Barratt Southern Counties is developing the site for a high-end residential development of 97 houses and 2 apartment blocks. It contains an area of ancient woodland at its tip, which was once used as an area of unlicensed landfill by the hospital. A large volume of material had been end tipped into this woodland. This included excavated soil from hospital construction work, bulk refuse, incinerator waste, asbestos, green waste, oily residues and stands of Japanese knotweed.
RSK project manager Ben Winch comments, “Although the landfill itself was not going to be developed, the client was keen to transform it into an area of public open space.
“The wholesale removal of the landfill would have been an extremely unsustainable and costly exercise, but the other suggestion of fencing off the landfill and leaving everything in situ was an aesthetically unattractive option and not in keeping with a development of this prestige.
“Through negotiation with the Environment Agency and the local authority, we agreed on an alternative remedial approach: the partial removal and treatment of the landfill. Bulk refuse and asbestos material were removed from site and the remainder of the screened and treated finer material was replaced on the landfill site, stabilised and capped beneath a clean cover system. The Japanese knotweed impacted soil was reused within the landfill in a special lined cell. All other recovered materials were reused elsewhere on-site beneath roads and hardstanding.”
Out of a total 3,850 m3 of excavated materials, only 156 m3 of unsuitable material was removed to an off-site landfill or a waste transfer station, which equates to a total materials recovery of more than 96%.
Before: Excavation of upper landfill materials
After: Seeding taking hold on side slopes
Ben concluded, “The result was both visually appealing and practical, owing to the hard work undertaken by RSK, Soilfix and the client in transforming this area of wasteland into a grassed recreation area. This project goes to show that sometimes a simple consideration of the available options and sensible liaison with the regulatory authorities can prevent an expensive knee-jerk reaction and save a client a lot of money!”