2 David Low Way - Attachment 3 - Civil Engineering Assessment - Sheehy 10-8-17

2.4      Cycleways

There are existing on road cycleways on David Low Way that pass the proposed development
site. This cycleway provision will be maintained and incorporated in the revised access layout
proposed in order to maintain safe provision for cyclists on David Low Way.

It is proposed that existing 1.5m pedestrian pathway on the eastern verge of David Low Way
will be maintained and realigned as necessary to suit the proposed development access layout
as required by the Detached Driveways Code, with pathway ramps provided at the new
crossing location. The pathway will be adjusted as necessary to comply with Noosa Council
Standards for width, vertical alignment and driveway crossings to meet safety requirements.

A Typical Layout proposed is shown on the Conceptual Access Arrangement Plan No.
17BRT0208-01 included in Appendix D.


2.5      Stormwater Drainage

The Proposed Development Site Area contours indicate a number of stormwater catchments
that discharge either to the east or to the north and the existing road reserve. It is anticipated
that all catchments may require both detentioning (to alleviate any increase in flows resulting
from development) and water quality treatment (to meet Noosa Councils water quality
objectives). The development proposal will need to lodge a Site-Specific Stormwater
Management Plan to detail the final methodology proposed to mitigate the impacts of the
specific development. Indicative detentioning and water quality systems have been identified
and are included in a separate report by Cardno. The report has identified a total of
approximately 70m2 of detention basin (approximately 21m3) being required and
accommodated proportionately within each of the building allotments to ensure that there was
no increase in peak rate of runoff from the site following development. Similarly, water quality
management would require an area of approximately 30m2 to be accommodated within each
of the allotments. Each of the proposed allotments is of sufficient size to accommodate these
requirements.
It is considered that due to the nature of the underlaying sand dune a significant reduction in
overland flow will occur from natural infiltration of water. The proposed mitigation measures
will comply with the Earthworks Code and the Transport, Roads and Drainage Code for
planning and design including stormwater capture and treatment. The separation of runoff
from the external site areas and roof water that do not require water quality treatment and the
internally generated water that will need to be captured and treated will be addressed to comply
with the above codes as details in Appendix G.
Regional flooding within the area is a result of inundation from the catchments associated with
a Burgess Creek to the north of the development and from storm / high tide activity. This
flooding does not impact directly on the site.

No Local flooding has been identified within the site, although stormwater runoff directly from
David Low Way generally falls towards the proposed development site. Mitigation works to
collect and manage these overland flows may be required within the road reserve to discharge
them to the Burgees Creek which forms the existing major outfall. The existing table drain
within the road reserve that fronts the property will be adjusted to suit the revised access layout
including the provision of a culvert crossing under the driveway as indicated on the General
Layout and Services Plan included in Appendix B. Overland flow provision will be in
accordance with Council’s Planning Scheme policies, as part of the proposed development.


Document No. 8531 Castaways Development-Rev C   Page 6                            Issue Date: 08/08/2017