Historic use of Millerhill Rail Depot, Edinburgh as a rail depot including maintenance yard, resulted in extensive and heavy contamination of soils and groundwater. The site was to be redeveloped as part of rail improvement works.
The key challenges in managing this project were the continued advancement of the construction project, collaboration with other stakeholders including construction personnel, establishing the extent of contamination to enable accurate design of remediation strategies, and providing a scope of works that met the requirements of the Client (Morgan Sindall and Network Rail), Local Authority (Midlothian Council) and Engineering Consultant.
In order to maximise the efficiency in soil removal and disposal, Soilutions completed additional soil and groundwater investigations to refine the understanding on the nature and delineation of contamination.
A combination of soil removal and treatment was established as the most practicable approach to mitigating the risk to the proposed development and the wider environment.
Following an initial groundwater treatment programme, skimming free product from near surface groundwater, an extensive soil excavation program was implemented and soils were disposed off-site or retained for use based on the results of the earlier delineation investigation.
During the excavation works, large foundations were uncovered and these were immediately incorporated into the mass excavations being supervised by Soilutions, to enable the development plans for the area.
Where mass excavations were not practicable, based on the development plans, a chemical treatment (Chemox) was applied to enhance natural degradation of residual hydrocarbons over time.
The project successfully enabled the development of the new rail maintenance infrastructure. Notwithstanding the compressed timeframe, Soilutions completed the work on-time and due to methods employed during the works, the costs of the project were well within agreed budgets.