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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
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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
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Stormwater Management Design Guidelines (15 Nov 2011)
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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
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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
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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
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Stormwater Management Design Guidelines (15 Nov 2011)
AI-TACHMEN1-4._._.I a °fOREPORT4-c-S-43-1I
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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)