Stormwater Management Plan

GOOD SHEPHERD LUTHERAN COLLEGE                                                                   ODYSSEY CONSULTING GROUP
Lot 30 on SP170751                                                                    Conceptual Stormwater Management Plan
115 Eumundi Noosa Road, Noosaville                                                                          Project No: K4277

         The following sections describe the predicted increase in pollutant loads generated by the proposed
         development and treatment devices to mitigate the potential increases. In accordance with industry
         guidelines suspended solids, nitrogen and phosphorus will be targeted for reduction during the
         operational phase of the development.

5.2      Water Quality Objectives
         To protect the water quality of the downstream watercourses the following water quality objective
         has been applied to stormwater runoff from the site in accordance with State Planning Policy. The
         following load reduction targets must be achieved when assessing the post-developed sites treatment
         train (comparison of unmitigated developed case versus developed mitigated case):
                 80% reduction in Total Suspended Sediment (TSS);
                 45% reduction in Total Nitrogen (TN);
                 60% reduction in Total Phosphorus (TP); and
                 90% reduction in litter (sized 5 mm or greater)

5.3      Construction Phase
         A high risk of stormwater pollution will occur from the site during the construction phase due to
         erosion and sediment transportation off site to the receiving environment. The majority of this risk
         results from construction activities disturbing the site and exposing areas of soil to the direct erosive
         influence of the environment. The following section outlines the procedures necessary to minimise
         erosion and control sediment during construction in accordance with Department of Environment and
         Resource Management’s, Urban Stormwater Quality Planning Guidelines, 2010, (DERM USQG). and
         the Institution of Engineers Australia (QLD) Erosion and Sediment Control Guidelines.

5.3.1 Common Pollutants
         In accordance with Table 1.1 (DERM USQG, 2010) the following common pollutants have been
         identified for the Construction Phase of this development.

         Table 16:        Construction Phase Key Pollutants
             Pollutant                  Sources
             Litter                     Paper, construction packaging, food packaging, cement bags, material off cuts.
             Sediment                   Exposed soils and stockpiles during earthworks and building works.
                                        Fuel and oil spills, leaks from construction equipment and temporary car park
             Hydrocarbons
                                        areas.
                                        Cement slurry, asphalt primer, solvents, cleaning agents, and wash waters (e.g.,
             Toxic Materials
                                        from tile works).
             Acids of Alkaline
                                        Acid sulphate soil, cement slurry and wash waters.
             Substances

5.3.2 Performance Criteria
         The following site discharge pollutant criteria have been adopted for water quality monitoring during
         the construction phase of the development.

         Table 17:        Construction Phase Water Quality Performance Criteria
             Pollutant                  Criteria
             Total Suspended Solids     90th percentile <50mg/L
             pH                         6.5 – 8.5
             Dissolved Oxygen           90th percentile >80% saturation or 6mg/L
             Hydrocarbons               No visible sheen on receiving waters
             Litter                     No visible litter washed from site.
                                        As recommended by Acid Sulphate Soil Management Plan (If
             Cations and Anions
                                        Applicable to Development).




K4277-0002-D                                           14 February 2019                                         Page 10 of 16