20013-001-Rev0 Flooded Gum Pl - geotech report

Mr Andrew Jensen                                                                                       20013-001-Rev0
                                                                                                       4 February 2020

No groundwater was observed on site during the site walk-over assessment.

2.2    Topography
During the site walk-over, topographic features specific to the site were noted, and ground slopes were
recorded using a hand-held inclinometer.

As illustrated in Text Figure 5 below, the site generally slopes down to the north at inclinations of between
11° and 18°, with the most gently sloping terrain located in the south-eastern part where the ground surface
likely sloped at about 5° to 8° to south (prior to recent earthworks to form the building pad). A ridge with a
relatively level crest runs east to west above the southern boundary of the site.

There is a broad central drainage line which propagates as a generally linear, grassed, surface depression
(as shown in Text Figure 6).

Earthworks have recently been carried out to form a building pad in the south-eastern part of the site where
natural ground slopes were the flattest. The building pad was approximately 25 m wide and 50 m long. The
southern side of the pad was formed in cut up to about 3 m deep with fill estimated to be up to about 2.5 m
high on the northern side. The lower part of the cut was formed at about 70° and will be supported by a
retaining wall 0.9 m in height, with the upper part of the cutting laid back at 20° (ref. Text Figure 5 above).

The fill batter along the building pad northern edge is formed at about 1V:2H. The fill batter has been re-
surfaced for erosion protection with topsoil and grass cuttings presumably striped from the site prior to cut/fill
operations. We are advised that earthworks were conducted with a Catepillar D6 Dozer, with fill being
entirely sourced from on site cuts and tracked rolled in 200 mm thick layers.

The driveway from Flooded Gum Place is located on the eastern side of the central drainage line and is
formed with relatively minor earthworks less than 1 m in height/depth. At the top of the driveway an
embankment had been formed providing access over the head of the broad central drainage line to the
western part of the site. The fill there appeared to be up to about 2 m in height and was battered at 30° to
35°.




                                                                               Surface depression associated with
                                                                               broad central drainage line




      Ridgeline above southern boundary




Text Figure 6: Image showing ground surface contours (courtesy NC IntraMaps)


General site conditions at the time of the walkover are recorded in Text Figures 7 to 9 on the following
pages.




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