Forthbank Wind Energy Development - Partnerships for Renewables

Forthbank Wind Energy Development
in the turbine foundations as well as cable routes and potential for explosion will be assessed
prior to construction. Site workers must avoid confined spaces and use appropriate PPE.
13.6.14 Pumping and collection of leachate monitoring is being carried out at the landfill site and the
leachate is believed to be contained within the site. Excavations for turbine foundations should
not impact on the existing arrangements for pumping of leachate. All infrastructure associated
with the leachate management system will be identified prior to construction to ensure that the
infrastructure is protected and the system is not compromised.
13.6.15 Information available to date on the leachate indicates that pH and sulphate concentrations are
unlikely to be of potential concern to construction materials. However, the laboratory analysis
was carried out some time ago and so further analysis of pH and sulphate concentrations in
the leachate is recommended. Should elevated concentrations be encountered, the use of
sulphate resistant concrete may be required.
13.6.16 Excavations through landfill waste will need to be isolated to ensure that leachate cannot
impact on groundwater in bedrock. Management of the leachate will also be required in order
to prevent leachate from entering the excavations. To protect the bedrock aquifer, it is
proposed that a pile cap be installed in superficial deposits at the base of the landfill. In
addition, should any contamination in made ground be encountered in the north-western part
of the site, isolation of potential leachate may also be required.
13.6.17 Dewatering of the landfill is expected to be required and a coffer dam may be required to
isolate the landfill leachate. Direct runoff from the excavation of the landfill will be captured and
treated within the landfills exiting leachate management system, if possible, otherwise
additional drainage and treatment will need to be installed.
13.6.18 Permission is likely to be required from the Coal Authority for any excavations or extension of
boreholes due to the risk of combustion in the coal seams. Additionally, the location of the two
adits in the north-western area of the site will be accurately positioned prior to construction to
ensure that the turbine foundations do not impact on the adits.
13.6.19 Excess runoff, from areas outside the historic landfill, will be drained into an infiltration trench
or swale. Infiltration trenches create an underground reservoir due to the excavated trench
being backfilled with clean stone. Runoff directed into the trench will gradually infiltrate back
into the soil. If infiltration trenches are properly maintained they can significantly reduce the
volume of suspended solids and pollutants in the runoff. If the volume of runoff exceeds the
capacity of the infiltration trench or ground conditions are unsuitable, swales will be
constructed to attenuate and convey the runoff away from the excavation before being treated
in a settlement lagoon.
13.6.20 Treated water can also be discharged onto vegetated surfaces and directed away from
watercourses and drainage ditches to avoid direct entry. For discharge onto rough grasslands
to be effective the discharge must be spread efficiently, for example using spray irrigation ‘Rain
Guns’. The latter provides a means of rapid and flexible deployment of discharge points.
13.6.21 Material removed during the excavation of the turbine foundations will be stored nearby in such
a manner that it does not cause pollution. This material will be removed from the site and
November 2010 Chapter 13 Page 33
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