concentrations (CSR).

It became necessary to prepare a Remediation Operational Project for soil and groundwater matrices.

Applicable remediation technologies

Excavation and disposal for surface soils and injection of reducing gas for deep soil and groundwater treatment.

Monitoring plans

In Operam, Post Operam and testing.

Cost and time analysis

Cost estimation of the intervention and definition of the work schedule.

Pro Iter Ambiente prepared the Operational Remediation Project pursuant to Legislative Decree 152/06 and subsequent amendments and integrations and shared it with the competent authorities.

The Operational Remediation Project prepared is composed as follows:

- Sintetic description of the investigations and monitoring carried out;
- Environmental context of the site including urban, geological and hydrogeological context;
- Description of the site conceptual model and summary of the results of the Risk Analysis;
- Description of the contaminants nature (CrVI and CrTot) with particular detail on their behavior in nature and environmental interactions;
- Screening of applicable remediation technologies: the technologies identified for the remediation of the site are the excavation and disposal of the hot spot detected in correspondence of surface soils and the injection of reducing gas for the treatment of deep soils and groundwater;
- Definition of preparatory interventions for the remediation including the safety of the shed (replacement of the roof made of materials potentially containing asbestos and disposal of waste present), the construction of n.5 new piezometers and the installation of a reducing barrier able to inject gas mixture to convert CrVI (very mobile) in CrIII (practically immobile);
- Description of the methods of execution of the remediation work, with particular reference to the methods of excavation, disposal and backfilling of the hot-spot, methods of installation of insufflation points, methods of timing and insufflation of reducing gases, execution of in-operam and post-operam monitoring and testing.
- Definition of the estimated metric calculation and chronoprogram of the activities;
- Definition of workers protection criteria.

Following the site characterization and the preparation and approval of the site-specific health-environmental risk analysis, Pro Iter Ambiente was commissioned to prepare the Operational Remediation Project for the site.
Currently, the project has been approved by the Competent Authorities and is being implemented.