HomeMy WebLinkAboutEnv - Strasburg Creek North Branch Environmental Assessment - Ponds 65, 66 & 61Date:March 9, 2011
To:Environmental Committee
From:Diana Lupsa P.Eng., Design and Construction Project Manager
cc:Steve Allen P.Eng., Manger Design and Approvals
Subject:MUNICIPAL CLASS ENVIRONMENTAL ASSESSMENT -Strasburg Creek
(North Branch) -Schedule B Class EA – Ponds 65, 66 & 61
1. BACKGROUND
The North Branch of Strasburg Creek within the Huron Business Park has experienced
significant alterations to both form and function of the system as a result of development
pressures, historic works and wildlife management issues, and as a result is not achieving the
management objectives (i.e. water quality controls and baseflow enhancement) as outlined in
previous works by the City of Kitchener, the GRCA and others.
In 2010, the City of Kitchener Stormwater Management Facility Retrofit, Class EA Report
(Schedule A+) was completed by Aquafor Beech Limited with support from the Federal and
Provincial governments as part of the Economic Action Plan Investments in Ontario and the
Infrastructure Stimulus Fund. A key recommendation of the 2010 EA report, in regards to ponds
61 and 65, included that the Class EA Schedule should be revised from a Schedule A+ to a
Schedule B in order to appropriately evaluate and manage the existing environmental conditions
and future considerations. To allow for a broader, more holistic approach for the improvement of
the north Branch, Pond 66 was added to the study in addition to the respective connecting
channels (see Figure 1.Overview of study area and location of reaches along Strasburg Creek).
Pond 65
Reach 1
Reach 2
Reach 3Reach 4
Pond 66
Pond 61
Figure 1. Overview of study area and location of reaches along Strasburg Creek
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2. STUDY OBJECTIVE
The overall objective of this Class EA is to select a preferred design alternative for each of the
three existing stormwater management facilities and the respective connecting channels with
the goal of improving water quality within the North Branch of the Strasburg Creek Watershed.
Additional objectives include the improvement/restoration of local aquatic and terrestrial habitat,
the removal of fish barriers, improvement of baseflow and instream temperature regimes, the
improvement of future operations and maintenance activities and the retrofit of existing concrete
channels so as to represent a more natural stream channel design.
3. PROBLEM IDENTIFICATION
Five (5) areas of concern were identified:
1. Poor Water Quality – due to no water quality control within the study area, on-line ponds,
concrete lined connecting channels, erosion issues and lack of riparian buffers and
shading;
2. Loss of baseflow - due to high impervious levels of surrounding lands as well as
concrete bed and bank treatments within connecting channels;
3. The lack of fish habitat features – lack of diverse channels features, loss of continuity of
flow and the presence of fish barriers;
4. Degradation of terrestrial vegetation features - as a result of ongoing beaver activities,
development pressures and infrastructure failures; and
5. Erosion - Ongoing erosion in the upstream channel of Pond 61, resulting in potential
risks to the adjacent private property.
4. PREFERRED SOLUTION – PONDS
The evaluation of the alternatives was based on the study objectives, the established technical
considerations and criterion under the general categories of Physical/ Natural Environment,
Social/ Cultural, Economic criteria and Technical/Engineering criteria.
Upon application of the established criteria, the preferred alternatives for the three existing
SWM facilities include:
Pond 61 – Alternative No 5.– Full Retrofit: Channel Bypass (Creation of an off-line
facility)
Pond 65 – Alternative No 4. –Bypass Channel and Selective Works (Creation of an off-
line facility)
Pond 66 – Alternative No 3. – Wetland Restoration
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5. PREFERRED SOLUTION – CHANNELS
Due to the interconnected nature of the ponds and channels reaches, the preferred alternatives
for the respective channel reaches will be evaluated and confirmed once the preferred options
for the three ponds have been confirmed through agency consultation.
The four alternatives for the respective channel reaches 1-4 include:
Do Nothing
1.– no restoration measures would be undertaken except on an emergency basis;
Selective Works
2.- undertaking works at strategic locations in the reach. This would involve
removing fish barriers in selected areas to improve fish passage;
. Geomorphic Referenced River Engineering (GRRE) -
3involve complete restoration and
minor realignment of the channel using stable stone works, in addition to natural stone and bio-
engineering; and
Natural Channel Design -
4.realigning the stream channel such that it follows a natural
alignment. Restoration of the stream channel would be implemented using natural material (i.e.:
river run stone, native plant species).
The objective of the channel restoration works in regards to the channel reaches would in
general include the following:
Channel to remain as is upstream on Pond 65 (Reach 1);
To naturalize the concrete lined channels (Reach 2 & 3) ; and
To restore the existing natural channel upstream of Pond 61 (Reach 4) and include
erosion control measures;
6. NET ENVIRONMENTAL BENEFIT
The net environmental benefits of the proposed preferred solutions include:
The retrofit of two (2) existing water quantity SWM facilities (Pond 65 and 61) to include
water quality control, and the restoration of the historic wetland at Pond 66.
Water quality control for 79 ha of high impervious land-use (previously no water quality
control);
Removal of the downstream fish barrier at Pond 61 (currently the pond has a bottom
draw outlet);
Creation of 1.3 km of continuous stream channel using natural channel design
principles;
Removal of 430m of concrete lined channel resulting in the improvement of baseflow
conditions within the surface drainage system
Restoration of approximately 700m of riparian area;
Naturalized landscape of approximately 2 ha of land. Configuration and species
incorporated into planting to achieve wildlife management objectives (i.e. Canada Geese
and Beaver populations) and to promote to the extent possible habitat conditions for
other species;
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Restoration of flood control capabilities and permanent pool volumes at ponds 61, 66
and 65, including the removal of more than 6500m3 of accumulated sediments;
Removal of invasive vegetation (Phragmites australis); and
Restoration of riparian buffer communities and the naturalized landscape plantings are
anticipated to result in the improvement in the overall North Branch temperature regime.
7. ESTIMATED COST
The anticipated overall cost of the preferred alternatives for the retrofit of the three ponds is
$3,369,000 (2011 dollars). The approximate overall cost of the remediation/enhancement of the
respective interconnecting reaches is $ 975,000 to 1,250,000 (2011 dollars). These costs
estimates are based on the preliminary design.
8. NEXT STEPS
The next steps associated with this Class Environmental Assessment include the detailed
design for the retrofit of the three existing SWM ponds and the conceptual design of the
respective interconnecting channels based on the preferred alternatives. In addition, this study
will include the development of an implementation strategy for all works, with a focus on
environmental impact mitigation, construction staging and general timing. The timeline for
implementing these projects is based on the City’s capital budget. As it currently stands, the
earliest City of Kitchener could move to address these projects would be around 2014.
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