Further information re Request to Change Approval MCU 132003.221132.8

STORMWATER QUALITY MANAGEMENT DESIGN AND ASSESSMENTS                                                                            2-1



2            STORMWATER QUALITY MANAGEMENT DESIGN AND
             ASSESSMENTS

2.1          Stormwater Management Objectives

              In the approved Doonella Noosa Storm water and Water Quality Management Plan (WBM,2005),

             Section 2.1, the stormwater quality objectives were stated as:

                    No increase in total suspended solids, total nitrogen or total phosphorus loads to Lake Doonella

                    from the existing case, which is defined as bushland; and

             .      Acceptable loads of other pollutants e.g. litter, in accordance with relevant guidelines.

             These objectives were based on assessment of historical water quality within Lake Doonella. The

             review identified that Lake Doonella had limited capacity to absorb additional pollutant loadings from

             the catchment, although detailed receiving water quality modelling was never completed which would

             be able to more accurately define the potential effects of increased catchment loadings.                         Further

             specific proposed concentration based objectives were provided in Table 2-1 (of the approved
             report), based on earlier Brisbane City Council guidelines.

             It should be noted that at the time this work was completed, the then Noosa Shire Council had no

             specific guidance               available   to   developers   to   allow   them   to   determine   suitable   stormwater

             management targets, hence objectives were established by BMT WBM (formerly WBM) based on a
             review of existing site and receiving water data, and available guidelines, such as the Brisbane City

             Council guidelines.


             The no-net-increase              objectives were assessed in the approved Doonella Noosa Stormwater and
              Water     Quality Management Plan (WBM, 2005).                     It was found at that stage the no-net-increase

             objective was difficult to achieve across the Doonella Noosa development, as the modelled results for
             nutrients were observed to fall a few percent short of their target (see Table 2-9 to 2-13 of that report).

             Despite these minor shortcomings, the approach was acceptable to Council (and its third party
             reviewers).


             Since this time, there have been significant changes in the legislative framework. In 2010, the State

             Planning Policy (SPP)for Healthy Waters was enacted. This document sets out State-wide targets
             for water quality and quantity management based on current best practice management and local

             climatic factors.


             For the Sunshine Coast Region                    (incorporating Noosa), the relevant objectives are outlined in the
             Urban Stormwater                Quality Planning Guidelines (DERM, 2010).              These   guidelines assist in the
             application of the SPP for Healthy Waters.                  Based on relevant stormwater quality targets for South

             East Queensland            (which incorporates the Sunshine Coast             Regional Council), the following load
             based targets are applicable:

             .      TSS      -
                                 80%;

             .      TP   -
                             60%;

             .      TN   -
                             45%; and




G:IADMINIB 15573.G.BADIR.B15573.002.00.DOC
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