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HomeMy WebLinkAboutCS 43-11 l Cif Report To Executive Committee 6 2 ICKERING Report Number: CS 43-11 Date: December 5, 2011 From: Everett Buntsma Director, Community Services Subject: Stormwater Management Design Guidelines Recommendation: 1. That Report CS 43-11 of the Director, Community Services, regarding the Stormwater Management Design Guidelines be received; 2. That Council endorse the Stormwater Management Design Guidelines; and 3. That Staff be authorized to release these guidelines to the holders of the City's Development Control Design Standards as an addendum, and to provide the electronic version to the public upon request. Executive Summary: The Stormwater Management Design Guidelines were prepared by Valdor Engineering Inc. for the City and they represent the best-practices and standards for the design of stormwater management facilities and storm drainage infrastructure, and are consistent with guidelines currently being used in other Greater Toronto Area municipalities. The guidelines will ensure that newly constructed stormwater management facilities and storm drainage systems in Pickering are robustly designed using standardized procedures, are operating in conformity with the Ontario Ministry of the Environment Certificate of Approval prior to assumption, and that the City's future operation and maintenance costs are minimized. Due to the length of the document it was not included as an attachment. However, the Table of Contents is attached for reference. Financial Implications: There are no direct financial implications to the City on endorsing the Stormwater Management Guidelines, however through the adherence to these guidelines in the designs of stormwater management facilities and storm drainage infrastructure, reductions to future operations and maintenance costs will be achieved. b ~ort CS 43-11 December 5, 2011 Subject: Stormwater Management Design Guidelines . Page 2 The guidelines will be incorporated into the City's Development Control Design Standards. The City currently charges a fee of $50 for a hard copy of the Development Control Design Standards. Those that have already purchased a copy of the Development Control Design Standards will be sent a complimentary copy of the Stormwater Management Design Guidelines. Sustainability Implications: The Stormwater Management Design Guidelines are consistent with the City's five sustainability objectives of a healthy environment, society, economy, responsible development and responsible consumption. The guidelines represent a more sustainable approach to stormwater management through implementing a treatment train approach and maintaining the water balance. Furthermore, the guidelines are in conformity with the City's corporate priorities, particularly with respect to financial management, corporate best practices and sustainable placemaking. Background: The field of stormwater management has evolved rapidly since it was introduced in Ontario in the 1980s and it is now a regulatory requirement of the Ontario Ministry of the Environment (MOE), the Ontario Ministry of Natural Resources (MNR), the Toronto and Region Conservation Authority (TRCA) and the Central Lake Ontario Conservation Authority (CLOCA). Due to constraints on Pickering's urban area, the City has not experienced the rapid growth and the accompanying stormwater management infrastructure that surrounding Greater Toronto Area (GTA) municipalities have experienced over the last two decades. As a result, the City does not currently have Stormwater Management Guidelines and relies upon guidance from the MOE, TRCA and MNR. In the coming years, the City of Pickering will be undergoing a period of rapid urban expansion through the development of the Seaton lands. Due to the presence of Red Side Dace, which is protected by the Endangered Species Act (MNR, 2007), the stormwater management requirements in Seaton will be some of the most stringent in Ontario. The regulatory requirement for stormwater management will result in a large amount of new stormwater management infrastructure, including potentially over 60 stormwater management facilities as well as numerous Low Impact Development facilities as Seaton develops. These facilities will be operated and maintained by the City following assumption of services. The majority of municipalities in the Greater Toronto Area (GTA) have developed stormwater management guidelines to ensure that stormwater management infrastructure is designed to their specifications. The purpose of this project was to review the best-practices from GTA municipalities and produce stormwater management guidelines for the City of Pickering, which reflect current industry standards and minimize the City's future operations and maintenance costs. CORP0227-07/01 revised Report CS 43-11 December 5, 2011 64 Subject: Stormwater Management Design Guidelines Page 3 Regulatory Compliance: The MOE requires that a Certificate of Approval (C of A) is obtained for all new stormwater management facilities. The C of A is a legal document specifying the expected performance of the stormwater management facility. Through the assumption of services, the City assumes the legal responsibility for ensuring that the stormwater management facility is, and continues to be, in compliance with the C of A. The need for monitoring to prove that a stormwater management facility is functioning in accordance with the C of A has been a requirement of other GTA municipalities, most notably the Town of Richmond Hill, since the early 2000s. In the case of the Town of Richmond Hill, their monitoring program has identified numerous deficiencies which developers were required to address prior to their stormwater management facilities being assumed. Other GTA municipalities experiencing rapid urban growth, such as the Town of Ajax and the Town of Oakville, have followed Richmond Hill's lead in terms of requiring a monitoring program prior to assumption of stormwater management facilities. The MOE has recently begun the process of enforcing C of A's issued for stormwater management facilities. Recently, the Town of Ajax, the Town of Whitby and the City of Guelph have been asked to provide documentation to demonstrate C of A compliance on their stormwater management facilities. To ensure that all future stormwater management facilities assumed by the City are in compliance with the C of A prior to assumption, the City has developed requirements for monitoring them as part of the Stormwater Management Design Guidelines. The purpose of the monitoring program is to protect the City from the significant financial liability of MOE ordering the retrofit of stormwater management facilities which are not in compliance with the C of A. Highlights: The major changes to existing Pickering standards resulting from the preparation of the guidelines are as follows: • Standardized methods for completing hydrologic and hydraulic calculations will be used; • Storm sewer pipes will be sized using local rainfall data; • Increased protection against basement flooding; • Formal flooding depth and velocity criteria for major system flow on roads; • Access roads will be built to all new stormwater infrastructure to facilitate future maintenance; • Warning signs will be posted at all stormwater management facilities to inform the public of the potential hazards; CORP0227-07/01 revised ~pport CS 43-11 December 5, 2011 J Subject: Stormwater Management Design Guidelines Page 4 • Prior to assumption by the city, new stormwater infrastructure must demonstrate through a monitoring program that are in compliance with the C of A; and • Detailed design guidelines for stormwater management ponds. Development: The new guidelines were developed by Valdor Engineering Inc. and the Engineering Services Division in consultation with.the Operations Section of the Community Services Department and Development Control Section of the Planning and Development Department. The new guidelines are a culmination of existing standards used in Pickering and elsewhere throughout the GTA (Ajax, Toronto, Richmond Hill, Markham, Vaughan, Barrie and Kitchener) and they represent industry standard approaches to stormwater management and storm drainage systems. In developing the guidelines, an effort was made to be consistent with guidelines from bordering municipalities - most notably the Town of Ajax, which updated their stormwater management guidelines in early 2011. As the content of the guidelines is currently being applied in other GTA municipalities, a formal consultation process with engineering consultants and regulatory agencies was not deemed necessary. Applicability: The Stormwater Management Design Guidelines will be incorporated into the City of Pickering's Development Control Guidelines to provide a "One-Stop Shop" for developers and their consultants with all the information required to meet the City's development standards. In addition to greenfield development, the guidelines will also form the basis for undertaking stormwater management studies for small infill developments located throughout the existing urban city centre. Standard methodologies are required to simply, but accurately, reflect the on-site requirements for water quality and quantity control as well as water balance and in-stream erosion control. To the extent practical, the guidelines will be'applied to City initiated projects where stormwater management infrastructure is being constructed or upgraded as part of retrofit projects. The guidelines will be periodically updated to ensure that they are reflective of best practices in stormwater management. Attachments: 1. Table of Contents - Stormwater Management Design Guidelines CORP0227-07/01 revised Report CS 43-11 December 5, 2011 66 Subject: Stormwater Management Design Guidelines Page 5 Prepared By: Approved/Endorsed By: Tom Dole, P.Eng. / Everett Buntsma Water Resources Engineer 0 Director, Community Services V Marilee Gadzovski, M.Sc. ng.), P.Eng. Senior Water Resources and Environmental Engineer Richfard Holbor', P.Eng. DFsion Head, Engineering Services TD:td Copy: Chief Administrative Officer Recommended for the consideration of Pickering ty Council / ko mi, ~ Z 21, ZD/( Tony Prevedel, P.Eng. Chief Administrative Officer CORP0227-07/01 revised ATTACH MENT# TO REPORT# CS L43-11 of _ 0 67 ICI 1 I PICI~ERUNG STORMWATER MANAGEMENT DESIGN GUIDELINES 15 November 2011 fiTTACHMENT#1'OREPORT# CS 43-11 68 Table of Contents 1.0 GENERAL POLICIES AND PRINCIPLES 7 1.1 INTRODUCTION 7 1.2 DESIGN RESPONSIBILITIES 7 1.3 THE NEED FOR STORMWATER MANAGEMENT 8 1.4 STORMWATER MANAGEMENT POLICIES AND PRINCIPLES 9 1.5 ENVIRONMENTAL AND MUNICIPAL LAND USE PLANNING 10 1.5.1 Introduction . 10 1.5.2 Environmental and Land Use Planning 10 1.5.3 Watershed Plan 10 1.5.4 Master Environmental Servicing Plan 12 1.5.5 Neighbourhood Functional Servicing and Stormwater Reports 12 1'.5.6 Functional Servicing and Stormwater Reports 12 1.5.7 Stormwater Management Report 12 1.5.8 Municipal Class Environmental Assessment 13 2.0 LEGISLATION - ACTS AND REGULATIONS ...................................................15 3.0 STORMWATER DRAINAGE SYSTEM DESIGN GUIDELINES ........................17 3.1 MINOR SYSTEM 18 3.1.1 Storm Sewer Design 19 3.1.2 Foundation Drains 24 3.2 MAJOR SYSTEM 26 3.2.1 Roadway Crossings 30 4.0 STORMWATER MANAGEMENT CRITERIA 31 4.1 WATER QUANTITY CONTROL CRITERIA 31 4.2 IN-STREAM EROSION CONTROL CRITERIA 32 4.3 WATER QUALITY CONTROL CRITERIA 33 5.0 STORMWATER MANAGEMENT DESIGN GUIDELINES .................................34 5.1 SOURCE CONTROLS 35 5.1.1 Reduced Lot Grading 35 5.1.2 Roof Leader Discharge to Surface 35 5.1.3 Roof Leader Discharge to Soakaway Pits 35 5.1.4 Rear Lot Ponding 36 5.1.5 Greenroofs 36 5.1.6 Rooftop Storage 36 5.1.7 Surface Storage 36 5.1.8 Detention Vaults 37 City of Pickering Page 2 Stormwater Management Design Guidelines (15 Nov 2011) ATTACHMENT# TO REPORT# CS I 69 3 of 5.1.9 Porous and Pervious Pavement 37 5.1.10 Bioretention 37 5.1.11 Soil Amendments 37 5.2 CONVEYANCE CONTROLS 38 5.2.1 Oversized (Super) Pipes 38 5.2.2 Pervious Pipe Systems 38 5.2.3 Bioswales and Enhanced Grassed Swales 38 5.3 END-OF-PIPE CONTROLS ...................................................................................'39 5.3.1 Infiltration Trenches 39 5.3.2 Sand Filters 39 5.3.3 Vegetated Filter Strips 39 5.3.4 Oil/Grit Separators 5.3.5 Extended Detention Wet Ponds 41 5.3.6 Dry Ponds 41 5.3.7 Infiltration Basins 41 5.4 STORMWATER MANAGEMENT FACILITIES (WET PONDS AND WETLANDS) 42 5.4.1 General Siting Guidelines 42 5.4.2 Length-to-Width Ratio 42 5.4.3 Grading (Side slope) and Retaining Walls 42 5.4.4 Water Levels 43 5.4.5 Permanent Pool, Quality and Quantity Storage Requirements 43 5.4.6 Forebay ......................................................................................................44 5.4.7 Berming 45 5.4.8 Sediment Drying Area 46 5.4.9 Maintenance Access Roadway 46 5.4.10 Fencing .......................................................................................................47 5.4.11 Aesthetics ...................................................................................................47 5.4.12 Warning Signage 47 5.4.13 Inlet Structures 47 5.4.14 Outlet Control Structures 48 5.4.15 Emergency Spillway 49 5.4.16 Major System Overland Flow Routes 49 5.4.17 Anti-seepage Collars 49 5.4.18 Existing Groundwater Elevation 49 5.4.19 Liners 50 5.4.20 Fire Use 51 5.4.21 West Nile Virus 51 5.4.22 Thermal Impacts .........................................................................................51 5.4.23 Trails ...........................................................................................................52 5.4.24 Maintenance and Inspections Protocol 52 5.4.25 Naturalized vs. Manicured SWM Facilities 52 5.4.26 Fountains and Bubblers 52 5.4.27 Stormwater Management Facility Planting Guidelines 52 City of Pickering Page 3 Stormwater Management Design Guidelines (15 Nov 2011). ATTACHMENI'g,__ - TOREPORT# ~S 3--11 of 7 0 6.0 GUIDELINES FOR HYDROLOGIC AND HYDRAULIC ANALYSIS 53 6.1 GUIDANCE ON THE USE OF COMPUTER PROGRAMS BY PROFESSIONAL ENGINEERS 53 6.2 HYDROLOGY 55 66.2.2.1 Event Based Hydrologic Models 55 6.2.2 Continuous Models 56 6.2.3 Rational Method 56 6.2.4 Rainfall ................................................................60 6.2.5 Time of Concentration 61 6.2.6 Calculation of Model Parameters 67 6.3 HYDRAULICS 73 6.3.1 Minor System Hydraulic Calculations and Hydraulic Grade Line Analysis.. 75 6.3.2 Culvert l Bridge Hydraulic Analysis 79 7.0 CONSTRUCTION SEDIMENT AND EROSION CONTROL METHODS 80 8.0 ENGINEERING SUBMISSION REPORTING REQUIREMENTS (DRAINAGE DESIGNS, SWM REPORTS, OPERATION AND MAINTENANCE MANUALS) 82 8.1 GUIDELINES ON THE USE OF THE ENGINEERS' SEAL 82 8.2 SUBMISSIONS TO EXTERNAL AGENCIES 84 8.3 GUIDELINES ON RESPONSES TO COMMENTS 85 8.4 REPORTING REQUIREMENTS FOR CONCEPTUAL/ PRELIMINARY SWM PLANS (PRELIMINARY SWM REPORT, FUNCTIONAL SWM REPORT, FUNCTIONAL SERVICING REPORT) 86 8.5 REPORTING REQUIREMENTS FOR DETAILED SWM PLANS (DETAILED DESIGN)....... 90 8.6 REPORTING REQUIREMENTS FOR SWM FACILITY OPERATION AND MAINTENANCE MANUALS (DETAILED DESIGN) 95 8.7 DESIGN DOCUMENTATION FOR NATURAL CHANNEL DESIGN 98 9.0 STORMWATER MANAGEMENT FACILITY PERFORMANCE MONITORING 99 9.1 GENERAL ..........................................................................................................99 9.2 SWM POND 99 9.3 BIOSWALE .......................................................................................................102 9.4 INFILTRATION TRENCH 102 10.0 REFERENCES .................................................................................................104 11.0 GLOSSARY OF TERMS ..................................................................................107 City of Pickering Page 4 Stormwater Management Design Guidelines (15 Nov 2011) ATTACHIIENT9 K- REPORT # ! S L[.3 71 m of List of Tables Table 1 - Manning's Roughness Coefficients for Pipes .................................................19 Table 2 - Pipe Size and Pipe Materials 20 Table 3 - Hydraulic Losses for Alignment Changes 21 Table 4 - Major System Criteria 28 Table 5 - Permissible Depths and Velocities for Major System Flow Paths 28 Table 6 - Roadway Crossing Hydraulic Requirements 30 Table 7 - MOE Particle Size Distribution 41 Table 8 - Pond and Wetland Depth Requirements ........................................................43 Table 9 - Pickering Standard Runoff Coefficients by Land Use 58 Table 10 - Pickering Standard Runoff Coefficients by Ground Cover and Slope 59 Table 11 - Pickering Standard Runoff Coefficients for Pervious Areas 59 Table 12 - Pickering IDF Parameters 60 Table 13 - Manning's "n" Roughness Coefficients for Overland Flow 65 Table 14 - Intercept Coefficient for Shallow Concentrated Flow Equation 66 Table 15 - Manning's Roughness Coefficients for Channelized Concentrated Flow 67 Table 16 - Curve Numbers for Selected Land Uses 67 Table 17 - Initial Abstraction / Depression Storage 69 Table 18 - Typical Impervious Values by Land Use 69 Table 19 - Typical Parameter Values for Horton Infiltration Method 71 Table 20 - Typical Parameter Values for Green-Ampt Infiltration Method 72 City of Pickering Page 5 Stormwater Management Design Guidelines (15 Nov 2011) AI-TACHMEN1-4._._.I a °fOREPORT4-c-S-43-1I of 72 List of Figures Figure 1 - Land Use Change and the Hydrologic Cycle (US EPA, 2007) 8 Figure 2 - City of Pickering Environmental Planning Process .......................................11 Figure 3 - Overland Flow Components 6,1 Figure 4 - Examples of catchments that may be subject to partial area effects (Queensland Urban Drainage Manual, 2007) 63 Appendices Appendix A - Storm Sewer Design Sheet and Standard Drawings Appendix B - OF Data, Design Storms, CN Value Conversion Table Appendix C - Design Examples Appendix D - TRCA Planting Guidelines City of Pickering Page 6 Stormwater Management Design Guidelines (15 Nov 2011)