Conveyance and End-of-Pipe Measures for Stormwater - FCM

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4. Applications and Limitations 4.4 Management Practices Table 4–1a Application of Conveyance Control Best Management Practices 4.4 Management Practices Table 4–1a: Application of Conveyance Control Best Management Practices Stream Corridor Protection and Enhancement (mostly as a mitigation measure) Application Requirements Opportunities and Limitations Proven Effectiveness Implementation is easy and can be accomplished through volunteers. Primarily used in agricultural, parkland, new, or redevelopment areas. Depends on public education to be effective. Opportunities identified based on new development or redevelopment areas and physical implementation criteria. Performance depends on other characteristics of the stream corridor. Its performance is difficult to measure directly. Cost Capital cost: low. Operation and maintenance costs: low. Channel Modification (mostly as a mitigation measure) Application Requirements Opportunities and Limitations Proven Effectiveness Cost Applied within the stream corridor. Requires available land, detailed modelling, and geomorphic assessment. Must assess impacts downstream and upstream. Opportunities identified based on land and space requirements, fisheries objectives, and physical implementation criteria. Generally effective in restoring a self-maintaining stable channel. Failures typically occur if bankfull is set too low and frequent overtopping occurs. Modification of roughness by adding rock is a proven practice. Capital cost: low for restoration projects and high for creation projects. Operation and maintenance costs: low. Capital cost: low for restoration projects and high for creation projects. Operation and maintenance costs: low. Application Requirements Opportunities and Limitations Proven Effectiveness A site investigation, combined with analyses of bank failure mechanism, flow and soil conditions are required to determine which bank protection method to apply. Methods range from one or a combination of vegetation, rock, wood, brush, and fabrics. Consideration must be given to access, maintenance, urgency, and availability of materials. Opportunities identified based on land and space requirements, fisheries objectives, and physical implementation criteria. Effectiveness is proven if the strength of the protection matches the forces of the attack by the stream. In many cases, bank protection methods have provided long-term protection and the stability required for ecological recovery. Cost Capital cost: medium. Operation and maintenance costs: low. Roadside Ditches Application Requirements Opportunities and Limitations Proven Effectiveness Roadside ditches are most effectively applied where soils are non-erodible; ideally slopes are > 2%; and space is available for the channel cross-section. Opportunities identified based on land use, soil, ground topography, and availability of space. Also identified by the condition of the roads and existing sewer pipes in an area. More economical to be considered with the reconstruction of roads. Public perceptions vary. Some urban residents view ditches as an eyesore. Other communities like the rural character of streets with ditches. Cost Capital cost: medium. Operation and maintenance: low. 34 Conveyance and End-of-Pipe Measures for Stormwater Control — July 2005
Table 4–1a: Application of Conveyance Control Best Management Practices (continued) Grassed or Vegetated Swales Application Requirements Opportunities and Limitations Proven Effectiveness They are primarily applicable for new or redevelopment areas with appropriate physical conditions. Infiltration or filtration requires an area with pervious soils (generally, an infiltration rate of > 15 mm/hr), bedrock and water table > 1 m below bottom of swale, and slope between 0.5% and 5% in the direction of flow. Opportunities identified are based on new development or redevelopment areas with suitable soil conditions. Opportunities are also identified by the size of the drainage area (< 15 ha) and the condition of roads and existing sewer pipes in the area. More economical to be considered with the reconstruction of roads. Effective in low-grade areas, pervious soils, and for relatively short length. Most effective with a channel slope between 1% and 2%, a bottom width of min. 750 mm and grass height 75 mm. Low-gradient swales with check dams have slightly higher removal rates than high-slope swales without check dams. Cost Capital cost: low. Operation and maintenance costs: low. Pervious Pipe Systems Application Requirements Opportunities and Limitations Proven Effectiveness Small drainage area (< 6 ha). Pre-treatment of road runoff may be required. Require areas with pervious soils (minimum infiltration rate of 15 mm/hr), bedrock and water table > 1 m below bottom of drainage media, slope between 0.5% and 5% (ideally 1% to 2%) in the direction of flow. Minimum setback from building foundations: 3 m down gradient (towards the building) and 30 m up gradient (away from the building). Not suitable in locations receiving large sediment loads. Opportunities identified based on the presence of certain surface features, and the condition of the roads and existing sewer pipes in an area. More economical to be considered with the reconstruction of roads. Few applications in Ontario. These systems are experimental and clogging problems have been experienced. Cost Capital cost: high. Operation and maintenance costs: medium. Pervious Catch Basins Application Requirements Opportunities and Limitations Proven Effectiveness Small drainage area (< 6 ha). Not suitable in locations that receive a large sediment load that could clog the pre-treatment system. Pre-treatment of road runoff may be required. New or redevelopment area with pervious soils (minimum infiltration rate of 15 mm/hr), and bedrock and water table > 1 m below bottom of drainage media. Opportunities identified based on the presence of certain surface features, and the condition of the roads and existing sewer pipes in an area, also by the project catchment area (< 15 ha). More economical to be considered with the reconstruction of roads. As with pervious pipe systems, varying results have been reported. Problems would result from poor design, poor construction practices, poor site physical conditions, or inadequate stabilization of development before construction. Cost Capital cost: high. Operation and maintenance costs: medium. Conveyance and End-of-Pipe Measures for Stormwater Control — July 2005 35 4. Applications and Limitations 4.4 Management Practices Table 4–1a Application of Conveyance Control Best Management Practices (continued)
Page 1 and 2: National Guide to Sustainable Munic
Page 3 and 4: INTRODUCTION InfraGuide ® - Innova
Page 5 and 6: TABLE OF CONTENTS Acknowledgements
Page 7 and 8: ACKNOWLEDGEMENTS The dedication of
Page 9 and 10: EXECUTIVE SUMMARY Increasing urbani
Page 11 and 12: 1. General 1.1 Introduction Urbaniz
Page 13 and 14: Design storm — A rainfall event o
Page 15 and 16: 2. Rationale 2.1 Urban Stormwater T
Page 17 and 18: 2.2.3 Impacts on Stream Habitat Alo
Page 19 and 20: 3. Conveyance and End-of-Pipe Best
Page 21 and 22: Table 3-1: Evaluation Criteria for
Page 23 and 24: 3.3 Description of Best Management
Page 25 and 26: Table 3-3a: Conveyance Control Best
Page 27 and 28: Table 3-3b: End-of-Pipe Control Bes
Page 29 and 30: Table 3-3b: End-of-Pipe Control Bes
Page 31 and 32: Do any physical constraints at the
Page 33: 4. Applications and Limitations Tab
Page 37 and 38: Table 4-1b: Application of End-of-P
Page 43 and 44: 5. Evaluation of Facilities 5.1 Ope
Page 45 and 46: Appendix A: Stormwater Best Managem
Page 47 and 48: Figure A-7: Pervious pipe exfiltrat
Page 49 and 50: A.2.3 Constructed Wetlands Referenc
Page 51 and 52: Figure A-17: Cutaway of a Swirl Con
Page 53 and 54: Appendix B: Design Examples B.1 Des
Page 55 and 56: B.2 Design Example: Development of
Page 57 and 58: B.3 Design Example: Sedimentation F
Page 59 and 60: References AEP (Alberta Environment
Page 61 and 62: Sabourin Kimble & Associates, 1999.

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