Attachment 6 - Stormwater Management Plan

R1890: NOOSA LANDFILL EXPANSION – CONCEPT ESCP



3                CONCEPTUAL STORMWATER STRATEGY
A conceptual strategy for each works areas is provided in Appendix A. The strategy adopted by the Principal Contractor
for the works may differ due to the proposed staging or construction methodology.

A summary of the conceptual strategy is provided below for each section of works:

       1.     Cell 1.1 & 2.2 Expansion – The bulk of works are in cut, so as works progress the areas will be self contained.
              During early works prior to significant excavation, the outer ends of the works are to be bunded to contain
              runoff.

       2.     Perimeter Road – The perimeter road is predominantly in fill. As fill is raised with the perimeter road, runoff can
              be directed into the excavation for the Cell 1.1 & 2.2 Expansion or into the excavation with the Clean Water Drain.
              Any batters that are outside of the holding areas should be progressively stabilised as fill is raised through the
              use of permanent measures or temporary measures such as soil binder.

       3.     Clean Water Drain – The drain is predominantly in cut. As works progress the downstream end can be left high
              so all runoff is contained within the excavation. It is not likely to be practical to divert external runoff away from
              the drain, so all runoff will be required to be captured within the work zone. As works progress to the
              downstream end of works where runoff cannot be contained, works are to be staged and rapidly stabilised
              prior to rainfall through the use of temporary or permanent measures.

       4.     Sediment Basin – The sediment basin is all in cut. As stripping occurs a perimeter bund can be placed around
              works prior to excavation occurring to self contain all runoff within the works area.

       5.     Capping Works (Southern Batter) – Dams are located along the toe of the southern batter. It is unclear if these
              dams have sufficient capacity to contain the required design event as a temporary sediment basin, however, if
              suitable could be utilised.

       6.     Capping Works (Western Batter) – The western batter can be directed to the existing High-Efficiency Sediment
              basin in consultation with the superintendent. Temporary drainage will be required to ensure runoff is directed
              to the basin.

3.1.                USE OF EXISTING DAMS / HES BASIN

The use of existing dams on site is to be requested and approved by NSC prior to works. The Principal Contractor and
NSC will agree on the following:

       +      Final state of dams – will clean out and treatment be required prior to project completion
       +      Agreed pump and dewatering locations to and from the holding dams
       +      Approved coagulant / flocculant product

The use of the existing HES basin on site is also to be requested and approved by NSC prior to capping works. The
Principal Contractor and NSC will agree on the following:

       +      Final state of basin – will clean out and treatment be required prior to project completion
       +      Agreed pump and dewatering locations to the HES basin
       +      Agreed catchment and/or flow rates to the basin
       +      Cost of operation / coagulant




Environment. Engineering. Education.                                                                                        PAGE 4