By Stephen Mitchell, C.E.T.
Corm Construction
Sewer & Watermain Ltd.
Micro-ponds at the Cane Parkway Stormwater Quality Treatment Facility.
Accurate grading during construction
should never be
taken for granted, even when
constructing a stormwater
quality, (end-of-pipe) facility where
water flow and drainage remain critical
design elements.
Because of the unique design and
challenging construction activities associated
with the Cane Parkway Stormwater
Management Facility in Newmarket,
Ontario, Corm Construction decided
to use its own resources for construction
surveying, since grade setting
and checking would be an ongoing service
requiring immediate use of equipment
at any given time. The window for
construction was limited, and the contractor
had little opportunity in the construction
schedule to depend upon outside
geomatics services. Since the
project was located adjacent to an existing
wetland and within the regulated
floodplain of the Holland River, there
was no room for grading errors that may
cause delays.
Hydraulic grade-line was of greatest
concern to the consulting engineer,
Cumming Cockburn Limited, due to the
closeness to outlet to river. Cumming
Cockburn was hired by the Town of
Newmarket Public Works and Environmental
Services Department, in conjunction
with the Lake Simcoe Region
Conservation Authority, to prepare the
detailed engineering design and Holland
River walkway extension and improvement.
The walkway improvement included
installation of two new 30,000
lb footbridges that can accommodate
maintenance vehicle access to the site.
The challenge to the consulting engineer
was to achieve maximum storage
in the wet pond within design parameters
governed by the existing hydraulic
grade line.
The Cane Parkway Stormwater management
facility is a hybrid facility consisting
of a flow splitter, a sediment
forebay, a wet pond, and a constructed
wetland with micro-pools and submerged
outlet culvert. Located immediately
west of the Municipal Office on
Mulock Drive, the facility and walkway
system provides a focal point in the community.
The hybrid facility is also adjacent
to the 900 mm diameter York-Durham
sanitary forcemain that influenced
the facility design in the vicinity of the
constructed wetland and pools. Not only
does the facility improve water quality
treatment for the 102 hectares of developed
urban land immediately upstream,
it also improves the quality of the Holland
River ecosystem. All interested
parties supported the project and had
opportunity to contribute to the design
of the facility through a “Schedule B”
Class Environmental Assessment.
Constructed at a cost
of $430,000, the hybrid facility is functioning
as designed, within a critical
hydraulic grade line of approximately
one metre.
Abridged
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