HomeMy WebLinkAboutPSD-137-05
ClfJ!il]gton
REPORT
PLANNING SERVICES
Meeting:
GENERAL PURPOSE AND ADMINISTRATION COMMITTEE
Date:
Monday, November 21, 2005
Report #:
PSD-137-05
File #: PLN 17.13.6
By-law #: C PA . t( l./~ - ~ .5
Subject:
BROOKHILL NEIGHBOURHOOD SUBWATERSHED STUDY - FINAL REPORT
RECOMMENDATIONS:
It is respectfully recommended that the General Purpose and Administration Committee recommend to
Council the following:
1. THAT Report PSD-137 -05 be received;
2. THAT the Brookhill Neighbourhood Subwatershed Study - Final Report be received;
3. THAT the recommendations contained with the Brookhill Neighbourhood Subwatershed Study _
Final Report be adopted as the basis for subwatershed management within the study area;
4. THAT staff be authorized to initiate the necessary amendments to the Clarington Official Plan to
implement the recommendations of the Brookhill Neighbourhood Subwatershed Study - Final
Report; and
5. THAT all interested parties listed in this report and any delegations be advised of Council's
decision.
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Submitted by:
Reviewed by: Franklin Wu,
Chief Administrative Officer
HB/CP/DJC/df
9 November 2005
CORPORATION OF THE MUNICIPALITY OF CLARINGTON
40 TEMPERANCE STREET, BOWMANVILLE, ONTARIO L 1C 3A6 T (905)623-3379 F (905)623-0830
REPORT NO.: PSD.137.05
PAGE 2
1.0 THE STUDY FRAMEWORK AND PROCESS
1.1 Subwatershed studies assess the interactions of the natural environment with existing
and planned future land uses within a specified drainage area, using an ecosystem
approach. The Municipality of Clarington Official Plan (Section 20.2.3) requires that
subwatershed studies be conducted as a precursor to municipal consideration of future
draft plans of subdivision.
1.2 In the fall of 2002, the Municipality of Clarington hired the consulting firm of Aquafor
Beech to conduct the Brookhill Neighbourhood Subwatershed Study. The funding for
the study came from major landowners in the neighbourhood. The study area generally
includes the lands west of Bowmanville Creek to Maple Grove Road, and from Nash
Road in the north to Highway 2 to the south. The Brookhill Tributary drains approximately
333 hectares although the study area itself is almost 500 ha. The study area was
expanded to include the entire Brookhill Neighbourhood (some lands in this area drain
directly to the Bowmanville Creek and some drain to Westside Creek) and the lands
designated Future Urban Residential as identified in the Clarington Official Plan
(Attachment 1).
1.3 The purpose of this study was to investigate and inventory the natural features, identify
constraints and opportunities associated with existing/proposed land uses, and develop
a subwatershed management plan to manage the resources and provides for a
framework in which municipal planning decisions can be made. Goals of the study are to
protect groundwater resources; protect water quality; establish healthy aquatic and
terrestrial ecosystems; and minimize risks from flooding and erosion hazards.
1.4 The Brookhill Tributary consists of three smaller branches (East, Central and West)
leading to the Main Branch which converges with the Bowmanville Creek just north of the
St. Lawrence and Hudson railway bridge. The southern portion of the study area is
predominantly farmed. There are a number of rural residential properties located along
Maple Grove Road and Regional Road #57 and estate residential properties between
Regional Road #57 and the Bowmanville Creek Valley. The north portion of the study
area is largely located within the Maple Grove Provincially Significant Wetland Complex.
The East Branch drains the Maple Grove Provincially Significant Wetland and the West
and Central branches drain the rural lands west of Green Road (Attachment 2). Tile
drainage and agricultural practices within this subwatershed have had an impact
creating shallow grassed strips for overland drainage, and altering stream channels.
1.5 The study comprised 4 phases being:
1 - Establish Environmental Conditions
This included identification and evaluation of the natural features
and functions within the study area and their ecological significance;
mapping of developable lands, non-developable lands and those
lands requiring additional study.
REPORT NO.: PSD-137-05
PAGE 3
2 - Evaluate Alternative Stormwater Management Strategies
Four alternative strategies were considered:
i) use of traditional stormwater management ponds for water
quality, quantity and erosion control;
ii) use of infiltration measures for water quality control and to
control runoff volumes using centralized infiltration facilities
reducing the need for stormwater ponds. This alternative
generally requires soils with higher permeability;
iii and iv) combination of the use of infiltration measures and
stormwater management ponds to varying degrees.
Common to all strategies were recommendations for stormwater controls
supporting groundwater recharge on residential lots, the restoration of the
Brookhill Tributary, erosion control measures along the Brookhill Tributary
and Bowmanville Creek, and addressing the inadequacies of the culvert
structure at Regional Road #57.
3 - Selection of Preferred Subwatershed Plan
This phase of the study evaluated the 4 alternative strategies for
management of the stormwater within the study area. Initially, the steering
committee and landowners agreed with Option ii) to address stormwater
management. In this method, stormwater would be directed to
underground centralized infiltration structures which would distribute the
water directly into the ground, facilitating groundwater recharge.
Subsequently, the developers conducted detailed geotechnical
investigations revealing that the soils were not as consistently permeable
as originally determined. As a result, infiltration as a stormwater
management technique was not considered viable and Option i) was
adopted as the preferred strategy by the steering committee.
4 - Development of an Implementation Plan
Implementation of the preferred subwatershed plan requires the combined
efforts of landowners, developers, the Municipality and the Conservation
Authority. The study notes that prior to development, additional work may
be necessary including preliminary and detailed design of the stormwater
ponds, drainage plans, tree preservation plans and grading plans and
environmental impact studies. Details regarding Clarington's
responsibilities for implementation of this subwatershed study is provided in
Section 2 of this report.
1.6 A steering committee was established to guide the consultants in their work. The
makeup of the steering committee included the benefiting developers and their
consultants, representatives from the Ministry of Natural Resources, Region of Durham,
Central Lake Ontario Conservation Authority, municipal staff, 2 area residents and the
consulting team. There were 4 meetings of the Steering Committee.
REPORT NO.: PSD-137-05
PAGE 4
2.0 REPORT FINDINGS AND RECOMMENDATIONS
2.1 Arising from the different components of the study, came recommendations. Phase 1,
establishing environmental conditions, identified the significance of the study areas
natural features and from this, recommended which features shall be protected from
development and what measures would be necessary to ensure the ecological
significance of the area is maintained. Phase 3 identified the preferred subwatershed
plan and Phase 4 provides recommendations that would facilitate implementation of the
plan. An executive summary of the study is contained in Attachment 3 to this report.
2.2 Siqnificant Natural Features and Ecoloqical Functions
2.2.1 The study identified Class 1 natural features being the Maple Grove Provincially
Significant Wetland Complex, the East and Main Branches of the Brookhill Tributary and
the Bowmanville Creek Valley. Development within these features is prohibited. A
buffer area of 120 metres from the wetland and a buffer of 50 metres along the stream
valleys is required. An EIS shall be prepared prior to consideration of proposed
development within these buffer areas. It was also recommended that development be
prohibited within the Lake Iroquois Beach which is located in the very north portion of the
study area beyond the limits of the Bowmanville Urban Area.
2.2.2 Some Class 2 and Class 3 terrestrial resources were also identified. Development may
be permitted within these features subject to the preparation of an environmental impact
study to determine the sensitivity of the features and their functions, and the potential
impact of proposed development.
2.2.3 The study recommends the establishment of two wildlife corridors connecting the
Bowmanville Creek Valley with the Maple Grove PSW. One of these corridors is
proposed in the north portion of the study area along Nash Road and the other is
proposed in proximity to the future Longworth Road alignment (Attachment 4).
2.2.4 The study determined that the West and Central Branches of the tributary and the old
remnant channel could be abandoned as they had been severely compromised by past
agricultural activities and there was no evidence of fishery resources or aquatic habitat
within these areas.
2.3 Preferred Subwatershed Plan
2.3.1 The preferred subwatershed plan recommends the use of traditional stormwater
management ponds for water quality, quantity and erosion control. It is recommended
that there be eight (8) centralized ponds within the study area. The study identifies the
general location and size of the stormwater ponds (Attachment 4). The exact size and
location of these ponds shall be determined through stormwater management reports.
2.3.2 It is recommended that lot-level infiltration be conducted to help maintain existing
groundwater recharge rates and protect baseflow. For those lands that drain to the
Westside Creek, on-site flood control is recommended. Lands draining directly to
Bowmanville Creek do not need any flood control measures.
REPORT NO.: PSD.137.05
PAGE 5
2.4 Implementation
2.4.1 Three channels of the Brookhill Tributary are proposed to be restored. These are the
East Branch, Main Branch and West Branch Diversion Channel as they display evidence
of aquatic habitat and fishery resources. The West Branch Diversion Channel connects
the East Branch to the Main Branch, east of Green Road. Restoration will include
riparian plantings that will improve stream shading and contribute to bank stability. The
design of the stream works will be undertaken for the entire stream and the works shall
be completed prior to development.
2.4.2 Erosion control/stabilization works are required at the confluence of the Brookhill
Tributary and Bowmanville Creek and along the Bowmanville Valley in proximity to
Luverme Court. The erosion control works at the confluence of the Brookhill Tributary
and Bowmanville Creek shall be performed before upstream development is approved.
Stabilization of the erosion occurring in proximity to Luverme Court is recommended to
be undertaken before contributing upstream development (east of Bowmanville Creek) is
approved.
2.4.3 The study recommends phasing of works. For instance, as the stream rehabilitation
works and the erosion control works will determine stable slopes and floodplain limits,
the design and construction of these works are required before draft plan approval is
issued so that the upstream development limits can be finalized. Also required before
draft plan approval will be; hydraulic modelling, flood line mapping, and finalization of
development limits taking into account corridor and habitat buffers, an overall detailed
stormwater management plan, and an EIS (if needed). At the subdivision approval and
site plan approval stage, a detailed stormwater management report will be required,
design of major-minor systems and design of lot-level infiltration measures, tree
preservation plans, grading plans, and erosion and sediment control plans will also be
required.
2.4.4 Monitoring is an important component of the implementation of the subwatershed study
as it will measure the effectiveness of implementation of the recommendations of the
study and indicate whether or not changes to the subwatershed plan are needed to
ensure that the objectives are being met. It is recommended that the functioning of the
stormwater facilities be monitored, the erosion control works be monitored, and stream
restoration and fisheries be monitored. Monitoring of the stormwater facilities will be
conducted and funded by the developers. Annual monitoring reports shall be submitted
to the Municipality prior to Clarington assuming responsibility for the facility. The erosion
monitoring program will be overseen by CLOCA and Clarington and will be reviewed
every 5-10 years. Monitoring of the stream restoration and fisheries will be overseen by
CLOCA and Clarington with results being provided to DFO. Monitoring will continue for
5 years, unless otherwise determined by DFO.
2.4.5 As a result of the study recommendations, amendments to the Clarington Official Plan
are required. These amendments are predominantly mapping changes reflecting the
findings of the natural heritage inventory. Specifically, the plan needs to be revised to
reflect the Maple Grove Provincially Significant Wetland Complex, refinements to the
delineation of the Bowmanville Creek Valley and Brookhill Tributary, the identification of
REPORT NO.: PSD-137-05
PAGE 6
wildlife corridors and the removal of the stream channels west of Green Road. These
amendments will be undertaken in the context of the Brookhill Neighbourhood
Secondary Plan.
2.4.6 It is anticipated that the approximate cost of implementing the study will be 8.5 million
dollars. Funding for implementation of the subwatershed study will be covered by the
upstream developers. Some erosion control works in Bowmanville Creek Valley (in
proximity to Luverme Court) will be the responsibility of upstream developers of lands
east of Bowmanville Creek. The Municipality will be responsible for managing the cost
sharing agreement for the stream rehabilitation works and erosion control works.
3.0 PUBLIC INPUT
3.1 Two Public Information Centres were held. The first P.I.C. was held in November 2003
to present the findings of Phase 1 - Existing Conditions. A second P.I.C. was held to
present the draft final Subwatershed Report in September 2005. At each P.I.C., the
consultant presented the findings to date followed by questions from the public. There
were between 30-40 people at both P.I.C.s.
3.2 Many of the public expressed similar comments and questions including: when will
development occur; what type of development can be expected; and what happens if my
well water is impacted? Questions were also raised regarding potential of development
within the setback areas and what the environmental impact study process entails. One
resident felt that the tributary was not worthy of protection and that it should be piped.
Residents were told that the Official Plan designates the lands as urban residential and
that applications for residential plans of subdivision have been submitted on some of the
land within the study area. Residents were advised that the Region has a well
interference policy whereby potable water will be restored to a home owner if it can be
shown that development has directly impacted the quality/quantity of their well. The
environmental impact study process was explained and residents were advised that an
EIS will determine if development may occur within a setback area, what type of
development would be appropriate and whether any mitigation would be needed.
3.3 Comments on the draft final Subwatershed Study were received from the developer's
consultants. It was felt that the requirement for erosion/stabilization works and stream
rehabilitation works should not be funded by the benefiting developers and should not be
a requirement prior to subdivision approval. The East Branch, Main Branch and West
Branch Diversion Channel have been identified as possessing aquatic habitat and
fishery resources. Restoration and rehabilitation of these branches will improve aquatic,
fishery and terrestrial resources, provide corridor linkages, improve temperature and
morphologic characteristics and create a stable channel form. The improvements to the
channels will also provide an opportunity to refine the floodplain limits and address grade
modifications that may improve serviceability of the lands, directly benefiting the
landowners. It is recommended that the restoration of the stream be planned, designed
and completed prior to or in conjunction with any upstream urban development. It is
important that this work be completed in it's entirety prior to future urban development as
REPORT NO.: PSD.137.05
PAGE 7
it will establish many standards for future development including flood lines and setbacks.
Funding for the rehabilitation of the channels shall be paid 100% by the developers.
It was also questioned why restore the West Branch Diversion Channel just east of
Green Road. This channel exhibits aquatic habitat and fishery resources, drains
approximately 100 hectares, and will enhance the open space network. As such, it is
recommended that this portion of the channel be restored.
3.4 The Region of Durham Works Department commented on the draft final Subwatershed
Study expressing concern with the potential increase in Regional Storm water levels at
Regional Road 57. It was clarified with the Region that the frequency of flooding at
Regional Road 57 will not increase for the more frequent storm events as upstream
development will provide stormwater management facilities to control flows to pre-
development rates up to and including the 100 year storm event. With the future
construction of a new collector road (extension of Stevens Road) at Regional Road 57
just north of the Regional Police Station, the opportunity exists to review the
feasibility/necessity of increasing the capacity of the culvert structure at that time. Until
then, it is recommended that prior to upstream development, the capacity of the culvert
be increased and the funding for this improvement would be shared by upstream
developers.
4.0 CONCLUSIONS
4.1 The completion of the subwatershed study provides the foundation and framework for
undertaking the Secondary Plan. This study has identified those lands that shall be
protected, sets out where additional studies may be needed, established the need and
general location for wildlife corridors that will connect the Bowmanville Creek Valley with
the Maple Grove Wetland Complex, and lastly provides a management plan for
stormwater.
4.2 This subwatershed study has been received by the Public and is supported by the
steering committee. All comments made on the draft final report have been addressed
by the consultant. Municipality Staff support the findings and 'recommendations of the
study. It is recommended that the Final Brookhill Subwatershed Study be adopted as the
basis for subwatershed management and development within the study area.
Attachments:
Attachment 1 - Brookhill Neighbourhood Subwatershed Study Area
Attachment 2 - Brookhill Tributary
Attachment 3 - Executive Summary of the Brookhill Neighbourhood Subwatershed Study
Attachment 4 - Recommended Subwatershed Management Plan
REPORT NO.: PSD-137-05
PAGE 8
Interested parties to be notified of Council and Committee's decision:
Tom Veljanovski
Peter Feddema
Mr. & Mrs. Lazotasevski
Mr. Jose Neto
Ted Watson
Matt Barrese
Louis Balogh
George Milosh
Stefan Neshevich
Charlie Mason
Peter Stoddart
Brian Catherwood
Mike Mayko
Gary & Joanna English
Jim Geddes
Joe Vanderheyden
Don Sudsbury Sr.
Don Sudsbury Jr.
Robert Stevens
Derek Baird
Mark Koenig
Ms. Roslyn Houser
Mr. Robert Howe
Vanstone Mill Inc.
Mike Linden
Ken Peters
Irwin Hamilton
Jim Mercer
Bruce Fischer
Peter Smith
Cora Tonno
Thorsten Koseck
Rick Tranquatta
Phil Lack
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Attachment #3
To Report PSD-137-05
EXECUTIVE SUMMARY
The Municipality of CIa ring ton, together with the Central Lake Ontario Conservation Authority
(CLOCA) have undertaken a Subwatershed Planning Study for the "Brookhill Neighbourhood".
The study goal was defmed as: "development of a management plan which is designed to allow
environmentally responsible resource management and municipal planning decisions to be made
as land use changes occur within the subwatershed." The study included four general phases:
Establish existing environmental conditions;
Evaluate alternative subwatershed management strategies;
Select a recommended Subwatershed Plan; and
· Develop an implementation plan.
Phase 1 - Establish Existing Environmental Conditions
The existing environmental resources within the study area were defined in order to identifY key
features and functions, to establish baseline conditions for the assessment of potential impacts from
future urban development, and to identifY development constraints and potential future
opportunities. A summary of the key environmental features and functions to be considered is
provided below:
The geology ofthe study area is highly variable, with areas ofthick sand and gravel at the
northern limits, to areas of clay and till in the central and southern portions of the study
area. Given its function as both a drinking water aquifer, and contributor of base flow to
regional coldwater streams such as Bowmanville Creek, the recharge potential ofthe sand
and gravel ofthe Iroquois Beach feature in the northwest portion of the study area should
be protected from future urban development. The sand plains within the central portion
of the study area also act as a drinking water aquifer. It is therefore recommended that
stormwater management planning for future development incorporate infiltration measures
to maintain the existing, moderate rates of groundwater recharge, and the existing
groundwater quality.
S.l
The hydrologic response ofthe Brookhill Tributary was assessed for existing and ultimate
landuse scenarios. Future flood controls are necessary to prevent significant increases in
peak flow rates within the watercourse. Flood controls are not required for lands draining
directly to Bowmanville Creek, however. For lands along Highway No.2 draining to
West Side Creek, flood control is provided within downstream stormwater ponds,
however, future commercial developments will require on-site flood controls to meet
existing storm sewer capacities.
· The Regulatory floodplain limits of the Brookhill Tributary and of Bowmanville Creek
were identified as constraints to future development. It is noted that recent grading works
near the diversion channel and remnant channel may have remove the remnant channel
from the Regulatory storm floodplain in this area.
Given the existing fish communities of the Brookhill Tributary (warmwater) and of
Bowmanville Creek (coldwater), future urban development within the study area should
incorporate "Levell" or "enhanced" water quality controls, including measures to control
runoff temperature. Lower suspended solids loadings would also be expected with erosion
control/stabilization works on Bowmanville Creek and the Brookhill Tributary.
· The existing stream morphology ofthe watercourses were characterized. The Brookhill
Tributary is relatively stable within its upstream reaches, with erosion and instability
increasing in the downstream reaches towards the confluence with Bowmanville Creek.
Due to the failure of Vanstone Dam, vanous adjustments, particularly
downcutting/incision, have been occurring at the confluence. As such, future urban
development should include erosion controls so that natural rates of erosion are not
exacerbated. Further rehabilitation/stabilization opportunities were also identified.
· The existing fish communities ofthe study area include a warmwater community within
the Main Branch ofthe Brookhill Tributary and a coldwater community in Bowmanville
Creek. Stream reaches of the Brookhill Tributary to the east of Green Road were
identified for protection as they either contribute to, or provide downstream fish habitat.
S.2
Aquatic habitat buffers/setbacks for Bowmanville Creek and the Brookhill Tributary were
established as 30 metres, and 15 metres (both sides), respectively. Stormwater
management requirements, in terms of water quality controls and erosion controls were
also identified for future urban development. Other potential opportunities to improve fish
habitat were also identified, including stream rehabilitation/stabilization works, baseflow
enhancement, and improved riparian cover,
The existing terrestrial features within the study area were inventoried and classified. Class
1 features, including the Maple Grove wetland, the headwater communities of the
Brookhill Tributary and the Bowmanville Creek valley communities, were identified for
protection. These forests are among the highest quality in the study area, covering an
extensive area, and represent potentially significant habitat for breeding birds. Other
features, including a thicket swamp, plantations, and features within the Brookhill
Tributary were defmed as Class 2 features. Some level of development may be permitted
to alter the size and physical form ofa Class 2 area, provided that ecological functions are
protected and maintained. An environmental impact study (EIS) is recommended for
alterations to these features and for lands within 50 metres of Class 1 features, and within
120 metres of the Maple Grove PSW. Class 3 features represent preservation
opportunities.
The environmental corridors of the Brookhill Tributary and Bowmanville Creek were
identified as constraints to future development. These lands encompass erosion hazard
lands (Le. meander belts, erosion and slope stability allowances), aquatic buffers/setbacks,
valley features, and an additional 5 metre setback for valley access.
Phase 2 - Evaluate Alternative Subwatershed Management Strategies
Subwatershed goals and objectives were defmed for the various environmental resources within
the study area and alternative best management practices (BMP's) to meet these objectives were
reviewed. Based on the potential BMP's, a set of four alternative management strategies were
formulated for evaluation and discussion. Several measures which are common within all four
strategies including:
S.3
no development within the Lake Iroquois Beach;
no development within the floodplain or stream/environmental corridors as defmed by:
erosion/slope stability hazards (confmed reaches);
meander belt width (unconfmed reaches);
aquatic habitat buffers/setbacks;
· top-of bank;
municipal environmentaVaccess setback.
on-site flood controls for developments draining to West Side Creek;
Levell water quality control, including temperature controls;
· preservation of existing groundwater recharge rates;
erosion/stabilization works to mitigate on-going erosion at identified sites, improve bank
stability, and remove a barrier to fish migration at the mouth ofthe Brookhill Tributary;
stream rehabilitation to create more stable instream habitat conditions within the Brookhill
Tributary, including the removal of existing pipe/tile drainage to restore a riffle-pool
morphology, and riparian planting to improve stream shading and contribute to bank
stability;
protection of Class 1 terrestrial features including the Maple Grove provincially significant
wetland (PSW), and woodlots within the Bowmanville Creek valley and Brookbill
Tributary corridor;
· assessment of Class 2 areas with future Environmental Impact Studies (ElS's);
establishing wildlife corridor linkages between the Maple Grove wetland complex and the
Bowmanville Creek valley at the following locations:
the future Longworth Avenue extension (min. width 60 to 100m);
the south side of Nash Road (min.. width 100m); and
along the Brookbill Creek stream/environmental corridor.
Alternative Strategy No.1
In general, this strategy is characterized by traditional stormwater management practices. In
addition to the measures listed above which are common to all of the alternative strategies, the
components of this strategy include the following:
SA
.
basic lot-level source controls to maintain groundwater recharge;
stormwater management ponds for water quality control;
stormwater management ponds for erosion control;
stormwater management ponds for flood (quantity) control (Brookhill Tributary only).
.
Alternative Strategy No.2
This strategy is very similar to Strategy No.1 in that stormwater management ponds would be used
to provide erosion control and flood (quantity) controls. However, this strategy would employ
centralized infiltration facilities such as exfiltration systems and/or infiltration basins to provide
both groundwater recharge and water quality control. The use of such infiltration measures
would result in moderately smaller stormwater ponds due to the reduced volume requirements.
Alternative Strategy No.3
This strategy is similar to Strategy No.2 in that centralized infiltration facilities such as exfiltration
systems and/or infiltration basins would be used to provide both groundwater recharge and water
quality control. However, this strategy is intended to significantly reduce the storage requirements
for future stormwater management ponds. To do so, the goals of groundwater recharge
protection, surface water quality protection, and erosion control would be integrated using
enhanced infiltration targets for the centralized infiltration facilities. This would significantly
reduce the erosion control storage requirements within future stormwater management ponds.
Further, the Regional Road 57 culvert structure would be replaced in order to forego flood
(quantity) control requirements within the Brookhill Tributary.
Alternative Strategy No.4
The intent of this strategy would be to enhance the existing aquatic habitat conditions and
eliminate the need for stormwater ponds. This strategy consists of the following measures:
· provIsIon of enhanced infiltration measures for water quality control, groundwater
recharge and base flow enhancement, and to reduce future runoff volumes and erosion
stresses;
stream restoration within the Brookhill Tributary to create a riffle-pool stream morphology
S.5
.
capable of conveying the flow regime associated with the future urban setting and provides
aquatic habitat enhancement features; and
replacement ofthe Regional Road 57 culvert structure in order to forego flood (quantity)
control requirements within the Brookhill Tributary and to remove a barrier to fish
migration.
Provided that construction of these measures would result in a stream corridor with sufficient
capacity to accommodate the future flow regime, stormwater management ponds (i.e. for erosion
and flood control) would not be required with Strategy No.4.
Phase 3 - Select A Recommended Subwatershed Plan
Following a Public Information Centre and a series of meetings between Municipal staff, CLOCA
staff, local residents, and representatives ofthe development community, alternative Strategy No.
4 was initially selected to form the proposed Subwatershed Management Plan.
However, subsequent geotechnical investigations on behalf of the landowners groups
recommended that centralized infiltration facilities not be used for stormwater management. This
recommendation was due in part to low permeability and percolation rates in some parts of the
study area, and also due to the fact that sandy soils which were suitable for infiltration were found
to be localized in nature and sometimes underlain with less permeable soils.
Therefore, Alternative Strategy No. I, which does not include the use of centralized infiltration
facilities, was selected to form the Recommended Subwatershed Plan.
Phase 4 - Develop an Implementation Plan
Implementation of the Recommended Subwatershed Plan will require the combined efforts of
landowners, developers, the Municipality, the Conservation Authority, and public/special interest
groups. Implementation considerations for the Subwatershed Management Plan were reviewed
with respect to the following:
S.6
· future study requirements, including stormwater management plans, environmental impact
studies, environmental assessments, hydraulics and floodplain mapping, and tree
preservation plans;
prioritization/phasing considerations, including inter-dependancies ofseveral components
ofthe Subwatershed Plan, and the necessary works to be completed:
first, at a broad draft plan level; and
· subsequently, at the more detailed subdivision/site plan level.
· costs estimates for various components of the Subwatershed Plan, and funding
responsibilities between the Municipality and development community, including those
which may require cost-sharing agreements;
· approval requirements for the various studies and works recommended In the
Subwatershed Plan; and
· recommendations with respect to future monitoring requirements, including:
stormwater facility monitoring;
erosion monitoring; and
· stream restoration and fisheries monitoring.
S.7
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