Niagara Peninsula Conservation Authority

Stormwater Management Guidelines

boisTypewritten TextApproved by N.P.C.A. Board on March 17, 2010

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Prepared by:

AECOM202 72 Victoria Street South 519 886 2160 telKitchener, ON, Canada N2G 4Y9 519 886 1697 fax

Project Number:60119867

Date:January, 2010

Water

Niagara Peninsula Conservation Authority

Stormwater Management Guidelines

AECOM Niagara Peninsula Conservation Authority Stormwater Management Policies and Guidelines

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Executive Summary

Introduction

Water is essential for all life. Clean and abundant water is necessary to maintain the health of our naturalenvironment, and ultimately the residents who live there. In partnership with the Niagara Peninsula ConservationAuthority and the Ministry of Environment, the Niagara Region initiated the development of the Niagara WaterQuality Protection Strategy. The goal of the Strategy is to protect and provide for the sustainable use of Niagaraswater resources, and to ensure safe and abundant water for current and future generations.

Since the release of the Niagara Water Quality Protection Strategy, the watershed partners have been workingdiligently on implementing the recommendations and actions identified in the Strategy. This StormwaterManagement Policies and Guidelines document was commissioned as a Direct Action arising out of the NiagaraWater Quality Protection Strategy.

This document is intended to provide a long-term plan to guide the safe and effective management of runoff in urbanand urbanizing areas, while sustaining the health of local rivers and streams. This report will provide detailedstormwater management (SWM), erosion and sediment control policies and criteria for existing and proposeddevelopment in the Niagara Region and the NPCA watershed.

The Stormwater Management Policies and Guidelines document is meant to be used as a companion to localmunicipal stormwater management policies and guidelines. It is not meant to supersede local municipal criteria.Rather, the intent of this document is to attempt to provide a consistent approach to stormwater managementplanning for all municipalities within the NPCA watershed.

This Executive Summary has been prepared to provide an overview of the work completed, as well as a backgroundon SWM. The information has been organized and is presented under the following headings.

Section 1: IntroductionSection 2: OverviewSection 3: BackgroundSection 4: Stormwater 101

Overview

The Stormwater Management Policies and Guidelines report will have an effect on future land use, growth,environmental, and financial objectives. Typically, without SWM, erosion, and sediment controls, urban growth cancontribute to a rise in runoff volumes and peak flows. In turn, this can lead to flooding, degraded water quality andthe destruction of aquatic and terrestrial habitat.

A number of watershed and subwatershed studies have been developed for the Niagara Region and the NPCAwhich will provide guidance on setting SWM, erosion, and sediment control targets. The coverage however is notcomplete and an approach will be required to consolidate the existing information and fill the gaps on an interimbasis as further subwatershed strategies are developed.

It is important to ensure that the Stormwater Management Policies and Guidelines report is developed in a mannerthat will provide input to all municipality initiatives. This could include cost implications to by-law updates, technicalguidance for stormwater design criteria, linkages with the Official Plan Updates, and input to budgets.

AECOM Niagara Peninsula Conservation Authority Stormwater Management Policies and Guidelines

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This report will build on existing information and previous studies, outline the existing policies and criteria, andidentify and evaluate alternative policies and criteria to address current needs and future growth.

What is the Goal?To reduce, and eventually eliminate if possible, the undesirable impacts of stormwater, erosion and sediment on thebuilt and natural environment, re-establish the benefits of precipitation, and protect and enhance water quality in theNiagara Region and the NPCAs water sources that emphasizes environmental, social, and economicconsiderations.

What are the Objectives?Rationalize SWM, erosion and sediment policies and criteria within the municipalities and to develop a uniformstrategy to guide staff and decision-makers in the planning, design, implementation, monitoring and maintenance ofassociated infrastructure and facilities. This will be carried out through the following:

The development of the framework for integrated SWM, erosion, and sediment policies and criteria (principles,goals and objectives, priorities for action, and integration with other plans);The identification of a streamlined, co-ordinated institutional process for delivering SWM, erosion, and sedimentcontrol services (i.e., clarifying roles and mechanisms for external communications and co-operations); andThe development of needed support tools (e.g., SWM erosion, and sediment policies, guidelines, by-laws andimplementation with the Official Plans).

Where is the study area?The study area encompasses the current boundary for the NPCA watersheds, and includes all municipalities lyingwithin and on the NPCA jurisdictional boundary.

What factors are involved in the study?The characterization is broad in scope, and it includes the consideration of all factors influencing SWM, erosion andsediment polices and criteria development. Areas of investigation include:

The policy development process, including a review of current practices, Official Plan policies relating to SWM,and municipal design standards;A review of applicable SWM legislation on a federal, provincial, and municipal level;The framework for Master Drainage Planning including: legislative framework, watershed and subwatershedplanning, the Environmental Management Plan, Master Drainage Plans and studies, Adaptive EnvironmentalManagement and monitoring plans, and SWM retrofit studies;SWM opportunities and constraints related to development types (e.g., greenfield, brownfield, and greyfielddevelopment, redevelopment and infilling, and existing development);SWM requirements including relevant existing watershed and subwatershed plans, water quality (surface andgroundwater), and water quantity;Hydrologic and hydraulic analysis including model and parameter selection, storm event duration and climateand rainfall data;SWM BMPs for at source controls, conveyance controls, and end-of-pipe, as well as site analysis for BMPconsideration, treatment train evaluation of performance, and typical performance standards for BMPs;SWM facility design guidelines;Construction and sediment control requirements;Report submission requirements;The approval process;Monitoring and maintenance before, during and post construction;

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SWM system funding; andRecommended policies and criteria, including by-laws.

Background

SWM implementation for an urban area is applied directly through the built infrastructure. The planning objectivesfor this study focus on a process that will allow the proponent to identify, protect and preserve natural features, andconsider their functional role in SWM planning. It includes:

At source controls at the lot level to reduce runoff and reduce pollutants entering into the drainage system;Conveyance controls, such as grassed swales, roadside ditches and pervious pipes to reduce flows and removepollutants;End-of-pipe controls to control flows and remove pollutants prior to stormwater entering the receiving systemsuch as streams on other water bodies;Best available practices while integrating or enhancing existing natural features into the system;Identification of a review process that ensures all agencies the opportunity to review and comment on SWMreports and planning; andReflection and incorporation of the SWM objectives set out in current OPs, existing watershed andsubwatershed planning, and Master Drainage Planning, especially regarding flood protection, erosion andprotection of the receiving natural environment

The intent of SWM planning is to mitigate the impacts that urbanization has on natural drainage systems such aschanges to runoff, flow, water quality, erosion and sedimentation characteristics. Generally however,predevelopment conditions are not natural and use is typically under agricultural land use. That is why the goalsand objectives in a watershed or subwatershed strategy typically are based upon environmental goals that arejudged to be acceptable to the community and society as a whole and are achievable given existing conditions.Regardless, the SWM planning is developed to provide a design on how the stormwater drainage and managementstructure is to be built to meet accepted goals.

Can the problem be completely solved?The urban landform is a major stressor on infrastructure and environmental conditions. As well, where developmentoccurs and how developments are planned and built have very significant effects on this issue. Imperviousnessrepresents the imprint of land development on the landscape. Increased impervious area results in changes inbaseflow, peak flow, and total runoff volume. Therefore, current and future conditions have to be acknowledged inevery SWM Strategy.

Stormwater 101

Urban Runoff Pollution

What is the Problem?Urban land uses generate residual