ordinary meeting of council to be held on tuesday, 26 april 2005 at ...

Ordinary Meeting <strong>of</strong> Council - 26 April 2005 19 / 31
2 <strong>to</strong> 4A Finlay Road, Turramurra
Item 19
DA1270/04
6 April 2005
The Tree Protection Zone Plan (UTM Appendix A Site Plan B) does not appear <strong>to</strong> <strong>be</strong>
consistent with either the concept s<strong>to</strong>rmwater management plan or the environmental
site management plan (Dincel & Associates 04060-C02/A) in relation <strong>to</strong> material
s<strong>to</strong>ckpile and waste bin locations.
Council’s Landscape Officer has commented on the lack <strong>of</strong> concept design information
in relation <strong>to</strong> the proposed interallotment drainage line through the downstream
properties. The two pipes leading <strong>to</strong> pit P9 are 225mm and 300mm diameter. Given
the likely size <strong>of</strong> the pipe and the presence <strong>of</strong> large trees along the line <strong>of</strong> the proposed
easement, hand excavation is not likely <strong>to</strong> <strong>be</strong> practicable here.
Flooding and overland flow comments
The site itself does not appear <strong>to</strong> <strong>be</strong> subject <strong>to</strong> overland flow, although seepage and
dampness due <strong>to</strong> the steep slope is noted within No. 4A. A depression runs downstream
through 4B Finlay Road (dry upon inspection on 1 March). At present this appears <strong>to</strong>
<strong>be</strong> conveying some run<strong>of</strong>f from hard surfaces <strong>of</strong> the upstream property. Natural areas
will continue <strong>to</strong> drain in<strong>to</strong> this depression during times <strong>of</strong> rain. The dwelling at 4B is
well above ground level and there would not appear <strong>to</strong> <strong>be</strong> any associated overland flow
issues.
Geotechnical/structural comments
A geotechnical investigation, comprising two cored boreholes, has <strong>be</strong>en carried out by
Geotechnique. One <strong>of</strong> the boreholes was terminated at RL170.4, that is some 9 metres
above the lowest basement level, and without confirming the depth <strong>to</strong> Class III shale.
The site is underlain by about 6 <strong>to</strong> 9 metres <strong>of</strong> hard clay.
The basement excavation along the north, east and western frontages will not <strong>be</strong> able <strong>to</strong>
<strong>be</strong> battered <strong>to</strong> the recommended slopes <strong>be</strong>cause <strong>of</strong> the small setbacks and the Tree
Protection Zones, so it is expected that soldier piles as recommended will <strong>be</strong> adopted.
This means that anchors will extend <strong>be</strong>neath the road, <strong>be</strong>neath 1458 Pacific Highway
and <strong>be</strong>neath 1456a Pacific Highway.
The approval <strong>of</strong> the relevant property owners will <strong>be</strong> required <strong>be</strong>fore proceeding, as
identified in the Geotechnique report. Since 1456a Pacific Highway is also subject <strong>to</strong> a
2(d3) zoning, the proposed rock anchors may conflict with future development
proposals for that site. This will <strong>be</strong> a matter for the owners <strong>to</strong> resolve, so if an
alternative means <strong>of</strong> excavation support is likely <strong>to</strong> <strong>be</strong> required, it should <strong>be</strong> identified
in the supplementary geotechnical report.
With regard <strong>to</strong> Finlay Road, Council will not approve the use <strong>of</strong> permanent rock
anchors, and approval under the Roads Act will <strong>be</strong> required for temporary anchors
under the road reserve. Conditions will <strong>be</strong> imposed including de-stressing <strong>of</strong> the
anchors after completion and the provision <strong>of</strong> permanent warning signs on the building.
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