1 - GEOTECHNICAL INVESTIGATION REPORT - 150320 LAR Road Investigation Ridgewood Geotech 23042015_Rev1-Combined

2.       Fill – Silty Clay, medium plasticity, with some gravel and sand, dry, apparent stiff to
         hard, apparent cut to fill origin, of variable thickness (not encountered in AH15-01),
         overlying

3.       Residual Soils and/or Weathered Rock – ranging from Silty Clay with some gravel
         and sand, dry, to low to medium strength rock

Groundwater was not encountered in any of the auger holes on the day of the investigation.

5. 2 Existing Cut Batters
5.2.1 Section 61 (refer attached drawing REE-TFR-GT-002)
The major section of cut is approximately 200 m in length, and is up to about 4 m in height.
There is a 90 degree bend halfway along the cut, and re-profiling of the batter is expected to
improve sight lines. Observed conditions are shown on Plates 11 to 25, and indicate batter
angles commencing at about 45 degrees at the east end of the cut increasing to about 65
and 70 degrees in the central section of the cut, where batter heights are about 3.5 to 4 m.
The photo plates for this section are annotated with heights and slope angles. It can be seen
that ravelling of the upper layer of residual soil has resulted in undercutting of the crest in
places (see Plates 14 to 21). The residual material has slumped onto the weathered rock
faces (Plates 18 to 21). Again it is evident that the vegetation at the crest of the slope batters
is assisting stability.

5.2.2 Section 32 (refer attached drawing REE-TFR-GT-004)
Plates 1 to 10 illustrate conditions in this section of cut. Plates 1 to 4 show the presence of
distinctly weathered argillite with a layer of residual soil within the top metre. The batter slope
is at about 65 degrees with total height of 3 m.

Plates 5, 6 and 7 reveal an outcrop of bedded/foliated low strength argillite standing at 85
degrees with apparent bedding at 50 to 150 mm.

There is a large tree at this location (see Plate 5), and its removal would cause some
disturbance. It is also apparent that tree root structures are aiding stability to many of the
batters, particularly within the top layer of residual soil, which is present as a red-brown
gravelly clay.

Further outcrops of bedded arenite occur to the south of the large tree – see Plates 8 to 10.
A further tree is present close to the batter crest as shown in Plate 10. The batter angles in
this section of the cut are at about 65 degrees.

5.2.3 Section 12 (refer attached drawing REE-TFR-GT-005)
The existing cutting on the south side of Top Forestry Road immediately west of the junction
with Old Ceylon Road is about 120 m in length. The photographic record comprises Plates
26 to 38, and photos are annotated with observations on height and batter angle. Along this
section, slope heights are up to about 2.5 m, and the typical batter angle is 45 degrees.




1 As shown on Lambert and Rehbein drawing B14101-SK-004 Rev A and B14101-SK-005 Rev B
2
    As shown on Lambert and Rehbein drawing B14101-SK-004 Rev A and B14101-SK-006 Rev A


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