Site Investigation | Asbestos Remediation | Surface Water Management
£5.1M
K19D was previously used as a fabrication area during the construction of Hinkley Point A Power Station in the 1960’s. It contained surface and underground structures and services, including concrete plinths and foundations, underground septic tanks, foul water pipes, electric and fibre optic cables and redundant services. The asbestos took the form of cement bonded products, gaskets, rope and tiles plus friable spray coating and asbestos lagging; the works were undertaken under licenced conditions. Furthermore, there were areas of localised hydrocarbon impacted soil also containing asbestos.
Acting as a Tier 2 Contractor to EDF via COMA, John F Hunt Regeneration undertook two phases of work at the prestigious Hinkley Point C Site:
- Site investigation and formulating the remediation strategy
- Main remediation works
Site Investigation Works
The site was divided into 97 grid squares. Each square was investigated in general accordance with BS5930 by trial pitting to identify the presence of contamination. Soil samples from multiple horizons were tested in accord with the site re-use targets. The results were analysed and reported to the client in an interpretive report leading to the main remediation works where the principal contaminant of concern was asbestos in soil.
The initial site investigation was 95% accurate in determining the location of hazardous waste which allowed us to accurately price the remediation phase and was critical in enabling us to determine the length of programme for the client.
Main Remediation Works
These works comprised:
- Notification of the asbestos works to the HSE;
- Deployment of Mobile Plant Permit;
- Mobilisation and set-up of the welfare compound;
- Demarcation of ‘asbestos controlled work area;
- Breakout of hardstanding;
- Excavation of made ground;
- Segregation of material into stockpiles for re-use or removal off-site;
- Water management;
- Validation against Material Acceptance Criteria targets; and
- Final clearance and handover.
Project Management
Made ground was classified in-situ to shorten the work programme.
Excavation was carefully managed in accord with the Control of Asbestos Regulations 2012 (CAR2012). Each grid square was excavated and stockpiled with caution to ensure the predetermined waste classification was accurate. A Material Management Plan (MMP) was developed to manage the waste and its classification before removal from site. Materials were closely tracked following the MMP and daily works programme to enable quick sign-off from the client. Accurate waste auditing was conducted to enable daily progress reporting against the programme. HGV’s were booked a month in advance to ensure no delays occurred in the programme.
- Total cut: 19,000m³
- Hazardous waste removed: 9,400 tonnes.
- Non-Hazardous waste removed: 20,200 tonnes.
- Material retained for site re-use: 3,000 m³
- Programme of works completed 6-weeks ahead of plan.
Asbestos in Soils Remediation
The works were undertaken in accord with the JFH Asbestos Licence using experienced staff trained to work within a licenced ‘asbestos controlled area’ in accord with CAR2012. One grid square was found to be impacted by hydrocarbons at a hazardous level; this had to be removed to a different landfill that could accept hydrocarbon-impacted asbestos containing material. Validation of each grid square gave confidence that any remaining soil was suitable for re-use.
Surface Water Management
Surface water was treated on site using lamella clarifiers to capture sediment containing LNAPL/ DNAPL prior to discharge into one of the on-site Water Management Zones. Upon completion of the works, all plant and equipment was thoroughly washed down and cleared by the Asbestos Analyst before being permitted to leave site; water was removed from site as haz waste. Water samples were taken weekly to ensure compliance with the discharge consent.
Handover
The work area was handed back sectionally to enable follow on works to progress ahead of programme. Each area was subject to a modified four stage clearance procedure before the asbestos control measures could be removed and a ‘Certificate of Cleanliness’ issued.
We worked collaboratively with all stakeholders to deliver this complex project to the satisfaction of the Principal Contractor 6 weeks ahead of programme and under budget.
Dust / fibre suppression measures were implemented with these levels being monitored throughout the works.
Work areas were demarcated and notified to the HSE to control access in accordance with CAR2012.
Efficient material tracking / stockpile records enabled accurate forecasting of lorry numbers required to move material from site.