smiths lake planning study volume 1: text - Great Lakes Council

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STORMWATER MANAGEMENT 34 4 STORMWATER MANAGEMENT 4.1 Introduction This section of the report assesses stormwater management requirements for both the SLA and SLVA. The approach taken in regard to this issue, and the findings of our assessments are closely related to the Water Quality Sensitivity Mapping activities discussed in Section 7. In accordance with acceptable and contemporary stormwater management planning practice, this study has not just considered stormwater from a drainage perspective. An holistic viewpoint has been taken, making appropriate stormwater management recommendations based on the consideration of a wide range of issues, including the following: • receiving water environmental and ambient quality characteristics; • catchment characteristics such as slope, soil type and vegetation cover; and • development characteristics, such as urban density and how stormwater infrastructure can be integrated within urban area layouts. In this regard, firstly the receiving environment characteristics of the study catchments are described, and whole of catchment stormwater/pollutant export objectives are specified. Subsequently, relevant stormwater management actions that are recommended to apply across the entire catchment are introduced, and finally additional actions required in areas of specific stormwater related ‘sensitivity’ are discussed. 4.2 Receiving Environment Implications Section 7.2 of this report presents a summary of available water quality data for both Wallis and Smiths Lakes. Other discussion contained in Section 7 introduces the recommendations of this study that there be a ‘no worsening’ criteria applied with respect to non-point source (stormwater) pollutant export. This recommendation is a key influence on the acceptable nature of development and stormwater infrastructure within the SLA and SLVA. 4.3 Whole of Study Area Considerations As described above, both Smiths and Wallis Lakes are sensitive to significant changes in catchment/stormwater pollutant export. The basic reasons for this are: • Smiths Lake is in an almost ‘natural’ condition and has little capacity for assimilating change in catchment loads due to the long retention times of the lake and occasional vertical water column stratification; and • Wallis Lake nutrient levels are already higher than desirable due to other catchment inputs and the poor flushing characteristics of the southern sections of the lake. Given the above, this planning study must aim for a no worsening scenario with future development in terms of total stormwater pollutant export to the lakes. SMITHS_LAKE_PLANNING_STUDY.DOC O C E A N I C S A U S T R A L I A
STORMWATER MANAGEMENT 35 This study aims to achieve this goal via a three-fold approach, as follows: • the development of a range of overall site/catchment drainage planning principles (or Best Planning Practices (BPP’s)); • the development of a ‘suite’ of relevant stormwater Best Management Practices (BMP’s) to be applied in association with the aforementioned BPP’s; and • use of catchment/receiving water quality sensitivity mapping, (Section 7) to identify areas which will require ‘extra’ attention. In this regard, we propose that those areas of low, moderate and high receiving water quality sensitivity identified in Section 7 of this study be directed to apply progressively greater ranges of the aforementioned BPP’s and BMP’s in order to guarantee environmental protection. Figure 4-1 Water Resource Planning Units The above approach is compatible with the Water Sensitive Urban Design (WSUD) approach promulgated in Whelans et. al. (1994). Two figures are reproduced from this reference in Figures 4.1 and 4.2 which illustrate both the proposed approach of using sensitivity mapping to identify appropriate water resources planning units (Figure 4.1) and how BMP’s and BPP’s combine to achieve an appropriate design (Figure 4.2). It should be noted at this point that the study brief called for the conceptual design of four systems including ‘traditional’, ‘non-traditional’ and one based on maximising infiltration. WBM Oceanics Australia see no logical reason for such works as: • a ‘traditional’ design would violate the defined no worsening criteria for pollutant export, and as such is unacceptable; • a ‘non-traditional’ system is what is proposed; and • a system which solely maximises infiltration ignores the wide range of other stormwater management and treatment mechanisms (filtration, detention etc) and is unlikely on its own to achieve the no-worsening criteria. Figure 4-2 Water Sensitive Design Overview SMITHS_LAKE_PLANNING_STUDY.DOC O C E A N I C S A U S T R A L I A
Page 1 and 2: SMITHS LAKE PLANNING STUDY VOLUME 1
Page 3 and 4: CONTENTS I CONTENTS 1 INTRODUCTION
Page 5 and 6: CONTENTS III 11.1 Sewer 128 11.2 Ot
Page 7 and 8: LIST OF FIGURES V Figure 8-1 Visual
Page 9 and 10: INTRODUCTION 1 1 INTRODUCTION 1.1 G
Page 11 and 12: INTRODUCTION 3 • visual quality;
Page 13 and 14: SOILS AND GEOTECHNICAL 5 2.2.2 Fiel
Page 15 and 16: SOILS AND GEOTECHNICAL 7 2.3.3 Geol
Page 17 and 18: SOILS AND GEOTECHNICAL 9 Table 2-3
Page 19 and 20: SOILS AND GEOTECHNICAL 11 rather th
Page 21 and 22: SOILS AND GEOTECHNICAL 13 soils wit
Page 23 and 24: SOILS AND GEOTECHNICAL 15 The resul
Page 25 and 26: SOILS AND GEOTECHNICAL 17 • RCA11
Page 27 and 28: SOILS AND GEOTECHNICAL 19 to steepe
Page 29 and 30: SOILS AND GEOTECHNICAL 21 Based on
Page 31 and 32: SOILS AND GEOTECHNICAL 23 • Mediu
Page 33 and 34: SOILS AND GEOTECHNICAL 25 There are
Page 35 and 36: FLOODING AND DRAINAGE 27 3 FLOODING
Page 37 and 38: FLOODING AND DRAINAGE 29 3.2 Floodi
Page 39 and 40: FLOODING AND DRAINAGE 31 3.2.3 Floo
Page 41: FLOODING AND DRAINAGE 33 the perime
Page 45 and 46: STORMWATER MANAGEMENT 37 Figure 4-4
Page 47 and 48: STORMWATER MANAGEMENT 39 4.4.7 Sedi
Page 49 and 50: STORMWATER MANAGEMENT 41 4.5.4 Swal
Page 51 and 52: STORMWATER MANAGEMENT 43 Table 4-1
Page 53 and 54: FLORA 45 characteristics. Some vege
Page 55 and 56: FLORA 47 mahogany (Eucalyptus robus
Page 57 and 58: FLORA 49 Distribution: This forest
Page 59 and 60: FLORA 51 Distribution: This forest
Page 61 and 62: FLORA 53 5.2.23 Scrub (224) Structu
Page 63 and 64: FLORA 55 Species Significance & Dis
Page 65 and 66: FLORA 57 Species Significance & Dis
Page 67 and 68: FLORA 59 5.4.7 Swamp Oak (32) Distr
Page 69 and 70: FLORA 61 5.4.17 Spotted Gum (70) Di
Page 71 and 72: FLORA 63 Forest Type Description Co
Page 73 and 74: FAUNA 65 6.1.4 Swamp Oak (32) Habit
Page 75 and 76: FAUNA 67 heathland shrub layer woul
Page 77 and 78: FAUNA 69 of the tree adjacent to th
Page 79 and 80: FAUNA 71 Common Name Scientific Nam
Page 81 and 82: FAUNA 73 Common Name Scientific Nam
Page 83 and 84: FAUNA 75 6.4.1.1 Community Habitat
Page 85 and 86: FAUNA 77 6.4.2 Problems with the Me
Page 87 and 88: FAUNA 79 6.6.3 Development of Mediu
Page 89 and 90: WATER QUALITY SENSITIVITY MAPPING 8
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WATER QUALITY SENSITIVITY MAPPING 8
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VISUAL AND SCENIC QUALITY 87 Rural
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VISUAL AND SCENIC QUALITY 89 • mi
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VISUAL AND SCENIC QUALITY 91 8.3.1
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VISUAL AND SCENIC QUALITY 93 Sensit
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LAND CAPABILITY ASSESSMENT 95 9 LAN
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LAND CAPABILITY ASSESSMENT 97 Time
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LAND CAPABILITY ASSESSMENT 99 Envir
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LAND CAPABILITY ASSESSMENT 101 Envi
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ABORIGINAL AND EUROPEAN HERITAGE 10
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INFRASTRUCTURE 129 11.2 Other Servi
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BUSHFIRE MANAGEMENT INVESTIGATION 1
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LAND SUITABILITY ASSESSMENT 139 13
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LAND SUITABILITY ASSESSMENT 141 lin
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LAND SUITABILITY ASSESSMENT 143 13.
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LAND SUITABILITY ASSESSMENT 145 The
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LAND SUITABILITY ASSESSMENT 147 13.
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LAND SUITABILITY ASSESSMENT 149 The
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REFERENCES 151 Floyd, A.G. (1990)
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