Pride Park: from redevelopment of a landfill site to long-term operational experience

Abstract

The Pride Park site outside Derby had a legacy of contamination as a result of its industrial past. The site was previously used for industrial and domestic landfill, a gas works, railway sidings and gravel extraction. In the mid-1990s the site was closed and the heavily contaminated derelict land was remediated to allow site redevelopment. The work, undertaken by Ove Arup & Partners, Purac-Morrison and Alpheus Environmental included: a 10m deep, 3 km long cutoff wall encircling the site to prevent contaminant migration; 18 abstraction boreholes within the cutoff wall and linked to a ring main; a treatment plant receiving groundwater from the ring main and providing treatment prior to discharge to the River Derwent; and 18 pairs of monitoring boreholes to check groundwater levels inside and outside the cutoff wall to ensure that a level differential was maintained. Alpheus Environmental has operated and maintained the leachate treatment plant and associated boreholes on behalf of Derby City Council since late 1997. The treatment plant consists of an aerated balance tank, a flocculation/clarification stage with polyelectrolyte and ferric addition, pH correction, biological nitrification, sand filter, sludge belt press, on-line monitors and telemetry. The on-line monitors enable automatic borehole pump shutdown and recirculation of effluent within the plant in the event of specification limits being exceeded. Over the years effective management and implementation of a monitoring programme have enabled a significant reduction in operating costs for the client. These include over 25% reduction in electricity costs and 80% reduction in analytical and chemical costs.