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8739615 
Journal Article 
Investigation of contaminated land at a former sewage treatment works, its remediation and return to public open-space, Exeter, Devon 
Merefield, JR; Roche, DP 
2002 
1 
Proceedings of the Ussher Society
ISSN: 0566-3954 
GEOSCIENCE IN SOUTH-WEST ENGLAND, VOL 10 PT 3, 2002: RESEARCH INTO THE GEOLOGY AND GEOMORPHOLOGY OF SOUTH-WEST ENGLAND 
10 
3 
358-363 
English 
WOS:000180941100013 
Development of part of the Belle Isle Nursery site, at Trews Weir, Exeter for use as public open space required sampling for contaminated land assessment, due to its former use as a sewage treatment works. Once the site was confirmed to be contaminated, budgetary constraints necessitated a staged approach to its redevelopment. Government funding for remediation was also sought centrally through an initiative under English Partnerships. This is designed to assist in 'brownfield' site remediation where land is to be returned to public open-space. The sensitivity of the site due to its proximity to the River Exe required close liaison between the contractors, the City Council and the Environment Agency as the regulatory authority, throughout. Eight trial pits were used initially to provide access for soil sampling. Soil was taken at near surface, 0.5 m and 1.0 m, whilst sub-samples were selected for inorganic and organic chemical analyses. Results from the initial survey showed contamination of surface soils by several metals, including lead. Consequently, detailed surface soil sampling by soil auger was initiated. Sample density was measured at 30 m intervals and additional samples were taken adjacent to the initial sample sites. At the end of the study, the sampling density for the 3 hectare site was 83 samples. Contaminants comprised Pb, Zn, Cu, Ni and Cr with lead values dominant and reaching around 2500 ppm. Accordingly, mapping of the contamination employed Pb as the marker heavy metal, and using 1000 ppm Pb as the action level identified areas for remediation. Clean inert topsoil was imported to produce a barrier of some 600 mm depth over residual contaminated areas. This would provide a sufficient depth plus safety margin to ensure that members of the public would not come into contact with the underlying contamination. Hard standing (paths and seating) was also employed over contaminated areas where the engineered barrier would prove intrusive. Neutral to slightly alkaline soil pH made it unlikely that metal migration would occur in the future. The area was landscaped and opened up for public use providing access to the River Exe running through the city of Exeter. 
Pirrie, D