Appendix B - Geotechnical Investigation Report

The bulk excavations must be carefully completed and prior to the excavations commencing the overgrown
rock wall should be cleared of vegetation and inspected by the structural and geotechnical engineers in order
to assess the current condition of the wall. In addition, if the rock wall extends across the site boundary,
then the inspection will assist in confirming the most appropriate excavation strategy in order to maintain
stability of the portion of wall that will remain, including any temporary propping or permanent stabilisation
measures, if applicable.

Based on the ASI investigation results, the proposed excavations will encounter the soil profile. Any topsoil
or root affected soils should be stripped and separately stockpiled for re-use in landscape areas or
appropriately disposed of off site.

Due to the small size and sloping nature of the central portion of the site, we expect the excavations will be
completed using small to medium sized tracked excavators, and excavation of the soils and any sections of
the overgrown rock wall will be readily completed with buckets of such equipment. Locally a ripping tyne
attachment to the excavator may be required over the deepest section of the excavation in order to remove
weathered rock. If rock breakers are required then further advice will need to be sought as potentially
damaging vibrations can be generated by rock breakers.

The poorly compacted surficial fill encountered in the investigation may extend across the site boundaries.
We therefore advise that sudden stop/start movements of any tracked equipment should be avoided in order
to reduce transmission of ground vibrations to the adjacent sections of buildings and structures within and
neighbouring the site.



6.3.3 Seepage
Groundwater seepage was not encountered in the boreholes completed by ASI. Some ephemeral seepage
inflows may be encountered in any excavations particularly after periods of heavy or prolonged rainfall. In
general, we expect that inflows, if any, to be of very small volume and managed by gravity drainage to the
lower gently sloping portion of the site. Inspection and monitoring of groundwater seepage during
excavations is recommended, so that any unexpected conditions, which may be revealed can be incorporated
into the drainage design.



6.4   Temporary Excavation Support and Retention
Temporary batter slopes through the sandy soil profile no steeper than 1 Vertical (V) in 1.5 Horizontal (H) are
considered to be appropriate, steeper batters of 1V in 1H will be suitable for clay soils and any extremely
weathered bedrock (if encountered), though some surficial instability could still occur. These temporary
batters are expected to be achievable within the site geometry.

Some instability of temporary sand batters may occur at, or below, the level of any groundwater seepage
should it occur, especially after rain periods, and sand bagging may be required to stabilise the lower portion
of these batters.


35891URrpt Rev1                                    9