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Site History The sites former use as a boiler works resulted in heavy metal and hydrocarbon contamination of the soils. The site proposed end use was residential properties with gardens and flats with associated soft landscaping
Site Investigations
VertaseFLI carried out additional site investigations which identified metal and hydrocarbon hotspots. In addition a large quantity of broken sheet bonded asbestos was identified on site. Japanese Knotweed was also observed to be present across areas of the site.
VertaseFLI completed human health and groundwater risk assessments to produce site specific remedial targets for the remediation works. The human health risk assessment produced two sets of criteria those soils suitable for re-use on site beneath a ‘no dig’ barrier which would prevent mixing of the contaminated material and clean imported soils, and material suitable for reuse above the ‘no dig’ barrier.
Remediation Strategy and Works
A remediation strategy was produced and agreed with the regulators, this included a capped containment cell for the asbestos contaminated soils.
The remediation works comprised the following:
- The containment of 500m3
of asbestos contaminated soils on site, which were capped with a ‘no dig barrier. - Hand picking of asbestos fragments encountered elsewhere on the site.
- The excavation and offsite disposal of metal and hydrocarbon hotspots as part of a reduced level dig. The hotspot voids were validated and backfilled with chemically suitable site won materials.
- Earthworks comprising cut and fill across the site to finished site levels. This included the management of contaminated construction arisings so soils that posed a risk to human health were placed beneath the ‘no dig’ barrier, thus limiting off site disposal of material.
- Installation of a ‘no dig’ barrier.
- A contract completion report was produced to validate the remedial works which was signed off by the appropriate regulators.
- Treatment of the Japanese Knotweed identified on site through a series of spraying visits over a two year period.
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