Client: Local Authority, Central Belt of Scotland
Challenge: Remove hydrocarbon contaminated material from surrounding areas of houses built upon a former gasworks site. Reinstate existing landscaping.
Applied technology: Excavation and removal, then backfill with clean material
The solution: Soilutions were initially contracted to remove two metres of contaminated soil in the driveway behind two houses then install a soil vacuum extraction system. Initial excavations uncovered a ten metre diameter, four metre deep wall from an old gas holder containing hydrocarbon contaminated soil. Within the gas holder there was also a four metre deep brick and concrete tar tank containing heavy hydrocarbon contamination and some liquid tar. The corner of one house was founded upon the tar tank and straddled the gap between the tar tank and the gas holder wall.
Soilutions liaised with the client throughout the project providing various costed options as to how to proceed and further investigate the site as previously unknown structures were uncovered. The final works comprised:
- Liquid from the tar tank was pumped out and sent for disposal
- Solids in the tar tank were excavated and sent for treatment and disposal
- The tar tank was pressure washed and back filled with concrete
- Material between the tar tank and gas holder wall was excavated for disposal, including excavating underneath the house with the appropriate support works
- The gas holder was back filled with concrete
- The whole area was reinstated
Occupants were able to remain in their homes throughout the entire works.
Validation: Ongoing monitoring by consultants RPS.
Length of Project: 10 months.