East Don Trail Environmental Assessment
APPENDIX G – Phase 3
APPENDIX G
ALTERNATIVE DESIGN CONCEPTS (PHASE 3):
EVALUATION CRITERIA, INDICATORS, AND
MEASURES FOR ASSIGNING SCORES
PHASE 3 EVALUATION CRITERIA CONSIDERED
AND REMOVED
Toronto and Region Conservation Authority
East Don Trail Environmental Assessment
APPENDIX G – Phase 3
G1. Evaluation Criteria – Trail Path Segments and
Crossing Segments
Toronto and Region Conservation Authority
East Don Trail Environmental Assessment
APPENDIX G – Phase 3
TABLE 1: TRAIL PATH ALTERNATIVE DESIGN CONCEPTS EVALUATION CRITERIA
CRITERIA
FUNCTIONAL VALUE
Consistency of trail
topography (i.e. steepness)
INDICATORS
SCORE
MEASURES FOR ASSIGNING SCORES


(+) 2
(+) 1
0
(-) 1
(-) 2
Entire trail segment maintains grade < 5%
< 10% of trail grade greater than 5%
10 - 20% of trail segment greater than 5%
> 20% of trail segment greater than 5%
Trail has segments > 10%
(+) 2
(+) 1
0
(-) 1
(-) 2
80% (+) lower score than the highest (=least impact)
60% lower score than the highest
40% lower score than the highest
20% lower score than the highest
Highest tree impact score (=most impact)
(+) 2
(+) 1
0
(-) 1
(-) 2
No impact or proximity to wetland
Trail within 30m of wetland, no impact to drainage
Trail within 15m of wetland, no impact to drainage
Trail impacts wetland drainage and/or intersects wetland boundary
Trail impacts wetland function and intersects wetland boundary
(+) 2
(+) 1
0
(-) 1
(-) 2
No steep grades or exposure to hazardous situations
No/few steep grades, no vehicle interaction, min exposure to hazardous areas
No to few steep grades, exposure to hazardous areas
Trail maintains steep grades, minimal exposure to hazardous situations
(+) 2
Least exposure to non-natural settings, closest to river
(+) 1
Second least exposure to non-natural settings, closest to river
0
Minimal exposure to non-natural settings, closest to river
(-) 1
Greatest exposure to non-natural settings, closest to river
(-) 2
Greatest exposure to non-natural settings, farthest from river
Frequency of changes in trail grades along route
The degree of change in vertical elevation (based on the distance over which
change occurs)
NATURAL AND PHYSICAL ENVIRONMENT
Potential impact to existing
 Potential number of trees to be removed
urban forest
 Individual trees preservation value as determined by tree condition, species, size
etc.
Potential impact to wetlands


Proximity of trail to wetland
The degree of potential impact on wetland drainage/function
SOCIAL AND CULTURAL ENVIRONMENT
Potential impact to trail users User exposure to hazardous situations including:
safety
 Proximity to watercourse (within 2 year floodline), rail lines, roadways (incl.
interaction with vehicular traffic)
 Sightlines
 Sharp turns
 Steep grades
Aesthetics and general user
 Variety of views/environments
experience
 Degree of exposure to natural vs. non-natural settings
 Availability of watercourse views
Potential impact to cultural
Heritage
COST
Capital Cost
Trail maintains steep grades and exposure to hazardous areas

Trail length where Stage 2 Archaeological Assessment would be required
(+) 2
(+) 1
0
(-) 1
(-) 2
0 -20 % of trail segment requires Stage 2
21 - 40% of trail segment requires Stage 2
41 - 60% of trail segment requires Stage 2
61-80% of trail segment requires Stage 2
81-100% of trail segment requires Stage 2

Relative estimated costs, based on:
 Type of surface materials used (e.g., asphalt vs. boardwalk)
 Quality of sub grade
 Thickness of base layer (high quality aggregate base course - minimum of six
inches for an asphalt trail. Thicker base courses should be used for poorer
quality sub-grade material)
 Additional materials/structures required for trial such as retaining walls and
fencing
(+) 2
(+) 1
0
(-) 1
Lowest capital costs
Within 20% of lowest capital costs
Within 40% of lowest capital costs
Within 60% of lowest costs
(-) 2
Greater than 60% of lowest capital cost
Toronto and Region Conservation Authority
East Don Trail Environmental Assessment
CRITERIA
Operational and
Maintenance Cost
APPENDIX G – Phase 3
INDICATORS
SCORE
MEASURES FOR ASSIGNING SCORES

Relative estimated cost to operate and maintain trail based on length, surface
type, susceptibility to flooding, requirement for erosion control works etc.
(+) 2
(+) 1
0
(-) 1
(-) 2
Lowest overall operating and maintenance costs
Within 20% of lowest operating and maintenance costs
Within 40% of lowest operating and maintenance costs
Within 60% of lowest operating and maintenance costs
Greater than 60% of lowest operating and maintenance costs




Approvals required
Stakeholder (e.g., local community) acceptance
Length of time to construct
Impacted services (e.g., rail line closure)
(+) 2
(+) 1
0
(-) 1
(-) 2
Strongly supported by landowners, agencies & stakeholders
Consistent with typical agency requirements, supported by stakeholders
Consistent with minimum agency requirements
May not be accepted by one landowner / agency / stakeholders
May not be accepted by two landowners / agencies / stakeholders
Flood Susceptibility

Frequency of trail flooding/susceptibility to flooding as indicated by:
 Trail length within/outside of the regulatory floodplain
 Trail length within/outside of the 5 year floodline
 Trail length within/outside of the 2 year floodline
(+) 2
(+) 1
0
(-) 1
(-) 2
Majority of trail segment outside regulatory floodplain
Majority of trail segment outside 5 year floodline
Majority of trail segment outside 2 year floodline
Entire trail inside 5 year floodline
Entire trail inside 2 year floodline
River Erosion Susceptibility

Trail susceptibility to risks of channel erosion or slope stability as indicated by the
trail length within/outside of the 100 year erosion allowance
(+) 2
(+) 1
0
(-) 1
(-) 2
Majority of trail segment is out of 100 year erosion allowance
< 10% of trail within 100 year erosion allowance
10 - 20% of trail within 100 year erosion allowance
> 20% of trail within 100 year erosion allowance
Any part within 100 year erosion allowance and bank > 2m height
TECHNICAL
Ease of Implementation
based on stakeholder/review
agency approval
*See Appendix F for the detailed description of the approach employed to assess and evaluate impact on tree
Toronto and Region Conservation Authority
East Don Trail Environmental Assessment
APPENDIX G – Phase 3
TABLE 2: TRAIL CROSSING SEGMENTS ALTERNATIVE DESIGN CONCEPTS EVALUATION CRITERIA
CRITERIA
FUNCTIONAL VALUE
Consistency of trail
topography (i.e. steepness)
INDICATORS
SCORE
MEASURES FOR ASSIGNING SCORES


(+) 2
(+) 1
0
(-) 1
(-) 2
Maintains consistent grade on both sides
Requires one transition (5-10%)
Requires transitions on both sides (5-10%)
Requires ramp / stairs on one side
Requires ramp / stairs on both sides
(+) 2
(+) 1
0
(-) 1
(-) 2
80% (+) lower score than the highest (=least impact)
60% lower score than the highest
40% lower score than the highest
20% lower score than the highest
Highest tree impact score (=most impact)
(+) 2
(+) 1
0
(-) 1
(-) 2
No potential hazards
One potential hazard
Two potential hazards
Three potential hazards
More than three potential hazards
(+) 2
(+) 1
0
(-) 1
(-) 2
Least exposure to engineered structures
Second least exposure to engineered structures
Minimal exposure to engineered structures
Second greatest exposure to engineered structures
Greatest exposure to engineered structures
Change(s) in vertical elevation of crossing structure
The degree of change in vertical elevation (based on the distance over which
change occurs)
NATURAL AND PHYSICAL ENVIRONMENT
Potential impact to existing
 Potential number of trees to be removed
urban forest
 Individual trees preservation value as determined by tree condition, species, size
etc.
SOCIAL AND CULTURAL ENVIRONMENT
Impact to User Safety
Exposure of trail users to potentially hazardous situations including:
Objectives*
 Flooding potential
 Sharp turn radius and/or potential sightline obstructions
*Railway safety assessed as
 Significant grade changes over short distances
a separate criterion (see
 Presence of existing informal paths adjacent to potentially dangerous
Technical Criteria)
infrastructure
Aesthetics and general user
 Degree of exposure to engineered structures/consistency with natural
experience
environment setting
Potential impact to cultural
heritage
COST
Capital Cost
Operational and
Maintenance Cost

Trail segment/ramp length where Stage 2 Archaeological Assessment would be
required
(+) 2
(+) 1
0
(-) 1
(-) 2
0 -20 % of trail segment requires Stage 2
21 - 40% of trail segment requires Stage 2
41 - 60% of trail segment requires Stage 2
61-80% of trail segment requires Stage 2
81-100% of trail segment requires Stage 2

Relative estimated cost to construct, based on:
 Bridges: span
 Type of rail crossing structure: grade crossing, tunnel or bridge and
associated structures (e.g., stairs and ramps), if any
(+) 2
(+) 1
0
(-) 1
(-) 2
Lowest capital costs
Within 20% of lowest capital costs
Within 40% of lowest capital costs
Within 60% of lowest costs
Greater than 60% of lowest capital cost

Relative estimated cost to operate and maintain crossing structure based on:
 Frequency of sediment removal
 Frequency of surface repair
 Bridges: abutment protection from erosion
 Bridges: replacement costs
(+) 2
(+) 1
0
(-) 1
Lowest overall operating and maintenance costs
Within 20% of lowest operating and maintenance costs
Within 40% of lowest operating and maintenance costs
Within 60% of lowest operating and maintenance costs
(-) 2
Greater than 60% of lowest operating and maintenance costs
Toronto and Region Conservation Authority
East Don Trail Environmental Assessment
APPENDIX G – Phase 3
CRITERIA
TECHNICAL
Ease of Implementation, as
indicated by
stakeholder/review agency
approval
INDICATORS
SCORE
MEASURES FOR ASSIGNING SCORES




Approvals required
Landowner/other stakeholders (e.g., local community) acceptance and support
Length of time to construct
Impacted services (e.g., potential rail line closure to construct a rail line crossing)
(+) 2
(+) 1
0
(-) 1
(-) 2
Strongly supported by landowners, agencies & stakeholders
Consistent with typical agency requirements
Consistent with minimum agency requirements
May not be accepted by one landowner / agency
May not be accepted by two landowners / agencies
Flood Susceptibility
(where applicable)

Frequency of flooding of crossing transition zone and bridge abutments, as
indicated by:
 Bridge abutments and transitions inside/outside of the regional floodplain
 Bridge abutments and transitions inside/outside of 5 year floodline
 Bridge abutments and transitions inside/outside of the 2 year floodline
(+) 2
(+) 1
0
(-) 1
(-) 2
Transitions and abutments outside of floodplain
Transitions and abutments outside of 5 year frequency
Transitions and abutments outside of 2 year frequency
Transitions and abutments inside of 5 year frequency
Transitions and abutments inside of 2 year frequency
Erosion Susceptibility
(where applicable)

Bridge crossing susceptibility to erosion (all bridges to span 25 year erosion
allowance), as indicated by bridge placement with respect to channel planform
(+) 2
(+) 1
0
(-) 1
(-) 2
Bridge perpendicular to channel, across riffle.
Bridge skewed across channel, across riffle
Bridge in transition between bend and riffle sections.
Bridge perpendicular across outside channel bend
Bridge skewed across outside channel bend
Railway safety, as preferred
by Metrolinx
(where applicable)

Potential risks associated with interaction between trail users and rail line (based
on landowner input), depending on the specific rail line crossing structure
considered ( grade crossing with controls, tunnel crossing and bridge crossing)
(+) 2
(+) 1
0
(-) 1
(-) 2
Tunnel under Metrolinx rail line. Meets minimum 3m clearance.
Tunnel under Metrolinx rail line, unable to meet 3m clearance
Bridge crossing over Metrolinx corridor, clearing >7m vertical.
Level rail crossing with safety controls.
Level rail crossing with no safety controls (i.e. existing)
*See Appendix F for the detailed description of the approach employed to assess and evaluate impact on trees
Toronto and Region Conservation Authority
East Don Trail Environmental Assessment
APPENDIX G – Phase 3
G2. Phase 3 Evaluation Criteria Considered and
Removed
TABLE 1: EAST DON TRAIL EA PHASE 3 (ALTERNATIVE DESIGN CONCEPTS) EVALUATION CRITERIA CONSIDERED AND
REMOVED
CRITERIA REMOVED
FUNCTIONAL VALUE
Multi-user Support
RATIONALE FOR REMOVAL
In Phase 3 and detailed design, all efforts will be made to meet
accessibility standards in order to provide multi-user support. All
crossings (river and rail) will be designed to comply with accessibility
standards and the trail path will be designed to be accessible where
physical constraints allow.
Pathway vertical elevation and grades affecting multi-user support are
also considered in the "Trail topography" Phase 3 evaluation criterion.
Access Requirements for
Emergency Vehicles (e.g.,
Police, EMS)
In detailed design, all efforts will be made to meet emergency vehicle
requirements. Emergency vehicles access requirements are also
considered via applying the "Maintenance vehicles requirements" guiding
principle in the Phase 3 design concept development.
Functional Value as a
Travel Route
General functional value as a travel route has been evaluated in Phase 2
of EA. In Phase 3, change in vertical elevation of trail pathway ("Trail
topography" criterion) is being used as a more specific indicator of trail
path functional value as a travel route.
NATURAL AND PHYSICAL ENVIRONMENT
Sensitive Wildlife Habitat
Three species of concern - Eastern Meadowlark (a protected species),
and Species of Concern
Wood Thrush and Milksnake (both special concern) - have the potential
to inhabit the local study area. Due to the limited amount of data available
on local distribution of these species, assessment of potential impact to
their habitat is difficult to carry out in a meaningful way. The potential
impact to these species will be addressed via mitigation/compensation
measures once the preferred design concept is selected.
For Eastern Meadowlark potential habitat will be identified based on
habitat requirements set out in these species recovery strategy and all
efforts will be made to avoid or minimize potential impacts.
For Milksnake and Wood Thrush, the focus on post-construction habitat
restoration.
Aquatic Species and
Aquatic Habitat
Aquatic habitat impacts for all design concepts were found to be very
similar - either none, minor (where a trail segment option is routed
sufficiently far away from the river’s edge so as not to cause erosion and
sediment loading) or temporary (caused by the necessary in-water work
Toronto and Region Conservation Authority
East Don Trail Environmental Assessment
CRITERIA REMOVED
APPENDIX G – Phase 3
RATIONALE FOR REMOVAL
for some river crossings).
In addition, erosion susceptibility criterion takes into account the potential
impact to aquatic habitat: a design concept/option scores lower if a trail is
routed fairly close to the river, making it more susceptible to channel
erosion impacts, thereby resulting in potential future bank protection
works and corresponding impact on aquatic habitat.
The potential impacts associated with construction are expected to be
temporary and fully mitigated via erosion and sediment control measures
as well as minimizing the removal of river bank vegetation.
Surface Drainage and
Groundwater
Potential impacts to surface drainage and groundwater were examined in
Phase 2 of EA. As the Phase 3 design concepts are very site-specific, it
is not possible to evaluate them in a meaningful way. Potential impacts
will be outlined for the design concepts selected as preferred.
East Don River Processes
The potential impacts to East Don River processes were evaluated in
Phase 2 of EA.
Physical Environment
Alteration (grading,
excavating and/or filling)
Physical environment alteration is addressed in the "Ease of
implementation" criterion: as that of a regulatory agency, it is TRCA's
preference to have none or minimal amount of grading, excavating and/or
filling in the flood plain.
TECHNICAL
Technical Feasibility
Alternatives considered not technically feasible were removed in Phase 2
of EA. Similar technical feasibility conditions are applicable to all design
concept alternatives considered in Phase 3.
Toronto and Region Conservation Authority