Forthbank Wind Energy Development - Partnerships for Renewables

Forthbank Wind Energy Development
13.3.52 Landfill gas migration monitoring points were installed off-site to the north of the main landfill
area. Monitoring records show the maximum concentration of methane recorded was 1.5%
v/v. The maximum concentration of carbon dioxide was also 1.5%v/v.
13.3.53 Leachate sampling is currently undertaken on a monthly basis at the landfill and the results are
held by Clackmannanshire Council. It is of note that leachate is currently extracted from the
site using a perimeter leachate extraction drain, installed in 1996. The leachate is collected in
two holding chambers prior to being pumped to the sewage treatment works.
Superficial Deposits
13.3.54 According to the BGS digital data provided by emapsite, the south-eastern part of the site and
access road are both underlain by reclaimed intertidal deposits (see Figure 13.3). The northwestern
part of the site is underlain by raised tidal flat deposits of Flandrian Age.
13.3.55 Previous site investigations state that the site is underlain by grey very fine sands, silts, organic
silty clays and clayey silts, these are locally known as the Carse Clays. These range in
thickness from 1m to 12m.
13.3.56 Trial pits extended in the area of the wetlands adjacent to the landfill were also within the
Carse Clays. This material was used to cap the landfill during the restoration in 2005.
13.3.57 A thin layer of Sands and Gravels underlie the Carse Clays, generally less than 3m in
thickness.
13.3.58 The Sands and Gravels are underlain by a layer of Boulder Clay (glacial till). However, this
was only noted at some locations on the site to the west of the site adjacent to the River Forth
and to the north of the main landfill site.
Solid Geology
13.3.59 According to the BGS digital data provided by emapsite, the bedrock beneath the site consists
of Lower Coal Measures. North-east/south-west trending faults are present at the northwestern
part of the site. The bedrock geology is presented in Figure 13.4.
13.3.60 However, the coal measures are expected to comprise a repetitive sequence of sandstones,
siltstones, mudstones and coal seams. The Passage Group sandstones underlie the coal
measures at depth.
13.3.61 No bedrock has been encountered in the previous intrusive investigations at the site.
BGS Data
13.3.62 Two borehole logs from the site were obtained from the BGS. The boreholes are located
adjacent to the track to the north of the landfill and on the edge of the site near to the mouth of
the Black Devon River.
November 2010 Chapter 13 Page 16
Copyright Partnerships for Renewables Development Co. Ltd 2010 ©