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GUIDING SOLUTIONS IN THE NATURAL ENVIRONMENT

MARKHAM 144 Main St. North, Suite 206 Markham, ON L3P 5T3 T)905.201.7622 F)905.201.0639

BRACEBRIDGE 126 Kimberley Avenue Bracebridge, ON P1L 1Z9 T)705.645.1050 F)705.645.6639

GUELPH 373 Woolwich Street Guelph, ON N1H 3W4 T)519.826.0419 F)519.826.9306

PETERBOROUGH 305 Reid Street Peterborough, ON K9J 3R2T) 705.243.7251

OTTAWA 470 Somerset Street West Ottawa, ON K1R 5J8 T) 613.627.2376

Geomorphic Assessment Glen Abbey Golf Club Redevelopment

Town of Oakville, Ontario

Prepared For:

Clublink Corporation ULC and ClubLink Holdings Limited

Prepared By:

Beacon Environmental Ltd.

Date: Project:

October 2016 215131.1

O c t o b e r 2 0 1 6

G l e n A b b e y G o l f C l u b R e d e v e l o p m e n t

G e o m o r p h i c A s s e s s m e n t

T a b l e o f C o n t e n t s

p a g e

1. Introduction .................................................................................................. 1

2. Policy Framework ........................................................................................ 2

2.1 Provincial Policy Statement (2014) ............................................................................... 2 2.2 Regional Municipality of Halton Official Plan (2015) ...................................................... 2

2.2.1 2015 Office Consolidation ............................................................................................ 2 2.2.1.1 Regional Natural Heritage System................................................................. 2

2.2.2 Regional Official Plan Amendment No. 38 (ROPA 38) .................................................. 3 2.3 Livable Oakville Plan (2009) ......................................................................................... 3 2.4 Conservation Authorities Act and Regulations .............................................................. 4

3. Background Review .................................................................................... 4

3.1 Climate ......................................................................................................................... 4 3.2 Watershed Conditions .................................................................................................. 4

3.2.1 Geology ....................................................................................................................... 4 3.2.2 Fluvial Geomorphology ................................................................................................ 5 3.2.3 Aquatic Habitat Community .......................................................................................... 5

3.3 Relevant Background Studies....................................................................................... 6 3.3.1 New North Oakville Transportation Corridor (Burnhamthorpe Road) – Class EA

Study – Fluvial Geomorphological Component (PARISH Geomorphic Ltd.,

2008) ........................................................................................................................... 6 3.3.2 Sixteen Mile Creek Watershed Plan (Gore & Storrie Limited and Ecoplans Ltd.

1996) ........................................................................................................................... 6 3.3.3 Town of Oakville 2010 Creek Erosion Inventory and Assessment Study

(AECOM, 2011) ........................................................................................................... 6

4. Historical Assessment ................................................................................ 7

5. Existing Conditions ..................................................................................... 8

5.1 Reach Delineation ........................................................................................................ 8 5.2 Rapid Assessments ...................................................................................................... 8

5.2.1 Methods ....................................................................................................................... 9 5.2.2 Results ........................................................................................................................ 9

5.2.2.1 Reach SMC-4 ............................................................................................... 9

6. Proposed Development Plan .................................................................... 11

7. Analysis ...................................................................................................... 11

7.1 Erosion Hazard Limit .................................................................................................. 11

8. Potential Effects and Mitigation ............................................................... 12

8.1 Erosion Hazard Limit .................................................................................................. 12

9. Policy Conformity ...................................................................................... 12

9.1 Provincial Policy Statement ........................................................................................ 12

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9.2 Regional Municipality of Halton Official Plan (2015) .................................................... 13 9.3 Livable Oakville Plan (2009) ....................................................................................... 13 9.4 Conservation Authorities Act and Regulations ............................................................ 13

10. Conclusions and Recommendations ...................................................... 13

11. References ................................................................................................. 15

F i g u r e s

Figure 1. Site Location ....................................................................................................... after page 2 Figure 2. Existing Conditions ............................................................................................. after page 8 Figure 3. Photo Location .................................................................................................. after page 10 Figure 4. Development Plan ............................................................................................ after page 12 T a b l e s

Table 1. Summary of Key Historical Observations .............................................................................. 7

Table 2. General Reach Characteristics – Sixteen Mile Creek .......................................................... 10

Table 3. Rapid Assessment Results – Sixteen Mile Creek ................................................................ 10

A p p e n d i c e s

A. Historical Aerial Imagery B. Photographic Record

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Page 1

1. Introduction

Beacon Environmental Limited (Beacon) was retained by ClubLink Corporation ULC and ClubLink Holdings Limited (ClubLink) to prepare a geomorphic assessment in support of the proposed redevelopment of the Glen Abbey Golf Club in the Town of Oakville, Regional Municipality of Halton (the “subject property”). The subject property, approximately 93 ha in area, is located in the southeast quadrant of Upper Middle Road and Dorval Drive. The northern and eastern portions of the property are occupied by a deep, well-defined valley containing the main branch of Sixteen Mile Creek (Figure 1). A small portion of the subject property drains southerly to a tributary of Glen Oak Creek.

ClubLink is proposing a redevelopment of the property to include residential and commercial development, as well as the protection of various natural features which includes the Sixteen Mile Creek valley system. The purpose of this geomorphic assessment is to identify watercourse erosion hazards and associated setbacks that pose potential constraints to the development of the subject property. This report includes a description of existing watercourse conditions, identification of features and functions, an assessment of erosion hazard considerations, identification of setbacks, and recommendation of appropriate mitigation measures to address potential impacts associated with the proposed development. Since a site-specific terms of reference process was not completed by the Town, Beacon relied upon the generic planning justification report guidelines posted on the Town’s website. Specific guidelines for the geomorphic assessment are not posted on the website. The information in this report was scoped based on our experience on numerous projects throughout Ontario, to include standard practices and protocols required to delineate erosion hazards within the subject property. Geomorphic characterization of watercourses downstream the subject property is not provided at this time. The Functional Servicing and Stormwater Management Report (FSSR; SCS 2016) provides an outline of the stormwater management criteria used to support the draft plan application. Specifically, the following tasks were undertaken in support of the study:

Background review of available materials (topographic mapping, aerial photography, watershed reports, relevant studies, site plan);

Review of environmental/hazard policies that may apply to the subject property at a provincial and municipal level;

Desktop assessment to delineate reaches based on underlying geomorphic controls;

Historical assessment on a reach basis using earliest to most recent available historic aerial photograph coverage to determine long-term trends or migration rates in channel configuration and adjustment, as well as the degree of channel or land use alteration that may have occurred within the study area;

Rapid field assessment on a reach basis to characterize existing geomorphic conditions and document evidence of active channel processes; and

Mapping analysis to delineate erosion hazards on a reach basis referencing the available historic record, existing channel planform and valley form, or using acceptable procedures and empirical models.

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2. Policy Framework

This section provides an overview of key provincial, and local environmental policies, legislation, and regulations that are directly relevant to erosion hazard lands for the subject property. This includes a review of the following legislation, policies and regulations:

Provincial Policy Statement;

Region of Halton Official Plan;

Town of Oakville Official Plan (Livable Oakville); and

Conservation Authorities Act and Ontario Regulation 162/06.

2.1 Provincial Policy Statement (2014)

The Provincial Policy Statement (MMAH 2014) issued under the Planning Act outlines areas of

provincial interest with respect to natural hazards. In support of the Policy Statement, a Technical Guide - Rivers and Streams: Erosion Hazard Limit document was prepared (MNR 2002) to outline standardized procedures for the delineation and management of riverine erosion hazards in the Province of Ontario. The guide presents erosion hazard protocols based on two generalized landform systems through which watercourses flow: confined and unconfined valley systems. Through this approach, the greater of the flooding hazard limit or meander belt width, plus an erosion access allowance, is defined to determine the erosion hazard limit of an unconfined river system. For confined valley systems, such as the section of Sixteen Mile Creek within the subject property, the erosion hazard limit is governed by geotechnical considerations, including a toe erosion setback from the watercourse, the stable slope allowance and an applicable erosion access allowance from the stable slope.

2.2 Regional Municipality of Halton Official Plan (2015)

The Halton Region Official Plan (ROP) was last consolidated in 2015. The Regional Official Plan Amendment No. 38 (ROPA 38), has been approved by the OMB. The 2015 interim office consolidation was prepared to include portions of the Plan effective September 28, 2015. 2.2.1 2015 Office Consolidation

2.2.1.1 Regional Natural Heritage System

The Sixteen Mile Creek valley which is located on the subject property is identified as part of the Regional Natural Heritage System. The valley lands are entirely within the Regional Natural Heritage System.

Per Section 114.1(4), one of the objectives of the Natural Heritage System is to direct developments to locations outside hazard lands. Hazard lands are defined as:

Uppe

r Midd

leRo

adWe

s t

Dorval Drive

Morrison Wedgewood Diversion Channel

Project 215131.1October 2016

1:15,0000 280 560140 Metres

UTM Zone 17 N, NAD 83

Site Location Figure 1Glen Abbey Golf Club Redevelopment

Geomorphic Assessment

LegendSubject Property Watercourse

G:\C

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2151

31 C

RV O

akvil

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GIS

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Glen Oak Creek Tributary

Sixteen

M il e Creek

Queen Eliz

abeth Way

Ol dAb

bey L

ane

Sources: First Base Solutions Web Mapping Service; Halton Region, 2015: Air Photo; Land Information Ontario, 2015: WatercourseBeacon Environmental, 2016: Watercourse; Fiddes Capshaw Inc., 2015: Subject Property

Glen Oak Creek

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Properties or lands that could be unsafe for development due to naturally occurring processes… Along river, stream and small inland lake systems, this means the land, including that covered by water, to the furthest landward limit of the flooding or erosion hazard limits.

2.2.2 Regional Official Plan Amendment No. 38 (ROPA 38)

A change put forward through ROPA 38 includes:

Per section 187(10) k), requires hazard land delineation including, but not limited to, floodplain delineation.

2.3 Livable Oakville Plan (2009)

As the subject property is entirely within the Town of Oakville, it is also subject to the Town’s in force Official Plan, Livable Oakville (2009). Schedule B of the Livable Oakville Plan identifies Natural Features and Hazard Lands. This schedule identifies the subject property as having Natural Features and Hazard Lands, including the floodplain and valleylands of Sixteen Mile Creek. Policies relating to Natural Areas are provided in Section 16 of Livable Oakville. Section 16.1.9 contains policies relating to valleylands. It states that development and site alteration are not permitted within valleylands or their setbacks (which for major valleys such as this is stipulated to be 15 m from the stable-top-of-bank), with the exception of recreational uses and essential public works. The limits of valleylands are defined by their long-term stable top of slope as determined through geotechnical assessments. The purpose of this designation is to ensure the long term protection of natural features and functions. Section 10.13 of the Livable Oakville document states that:

10.13.1 The delineation and regulation of hazard lands are administered by the Conservation Authorities. The general location of floodplain limits and shoreline hazard lands are conceptually shown on Schedule B. The limits of hazard lands on Schedule B may be updated without a Plan amendment.

10.13.2 No new development or site alteration is permitted within hazard lands without the approval of the Conservation Authority.

10.13.3 The Town recognizes the one zone concept for floodplain management as administered by the conservation authorities. The following uses may be permitted in the floodplain, subject to Conservation Authority approval: a) flood or erosion control structures; b) utilities and other related facilities which by their nature must be located near

water or traverse watercourses; c) passive recreational facilities; and, d) replacement of legally existing uses, buildings and structures.

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2.4 Conservation Authorities Act and Regulations

Ontario Regulation (Ont. Reg. 162/06) under the Conservation Authorities Act relates to Regulation of

Development, Interference with Wetlands and Alterations to Shoreline and Watercourses. Under this regulation, any development of site alteration within a regulated area requires a permit from Conservation Halton (CH). The Study Area includes regulated areas such as valleylands, floodplains, watercourses and wetlands within and downstream of the subject property. According to the Policy and Guidelines for the Administration of Ont. Reg. 162/06 & Land Use Planning Document (Conservation Halton 2011), development is prohibited within 15 m of the stable-top-of-bank of major valleys and 7.5 m of the stable-top-of-bank of minor valleys.

3. Background Review

3.1 Climate

Climate provides the driving energy for a fluvial system and directly influences basin hydrology and rates of channel erosion, particularly through precipitation. Precipitation records obtained from climate normals (1981-2010) recorded at the Oakville Southeast WPCP, located southeast of the subject property, averaged 61 mm per month in winter (November through February), and 77 mm in summer (July and August; Environment Canada 2015). This increase over the summer months is likely a result of convective thunderstorms. While total precipitation amounts are greater during the summer months, snowmelt and rain-on-snow events tend to produce the highest flows within a watershed.

3.2 Watershed Conditions

The subject property is situated within the lower Sixteen Mile Creek Watershed. Sixteen Mile Creek gently meanders through the subject property along the eastern property boundary. Sixteen Mile Creek drains a total area of 377 km2 into Lake Ontario and captures portions of Milton, Halton Hills, Oakville, and Mississauga (Gore and Storrie Limited & Ecoplans Ltd. 1996). The Niagara Escarpment crosses the northwest region of the watershed. A small portion of the subject property drains southerly to a tributary of Glen Oak Creek, which originates south of Dorval Drive from a concrete culvert. 3.2.1 Geology

The planimetric form of a watercourse is fundamentally a product of the channel flow regime and the availability of sediment (i.e., surficial geology) within the valley corridor. The ‘dynamic equilibrium’ of these inputs governs channel planform. These factors are influenced in smaller systems by physiography, riparian vegetation and land use.

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The watershed is underlain by Paleozoic rocks of upper Ordovician which consist of the red shale of the Queenston Formation, and the interbedded shale and limestone of the Georgian Bay Formation at the downstream end of the watershed (Gore and Storrie Limited et al. 1996). The subject property falls

within the Shale Plains physiographic region (Gore and Storrie Limited & Ecoplans Ltd. 1996; Chapman and Putnam 1984). The Queenston shale is exposed at several locations along the valley corridor within the subject property, and contributes to the sedimentological characteristics of the Sixteen Mile Creek. 3.2.2 Fluvial Geomorphology

In 2009 and again in 2011, channel morphology measurements were collected at 22 stations along Sixteen Mile Creek as part of a long term environmental monitoring program undertaken by Conservation Halton (Conservation Halton 2010). The nearest station, SXM-108, is downstream of the subject property, south of the Queen Elizabeth Way (QEW) near the railway crossing. In 2009, increased fine sediments were found at SXM-108 which was likely due to land use changes in the watershed, slower flows and large pools in summer that allowed for settling of sediments. No large-scale changes to channel morphology were noted at this site in 2011 (Conservation Halton 2013). Notable factors affecting fluvial geomorphology of Sixteen Mile Creek are diversion channels, watercourse channelization and reservoirs within the system. Two diversion channels provide flood protection for urban areas: he Morrison-Wedgewood Diversion Channel is concrete lined and diverts flows from five branches of the Morrison and Wedgewood creek systems (northeast portion of the Town of Oakville) to Sixteen Mile Creek, immediately upstream of the QEW. Throughout most of Milton, the Main branch of Sixteen Mile Creek has been channelized for flood control. In addition, tributaries in Milton, Lisgar and Town of Halton Hills are also channelized. There are three reservoirs which impact flows within the Sixteen Mile Creek watershed. They are operated for flood control, recreation and flow augmentation. All three are located upstream of Highway 25, upstream of the subject property. 3.2.3 Aquatic Habitat Community

As per the Environmental Impact Assessment (Beacon 2016), in 2011, Conservation Halton conducted fish community monitoring on Sixteen Mile Creek using Ontario Stream Assessment Protocol (OSAP) standards. A total of 1,859 fish, consisting of 30 species were captured. The fish species recorded were a mix of warmwater, coolwater and coldwater species which indicated high species and habitat diversity within the watershed. The species distribution indicated a minor shift towards more tolerant species able to endure stream instability and urban conditions (Conservation Halton 2013). The Lower Main Branch of the Creek (Sampling station SXM-108, downstream of the subject property) displayed a high diversity of fish species but a low number of total fish, indicating poor stream productivity likely due to the limited diverse habitat at the sampling stations (Conservation Halton 2013). Sixteen Mile Creek is monitored for Species at Risk (SAR) including Redside Dace (Notropis photogensis), (endangered) and Silver Shiner (Clinostomus elongatus) (threatened) (Conservation

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Halton 2013). Silver Shiner is listed as Threatened by Committee on the Status of Species at Risk in Ontario (COSSARO) and is therefore protected under the Ontario Endangered Species Act (2007).

3.3 Relevant Background Studies

3.3.1 New North Oakville Transportation Corridor (Burnhamthorpe Road) – Class EA Study – Fluvial Geomorphological Component (PARISH Geomorphic Ltd., 2008)

As part of the Class EA for the proposed extension of Burnhamthorpe Road over Sixteen Mile Creek, a geomorphic assessment and meander belt width study was completed (PARISH Geomorphic Ltd. 2008). We note that the study area for this assessment is approximately 3.3 km upstream of the subject property. Two reaches were delineated within this study area: Reach 1 extended from Dundas Street crossing to just downstream of Burnhamthorpe Road; Reach 2 extended from just south of Burnhamthorpe Road to a confluence with a tributary upstream. Within the study area, the underlying geology consisted of the red shale of the Queenston Formation, with outcrops of red shale visible on the eroded valley walls. A historical assessment was completed for the study using aerial photographs from 1954, 1978 and 1999 to assess changes in surrounding land use and channel planform. Migration rates were also measured. The meander belt widths were calculated based on the largest historical meander bend within the reach, per the Belt Width Delineation Procedures (PARISH Geomorphic Ltd. 2004). 3.3.2 Sixteen Mile Creek Watershed Plan (Gore & Storrie Limited and Ecoplans Ltd. 1996)

As part of the Halton Urban Structure Review (HUSR), the Sixteen Mile Creek Watershed Plan (Watershed Plan) was completed to inform the decision-making process for planning of urban development in Halton Region. The study delineated Sixteen Mile Creek into nine (9) subwatersheds. For each subwatershed, key resources, major land use and activities, key issues, objectives/targets, key management strategies/actions were identified. For Subwatershed 9, in which the subject property is located, the Watershed Plan identifies potential valley erosion as a key issue. 3.3.3 Town of Oakville 2010 Creek Erosion Inventory and Assessment Study (AECOM, 2011)

To inform budget forecasts, and as an update to the 2008 Erosion Assessment Study, an erosion inventory and assessment was completed for creeks within the Town of Oakville. The purpose of the study was to develop a list of priority rehabilitation areas through the documentation of existing watercourse conditions and identification of the most sensitive geomorphic areas and erosion sites with respect to risk to property and infrastructure. Sixteen Mile Creek was not included in the scope of this assessment.

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4. Historical Assessment

The following section presents an overview of historical conditions in the vicinity of the subject property with respect to land use, land cover and channel conditions. Historical analyses provide insight into the scale of natural and human-induced changes within a watershed, particularly the degree to which channel planform adjustment and land use has changed over time. In support of the historic assessment, black and white aerial photographs and digital colour imagery were analysed and compared to obtain a simple, qualitative assessment of the degree of land use and channel planform change over time (Appendix A and Table 1).

Table 1 provides a summary of specific observations regarding change in channel planform and land

use based on available historical aerial imagery.

Table 1. Summary of Key Historical Observations

Time

Period Scale, Source Observations

1965

1:20,000

Northway

Photomap/Remote Sensing

Ltd.

Surrounding lands consist of forested areas converted to

agricultural fields, with hedgerows, isolated woodlots and

naturally vegetated areas restricted to the Sixteen Mile Creek

valley system.

Sixteen Mile Creek channel has moderate sinuosity as the

planform shifts from one valley wall to the other within the

confined valley system. Dense riparian vegetation consisting of

trees along valley wall.

Valley wall contacts as the channel planform occupies the entire

valley floor.

Within the Sixteen Mile Creek valley, trees have been cleared

and grading works have commenced in preparation for the golf

course.

At the top of valley, grading works, as well as sand traps, and

greens, can be observed.

Pathways within the valley lands can be observed with 2 informal

channel crossings.

Channel works for the concrete retaining wall (near the current

middle bridge location) can be observed upstream of the

downstream informal channel crossing.

1974

1:12,000

Northway

Photomap/Remote Sensing

Ltd.

Grading works for the construction of the golf course, including

the clearing of trees within the valley lands, can be observed

within the subject property.

Bar formations can be observed along Sixteen Mile Creek

channel margins downstream of sections where the channel is in

contact with the valley wall.

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Time

Period Scale, Source Observations

2002

1:18,000

First Base Solutions

The golf course has been constructed within the subject property.

This includes 3 informal pedestrian crossing of Sixteen Mile

Creek.

An online pond has been constructed within the valley and

adjacent to the creek at the upstream end of the subject property.

A small portion of valley land along the left bank (north side of the

creek) at the downstream end of the subject property has been

converted to golf course greens. Bank protection treatment can

be observed along this bank.

Residential and commercial development has been constructed

within the surrounding previously agricultural lands. Several

major arterial roads have been constructed/realigned including

Dorval Drive to the south and the extension of Upper Middle Road

across the Sixteen Mile Creek valley at the northeast extent of

the subject property.

Grading can be observed for development adjacent to the east

end of the subject property

2012 1:18,000

First Base Solutions

Minimal changes can be observed between 2002 and 2012, with

the exception of the small residential neighbourhood that has

been constructed adjacent to the east end of the subject property.

5. Existing Conditions

5.1 Reach Delineation

To facilitate a systematic evaluation of Sixteen Mile Creek within the subject property, the watercourse was delineated into reaches (Figure 2). Reaches are homogenous sections of channel with regard to

form and function and can, therefore, be expected to behave consistently along their length to changes in hydrology and sediment inputs, as well as to other modifying factors (Montgomery and Buffington 1997; Richards et al. 1997). The portion of Sixteen Mile Creek within the subject property, was

delineated as a single reach. The determination of reach extents was based on a desktop assessment of transitions in riparian vegetation, sinuosity and degree of valley confinement, referencing available aerial imagery and topographic mapping. Verification of reach extents was undertaken in the field to confirm that mapped reach extents accurately reflect existing conditions and underlying geomorphic controls.

5.2 Rapid Assessments

In order to characterize existing geomorphic conditions along the relevant portion of Sixteen Mile Creek, rapid field assessments were conducted on September 14, 2015. The following standardized rapid visual assessment methods were applied:

SMC-4

SMC-3

1:7,5000 150 30075 Metres


Existing Conditions Figure 2

Glen Abbey Golf Club RedevelopmentGeomorphic Assessment


Sources: First Base Solutions Web Mapping Service;Halton Region, 2015: Air Photo; Land Information Ontario, 2015: Watercourse;Beacon Environmental, 2016: Watercourse, Bridge Crossing, Valley Wall Contact, Bank Protection;Fiddes Capshaw Inc., 2015: Subject Property

LegendSubject PropertyWatercourse Reach BreakBridge CrossingValley Wall Contact (Approximate)Bank Protection (Approximate)

Glen Oak Creek


Sixteen Mile Creek

Dorval Drive

Uppe

r Midd

leRo

adWe

st

North Serv

iceRoad

West

North Bridge

Middle Bridge

South Bridge

Enbridge Pipeline Structure

Pleasant View Court

RayDor Estates

Old Abbey Lane

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5.2.1 Methods

1. Rapid Geomorphic Assessment (RGA – MOE, 2003) The RGA documents observed indicators of channel instability by quantifying observations using an index that identifies channel sensitivity. Sensitivity is based on evidence of aggradation, degradation, channel widening and planimetric form adjustment. The index produces values that indicate whether the channel is stable/in regime (score <0.20), stressed/transitional (score 0.21-0.40) or in adjustment (score >0.41).

2. Rapid Stream Assessment Technique (RSAT – Galli, 1996) The RSAT uses an index to quantify overall stream health and includes the consideration of biological indicators (Galli 1996). Observations concerning channel stability, channel scouring/sediment deposition, physical in-stream habitat, water quality, and riparian habitat conditions are used to calculate a rating that indicates whether the channel is in poor (<13), fair (13-24), good (25-34), or excellent (35-42) condition.

3. Downs Classification Method (Downs 1995) The Downs (1995, outlined in Thorne et al. 1997) classification method infers present and future

potential adjustments based on physical observations, which indicate the stage of evolution, and type of adjustments that can be anticipated based on the channel evolution model. The resultant index classifies streams as stable, laterally migrating, enlarging, undercutting, aggrading, or recovering. 5.2.2 Results

Results of the rapid assessments are summarized in Table 2, Table 3 and Figure 2. A photographic record of site conditions at the time of the assessment is provided in Appendix B and Figure 3.

5.2.2.1 Reach SMC-4

Reach SMC-4 of Sixteen Mile Creek was characterized as a moderately sinuous, well-defined channel situated within a confined valley setting. Surrounding land use includes the golf course and residential development, with the upstream watershed predominantly rural/agricultural. The reach displayed a moderate gradient and low degree of entrenchment. Riparian vegetation was characterized as fragmentary, extending less than 1 channel width laterally and consisted of manicured grass within the golf course and of a mature deciduous forest along the valley wall slopes. Bankfull widths ranged from 16.9 – 33.1 m as the channel widened in the downstream direction. Bankfull depths ranged from 1.1 m in riffles to 2.5 m in pools. Bank angles ranged from 60-90 degrees with 30-60% of banks identified as exhibiting indicators of active erosion, such as scour, slumps and bank treatment failures (gabion baskets and concrete retaining walls). In the upper bank, substrate was clay and silt with the lower banks consisting of gravel and cobble comprised primarily of fragmented shale bedrock. Riffle substrate consisted of sand, gravel, and cobble and pool substrate was predominately silt and sand overlying bedrock. Overall, the sedimentological characteristics of the watercourse was comprised by weathered shale and various-sized clasts of fractured bedrock. Existing

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channel disturbances included 3 informal pedestrian crossings, the Upper Middle Road crossing spanning the width of the channel corridor, several areas of bank treatment and remnant bridge footings within the channel. Rapid assessment results indicated that Reach SMC-4 was ‘in transition’, with a score of 0.34. Widening and degradation were identified as the dominant modes of adjustment. Evidence of widening included gabion baskets outflanked, exposed tree roots, and occurrence of large organic debris. Indicators of degradation included exposed bridge footings, undermined gabion baskets, visible suspended armour layer in the bank and that the channel was worn into shale bedrock. An RSAT score of 22 indicated a ‘fair’ degree of overall ecological health, with riparian habitat conditions identified as the primary limiting factors. The Downs model reflected the RGA evaluation of this reach through a classification of e – ‘enlarging’ based on the observed initiation of continuous erosion at the channel toe (channel downcutting).

Table 2. General Reach Characteristics – Sixteen Mile Creek

Reach

Bankfull

Width

(m)

Bankfull

Depth

(m)

Riffle Substrate Riparian

Vegetation Notes

SMC-4 17-33 1.1-2.5

Gravel, cobble,

boulder, shale

bedrock

Manicured grass

(golf course),

herbaceous with

trees and shrubs

along valley wall

Valley wall contacts

Poorly formed bars

Erosion protection

Undermined gabion baskets

0.6 m undercut

Table 3. Rapid Assessment Results – Sixteen Mile Creek

Reach

Rapid Geomorphic Assessment

(RGA)

Rapid Stream Assessment

Technique (RSAT) Downs

Classification

Method Score Condition

Dominant

Modes of

Adjustment

Score Condition Limiting

Feature

SMC-4 0.34 In

transition

Widening,

degradation 22 Fair

Riparian

habitat

conditions

e – ‘enlarging’

SMC-4

SMC-3

1

2

345

67

89

10

11

12

13

14

1:7,5000 150 30075 Metres


Photo Locations Figure 3



Sources: First Base Solutions Web Mapping Service; Halton Region, 2015: Air Photo; Land Information Ontario, 2015: WatercourseBeacon Environmental, 2016: Reach Break, Watercourse, Photo Locations, Detailed Sites;Fiddes Capshaw Inc., 2015: Subject Property

LegendSubject PropertyWatercourse Reach BreakPhoto LocationToe Erosion Setback Location

1

Glen Oak Creek


Sixte en Mile Creek

Dorval Drive

Uppe

r Midd

leRo

adWe

st

North Serv

iceRoad

West

Pleasant View Court

Old Abbey Lane

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6. Proposed Development Plan

The proposed redevelopment concept is to redevelop the tableland portion of the subject lands into a mix of residential, commercial and open space uses. The residential component will consist of detached dwellings, townhouse and stacked townhouse dwellings, and apartment dwellings (extracted from the Draft Plan of Subdivision, October 2016). Office and retail commercial uses in a mixed-use format, community amenity uses, park and open space uses, natural heritage areas, buffers, and three (3) stormwater management ponds are also proposed (Figure 4).

The portion of Sixteen Mile Creek and its associated valleylands within the subject property, and will be preserved within natural heritage system blocks. The RayDor Estate, which is shown on the plan of subdivision for contextual purposes, will be retained but is not part of the application.

7. Analysis

As it relates to geomorphology, analyses were completed to address hazards associated with watercourse erosion in support of the stable-top-of-bank assessment (Golder 2016).

7.1 Erosion Hazard Limit

The erosion hazard limit associated with an unconfined watercourse/valley system considers the meander belt, which is generally defined as the lateral extent that a meandering channel has historically occupied and will likely occupy in the future. As Sixteen Mile Creek within the study area is situated within a confined valley system, the valley wall acts as a constraint to channel migration. In confined valley systems, the erosion hazard limit is determined through a geotechnical slope stability study (MNR, 2002). Technical support to geotechnical slope stability studies is typically provided from a geomorphic perspective through the recommendation of a toe erosion allowance. The toe erosion allowance can be determined through calculation of the annual recession rate (100-year migration total) of the toe of slope using reliable (historical) data records. Based on a review of the historical photographs, the watercourse appeared to be in contact with the valley wall since the earliest available period of record (Appendix A); however, due to the scale and resolution of available

historical aerial imager and degree of vegetative cover, recession rates could not be reliably determined for the relevant reaches. Alternatively, the toe erosion allowance can be determined referencing available published data and field observations regarding soil composition and watercourse conditions (MNR, 2002). Based on the findings of the field evaluation, at points of direct contact with the watercourse, the valley wall was comprised of shale bedrock throughout its height. Based on this information, and referencing Table 3 of the Technical Guide River and Stream Systems (MNR, 2002) a toe erosion allowance of 5 m is recommended in accordance with Provincial Policy (MMAH 2014). This allowance is considered

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Page 12

appropriate based on the observed shale soil structure found in this area. The 5 m toe erosion allowance setback should be applied to the watercourse bank at any location where the distance between the watercourse and the base of the valley wall is equal to or less than 15 metres (Figure 3).

8. Potential Effects and Mitigation

The following sections present the key potential negative effects of the proposed redevelopment plan as they relate to watercourse erosion, and identify mitigation opportunities and compensation measures to be utilized to minimize these potential effects.

8.1 Erosion Hazard Limit

As Sixteen Mile Creek within the study area is situated within a confined valley system, the valley wall acts as a constraint to channel migration. To address the erosion hazard limit associated with the subject property, a stable slope allowance has been determined through a geotechnical study in accordance with the PPS (Golder 2016). In order to support the stable slope allowance, a toe erosion allowance is required where the watercourse is within 15 metres of the base of the valley wall. As identified in the report by Golder (2016), a stable-top-of-bank has been delineated, with a toe erosion allowance recommendation from this report. As such, no further erosion hazard mitigation measures are required. The resultant constraint limit has been incorporated into the limit of development presented in Figure 4 of the Environmental Impact Assessment (Beacon 2016).

9. Policy Conformity

Section 2 of this report provided an overview of the erosion hazard policies and regulations of the Provincial Policy Statement, Halton Region, The Town of Oakville, and Conservation Halton. This section examines conformity with those policies and regulations.

9.1 Provincial Policy Statement

In confined valley systems, such as the section of Sixteen Mile Creek within the subject property, the erosion hazard limit is determined through a slope stability study, and where applicable, a toe erosion allowance is required to support the analysis (MNR, 2002). In accordance with the Provincial Policy Statement (MMAH 2014), a toe erosion allowance of 5 m is recommended. This allowance is considered appropriate based on the observed shale soil structure found in this area. The toe erosion allowance setback has been applied to the watercourse bank, where the watercourse is within 15 metres of the base of the valley wall.

SMC-4

SMC-3

1:7,5000 150 30075 Metres


Proposed Development Figure 4



Sources: First Base Solutions Web Mapping Service; Halton Region, 2015: Air Photo; Land Information Ontario, 2015: WatercourseBeacon Environmental, 2016: Reach Break, Watercourse, Photo Locations; Fiddes Capshaw Inc., 2015: Subject Property, Development Plan

LegendSubject PropertyWatercourse Reach BreakProposed DevelopmentStorm Water Management Pond

Glen Oak Creek


Six te en Mile Creek

Dorval Drive

Uppe

r Midd

leRo

adWe

s t

NorthServ

iceRoad

West

Pleasant View Court

RayDor Estates

Old Abbey Lane

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Page 13

9.2 Regional Municipality of Halton Official Plan (2015)

For confined systems, such as the section of Sixteen Mile Creek within the subject property, hazard land delineation, as required by the Official Plan, is to be determined through a slope stability study (see Golder 2016).

9.3 Livable Oakville Plan (2009)

Per the Livable Oakville Plan, the delineation and regulation of hazard lands are administered by the Conservation Authorities. In this case, hazard lands for the subject property are to be determined through a slope stability study (see Golder 2016 and also Section 9.4 below). Please refer to the Planning Justification Report (GSAI, 2016) for further details regarding the erosion allowance setback.

9.4 Conservation Authorities Act and Regulations

The subject property includes regulated areas such as valleylands, floodplains, watercourses and these are being retained and protected within the proposed redevelopment plan. A minimum 10 m buffer has been applied to the stable-top-of-bank of the major valley (Sixteen Mile Creek), with an additional 5 m buffer that includes trail, parkland and stormwater management features. Please refer to the Planning Justification Report (GSAI, 2016) for further details regarding the erosion allowance setback.

10. Conclusions and Recommendations

A geomorphic assessment was completed to identify watercourse erosion hazards and associated setbacks that pose potential constraints to the redevelopment of the Glen Abbey Golf Course in the Town of Oakville. The following summarizes the findings of this assessment:

A review of historical aerial photographs indicated that the Sixteen Mile Creek within the subject property consists of a well-defined channel within a deep, confined valley.

Rapid geomorphic assessments were completed for Reach SMC-4 within the subject property. Results indicated that the reach was in transition based on evidence of active channel adjustment. The RSAT assessment indicated that the reaches displayed a fair or good degree of overall health with channel stability, riparian vegetation and/or physical instream habitat identified as limiting factors.

Overall, channel morphology of the reach has been historically modified. Within the subject property, Reach SMC-4 has been altered by existing bank protection including gabion baskets, armourstone and concrete retaining walls.

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A toe erosion allowance of 5 m was recommended, where the watercourse is within 15 metres of the base of the valley wall, based on the observed shale soil structure found in this area.

A geotechnical study was completed to determine the stable slope allowance with consideration of the above, when the watercourse is within 15 metres of the base of the valley wall (Golder 2016).

Report prepared by: Beacon Environmental

Report reviewed by: Beacon Environmental

Maureen Attard, M.Sc. Geomorphic Systems Analyst

Imran Khan, M.Sc., P.Geo. Senior Geomorphologist

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11. References

AECOM. 2011. Town of Oakville 2010 Creek Erosion Inventory and Assessment Study.

Chapman and Putnam. 1984. Physiography of Southern Ontario, 3rd Edition. Ontario Geological Survey, Special Vol. 2.

Conservation Halton. 2013.

2011 Long Term Environmental Monitoring Program Grindstone Creek, Sixteen Mile Creek and Supplemental Monitoring. Conservation Halton, Burlington, ON. 176 pp.

Conservation Halton. 2010. 2009 Long Term Environmental Monitoring Program Grindstone Creek, Sixteen Mile Creek and Supplemental Monitoring. Conservation Halton, Burlington, ON. 134 pp.

Conservation Halton. 2011.

Conservation Halton (The Halton Region Conservation Authority) Policies and Guidelines for the Administration of Ontario Regulation 162/06 and Land Use Planning Policy Document April 27, 2006, Revised August 11, 2011.

Downs, P.W. 1995.

Estimating the probability of river channel adjustment. Earth Surface Processes and Landforms. 20: 687-705.

Downs, P.W. and Gregory, K.J. 2004.

River Channel Management: Towards Sustainable Catchment Hydrosystems. Oxford University Press Inc., New York, New York.

Environment Canada. 2015.

Canadian Climate Normals 1981-2010 http://climate.weatheroffice.gc.ca/climate_normals/index_e.html. Accessed June 23 2015.

Galli, J. 1996.

Rapid stream assessment technique, field methods. Metropolitan Washington Council of Governments. 36 pp.

Glen Schnarr and Associates Inc. 2016.

Planning Justification Report, Application to Amend the Official Plan of Subdivision, Town of Oakville.

Golder Associates. 2016. Geotechnical Investigation, Glen Abbey Golf Club Redevelopment, Oakville.

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Gore & Storrie Limited and Ecoplans Ltd. 1996. Sixteen Mile Creek Watershed Plan: Prepared in Support of the Halton Urban Structure Plan. Prepared for the Regional Municipality of Halton.

Halton Region Official Plan Package. 2016. 2015 Office Consolidation. Livable Oakville: Town of Oakville Official Plan. 2015 Office Consolidation Ministry of the Environment. 2003.

Stormwater Management Planning and Design Manual. Document # 4329e. Queen’s Printer for Ontario, Ontario, Canada.

Ministry of Municipal Affairs and Housing. 2014.

Provincial Policy Statement (Policy 3.1: Natural Hazards). Ministry of Natural Resources. 2002.

Technical Guide River and Stream Systems: Erosion Hazard Limit. Montgomery, D.R and J.M. Buffington. 1997.

Channel-reach morphology in mountain drainage basins. Geological Society of America Bulletin, 109 (5): 596-611.

PARISH Geomorphic Ltd. 2008. New North Oakville Transportation Corridor (Burnhamthorpe Road) – Class EA Study – Fluvial Geomorphological Component

Richards C., Haro R.J., Johnson L.B., Host G.E. 1997.

Catchment- and reach-scale properties as indicators of macroinvertebrate species traits. Freshw. Biol. 37:219–30.

SCS Consulting. 2016. Functional Servicing and Stormwater Management Report, Glen Abbey, Town of Oakville.

Appendix A

H i s t o r i c a l Ae r i a l I m a g e r y

A p p e n d i x A - H i s t o r i c A e r i a l I m a g e r y

Page A-1

Coverage: Spring 1965 Scale: 1:20,000

Image ID: 1965_A19345_58 Source: Northway Photomap/Remote Sensing Ltd.


Page A-2

Coverage: Spring 1974 Scale: 1:12,000

Image ID: C6374_14374015_L3_244 Source: Northway Photomap/Remote Sensing Ltd.


Page A-3

Coverage: 2002 Scale: 1:18,000

Image ID: N/A Source: First Base Solutions


Page A-4

Coverage: 2012 Scale: 1:18,000

Image ID: N/A Source: First Base Solutions

Appendix B

P h o t o g r a p h i c R e c o r d

A p p e n d i x B – P h o t o L o g

Page B 1

Photo 1 (Location 1).

SMC4. Looking upstream from property extent.

Note exposed shale along left bank (photo right).


SMC4. Looking downstream towards pedestrian

bridge and failing gabions along left bank (photo

right).


SMC4. Looking downstream from pedestrian

crossing towards failing gabion along left bank

and manicured riparian vegetation.


SMC4. Riffle substrate.


Page B 2


SMC4. Pedestrian path on left bank valley wall

contact.


SMC4. Looking upstream at upstream extent of

valley wall contact. Note also bank protection

along left bank.


SMC4. Looking upstream at Pedestrian bridge and

gabion baskets along left bank (photo right).


SMC4. Concrete retaining wall along right bank.


Page B 3


SMC4. Looking upstream at medial bar within the

channel. Note valley wall contact on right bank

(photo left).


SMC4. Looking downstream at valley wall contact

on right bank.


SMC4. Looking upstream towards pedestrian

bridge. Note gabion baskets along right bank

(photo left).


SMC4. Looking downstream at pedestrian

crossing and failing gabion on right bank. Note

old bridge footing within the channel under

bridge.


Page B 4


Online pond grate structure.


SMC4. Looking upstream at channel conditions.

Note valley wall contact on left bank (photo right)

and armourstone retaining wall on right bank

(photo centre).


SMC4. Looking at armourstone retaining wall on

right bank.


SMC4. Looking at upstream at valley wall contact

along left bank (photo right). Note failing storm

outfall down valley wall.


Page B 5


SMC4. Looking upstream towards Upper Middle

Road crossing.


SMC4. Looking at storm outfall on right bank.

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