Chapter A - Introduction - City of Pickering

COMMENT MESPA RESPONSE (December 2011) CITY RESPONSE (October 2012) RESPONSE
Liner Required
According to the information provided, 59 of the 69 ponds will require a
liner. In some instances the function of the liner is to maintain a
permanent pool whereas in the majority of the cases the purpose is to
prevent groundwater migrating into the pond. In either case, a liner
introduces concerns with respect to the long-term operations and
maintenance of the facility as the liner affects whether the pond is
functioning as designed. Furthermore, for ponds constructed within the
groundwater table perimeter drains may be required to relieve the uplift
pressure on the pond.
The requirement for these drains and liners introduces an additional
operations and maintenance requirement as they must be functioning for
the proper operations and maintenance of the pond. The cost-analysis
completed for the stormwater scheme should include several scenarios to
account for how this will be dealt with ranging from requiring full
replacement of the liner and perimeter drains at every cleanout to
alternative structural measures to ensure the liner is not damaged during
cleanout operations.
The need for liners in SWM ponds has been reviewed in
re-evaluating the SWM Matrices. Since this is a very site
specific issue, the need for a liner at specific ponds has
been deferred to the NFSSR stage when more detailed
site investigations are completed at each pond location.
Based on the revised modelling, the use of unlined
SWMFs appears to significantly mitigate the impact of
development.
The cost analysis for the SWMFs will be completed as
part of the NFSSRs as per the agreed upon Terms of
Reference.
City staff have no objections to deferring the
requirements for pond liners to the NFSSR’s,
but will be looking specifically, at the subject
from an operations and maintenance
perspective (i.e., ensure City staff have the
ability to draw down the pond), while minimizing
maintenance costs.
In addition City staff would like to note that if a
permanent “Permit to Take Water” (i.e. long
term groundwater control) , is required, than an
alternative pond location will be required.
Each of the SWMF designs will be
supported by a geotechnical assessment
that will address the need for liners as well
as the need for construction dewatering.
Only pumping that exceeds 50,000 L/day
will require a Permit to Take Water (PTTW)
from the MOE. Should groundwater control
be needed at a pond location, it is expected
that this control will be a small amount of
under-liner drainage control. Pond and
under-liner design will preclude the need for
long term active pumping that would be
subject to PTTW requirements.
REPORT CHAPTER
AND SECTION
Chapter B6.4
Chapter B4.3.7
Notwithstanding the provision of liners, where there is a higher potential
for spills, such as on Arterial Roads and industrial areas, stormwater
ponds should not be located within the groundwater table as the potential
for contamination exists. Furthermore, by building stormwater
management facilities in the water table, the proponent is introducing the
potential for contamination of the groundwater table which contradicts the
policies in CPDP.
PTTW Required
While the requirement for a PTTW can only be confirmed when more
detailed information is available, this was flagged as a potential issue at
Ponds 8, 15, 16, 24, 36, 43 and 46A. Given that extensive dewatering will
be required to construct these facilities, and likely in the long-term to
control groundwater levels, alternative pond locations should be provided
for these locations.
Although some dewatering may be needed for facility
construction, it cannot be confirmed that long term
groundwater control is needed at this time. This will be a
function of site specific conditions, and the type of
facility being constructed. This will be assessed at the
NFSSR stage or detailed design stage.
Please see comment above.
Each of the SWMF designs will be
supported by a geotechnical assessment
that will address the need for liners as well
as the need for construction dewatering.
Only pumping that exceeds 50,000 L/day
will require a Permit to Take Water (PTTW)
from the MOE. Should groundwater control
be needed at a pond location, it is expected
that this control will be a small amount of
under-liner drainage control. Pond and
under-liner design will preclude the need for
long term active pumping that would be
subject to PTTW requirements.
Chapter B4.3.7
Adjacent to Durham ROW
Until the final alignment of the roads in the Region’s Class EA for
Regional Services has been set, there will need to be flexibility in the
location of ponds. Given that, 22 of the 69 pond locations may be affected
by the alignment of Regional roads. A note has been made in the table
when the draft alignment appears to affect the pond block.
Noted
City staff has also noted facilities which have
Regional infrastructure (sanitary sewers/water
mains) proposed adjacent to, or within the
proposed pond block.
City staff would like the SLG to provide
Comment regarding potential conflicts with
ponds and infrastructure has been added to
Chapter D3.0.
Chapter D.3.0.
The Sernas Group Inc., Stonybrook Consulting Inc. December 2011, Revised February 2013 Master Environmental Servicing Plan - Amendment
SPL Beatty, Bird and Hale Limited, Earthfx Inc. 07161 Seaton Community, City of Pickering
AMEC Earth & Environmental, R.J. Burnside Appendix A7 – Page 14
Amos Environment + Planning