Don Mills Channel Flood Reduction

Don Mills

As part of Markham’s Flood Control Program, a Class Environmental Assessment was initiated on the Don Mills Channel.

The Don Mills Channel is a small man made channel that runs through the commercial / industrial area in the Woodbine Avenue and Denison Street area.

Several of the private properties and roads in this area are prone to flooding during large storm events.

The environmental assessment aims to:

  • Identify and understand the causes of flooding in the study area
  • Develop a range of alternative solutions to reduce flooding and flood damages from the Don Mills Channel
  • Recommend the preferred solution or suite of solutions to best reduce flooding and flood damage
  • Establish the funding, approvals and other activities needed to implement  the recommended solutions.
  • The Study Objective is to provide flood protection for a Council Approved 5 year Level of Protection for the Don
  • Mills Channel Area, as per the following Council Resolution (February 2013):

That the City's flood control strategy adopt a 5 year level of service target for Don Mills Channel drainage system based on its original design and consider other options, subject to technical feasibility and approval as part of a future Class EA;

The current system of open channels and culverts does not have adequate capacity to handle storm water runoff during large storm events. Businesses surrounding the Don Mills Channel have flooded numerous times since the land was developed in the 1970’s. Major roads in the study area, including Woodbine Avenue, can be impassable during severe storms.

The Don Mills Channel study area was realigned and confined to a relatively narrow channel corridor through urban development. Significant portions of the Don Mills Channel were also piped through some of the older development sites in the study area.


Don Mills Flood Reduction Schedule

Winter / Spring 2016

  • Notice of Study Commencement
  • Existing Conditions Inventory and Analysis

Fall 2016

  • Liaison committee meeting with key stakeholders to review existing conditions
  • Public Information Centre (PIC) #1

Spring / Summer 2017

  • Development of initial flood reduction alternatives
  • City / Agency Technical Consultation Process

Spring 2018

  • Liaison committee meeting with key stakeholders to review preliminary preferred alternative
  • Public Information Centre #2

Class EA Phase 1

Identify Problem or Opportunity

  • Identify Need
  • Initiate Consultation with the public and agencies
  • Notice of Commencement

Background Review

  • Obtain and review background documentation and initiate agency contact
  • Identify data gaps to be address during the site inventory/ investigation

Class EA Phase 2

Site Inventory / Investigation

  • Undertake natural heritage investigations
  • Aquatic habitat assessment
  • Incidental wildlife survey
  • Undertake hydrology/hydraulics investigation
  • Archealogical Investigations
  • Identify opportunities and constraints
  • PIC #1

Evaluation of Alternatives

  • Identify alternatives
  • Complete impact assessments
  • Evaluate alternatives
  • Select preferred alternative

Preliminary Design / Project File Report

  • Preliminary design of preferred alternative
  • Recommendation for further study, if required
  • PIC# 2
  • Develop a  staging and implementation plan
  • Prepare Project File Report
  • Notice of Completion
  • 30-day Public Review
  • Implementation

Detailed Design / Implementation

  • Detailed design of the proposed works
  • Obtain permits and approvals
  • Prepare contract drawings and tender documents
  • Construction and operation of the works
  • Post-construction monitoring

View a detailed Class EA Process for municipal infrastructure projects.