Forthbank Wind Energy Development - Partnerships for Renewables

Forthbank Wind Energy Development
Landfill History
13.3.45 Information on the landfill was provided by Clackmannanshire Council. The south-eastern part
of the site is situated on the Black Devon Landfill. The Black Devon Landfill was operated by
Clackmannanshire Council as a waste disposal site from 1979 until April 2004. The site
formed part of a land reclamation project to reduce the erosion of land at the junction of the
Black Devon River and the Forth Estuary.
13.3.46 The site was initially developed to accept the residual waste generated by the former adjacent
Alloa Incineration Plant and other wastes from local businesses (including sludge cake from
the adjacent sewage works) and other industrial activity within Clackmannanshire. The site
also received untreated domestic waste when the incinerator was closed for maintenance.
After the incinerator was closed, pulverised domestic waste was co-disposed with sewage
sludge. Sewage sludge continued to be disposed of at the site until the Scottish Water policy
changed and sewage sludge was treated at the sewage plant. When the incinerator closed in
1996, the site became the disposal point for Council collected household and commercial
wastes.
Landfill Liner
13.3.47 There is no landfill liner, however the landfill is underlain by clay superficial deposits which
were noted to be intact at the time of excavation. The clay superficial deposits were also used
to create bunds to separate out the landfill cells. Initially leachate from the site was discharged
through flap valve discharge valves into the Black Devon River and the River Forth. However,
the leachate is now collected in two subterranean tanks and pumped to the sewage treatment
works. The leachate is believed to be largely confined to the site. Water ingress into the
former landfill site is also believed to be occurring, as the volumes of leachate removed are
larger than expected.
13.3.48 The operational site was closed in April 2004 and restored in 2005. The restoration comprised
a Geosynthetic Clay Liner (GCL) capped with 0.5m of restoration clays and soils.
Site Investigation Data
13.3.49 From intrusive investigations in the south-eastern part of the site, the depth to waste is
between 5.9m below ground level (bgl) and 8.6m bgl (proven depth), with an unproven depth
of made ground at one location to 8.8m bgl. It was noted that the majority of locations were
underlain by superficial deposits of sandy clay, firm brown grey clay or firm brown gravelly clay.
13.3.50 Made ground deposits typically comprised of household refuse, plastic, metal, wood, wire,
timber and paving slabs.
Gas and Leachate Monitoring
13.3.51 The gas monitoring data shows the typical levels of methane are between 53%v/v and 66%v/v
and carbon dioxide to range between 0.0%v/v and 34.3%v/v. The most recent records are
from 2009.
November 2010 Chapter 13 Page 15
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