Attachment 8 - Interim Stormwater Management Plan - TOPO · 132005.638.06

R5304: NOOSA RESOURCE RECOVERY CENTRE - STORMWATER MANAGEMENT PLAN




                                              Figure 3 – Average monthly rainfall for Tewantin

2.3.             TOPOGRAPHY

The topography varies considerably across the site due to historic landfilling operations. The peak elevations occur in
the central portion of the site at ~40.5 m AHD. A central ridgeline through the completed cells directs a large portion of
site runoff to existing drainage features that convey runoff in a northerly direction, either to the site discharge point for
clean water catchments or to the existing HES basin for runoff from high erosion risk areas. All runoff from site is directed
to the northern and north-eastern boundary to discharge points SW2, SW4 and SW5. Details on the existing catchments
and flowpaths are provided in Appendix A with further details provided in Section 3.

A digital terrain model (DTM) of the site was developed from the 2023 LiDAR survey (1 m grid, GDA94 MGA Zone 56)
and interrogated to characterise site grades and the directions of fall.

Site slopes are highly variable with the cell batters ranging between 1:4 (Vertical to Horizontal) to 1:6. The hardstand
areas in the northern portion of the site are considerably flatter, typically less than 2 %. Levels across the site range from
approximately 12.5 m AHD along the northern boundary to approximately 40.5 m AHD at the peak of the completed
cells,(Cell 1.1), falling towards existing drainage features that convey runoff to discharge points at elevations ranging
between 12 to 16 m AHD.

An existing site drainage and catchment plan is presented in Section 3.




Environment. Engineering. Education.                                                                                  PAGE 7