This proposed housing development site had been used as a plant yard and contained below ground fuel tanks which had been leaking for a considerable period.
It would have been possible to remove an assumed, say 500mm of soil from around the excavation left by removal of the tank and then take samples for testing at a laboratory to see if the contamination had been removed. If these showed continued presence of contamination then the operation would have to be repeated.
To avoid the expense of removing too great a quantity of potentially contaminated soil and the uncertainty and delay of removing insufficient contaminated material insitu testing was used. When the insitu results indicated that sufficient material had been removed samples were taken for confirmation in the laboratory.
This scheme involved the development of 58 units of one and two bedroom flats with the provision of two disabled units, all timber frame construction. Thirty-one of the units are for shared ownership with the balance being for affordable general needs housing.
Demolition of the public house which had occupied the site had been undertaken and a spoil bund placed around the site perimeter, subsequently fly tipping had occurred.
A review of the original site investigation showed that there was contamination of the site with heavy metals and polycyclic aromatic hydrocarbons. An initial site visit identified the presence of asbestos fragments and also Japanese Knotweed.
Testing was undertaken across the site to determine the extent of soil contamination and thereby minimise the amount of material removed to landfill. A thorough survey of Japanese Knotweed on site was undertaken, it was established that this was located in the spoil bund and the contaminated stretches were identified and removed to landfill, timescales did not permit on site treatment. Verification testing was undertaken and after sampling the imported topsoil a concluding verification report was prepared confirming the suitability of the site for the proposed use.
The scheme was handed over on 24 July 2006 and subsequently won ‘Housing Project of the Year’ by Builder and Engineering Magazine.
Produce a phase 1 environmental desk top study and phase 2 intrusive investigation for a site at Worthing to assess the risks to sensitive receptors both on and off-site due to soil and groundwater contamination as a result of the proposed development.
The development comprises two semi-detached dwellings with private gardens and parking.