Hillingdon SuDS Design & Evaluation Guide

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Detailed Design 9.10 Planting design for SuDS The choice of vegetation cover and plant species is an important aspect of designing SuDS systems and features. Vegetation is an inherent functional part of any soft-landscape SuDS feature as well as being about aesthetics, usability and wildlife benefits. Vegetation type and species selection can significantly affect hydraulic and pollution control functionality as well as the contribution to amenity and biodiversity. The SuDS plant palette will often vary from conventional landscape design for reasons of SuDS functionality, different ground conditions and to protect the wider environment from chemical contamination. Strutts Centre, Belper. Contemporary ‘prarie’ planting in raingarden collecting roof runoff and access road runoff. 113 9.10.1 Objectives of planting design for SuDS SuDS planting design should satisfy general planting design criteria and relies on an awareness of the landscape maintenance requirements. In addition, planting should fulfill specific SuDS functions, such as: ■■ ■■ ■■ preventing soil erosion trapping silt and pollution from runoff encouraging interception (evaporation, infiltration and transpiration) ■■ ■■ ■■ augmenting biodiversity by structure, species richness and careful management (refer to the Biodiversity section 9.9) creating attractive surroundings and community amenity protection of the environment by avoiding the need for herbicides, pesticides or fertilizer treatment. ■■ enabling long term infiltration by opening soil profiles through the root growth cycle London Borough of Hillingdon SuDS D & E Guide © 2018 McCloy Consulting & Robert Bray Associates
9.10.2 The Principles of SuDS planting selection & design SuDS vegetation choice and design should achieve the following: ■■ ■■ ■■ General planting design should connect with the SuDS landscape, ideally with grassland, woodland or ornamental planting creating linkages for visual benefit and biodiversity. The design criteria set out in the Biodiversity section (9.9) should be followed where appropriate. Vegetation should permanently cover the ground, both in summer and winter, to prevent erosion of the soil surface. The matrix of roots, stems and leaves of vegetation slows the flow of runoff, filtering water and encouraging silt to settle out in components like filter strips, swales and basins. SuDS planting is often naturalistic in character, particularly where SuDS are being applied to a greenfield site. Naturalistic planting is usually the most appropriate, providing maximum biodiversity benefits as well as being cost effective, resilient and most likely to have modest long term maintenance requirements. In built up areas a more formal and ornamental design style may be required for raingardens, bio-retention features and green / blue roof surfaces. Recent research by the Royal Horticultural Society (RHS) has demonstrated that ornamental plants, close to the wild type, especially from the northern hemisphere can provide similar benefits to wildlife as native planting but the capital cost and management can be more difficult and expensive. Detailed Design ■■ A vigorous growth of vegetation, particularly when forming an extensive Contract arrangements should always allow for additional or remedial works to ensure the 114 root mat, encourages natural losses into integrity of vegetation surfaces that perform the ground throughout rainfall events. a SuDS function. ■■ Planting design should avoid fertilizer, pesticides or herbicides wherever possible to avoid leaching of chemicals into the SuDS and groundwater. They should use careful plant selection and a soil conditioner such as ‘green waste compost’ as an alternative to suppress weed growth and improve soil fertility. Strutts Centre, Belper. Brick channels collect roofwater for linear raingarden with garden style planting. London Borough of Hillingdon SuDS D & E Guide © 2018 McCloy Consulting & Robert Bray Associates
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Sustainable Drainage Design & Evalu
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Contents 1.0 Introduction 2.0 Under
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This development guide has the supp
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1.2 SuDS today There have been a nu
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2.0 Understanding Rainfall It is im
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Where the ground is impermeable, wa
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Overview 3.0 The Impact of Developm
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Overview 3.3 Consequences of piped
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Overview 4.0 The Role of SuDS Susta
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Overview SuDS schemes offer diverse
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Overview 5.0 The SuDS Design & Eval
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Overview 5.3 The objectives of the
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Local SuDS requirements 21 6.0 Land
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Local SuDS requirements 23 Local Su
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Concept Design for Holyoakes School
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7.4 Concept Design process 7.4.1 Fl
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Modifi Step 2 - Modified Flow Route
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7.4.3 Collection of runoff from har
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7.4.5 Conveyance of runoff between
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A flow control generally defines th
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Additional considerations for infil
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7.4.9 Preliminary flow and volume c
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7.4.11 Managing runoff from site If
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Concept Design 45 7.4.13 Flow rate
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Concept Design Long Term Storage Su
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Concept Design 7.5 Concept informat
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Concept Design 51 7.5.3 Preliminary
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Concept Design 7.5.6 Management and
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5. Quality Confirm ‘treatment sta
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8.2 Objectives of SuDS Outline Desi
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8.4 Design criteria considerations
Page 67 and 68: 8.5.2 Aspects of Health and Safety
Page 69 and 70: 8.8 Outline information required fo
Page 72 and 73: Detailed Design 9.0 Design and Eval
Page 74 and 75: Detailed Design 9.3 Typical Detaile
Page 76 and 77: Detailed Design 71 Plan excerpt: pr
Page 78 and 79: Detailed Design 73 9.3.4 Detailed D
Page 81 and 82: 9.4 Critical levels Levels are impo
Page 83 and 84: 9.5.3 Calculation processes Calcula
Page 85 and 86: 9.5.4.3 Making allowances for inter
Page 87 and 88: 9.5.4.6 Accounting for Climate Chan
Page 89 and 90: 9.5.5 Calculating storage requireme
Page 91 and 92: Approach 2 Where volumes cannot be
Page 93 and 94: Detailed Design 88 Designers should
Page 95 and 96: Detailed Design Lamb Drove, Cambour
Page 97 and 98: Parameter Modelling of the SuDS lay
Page 99 and 100: 9.6.1 Design flexibility A framewor
Page 101 and 102: 9.6.4 Single, tiered storage compon
Page 103 and 104: 9.6.6 The importance of protected o
Page 105 and 106: the 1 in 100 flow rate - for exampl
Page 107 and 108: 9.7 Water quality Rainfall picks up
Page 109 and 110: For low to medium risk sites, the i
Page 111 and 112: 9.7.5 Water quality design checklis
Page 113 and 114: 9.8.2 Accessibility All parts of th
Page 115 and 116: Firstly the collection and conveyan
Page 117: 9.9.3 Key design criteria for biodi
Page 121 and 122: Amenity grass An everyday grass sur
Page 123 and 124: Meadow vegetation Meadow vegetation
Page 125 and 126: Bioretention features are defined b
Page 127 and 128: 9.10.3.4 A place for trees and shru
Page 129 and 130: Source Controls providing collectio
Page 131 and 132: Raingardens The raingarden concept
Page 133 and 134: Permeable surfaces Permeable surfac
Page 135 and 136: Filter drains Filter drains, someti
Page 137 and 138: Filter strips The hard edge from a
Page 140 and 141: Detailed Design 135 The safety cons
Page 142 and 143: Detailed Design 9.11.5 Storage stru
Page 144 and 145: Detailed Design 9.12 Management of
Page 146 and 147: Detailed Design 9.12.3 Example of S
Page 149: Sheffield Grey to Green : an excell
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Hillingdon SuDS Design & Evaluation Guide

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