Holroyd to Rookwood Road cable REF - TransGrid

AECOM Transgrid LPCR Transmission LineTransgrid LPCR Transmission LineTransgrid
Cycleway Channel Transmission Line
LPCR - U/G Transmission Line - Potential Construction Impacts
1.0 Purpose of Report
The purpose of this report is to comment on the likely effects of construction operations during the installation of
Transgrid’s underground electrical transmission line parallel, and adjacent to, the Lower Prospect Canal Reserve
(LPCR). The underground transmission line will be located immediately adjacent to the LPCR cycleway channel
which is a heritage listed item. It is believed that Transgrid will use this report as the basis for discussion with the
successful Contractor to better understand his approach to minimising impacts on the channel.
2.0 Background
The LPCR traverses through a densely populated area of Western Sydney. The corridor stretches for
approximately 7.7 kilometres from Prospect Reservoir to Sydney Water Pipehead at Albert Street, Guildford and
varies in width from 40 metres to 100 metres covering an area of approximately 54.6 hectares
The channel within the LPCR was built in 1880 from sandstone masonry. Between 1907 and 1912 it was relined
with pre-cast concrete “Monier Plates”. The relining raised the height of the canal walls and thus increased the
capacity from a total volume of 395ML to 450ML.
The canal ceased to be a conveyance of water in 1995. In 2001 work commenced on filling the canal and
converting the corridor into a public space. August 2003 saw the reserve opened to the community with a
cycleway / walkway running its full length.
Transgrid representative Paul Henry met with the author on Monday 24 October 2011 to “walk the site” and
describe the features of the canal and the anticipated construction method likely to be employed during project
execution. It is understood that the construction phase of project is currently at tender at the time of writing of this
report.
3.0 Referenced Documents
The following documents were referenced in this desktop assessment:
Lower Prospect Canal Reserve – Canal Reserve Action Group. Untitled. Accessed at:
http://www.canalreserve.org/reserve/reserve.html. Appendix A.
Historical signage erected along the canal walk. Refer photos Appendix A.
Geotechnical “pressure bulb” diagrams supplied by Douglas Partners. Appendix C.
Komatsu PC220 / PC220LC excavator specifications. Appendix D.
4.0 Observations
4.1 Canal
Visual remnants of the canal are clearly evident. During the inspection the following were noted:
The canal is approximately 7.7km long and has follows a general alignment of SE to NW,
Precast concrete “Monier Plates” protrude from the earth to a height of approximately 0.3m above
finished surface level,
Precast concrete thrust blocks approximately 0.25m x 0.4m at 1.2m centres are placed behind the
“Monier Plates”,
At many locations the “Monier Plates” have rotated forward from the thrust blocks presumably as a result
of unbalanced earth pressure. This would not have been an issue duration operation of the channel as
hydrostatic water pressure would have counter-acted this effect,
The canal has been filled to a level approximately 0.3m beneath the height of the “Monier Plates”,
\\ausyd1fp001\Projects\60157132_TG_330kV_Cable\6. Draft docs\6.1. Reports\Heritage Culvert Transgrid Implications
Report.docxC:\Mark F Files\Projects\Holroyd to Rookwood\Cycleway Channel\Transgrid Implications Report.docx
Revision 01 - 26 October 2011
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