Attachment E - Secondary Dwelling (Exisitng Dwelling Plans from BA) · MCU22/0135

The sample hand collected and classified on site from BH 1 at a depth of 800 mm
below the existing surface level returned a linear shrinkage result of 10.6%.

The expected surface movement (Ys), due to seasonal moisture changes in the soil
encountered, is as follows

 

 

Ys Value = 27 mm

 

 

Predicted Surface Movement

Ys=<20 mm

Ys => 40-< 60 mm Hl
Ys => 60-<s 75 mm H2
Ys=>75 mm E
Problem sites P

 

Note: With a full depth clay profile the Ys value would increase to 30 mm.

Note: Our assessment does not consider the effect of the presence of trees within or
adjacent to the building site, nor the removal of trees prior to or after construction, nor
the growth of trees too close to the footings. The proximity of trees and their effect on
foundations should be considered when determining specific engineering assessments,
and for foundation/footing design. Appendix B of AS 2870-2011 indicates that to reduce,
but not eliminate, the possibility of damage to the footings, trees should be restricted to
the following distance from the building (where rows or groups of trees are present the
distance nominated below must be increased, and similarly the Ys Value listed above may
need to be increased) : 75% of the mature tree height, for class “M” sites, 100% of the
mature tree height, for class “H 1” sites, and 150% of the mature tree height, for
class “E” sites.

Note: This classification above has been derived from test work performed on the soil
profile encountered on the day of our fieldwork. Any filling of the site or excavation
into the soil profile, of 300mm may result in a different classification.

Temporary Excavations.

Where temporary excavations are performed for footing or services up to 600mm
deep, natural soils may have minor or no stability problems, however deeper
excavations have a possibility of collapse more readily and shoring of vertical
excavation may be required. Where an existing excavation has been filled with
uncontrolled fill, all locations above a line 30 degrees for sands and 45 degrees for
clays above the horizontal may be unstable and may not support any structure — see
attached critical depth line diagram.

Existing Services.
We were not informed of any existing service line excavations and no existing service
line excavations were identified within or immediately adjacent to the proposed house

site.

 

Unearthed Geotechnical P/L. 4 Site Investigation Report 019-090