Detailed Stormwater Management Practice Design - Tauranga City ...

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SMG-9.4.1.3 Flows in Excess of the 2-year 1-hour Storm It is expected that runoff from events larger than the design storm will go through the swale. In that situation, a stability check should be performed to ensure that the 10year, 1-hour storm does not cause erosion. For the 10-year storm, flow velocities should not exceed 1.5 m/s, although higher velocities may be designed for with appropriate erosion protection. When considering larger storms consideration must be given to increased rainfall values as a result of climate change. SMG-9.4.1.4 Shallow Slope Situations Where slopes are less than 2%, an underdrain must be used to prevent soils from becoming saturated during wet times of the year. SMG-9 Figure 4 Swale Schematic showing Soils and Underdrain provides a typical cross-section of the underdrain system ensuring that water passes through the invert of the swale, through a loam soil, then geotextile fabric and gravel prior to discharge through a 100 mm perforated pipe. Using an underdrain can be one method to meet extended detention requirements. In this case, the extended detention volume can pass through the permeable soil with an assumption of total drainage time being 24 hour SMG-9 Figure 4 - Swale Schematic Showing Soils and Underdrain Page 12 Updated 01/11/2012
SMG-9.4.1.5 Vegetation For the most part, vegetation will consist of either perennial rye or fescue grass. There may be other forms of vegetation that would provide comparable or improved treatment effectiveness with less maintenance requirements. One type of grass is Oioi (Apodasmia similis) that is a very dense grass that grows by rhizome and can become a thick filter media that does not require mowing. SMG-9 Figure 5 Oioi Vegetation Placement shows an Oioi swale at the Auckland Botanic Gardens to promote metals uptake whilst having a reduced maintenance requirement. SMG-9 Figure 5 - Oioi Vegetation Placement (Auckland Botanic Gardens) Page 13 Updated 01/11/2012
Page 1: SMG-9 - Detailed Stormwater Managem
Page 4 and 5: In the same regard reducing total s
Page 6 and 7: As an example, a stormwater managem
Page 8 and 9: SMG-9 Table 2 Stormwater Management
Page 10 and 11: The following points require some d
Page 12 and 13: e) Select a swale shape. Two shapes
Page 16 and 17: SMG-9.4.1.6 Swale Case Study Refer
Page 18 and 19: SMG-9.4.2.1 Basic Design Parameters
Page 20 and 21: ) Once the peak discharge is determ
Page 24 and 25: SMG-9 Figure 11 - Diversion Weir SM
Page 26 and 27: tf = time required for runoff to pa
Page 28 and 29: c) Infiltration (depending on soils
Page 30 and 31: Rain Garden design differs only sli
Page 32 and 33: SMG-9.4.4.1.1 Filter Media Filter m
Page 34 and 35: SMG-9.4.4.1.5 Transition Layer The
Page 36 and 37: SMG-9 Table 11 Grasses, Ground Cove
Page 38 and 39: Infiltration practices are used for
Page 40 and 41: SMG-9 Figure 19 Schematic of a Soak
Page 42 and 43: Any impermeable soil layer close to
Page 46 and 47: SMG-9 Figure 21 Soil Textural Trian
Page 48 and 49: e) Calculate the practice depth and
Page 50 and 51: SMG-9.4.6.1 Types of Pond Ponds are
Page 52 and 53: A study in the U.S.A (DNR. 1986) in
Page 54 and 55: Where there are downstream flooding
Page 56 and 57: There may be mitigation requirement
Page 58 and 59: SMG-9.4.6.12 Pond Aesthetics and La
Page 60 and 61: SMG-9 Figure 25 Schematic of a Stor
Page 62 and 63: When an extended detention orifice
Page 64 and 65:
The forebay should meet the followi
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Requiring, during design, safety fe
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Until recently, the filling and dra
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The most common design priority for
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SMG-9.4.7.1.2 Water Quality Volumes
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The design steps are the following:
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For the purposes of this guideline,
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SMG-9.4.8.7 Detailed Design Procedu
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This is indicated on SMG-9 Figure 3
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SMG-9 Figure 37 - Waitakere City Co
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SMG-9.4.9.7.7 Stormwater Management
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SMG-8 Figure 8b - Information on ra
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SMG-9.4.10.5 Advantages of Water Ta
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SMG-9 Figure 39 Calculation of Rood
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The 15% wastage factor accounts for
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Commercial and industrial sites wil
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SMG-9 Table 24 Stormwater Managemen
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SMG-9.4.11.2 Separator Size The siz
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VH = Q/1.125 Calculate the surface
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When an outfall is sited in a coast
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SMG-9.5.1.3 Riprap Aprons Outlet pr
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SMG-9 Figure 46 Angled Entry of Out
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SMG-9 - Appendix A Case Studies SMG
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SMG-9 Apx A.2 Filter Strip Case Stu
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SMG-9 Apx A.3 Sand Filter Case Stud
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SMG-9 Apx A.4 Rain Garden Case Stud
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SMG-9 Apx A.5 Infiltration Case Stu
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SMG-9 Apx A.6 Ponds Case Study SMG-
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SMG-9 Table A.6.3 Stage-Storage Rel
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Outflow from ED orifice = Q = 0.62A
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= (Qn/d 1.67 s 0.5 ) - Zd b = ((.04
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SMG-9 Apx A.8.3 Design Water qualit
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SMG-9 Apx A.9 Green Roof Case Study
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Extended detention orifice sizing -
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The minimum width and depth require
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SMG-9 Table B.1.2a Particle Charact
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Particle Diameter (µm) SMG-9 Table
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SMG-9 Figure B.1.3 Wetland Process
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Plants do take up nutrients or meta
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