Thompson Creek Flood Study Report - City of Peterborough

Thompson Creek Detailed Flood Reduction Study
City of Peterborough
2.0 PHASE 1 – PROBLEM OR OPPORTUNITY
2.1 DEFINITION OF STUDY AREA
The study area defined for this Class Environmental Assessment consists of the
Thompson Creek watershed downstream of the Thompson Creek Dam and local
drainage areas between the southern drainage boundary of Thompson Creek and
Parkhill Road East which drain directly into the Otonabee River. These areas are
indicated in Figure 2.1. The Thompson Creek drainage area is approximately
75 hectares. The total area of the local drainage systems is approximately 125 hectares.
2.2 IDENTIFICATION OF THE PROBLEM
There is a long history of flooding in certain areas of the City of Peterborough. The
natural physiography of the area and the historical evolution of the City have resulted in
situations where the both the natural and man-made drainage systems are unable to
safely convey storm runoff during extreme events. The storm of July 2004 was a
dramatic example of this situation where extensive flood damages occurred throughout
the City. Flooding occurred for several reasons: i) water courses overflowed and
flooded adjacent lands; ii) water courses overflowed and spilled flow down the “line of
least resistance” flooding properties in its path; iii) storm sewers surcharged and flow
went down available overland flow routes flooding properties in its path, and iv) storm
and/or sanitary sewers backed up into the basements of properties connected to them.
2.3 PROBLEM STATEMENT
The problems identified above may be present to varying degrees within the Thompson
Creek study area. Defining the magnitude of specific problems was part of the
investigations completed during the current study. However, the general problem
statement can be stated as:
“What are the preferred methods of providing current and future residents of the
Thompson Creek study area with a satisfactory level of protection from the negative
impacts of flooding in an environmentally acceptable manner.”
This problem definition required expansion to identify the specific goals and criteria
that must be met in order to be considered a valid solution to the problem. This was
accomplished once the existing conditions within the study area had been characterized
and a detailed problem list prepared (see Section 4). The criteria for “a satisfactory
level of protection” were defined as part of the city-wide master plan. The detailed
evaluation criteria used are described in Section 5 as a prerequisite of the identification
and evaluation of alternative solutions to the problem.
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