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

6.         SEDIMENT AND EROSION CONTROL PLAN

The Noosa River: Environmental Values and Water Quality Objectives state that the
environmental values associated with the Noosa River Wetlands include aquatic ecosystem
protection, and cultural and spiritual values. Because Noosa National Park is a protected area,
these values require a high level of protection (level 1 protection).

During the construction of the Essence of Peregian Stage 1 development, there is a hazard that
disturbed soil might be carried into the wetland by stormwater.       Mobilisation of stockpiled
sediment is of particular concern, but this hazard can be easily managed. In particular, fine
sediment mobilised by stormwater will potentially carry nutrients into the wetland.   The likely
consequence of this is increased nutrient availability to weeds, with potential negative
consequences for the adjacent Noosa National Park ecosystem.

Assessment of the Queensland Best Practice Environmental Management Guidelines (DERM,
2009) checklist (Table 5), shows that overall there is a high erosion hazard for this site. This
hazard is directly affected by soil type (particularly imported fill on lower slopes), the need to
reshape the ground surface to construct structures, and the anticipated duration of site
disturbance being 3 to 6 months. The hazard is greater during the wet season between
November and July when the average monthly rainfall is expected to be above 100 mm.

                                  Table 5: Factors Contributing to Erosion Hazard
                                                Erosion Hazard Assessment Form
 Controlling Factor                                                                  Points                       Score
 Average Slope of Whole Site                                                         1                            1
 Soil type being disturbed                                                           2 or 5                       3 or 6
 Anticipated duration of site disturbance                                            5                            8 or 11
 Erosive rainfall risk during site disturbance                                      1 between Aug -               9 or up to 13
                                                                                    Oct; 2 between Nov
                                                                                    - Jul.
 Off-site sediment control (downslope of soil disturbance)                          0                             9 or up to 13
 Run-off entering the site                                                          0                             9 or up to 13
 Extent of site disturbance                                                          2                            11 or up to 15

 Total Score                                                                         11 -15                       High Erosion Risk


By implementing sediment and erosion controls, it is possible to moderate the erosion hazard.
This includes protective covering of disturbed soils (particularly on erosion prone parts of the
landscape, and when rain is expected), promptly revegetating soil that is planned to be
stockpiled in the Stage 2 area (in anticipation of future development), scheduling work to avoid
the highest rainfall risk period, installing upslope diversion of runoff away from soil disturbance,
and installing purpose built sediment control traps down-slope of the soil disturbance.

The SECP has identified construction site best practices for managing sediment erosion and
control. A daily site check-list will be used to ensure that building contractors are cognizant of
and performing the required management actions. This check-list is attached in Appendix C.
The SECP also coordinates stormwater management with construction milestones, for effective
implementation of sediment erosion and control measures during the construction phase.

The plan layout of the SECP in the proposed development area is shown in Drawing J-1005-
310-08 (Appendix E), which shows where erosion management structures need to be placed
during construction activities. Slope-related erosion hazard areas within the development site
were identified from the topographic map (Drawing J-1005-310-09 in Appendix E), and
represent control points within the construction site where particular care will be needed. The
management actions for controlling erosion of the site, and movement of sediment and nutrients
from the site, are described in Table 6. The detail management plans for sediment and erosion
control are described in Appendix E.


02011 Simmonds & Bristow Pty Ltd                Pacific PlumbNng - Scanlon Property Group Ply Ltd                      J-1109-155 - 8 September 2011
19CLIENTFILESIContrasl Conslruclions11109.155c - Essence of Peregran SCEP Stage I UpdaIef09_Outpul Documen1sU.t109-155c_SMP_Scanlon Property
Group_SECP_ge_u_110905AOC                                                                                                             Page 9 of 21