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
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