THE CHALLENGE:
A former printing inks factory requires surrender of the site’s Environmental Permit following decommissioning and demolition. Historical storage of solvents (principally Toluene) in underground storage tanks (UST’s) resulted in significant contamination of soils and groundwater within both shallow made ground and the underlying fractured bedrock, to a depth of up to 10.0mbgl. Removal of below-ground infrastructure and remediation of Toluene contaminated soils and groundwater to a ‘Satisfactory State’ was required in line with current SEPA guidance to support permit surrender. A staged approach to the remediation process was required, in tandem with Ramboll’s ongoing site characterisation, DQRA and Remedial Options Appraisal. Up-front pilot treatability trials to address the deeper contamination were required to confirm ’Best Available Techniques’ and support further in-situ remediation design to the source area and groundwater plume extending across 1Ha.
OUR SOLUTION:
Working under the Scottish regulatory regime, Soilfix obtained all relevant permits and licences for the required works, including a SEPA Mobile Treatment Licence. Stage 1 remediation and pilot trial works comprised:
- Two former toluene USTs cleaned, degassed and removed together with associated concrete cradles. Trial trenching to investigate a third suspected UST (none was found);
- Decommissioning and removal of the site’s oil/water interceptor;
- A large below ground concrete water holding tank was dewatered and backfilled;
- Two toluene soil hotspots were further delineated, excavated and removed off-site as hazardous waste under full Duty of Care;
- Pumping and treatment of impacted waters carried out prior to foul water discharge;
- Backfilling / compaction of voids with imported 6F5 primary aggregate;
- Installation of 8nr additional remediation and monitoring wells, using both vertical and inclined rotary drilling techniques. Rock core logging (supported by down-hole geophysical survey) provided detailed information on fracture orientation, size and frequency; and,
- Comprehensive in-situ pilot remediation trials carried out, including groundwater pumping & treatment trials, dual-phase vacuum extraction (DPVE) trials and clean water injection trials.
All works were completed with zero lost-time accidents / incidents—a key performance indicator (KPI) of this industrial client.
