Envirotreat was instructed by Jones Brothers (JBHL) to provide technical assistance for the remediation works at a former Western Power (WPD) sub-station in Gorseinon (Swansea). WPD had decommissioned the former electrical substation and were surrendering the land for residential development.
There was anecdotal evidence of at least one oil spillage at the site in and about 2000.
The scope of works was based on this assessment of site conditions.
The scope of remediation undertaken consisted of:-
- Collection of a representative number of soil samples for analysis
- Assessment of analytical results and undertake a remediation options appraisal and WM3 assessment to facilitate offsite disposal.
- Supervise preferred remediation option of source contamination removal
- Collection of a number representative soil samples for delineation analysis.
Based on the site investigation, WPD requirement to surrender the land for residential development, and the potential risk to Human Health (site workers & end users) & groundwater, the following remediation strategy was proposed: –
- A reduced level dig of the areas affected.
- Validation testing to demonstrate the source removal and underlying ground did not present a future risk to Human Health and Groundwater.
- WM3 assessment of soils
- Offsite disposal
- Provision of a suitable “clean” capping layer on completion.
A WM3 assessment by Envirotreat based on the analytical testing was undertaken, this assessment indicated the soils to be non-hazardous (EWC 17.05.04).
Excavated soils were sent to the Treatment Hub for recycling.
A number of delineation samples were taken following the excavation works.
The results showed reduced levels of TPH and PAH.
Residual levels of TPH and PAH remain, however these are not considered a risk to groundwater and the protection of Human Health will be achieved by a suitable capping layer.