1、Remediation Of Leachate Problems At Arpley Landfill Site ,Warrington, CheshireH. ROBINSON (1), S. FARROW (2), S. LAST (3) & D. JONES (4)(1) Technical Director: Enviros Consulting Limited, Shrewsbury, UK. (2) Group Environment Manager: Waste Recycling Group plc, Lincoln, UK.(3) Technical Manager, Env
2、iros Consulting Limited, Shrewsbury, UK. (4) Technical Manager, Leachate: Waste Recycling Group plc, Chester, UK.AbstractWhen Waste Recycling Group (WRG) took over Arpley Landfill in Spring 1999, it inherited a site where leachate was up to 8 metres above consented levels. After tankering over 200,0
3、00m3 of leachate for treatment off-site, investing nearly 3 million in leachate extraction infrastructure and a state-of-the-art on-site leachate treatment plant, discharging into the River Mersey, the site is being transformed. The plant was commissioned in October 2001, and has already treated nea
4、rly 150,000 cubic metres of exceptionally strong leachate, to very high standards suitable for discharge into the River Mersey. Dramatic reductions in leachate levels have been achieved in all areas of the landfill site, with the great majority of locations either within, or close to, compliant leve
5、ls. This paper describes how the project has been implemented, and presents detailed operational data for the leachate management and treatment system. In terms of loads of contaminants being treated, the Arpley plant is almost certainly the largest leachate treatment plant in the UK, and represents
6、 a successful demonstration of use of Best Available Technology, to solve a serious leachate problem.Keywords: Landfill leachate，The leachate management1.ArpleylandfillArpley Landfill Site is located on the south bank of the River Mersey, west of Warrington, on 130 hectares of land, originally used
7、for disposal of dredgings from the Mersey and from the Manchester Ship Canal. Since it opened in October 1988, the site has received more than 10 million tonnes of domestic, commercial and industrial wastes, emplaced to depths of up to 30 metres, and continues to accept about 800,000 tonnes per year
8、 of primarily domestic wastes. Infilled areas are being progressively restored to a mixture of agriculture, woodland and public open space, being blended into the important 186 acre Moore Nature Reserve, which adjoins the site and is managed and funded by WRG (Warrington Worldwide, 2003). Wastes hav
9、e been deposited within three phases, Birchwood, Lapwing and Walton, with increasing degrees of containment, in keeping with advances in legislative requirements. The site is shown in plan in Figure 1, and Plate 1 comprises an aerial view of the site, looking due west.Figure 1:Arpley Landfill Site l
10、ayout showing different phases and liner types (plan courtesy of Golder Associates)Plate 1: Arpley Landfill, looking due west towards the estuary of the River Mersey showing the leachate treatment plant in centre foregroundSimilarly, tipping cells and phases had variable degrees of basal drainage in
11、 place. The original Birchwood Phase (18.5ha, 1988-1994) had no as-built construction drawings available, but it was reported that leachate drainage is by a herringbone of rubble drains. The subsequent Lapwing Phase (40.7ha, 1994-1997) comprises eight cells with a variety of drainage systems, each t
12、o a pumping chamber. The most recent Walton Phase (to be ultimately 45ha, 1997-), again has a variety of leachate drainage arrangements, albeit to higher standards than earlier areas of the site.When WRG acquired Arpley in Spring 1999, from 3C Waste (Cheshire County Council), leachate management at
13、the site was not under control, and there was complete lack of an effective infrastructure to enable adequate volumes of leachate to be extracted from the existing chambers. Substantial investigations and engineering works were necessary to sort out the problems which were faced.2.Initial Works At A
14、rpley2.1 Landfill gas controlAnother aspect of the site which required high levels of attention and investment at Arpley, was control of landfill gases. Initial works concentrated on improved control of landfill gas emissions the 8 million Arpley generation scheme is the largest landfill gas power s
15、tation in the UK, and capable of generating 16MW of electricity for export into the National Grid, enough to supply the needs of 16,000 households. It was commissioned in October 2000. Gas is extracted from over 200 wells, which had to be drilled and installed, via more than 10km of pipelines. Also
16、important in control of landfill gas, and of leachate generation, have been works to provide high specification capping to completed areas of filling. Reduction in levels of leachate across the site, was also necessary in order to allow extraction of maximum volumes of landfill gas.2.2 Leachate collection and extractionAs described, a wide range of leachate drainage systems has
