HomeMy WebLinkAboutENG 01-17�'�� ��`
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From: Richard Holborn
Director, Engineering Services
Report to
Executive Committee
Report Number: ENG 01-17
Date: January 9, 2017
Subject: Pickering City Centre
- Stormwater Management Strategy
File: A-1440
Recommendation:
1. That Council endorse the Pickering City Centre Stormwater Management Strategy Final
Report, April 2015;
2. That Staff be authorized to use the stormwater management criteria that is contained in the
Strategy when reviewing development applications for areas within the Pickering City
Centre;
3. That Council endorse the site specific criteria for Pickering Town Centre Lands (Section 6.2
of the Strategy) to the effect that any redevelopment in the flood storage area on the south
parking lot of the Pickering Town Centre preserve the existing flood storage volume on the
site and that new development in the existing flood storage area be adequately flood proofed
to the predicted 100 year level; and
4. That the appropriate City ofFicials be authorized to take the necessary actions as indicated in
this report.
Executive Summary: The Municipal Infrastructure Group (TMIG) was retained by the City to
undertake the Pickering City Centre Stormwater Management Strategy corresponding to the
vision for the Pickering City Centre area. The Strategy was also initiated in conjunction with the
Krosno Creek Flood Reduction Study Environmental Assessment (EA) and the models, analyses,
and recommendations of that Study have been applied and considered in the development of the
Stormwater Managemenf Strategy for the Pickering City Centre. Within the redevelopment context
needed to achieve the vision for Pickering City Centre, the objective of the Stormwater
Management Strategy was to target enhancement ra�her than maintenance of existing conditions,
given the complex downstream flooding and erosion concerns that exist in the Krosno Creek
watershed.
Implementation of the stormwater management criteria for the redevelopment of the Pickering City
Centre will ultimately reduce peak flow rates and total runoff volume, which will translate inta
greater reductions in flooding and flood damage along Krosno Creek south of Highway 401, as
well as greater reductions in pollutant loadings and erosion potentiaL
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ENG 01-17
Subject: Pickering City Centre
Stormwater Management Strategy
January 9, 2017
Page 2
The Stormwater Management Strategy for the Pickering City Centre also recommends site
specific criferia that any redevelopment in the flood storage area of the south parking lot of the
Pickering Town Centre preserve the existing flood storage volume on the site, and that new
development in the existing flood storage area be adequately flood proofed. If the existing flood
storage was removed altogether, peak flow rates in the flood prone reaches of Krosno Creek
south of Bayly Street would increase and the maximum water level on the upstream side of
Highway 401 would increase, potentially causing damage to structures and property.
Financial Implications: There are no direct financial implications to the City on endorsing the
Pickering City Centre Stormwate.r Management Strategy, however, through adherence to this
strategy in the review of future development applications and subsequent detailed designs,
reductions to flooding within the Krosno Creek watershed, reduction in downstream erosion and
an increase in water quality will be realized.
Discussion: The Pickering City Centre was identified as an Urban Growth Centre in
the Growth Plan for the Greater Golden Horseshoe. The Downtown Pickering - A Vision for
Intensification and Framework for Investment was endorsed in principle by Council on July 8,
2013 (PLN 10-13, Resolution #87/13) and articulates the desired form of redevelopment that the
City would like to achieve. TMIG was retained following the acceptance of the proposal for RFP 8-
12 at tlie November 12, 2012 Council meeting (CS 49-12, Resolution #140/12) to establish a
Stormwater Management Strategy corresponding to the vision forthe Pickering City Centre area.
The majority of the Pickering City Centre drains to Krosno Creek and typically, development within
the area pre-dates the adoption of modern stormwater quantity and quality controls. As such, the
Stormwater Management Strategy for Pickering City Centre was undertaken in parallel with the
Krosno Creek Flood Reduction Study EA (formerly known as the Downtown Stormwater
Management and Diversion Study), which established the most effective means of protecting
people and property from the existing flooding problems in the Krosno Creek watershed. The
models, analyses, and recommendations of the Krosno Creek Flood Reduction Study EA have
been applied and considered in the development of the Stormwater Management Strategy for the
Pickering City Centre.
Four atternatives were modelled and evaluated to determine the most effective stormwater
management criteria for the Pickering City Centre.
Alternatives associated with stormwater management speak to the measures that need to be put
in place to manage the quantity, quality, erosion, and water balance impact of development, often
in an effort to maintain existing conditions. However, within the redevelopment conte� needed to
achieve the vision for Pickering City Centre, the objective of the Stormwater Management
Strategy was to target enhancement rather than maintenance of existing conditions, given the
complex downstream flooding and erosion concerns that exist in the Krosno Creek watershed.
Four alternatives were modelled and evaluated to determine the most effective stormwater
management criteria. The differences between the evaluated alternatives consisted of various
fevels of volume control, as well as adopting a pre-development runoff coefficient of 0.50, which is
CORP0227-07/01 revised
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ENG 01-17
Subject: Pickering City Centre
Stormwater Management Strategy
January 9, 2017
Page 3
consistent with the City of Toronto Wet Weather Flow Management Master Plan (2006) and the
City of Ottawa Sewer Design Guidelines (2012), and eliminates the subjectivity of pre-
development conditions. The stormwater management criteria that was selected for the Pickering
City Centre is noted below:
Control of post-development peak flows to pre-development levels for the 2 through 100 year
storm events, with an assumed maximum pre-development runoff coefficient of 0.50;
Volume control via low impact development facilities to achieve a runoff retention target of 5
mm; and,
Water quality treatment to achieve the TRCA/MOECC requirement of 80% total suspended
solids removal.
Implementation of the above-noted stormwater management criteria for the redevelopment of the
Pickering City Centre will ultimately reduce peak flow rates by approximately 7% and total runoff
volume by approximately 18% to 13%, for the 2 year through 100 year storm events, respectively.
These reductions are considerable when comparison is made to maintaining only existing
conditions and will translate into greater reductions in flooding and fload damage along Krosno
Creek south of Highway 401, as well as greater reductions in pollutant loadings and erosion
potential.
The Stormwater Management Strategy for the Pickering City Centre recommends site
specific criteria that any redevelopment in the flood storage area of the south parking lot of
the Pickering Town Centre preserve the existing flood storage volume on the site and that
new development in the existing flood storage area be adequately flood proofed to the
predicted 100 year level.
The entire Krosno Creek watershed north of Highway 401 drains to the single concrete. box culvert
under Highway 401, which is directly connected to a pair of culverts under the CNR tracks. These
culverts significantly restrict the flow that drains to Krosno Creek and contributes to high flood
levels upstream of Highway 401. The Pickering Town Centre is serviced by the trunk storm sewer
system running just west of Glenanna Road (within the Pickering Town Centre property), which
also conveys flows from the upstream residential neighbourhoods.
In the early 1980's the City of Pickering was undertaking a City-wide master plan for stormwater
management (Simcoe Engineering, 1984), which initially identified the need for 20,000 m3 of flood
storage in the area upstream of the Highway 401 culvert, to limit the flows to the capacity of the
CNR culverts and downstream concrete-lined channel. However, prior to the finalization of the
master plan, construction had commenced on an expansion to the Pickering Town Centre
(previously Sheridan Mall, by JDS Investments). The 1984 study states that the City worked with
the developers of the �nall to re-design the south parking lot to create approximately 12,350 m3 of
flood storage. This was determined to be sufficient for the purposes of managing flood risk and
maintaining the downstream drainage regime.
Without special consideration, new development in the existing south parking lot at the Pickering
Town Centre could consume the current flood storage volume. If the existing flood storage was
CORP0227-07/01 revised
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ENG 01-17
Subject: Pickering City Centre
Stormwater Management Strategy
January 9, 2017
Page 4
removed altogether, peak flow rates in the flood prone reaches of Krosno Creek south of Bayly
Street would increase by up to 7% during the 100 year storm. More significantly, the maximum
water level on the upstream side of Highway 401 would increase by 0.61 m during a 100 year
storm, causing damage to structures and property.
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Amendment 26 to the Pickering Official Plan (OPA 26) affected a number of policy sections of the
Official Plan and included new City Centre Neighbourhood policies on various items, including
Stormwater Management. As noted in the Report to Planning & Development Committee PLN14-
14 (Resolution #260/14), after reviewing the preliminary recommendations from the Downtown
Stormwater Management and Diversion Study (now known as the Krosno Creek Flood Reduction
Study and the City Centre Stormwater Management Strategy, respectively), a new policy, 11.10K
(c) (vi) was added. This new policy supported the use of Holding provisions and require where
necessary, proponents to enter into agreements with the City, respecting various development
related matters. It also required the preparation of a comprehensive functional servicing and
stormwater management plan that addresses stormwater management and replacement flood
storage on the Pickering Town Centre site.
In addition to the above, policy 11.10J also recognized the need to implement stringent
stormwater management criteria to assist with downstream erosion control, water quality control
and flooding, and requires stormwater management reports in support of new development to
demonstrate achievement of the objecfives of the Pickering City Centre Stormwater Management
Strategy.
It is recommended that City Council endorse the site specific criteria for Pickering Town Centre
Lands that any redevelopment in the flood storage area of the south parking lot of the Pickering
Town Centre preserve the existing flood storage volume on the site and that new development in
the existing flood storage area be adequately flood proofed to the predicted 100 year flood level.
The Pickering Town Centre owners have been advised through their property management
company, 20Vic Development, that this report is being brought forward to City Council.
It is further recommended that the City Centre Stormwater Management Strategy be endorsed by
Council and staff be authorized to use the stormwater management criteria that is contained in the
Strategy when reviewing development applications for areas within the Pickering City Centre.
.
1. Location Map — Pickering City Centre
2. Pickering City Centre — Stormwater Management Strategy
CORP0227-07/01 revised
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ENG 01-17
Subject: Pickering City Centre
Stormwater Management Strategy
Prepared By:
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Marilee Gadzovski, M.Sc.(Eng.), P.Eng.
Division Head, Water Resources &
Development Services
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Recommended for the consideration
of Pickering City, Council
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Tony Prevedel, P.Eng.
Chief Administrative Officer
CORP0227-07/01 revised
2�
January 9, 2017
Approved/Endorsed By:
,
Rich rd Holbo n, P.Eng.
Director; Engineering Services
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PICKERING CITY CENTRE
Stormwater Management
Strategy
CITY OF PICKERWG • FfNAL REPORT � APRIL 2015
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Prepared on behalf of:
THE CITY OF PICKERING
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Pickering ON L1V6K7
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Pickering City Centre
STORMWATER MANAGEMENTSTRATEGY
CITY OF PICKERING
FINAL � APRIL 2015
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The Municipai infrastructure Group was retained by the City of Pickering to esfablish
a Stormwater Management Strategy to complement the re-development and
intensification of the Pickering City Centre envisioned in the report Downtown
Pickering — A Vision for lntensification and Framework for lnvestment (Urban
Strategies, June 2013).
A number of alternative stormwater management strategies were analyzed and
evaluated in the development of the sfrategy, ranging from business as usual
(adopting current formalized criteria) to widespread and intensive application of
emerging low-impact-development practices to significantly improve water quality,
erosion and flooding conditions in Krosno Creek, to which the majority of the study
area drains.
The recommerided Stormwater Management Strategy includes the following criteria
and recommendations:
i■ Control of post-development peak fl�wr rates to pre-development levels. A
� ' maxirr�um r�noff coefficient of 0.5 should be used to represent pre-
developmenfi conditions, regardless of haw rnuch impe�rious cover
' currently exists on a redevelopment site;
� R�tention of the runoff from up to a 5 mm storm event on site for infiltration
or re-use (i.e, no minor or major system flow from a si�e for up fo a 5 mm
storm);
m Enhanced vdater quality protection (80% TSS Removal), with consbderation
given to the water quality benefi#s associated with on-site runoff retention;
■ Incentive programs to encourage development to achieve voluntary an-site
runoff retention targefis of 10 mm ia 15 rnm;
i Irnplementation of Low.lmpact Q�evelopment pracfiices vvithin public right-of-
vvays and infiegration of ir�not�ative stormwafier managernent pracfices with
�SUblic open space, where feasibl� and appropa-iate; and,
� Site specifie requirements to preserve the existing storage volume and
protect new development frorr� f600ding in the existing flood storage area af
the south parking lot of the Pickering Town Cenfire.
TMIG � THE MUNICIPAL INFRASTRUCTURE GROUP LTD PAGE i
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Pickering City Centre
STORMWATER MANAGEMENT STRATEGY
CITY OF PICKERING
FINAL • APRIL 2015
Contents
� 1 Introduciion ............................................................................................5
i
� 1.1 Objective ......................................................................................5
1.2 StudyArea ........................:...:....................,.................................6
j1.3 Background and Planning Framework ..........................................7
2 Existing Conditions .............................................................................10
', 2.1 Study Area Characterization ......................................................10
;� ,
2.2 Existing Storm Sewers ...............................................................10
j2.3 Drainage and Hydrology ............................................................13
', 2.4 Pickering Town Centre ...............................................................14
3 Stormwater Management Criteria ........................................................18
�
J3.1 Quantity .....:...........................................................................:...18
3.2 Quality .......................................................................................18
� 3.3 Erosion ......................................................................................19
� 3.4 Water Balance ...........................................................................19
3.5 Criteria Summary .......................................................................19
�
! 4 Stormwater Management Approaches ...............................................20
�
4.1 Conyentional Stormwater Management Practices ......................21
� 4.2 Low Impact Development Pracfices ........:..................................23
' S Develo ment of the Cit Centre SWM Strate
p Y 9Y .................................26
;' 5.1 Alternative Solutions ..................................................................26
' ` 5.2 Evaluation of Alternative Solutions .............................................27
5.3 City Street Strategies .................................................................33
+ 5.4 Stormwater Management in Public Spaces ................................34
I �
5.5 Special Considerations for the Pickering Town Centre ...............35
; 6 Recommended Stormwater Management Strategy ...........................38
i.
; � 6.1 ' Stormwater Management Criteria ...............................................38
6.2 Site Specific Criteria for the Pickering Town Centre Lands.........38
' 6.3 Aspirational Targets ...................................................................40
6.4 Public Realm ..............................................................................41
� i Summary ....................:.........................................................................42
i'
- 8 References ...........................................................:...............................43
i
!.
)
. ppendices
; Appendix A: SWMM5 Model Input and Output
! Rppendix B: Pickering Town Centre Flood Storage Assessment
TMIG � THE MUNICIPAL INFRASTRUCTURE GROUP LTD PAGE iii
i 24
Pickering City Centre
STORMWATER MANAGEMENT STRATEGY
CITY OF PICKERING
FINAL • APRIL 2015
•
Figure 1-1: Pickering City Centre Vision ............................................. 5
Figure 1-2: Pickering City Centre Study Area ..................................... 6
Figure 1-3: Durham Region Official Plan ..................................:.......... 7
Figure 1-4: Cify of Pickering Official Plan ........................................... 8
Figure 1-5: Civic District Rendering .................................................... 8
Figure 1-6: Krosno Creek Flood Reduction Project Area ................... 9
Figure 2-1: Existing Storm Sewer Network ....................................... 11
Figure 2-2: Krosno Creek SWMMS Model Layout ............................. 15
Figure 2-3: Pickering Town Centre Sueface Storage ........................ 16
Figure 4-1: Typical Impacts of Urbanization on the
Hydrologic Cycle ............................................................. 20
Figure 4-2: Example LID Approach within the ROW ......................... 25
Figure 5-1: Sherbourne Common Water Features ............................ 35
Figure 5-2: Pickering Town Centre Vision ........................................ 35
. • I'
Table 2-1: SWMM5 Model Output - Existing Conditions .................. 13
Table 2-2: Pickering Town Centre Surface Storage Volume............ 14
Tabie 3-1: Stormwater Management Criteria 5ummary .................... 19
Tabie 5-1: Change in Peak Flow - Alternative 1 ................................ 28
Table 5-2: Change in Runoff Volume - Alternative 1 ........................ 28
Table 5-3: Change in Peak Flow - Alternative 2 ................................'29
Table 5-4: Change in Runoff Volume - Alternative 2 ..:..................... 29
Table 5-5: Change in Peak Flow - Alternative 3 ................................ 30
Table 5-6: Change in Runoff Volume - AlYernative 3 ........................ 31
Table 5-7: Change in Peak Flow - Alternative 4 ................................ 31
Table 5-8: Change in Runoff Volume - Alternative 4 ......................... 32
Table 5-9: Alternative Evaluation Summary ...................................... 32
Table 5-10: Change in Peak Flow- LID on City Streets ................... 34
Table 5-11: Change in Runoff Volume - LID on City Streets........:... 34
Table 5-12: Pickering Town Centre SYorage Implications ................ 36
PAGE iv TMIG � THE MUNICIPAL INFRASTRUCTURE GROUP LTD
25
Pickering City Centre
STORMWATER MANAGEMENT STRATEGY
CITY OF PICKERING
FINAL • APRIL 2015
7 Introduction
1.1 Objective
The Pickering City Centre area has been identified as an area for growth via
intensification, as recognized by its de5ignation as an Urban Growth Centre in the
Grawth Plan for the Greater Golden Horseshoe, and as an Anchor Hub in Metrolinx's
Big Move. The Downtown Pickering Visiort and Redeve%pment Framework (June
2013) has articulated the desired form of Figure 1-1: Pickering City Centre Usion
redevelopment, as illustrated in Figure
1-1.
The City is also evaluating and planning
for the infrastructure needed to support
this vision for growth, which includes
provision for an appropriate stormwater
management straiegy and related criteria
to mitigate the impacts of intensification
on the receiving watersystems.
To this end, The Municipal Infrastructure
Group Ltd. (TMIG} was retained . by the
City of Pickering to establish a Stormwater Management Strategy corresponding to
the vision far the Pickering City Centre area. In essence the City Centre vision entails
redevelopment and new development within the study area, occurring over time to
replace many or all of the existing older developments. The� majority of the existing
development in the City Centre area pre-dates the adoption of modern stormwater
quantity and quality controls. �
; Current stormwater management strategies typically endeavour to mitigate the
� impacts of new development, premised on the notion that development will introduce
hard surfaces, increase runoff, and degrade water quality. However, where
� redevelopment is proposed in existing developed areas, intensification does not
necessarily yield significarit increases in the e�ent of hard surface or corresponding
� increases in surFace runoff.
As a result, and from a stormwater management perspective, intensification can
represent an opportunity to modernize and update existing infrastructure to more
than offset potential environmental impacts and strive for current quantity, quality, •
erosion, and water balance criteria.
1A(ithin this conte�ct, the objective of the stormwater management strategy for
Pickering City Centre is to target enhancement rather than maintenance of existing
conditions. In addition, intensifica#ion provides an opportunity to introduce ar modify
infrastructure to better complement and integrate with the urban form desired for the
community.
The evaluation of the stormwater management strategy for Pickering City Centre is
being undertaken in parallel with the Krosno Creek Flood Reduction Project
(Section 1.3.4), which establishes the most effecfive means of protecting people and
property from existing flooding problems in the Krosno Creek watershed. The
TMIG � THE MUNICIPAL INFRASTRUCTURE GROUP LTD PAGE 5
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Pickering CifyGentre
STORMWATER MANAGEMENTSTRATEGY
CITY OF PICKERING
FINAL • APRIL 2015
__
models, analyses, and recommendations of the Krosno Creek Fiood Reductian
Project have beeri applied and considered in the development of the stormwater
management strategy for Pickering Gity Centre.
. �
The Pickering City Gentre study area boundarie5 are generally consistent with the
Urban Growth Centre designatian in the Growth Plan for the Greater Golden
Horseshae, with minor changes to include additional contingent properties
recognized as appropriate for growth. These boundaries capture, at the core, the
civic centre, regional shopping centre and existing urban neighbourhoods while
embracing the Kingston Road, Liverpool and Bayly corridors, along with the GO
Transit station to optimize the transit integration to the City Centre (Figure 1-2).
Figure 1-2: Pickering City Centre Study Area
The specific boundaries of the Pickering City Centre study area are the Pine Creek
corridor ta the west, Diana Princess of Wales Park to the East, Bayly Street to the
South, and north parcels facing Kingston Road to the north, representing a total area
of 134 hectares.
The majority af the study area falls within the Krosno Creek watershed, with a small
area west of Liverpool Road draining westward to Pine Creek. Both Krosno and Pine
Creeks ultimately drain to Frenchrnan's Bay and are within the jurisdicfion of the
Toronto and Region Conservation Authority (TRCA).
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j Pickering CityCentre
STORMWATER MANAGEMENT STRATEGY
CITY OF PICKERING
1 FINAL • APRIL 2015
� 1.3 Background and Planning Framework
The study area lies entirely within the City of Pickering, which forms part of fhe
Region of Durham.
�.3.9 Durham Region Officia/ Plan
The Durham Region Official Plan (Adopted 1993, consolidated August 2013)
provides broad land use designations and policies. It shows the study area as
`Urban', including both Living Areas and Employments Areas. It also designates the
Pickering Town Centre and surrounding lands as a Regional Centre.
The Durham Region Official Plan has been significantly updated through Regional
Official Plan Amendment 128 (ROPA 128�. RUPA 128 is in full force and effect, save
and except as it applies to specific policies that remain under appeal. None of the
specific policies under appeal to the Ontario Municipal Board are relevant to current
and planned development in the. Krosno Creek watershed. The Living Area and
Ernployment Area designations through the study area shown in ROPA 128 are
generally unchanged from the previous consolidation, but the Pickering Town Centre
and surrounding areas are now also identified as an Urban Growth Centre. Figure
'I-3 illustrates the location of the Pickering City Centre study area within the context
of the Durham Region Official Plan.
Figure 1-3: Durham Region Official Plan
STUDY
AREA � � � �,x��. � �W � -
� __�._..�._
� -�.� ._._.___.._�. __�
Excerpt of Schedule A, Regional Structure
TMIG � THE MUNICIPAL fNFRASTRUCTURE GROUP LTD PAGE 7
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Pickering CityCenire
STORMWATER MANAGEMENT STRATEGY
CITY OF PICKERING
FINAL • APRIL 2015
9.3.2 City of Pickerirrg Officia! Plan
The City of Pickering Official Plan provides more specific land use designations and
policies. The current Official Plan was adopted in 1997, and was last consolidated in
2010.
There are a number of different land use designations throughout the Krosno Creek
watershed. Lands north of Kingstan Road are generally designated Low and Medium
Density Residential. The area between Highway 401 and Kingston Road, including
the Pickering Town Centre and
Clty Hall, I5 designated Figure 1-4 City of Pickering Official Plan
�. i � :��,���n � � � , �'�
Downtawn Core, and the area �x �
between Highway 401 and Bayly ' I,4
' � ��
Street is designated Mixed Use �� ��' `"�� � � �� �� � "� '
� �:,
Corridor. South of Bayly Street, .x� o� �,� } ' STUDY
� � I � � �. AREA
lands are generall�y designated � � ,� �"`� i,�� ..� � ,
Low Density Residential (west of �_� `� �� {���' r=�
Sandy Beach Road) and I� 3 `
�
Employment (east of Sandy ��� ,'
Beach Road). The major utility ��� ��, ,
and infrastructure uses in the �'���� �'��
!
study area include Highway 401 � �*�` � �� � � �
and the CN Rail corridor. Figure � �-=
�I-4 illustrates #he Pickering Gity � ���= �
���
Centre study area lacation within A � �:_�
th2 GOt1t8Xt Of th2 Piekering Excerpt of Schedule 1, Land Use Structure
Official Plan Land Use Structure.
'.3.3 Pickering Ciiy Centre Intensification Projecf
As previausly noted, the Pickering City Gentre area has been identified as an area for
growth via intensification, as recognized by its designation as an Urban Growth
Centre in the Growth Plan far the Greater Golden Norseshoe, and as an Anchor Hub
in Metrolinx's Big Move. The Dawntown
Pickering Vision and Redevelopment Figure 1-5: Civic District Rendering
Framework (June 2013) has articulated
the desired form of redevelopment, and
provides a comprehensive vision that
will guide growth, inform investment,
and that clearly illustrates a long-term
vision of the City Centre as �a distinct
and vital centre of Pickering.
The study and subsequent planning
processes have resulted in
recommendations for amended Official
Plan policies (OPA 26) and urban
design guidelines, and will also
recommend zoning strategies ta
sffectively plan for the intended growth
in the Gity Centre area.
PAGE 8
TMIG � THE MUNICIPAL INFRASTRUCTURE GROUP LTD
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Pickering CityCentre
STORMWATER MANAGEMENT STRATEGY
CITY OF PICKERING
FINAL • APRIL 2015
The starmwater management strategy far the City Centre area utilizes the vision to
evaluate anticipated impacts and the effectiveness of mitigation mechanisms that
should accompany development.
1,3.4 Krosno Creek Flood Reduction Project
As noted in Sectian 1.2, the Pickering City Centre area faiis almost entirely within the
Krosno Creek watershed. Known flooding and erosion concems along reaches of
Krosno Creek have led to the completion of several flood risk and mitigation studies
over the years.
The Krosno Creek Flood Reduction Project was
initiated by the City of Pickering, in parallel with
the Pickering City Centre Stormwater
Management Strategy, to establish and
implement the most effective means of
protecting people and property from existing
flooding problems in the Krosno Creek
watershed.
The models, analyses, and recommendations of
the Krosno Creek Flood Reduction Project have
been applied and considered in the development
of the stormwater management strategy for
Pickering City Gentre. In particular, the Krosno
Creek Flood Reduction Project generated a
calibrated and verified SWMMS
hydrologic/hydraulic model of the Krosno Creek
watershed to predict the peak flow rates and
water levels along the drainage systems for a
range of standard design storm events.
Figure 1-6: Krosno Creek Flood
Reduction ProjectArea
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� This model was applied fo simulate the effectiveness of various practices to define
j the stormwater manag.ement strategy for Pickering City Centre, and simultaneously
explore the impacts of intensification within Pickering City Centre to the broader
, watershed.
TMIG � THE MUNICIPAL INFRASTRUCTUREGROUP LTD
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PAGE 9
Pfckering City Centre
STORMWATER MANAGEMENT STRATEGY
CITY OF PICKERING
FINAL • APRIL 2015
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Physiography and Topography: The Pickering City Centre study area lies within
the Iroquois Plain physiographic region, as defined in the Physiography of Southern
Ontario (Chapman and Putnam, 1984). This is the area below the former Lake
Iroquois shoreline which was smoothed by wave action and glacial deposits. The
witlth of the Iroquois Plain (as measured fram the current Lake Ontario shoreline)
widens rapidly west of Scarborough, with sandy soil deposits near the north end of
the plain, and a mix of till deposits, drumlins and sandy lacustrine deposits across the
remainder of the width to Lake Ontario.
Soifs and Groundwater: Information on soils throughout the Pickering City Centre
study area was obtained from the Soil Survey of Ontario County (Olding et. al.,
1956), and the findings agree with the overail physiography of. the Iroquois Plain.
From Bayly Street north to Finch Avenue, which encompasses the Pickering City
Centre area, the soil is predominantly Smithfield Clay Loam, transitioning to Brighton
Sandy Loam north of Finch Avenue and Schomberg Clay Loam south of Bayfy
Street. Smithfieid Clay Loam is considered Type C under the US Soil Conservation
Service (SCS) ciassification, with limited infiltration capacity.
Land Use: Pickering City Centre today hosts a range of land uses, building forms
and several important public spaces, spanning the 134-hectare area. Just south of
Highway 401, Krosno Creek emerges as an open channel in the area norfh of Bayly
Street and therefore creates a small, natural area within the City Centre core. With
respect to population, the City Centre area is present(y home to about 5,000
residents and 5,000 jobs. The current land use breakdown (as presented in the
Downtown Pickering report, Urban Strategies, June 2013) includes:
■ 3% office
■ 6°/o civic and recreation space
■ 16% residential
■ 42% retaii, commercial,,and light industrial
� 12% stand-alone surface parking or undeveloped
• 20% road surface and right-of-way _
. ;. . .
The existing storm sewer system is shown in Figure 2-1. Major trunk sewers run
along Glenanna Road, Valley Farm Road; Pickering Parkway and Bayly Street. The
Pickering Town Centre is serviced by the storm sewer running just west of Glenanna
Road. This system also receives flows from the upstream residential
neighbourhoods. All of the storm sewer systems north of Highway 401 converge at a
single storm outfall to the north of the Highway 401 ditch just west of Glenanna Road.
PAGE 10 TMIG � THE MUNICIPAL INFRASTRUCTURE GROUP LTD
31
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L�CEND:
PlCf��RIM1iG C6iY CENI"�E
8Q1JNdARY
EXI5TI14�G DUR'HAM R�G��IV
STORM 5E'WER
EKISTl6VG CITY �F PICKERI�fG
STORNlSEWER
" SCALE: 7'7.644 ..__.._. .._.
� TIIIIIG �''� 2p PICKEiF�i�JG C[TY CE�JTRE SVIIM STR��E+GY OATE: JULY2014 �G�SO
� uKncs P1GliRE No.
� d °�"'°"� EXlSTING STO�R�II SEVWER NETIN�RK dESIGMEC7 BY: ET �RAWN 6Y:CAp
n.,ti�w.��vma��r,.,..,.,�..r.,,���w .�as.nxexs
CHECKEQ 6Y: SH CNECKEf3 BY:
--;
PicEcering City Cent�e
STORMWATER MANAGEMENT STRATEGY
CITY OF PICKERING
FINAL- APRIL 2015
A 4.3 m wide x 2.4 m.high concrete box culvert carries ,the flow under Highway 401,
and then transitions to a pair af CSP cu(verts (1500 mm and 2100 mm diameters)
that continue through the CNR co�ridor. A large storm sewer on Bayly Street
conveys runoff from most of the areas between Bayly Street an.d Highway 401 to
Krosno Creek.
f . • • . s s a • ,
A new SWMM5 hydrologic/hydraulic model of fhe Krosno Creek waters�ed was
created, calibrated and verified to support the Krosno Creek Flood Reduction Project,
which is being undertaken in parallel with this study. The model was developed to
establish existing flows, water levels and potential flood damages through the Krosno
Creek watershed, and to evaluate alternatives to reduce flood damages. More
information on the development, calibration and simulation of the SWMM5 model can
be found in the Project File Report (PFR) for the Krosno Creek Flood Reduction
Projec� (TMIG, 2014). . - �
The calibrated SWIVlM5 modsl of the Krosno Creek watershed was then used to
simulate the 2 year through 100 year return period storm events. T�e 1 hour AES
distributions from the City of Pickering Stormwater Managemerit Guidelines were
adopted for the 2 year through 1,04 year storms. ihe existing peak ffow rates at key
locatians along Krosno Creek are presented in 'fal�fe 2-�. The model sub-
catchments and flow node tocations are presented in Figure 2-2. �
Table 2-1: SWMM5 Model Output— Existing Conditions
TN{IG � THE MUNICIPAL INFRASTRUCTURE GP.OUP LTD
PAGE 13 �
33
Pickering; City Cen:tre
STORMWATER MANAGEMENT STRATEGY
CiTY OF PICKERING
FINAL • APRIL 2015
PAGE 14
34
Note thaf there is a significar�t increase in flow rates at Bayly Street, where drainage
from a large area to the east enters Krosno Creek. Below Bayly Street, �lows are
relatively constant until the open channel systems from the east enter Krosno Creek
where it flows east of Sandy Beach Road�
2.4 Pickerir�g To�nrn. Gen#r�
As noted in Sectiort 2.2, the entire
Krosno Creek watershed norEh of
Highway 401 drains to the si�gle
concrete box culvert under Highway
401, which is directly connected to a
pair of CSP culverts (1500 rnm and
2100 mm diameters) under the CNR
tracks. These culverts significantly
restrict the flow in the Krosno Cresk
system and contribute to high flood
levels upstream of Highway 401.
With tl�e potentialiy elevated flood levels upsfream of the CNR rail embar�kmeni and
associated extent of flooding, a significant vo,lume of water would be stored on the
surface of the south Pickering Town Centre parking lot, and this volume could
aftenuate fiows in the system. The potential storage valume in the parking lot at �
difFerent elevations was calculated trom the DEM; and the resulting volume was
represented in the SWMMS model {up to 24,500 m3 at 85.0 m). The area of ponding
at different elevations up to and inchuding 85:0 m is shown in Figu�e 2m3, and the
corresponding storage volumes are summarized in Tafa[e 2-2.
Table 2-2: Pickering Town Centre SurFace Starage Volume
, r : -s �:. � � � �✓ : � ,... r t �.
i
Eleuat�on Rr�a (m�) Uaiur�� (rsr'�, Nrn�"es � �
x. � y�� � _� . � � ���-��
83.0 135 - Flooding contained in Hwy 401 ditch
84.0 1,280 710 Flooding contained in Hwy4D1 ditch
84.5 23,825 6,990 Flooding on Pickering Town Centre south parking lot
84.73 34,195 13,670 Pickering Town Centre first floor efevation
85.0 46,370 24,540 . Highway 401 overtopped .
TM1G J THE MUNICIPAL INFRASTRUCTURE GROUP LTD
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Pickering City Centre
STORMWATER MANAGEMENT STRATEGY
CITY OF PICKERING
FINAL • APRII 2015
The City of Pickering was undertaking a City-wide master plan for stormwater
management during the design and construction of an expansion to the Pickering
Town Centre in the eariy 1980's. The Stormwater Management Study (Simcoe
Engineering, 1984) specifically identified the need for 20,000 m3 of flood storage in
the area upstream of the Highway 401 culvert. This was deemed necessary in order
to limit peak flows to the capacity of the CNR culverts and the downstream concrete-
lined channel.
However, consfruction had commenced on the Pickering Town Centre expansion and
south parking area before the Stormwater Management Study was completed. The
1984 report states that the City worked with the developers of the Pickering Town
Centre to re-design the south parking lot to create approximately 12,350 m3 of fiood
storage which, although less than the previously esfablished requirement, was
determined to be sufficient for the purposes of managing flood risk and maintaining
the downstream drainage regime. This generaily agrees with the storage
calculations summarized in Table 2-2, which estimate that approximately 13,700 m3
of flood storage is availabfe up to the first floor elevation of the Pickering Town
Centre (84.73 m).
The SWMM5 model indicates that the combination of the storage and culvert
restrictions reduce the 100 year storm peak flow rate by approximately 35% in the
most ffood prone reaches of Krosno Creek downstream of Highway 401. The
SWMM5 model also predicts that approximately 8,800 m3 of water would be
temporarily stored on the south parking lot at the Pickering Town Centre during a 10d
year storm, corresponding to a maximum ponding elevation of 84.66 m. . This is
only 7 cm below .the level of the first floor at the Pickering Town Centre (84.73 m).
The internal storm sewers connecting the Pickering Town Centre to the municipal
system on Pickering Parkway were not represented in the SWMM5 model of the
Krosno Creek watershed. It is possible that, with energy losses along these internal
storm sewers, flood levels could approach or exceed the first floor elevation of the
Pickering Town Centre during a 100 year storm. �
The Pickering Town Centre was reportedly flooded during the severe storm of August
2005. While the August 2005 storm generated more rainfall than a 100 year storm,
there contrnues to be a risk of flooding at the Pickering Town Centre.
More information on the significance of the storage on the south parking lot at the
Pickering Town Centre is included in Sectian 5.5.
TMIG � THE MUNICIPAL INFRASTRUCTURE GROUP LTD
PAGE17
37
Pickering City Centre
STORMWATER MANAGEMENTSTRATEGY
CITY OF PICKERING
FINAL' • APRIL 2015
3 Stormwater Management Criteria
PAGE 18
�i :�
Relevant stormwater management design criteria for the study area have been
compifed as part of this study and are in accordance with City of Pickering Design
Criteria, Toronto and Region Conservation Authority (TRCA) standards, and the .
Ontario Ministry of Environment (MOE) Stormwater Management Planning and
Design Manual (March 2003).
3.1 Quantity
Water quantity control describes measures intended to offset the increases in peak
flow that result from the introduction of impervious surfaces, in an effort to mitigate
the potential for increased fiood risk to downstream areas.
Where quantity control criteria have been established through a watershed or sub-
watershed study, these are to form the basis for defining, targets. For areas where
quantity control criteria have not been established through such studies, the City of
Pickering requirement is to provide posf-development to pre-development peak flow
controi for the 2 year through 100 year storm events.
Specific water quantity control targets have not been defined for the Krosno Creek
watershed. Therefore, the requirement is to provide post-development to pre-
development peak filow control for the 2-year through 100-year storm events. This
also fulfills tfie r,equirements set by the TRCA.
Additionally, it must be noted that the City's �preference is to control the post-
developrnent to pre-development peak fiows based.on a maximum runoff coefficient
of 0.5 for pre-development conditions. This criterion has been applied to more recent
redevelopment sites in the City of Pickering and has been considered during the
evaluation of the alternative solutions. �
3.2 Quality
Water quality control describes measures intended to protect receiving water bodies
from the water quality degradation that may result from development. The water
quality requirement for all watercourses and water bodies within TRCA's jurisdiction
is to provide an Enhanced level of protection (80% TSS Removal), in accordance
with the Ministry of EnvironmenYs Stormwater Management Planning and Design
Manual (2003). Section 4.3 of the City of Pickering Stormwater Management
Guidelines stipulates the same requirement for all development within the City. The
City's Guideline also notes that "Reducing the volume of runoff has inherent water
qualify .benefits as reducing the volume of runotf from a site will also reduce the
loading of pollutants fo watercourses."
The 5 mm vofume control target associated Wftll erosion and water balance,
described in the following sections, can therefore also be deemed to provide some
degree of water quality treatment. .
TMIG � THE MUNICIPAL INFRASTRUCTURE GROUP LTD
Pickering City Centre
STORMWATER MANAGEMENT STRATEGY
CITY OF PICKERING
FINAL • APRIL 2015
• •' ''
Erosion -control describes measures intended to mitigate increases in erosion
potential to receiving watercourses resulting from development. The TRCA sets the
minimum erosion criteria as the on-site retention of the first 5 mm of precipitation.
If a site drains to a sensitive creek or if a comprehensive study is needed, then a
geomorphic study is required fo determine the erosion threshold and mitigation
strategies. If a site includes a SWM pond then retaining runoff from a 25 mm storm
for 48 hours may be required. �
The City of Pickering provides additional guidance with respect to erosion control. For
small infill sites and site plans less than 5 ha the minimum erosion control
requirements are:
■ Extended detention of the 4 hour, 25mm Chicago distribution storm for 24 hours,
or;
■ Maximize runoff reduction from,the site through infiltration, evapotranspiration
and stormwater reuse; and,
■ For greenfield developments, a detailed erosion control .analysis shall be
completed based on geomorphic assessment of critical erosion flow thresholds.
Re-development within Pickering City Centre would not be considered greenfield
development, and therefore the first and/or second criteria are applicable.
� . 3.4 Water Balance
Water balance describes the stormwater management approach that endeavours to
replicate the hydrologic conditions that existed prior to development. The water
Ibalance criterion established by TRCA is generally to maintain existing groundwater
recharge to the extent feasible, witfi a typical minimum criterion of 5 mm on-site
retention (i.e. no runoff from the site for up to a 5 mm storm).
3.5 Griteria Sumrnary
Table 3-1 summarizes the stormwater management criteria that are applicable to
redevelopment and intensification within the Pickering City Centre area.
Table 3-1: Stormwater Management Criteria Summary
TMIG � THE MUNICIPAL INFRASTRUCTURE GROUP LTD
PAGE 19
39
Pickering CityCentre
STORMWATER MANAGEMENT STRATEGY
CITY OF PICKERING
FINAL � APRIL 2D15
I
• " . ` . . • ' ' � • • i . '
PAGE 20
40
Stormwater management measures are intended to achieve one or a combination of
several objectives, principally to address the. impacts of urbanization. Specifically,
during storm events, the increase in surface runoff Figure 4-1: Typical Impacts ofi
usually generated by urban communities can result Urbanization on the Hydrologic Cycle
in flooding and erosive damage to our streams and
structures. In addition, urbanizatia.n can contribute ���.�,}�aR����� _ .
to degraded water quality in creeks, rivers and `�,
lakes. � .. � ��
Stormwaier management is needed to manage the
quantity and quality of runoff generated by urban
communities in order to prevent these impacts.
Stormwater is conventionally managed in three
stages: at the source, in the conveyance system,
and/or at the "end-of-pipe". The source, or lot level,
is tlie landscape surFace where the rain falls (roofs,
lawns, parking lots, driveways). The conveyance
system is the network of storm sewers and
overland flow paths (roadways and ditches) that
take the runoff from the source to the end-of-pipe.
The end-of-pipe systems include stormwater
pands, wetlands, Qr infiltration basins. With respect
to quantity control, conventional approaches are
principally designed for peak flow management,
which is the storage and slow release of runoff
over time to achieve a desired peak flow target.
These measures da not generally mitigate the
increase in the volume of runoff that results from
urbanization.
•:n ,��,,
�a���:�:�o-d �fp . �
cred'�t US EPA
Low impact development (LID) is the next evolution in stormwater management fhat
in some cases reintroduces older technologies, and provides an alternative set of
mechanisms to manage stormwater volume, in a manner that can better integrate
within the urban , fabric, pravide relief to hard downstream infrastructure such as
sawers, ponds and channels, and distribute the managament of runoff to improve our
ability to adapt to climate change. In general the objectives of low impact
de�elopment are to:
Brief descri�tions of both conventional and low impact development practices are
provided in the following subsecfions. Detailed descriptions and design guidance
TMIG � THE MUNICIPAL INFRASTRUCTURE GROUP LTD
Pickering City Centre
STORMWATER MANAGEMENT STRATEGY
CITY OF PICKERING
FINAL � APRIL 2015
pertaining to these practices can be found in the Ministry of Environment's
Stormwater Management Planning and Design Manual (2003), the TRCA Stormwater
Management Criteria document (August 2012), the Low Impact Development
Stormwater Management Planning and Design Guide (TRCA/CVC, 2010), and the
City of Pickering Stormwater Management Design Guidelines.
, . . . . . . _ . ..- . - .
4.9.9 Lot Level Controls
Lot level controls provide stormwater management at the individual lot or site level,
and can include conventional approaches such as rooftop and parking lot quantity
control, and oil-grit separators for water quality. `
Rooftop Storage: Rooftop storage is a method of restricting the discharge rate from
roof drains to provide rooftop detention of stormwater. Flat building roofs can be used
to store runoff to reduce peak flow rates to storm sewer systems. Rooftop storage is
economicai, often requires little extra cost during construction, and is generally most
appiicable to large flat commercial and industrial rooftops; residential roofs are
usually peaked with few opportunities for storage. Rooftop storage is widely applied
for infill development scenarios to mitigate the need for downstream storm sewer size
increases. Note, however, that current City of Pickering guidelines generally do not
allow rooftop storage for water quantity control.
i Parking Lot Storage: Parking lot storage is the practice of introducing depressed
_ areas within a parking lot, in combination with catchbasin restrictors or orifices in the
� storm sewer, to detain stormwater and reduce peak flow rates in receiving sewer
systems. Parking (ot storage is economical with sfightly increased costs for
i construction, most suited to eommerciai and industrial lots, and less suited to
residential areas due to the small parking areas. It has been widely applied for infill
developmen�s to mitigate the need for downstream storm sewer size increases.
Dil-Grit Separators: An oil-grit separator is a device that provides water quality
treatment of runoff. it is a structure that is installed underground, within the storm
sewer system. A unit typically consists of one or more water-fiiled chambers that
remove sediment, screen debris, and separate oil from stormwater. The water-filled
chamber(s) has the effect of slowing the velocity of stormwater runoff, allowing some
of the particulate matter to settle and allowing suspended oil to rise. There are a
number of different oil-grit separator types and manufacturers, with varying
performance and application specifications. Oil-grit separators only provide water
quality treatment; there is little to no storage available in the devices to reduce the
peak flow rate through the system.
�.9.2 Conveyance Controls
Conveyance controls refer to controls placed en route from the source where runoff is
generafetl to the outlet or receiving water body, and these function by providing
attenuation, retention, and/or active water quality treatment while runoff is in transit
from source to outlet. Some forms of conveyance controls include aversized storm
sewers, oii-grit separators, infiitration galleries, or bioswal.es, and the majority of
these measures can be categorized as either active controls or low impact
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CITY OF PICKERING
FINAL • APR1L 2015
development measures. These measures can be particularly effective for road
drainage, which is normally directed without control to either end-of-pipe facilities or
receiving water bodies. The feasibility of implementing conveyance controls is usually
dependent on the ability to accommodate these features within the municipal right-of-
way. The following are examples of conventional conveyance controls.
Underground Storage: Underground storage is a method of providing storage
through the use of oversized sewer pipe and implementing orifices in the sewer to
detain the stormwater in the underground storage facility.
Rear Yard Storage: Rear yard storage is a method of implementing catchbasin
restrictors in rear yard catchbasins to create stormwater storage within the yard; for a
neighbourhood these function together as a conveyance measure to attenuate peak
flows.
4.1.3 End-of-Pipe Controls
End-of-pipe controis are facifities that receive stormwater runoff from a conveyance
system and provide treatment prior to discharge to a receiving water body. Within the
context of the treatment train approach, an end-of-pipe facility is designed as the last
stage of runoff treatment. It is common for a new `greenfield' development to
incorporate a stormwater management pond or similar facility as a method of end-of-
pipe controL
In general the implementation of an end-of-pipe solution is dependent on the amount
of space availabie to build a facility that is able to service the applicable site.
Pickering City Centre is a fully urbanized and developed corridor and therefore has
limited space to build a facility that is large enough to service the area. Opportunities
to implement an end-of-pipe facility that services the broader Krosno Creek
watershed, including the City Centre area, were explored as part of the Krosno Creek
Flood Reduction Project.
W�tland: The constructed wetland is one of the preferred end-of-pipe SWM facilities
for water quality enhancement. These have shallow depths for both the permanent
pool and the active storage zone, are suitable for providing the storage needed for
erosion and flood control purposes. These types of facilities are typically used for
drainage areas greater than 5 ha.
Ut►et Pond: Wet ponds are also preferred end-of-pipe SWM facilities for water quality
enhancement. They are constructed basins that maintain a permanent pool of water
throughout the year. These ponds treat the stormwater by allowing the particles to
settle and algae to take up the nutrients, and are typically more e.ffective than
wetiands for water quantity control. These fypes of faci(ities are typically used for
drainage areas greater than 5 ha.
Infiltration Facility: Infiltration facilities involve tha capture and infiltration of
stormwater runoff from impervious surfaces to reduce water pollution, and stabilize
stream flows. A method of infiltration is a rock-filled trench with no outlet that receives
stormwater runoff. The stormwater runoff passes through some combination of pre-
treatment measures, such as a swale or sediment basin, before entering the trench.
The runoff is stored in the voids of the media and will slowly infiltrate through the
bottom and into the soil matrix over time.
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Pickering City Centre
STORMWATER MANAGEMENT STRATEGY
CITY OF PICKERING
FINA� � APRIL 2015
An infiitration facility can also take the form of a p(anted depression area that
captures stormwater runoff from either landscaped or impervious surfaces, and
similarly allows runoff to be stored and infiltrated through the base of the facility.
These are referred to as bio-retention cells, and typicaliy have engineered and
constructed subgrades to account for altered and compacted soil conditions. The
subgrade ensures adequate percolation of captured runoff by using a perForated
drain pipe in a rock bed covered by a sandy soil mixture. Infiltration facilities are
typically suited to drainage areas less than 5 ha.
� • .. �- '•. ''
Low impact development practices (LID's) refer to those measures that are intended
to provide volume management, and in other words manage the rain where it lands
via methods that encourage infiitration, reuse, and evapotranspiration. As previously
noted the Low Impact Development Stormwater Management Planning and Design
Guide (2010) provides detailed information on the suitability, selection, design,
installation, and anticipated effectiveness of the fuil range of LID practices.
r In general LID practices promote decentrali�ation of stormwater management
_, infrastructure, and add resiliency in the face of potentially changing climate
conditions. Beyond achieving stormwater management objectives, low impact
� development approaches also represent an opportunity to satisfy the broader notions
of sustainability and quality of life that are cansistent with the vision for Pickering City
Centre. Furthermore, LID practices can often be integrated as amenities into the
� urban fabric. The following subsections briefly describe a few of the many LID
_� approaches that could be considered as part of urban redevelopment within the study
area that are appropriate for high density areas. Review of the Low Impact
,
� Development Stormwater Management Planning and Design Guide (2010) is
recommended to comprehensively explore options and suitability as part of specific
� . development applications.
4.2.7 Low Impact Development Approaches
Green Roofs: Green roofs are an extension of
`�,� , 7 � I �:a .,w= -.
traditional rooftop storage techniques. A green roof is a j i
roof with a layer of drainage and growing media that �
supports living vegetation. Green roofs can achieve °`�
reduced peak flows and runoff volume, improved air .. ��
��.
quality, lower energy use and can moderate summer air �` ��
temperatures. A rooftop garden can provide a 45%
reduction in runoff via evapotranspiration. Applicability within Pickering City Centre is
dependent on the anticipated form and function of each individual development.
Rainwater Flarvesting: Rainwater harvesting is the
storage and utilization of rooftop runoff for, typically,
landscape irrigation or greywater reuse. In general, the
concept entails the conveyance Df rooftop runoff to a
cistern for storage and eventuai use, with the cistern
size based on typical reuse demands. Rain barrels are a
common approach to rainwater harvesting in low density
residential applications. fn high density applications,
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STORMWATER MANAGEMENT STRATEGY
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FINAL • APRIL 2015
PAGE 24
44
underground tanks are often needed to store a sufficient volume of rooftop runoff.
Rainwater harvesting provides a number of benefits, including the reduction in runoff
volumes and rates from the site, along with a reduction in the usage of municipal
water. While the cost savings in terms of municipal water to the owner are nominal
based on current potable water charges; easing the community-wide strain on _
municipai infrastructure can have a much more substantial and long-term benefit.
Within Pickering City Centre, rainwater harvesting could be considered as part of
redevelopment to supply rainwater for the irrigation of landscaped areas, and/or to
supply water within a building as part of a greywater reuse strategy.
�ermeable Pavement; Permeable pavements are a �`� ��
type of otherwise impervious surFace treatment
equipped with spaces or gaps that allow for the ��
collection of surface runoff, along with a suitably
configured granular substrate, thus providing the
potential for infiltration and groundwater recharge. Unit
pavers are used for low traffic parking lots, streets,
driveways, and walkways. For maximum benefit, permeable pavement requires
suitabie soils and a sufficient depth to water table to allow for infiltration. The area
must also have a relatively flat topography and a low risk of spill or contamination in
order to prevent contamination of the soils and groundwater.
FZain Gardens: A rain garden is a planted depression
area that captures stormwater runoff from either
landscaped or impervious areas and allows for storage
and infiltration. The rain garden can provide water
quality, erosion, and water quantity control through the
recluction in surFace runoff and the increase in
evapotranspiration and infiltration. For maximum benefit,
a rain garden requires suitable soils and a sufficient depth to the water table to
encourage infiltration.
�legeiated Filter Sfirips: Filter strips are vegetated areas � �����' ��`
that are intended to treat sheet flow from adjacent "�� �;���'�"" ���' ��
�
impervious areas. Fiiter strips function by slowing runoff�
velocities and filtering out sediment and other pollutants,
and providing some infiltration into underlying soils.
Sirnilar to rain gardens, the opportunity to incorporate
vegetated filter strips relies on the green space available within the City Centre core.
4.2.2 Low lmpact Development within ROW
The feasibility of incorporating low impact development_ into right-of-ways and open
spaces requires a detailed review of the other demands of these spaces with respect
to utilities, services, transportation modes, and other urban design considerations. An
evaluation of the anticipated benefits of incorporating low impact development
practices into the.public realm has been completed to provide future guidance on,the
feasibility of these approaches, to be reviewed in concert with detailed streetscape
and open space pianning.
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A suitable low impact development
approach wifhin ROWs consists of
infiltration trenches / linear bioretention
trenches, equipped with porous filter
media ta provide runoff attenuation to
address quality and erosion control
requirements. Figure 4-2 iliustrates a
recent example, which was developed
and installed for a section of Elm Drive
West in Mississauga, and included
concrete planter boxes as part of the
design to integrate with the urban
character of the ROW.
This type of configuration was analyzed
within the context of the vision for
Pickering City Centre. A typical
installation would include a granular-
filled trench approximately 1 m wide x
1.2 m deep on one ar both sides of the
road. The trench could �e open and
landscaped, as illustrated in Figure 4-2,
or buried under the pavement or boulevard. With an assumed porosity of 0.40, each
trench could provide 0.48 m3 of storage per metre of road length. For Elm Drive and
ofiher recent installations, the design targeted the capture of the runoff from up to a
25 mm rainfall for infiltration. .
Pickering City Centre
STORMWATER MANAGEMENT STRATEGY
CITY OF PICKERING
FINAt • APRIL 2015
Figure 4-2: Example LID Approach within the ROW
Section 5.3 of the Downtown Pickering Vision for Intensification (Urban Strategies,
June 2013) includes typical sections for a range of streets in Pickering City Centre.
Suggested right of way widths range from 18 m for local streets to 28.5 m for Valley
Farm Road. Hard surfaces (travelled lanes, bike lanes, on-street parking, sidewalks)
typically cover 80 % to 90 % of the right-of-way width.
For an 18 m wide right-of-way at 90% impervious, the runoff from a 25 mm rainfall is
estimated to be 18 m x 0.90 x 25 mm = 0.4 rn3 per metre of roadway. This could be
captured and stored within a 1 m wide trench on one side of the road. For a 28.5 m
right-of-way at 90°lo impervious, the runoff from a 25 mm rainfall is estimated to be
more than 0.6 m3 per metre of roadway. It would be necessary to construct trenches
on both sides of the road or install a wider and/or deeper trench to capture the
resutting runoff for infiltration.
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STORMWATER MANAGEMENT STRATEGY
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FINAL • APRIL 2015
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46
� - - � • ' • ' ' ' � . •
5.1 Alternative Solutions
Alternatives associated with stormwater management speak to the measures that
need to be put in place to manage fhe quantity, quality, erosion, and water balance
impacts of development, often in an effort to maintain existing canditions. However,
within the redevelopment context needed to realize the vision for Pickering City
Centre, the objective of the stormwater management strategy is to target
enhancement rather than maintenance of existing conditions, feasibly and in a
manner that will complement the future community.
The alternatives defined in the following subsections have been developed with the
intention of achieving this objective, yielding strategies that can be impiemented as
part of redevelopment. Broader watershed-scale stormwater management
requirements and strategies have been evaluated as part of tlie Krosno Creek Flood
Reduction Project.
5.1.1 A/ternative 1: Current Formalized Criteria
(On-Site Control with 5 mm Retenfion)
The first aiternative sofution is a combination of the minimum stormwater
management criteria described in Seciion 3. On-site control is assumed to be
impiemenfed in each development sifie or block, in order to provide post-development
to pre-development peak flow control from the 2-year through 100-year storm events.
Moreover, 5 mm of rainfall over the site area wili be captured and utilized on-site
through the implementation of low impact development measures, including but not
limited to permeable pavements, green roofs, bioretention, and rainwater harvesting.
The 5 mm threshoid is documented as criteria within the TRCA Stormwater
Management Criteria Document (August 2012), and has been implemented as part of
the City of Toronto's Wet Weather Flow Management Master Plan (2006). This
retention re.quirement is achievable and practical in relation to modern development
practices.
Quantity control can be provided through underground and/or surface storage on .
each re-development site or block.
5.9.2 Atternative 2: Enhanced Quantity Control
(On-Site Controf with 5 mm Retention anaf 50% Imperviousness)
For the second alternative, on-site control is assumed to be implemented in each
development block, in order to provide post-development to pre-development peak
filow control from the 2-year through 100-year storm events. However, in this case,
the pre-development peak flows must be calculated using a maximum runoff
coefficient of 0.50, regardless of how much impervious surface covers the site prior to
re-development. This is consistent with the City of Toronto's Wet Weather Flow
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Pickering City Centre
STORMWATER MANAGEMENT STRATEGY
CITY OF PICKERING
FINAL • APRIL 2015
Management Master Plan (2006), and this criterion has been requested by City of
Pickering staff on recent re-development appfications. The potentially increased
quantity control can be provided through underground and/or surface storage on
each re-development site or block.
Moreover, 5 mm of rainfall over the site area will be captured and utilized on-site
through the impiementation of low impacf development measures, including but not
limited to permeable pavements, green roofs, bioretention, and rainwater harvesting.
5,1.3 Alternative 3: Enhanced Quantity and Volume Contro/
(On-Site Control wiih 10 mm Retention and 50% Imperviousness)
The third alternative maintains the quantity control criterion from Alternative 2,
whereby post-development peak flows are controlled to pre-development rates, and
pre-development conditions are represented by a maximum runoff coefficient of 0.5.
Moreover, 10 mm of rainfall over the site area will be captured and utilized on-site
through the implementation of low impact development meesures, including but not
limited to permeabie pavements, green roofs, bioretention, and rainwater harvesting.
_. j Mandating enhanced site runoff volume control wili increase the extent of volume
control, wiil assist in reducing peak flows generated by each parcel, and wiil further
supplemenf conventional water quality treatment practices. Retention requirements of
l 10 mm tend to be associated with progressive sustainability mandates, such as
LEED certified projects, and will usually require an extensive form of rainwater reuse
� to achieve the target.
5.1.4 Alte�native 4: Enhanced Quantity and Volume Control
(Orr-Site Control wifh 95 mm Retention and 50% Imperviousness)
The final alternative also maintains the quantity control criterion from Alternative 2,
whereby post-development peak flows are controaled to pre-development rates, and
pre-development conditions are represented by a maximum runoff coefFicient of 0.5.
Moreover, 15 mm of rainfall over the site area will be captured and utilized on-site
through the implementation of low impact .development measures, including but not
limited to permeable pavements, green roofs, bioretention, and rainwater harvesting.
Mandating enhanced site runofF volume control wiil increase the extent of volume
control, wili assist in reducing peak flows generated by each parcel, and may
eliminate the need for water quality treatment practices. Retention requirements of 15
mm tend to be associated with progressiue sustainabitity mandates, such as LEED
certified projects, and will usually require an extensive form of rainwater reuse to
achieve the target.
. . � . .
The effectiveness of each alternative stormwater management strategy was
simulated by modifying the Krosno Creek watershed SWMM5 model described in
Section 2.3. The results of the analyses are summarized in the following
subsections> with additional detail provided in Appendix A.
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Pickering City Centre
STORMWATER MANAGEMENT STRATEGY
CITY OF PICKERING
FtNAL � APRIL 2D15
5,2.1 Aliernafive 9: Current Formalized Criteria
(On-Site Control with 5mm Retention)
The SWMMS model for the Krosno Creek watershed was modified to reflect
Alternative 1, which represents future conditions in combination with current
formalized stormwater management criteria as described in Section 5.1.1. This
alternative was represented in SWMM5 by first calculating the area within each
model sub-catchment that is proposed for re-development in the Vision for Pickering
City Centre (Urban Strategies et. al., June 2013), and re-calculating .the
imperviousness of each model sub-catchment assuming that the redeve�opment will
be 80 % impervious (consistent with the recommended value for high density
residential development in the City's Stormwater Management Guidelines). Similarly,
the required 5 mm on-site runoff retention was represented by increasing the
impervious area initial abstraction depth to 5 mrn for the re-developing fractions of the
City Centre SWMM5 model sub-catchments. Calculations for the revised catchment
% impervious values and initial abstraction depths�are included in Appendix A. Note
that in many sub-catchments, the revised imperviousness is lower than existing
conditions.
The revised SWMM5 model was used to calculate the peak flow rates and water
levels in Krosno Creek and the total runoff volumes from the Pickering City Centre
sub-catchments for the 2 year through 100 year return period storm events. Table
5-1 summarizes the percentage change in peak flow rates from the existing condition
that could be anticipated under Alternative 1, while Table 5-2 summarizes the
corresponding percentage change in runoff voiume from the model sub-catchments
covering the Pickering City Centre area. Detailed model output can be found in
Appendix A, with node locations illustrated on Figure 2-2.
Table 5-1: Change in Peak Flow — Alternative 1
-1.5% -1.0%
-2.5% -1.9%
-1.6% -1.4%
Tabls 5-2: Change in Runoff Volume — Alternative 1
-4.9% I -3.6%
-0.8°fo -0.1 %
-1.5% -1.5%
-2.3% -1.8%
-0.1% -0.1%
-1.3°/a -1.2°/a
-1.8% -2.0%
in peak flow relative to existrng conditions
-3.1 % I -2.7°/a I -2.4% I -2.2%
runoff volume relative to existin.q conditions
The SWMM5 model predicts that the redevelopment of Pickering City Centre,
applying standard formalized criteria, will reduce peak flow rates by up to 2.5 % for
the 2 year storm, _and up to 2.0 % for the 100 .year storm. The greatest reductions in
peak flow rates occur south of Bayly Street, downstream of the outlet from the large
sewershed located between Highway 401 and Bayly Street.
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Pickering City Centre
STORMWATER MANAGEMENT STRATEGY
CITY OF PICKERING
FItJAL • APRIL 2015
The PFR for the Krosno Creek Flood Reduction Project determined that up to 4
buildings are at risk of flooding from Krosno Creek during a 2 year storm. The
number of potentialfy impacted homes rises to 56 for a 10 year storm, and 64 for a
100 year storm. Reductions in peak flow rates from the City Centre area should
reduce fiboding and flood damages in the downstream reaches of Krosno Creek.
i The model aiso predicts that the tofal runoff volume from the Pickering City Centre
� area would be reduced by almost 5% for the 2 year storm, and by more than 2% for
the 100 year storm. The reduction in flow volumes, especially for frequent storms,
i will benefit Krosno Creek antl the Hydro Marsh through reduced pollutant loadings
and reduced erosion potentiai.
5.2.2 Alternative 2: Enhanced Quantity Contral
(On-Site Control wifh 5rnm Reiee�tion and 50% lmperviousness)
The SWMM5 model for the Krosno Creek wafershed was also modified to reflect
Alternative 2, which represents future conditions in combination with current
stormwater management criteria as described in Section 5.1.2, along with a
maximum pre-development runoff coefficient of 0.50 to establish peak flow targets.
This alternative was represented in SWMM5 using the same approach described in
Section 5.2.�, but the re-developing portions of the City Centre sub-catchments were
assumed to be 50% impervious in re-caiculating the overall sub-catchment
imperviousness. The impervious area initial abstraction depths were maintained from
the SWMM5 model of Alternative 1 to.represent the required 5 mm on-site retention.
Calculations for the revised % ir�pervious and initial abstraction depths are included
in Appendix A.
The resulting reductions in peak flow rates and runoff volumes from the Pickering
City Centre area are summarized in Tables 5-3 and 5-4, respectively. Detailed
model output can be found in A�penc#ix A, with node locations illustrated on Figure
2-2.
Table 5-3: Change in Peak Flow—Alternative 2
� Change in peak flow relative to existing conditions
Table 5-4: Change in Runoff Volume — Alternative 2
5tud.y Area
Volume -17.7% -16.6% -95.6% -14.5% -13.7%
Reduction -
Change in runoff volume relative to
TMIG j THE MUNICIPAL INFRASTRUCTURE GROUP LTD
-12.9%
conditions
PAGE 29
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Pickering City Centre
STORMWATER MANAGEMENT STRATEGY
CITY OF PICKERWG
FINAL • APRIL 2015
PAGE 30
���
The SWMM5 model predicts that the redevelopment of Pickering City Centre,
applying the noted criteria, will reduce peak flow rates by up to approximately 7% to
8°lo for the 2 year through 100 year storms. The greatest reductions in peak flow
rates occur south of Bayly Street, downstream of the outlet from the large sewershed
located between Highway 401 and Bayly Street.
The model also predicts that the total runoff volume from the Pickering City Centre
area would be reduced by approximately 18% for the 2 year storm, and by
approximately 13 % for the 100 year storm.
The resulting peak flow rates and runoff volumes are also reduced considerably from
Alternative 1, This would also translate into greater reductions in flooding and filood
damages along Krosno Creek, and greater reductions in pollutant loadings and
erosion potential relative to Alternative 1.
5.2.3 Scenario 3: Enhanced Quantity and Vo/ume Control
(On-Site Control with 90mm Retention and 50% lmperviousness)
The SWMM5 model for the Krosno Creek watershed was also rnodified to reflect
Alternative 3, which represents future conditions in combination with the requirement
to apply a maximum pre-development runoff coefficient of 0.50 to establish peak flow
targets, and an increased on-site retention target of 10 mm (See Secfiion 5.1.3}.
This aiternative was represented in SWMM5 using the same approach described in
Sections 5.2.1 and 5.2.2. The % impervious values for the City Centre sub-
catchments were unchanged from the model created for Alternative 2 to represent
the maximum pre-development runoff coefficient of 0.5., The 10 mm on-site retention
was represented by increasing the impervious area initial abstraction depth to 10 mm
for the re-devefoping fractions of the City Centre SWMM5 model sub-catchments.
Calculations for the catchment % impervious values and initial abstraction depths are
included in Appendix P.. �
The resulting reductions in peak flow rates and runoff volumes from the Pickering
City Centre area are summarized in Tables 5-5 and 5-6, respectively. Detailed
model output can be found in Appendix A, with node locations illustrated pn Figure
2-2.
Table 5-5: Change in Peak Flow — Alternafive 3
-8.5%
-10.9%
-7.8%
-8.3% -7.0% -2.2%
-11.0% -10.2% -7.7%
-8.4% -18.9% -9.6%
-1.1% -1.3%
-7.7% -7.7%
-9.2% -0.7%
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�
� Pickering City Centre
STORMWATER MANAGEMENT STRATEGY
CITY OF PICKERING
FINAL • APRI� 2015
I Table 5-6: Change in Runoff Volume—Altemative 3
___ _ ___
100 Year
(56.8 mm)
-22.3% I -19.8% I -18.3% I -16.7% I -15.6% I -14.6%
to existing conditians
The SWMM5 model predicts that the redevelopment of Pickering City Centre,
applying the noted criteria, will reduce peak flow rates by up to approximately 11 %
for the 2 year storm, and up to approximately 8% for the 100 year storm. Note that
this represents a noticeable improvement over Alternative 2(5 mm on-site retention)�
for the 2 year storm, but oniy a small improvement for the 100 year storm.
The model also predicts that the total runoff volume from the Pickering City Centre
area would be reduced by more than 20 % for the 2 year storm, and by almost 15 %
for the 100 year storm. As with peak flows, the reductions in runoff volumes relative
to Alternative 2 are more pronounced for the smaller storms.
5.2.4 Scenario 4: Enhanced Quantify and Volume Contro/
(On-Site Control with 15rr�m Retenfion and 50% Imperviousness)
The SWMM5 model for the Krosno Creek watershed was also modified to reflect
Alternative 4, which represents future conditions in combination with the requirement
to apply a maximum pre-development runoff coefficient of 0.50 to establish peak flow
targets, and a further increased on-site retention target of 15 mm (See Section
5.1.4).
', This alternative was represented in SWMMS using the same approach described in
, the previous sections. The % impervious values for the City Centre sub-catchments
were unchanged from the models created for Alternatives 2 and 3 to represent the
� � maximum pre-development runoff coefficient of 0.5. The 15 mm on-site retention
; was represented by increasing the impervious area initiai abstraction depth to 15 mm
for the re-developing fractions of the City Centre SWMM5 model sub-catchments.
� Calculations for the catchment % impervious values and initial abstraction depths are
� included in Appendix �,. .
The resulting reductions in peak flow rates and runoff volumes from the Pickering
' City Centre area are summarized in Tables 5�7 and 5-8, respectively. Detailed
model output can be found in �.ppendix P,, with node locations illustrated on Figure
2-2. .
Table 5-7: Change in Peak Flow—Alternative 4
-11.3% I -10.5% I -8.8%
-15.0% I -13.2% I -12.1 %
-10.7% I -10.6% I -21.0%
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-2.8% -1.4%
-8.6°!0 -8.4%
-11.4% -10.4%
� peak flow relative to
-1.6%
-8.3%
-2.0%
� conditions
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STORMWATER MANAGEMENT STRATEGY
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FINAL � APRIL 2015
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52
Table 5-8: Change in Runoff Volume - Alternative 4
100 Year
(56:$ mm)
-27.1 % � -23.1 % � -21.0% � -18.9% � -17.5% � -16.3%
Change in runoff volume
The SWMM5 model predicts that the redevelopment of Pickering City Centre
applying the noted criteria, will reduce peak fiow rates by up to approximately 15 %
for the 2 year storm, and up to approximately 8% for the 100 year storm. This
represents a moderate improvement over Alternative 3(10 mm on-site retention) for
the 2 year storm, but only a slight improvement for the 100 year storm.
The r�odel also predicts that the total runoff volume from the Pickering City Centre
area would be reduced by approximately 27 % for the 2 year storm, and by more
than 16 % for the 100 year storm. As with peak flows, the reductions in runofF
volumes relative to Alternative 3 are more pronounced for the smaller storms.
5.2,5 A/ternative Eva/uation Summary
Table 5-9 summarizes and compares the results of the scenario evaluations.
Table 5-9: Alternative Evaluation Summary
For quantity control, Alternative 1 represents the current formalized criteria of
providing attenuation to reduce post-development peak flows to pre-development
levels for the 2 tlirough 100 year return period events. Alternatives 2 through 4
maintain this approach, but provide additional direction with respect to the pre-
development runoff coe�cient, which should be assumed as 0.50 or lower. Adopting
0.50 as the maximum pre-development runoff coefficient results in a significant
reductions in both peak flows and runoff volume, as compared to the basic formalized
criteria. These translate into reductions in the frequency and severity of filooding in
Krosno Creek. Furthermore, this approach e(iminates subjectivity in the evaluation of
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FINAL • APRIL 2015
pre-development conditions, which can have significant bearing on the effectiveness
of quantity control practices.
� For erosion and water balance, all of the scenarios provide for a minimurn 5 mm
runoff retentibn, or volume control. This approach is consistent with current minimum
criteria, and will yield a reduction in runoff volume relative to existing conditions. The
� 5 mm target can also be typicafiy achieved by a combination of the low impact
� development practices described in Section 4.2.1, irrespective of the proposed form
of development or local soil and groundwater conditions.
Exceeding the minimum by requiring 10 mm or 15 mm runoff retention wiil yield
furfher and significant reductions in runoff volume generated over the Pickering City
Centre area, with corresponding reductions in pailufant loadings to Krosno Creek and
the Hydro Marsh, and improvements in the stability of the more natural downstream
channel reaches. The increased on-site runoff retention depths of 10 mm and 15 mm
also reduce peak flows in Krosno Creek relafive to the formalized 5 mm criterion,
particular(y for more frequent storms.
' However, achieving 10 mm or 15 mm runoff retention can be challenging for some
� 'forms of development, particularly within the dense urban setting that is envisioned
; for Pickering City Centre, possibly yielding the need for an extensive form of
� rainwater harvesting, such as greywater reuse.
All of the options satisfy or exceed current water balance and erosion requirements.
For water quality, individual developments would be required to demonstrate
conformity to the 80% TSS removal requirement, with credit given for the extent of
volume control that will partially address the target.
5.3 City Street Strategies
iAs described in Section 4.2.2, an opportunity exists to incorporate an LID solution
into right-of-ways (ROWs) within Pickering City Centre, primarily to manage runoff
generated from the ROW. However, the feasibility of implementation is dependent on
�'� numerous factors which can only be fully evaluated at a detailed design stage with
' specific local data regarding soils, water table depth, the presence of uti(ities and
other services, as well as• the desired form and function of the roadway and
i boulevard in that location.
The analysis of a ROW LID solution presented in this report is intended to assist the
City for future decision making purposes, in regards to the potential stormwater
management benefits that could be realized with varying degrees of implementation.
The example described in Sectimn 4.2.2 postulated an LID configuration within the .
ROW that could store the runoff generated over the ROW area from a 25 mm storm
event.
The existing conditions SWMM5 model of Krosno Creek was modified in a similar
manner to the alternatives evaluated in Section 5.2 to assess the effectiveness of
LIDs on City streets. The existing and planned road right-of-ways within each model
sub-catchment covering the Pickering City Centre area were measured. These areas
were assigned an initial abstraction depth of 25 mm and the overall catchment
impervious area initial abstraction depth was recalculated. Calculations for the right-
of-way areas and initial abstraction depfhs are included in ,�ppendix e4. To better
understand the effectiveness of LIDs installed in City streets, the SWMM5 model
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FINAL � APRIL 2015
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54
created for this alternative did not consider the future development (and,associated
SWM controls) envisioned within the City Centre area.
The resuiting reductions in peak flow rates and runoff volumes from the Pickering
City Centre area are summarized in Table 5-10 and Table 5-11, respectively.
Detailed model output can be found in Appendix A.
Table 5-10: Change in Peak Flow— LID on City Streets
-5.8% I -4.4% I -3.5% � -0.7% � -0.6% � -0.5%
-5.9% -4.1 % -3.1 %. -2.1 % -1.4% -1.1 %
-3.9% -3.3% -5.0% -2.5% -2.3% -2.2%
Change in peak flow relative to existing cond
Table 5-11: Change in Runoff Volume — LID on City Streets
-8.5% I -5.9% I -4.9% I -4.0% I -3.5% I -3.1%
Change in runoff volume re/ative to existing conditions
The analysis demonstrates that the application of LIDs to all ROWs within the _�
Pickering City Centre area would yield a moderate reduction in downsfream peak
flow rates for the more frequent storms, but a negligible reduction in peak flow rates
for the 100 year and Regional storms. The reduction in runoff volume would be �
beneficial with respect to quality, erosion, and water balance criteria. However, as the �
analysis is premised on fufl implementation throughout Pickering City Centre, any
lesser degree of implementation would yield a proportionate reduction in the benefit �
to be realized. I
5.4 Storrnwater Management in Public �paces
The Downtown Pickering Vision and Redevelopment Framework (June 2013) states
that:
"The City of Pickering remains a leader in sustainability and the downtown is
an excellent area to advance sustainable city building objectives and �
demonstrate sustainability initiatives."
In addition to the exploration of LID practices within the ROWs described in Section
5.3, the feasibility of incorporating stormwater management infrastructure into other
public spaces can also be considered, as a means to advancing the sustainability
vision for the City Centre area.
In general the opportunities will become available as redevelopment proceeds, and
the City must be cognizant of the potential for these opportunities to utilize
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�
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FINAL � APRIL 2015
stormwater as a resource, and set in place the pianning mechanisms by which
feasibility can be evaluated and, ultimately, implemented.
An example of integrating infrastructure into public spaces within an urban core is the
development of Sherbourne Common. Sherbourne Common is an award-winning
public park in the heart of the East Bayfront precinct of Toronto's waterfront. The park
serves as an amenity to the new community of mixed residential, employment, and
commercial space, and simultaneously contains elements of the stormwater
management infrastructure servicing the broader community. The services within the
park include a UV treatment facility incorporated into the park pavilion, and the
utilization of treated runoff and lake water to supply a series of public art features.
Figure 5-1: Sherbourne Common Water Features
5.5 Special Considerations fnr the Pickering Town Centre
As no#ed in Section 2.4, the City worked with the owners of the Pickering Town
Centre to incorporate approximately 12,350 m3 of flood storage through the re-desigri
of the south parking lot area during an expansion to the Pickering Town Centre in the
early 1980's. The approximate Figure 5-2: Pickering Town Centre Vision
storage area is illustrated in
Figure 2-3.
The Downtown .Pickering Vision
and Redevelopment Framework
(June 2013) envisions
redevelopment in this area, and
the figures in the report illustrating
the vision show a number of new
buildings in the sxisfing flood
storage area between Pickering
Parkway and the existing
Pickering Town Centre buildings
(Figure 5-2).
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STORMWATER MANAGEMENT STRATEGY
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PAGE 36
l�l';
Without special considerations, new development in the existing south parking lot at
the Pickering Town Centre could consume the current flood storage volume,
potentially increasing peak flow rates in Krosno Creek south of the CNR and
increasing flood levels upstream of Highway 401. Note that all of the stormwater
management alternatives evaluated in Sections 5.2 and 5.3 assumed that the
existing flood storage af the Pickering Town Centre would be preserved in some
form, in addition to the on-site storage throughout the City Centre area needed to
achieve the peak flow targets associated with the different alternatives.
The SWMMS model of the Krosno Creek watershed was used to assess the
importance of the existing storage in managing flow rates and flooding in Krosno
Creek. The existing conditions model was modified by removing the existing storage
volume and the various storm events were simulated. To be conservative, no other
redevelopment (which will reduce runoff volumes and peak flow rates) was
considered in the SWMM5 model.
The analysis d.etermined that, with the storage removed, peak flow rates in the flood
prone reaches of Krosno Creek south of Bayly Street would increase by up to 7%
during tlie 100 year storm. More significantly, the maximum water level on the
upstream side of Highway 401 would increase from 84.66 m to 85.27 m during a 100
year storm.
Although the loss of the existing flood storage at the Pickering Town Centre may
increase peak flow rates and flood levels in Krosno Cresk, redevelopment of the j
overall Pickering City Centre area, with appropriate stormwater management �
controls, is expected to decrease peak flow rates and runoff volumes in Krosno
Creek. However, it is expected that full build-out of the Pickering City Centre vision i
(and full achievement of the predicted stormwater management controls) is expected —�
to take several decades. .
Regardless, a finai SWMMS model was created to represent full implementation of
the envisioned redevelopment and intensification in Pickering City Centre; with the
existing flood storage at the Pickering Town Centre removed. The SWMM5 modef
created for Alternative 2(peak flows controlled to pre-development levels with a
maximum pre-development runoff coefficient of 0.5, 5 mm on-site volume retention)
was used as the basis for this scenario. The SWMM5 model output is summarized in
Table 5-12.
Table 5-12: Pickering Town Centre Storage Implications
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With the existing flood storage preserved, the maximum water level upstream of the
Highway 401 culvert for the 100 year storm drops from 84.66 m under existing
conditions to 84.59 m with implementation of Alternative 2. When the flood storage
at the Pickering Town Centre is removed from Alternative 2, the expected flood levei
upstream of Highway 401 increases to 85.25 m, which remains a significant increase
over existing levels.
The SWMM5 model predicts'that under full build-out of the City Centre vision with the
suggested stormwater management plan, the elimination of fhe existing flood storage
at the Pickering Town Centre would increase peak flows and flood levels upstream of
Highway 401, but flows and flood leve(s would remain slightly below existing
conditions in the most flood prone reaches downstream of Bayly Street.
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�' �' • •' i • � ' • • �'
. ' ' •
PAGE 38
:
As described in Section 1.1, the objective of this study is to define a stormwater
management strategy for the Pickering City Centre area that will complement the
vision for the City Centre. The intent is to establish an appropriate mix of stormwater
management elements that, through implementation as part of redevelopment, v,iill
serve to better mitigate the impacts of urbanization and prioritize quality of life
through the principles of sustainability.
6.1 Stormwater Management Criteria
Section 5 of this document provides a series of scenarios that embody the latest
approaches in stormwater management, with each simulated to quantify the extent of
improvement that could be achieved in terms of quantity, quality, erosion, and water
balance requirements. �
The analyses demonstrate the merits of the current quantity control criteria in
combination with the stipulated maximum pre-development runoff coefficient of 0.50.
For volume control, the analyses also make ciear that enhanced volume control
targets greater than the current 5 mm minimum will yield further reductions in the
runoff volumes and peak flow rates generated by the Pickering City Centre area.
Enhanced volume control is also consistent with the principles of sustainability
inherent in the vision for Pickering City Centre, and will contribute substantially to
improved downstream water quality.
Based on these findings, it is recommended that Alternative 2 be adopted as the
basis for the stormwater management strategy for Pickering City Centre, and applied
as criteria to all development and redevelopment within the Pickering City Centre
area. Alternative 2 entails:
� Con�rol of post-development peak ilows to pre-developmenfi levels with ar�
assumed maximum pre-development runofF caefficient of 0.50;
■ Volume controf via lovv irrapact development to achieve a runoff retention
�argefi of 5 mm; and,
6 I�afier� quality treatsnent to �chieve the TRC�,/MQE requirement (80% TSS
removal). � .
6.2 Site Specific Cri#eria for the Pickering Town Gentre Lands
As described in �ection 2.4, the Pickering Town Centre currently provides storage
within the southern parking lot, which is effective in reducing peak flow rates in the
downstream reaches of Krosno Creek, and reducing flood levels upstream of the
Highway 401 culvert. Up to 8,800 m3 of floodwater is expected to be stored on the
soufih parking lot during the 100 year return period storm.
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The analyses documented in Section 5.5 found that if the existing fiood storage was
removed (in the absence of other improvements and redevelopment in Pickering City
Centre), flood levels on the upstream side of Highway 401 would increase by up to
61 cm, and peak flow rates in the flood prone reach of Krosno Creek downstream of
the Highway 401/CNR culverts could increase by as much as 7%_ during a 100 year
storm event.
The earlier Stormwater Managemenf Study (Simcoe Engineering, 1984) indicates
that the flood storage on the south parking lot at the Pickering Town Centre
(�2,350 m3) was created as a result af an agreement between the City of Pickering
and the owners of the Pickering Town Centre during the expansion that occurred in
the early 1980's.
There is therefore a reasonable expectation that the previously agreed upon flood
storage at the Pickering Town Centre would be preserved in any re-development of
the site.
if is therefore recornmended that any redevelopment in the flood storage area
identified in Figure 2-3 preserve the existipg flood storage voluiroe on the sit�.
Ifi is furfiher recornmendee� that n�uv developmeo�t in the existing flood storage
area be flood proofed to the predic�ed 100 year flood level (84.66 m) plus a
reasonable freeboard dep�h.
If significant re-development in the City Centre Area has occurred prior to re-
devefopment within the existing flood storage area at the Pickering Town Centre, the
required flood storage volumes and minimum flood proofing elevations could
potentially be relaxed.
Ideally, the storage should be replaced at a similar elevation as existing (between
84 m and 85 m). At a minimum, the storage must be located above the invert of the
Highway 401 culvert (81.5 m). If irnplemented on a site by-site basis, it is expected
that the required flood storage (in addition to the storage required to achieve the
quantity and quality criteria listed in �ection 6.1) would be provided in a large
underground vault, likely within each building footprint. It is estimated that the
resulting underground storage system could cost between $4 Million and $6 Million
for a typical 1 ha site located on the south parking lot at the Pickering Town Centre
(See Appendix �).
A comprehensive functional servicing and stormwater management plan is
recommended for the entire Pickering Town Centre lands to determine how best to
implement centralized starmwater management and replacement flood storage for all
planned redevelopment. It is expected that centralized storage can be provided
much more economically than preserving the flood plain storage and providing
stormwater controls within each individual future building site. .
! In addition to the comprehensive functional servicing and stormwater management
plan, short term strategies are also recommended to reduce the current risk of
Iflooding at the Pickering Town Centre. Recall from Section 2.4 that the Pickering
Town Centre was reported(y flooded during the severe storm of August 2005, and
continues to be at risk of flooding for very large storm events. Backflow preventers
iand/or other measures are recommended to protect the Pickering Town Centre from
surcharging conditions in the sewers currently servicing the building.
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STORMWATER MANAGEMENT STRATEGY
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PAGE 40
� �
6.3 Aspirational Targets
As noted, enhanced volume control (1Q mm or 15 mm) can further improve water
quality; erosion and flooding conditions in Krosno Creek. Therefore, although the
recommended criteria within Pickering City Centre includes a minimum 5 mm farget
for volume control, opportunities to incent enhanced volume control "approaches as
part of redevelopment should be explored.
Incentives are particularly relevant with the recognition that achieving 10 mm or
15 mm of runoff retention can be challenging for some forms of development, and
can require an extensive form of runoff reuse, such as greywater reuse, that can
substantially impact the cost and potentially feasibility of a development project.
To some degree, and as noted in Section 3.2, volume control can satisfiy water
quality treatment requirements which would otherwise need to be addressed via an
oil-grit separator or similar hard infrastructure practice. The effectiveness of volume
control with respect to water quality should be demonstrated for each individual
development, to the satisfaction of the City, in order to offset or even eliminate other
water quality infrastructure requirements.
There are other incentives to encourage the adoption of aspirational targets.
According to the U.S. Environmental Protection Agency, there are five main types of
incentive programs (Water Environment Federation, January 2013):
1. Development incentives can include streamiined permitting processes, {
decreased fees, zoning upgrades, and reductions in other regulatory '
requirements. One established mechanism relates to Section 37 of the Planning �
Act, which provides the municipality with flexibility in the administration of zoning
provisions to support community initiatives. '
2. Grants can be made available to development proponents and community
groups to achieve aspirational targets. Funding can be provided directly to
proponents, or indirectly via sustainable design competitions or outreach
initiatives.
3. Rebates and installation financing can include funding, tax credits, low interest
financing, or reimbursements for. those development proponents that endeavour
to achieve aspirationai targets.
4. Awards and recognition programs can be used to reward innovation and increase
awareness of the merits of sustainable designs.
5. Stormwater utility fee discounts, which are applicable in jurisdictions that
presently administer a stormwater fee program. As with many municipalities :in
ttie GTA, the introduction of a stormwater fee program within the City of Pickering
could facilitate broader adoption of stormwater and conservation related
sustainability approaches.
These incentive approaches can also be applied to other aspects of sustainabie
development such as energy conservation or active transportation.
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y � ' • �'
Section 5.4 presents an approach to and the corresponding benefits that could be
realized through the implementation of LIDs within existing and planned right-of-ways
as the Pickering City Centre area redevelops. It is recommended that the renewal
and revitalization of individual streets explore the feasibility, costs, and benefits of
implementing LIDs within their construct to further improve the overall sustainabifity of
the community.
Similarly, Section 5.5 describes the opportunity to integrate stormwater management
infrastructure into public spaces such as parks, squares, and related amenities. As
the vision for the public spaces are further articulated, it is recommended that
principles of infrastructure integration be maintained as a priority. Blocks of
development could likewise expiore integration of fhe infrastructure needed to
address site specific requirements into adjacent pubiic spaces, to achieve both the
site targets in addition to the targets for the public space.
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Pickering City Centre
STORMWATER MANAGEMENTSTRATEGY
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FINAL • APRIL 2D15
� Summary
The Municipal Infrastructure Group was retained by the City of Pickering to establish
a Stormwater Management Strategy to complement the re-development and
intensification of the Pickering City Centre envisioned in the report Downtown
Pickering — A Vision for Intensification and Framework for Investment (Urban
Strategies, June 2013).
A number af alternative stormwater management strategies were analyzed and
evaluated in the development of the strategy, ranging from business as usual
(adopting current formalized criteria) to widespread and intensive application of
emerging low-impact-development practices to significanfly improve water quality,
erosion and flooding conditions in Krosno Creek, to which the majority of the study
area drains.
The recommended .Stormwater Management Strategy includes the following criteria
and recommendations:
a Gontrol of post-developmen4 peak flow rates to pre-development levels. A
maximum runoff coefficient of 0.5 shouls9 be used to represent pre-
developrr�ent conditions, regardless af how much impervious cover
currently exists on a redevelopment site;
■ 12etention of the runoff fram up to a 5 rr,m storm event on site for infiltration
or r�-use (i.e. no minor or major system flow from a site for up to a 5 mm ,�
storm};
� Enhanced water quality protection (80% TSS IZemoval), v✓ith consideration i
given fio fihe vvafier qualit� benefits associa#ed with on-site runoff re�ention; ,
�
� Incentive programs to encourage development to achieve voluntary on-site
runoff reien#ion targets of 10 mm to 15 mm;
� Implerraentafiion of Lovu Irripact Development practices within public right-of-
ways and integra4iori of innovative stormwater managemer�t practices with
public open space, where feasible and appropriate; and, �
•�reparation and implementation of a comprehensiv� functional servicinc�
and stormvvater managernent plan for �he Pickering Towrn Centre lands to
preserve fihe existing flood sfiorage and pro�ect new develapment fram
filooding in the existing flood storage area at the south parking lot of the
Pickering Town Centre.
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STORMWATER MANAGEMENT STRATEGY
CITY OF PICKERING
FIIVAL � APRIL 2015
! .-
,.�. � �
MMM Group Limited, April 2009. `StormwaterManagement MasterPlan,
? Frenchman's Bay Watersheds.' Prepared for City of Pickering.
1 �
Ontario Ministry of Natural Resources, 2002. 'Technical Guide — River & Stream
Systems: Flooding Hazard Limit.'
Ontario Ministry of the Environment, 2003. "Stormwater Management Planning and
Design Manual.' Queen's Printer for Ontario.
Simcoe Engineering Group Limited, 1984. `Stormwater Management Study.'
Prepared far City of Pickering.
The Municipal Infrastructure Group, 2014. 'Project File Repori — Krosno Creek F(ood
Reduction Project.' Prepared for Cityof Pickering.
; Toronto and Region Conservation Authority, 2002. `Krosno Creek Preliminary
Stormwater Management Strategy'. Prepared in association with City of
j Pickering and Ontario Power Generation.
i"
� Toronto and Region Conservation Authority, 2002. `Krosno Creek Floodplain
i Mapping Study.' Prepared in association with City of Pickering.
' Urban Strategies, 2013. `Downtown Pickering — A Vision for Intensification and
Framework forinvestmenY. Prepared for City of Pickering.
�
�
�
; . �
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Pickering City Centre
STORMWATER MANAGEMENTSTRATEGY
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1, � � � � �
SWMMS Model Input and
Output
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64
___1_____
� � � �
The built form vision for powntown Pickering creates a foundation for urbanization of the Downtown to 2031 and beyond, Iaying out an enhanced
street network, new public spaces, destinations, and a range of opportunities for intensification and new development. The vision forms the basis for
downtown mobility, public realm, built form, land use, placemaking and sustainability systems as well as precinct specific policies, each detailed in
individual chapters within the framework.
'The following are key features of the built form vision:
�,, The Civic PrecinCt is the downtown's cultural and
,'� institutional hub with destinations and distinct public
realm treatment.
� 2�} An extraordinary public realm is formed through
new public spaces that pbpulate the downtown. A
variety of small and large gathering places are within
a five minute walk anywhere in the downtown
,, 3�j A gateway at Kingston & Liverpool Road is
`' characterized by distinct buildings and public plazas
at each of the four corners.
�q.l Tt1e TPansit Hub at the heart of an enhanced transit
system is a waiting area, meeting place and entry-
way to the downtown. It is integrated with the rest of
downtown through streets and pedestrian-ways, and
surrounded by exceptional buildings.
;� PiCkering Parkway is extended west of Liverpool
Road. It is a key transitway, connecting Downtown
from east to west. .
�J Distinct tall buildings line Highway 401,
signallingthat Downtown is the core of Pickeringto
surroundingareas ofthe City.
( 7� Enhanced connectivity is achieved by new bridges
and street connections.
�� New DeSti11at1011S are supported to enhance the
�_s
range of activities, amenities and economic vitality of
� fhe downtown.
cn
• � '' - � � ! � V � 1 � ' y •"
iv DO�lVNTOWN PICKERING A VISION FOR INTENSIFICATION AND FRAMEWORK FOR INVESTMENT
Pickering City Centre
STORMWATER MANAGEMENTSTRATEGY
CITY OF PICKERING
� . • � . �
Existing Conditions
TMIG � THE MUNICIPAL INFRASTRUCTURE GROUP LTD
m
�
•.
, i
�_.- _. __ -� ____ _ __ ----- f1-- - - -_ .�
Project: Pickering Downtown SWM
Project No: 12150 �
Date: 07-Jun-13
Subcatchments Parameters for powntown Pickerine
Scenario: Ezisting Conditions , PCSWMM output'
100 Year 1hr 50 Year lhr 25 Year ihr 10 Year ihr 5 Year ihr AES 2 Year ihr AES
AES (56.8mm) AES (51.4mm) AES (45.9mm) AES (38.Smm) (32.6mm) (23.8mm) Hazel Storm
Flow Dstore Dstore Runaff Runoff Runoff Runoff RunofF Runoff Runoff
Area Width Slope Imperv
Name (ha) (m) Length (/� (�� N Imper N Perv Imperv Perv Volume Volume Volume Volume Volume Volume Volume
(m) (mm) (mm) (ML=10^6 L) (ML=10^6 L) (ML=10^6 L) (ML=10^6 L) (ML=10^6 L) (ML=10^6 L) (ML=10^6 L)
sub_12 1.82 178.6 101.7 1.0% 81.9S 0.0137 0.4164 Z 8.7 0.86 0.77 0.67 0.55 0.46 0.32 4.52
sub_13 2.98 293.4 101.7 2.1% 81.99 0.0137 0.4164 2 8.7 1.43 1.28 1.12 0.92 0.76 0.54 7.52
sub_17 11.38 3355.6 339 1.5% 57.89 0.0137 0.4164 2 8.7 3.86 3.41 2.97 2.44 2.04 1.46 24.9
sub 18 11.10 3275J 33.9 Z.5% 45.84 0.0137 0.4164 2 8.7 3.87 3.34 2.82 2.17 1.7 1.14 23.27
su6_l9 2.59 254.6 101.7 4.0% 81.68 � 0.0137 0.4164 2 8.7 1.23 1.1 0.97 0.79 0.66 � 0.47 6.51
sub 20 15.75 1548.5 101.7 1.5% 97.00 0.0137 0.4164 2 S.7 8.45 7.61 6,74 5.59 4.67 331 42.51
sub 21 10.20 1002,5 101.7 1.9% 97.00 0.0137 0.4164 2 S.7 5.49 4.94 4.38 3.63 . 3.03 2.15 27.6
su6 23 231 651.7 33.9 1.9% 62.59 0.0137 0.4164 2 8.7 0.99 0.87 0.76 0.6 0.48 0.33 5.64
sub 25 3.39 999.4 33.9 0.7% 76.98 0.0137 0.4164 2 8.7 1.57 1.4 1.22 0.99 0.82 0.58 8.39
sub 26 6.23 1536.5 33.9 3.1% 61.26 0.0137 0.4164 2 8.7 2.53 2.22 1.92 1.52 1.23 0.85 14.23
sub_27 7.03 691.1 101.7 1.2% 81.78 0.0137 0.4164� 2 8.7 338 � 3.02 2.65 - 2.16 1.79 1.25 17.92
sub 28 532 523.1 101.7 1.1% 81.68 0.0137 0.4164 � S.7 2.53 2.26 1.95 1.62 1.34 0.94 13.32
sub_3 1.08 956.4 11.3 1.4% 86.79 0.0137 0.4164. Z 8.7 0.56 0.5 0.44 036 0.3 0.21 2.87
sub_30 7.42 729.5 101.7 1.1% 81.68 0.0137 0.4164 2 8.7 3.56 3.17 2.79 2.27 1.88 1.32 15.87
sub_31 Z.92 287.0 101.7 1.6% 51.68 0.0137 0.4164 2 8.7 1.39 1.24 1.09 0.89 0.74 0.52 7.3
sub 32 2.97 292.5 101.7 1.1% 81.68 0.0137 0.4164 2 8.7 1.43 1.27 1.12 0.91 0.75 0.53 7.57
sub_39 7.63 750.4 101.7 1.9% 81.68 0.0137 0.4164 2 'SJ 3J 3.3 29 236 1.95 137 19.61
sub_4 6.85 674.0 101.7 2.4% 97.00 0.0137 0.4164 2 8.7 3.65 3.29 2.92 2.43 2.04 1.45 18.58
sub_40 11.47 1128.0 101.7 ' 4.3% 81.68 0.0137 0.4164 2 8.7 5.59 4.95 4.38 3.57 2.95 � 2.07 29.25
sub 48 7.ZS 715.8 101.7 3.3% 20.62 0.0137 0.4164 2 8.7 � 137 1.12 0.91 0.66 0.5 0.34 10.48
suh_5 12.54 5547.0 22.6 8.9% 86.79 0.0137 0.4164 2 8.7 639 5.72 5.04 4.13 3.41 2.43 33.33
sub_6 13.96 6175.5 22.6 4.7% 86.79 0.0137 0.4164 2 8.7 7.21 6.46 5.7 4.68 3.87 2.7 37.05
sub 61 1.77 15641 11.3 1.2% 86.58 0.0137 0.4164 2 8.7 3.43 3.03 2.63 2.1 1.71 1.17 18.81
sub 65 1.48 1309.9 11.3 1.2% 86.58 0.0137 0.4164 2 S.7 0.77 0.69 0.61 0.5 0.41 0.29 3.93
sub 66 0.82 7263 11.3 � 1.4% 86.79 0.0137 0.4164 2 8.7 0.42 0.38 033 0.27 0.23 0.16 2.18
sub 67 538 529.3 101.7 2.4% 97.00 0:0137 0.4164 2 S.7 2.87 2.58 2.29 1.91 1.6 1.14 14.59
sub 7 8.23 808.9 101.7 2.4% 51.68 0.0137 0.4164 2 8.7 3.98 3.55 3.12 2.55 2.1 1.48 21
TOTAL 171.89 -. 75.5 � 82.5 73.5 64.5 52.6 43.4 30.5 441.8
City of Picfcering
Krosno Creek D6version Project
TMIG Project 12150
PCSWMM Model Output
. . . ,
Maximum Flow Rate
Location Conduit 2 5 10 25 . 50 100 Hazel
Highway 401 34 1 10.01 13.40 15.72 17.12 17.50 17.86 17.75
Bayly Street
Weir Flow KC CJ44 HC 0.00 0.00 0.00 0.00 0.00 0.03 0.32
Culvert Flow KC CJ44 9.84 13.05 15.18 16.93 17.55 18.01 17.87
Total Flow ADD � 9.84 13.05 15.18 16.93 17.55 18.04 18.19
Downstream Bayly Street KC_CJ43 12.73 16.96 19.91 22.50 24.09 25.44 24.87
Morden Lane
Weir Flow KC CJ37 HC 0.00 1.57 5.71 7.25 9.13 10.92 11.23
Culvert Flow KC CJ37 12.89 15.67 16.39 16.65 16.79 16.81 17A2
Total ADD 12.89 17.24 22.11 23.89 25.92 27.73 28.25
Reytan Boulevard
Weir Flow KC CJ29 HC 0.10 0.38 . 4.76 7.71 9.63 1022 13.15
Culvert Flow KC CJ29 12.75 14.23 14,84 15.05 15.14 15.42 15.30
Total ADD 12.85 14.61 19.60 22.76 24.77 25.63 28.45
Alyssum Street �
Weir Flow KC CJ25_HC 0.25 2.83 8.52 12.79 15.52 15.64 21.32
Culvert Flow KC CJ25 11.69 12.17 12.19 12.12 12.02 11.93 11.72
Total ADD 11.94 15.00 20.71 24.91 27.54 27'.56 33.04
Sandy Beach Road North Culvert
Weir Flow KC CJ20 HC 0.00 1.07 7.01 11.38 14.14 13.99 20.89
Cuivert Flow KC CJ20 11.97 13.57 13.54 13.42 13.38 13.31 13.28
Totai ADD 11.97 14.64 20.55 24.80 27.52 27.30 34.17
Confluence with East Tribut KC CA 16.37 21.79 28.62 35.99 41.18 43.50 48.51
Sandy Beach Road South Culvert
Weir Flow KC CJ7 HC 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Culvert Flow KC CJ7 17.34 23.44 29.83 37.64 43.28 46.65 53.41
Total ADD 17.34 23.44 29.83 37.64 43.28 46.65 53.41
Outlet to Frenchman`s Bay KC_CJ.4 16.35 20.82 25.09 29.93 33.14 35.54 61.48
.•
_-- i ;
_. _.. �- --- --_ �__ -__. -'-__
v
o '
City of Pickering
Krosno Creek Diversion Project
TMIG Project 12150
PCSWMM Model Output
Existing Conditions
Maximum Hydraulic Grade Line (m)
Location Node 2 5 10 25 50 100 Hazel
Sandy Beach Road North Culvert - Downstream KC_J19 76.77 77.04 77.27 77:40 77.47 77.47 77.63
Sandy Beach Road North Culvert - Upstream KC J20 77.17 77.55 77.72 77.79 77.83 77.83 77.89
Alyssum Street Culvert - Downstream KC J24 77.25 77.61 77.82 77.94 78.01 78.01 78.15
Alyssum Street Culvert - Upstream KC J25 77.95 �� �78�*1,�1�� ; , �� =78 22 ��� �t `� 78�28�` �`� h�; � �78�31 �' � �����78 �31 ,,;, �',78 35,` x
Reytan Boulevard Culvert - Downstream KC J28 77.97 78.11 78.23 78.29 78.32 78.33 78.38
Reytan Boulevard Culvert - Upstream KC J29 �� 78;��7�9�a � �;; �79�,00 ��� ��� �,79�14$�� a ���79�20 ��k �t ��7t9u2����� tx�,�,7$9�25� ;� � 79``29° °
Morden Lane Culvert - Downstream KC J36 78.93 79.19 79.61 79.64 79.64 79.70 79.74
Morden Lane Culvert - Upstream KC J37 ;� �80.�04�� � " ,80 4'� �� d..80 56 ��� ,r, �80'62 � �� 80r66�r�, ������80�69� .� � 80;�70 ���;
Bayly Street Culvert - Downstream KC J43 80.38 80.76 80.91 81.02 81.08 81.13 81.12
Bayly Street Culvert -Upstream � KC J44 80.99 81.40 81.66 $1.87 81.95 `�`�82�02 �: ; 82� 06 ,���
Highway 401 / CNR Culverts - Downstream KC J48 81.67 81.67 81.86 82.01 82.09 82.14 82.18
Highway 401 / CNR Culverts - Upstream 8 82.75 83.43 84.00 84.39 84.55 84.66 84.64
� "' �� � # �t k� flood damages incurred
TMIG � THE MUNICIPAL INFRASTRUCTURE GROUP LTD
Pickenng City Cenfre
STORfJ�WATER MANAGEMENT STRATEGY
CITY OF PICKERING
I, � �;. � �
Post - to - Pre Control
5 mm On=Site Retention
71
�
�_..� _.._L__.. ._.___._.. _:_�
Project: Pickering Downtown SWM
Project No: 12150
Date: 07-Jun-13
Su6catchments Parameters for Fufure Conditions in Downtewn Pickerine
Scenario: 5.mm on?site retention;'no;,quantity control ?,' �; � PCSWMM output
100 Year 1hr 50 Year 1hr 25 Year 1hr 10 Year 1hr 5 Year 1hr AES 2 Year 1hr AES
AES (56.8mm) AES (51.4mm) AES (45.9mm) AES (38.Smm) (32.6mm) (23.Smm) Hazel Storm
r
At'ea to be +� � Original z,'Revisetl� '
developed Original =� Rewsed� , t�� �iu -� , Runoff Runoff Runoff Runoff Runoff Runoff Runoff
� � Dstore ,, Dstorex * �
Su Area (ha) Imperv � k Imperv� � � Volume Volume Volume Volume Volume Volume Volume
Catchmetn (ha) � ���7 �� Imperv �Impent �, � � � � � � � �
(targeted at (%) �r' s(%) i (mm) �, (,��m) (ML=10 6 L) (ML=10 6 L) (ML=10 6 L) (ML=10 6 L) (ML=10 6 L) (ML=10 6 L) (ML=10 6 L)
80% imp.) ?s �, ,� � ,� � ' �`
M f
sub 12 1.82 1.68 81.99 ,80�15,�'u�� 2� ,�4 8� r; 0.82 OJ2 0.63 0.51 0.42 0.28 � 4.44
sub_13 2.98 2.98 81.99 �80'00 � 2 S�Ox ��;,' 1.35 1.2 1.04 0.84 0.69 0.47 738
sub 17 11.38 0.81 57.89 � s;59:47+" h; 2 ��*�2x'Z z�' " 3.94 3.48 3.0�} 2.49 2.09 1.49 25.18
sub 18 � 11.10 4.02 45.84 � '5,�,�21� ��� 2 ��3 1�ti�r rt'� 4.41 3.86 3.31 2.59 2.07 1.39 25.21
sub_19 2.59 132 81.68 f 3� ' 80 82" x; 2 3 5� 1.2 1.07 0.93 0.76 0.63 0.44 6.45
�
sub_20 15.75 8.73 97.00 � 8��57,u� � � 2 t � 3.7 �`�, ' 7.68 6.85 6.02 4.92 4.06 2.82 40.43
sub 21 10.20 3.44 97.00 s 91'r26 " 2 + 3 0�� �; . 5.2 4.66 - 4.11 3.37 2.8 1.96 26.82
sub_23 �2.31 0.00 62.59 62=59 � J;�, 2 � 2.0 ��: 0.99 0.87 OJ6 0.6 0.48 � 0.33 5.64
sub_ZS 3.39 2.41 75.98 ,€ 7413 , 2 41 �a �`•, 1.56 139 1.21 0.98 0.8 0.55 8.45
sub_26 6.23 1.71 61.26 66�41'`,. � 2 �:8 :� 2.65 2.33 2.02 1.61 1.3 0.9 14.67
sub 27 7.03 2.48 81.78 81;15 2 ,� 3,1 4'. 3.31 2.95 2.58 2.1 1J3 1.19 17.82
sub 28 5.32 5.32 81.68 y 80' OOi 2 ' S 0 2.4 2.13 1.85 1.5 1.22 0.83 13.09
�
sub} � 1.08 0.29 86J9 z` �84� 96�, ��„.� 2 �2:8 �,���. 0:55 0.49 0.43 0.35 0.29 0.2 2.84
sub 30 7.42 0.77 81.68 � g,1�5,1�`� '' '�r
_ �� � 2 ' 2'3�� ; 3.54 _ 3.15 2.77 2.26 1:86 1.3 18.84
sub_31 2.92 0.83 81.68 ��81? 20+� �' 2 �r 2 9 �r 1.36 1.22 � 1.07 � 0.87 OJ2 � 0.5 7.26
� �, s� -��� � ta� t �.��`'�'t,:
sub_32 2.97 0.00 81.68 �, �81�681 2 v s��20��� t 1.43 1.27 1,12 0.91 OJS 0.53 7.57
sub_39 7.63 7.63 81.68 k x; 80 00�� ¢. 2 v 5:0� '�; 3.51 3.11 2J1 2.18 1J8 1.2 19.32
sub 4 6.85 5.88 97.00 ' k382?42� 2 4 6° �s� �= 3 2.69' 2.38 1.96 1.63 1.13 17.1
5� � .
sub 40 11.47 11.47 81.68 �"� 80 00 ' 2 `� 5 0��� , 5.3 4.7 4.1 3.3 2.69 1.82 28J9
sub_48 7.28 0.00 20.62 ��+�720 62 ��j 2 ��� �2 0�����: 1.37 1.12 0.91 0.66 0.5 0.34 10.48
sub 5 12.54 0.00 86.79 ��86�75p����n 2 �s „��2�0�¢ �", 6.39 5.72 5A4 4.13 3.41 2.43 3334
`y Rs��` '� � �x�
sub 6 13.96 0.00 86.79 ;`��86'�l9'�~ a`� 2 ���"� `��2`�0�'� �� i.21 6.46 5J 4.68 3.87 2J 37.06
� u ir 7"
sub 61 1.77 030 86.58 '�'85�46 � 2 "�� � 2�5��` }' 3.54 3.13 2J1 2.18 1.77 1.21 19.21
sub 65 1.48 0.08 86.58 '+��86�24� �' 2 Y���' 2�2�?, �. OJ6 0.68 0.6 0.49 0.41 0.28 3.93
1 ��h�§�rs-�x � � �a "
sub 66 0.82 0.22 86J9 ��`�84�97�,`� � 2 �, r� Z$�` �' 0.41 0.37 0.33 0.27 0.22 0.15 2.15
sub 67 � 5.38 0.00 97.00 ���9��00� `" 2 ,���� 2 0�`�� }�- 2.87 � 2.58 Z29 1.91 1.6 1.14 14.59
� N ,r. r Y � �
sub 7 8.23 1.31 81.68 u���81�4'1, ,,'' 2 � u..2.5 ., 3.95 3.52 3.09 2.52 2.07 1.45 20.94
TOTAL 171.89 63.68 78.5 77.4
80.7
EXISTING . 82.5
REDUCTION -2.2%
71.7 62.8 50.9 41.9 29.0 439.0
73.5 64.5 52.6 43.4 30.5 441.8
-2.4% -2.7% -3.1% -3.6% -4.9� -0.6%
City of Pickering
Downto�vn Stormwater Nlanag�rnent Strategy
TMIG Project 12150
PCSWMM Model Output
Alterantive 1
5 mm on-site retention, 100 Year Post to Pre, where Pre is based on current site cover
Maximum Flow Rate
Location Conduit 2 5 10 25 50 100 Hazel
Highway 401 34_1 9.86 1327 15.60 17.10 17.48 17.85 17.75
Bayly Street
Weir Fiow KC CJ44 HC 0.00 0.00 0.00 0.00 0.00 0.01 0.32
Culvert Flow KC CJ44 9.71 12.92 15.06 16.89 17.52 '17.97 17.87
Total Flow ADD 9.71 12.92 15.06 16.89 17.52 17.98 18.19
Downstrearn Bayly Street KC CJ43 12.41 16.65 19.61 22.16 23.77 25.14 24.82
Morden Lane
Weir Flow KC CJ37 HC 0.00 1.36 3.87 6,91 8.78 10,55 11.18
Culvert Flow KC CJ37 12.59 15.55 't6.30 16.62 16.76 16:81 16.99
Total ADD 12.59 16.91 20.16 23.53 25.54 27.36 28.17
Reytan Boulevard
Weir Flow KC CJ29 HC 0.04 0.36 4.42 7.39 9.27 9.80 13.10
Culvert Flow KC CJ29 12.25 14.14 14.81 15.03 15.12 15.39 15.29
Total ADD 12.29 14.50 19.23 2Z.42 24.39 25.19 28.40
Alyssum Street
Weir Flow KC CJ25 HC 0.17 2.63 8.07 12.37 15.03 15.11 21.25
Culvert Flow KC CJ25 11.58 12.15 12.17 12.10 12.00 11.91 11.72
Total ADD 11.75 14.78 20.24 24.47 27.03 27.02 32.98
Sandy Beach Road North Culvert
Weir Flow KC CJ20 HC 0.00 0.87 6.49 10.96 13.66 13.43 20.82
Culvert Flow KC CJ20 11.79 13.57 13.53 13.42 13.38 13.29 13.28
Total ADD 11.79 14.44 20.02 24.38 27.04 26.71 34.10
Confluence with East Tribut KC GA 16.18 21.62 28.07 35.32 40.54 43.55 48.45
Sandy Beach Road South Cuivert
Weir Flow KC CJ7 HC 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Culvert Flow KC CJ7 17.15 23.28 29.30 37.06 42.75 46.34 53.35
Total ADD 17.15 23.28 29:30 37.06 42.75 46.34 53.35
Outlet to Frenchman's Bay KC_CJ.4 16.19 20.69 24.82 29.72 32.94 35.35 61.46
��
�1
----- - --�- �___... ___.. ...._..- ---. -_-__ �----�.... ..__....� __� �! .,. ._--'.. � ,
.L_, ____._: �-._ �_._, __--- -.-'_`-
�J
-P
City of Pickering
Downtown Stormwater Management Strategy
TMIG Project 12150
PCSWMM Model Output
Alterantive 1
5 mm on-site retention, 100 Year Post to Pre, where Pre is based on current site cover
Maximum Hydraulic Grade Line (m)
Location Node 2 5 10 25 50 100 Hazel
Sandy Beach Road North Culvert - Downstream KC J19 76.75 77.03 77.26 77.39 77.46 77.45 77.62
Sandy Beach Road North Culvert - Upstream KC J20 77.14 77.54 77.71 77.78 77.82 77.�2 77.89
Alyssum Street Culvert - Downstream KC J24 77.22 77.60 77.80 77.93 78.00 78.00 78.15
Alyssum Street Culvert - Upstream KC J25 '� ��78�1`0'>� � �.,.;-.7�8�2�1,� T� ���,G78,�27 '`, � � �'78 30,..� ��,, r, �:
_ , �. t .r w�. r. F -
,'� � .a'� t „ -�- � ... .. Y „vF•v; .
Reytan Boulevard Culvert - Downstream KC J28 77.95 78.11 78.22 78.29 78.32 78.32 78.38
Reytan Boulevard Culvert - Upstream KC J29 �,� �78���72�;,�' ,��y�78�98 �'„ L 79�13�'`;�� �„79`�20 �� iF,��t 79�23��� ��r� 79 �24�`h� �„ ,�79 29 .':
Morden Lane Culvert - Downstream KC J36 78.91 79.17 79.60 79.64 79.64 79.70 79.75
Morden Lane Culvert - Upstream KC J37 79.99 ��' ' ` � '�� ` ° � �
� �.,
Bayly Street Culvert - Downstream KC J43 80.35 80.73 80.89 81.01 81.07 81.12 81.12
Bayly Street Culvert -Upstream KC J44 80.96 81.38 81.64 81.86 81.94 82.01 82.06
Highway 401 / CNR Culverts - Downstream KC J48 81.67 81.67 81.85 82.00 82.08 82.14 82.18
Highway 401 / CNR Culverts - Upstream 8 82.72 � 83:A0 83.97 84.38 84.54 ����84��65�'��; ��;�"�q�{65 =r�
TMIG � THE MUNICIPAL WFRASTRUCTURE GROUP LTD
Pickering City Centre
STORMWATER MANAGEMENTSTRATEGY
CIT.Y OF PICKERING
AppendlX A3
Post — to —Pre
Pre Runoff < 0.5
5 mm On-Site Retention
75
i
�
rn
Project: Pickering Downtown SWM
Project No: 12150
Date: 07-Jun-13
Suhcatchmpnts Paramptars fer Futura Cenditions in Downtown PickerinL
Scenario: 5 mm on-site.retention, post to, pre^`(based on pre at�50%„imqervious) "' PCSWMM output
100 Year 1hr 50 Year 1hr 25 Year 1hr 10 Year 1hr 5 Year 1hr AES 2 Year 1hr AES
AES (56.8mm) AES j51.4mm) AES (45.9mm) AES (38.5mm) (32.6mm) (23.8mm) Hazel Storm
Area to be � �" n � : �i " � �
� r Original � �Revised� ``
developed Original Revaed �€ r. ,� ��� �� � Runoff Runoff Runoff Runoff Runoff Runoff Runoff
Sub- Area � � � ,. Dstore Dstore
(ha) Imperv 4lmperv � � Volume Volume Volume Volume Volume Volume Volume
Catchmetn (ha) (targeted at (/) ,�� (y� ��� .�� �mperv ��Ulmperv ; �ML=10^6 L) (ML=10^6 L) (ML=10^6 L) (ML=10^6 L) (ML=10^6 L) (ML=10^6 L) (ML=10^6 L)
� �a �..� �.+; (mm) ,�(mm)��, :
50% mp.) �� � �� � � .
�� �'tiu,�r�w a�� ` �� �'� r � ��
sub 12 1.82 1.68 81.99 �'t'�52 40 2 �, 4`8 � 0.58 0.5 0.43 0.34 0.28 0.19 3.51
sub 13 2.98 2.98 81.99 t�50 04�� "' 2 ,r j,5�0��,� , 0.94 0.82 0.69 0.55 0.44 0.3 5.84
sub_17 1138 0.81 57.89 � 57*33 '� ; Z ''��'�'`�2 2` �`= 3.81 3.36 2.93 2.4 2.02 1.44 24J9
sub 18 11.10 4.02 45.84 � 4Z 35 k, . 2 3;^'1 ,; 3.9 3.37 2.85 2.19 1J1 1.13 23.47
_ �
sub 19 2.59 1.32 81.68 � 65 53 2 u 3:5, , 1.01 0.89 OJ7 0.62 0.51 036 5.81
t u „ a n�,F
sub_20 15.75 SJ3 97.00 70 94+ k� 2 3�7' �`ti 6.47 5J2 A.99 4.03 3.31 2.3 ��36.26
sub_21 10.20 3.44 97.00 ��S1S14 ���; 2 �t 3,�0 � 4.75 4.23 � 3.71 3.03 2.5 1J5 25.36
sub 23 2.31 0.00 62.59 � 62 59 �, � 2 � ��2 �04�w� : 0.99 0.87 OJ6 0.6 0.48 0.33 5.64
SUb 25 3.39 2.41 76.98 6�57 r79f >. 2 ��' 4"1�"" °r� 1.24 1.08 0.93 0.73 0.59 0.4 7.34
� ,! � r < ,� �R
sub 26 6.23 1.71 61.26 '� 45817' xki 2 rr 28��'� ' 2.43 2.12 1.82 1.43 1.15 OJS 13.93
a
sub 27 7.03 2.48 81.78 �, ��0 5.7���� 2 ��3,1��� �j 2.99 2.65 2.3 1.85 1.51 1.04 16J9
sub 28 5.3Z 5.32 81.68 ; 50 00� , x 2 '' �x5'�'0 �s�� � 1.67 1.45 1.24 0.97 OJ8 0.53 10.22
sub 3 1.08 0.29 86.79 �k"76 91�� �� 2 ;; �� �2��8������� 0.52 0.46 0.4 0.32 0.26 0.18 2.73
sub 30 7.42 0.77 81.68 ,�r78439'� ' 2 �Y� 2�,3�� ��� 3.44 3.06 2.68 2.18 1J9 1.25 18.54
sub 31 2.92 0.83 81.68 t'�72 67 `� , 2 �� �2{9�c� . 1.25 1.11 0.97 0.78 0.64 0.45 6.86
sub 32 2.97 0.00 81.68 S��81�68�`�� � 2 ��,��2 0 t�� �': 1.43 1.27 1.12 0.91 OJS 0.53 7.57
Sub 39 7,63 7.63 81.68 ��5001��� � 2 71 yrS,D ��� 2.52 2.18 1.85 1.44 1.14 0.76 15.94
S�� �1
sub 4 6.85 5.88 97.00 �� Sx6�68 � 2 �'�A 6�� � 2.07 1.86' 1.64 1,35 1.12 OJS 14.05
sub 40 11.47 11.47 81.68 `h50 01 4; , 2 x� 5;0 � 3.83 3.31 2.81 2.18 1.73 1.15 23.46
sub 48 7.28 0.00 20.62 20 62 ; 2 � `2ti0� 1.37 1.12 0.91 0.66 0.5 034 10.48
- , , t�
sub_5 12.54 0.00 86.79 ��867,9��'s� 2 '`2;0,�,,���� 6.39 SJ2 5.04 4.13 3.41 2.43 33.34
� sub 6 13.96 0.00 86J9 '�" °`86�79 �`� 2 � s�2€0���� 7.21 6.46 SJ 4.68 3.87 2.7 37.06
sub 61 1.77 0.30 86.58 � 86 37 '� ; 2 �;� a2'S �� � 3.28 2.88 2.48 1.97 1.58 1.07 18.34
sub_65 1.48 0.08 86.58. �?84�70 �,' 2 �,2'2��,':', 0.76 0.68 0.6 0.49 0.4 0.28 3.9
�� ,
sub 66 0.82 0.22 86.79 t£7�6 92 �}; 2 u"� 2 8 � �'� 0.39 0.35 0.3 0.25 0.2 0.14 2.07
sub 67 5.38 0.00 97.00 �``�9,� 00 ��' 2 �+`2'0` � 2.87 2.58 2.29 1.91 1.6 1.1A 14.59
sub 7 8.23 1.31 81.68 ���6�63,,,�;.��- 2 �,��2;5>��„�`, 3.78 3.36 2.94 2.38 1.96 1.36 20.41
TOTAL 171.89 63.68 78.5 66.3
71.9
EXISTING 82.5
REDUCTION -12.9%
63.5 55.2 44.4 36.2 25.1 408.3
73.5 64.5 52.6 43.4 30.5 441.8
-13.7% -14.5% -15.6% -16.6% -17.7% -7.6%
City of Pickering
Downtown Siormvvater Illlanage�oerat �trategy
TMIG Project 12150
PCSWMM Modei Output
Alterantive 2
5 mm on-site retention, 100 Year Post to Pre, where Pre is max 50% impervious
Maximum Flow Rate
Location Conduit 2 5 10 25 50 100 Hazel
Highway 401 34 1 9.48 12.63 14.87 16.85 17.35 17.67 17.56
Bayly Street
Weir Flow KC CJ44 HC 0.00 0.00 0.00 0.00 0.00 0.00 0.16
Culvert Flow KC CJ44 9.36 12.31 14.44 16.50 17.21 17.70 17.75
Total Flow ADD 9.36 12.31 14.44 16.50 17.21 17.70 17.91
Downstream Bayly Street KC CJ43 11.74 15.51 18.38 20.96 22.46 23.64 24.16
Morden Lane
Weir Fiow KC CJ37 HC 0.00 0.65 3.27 5.67 7.49 9.06 10.46
Culvert Flow KC_CJ37 11.97 15.10 16.01 16.53 16.66 16.78 16.97
Total ADD 11.97 15.74 19.28 22.19 24.15 25.84 27.43
Reytan Boulevard
Weir Flow ' KC CJ29 HC 0.01 0.29 2.88 6.28 8.04 9.74 12.42
Culvert Flow KC CJ29 11.65 13.68 14.65 14.94 15.05 15.11 15.28
Totai ADD � 11.66 13.97 17.53 21.22 23.09 24.85 27.70
Alyssum Street
Weir Flow KC CJ25 HC 0.05 1.99 5.63 10.88 13.39 15.85 20.35
Culvert Flow KC CJ25 11.28 12.08 12.10 12.03 11.95 11.87 11.70
Total ADD 11.32 14.07 17.73 22.91 25.34 27.72 32.04
Sandy Beach Road North Culvert
Weir Flow KC CJ20 HC 0.00 0.38 3.51 9.53 12.09 14.63 19.88
Cuivert Flow KC CJ20 11.39 . 13.49 13.49 13.41 13.38 13.34 . 13.28
Total ADD 11.39 13.87 16.99 22.94 25.47 27.98 33.17
Confluence with East Tribu KC CA 15.88 21.38 26.54 33.50 38.96 44.72 47.54
Sandy Beach Road South Cuivert
Weir Flow KC CJ7 HC 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Culvert Flow KC CJ7 16.89 23.09 28.00 35.62 41.42 47.34 52.48
Total ADD 16.89 23.09 28.00 35.62 41.42 47.34 52.48
Outlet to Frenchman's Bay KC_CJ.4 15.93 20.48 23.97 29.13 32.39 35.52 60.90
77
J
Oa
--.,_ __,_. __--- ----, --- _��_.
City of Pickering
Downtown Stormwater Management Strategy
TMIG Project 12150
PCSWMM Model Output
Alterantive 2
5 mm on-site retention, 100 Year Post to Pre, where Pre is max 50% impervious
Maximum Hydraulic Grade Line (m)
Location Node 2 5 10 25 50 100 Hazel
Sandy Beach Road North Culvert - Downstream KC J19 76.70 77.00 77.15 77.35 77.42 77.48 77.61
Sandy Beach Road North Culvert - Upstream KC J20 77.08 77.50 77.64 77.76 77.80 77.84 77.88
Alyssum Street Cuivert - Downstream KC J24 77.16 77.56 77.71 77.89 77.95 78:02 78.13
Alyssum Street Culvert - Upstream KC J25 77 88 4 78z Q8 .;78� 17�, ��,`78 25 ��'� r78 2'8��s4z ��,��7g��3'1a 'A �" � L78.35: •:
Reytan Boulevard Culvert - Downstream KC_J28 77.91 78.09 78.18 78.27 78.30 78.33 78.37
Reytan Boulevard Culvert - Upstream KC J29 �, 78:k62� r�, s� 78 92�..�, �.°79f08�r;`� �f� 79 17 ,,� ;� 79:21� }��' �`'���79�24r.;fi n� ��,79.2&` ,
Morden Lane Culvert - Downstream KC J36 78.87 79.11 79.53 79.63 79.64 79.64 79.73
Morden Lane Culvert - Upstream KC J37 79 91 ;5 � 80,N35 � k' 80 50*��� b,�.80�;59 �ry� ; s, 80f',63�x�;�� ����80�66�.; � f�c,`80s68° ':
Bayly Street Cuivert - Downstream KC J43 80.29 80.65 80.84 80.96 81.02 81.07 81.10
Bayly Street Culvert =Upstream , KC J44 80.91 81.30 81.55 81.80 81.90 81.96 82.04
Nighway 401 / CNR Culverts - Downstream KC J48 81.67 81.67 81.78 81.96 82.04 82.10 82.16
Highway 401 / CNR Culverts - Upstream 8 82:65 83.27 83.80 84.30 84.47 84.59 84.59
f,; ,, �,,���.��e�� filood damages incurred
TMIG � THE MUNICIPAL INFRASTRUCTURE GROUP LTD
Pickering City Centre
STORMWATER MANAGEMENT STRATEGY
CITY OF PICKERING
Appendix A4
Post — to —Pre
Pre Runoff < 0.5
10 mm On-Site Retention
�
8
i..
Project: Pickering Downtown SWM
Project No: 12150
Date: 07-Jun-13
Subcatchments Parameters for Future Conditions in Downtown Pickering
Scenario: '10 mm on-site refention;'post-to-pre @ased;on pre at.50%"impervious) ':' PCSWMM output
100 Year 1hr . 50 Year 1hr 25 Year 1hr 10 Year 1hr 5 Year 1hr AES 2 Year 1hr AES
AES (56.8mm) AES (51.4mm) AES (45.9mm) AES (38.Smm) (32.6mm) (23.8mm) Hazel Storm
Area to be � ' '�� �� `
� �� ,{ Origina) ',�Revised :
developed Original � Rev�sed��°� �,�s�� q�`�� �% Runoff Runoff Runoff Runoff Runoff Runoff Runoff
Sub- Area ��$ Dstore � 4��Dstore �
Catchmetn (ha) (ha) . Imperv � Imperv af Im erv Im �erv ; Volume Volume Volume Volume Volume Volume Volume
(targeted at (%) "(%) yF� p � P }: (ML=10^6 L) (ML=10^6 L) (ML=10^6 L) (Mt=10^6 L) (ML=10^6 L) (ML=10^6 L) (ML=10^6 L)
°� p 1 � ����, � � ,w �mm) �, (min),�„���;
50/im ���� � ����„ � w
sub 12 1.82 1.68 81.99 4, 52,40���'��% 2 f���,��9 4��> 0.55 0.47 0.4 0.31 0.24 0.16 3.48
sub 13 2.98 2.98 81.99 `�SOt04���k �: 2 %a �'�10�0� �n�� 0.88 0.76 0.64 0.49 0.38 0.24 ' S.79
x �k. ,�`�+' 7''�"
�
sub 17 11.38 0.81 � 57.89 s���5�3��`;' � 2 ��� 2`��6„ ��'`�� 3J9 334 2.91 2.38 2 1.42 24.77
sub 18 11.10 4.02 45.84 �{�4=7��35��' f 2 ���+� 4#9 ��� �h' 3.83 3.3 2.78 2.11 1.64 1.06 23.4
�
g " ` s t� 'a �� 'i
sub 19 2.59 1.32 81.68 J65�53�r��,� 2 ;�,��g�6�1��^ �; 0.98 0.86 OJ4 0.59 0.48 0.32 5.78
sub 20 15.75 � 8.73 97.00 � 7,0?94�'�''�"j 2 ��f"�6�,42P���� 6.24 � 5.5 • 4J6 3.81 3.09 2.08 � 36A3
sub 21 10.20 3.44 97.00 k� 81t14{ 2 ,�` 4�7; � 4.65 4.13 3.61 2.92 239 1.64 25.25
sub 23 2.31 0.00 62.59 � 6��59��,�t'� 2 � z'2 �0 ``� � 0.99 0.87 0.76 0.6 0.48 0.33 � 5.64 �
sub 25 3.39 2.41 76.98 �,� 57 794 x�4 2 �T��q �7;7�, k ff; 1.19 1.03 0.87 0.68 � 0.54 0.35 7.29
5Ub 26 6.23 1J1 61.26 " r Sg 17 "` f 2 " n� � 4�2���� " 2.39 � 2.08 1.78 1.39 1.11 0.75 13.89
ER �i b i ¢ , ��t�a`��'t{. ; �# , �'.
sub 27 7.03 2.48 81.78 7Q 57� ' v 2 � 4°8 ,; 2.93 2.58 2.24 1J9 1.45 0.98 16J3
flA,
sub 28 5.32 5.32 81.68 "� �50'00� 2 ��k��10�0� 1.57 1.35 1.14 0.87 0.68 0.43 10.12
r �
sub 3 1.08 0.29 86.79� 7691��� ;� 2 yy+�TF��,1w� ,;, 0.51 0.45 0.39 0.32 0.26 0.17 2J2
sub 30 7.42 OJ7 81.68 78 39 �`+ 2 �,;��`�2�8�' 3.42 3.04 2.66 2.16 1.77 1.23 18.52
�
sub 31 2.92 0.83 81.68 t ti7Z`67�'" ' 2 ,�� y4�3� � 1.23 1.09 0.94 0.76 0.62 0.43 6.84
� sub 32 2.97 0.00 81.68 6��8�1q6$�x ; 2 �,�. �s�'f 2�Or��t ��!� 1.43 1.27 1.12 0.91 OJS � 0.53 7.57
r ,t
sub 39 7.63 7.63 81.68 t�t50 01� 2 ��r10 0��'� - 2.38 2.04 1J1 1.3 1 0.62 15J9
_ �
sub 4 6.85 5.88 97.00 r 5� 68� �' � `� �s 8€9� 1.95 1.73 1.52 1.23 1 0.66 13.93
sub_40 11.47 11.47 8�1.68 t 50 0�� J��! 2 � ��� a1�0 0� � F' 3.62 3.1 2.59 1.96 1.51 0.93 23.25
r a �,� � rNS .�
sub_48 7.28 0_00 � 20.62 2� 62 �� 2 ��� 2 D� *`� 137 1.12 0.91 0.66 0.5 0�34 10.48
sub 5 12.54 0.00 86.79 ` p8�6 7�s �� a 2 � Y� �2 0��� 6.39 5.72 5.04 4.13 3.41 2.43 3334
sub 6 13.96 0.00 86J9 f 86 7�9s �'� 2 ��,� �2W0�'s � r� 7.21 6.46 5J 4.68 3.87 2.7 37.06
sub 61 1.77 0.30 86.58 � 380�37� 2 ��� 3:4 �; 3.24 2.84 2.44 1.92 1.54 1.02 18.29
sub 65 1.48 0.08 86.58 ��<�8�4�70� r� 2 ���� Z�4� �; „� OJ5 0.67 0.59 . 0.�9 0.4 0.28 3.9
sub 66 0.82 0.22 86.79 ��t 6�92,� . 2 „�k4"1� t 0.39 0.34 0.3 0.24 0.19 0.13 2.07
�
sub_67 5.38 0.00 97.00 '`=;�9700�' ,; 2 u t20 �, 2.87 2.58 2.29 1.91 1.6 1.14 14.59
�
sub 7 8.23 131 81.68 �,„75 63�, ��`:'� 2 �'3:3', 3.75 3.32 2.9 2.35 1.92 1.33 20.38
TOTAL 171.89 63.68 78.5 66.3
70.5
EXISTING 82.5
REDUCTION -14.6%
62.0 53.7 43:0 34.8 23.7 406.9
73.5 64.5 52.6 43.4 30.5 441.8
-15.6% -16J% ' -18.3% -19.8% -22.3% -7.9%
Cify of Pickering
o�vntov�rn tor ater ana e ent trategy
TMIG Project 12150
PCSWMM Model Output
Alterantive 3
10 mm on•site retention, 100 Year Post to Pre, where Pre is max 50% impervious
Maximum Flow Rate
Location Conduit 2 5 10 25 50 100 Hazel
Highway 401 34 1 9.16 12.28 14.61 16.75 17.31 17.62 17.56
Bayly Street
Weir Flow KC CJ44 HC 0.00 0.00 0.00 0.00 0.00 0.00 0.16
Culvert Flow KC CJ44 9.32 12.00 14.17 16.37 17.13 17.64 17.75
Total Flow ADD 9.32 12.00 14.17 16.37 17.13 17.64 17.91
Downstream Bayly Street KC CJ43 11.34 15.10 17.87 20.77 2224 23.49 24.16
Morden Lane
Weir Fiow KC CJ37 HC 0.00 0.42 2.79 5.53 7.23 8.84 10.46
Culvert Flow KC CJ37 11.56 14.89 15.99 16.51 16.65 16.77 16.96
Total ADD 11.56 15.31 18.78 22.04 23.88 25.61 27.42
Reytan Boulevard
Weir Flow KC CJ29 HC 0.00 0.27 2.74 6.04 7.80 9.51 12.42
Culvert Flow KC CJ29 11.09 13.54 14.62 14.93 15.04 15.10 15.28
Total � ADD 11.09 13.81 17.36 20.97 22.84 24.61 27.70
Alyssum Street
Weir Flow KC CJ25 HC 0.01 1.69 4.72 10.50 13.06 15.51 20.35
Culvert Flow KC CJ25 11.00 12.05 12.07 12.01 11.94 11.86 11.70
Total ADD 11.01 13.74 16.79 22.51 24.99 27.37 32.05
Sandy Beach Road North Culvert
Weir Flow KC CJ20 HC 0.00 020 2.73 9.14 11.75 14.30 19.88
Culvert Flow KC CJ20 11.10 13.41 13.48 13.42 13.38 13.34 13.28
Total ADD 11.10 13.61 16.21 22.56 25.13 27.64 33.17
Confluence with East Tribut KC CA 15.60 21.18 25.40 33.07 38.37 44.52 47.54
Sandy Beach Road South Culvert
Weir Flow KC CJ7 HC 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Culvert Flow KC CJ7 16.62 22.92 27.27 35.06 40.89 46.97 52.48
Total ADD 16.62 22.92 27.27 35.06 40.89 46.97 52.48
Outlet to Frenchman's Bay KC_CJ.4 15.70 20.33 23.69 28.94 32.21 35.39 60.90
�+�
�
�_-_- __ _._ _�. --_-- ___ . .� __. i__,
City of Pickering
Downtown Stormwater Management Strategy
TMIG Project 12150
PCSWMM Model Output
Alterantive 3 -
10 mm on-site retention, 100 Year Post to Pre, where Pre is max 50% impervious
Maximum Hydraulic Grade Line (m)
Location Node 2 5 10 25 50 100 Hazel
Sandy Beach Road North Culvert - Downstream KC_J19 76.66 76.98 77.12 77.34 77.41 77.48 77.61
Sandy Beach Road North Culvert - Upstream KC J20 77.04 77.48 77.61 77.76 77.80 77.83 77.88
Alyssum Street Culvert - Downstream KC J24 77.12 77.54 77.69 77.88 77.95 78.01 78.13
Alyssum Street Culver�- Upstream � KC J25 77,�84�.,°,,F` ;78�0� '�r, 78�15',,, � 7,.8;�25 d�,�x, 78�28rh� �����78�31;;"� �,, �78.35 ',�:
Reytan Boulevard Culvert - Downstream KC J28 77.86 78.08 78.16 78.26 . 78.29 78.32 78.37
Reytan Boulevard Culvert - Upstream KC J29 � ;478F52� �� �����78�9�1�£ 4� � 79�075 �}� r }79�17� � �;s t��,7�9�20�"����� ,���;79"23�;� ��k�`�79 28,,,, :
Morden Lane Culvert - Downstream KC J36 78.84 79.09 79.46 79.63 79.64 79.64 79.74
Morden Lane Culvert - Upstream KC J37 ��� �79�'85��� ����`80�33"� , ;A�z�gO g49��,�� �f �8Q''59 r�� �� ;k`80�62�7��� �����5�0`�66�,` 1� ��r' 80�68 ;"
Bayly Street Culvert - Downstream KC J43 80.25 80.62 80.82 80.96 81.02 81.06 81.10
Bayly Street Culvert -Upstream KC_:J44 80.87 81.26 81.52 81.79 81.88 81.95 82.04
Highway 401 / CNR Cuiverts - Downstream KC J48 81.67 81.67 81.76 81.95 82.03 82.09 82.16
Highway 401 / CNR Culverts - Upstream 8 82.59 83.20 83.73 84.27 84.45 84.58 84.59
Pickering City Centre
STORMWATER MANAGEMENT STRATEGY
CITY OF PICKERING
Appendix A5
Post — to —Pre
Pre Runoff < 0.5
95 mm On-Site Retention
TMIG � THE R4UNICIPAL INFRASTRUCTURE GROUP LTD
83
-- - --- - --- ---- - - _____ - �. ' �_ � _L_.
00
-�.,, �
Project: Picicering Downtown SWM
Project No: 12150
Date: 07-JUn-13 ,
Subcatchments Parameters for Future Conditions in Downtown Pickerins
ScenaPio: 15 mm on-site,retent�on; post to-pre;`(based'on'pre at 50%,impeivious) ,. ' PCSWMM output
• 100 Year 1hr 50 Year 1hr 25 Year 1hr 10 Year 1hr 5 Year 1hr AES 2 Year 1hr AES
AES (56.8mm) AES (51.4mm) AES (45.9mm) AES (38.5mm) (32.6mm) (23.Smm) Hazel Storm
Area to be � �+��� `�`� , ; � < � ��{�� °
developed Original ���Rev�sed � Original �Rev�e�r � Runoff Runoff Runoff . Runoff Runoff Runoff Runoff
Sub- Area � �k � ,$ � Dstore �`�Dstore �
(ha) Imperv �zk�mperv � � � : Volume Volume Volume Volume Volume Volume Volume
Catchmetn (ha) (targeted at (/) �" �(%�'� ^', �mpe� ; �mPeN� � ML=10^6 L ML=10^6 L M1=10^6 L ^ ) (ML=10^6 L ^ ^
� r � � ar ;� (mm) ��"(mmy� `� ( � � � � ) (ML=10 6 L ) (ML=10 6 L) (ML=10 6 L)
50%imp.) ru� �i,�'�z � � �� �ct :
� s ,'�,�r u� r ,..t�n,,.t,=<,E
sub 12 1.82 1.68 81.99 �' S2�40 �"" Z �' 14 0 j�� << 0.51 0.44 0.37 0.28 0.21 0.12 3.45
� , t�
sub 13 2.98 2.98 81.99 �� 50 04� Y: 2 ��`` 15 0� �� 0.83 OJ � 0.58 OA3 0.33 0.18 5.73
sub_17 11.38 0.81 57.89 ' S7�33 �r,; ��� �
' 2 �' ����9���r 3.78 3.33 2.9 2.37 1.98 1.41 24J6
sub 18 11.10 4�.02 45.84 � 47�35 M1�`, 2 ,� � 6��7� fi��� ; 3,76 3.23 2.71 2.04 1.57 0.99 23.33
sub 19 2.59 1.32 81,68 >"�65'�S3 K 2 "� 8s6;4� 0.95 0.83 0.71 0.56 0.45 0.29 5J5
f , C-
sub 20 15J5 8.73 97.00 � 70a94 �` 2� e�°9r2-' �:' 6.01 � 5.26 4.52 3.57 2.85 1.84 35J9
`.3 i '
sub 21 10.20 3.44 97.00 `,8�414�, ��, 2 �6 4�„� 4.54 4.02 3.5 2.81 2.29 1.54 25.14
sub 23 2.31 0.00 62.59 x 62 59 i 2 , f 2 0;'��„� - 0.99 0.87 OJ6 0.6 0.48� 0.33 5.64
sub�25 3.39 2.41 76.98 � 357�79 �J 2 11;2 �+�' 1.14 0.98 0.82 0.63 0.4.9 0.3 7.24
SUb_26 6,23 1.71 6�1.26 t� 58r`17� r� i 2 r �
`'� ``' � 5 6�"''. z+ 2.35 2.05 1.74 1.36 1.07 0.71 13.85
sub 27 7.03 2.48 81J8 70 57 �` 2 �`fi 6 6�� 2.86 2.52 2.17 1J2 1.38 0.91 16.66
sub 28 5.32 532 81.68 � 50 00 2 ` 15 0 E ° 1.47 1.25 1.04 0.77 0.58 0.33 10.02
sub 3 1.08 0.29 86.79 � f�7fi,91 °. 2 S�Sr �' 0.5 0.44 0.38 0.31 0.25 0.16 2J2
sub 30 7.42 0.77 81.68 �� 78 89 2 , 3�'3'� �'! 3.4 3.02 2.64 2.14 1J5 1.21 18.49
s
sub 31 2.92 0.83 81.68 72 67 2 � 5`'7i 1.21 1.06 0.92 0.74 0.6 0.41 6.82
sub_32 2.97 0.00 81.68 �`�81`68 `�£': 2 � 20�"� " 1.43 1.27 1.12 0.91 0.75 0.53 7.57
sub 39 7.63 7.63 81.68 �' 50 01 2 � 15 0;' 2.24 1.9 1.57 1.15 0.86 0.47 15.65
t ; s �I n
sub_4 6.85 5.88 97.00 �� 56 68 ;'; 2 ,''13'2 � a' 1.82 1.61 1.39 1.1 0.87 0.53 13.8
�
sub_40 11.47 11.47 81.68 ��50 0� 2 k� 15 Oz� ' 3.4 2.88 2.38 1.75 1.29 OJ2 23.03
sub 48 7.28 ' O.OQ � 20.62 � 20:52' g' 2 � ,,�2�0 � t � 1.37 1.12 0.91 0.66 0.5 0,34 10.A8
�
�
sub_5 12.54 0.00 86.79 ��t�86`�79 ��t! 2 ; 2*Q� � rt 6.39 SJ2 5.04 4.13 3.41 2.43 33.34
sub 6 13.96 0.00 86J9 86�79�� '`. 2 7`�2�Q 7.21 6.46 SJ 4.68 3.87 2.7 37.06
� � '
sub 61 1.77 0.30 86.58 i 80�37 � 2 �� �4�2� %� � 3.19 2J9 2.3�9 1.87 1.49 . � 0.97 18.25
sub_65 1.48 0.08 86.58 " 84 �0 �� 2 2�7{' � r; OJS 0.67 0.59 0.48 0.4 0.27 3.9
sub_66 0.82 0.22 86J9 ' 76 92 �;`�, 2 ,5 5; 1`; 0.38 0.34 0.29 0.23 0,19 0.12 2.06
sub 67 538 0.00 97.00 � 97"�00 `'` 2 i' 2 0 �' Z.S7 2.58 2.29 1.91 1.6 . 1.14 14.59
- � ���: � �i �� � ;
sub_7 8.23 1.31 81.68 r 7,6..6�3� ,�;_ 2 ,,:9�1�' ., .;��� 3.71 � 3.29 � 2.86 2.31 1.88 1.29 20.34
TOTAL 171.59 63.68 78.5 66.3
69.1
EXISTING 82.5
REDUCTION -16.3%
60.6
73.5
-17.5%
52.3
64.5
-18.9%
41.5
52.6
-21.OY
33.4
43.4
-23.1%
22.2
30.5
-27.1%
405.5
441.8
-8.2%
Ciiy of Pickering
Downtown Stor�ro�vater Managernent S$rategy
TMIG Project 12150
PC$11VMM Model Output
�4lterantive 4
15 mm on-site retention, 100 Year Post to Pre, where Pre is max 50% impervious
.
Location Conduit 2 5 10 25 50 100 Hazel
Highway 401 34 1 8.88 11.99 14.33 16.64 17.25 17.58 17.56
Bayly Street
Weir Flow KC CJ44 HC 0.00 0.00 0.00 0.00 0.00 - 0.00 0.16
Culvert Flow KC CJ44 9.32 11.70 13.88 16.21 17.04 17.58 17.75
Total Flow ADD � 9.32 11.70 13.88 16.21 17.04 1 Z.58 17.91
Downstrearn Bayly Street KC CJ43 10.82 14.72 17.50 20.56 22.06 23.33 24.16
Morden Lane
Weir Flow KC CJ37 HC 0.00 0.21 1.99 5.53 7.04 8.62 10.45
Culvert Flow KC CJ37 11.10 14.65 15.93 16.47 16.64 16.75 16.94
Total ADD 11.10 14.86 17.92 22.01 23.68 25.36 27.40
Reytan Boulevard
Weir Flow KC CJ29 HC 0.00 0.23 2.62 5.77 7.58 9.28 12.42
Culvert Flow KC CJ29 10.73 13.36 14.46 14.91 15.03 15.09 15.28
Total ADD 10.73 13.60 17.08 20.68 22.60 24.38 27.70
Alyssum Street
Weir Flow KC CJ25 HC 0.00 1.40 4.31 10.07 12.75 15.18 20.34
Culvert Flow KC_CJ25 10.67 12.01 12.05 11.99 11.92 11.84 11.70
Total ADD 10.67 13.41 16.35 22.06 24.67 27.02 32.04
Sandy Beach Road North Culvert
Weir Flow KC CJ20 HC 0.00 0.07 2.32 8.73 11.45 13.97 19.88
Culvert Flow KC CJ20 10.76 13.27 13.49 13.42 13.38 13.35 13.28
Total ADD 10.76 13.34 15.80 22.15 24.83 27.32 33.16
Confluence with East Tribut KC CA 15.28 21.02 24.69 32.58 37.81 44.01 47.54
Sandy Beach Road South Culvert
Weir Fiow KC CJ7 HC 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Culvert Flow KC CJ7 16.31 22.77 27.06 34.48 40.41 46.59 52.47
Total ADD 16.31 22.77 27.06 34.48 40.41 46.59 52.47
Outlet to Frenchman's Bay KC_CJ.4 15.45 2Q.20 23.45 28.72 32.06 35.25 60.90
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__ -- __-- ---.- --- _. ____:__ _�_�.__w �_ .__--- __'_,- _.. _.� __ __.�.� _��. �_. _�
C�ty of P�ckermg
Downtown Stormwater Management Strategy
TMIG Project 12150
PCSWMM Model Output
Alterantive 4
15 mm on-site retention, 100 Year Post.to Pre; where Pre is max 50% impervious
Maximum Hydraulic Grade Line (m)
Location Node 2 5 10 25 50 100 Hazel
Sandy Beach Road North Culvert - Downstream KC J19 �76.62 76.96 77,11 77.33 77.40 77.47 77.61
Sandy Beach Road North Cuivert - Upstream KC J20 77.00 77.45 77.60 77.75 . 77.79 77.83 77.88
Atyssum Street Culvert - Downstream KC J24 77.08 77.51 77.67 77.86 77.94 78.00 78.13
Alyssum Street Culvert - Upstream � KG J25 77 79 '�� 78�Q6 � , ,7,8 14 ��x . ;���,,?8�24�n�� ,`°� � " ���o� ��, 78, 30 ,,a�� `, `
Reytan Boulevard Culvert - Downstream KC J28 77:81 78.07 78.15 78.25 78.29 78.32 78.37
Reytan� Boulevard Culvert - Upstream � KC_J29 78.47 � � �' � ' ���� �� ,79; 16��'��' , ' � ' � �' �� ; 79 23 ��� 79 28 ,��'.
Morden Lane Culvert - Downstream KC J36 78.81 79.07 79.28 79.63 79.64 79.64 79.73
Morden Lane Culvert - Upstream KC J37 79 79 �� �8�0'�29�� ' �"� "� ° "� ``" '` � � ��`
7s �
Bayly Street Culvert - Downstream KC J43 80.22 80.58 80.80 80.95 81.01 81.06 81.10
Bayly Street Culvert -Upstream KC J44 80.82 81.22 � 81.49 81.77 81.87 81.94 82.04
Highway 401 / CNR Culverts - Dovunstream KC J48 81.67 8.1.67 81.74 81.94 82.02 82.08 82.16
Highway 401 / CNR Culverts - Upstream 8 82.53 83.13 83.65 84.24 84.43 84.56 84.59
Pickering Gity Centee
STORf�iWATER MANAGEMENT STRATEGY
CITY OF PICKERING
� Appendix A6
� LIDs in Road RO Ws
TMIG � THE MUNICIPAL 1NFRASTRUCTURE GROUP LTD
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Project: Pickering Downtown SWM
Project No: 12150
Date: 07-14n-13
Subcatchments Parameters for Future Conditions in Downtown Pickerin�
Scenario: Applicatiomof LIDs to �100%'of.Road ROWs?in Downtown Area `.,� ' PCSWMM output
100 Year 1hr 50 Year 1hr 25 Year 1hr 10 Year 1hr 5 Year 1hr AES 2 Year 1hr AES
AES (56.8mm) AE5 (51.4mm) AES (45.9mm) AES (38.5mm) (32.6mm) (23.8mm) Hazel Storm
,
ROW Area Original �} ReV�sed,
Originai Revised ;=x��?� � Runoff Runoff Runoff Runoff Runoff Runoff Runoff
Sub- Area (ha) Dstore � Dstore . -
Catchmetn (ha) (25 mm �mperv imperv �mperv � jmpeN „ Volume Volume Volume Volume Volume Volume Volume
(%) (%) � 's .. (ML=10^6 L) (ML=10^6 L) (ML=10^6 L) (ML=10^6 L) (ML=10^6 L) (ML=10^6 L) (ML=10^6 L)
storage) (mm) � ���(rnm�
�;,
sub_12 1.82 0.63. 81.99 2 '� d`0 0 r 0.77 0.68 0.59 0.46 0.37 0.23 4.43
sub_13 2.98 1.13 81.99 2� 10 79 ,�� 1.27 1.12 0.96 OJ6 0.6 0.38 7.36
sub 17 11.38 0.00 57.89 Z 2 0 tY 3.86 �3.41 2.97 2.44 2.04 1.46 24.9
��.
sub_18 11.10 2.90 45.84 2 ',,8 0�, 3.65 3.12 2.6 1.94 1.48 0.91 23.04
sub_19 2.59 0.86 81.68 2 9 7� 1.11 0.98 0.84 0.67 0.53 0.34 639
sub_20 15.75 1.03 97.00 � 2 ;3"'S ,`; 8.28 7.44 � 6.57 5.41 4.49 �3.14 42.34
sub_21 10.20 0.71 97.00 , 2 3 6, '. 5.37 4.82 4.26 3.51 2.91 2.03 27.48
sub 23 2.31 0.22 62.59 2 �� '4'2 0.97 0.85 OJ3 0.58 0.46 0.3 5.62
sub 25 3.39 0.60 76.98 2 � `60�r �; 1.49 1.32 1.14 0.92 0.74 0.5 8.31
sub_26 6.23 0.00 61.26 2 �2 D' , 2.53 2.22 1.92 1.52 1,23 0.85 14.23
sub 27 7.03 0.89 81.78 2 f � 4 9, 3.26 2.89 2.52 2.04 1.66 1.13 17.8
sub_28 5.32 1.70 81.68 2 } 9 4 • 2.29 2.02 1.74 138 1.1 0.7 13.08
sub 3 1.08 0.00 86J9 2 ��2}0� � 0.56 0.5 0.44 036 0.3 0.21 2.87
`s
sub_30 7.42 0.42 81.68 2 3"3�3 , 3.5 3.11 2.73 2.22 1.82 1.26 18.81
,. ,.
sub 31 2.92 0.23 81.68 2 { �3�8 1.36 1.21 1.06 0.86 0.7 0.49 7.27
sub_32 2.97 0.04 81.68 2 �,2 3 w� '��; 1.42 1.27 1.11 0.91 OJ5 0.52 7.56
sub_39 7.63 1.53 81.68 2 6 6` ` 3.48 3.08 2.68 2.15 1J4 1.15 19.4
sub 4 6.85 1.45 97.00 2 '��6�9 �.^' � 3.41 3.04 2.68 2.18 1.79 1.21 18.33
_ } �;V,-
sub_40 11.47 1.60 81.68 2 ' �5 Z 536 4.76 4.15 3.35 2.73 1.85 29.03
sub 48 7.28 0.94 20.62 2 h%570� � E� 1.33 1.09 0.87 0.63 0.47 0.3 10.45
sub_5 12.54 0.00 86J9 2 3�,20�� 6.39 5J2 5.04 4.13 3.41 2.43 3334
;� , '
sub_6 13.96 0.00 86J9 2 � a�j2i0��3 7.21 6.46 SJ 4.68 3.87 2.7 37.06
sub_61 1.77 0.00 86.58 2 �;2 0 3.43 3.03 2.63 2.1 1.71 1.17 18.81
sub 65 1.48 0.00 86.58 2 �2 0 f 0.77 0.69 0.61 0.5 0.41 0.29 3.93
sub_66 0.82 0.00 86J9 2 -� 0� 0.42 0.38 0.33 0.27 0.23 0.16 2.18
sub_67 5.38 � 0.60 97.00 2 E ,4 6 2J6 2.48 2.19 1.8 1.5 1.04 14.49
sub 7 8.23 2.11 81.68 2 �'. �7 9, _'� ;� 3.69 3.26 2.82 2.25 � 1.81 1.18 20J
TOTAL 171.89 19.60 78.5 0.0
EXISTING
REDUCTION
79.9
82.5
3:1%
71.0
73.5
-3.5%
61.9
b4.5
-4.096
50.0
52.6
-4.9%
40.9
43.4
-5.9%
27.9
30.5
-8.5%
439.2
441.8
-0.6%
City of Pickering
Dovvntown Storm�vater IVlanagernent Strategy
TMIG Project 12150
..- � .;
LIDs in City Streets
25 mm retention of runoff volume from road ROW
Maximum Flow Rate
Location Conduit 2 5 10 25 50 100 Hazel
Highway 401 34 1 9.43 12.80 15.17 17.00 17.40 17.77 17.75
Bayly Street ..
Weir Flow KC CJ44 HC 0.00 0.00 0.00 0.00 0.00 0.00 0.32
Culvert Flow KC CJ44 9.32 12.48 14.71 16.76 17.43 17.89 17.87
Total Flow ADD 9.32 12.48 14.71 16.76 17.43 17.90 18.19
Downstream Bayly Street KC_CJ43 11.98 16.27 19.30 22.03 23.74 25.17 24.86
Morden Lane
Weir Flow KC CJ37 HC 0.00 1.08 3.71 6.70 8.69 10.52 11.23
Culvert Flow KC CJ37 12.19 15.39 16.20 16.61 16.76 16.80 16.99
Total ADD 12.19 16.47 19.92 23.31 25.45 27.32 28.22
Reytan Boulevard
Weir Flow KC CJ29 HC 0.01 0.33 4.07 7.28 9.21 9.77 13.15
Culvert Flow KC CJ29 11.84 13.95 14.78 15.02 15.12 . 15.39 15.30
Total ADD 11.85 14.29 18.84 22.30 24.32 25.16 28.45
Alyssum Street
Weir Flow KC CJ25 HC 0.08 2.38 7.52 12.21 14.93 15.05 21.32
Culvert Flow KC CJ25 11.40 12.13 12.16 12.09 11.98 11.90 11.72
Total ADD 11.47 � 14.51 19.68 24.30 26.91 26.95 33.04
Sandy Beach Road North Culvert
Weir Flow KC CJ20 HC 0.00 0.66 5.99 10.80 13.55 13.34 20.89
Culvert Flow KC CJ20 11.52 13.56 13.52 13.42 13.38 13.29 13.28
Total ADD 11.52 14.22 19.50 2422 26.93 26.63 34.17
Conffuence with East Tribut KC CA 15.95 21.47 27.60 34.93 40:29 43.64 48.52
Sandy Beach Road South Culvert
Weir Flow KC CJ7 HC 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Culvert Flow KC CJ7 16.94 23.15 28.87 36.72 42.52 46.27 53.42
Total ADD 16.94 23.15 28.87 36.72 42.52 46.27 53.42
Outlet to Frenchman's Bay KC_CJ.4 16.00 20.57 24.58 29.61 32.87 35.31 61.49
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City of Pickering
Downtown Stormwater Management Strategy
TMIG Project 12150
PCSWMM Modei Output
LIDs in City Streets
25 mm retention of runoff volume from road ROW
Maximum Hydraulic Grade Line (m)
Location Node 2 5 10 25 50 100 Hazel
Sandy Beach Road North Culvert - Downstream KC J19 76.71 77.02 77.24 77.38 77.45 77:45 77.63
Sandy Beach Road North Culvert - Upstream KC J20 77.10 77.53 77.70 77.78 77.82 77.82 77.89
Alyssum Street Culvert - Downstream KC :124 77.18 77.59 77.79 77.92 77.99 78.00 78.15
KC_J25 77.90 " 78:09� ,3 `, ; ;78 20�A„� � �h,.78�2�7" ` 78�'30'��; � `���78 `30 ;? , � ,. 7$:35 . '
Reytan Boulevard Culvert - Downstream KC J28 . 77.92 78.10 78.21 78.28 78.32 78.32 78.38
KC J29 � ,78:f65 > ;�, 78,:96m,,, 79��12 f�� ' .�.79�19�,�� � 7923� � � �. ��79 24 : 7.9:=29 . ?
Morden Lane Culvert - Downstream KC J36 78.89 79.15 79.59 79.64 79.64 79.70 79.74
C_J37 , 79.94 " �80 40 ,,. ,,, 80 53 ��� „�� `��80`6t1 �,� � ; 8b�65�.�� ��;�80�68 r; ��$80 70 `:
Bayly Street Culvert - Downstream KC J43 80.31 80.70 80.88 81.00 81.07 81.12 81.12
Bayly Street Culvert -Upstream KC J44 80.91 81.33 81.59 81.85 81.94 ���82 01';�° �� `,�82:06'` ����
Highway 401 / CNR Culverts - Downstream KC_J48 81.67 81.67 81.82 81.99 82.07 82.13 82.18
Highway 401 / CNR Culverts - Upstream 8 82.64 83.30 83.87 84.35 84.51 84.63 84.64
�
Pickering City Centre
STORMWATER MANAGEMENTSTRATEGY
CITY OF PICKERING
� � � ' • ; i-
Pickering Town Centre
Fload Storage Assessment
TMIG � THE MUNICIPAL INFRASTRUCTURE GROUP LTD
91
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'i�e I4�iunicipal i�ifnstructurc Gronp Ltd.
Date: April21, 2014
PN: 12150
To: Marilee Gadzovski, City of Pickering
CC: Tom Dole, City of Pickering
Abe Khademi, TMIG
From: Steve Hollingworth
Subject: Downtown SWM and Diversion Study
Constraints to Redevelopment at the Pickering Town Centre
j On April 1, 2Q14, TMIG met with senior staff at the City of Pickering to provide an update on the
' Downtown SWM and Diversion Study and discuss the implications of our findings and recommendations
;
on the vision for redevelopment and intensification in the,Pickering City Centre area.
� It was generally accepted by most at the meeting that the preferred solution should remain Culvert
Improvements. While the Diversion to Pine Creek alternative could potentially facilitate redevelopment at
� the south parking lot of the �Pickering Town Centre, the anticipated construction cost for the diversion
; alternafive is more than $30 Million.
�
The existing flood storage at the south
parking lot of the Pickering -Town
Centre is significant in reducing flood
levels in the downstream reaches of
Krosno Creek. The ewsting flood
storage volume should be preserved in
some form through any redevelopment
at the south parking lot of the Pickering
Town Centre. The existing flood
storage area is illustrated in Figure 1.
At the meeting, TMIG agreed to
investigate how the existing flood plain
storage could be preserved during
redevelopment of the area, and to
estimate the additional cost required to
replace the existing surface storage
within a new development.
8800 DufFerin 5trce.. Suite 2C10 i Vauohan. Oh L•=1C OCS p: 305.�35.576�� � 1.$88.�9.!€430 f: 9C�S.i38.0�55 tmig.ca
April 21, 2013
PN 12150
Page2of3
The relevant outputs from our investigations and the Krosno Creek hydrologic/hydraulic model are
summarized below.
First floor elevation at the Pickering Town Centre = 84.73 m
Overtopping elevation for Pickering Parkway / Highway 401 = 85.0 m
Storage volume at the Pickering Town Centre parking lot up to 85.0 m= 24,500 m3
100 year flood level upstream of Highway 401 = 84.66 m
100 year flood storage volume at the Pickering Town Centre = 8,800 m3
Storage volume reportedly created through mid 1980's re-design of the parking lot = 12,350 m3
Increase in downstream peak flow rates if storage is eliminated = 5% to 10%
100 year flood level upstream of Highway 401 if storage is eliminated = 85.27 m(+0.61 m)
The flood depth upstream of Highway 401 and storage volume at the south parking lot of the Pickering
Town Centre will be slightly reduced as re-development (with appropriate stormwater management
controls) proceeds in the remainder of the City Centre area.
The Stormwater Management'Report for the recent MPAC office tower (V.A. Piscione,.July 2009) was
referenced in estimating how much storage would be required for future development in the south parking
lot area of the Pickering Town Centre. Of the total 0.86 ha site, approximately 25% is the building, 55% is
surface parking, and 20% is landscaping. The quantity control target (post-to-pre, where pre is max 50%
impervious) is achieved through ponding on the building rooftop (approx. 80 m3) and surface parking area
(approx. 90 m3). The total storage volume of 170 m3 is equivalent to an average depth of 20 mm over the
0.86 ha site. The 5 mm water retention criterion is achieved through a large perforated pipe installed to
the east of the building to store and infiltrate roof runoff.
We have based our storage assessmertt on a hypothetical 1 hectare site, and have assumed that a
building will cover 50% of the site. We have also conservatively assumed that the entire site will be
raised above the existing 100 year ponding elevation of 84.66 m.
The elevation of the parking lot within the storage area identified in Figure 1 ranges from 84 m to 85 m.
We have assumed that our hypothetical site will be in one of the lower areas of the site, and have
assumed an average existing flood depth of 0.4 m over the hypothetical 1 ha site.. If the entire site is
raised above the 100 year flood level, a total of 0.4 m x 1 ha = 4,000 m3 would be lost, and should
therefore be replaced in some form as part of the redevelopment. Note that this represents almost half of
the total existing storage available at the Pickering Town Centre.
Ideally, the storage should be replaced at a similar elevation as existing (between 84 m and 85 m).. At a
minimum, the storage must be located above the invert of the Highway 401 culvert (81.5 m). It has been
assumed that the flood storage will be provided in a large underground vault, likely within the building
footprint. If the storage tank were 2 m high (82 m to 84 m}, located in the first floor below grade, it would
consume an area of approximately 2,000 m2, which is almost half of the assumed building footprint. If the
storage were provided within the building, the remainder of the first floor below ground could be used for
storage or parking.
Cost estimates for underground storage from recent flood remediation projects in the City of Toronto
range from $1,000 to $1,500 per cubic metre of storage provided. Applying this cost to the 4,000 m3
storage volume required for the hypothetical site results in a total cost of $4 Nlillion to $6 Million.
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April 21, 2013
PN 12150
Page 3 of 3
The above discussion is based on a number of conservative assumptions for a hypothetical
redevelopment on the south parking lot of the Pickering Town Centre. A comprehensive servicing and
stormwater management strategy is recommended for the entire Pickering Town Centre lands to
determine how best to implement centralized stormwater management and replacement flood storage for
all planned redevelopment. It is expected that centralized storage can be provided much more
econbmically than preserving the flood plain storage within each individual building site.