Contaminated Land Project

National Developer, Kendal

REC was requested to investigate a derelict former timber yard which was to be developed as a retail garden centre.

The site investigation proved the presence of tributyl tin within the shallow groundwater system which was in hydraulic continuity with a neighbouring sensitive river.

Tributyl tin is an endocrine disruptor and can cause severe ecological impact.

The Environment Agency requested a comprehensive quantitative risk assessment model to be developed which provided an assessment of the on-site soil and groundwater remedial targets

Based upon the perceived level of risk, and the exceedance of site specific remedial targets, the EA requested the client to investigate a programme of source removal and groundwater treatment.

REC Ltd developed a strategy for the remediation of the site involving removal of contaminated soils and the treatment of contaminated groundwater by means of a permeable reactive wall. The design and performance criteria for the permeable reactive wall was designed by REC Ltd and Envirotreat, a specialist contractor.

The design of the permeable reactive wall was approved by the Environment Agency after the development of a working plan. The performance of the permeable reactive wall has been monitored by REC Ltd for over six months with routine chemical testing of the groundwater both 'upstream' and 'downstream' of the structure. To date, TBT concentrations downstream of the structure are negligable.

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