THE CHALLENGE:
Demolition & remediation works are required to facilitate construction of affordable houses with private gardens at the former Fire Station and Library in Bromsgrove. Levelling-up funding has been granted to Bromsgrove District Council to develop this derelict site. Investigations had detected elevated concentrations of Per / Polyfluoroalkyl Substances (PFAS) on surface tarmac/concrete, basement walls, made ground and within drainage infrastructure, principally PFOA associated with historical usage of Aqueous Film Forming Foam (AFFF) during training activities. Contamination of groundwater in the underlying weathered Bromsgrove Sandstone formation, a Principal Aquifer had also been encountered.
OUR SOLUTION:
Working in collaboration with City Demolition, Soilfix implemented the following scope of supplementary assessment and remediation, fully in accordance with the Strategy agreed with the EA & Local Authority:
- Supplementary sampling of surface concrete / tarmac, previously inaccessible locations, identified hotspot areas and basement wall surfaces (using clean sampling techniques in accordance with PFAS Protocols) – used to refine the pre-remediation site characterisation;
- Controlled lifting of surface tarmac from the fire training area and watching brief over concrete slab and basement wall removal where impacted by PFAS;
- Controlled grubbing out of drainage infrastructure following PFAS contaminated sediment removal;
- Targeted excavation of identified PFAS source zones to target depths, followed by further chasing out of localised deeper contamination below a section of drainage run;
- Off-site disposal of segregated PFAS contaminated soils and aggregates fully in accordance with Duty of Care;
- Implementing stringent environmental controls and decontamination procedures to prevent cross-contamination by mobile PFAS compounds; and,
- Stage 2 remediation works (assessment & design in progress) are to comprise a betterment-based treatment solution, likely to comprise pumping & treatment of impacted groundwater followed by targeted injection of Colloidal Activated Carbon.
Soilfix successfully completed all Stage 1 works on programme with zero lost time accidents. The detailed design for Stage 2 (groundwater) remediation works is to be progressed upon conclusion of the project consultants’ groundwater monitoring programme (post-Stage 1 remediation).
