Landscape Design Guide for Low Impact Development
Total Page:16
File Type:pdf, Size:1020Kb
APPENDIX B – LANDSCAPE DESIGN GUIDE FOR LOW IMPACT DEVELOPMENT APPENDIX B LANDSCAPE DESIGN GUIDE FOR LOW IMPACT DEVELOPMENT VERSION 1.0 June 2010 NOTICE The contents of this report do not necessarily represent the policies of the supporting agencies, although every reasonable effort has been made to ensure the integrity of the report. The supporting agencies do not make any warranty of representation, express or implied, with respect to the accuracy or completeness of the information contained herein. Mention of trade names or commercial products does not constitute endorsement or recommendation of those products. ACKNOWLEDGEMENTS Project Team: • Dougan and Associates • CVC Staff: Christine Zimmer, Susan Mentis, Paul Tripodo, Robb Lukes Reviewing Organizations: • Brodie & Associates Landscape Architects, Inc • City of Brampton • City of Mississauga • Credit Valley Conservation • Schollen & Company International, Inc. • Toronto Region Conservation Authority • Town of Halton Hills • Town of Orangeville Funding support for this document was generously provided by: • Region of Peel • Credit Valley Conservation PUBLICATION INFORMATION Comments on this document should be directed to: Robb Lukes, MSc Water Resources Specialist Credit Valley Conservation Authority 1255 Old Derry Road Mississauga, Ontario, L5N 6R4 Tel: (905)-670-1615 ext 414 Email: [email protected] LID Landscape Design Guide Version 1.0 – June 2010 page 1 TABLE OF CONTENTS 1 INTRODUCTION 4 1.1 ABOUT THIS DOCUMENT ................................................................................. 4 1.2 LANDSCAPING PRINCIPLES FOR SUCCESSFUL LID PRACTICE ............................ 5 1.3 PROFESSIONAL ROLE: ...................................................................................... 6 1.4 LANDOWNER PERCEPTIONS: ............................................................................ 4 2 GENERAL GUIDANCE 8 2.1 LID DESIGN AESTHETICS .................................................................................. 8 2.1.1 FUNCTION OF PLANTS ..................................................................... 9 2.2 ASSESSING SITE CONDITIONS ...................................................................... 10 2.2.1 CLIMATE ............................................................................................. 10 2.2.2 SOILS ................................................................................................... 11 2.2.3 MOISTURE .......................................................................................... 12 2.2.4 SALT & POLLUTANTS ...................................................................... 13 2.2.5 DISTURBANCE EVENTS & NATURAL PROCESSES ................. 13 2.3 SELECTION OF PLANTS .................................................................................. 14 2.3.1 NATIVE, INTRODUCED & RARE PLANTS ................................... 14 2.3.2 PLANT CHARACTERISTICS............................................................ 17 2.3.3 SUPPLY ISSUES ............................................................................... 20 2.4 LANDSCAPING MATERIALS ............................................................................ 21 2.4.1 SOILS ................................................................................................... 21 2.4.2 MULCH ................................................................................................. 21 2.5 PLANTING PLANS & SPECIFICATIONS ............................................................ 24 2.6 CONSTRUCTION ............................................................................................. 25 2.6.1 SITE PREPARATION ........................................................................ 25 2.6.2 INSTALLATION .................................................................................. 25 2.7 MAINTENANCE .............................................................................................. 26 2.7.1 PLANT SUCCESSION & WEED CONTROL .................................. 28 2.7.2 NUTRIENT MANAGMENT ................................................................ 29 2.7.3 WILDLIFE ISSUES ............................................................................. 29 3 INDIVIDUAL LID PRACTICE PLANTING GUIDANCE 30 3.1 GREEN ROOFS................................................................................................ 30 3.1.1 GREEN ROOF PLANT LIST ............................................................. 33 3.2 BIORETENTION ............................................................................................... 35 3.2.1 BIORETENTION CELLS ................................................................... 35 3.2.2 EXTENDED TREE PITS .................................................................... 40 3.2.3 STORMWATER PLANTERS............................................................. 44 3.2.5 RAIN GARDENS ................................................................................. 47 3.2.6 CURB EXTENSIONS ......................................................................... 50 3.2.7 BIORETENTION PLANT LIST .......................................................... 55 3.3 FILTER STRIPS .................................................................................................. 52 3.3.1 FILTER STRIP PLANT LIST ............................................................. 65 3.4 ENHANCED GRASS SWALES .......................................................................... 68 3.4.1 ENHANCED GRASS SWALES PLANT LIST ................................. 72 3.5 DRY SWALES .................................................................................................. 74 3.5.1 DRY SWALE PLANT LIST ................................................................ 80 4 MASTER LID PRACTICE PLANT LIST 83 LID Landscape Design Guide Version 1.0 – June 2010 page 2 5 REFERENCES 95 LID Landscape Design Guide Version 1.0 – June 2010 page 3 1 INTRODUCTION In recent years the development of innovative treatment and retention practices for stormwater has matured. Traditionally, stormwater management has been an end-of- pipe practice located on public property and maintained by public agencies. However, low impact development (LID) is fundamentally different because it is intended to treat stormwater runoff at the source. LID practices are predominately located on private property or within the right-of-way and will be primarily maintained by the property owner. LID is also different because many of the practices have an integral vegetated component which supports the treatment, evapotranspiration and infiltration functions. Thus, the plant selection and design are essential both for function and for the public perception and acceptance of LID practices in the landscape. 1.1 ABOUT THIS DOCUMENT This document – the Planting Guide for Enhancing LID Measures – has been developed by Credit Valley Conservation (CVC) in consultation with the Toronto and Region Conservation Authority (TRCA) and member municipalities. It is intended to be an appendix to the Low Impact Development Stormwater Management Planning and Design Guide (LID Guide), providing support related to the plant selection and design of LID landscape. The LID Landscape Design Guide complements the LID Guide by providing land managers and professional practitioners with an understanding of the guiding principles of LID planting design, implementation and management. While useful for the facilities and locations described herein, these guidelines may not be suitable for natural SWM approaches (i.e. natural channel design, floodplain storage or wetland applications) or in locations outside of CVC and TRCA jurisdictions. The practitioner must respect local bylaws and standards, agency requirements and applicable legislation. Plant species recommendations are targeted for the greatest performance in the CVC and TRCA jurisdictions. In this document you will find: In Section 1 – The principles to guide landscaping with LID, and the value of landscape design and the role of native and introduced plants. In Section 2 – General guidelines for the landscaping design of LID practices, including planting standards, general site conditions, fundamentals of plant selection, direction for construction and planting, and for maintenance and monitoring. In Section 3 – Planting guidelines that are customized to each individual LID practice identified in the LID SWM Manual, including a plant species list. In Section 4 – A master LID plant list with plant characteristics identified. LID Landscape Design Guide Version 1.0 – June 2010 page 4 1.2 LANDSCAPING PRINCIPLES FOR SUCCESSFUL LID DESIGN Today’s urban environments require a new vision, one that is effective at improving the health of communities and watersheds through innovative landscape management and design. Studies have found that landowners and the general public alike will respond positively to LID practices when they respond to the following principles: Collective Vision All residents, businesses and landowners in a city benefit from the environmental quality and aesthetics of the area in which they live and work. LID practices of a variety of scales are suited to both small residential sites as well as large private and public spaces. Each setting presents a unique opportunity to provide an environmental benefit while beautifying the space through appropriate landscaping and design. When viewed collectively at the city or watershed scale, integrated landscape projects will produce a measurable improvement to