Page 58 - THE FIRE STATION

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Soil and subsoil The remaining backfill probably came from the construction of the
A detailed study of the contours shows how the altitude of the site Ring 3 motorway, as witnessed by a 1978 photo showing where
has changed over the years, first as a result of the backfill from the the backfill was being deposited.
colliery, and then as a result of the motorway construction.
The site’s altitude now varies from 149 to 157.5 metres, compared
A site analysis, based on maps and aerial photographs and track- to 140 to 148.5 metres in 1963, meaning that the landfill layer
ing its different uses over the years, allowed an assessment of the would seem to be between 10 and 19.5 metres thick.
nature and thickness of the backfill on which the fire station was to
be built. Second, there were no old mine shafts under the site. However,
there were two shafts under the slag heap and others on the north-
With regard to the projected development, the map and aerial ern and eastern edges.
photograph of 1963 showed that the northern section of the site
extended to the foot of the slag heap.This section thus had a layer The tunnels branching off these shafts were very narrow (1 - 2 m2)
of mining slag under it. and were assumed to have collapsed under the weight of the backfill.

157,5 m 156,5 m 149 m 156 m 156 m Hydrography
0,5 m 2,5 m 10 m 11 m 15 m There is no watercourse now crossing the fire station site.
139 m 145 m 141 m
19 m 11 m The Bataille stream used to flow along the northern edge of the
site, but it and its valley have now been covered over by suc-
138 m 143 m cessive layers of backfill. As already stated, the stream was not
correctly channelled during these previous works, with the result
Point 1 Point 2 Point 3 Point 4 Point 5 that a wet zone now exists alongside the A503 motorway to the
north-east of the slag heap.Together with various wet patches
Backfill dating back to the construction of the Ring 3 motorway elsewhere on the site, we can assume that the stream still flows
Backfill from mining activities (slag) underneath the backfill, coming to the surface when it encounters
Natural terrain underground obstacles.

Point 1

Point 2

Point 5

Point 4 Point 3

Evaluation of the thickness of the backfill layers Cross sections and geological map