Technical Guidelines for Stormwater Management (SWM ...

1 If you require content in an alternate format please contact us at 905-895-1281 or by email at LSRCA Technical Guidelines for Stormwater Management Submissions Approval Date: June 24, 2016 Effective Date: September 1, 2016 ii TABLE OF CONTENTS INTRODUCTION .. 1 Environmental Planning and Stormwater Management .. 2 Stormwater Management .. 3 Stormwater Management Requirements .. 5 Stormwater Quantity Control .. 7 Peak Flow Control .. 7 Volume Control .. 7 Stormwater Volume Control Requirements .. 7 Flexible Treatment Alternative for Sites with Restrictions .. 8 Major-Minor System Conveyance .. 10 Regulatory Storm Conveyance .. 10 Stormwater Quality Control .. 11 Suspended Solids .. 11 Phosphorus .. 11 Winter Salt .. 12 Temperature .. 12 Other Contaminants .. 13 Oil, Grease and Gas .. 13 Heavy Metals.

2 14 Stream Erosion Control .. 14 Water Balance/Groundwater Recharge .. 14 Erosion and Sediment Control .. 16 Soil Erosion .. 16 Erosion Control Requirements .. 17 MODELLING and Stormwater Management (SWM) FACILITY DESIGN .. 18 Hydrologic Analysis .. 18 Hydraulic Analysis .. 19 Stormwater Management (SWM) Facility Design .. 19 Lot Level and Conveyance Controls or Low Impact Development (LID) .. 19 Design Requirements .. 20 Parking Lot Storage and Rooftop 23 Manufactured Treatment Devices (MTDs) .. 24 Oil/Grit Separators .. 24 Filtration Devices .. 25 Maintenance Requirements .. 25 Stormwater Management Report Submission .. 26 Stage 1 and 2 Reports .. 26 Re-Submission .. 27 Climate Change .. 27 GLOSSARY .. 29 REFERENCES .. 31 iii APPENDICES APPENDIX A Stormwater Management (SWM) REPORT MINIMUM REQUIREMENTS APPENDIX B PEAK FLOW CONTROL CREDITS INFILTRATION SYSTEMS APPENDIX C TYPICAL HYDROLOGIC VALUES AND REFERENCES APPENDIX D MANUFACTURED TREATMENT DEVICES APPENDIX E PHOSPHORUS LOADING APPENDIX F CRITERIA FOR STREAM EROSION CONTROL STUDY APPENDIX G EROSION AND SEDIMENT CONTROL MINIMUM REQUIREMENTS APPENDIX H MINIMUM PLANTING REQUIREMENTS APPENDIX I TYPICAL HYDRAULIC VALUES AND REFERENCES APPENDIX J IMPLEMENTATION Guidelines FIG.

3 17 APPENDIX K MINIMUM REQUIREMENTS FOR ENGINEERING SUBMISSIONS: FLOODPLAIN MAPPING, SURVEY AND GEOSPATIAL DATA iv NOMENCLATURE 1D One Dimensional 2D Two Dimensional 3D Three Dimensional AES Canadian Atmospheric Environment Services AMC Antecedent Moisture Conditions BMP(s) Best Management Practice(s) Certified Engineering Technologist CAD AutoCAD Software Program CD Compact Disc CHI Computational Hydraulics Incorporated cm Centimetre CN Curve Number CN* Modified Curve Number CVC Credit Valley Conservation DTM Digital Terrain Model DVD Digital Video Disc EC Consolidated frequency analysis EIS Environmental Impact Study EOP End of Pipe EPA Environmental Protection Agency ESC Erosion and Sediment Control etc. Etcetra Et al And others ETV Environmental Technology Verification FSR Functional Servicing Report Geo-X Stream Modelling Software GIS Geographic Information System ha Hectare HEC2 Army Corps of Engineering Hydraulic Modelling Software HEC-RAS Army Corps of Engineering Hydraulic Modelling Software hr Hour HSG Hydrologic Soil Group HY-8 Federal Highway Administration Hydraulic Modelling Software HYMO Hydrologic Modelling Software For example Ia initial Abstraction ICD Inlet Control Device ID Identification IDF Intensity Duration Frequency IF Infiltration Facility In/hr inches per hour kg/ha/yr Kilogram per hectare per year km2 Square Kilometre LID Low Impact Development LIDAR Light Detection and Ranging Survey Technology LNAPL Light Non-Aqueous Phase Liquid LSEMS Lake Simoce

4 Environmental Management Strategy LSPP Lake Simcoe Protection Plan v LSRCA Lake Simcoe Region Conservation Authority m Metres m asl Elevation in metres above sea level m2 Square Metres m3 Cubic Metres m3/ha Cubic Metres per Hectare m3/s Cubic Metres per second mm/h Millimeter per hour Manning s n Roughness Coefficient MDP Master Drainage Plan MESP Master Environmental Servicing Plan mm Millimetre MMAH Ministry of Municipal Affairs and Housing MNR Minitry of Natural Resources MNRF Ministry of Natural Resources and Forestry MOE Ministry of the Environment MOECC Ministry of the Environment and Climate Change MOI Ministry of Infrastructure MPCA Minnesota Pollution Control Agency MSP Master Servicing Plan MTDs Manufactured Treatment Devices MTO Ministry of Transporation NAD North American Datum NASHYD Rural Catchment Modelling Routine NJDEP New Jersey Department of Environmental Protection O&M Operation and Maintenance Ontario Regulation OCCS Ontario Climate Change Strategy OGS Oil Grit Separator OLS Ontario Land Surveyor ORMCP Oak Ridges Moraine Conservation Plan OTTHYMO HYMO Based Hydrologic Modelling Software P.

5 Eng. Professional Engineer Professional Geoscientist PCSWMM SWMM5 Based CHI Modelling Suite PPS Provincial Policy Statement Right of Way SCS United States Natural Resource Conservation Service formerly Soil Conservation Service SGBLS South georgian Bay Lake Simcoe Statues of Ontario SP Secondary Plan SPMDD Standard Proctor Maximum Dry Density SPP Source Protection Plan Square Feet STANDHYD Urban Catchment Modelling Routine SWM Stormwater Management SWMM5 EPA SWM Modelling Software Tc Time of Concentration TIMP Total Impervious Area vi TIN Geospatial Surface Tp Time to Peak TRCA Toronto and Region Conservation Authority TSS Total Suspended Solids United States UTM Universal Transverse Mercator VO Visual OTTHYMO Software Suite VO2, VO3, etc. WHPA Wellhead Protection Area XIMP Directly Connected Impervious Area 1 INTRODUCTION The Lake Simcoe Region Conservation Authority s mission is to work with our community to protect and restore the Lake Simcoe watershed by leading research, policy and action.

6 A key component of this is to ensure development is done in an environmentally friendly and sustainable manner. One of the ways this is achieved is through development review. Development review can include the need for the following: (a) Watershed or Sub-watershed Plan and Master Environmental Servicing Plan; (b) Planting or Vegetation Plan, Vegetation Preservation Plan; (c) Watercourse and/or Valley Wall Stabilization Plan; (d) Slope stability-erosion study; (e) Environmental Impact Study (Hydrogeological and or Ecological EIS); (f) Stormwater Management Report; (g) Erosion / Sediment Control Plan; (h) Floodplain Study; (i) Dynamic Shoreline Study; (j) Water Budget, Hydrological and Hydrogeological Studies; (k) Coastal Engineering Study; and (l) Any report or study required by the Conservation Authority to provide explanation/analysis of a specific concern.

7 The purpose of this document is to provide guidance to municipalities, the development community and their consultants regarding the Stormwater Management (SWM) and Erosion / Sediment Control requirements of the Lake Simcoe Region Conservation Authority (LSRCA) in accordance with the Lake Simcoe Protection Plan and Provincial Policy Statement. It is not intended to be a comprehensive Stormwater Management planning and design manual like the SWM manual published by the Ministry of the Environment (MOE, 2003) or similar documents. Detailed planning and design guidance can be found in those documents. The guidance in this document is focused on what should be included in SWM submissions to the LSRCA. It should result in the following benefits: enhanced protection of the natural environment and improved infrastructure resiliency to climate change; designs that better reflect natural hydrology; application of uniform and consistent SWM standards; reduced need for re-submissions due to inadequate information; and streamlined review process and improved client service.

8 2 Environmental Planning and Stormwater Management The MOE SWM manual provides an environmental planning context and shows the relationship with the municipal land use planning process. The environmental planning process includes watershed and subwatershed studies, environmental Management plan or master drainage plan, and the Stormwater Management Report. Urban development should be done in relationship with the environmental planning process. The SWM plan for the urban development, would then follow the environmental criteria developed through the watershed / subwatershed plan to meet its objectives. In some cases where the development is allowed to proceed without subwatershed planning having taken place where little future development is planned, the MOE SWM manual provides some guidance on the environmental design criteria.

9 The Provincial Policy Statement (PPS) (Policy ) and Lake Simcoe Protection Plan (LSPP) identifies Stormwater Management policies for development. These policies must be read in conjunction with local municipal standards and / or watershed / sub-watershed studies in respect of Stormwater quantity and quality control. The LSRCA's requirements for all Stormwater Management submissions are outlined in the following sections, which include a description of LSRCA SWM criteria, guidance on approved methods and techniques, a summary of key hydrologic parameters, modelling and mapping requirements and a summary of submission requirements. For more information on modelling and mapping standards, refer to the 2002 Minitry of Natural Resources (MNR) document entitled Technical Guide, River and Stream Systems: Flooding Hazard Limit.

10 An additional consideration during the environmental planning process is climate change. The Ontario Climate Change Strategy (OCCS, 2015) defines climate change as any significant change in long-term weather patterns. It can apply to any major variation in temperature, wind patterns or precipitation that occurs over time. The OCCS states that extreme weather events such as storms and droughts are becoming more frequent around the world. The OCCS further elaborates that in July 2013, a monumental rainstorm dropped 125 mm of rain in just a few hours over some parts of Ontario, leading to flooding and property damage estimated at $940 million in Toronto alone and states that climate change requires a shift in thinking and behaviour. The OCCS identifies vulnerabilities caused by changing weather patterns in areas such as public safety and emergency response, roads and other infrastructure, buildings and homes that need to be considered.