Storm Water management plan · MCU12/0133.03

Noosa Council documents


                  Bligh Tanner Consulting Engineers                                                                 Page 7
                  Noosa Flexi Learning Centre Stormwater Management Plan
                  August 2012



                  The most appropriate acceptable solution for this site is to have rainwater tanks, sized at
                  1500L per required pedestal (Acceptable Solution A3), which is connected to each required
                  pedestal, external use, and washing machine cold water taps (Acceptable Solution A2).


                  2.4 Construction Phase Objectives
                  Stormwater run-off from land development and infrastructure development sites has a high
                  potential to cause water contamination and/or environmental harm. This is regulated under
                  the EP Act 1994.

                  Under S440ZG it is an offence to unlawfully deposit a prescribed water contaminant to
                  waters. Prescribed contaminants are listed in Schedule 9 of the Environmental Protection
                  Regulation 2008 (EP Reg), and include: ashes, clay, gravel, sediment, stones and similar
                  organic or inorganic matter, as well as building and construction materials and waste.

                  Under S 319 persons in Queensland carrying out activities which may cause environmental
                  harm must comply with the ’general environmental duty’ (GED). This requires that all
                  reasonable and practicable measures must be adopted to prevent and minimise
                  environmental harm. Although not being able to demonstrate compliance against GED is not
                  an offence, demonstrating that all reasonable and practicable measures have been adopted
                  is a defence for offences such as water contamination. For instance, under chapter 10,
                  s493A of the EP Act, where a person deposits a prescribed water contaminant to waters or
                  causes unlawful environmental harm, it is a defence to demonstrate compliance with the
                  GED. Demonstrating that all reasonable and practicable measures have been conceived and
                  implemented should encompass:
                      • thorough and ongoing site assessments
                      • consideration of, and adaptation for site specific erosion risk factors including
                          topography, soil type, climate and season
                      • design, installation, operation, management, maintenance and monitoring of control
                          measures as identified in the erosion and sediment control plan.

                  Erosion Hazard Assessment
                  This site is considered low risk based on the following erosion hazard assessment:
                     • Predicted Annual Soil loss (tonnes) = A x B x T
                     • Where A = R.K.LS.C.P (as per the Revised Universal Soil Loss Equation).

                  Table 4 Values used in erosion hazard estimation
                  Factor    Description                  Adopted value
                  R         Rainfall erosivity factor    5700 (i 2y 6hr = 15.8 mm/hr)
                  K         Soil erodibility factor      0.04 (loam)
                  LS        Topographic factor           0.2 (100 m @ 1%)
                  C         Cover and management         1 (no cover)
                  P         Practice                     1.3 (no management)
                  B         Area of disturbance          0.5 ha
                  T         Predicted duration           0.5 yrs

                  Predicted unmitigated soil loss = 59 t/ha/yr x 0.5 ha x 0.5 yrs = 15 tonnes

                  As this is significantly less than 150 tonnes, this development is considered low risk,
                  and accordingly a minor erosion and sediment control plan will be provided as part of
                  the operational works application, as per Sunshine Coast Regional Council’s Manual
                  for Erosion and Sediment Control V1.2 (Nov 2008).




                                                                                                Print Date: 2 March 2020, 2:19 PM