Attachment 6 - Stormwater Management Plan

R2015: NOOSA LANDFILL - STORMWATER MANAGEMENT PLAN



3                EXISTING STORMWATER MANAGEMENT
Based on discussion with site personnel, the site currently operates in the following manner:

       1.     Southern Catchment (SW5) – minimal disturbance and no sediment control prior to release (operating as a
              stable catchment)
       2.     Cell 2.2 (active cell) – Captured in-situ and directed to Leachate system
       3.     Northern Catchment:
                   a. Portion directed to HES basin
                   b. Portion directed to Bio Basin (Green Waste)
                   c. Portion directed off-site as clean water

For further details relating to the existing drainage refer to Figure 6 and Appendix A.




Figure 6 – Existing Drainage Regime

3.1.                RECOMMENDATIONS FOR CURRENT STORMWATER MANAGEMENT

The HES basin was designed in 2010 by Opus for a catchment size of 3.6 hectares. The current catchment that is estimated
to be draining to the basin is 3.9 hectares being within 10% of the design catchment. It is recommended that monitoring
is undertaken on the basin to ensure adequate performance with the current catchment draining to the basin.

Two assumptions have been made in relation to the catchment draining to the HES basin:

       1.     A pipe from Cell 1.1 is blocked to limit inflows to the HES basin. This was a recommendation from the 2013 O2
              Report to be implemented once the catchment was stabilised (it is currently grassed). Some drainage
              augmentation may be required to ensure the drain can flow to the desired clean water culvert. Refer to
              Appendix A, Drawing Concept-09 for details
       2.     Stabilise the portion of the Existing landfill Cell 1.1/2.1 currently grading to the HES basin and divert the flows to
              SW4 once stable. Refer to Appendix A, Drawing Concept-01 for catchment details and Concept-09 and
              Concept-10 for flow paths. This will reduce the catchment to HES basin below the design catchment.

In addition to augmenting drainage, any catchments that are outside of those being directed to the HES basin or bio-
basin should be operating on a capture or erosion control (stabilisation) strategy. It is also recommended that a frog flap
be investigated for the outlet of the pipe from the HES basin due to flood levels.


Environment. Engineering. Education.                                                                                        PAGE 9