Attachment 6 - Stormwater Management Plan

R2015: NOOSA LANDFILL - STORMWATER MANAGEMENT PLAN



4                PROPOSED STORMWATER MANAGEMENT
This Operational Stormwater Management Plan has been prepared to detail proposed control measures and drainage
staging for future masterplanned works on site. For the purpose of this report, the works have been divided into two
main catchments:

       +      Southern Catchment – Proposed Clean water drain and HES basin at the revised SW5 location
       +      Northern Catchment – SW4 and SW2 with the proposed HES basin and drainage augmentation

4.1.                SOUTHERN CATCHMENT (SW5)

Works occurring in the southern catchment include:

       +      Ongoing Cell 2.2 operations
       +      Cell 1.1 Expansion
       +      Southern Clean Water Drain
       +      SW5 HES basin
       +      Construction of Cell 3.2 & 3.3

Detailed design has been undertaken for the Clean Water Drain and HES basin, along with Staging Plans, a Design Report
and a Concept Erosion and Sediment Control Plan for staging of construction works. Refer to Appendix B for the Design
Report which includes details on the staging plans, HES basin sizing and clean water drain sizing, and Appendix C for
the Concept Erosion and Sediment Control Plan for construction works stormwater management.

4.2.                NORTHERN CATCHMENT (SW2 & SW4)

Works occurring in the northern catchment include:

       +      Cell 1.1 Batter Capping Works
       +      Construction of Cell 3.4
       +      Filling of Redevelopment Area for Green waste and Concrete Crushing

Proposed stormwater management strategies for the Cell 1.1 Batter Capping Works are provided in Appendix C in the
Concept Erosion and Sediment Control Plan. Due to the lack of space on the northern capping works, use of the HES
basin would be the preferred management approach, however, this would exceed the design catchment unless the Cell
1.1/2.1 catchment currently grading to the HES basin can be stabilised and diverted prior to works (refer to Section 3.1).

Multiple options exist in regards to augmentation of the existing HES basin in conjunction with filling of the
redevelopment area and construction of Cell 3.4. These options are provided below based on discussions with NSC and
provided in Appendix A:

       1.     Widen Existing HES basin.

The current HES basin outlet is well below flood levels (provided by NSC) in the adjoining drainage channel creating
inflows to the HES basin outlet and limiting discharge from the outlet pipe. This is exacerbated due to a high point in
the downstream drainage channel.




Figure 7 – Existing HES Basin Outlet and Flood Levels

Environment. Engineering. Education.                                                                               PAGE 10