Development Application Part 2 - Environmental & Stormwater Management Plans · OPW11/0335

3.         LOCAL ENVIRONMENT

The site, surrounding land use, existing topography and stormwater flow direction were
described in the conceptual Stormwater Management Plan (Simmonds and Bristow, 2009)

The receiving environment for stormwater runoff is remnant native wet-heath vegetation that
grows along the western boundary as an extension of the Noosa National Park (Natural
Solutions, 2007). For this development it was proposed at the Joint Experts Conference that
the long term median water quality targets for stormwater entering the receiving environment
should be the values listed in Table 1. These long term targets do not apply to individual
measurements from runoff events, or to construction phase monitoring. The low pH target for
stormwater reflects the naturally low pH character of the wallum/tannin stained receiving waters.




                                             Table 1: Water Quality Objectives
 Indicator                                                          Water Quality Objectives
 Suspended Solids                                                   15 mg/ L

 Total Phosphorus                                                   35 pg/L
 Total Nitrogen                                                     350 pg/L

 pH                                                                 5-7


These outcomes can also be compared with the Water Quality Objectives for loads reductions
required by the Queensland Water Quality Guidelines (DERM 2009)(Table 2). The loads
reductions water quality design objectives are important because stormwater flow is
intermittent, with most export of sediment and nutrients occurring during a few short rainfall
events each year. Management needs to cover those few rainfall events, and design objectives
for annual load reductions need to accommodate for high stormwater-flow events.



                          Table 2: Water Quality Design Objectives for Loads Reductions
 Indicator                                                          Water Quality Objectives

 Suspended Solids                                                   80% reduction
 Total Phosphorus                                                   60 % reduction
 Total Nitrogen                                                   145 % reduction




02011 Simmonds & Bristow Pty Ltd              Pacific Plumbing - Scanlon Property Group Pty Ltd                      J-1109-155 - 8 September 2011
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