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Ground remediation by free product recovery and in-situ chemical oxidation

Client: Housing developer
Location: Aylesbury Vale, Buckinghamshire
Contract period: 18 weeks

A small industrial estate set in a rural location in Aylesbury Vale was previously occupied by a paint manufacturing business.  Various phases of investigation identified two areas of contamination, a small shallow zone of inorganic contaminated soils and a larger zone of organic contamination impacted with petroleum hydrocarbons, napthalene, chloroethene and methylbenzene.  Most of the soil and groundwater hydrocabon contamination was present at around 3.0m below existing ground level. Light, non-aqueous phase contamination (LNAPL) was also present in several monitoring locations.

The relatively small volume of inorganic contaminated soils was removed off site to a suitable disposal facility and was the most economic solution in this instance.  Treatment of the hydrocarbon contaminated area was carried out using a phased approach. Initially, a pump & treat system was installed to treat grossly contaminated groundwater as far as practical, followed by in-situ chemical oxidation (ISCO).

Approximately 100 remediation boreholes were installed across the plume of hydrocarbon contaminated soil and groundwater.  These initially facilitated the delineation of the contaminated plume with a high degree of accuracy ensuring all contamination would be identified and treated.  Boreholes containing LNAPL or grossly contaminated groundwater were fitted with pneumatically operated borehole pumps. Recovered liquids were then passed through a mobile water treatment system, the treated water being discharged to foul sewer.  During the second phase of treatment, modified Fenton’s reagent was used to address the dissolved phase contamination. 

The site works were completed in 14 weeks with a futher 4 week period of rebound testing.  All remediation targets were met and detailed in a validation report prepared for the Regulators.  Construction of the domestic properties has now commenced.

telluric bullet Our solution

  • Development of appropriate remediation strategy
  • Off site disposal of inorganic contaminated soils
  • Groundwater / LNAPL pump & treat
  • Chemical treatment by modified Fenton’s reagent
  • Progress monitoring and validation reporting
  • Compilation of validation report

The housing developer was able to continue with building work during site remediation, minimising costs and delays. Planning conditions relating to contaminated land issues were discharged.

A pdf version of this housing development remediation case study is available here